treewide: refresh kmalloc_obj() conversionsgrafted

This is another run of the Coccinelle script for converting kmalloc()
family of allocations to kmalloc_obj() via the existing rules in
scripts/coccinelle/api/kmalloc_objs.cocci

This catches both the set of kmalloc() uses added since the first
kmalloc_obj() conversions in v7.0 and adds a large group missed in the
first pass due to Coccinelle not interacting well with the cleanup.h
scoped_...() family of macros[1]. I worked around this with spatch's
"--macro-file" argument to a file with all the scoped_...() macros mapped
to Coccinelle's YACFE_ITERATOR[2] as that was the closest viable control
flow indicator I could find.

Build tested allmodconfig on x86, arm64, arm, loongarch, mips, powerpc,
riscv, and s390 with no new warnings.

Link: https://lore.kernel.org/lkml/202609021314.8A9C0B8@keescook/ [1]
Link: https://github.com/coccinelle/coccinelle/blob/master/standard.h [2]
Signed-off-by: Kees Cook <kees+treewide@kernel.org>

1 files changed, 11121 insertions, 0 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
new file mode 100644
index 000000000..680b34a63
--- /dev/null
+++ b/drivers/md/md.c
@@ -0,0 +1,11121 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+   md.c : Multiple Devices driver for Linux
+     Copyright (C) 1998, 1999, 2000 Ingo Molnar
+
+     completely rewritten, based on the MD driver code from Marc Zyngier
+
+   Changes:
+
+   - RAID-1/RAID-5 extensions by Miguel de Icaza, Gadi Oxman, Ingo Molnar
+   - RAID-6 extensions by H. Peter Anvin <hpa@zytor.com>
+   - boot support for linear and striped mode by Harald Hoyer <HarryH@Royal.Net>
+   - kerneld support by Boris Tobotras <boris@xtalk.msk.su>
+   - kmod support by: Cyrus Durgin
+   - RAID0 bugfixes: Mark Anthony Lisher <markal@iname.com>
+   - Devfs support by Richard Gooch <rgooch@atnf.csiro.au>
+
+   - lots of fixes and improvements to the RAID1/RAID5 and generic
+     RAID code (such as request based resynchronization):
+
+     Neil Brown <neilb@cse.unsw.edu.au>.
+
+   - persistent bitmap code
+     Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc.
+
+
+   Errors, Warnings, etc.
+   Please use:
+     pr_crit() for error conditions that risk data loss
+     pr_err() for error conditions that are unexpected, like an IO error
+         or internal inconsistency
+     pr_warn() for error conditions that could have been predicated, like
+         adding a device to an array when it has incompatible metadata
+     pr_info() for every interesting, very rare events, like an array starting
+         or stopping, or resync starting or stopping
+     pr_debug() for everything else.
+
+*/
+
+#include <linux/sched/mm.h>
+#include <linux/sched/signal.h>
+#include <linux/kthread.h>
+#include <linux/blkdev.h>
+#include <linux/blk-integrity.h>
+#include <linux/badblocks.h>
+#include <linux/sysctl.h>
+#include <linux/seq_file.h>
+#include <linux/fs.h>
+#include <linux/poll.h>
+#include <linux/ctype.h>
+#include <linux/string.h>
+#include <linux/hdreg.h>
+#include <linux/proc_fs.h>
+#include <linux/random.h>
+#include <linux/major.h>
+#include <linux/module.h>
+#include <linux/reboot.h>
+#include <linux/file.h>
+#include <linux/compat.h>
+#include <linux/delay.h>
+#include <linux/raid/md_p.h>
+#include <linux/raid/md_u.h>
+#include <linux/raid/detect.h>
+#include <linux/slab.h>
+#include <linux/percpu-refcount.h>
+#include <linux/part_stat.h>
+
+#include "md.h"
+#include "md-bitmap.h"
+#include "md-cluster.h"
+
+static const char *action_name[NR_SYNC_ACTIONS] = {
+	[ACTION_RESYNC]		= "resync",
+	[ACTION_RECOVER]	= "recover",
+	[ACTION_CHECK]		= "check",
+	[ACTION_REPAIR]		= "repair",
+	[ACTION_RESHAPE]	= "reshape",
+	[ACTION_FROZEN]		= "frozen",
+	[ACTION_IDLE]		= "idle",
+};
+
+static DEFINE_XARRAY(md_submodule);
+
+static const struct kobj_type md_ktype;
+
+static DECLARE_WAIT_QUEUE_HEAD(resync_wait);
+
+/*
+ * This workqueue is used for sync_work to register new sync_thread, and for
+ * del_work to remove rdev, and for event_work that is only set by dm-raid.
+ *
+ * Noted that sync_work will grab reconfig_mutex, hence never flush this
+ * workqueue whith reconfig_mutex grabbed.
+ */
+static struct workqueue_struct *md_misc_wq;
+
+static int remove_and_add_spares(struct mddev *mddev,
+				 struct md_rdev *this);
+static void mddev_detach(struct mddev *mddev);
+static void export_rdev(struct md_rdev *rdev);
+static void md_wakeup_thread_directly(struct md_thread __rcu **thread);
+
+/*
+ * Default number of read corrections we'll attempt on an rdev
+ * before ejecting it from the array. We divide the read error
+ * count by 2 for every hour elapsed between read errors.
+ */
+#define MD_DEFAULT_MAX_CORRECTED_READ_ERRORS 20
+/* Default safemode delay: 200 msec */
+#define DEFAULT_SAFEMODE_DELAY ((200 * HZ)/1000 +1)
+/*
+ * Current RAID-1,4,5,6,10 parallel reconstruction 'guaranteed speed limit'
+ * is sysctl_speed_limit_min, 1000 KB/sec by default, so the extra system load
+ * does not show up that much. Increase it if you want to have more guaranteed
+ * speed. Note that the RAID driver will use the maximum bandwidth
+ * sysctl_speed_limit_max, 200 MB/sec by default, if the IO subsystem is idle.
+ *
+ * Background sync IO speed control:
+ *
+ * - below speed min:
+ *   no limit;
+ * - above speed min and below speed max:
+ *   a) if mddev is idle, then no limit;
+ *   b) if mddev is busy handling normal IO, then limit inflight sync IO
+ *   to sync_io_depth;
+ * - above speed max:
+ *   sync IO can't be issued;
+ *
+ * Following configurations can be changed via /proc/sys/dev/raid/ for system
+ * or /sys/block/mdX/md/ for one array.
+ */
+static int sysctl_speed_limit_min = 1000;
+static int sysctl_speed_limit_max = 200000;
+static int sysctl_sync_io_depth = 32;
+
+static int speed_min(struct mddev *mddev)
+{
+	return mddev->sync_speed_min ?
+		mddev->sync_speed_min : sysctl_speed_limit_min;
+}
+
+static int speed_max(struct mddev *mddev)
+{
+	return mddev->sync_speed_max ?
+		mddev->sync_speed_max : sysctl_speed_limit_max;
+}
+
+static int sync_io_depth(struct mddev *mddev)
+{
+	return mddev->sync_io_depth ?
+		mddev->sync_io_depth : sysctl_sync_io_depth;
+}
+
+static void rdev_uninit_serial(struct md_rdev *rdev)
+{
+	if (!test_and_clear_bit(CollisionCheck, &rdev->flags))
+		return;
+
+	kvfree(rdev->serial);
+	rdev->serial = NULL;
+}
+
+static void rdevs_uninit_serial(struct mddev *mddev)
+{
+	struct md_rdev *rdev;
+
+	rdev_for_each(rdev, mddev)
+		rdev_uninit_serial(rdev);
+}
+
+static int rdev_init_serial(struct md_rdev *rdev)
+{
+	/* serial_nums equals with BARRIER_BUCKETS_NR */
+	int i, serial_nums = 1 << ((PAGE_SHIFT - ilog2(sizeof(atomic_t))));
+	struct serial_in_rdev *serial = NULL;
+
+	if (test_bit(CollisionCheck, &rdev->flags))
+		return 0;
+
+	serial = kvmalloc(sizeof(struct serial_in_rdev) * serial_nums,
+			  GFP_KERNEL);
+	if (!serial)
+		return -ENOMEM;
+
+	for (i = 0; i < serial_nums; i++) {
+		struct serial_in_rdev *serial_tmp = &serial[i];
+
+		spin_lock_init(&serial_tmp->serial_lock);
+		serial_tmp->serial_rb = RB_ROOT_CACHED;
+	}
+
+	rdev->serial = serial;
+	set_bit(CollisionCheck, &rdev->flags);
+
+	return 0;
+}
+
+static int rdevs_init_serial(struct mddev *mddev)
+{
+	struct md_rdev *rdev;
+	int ret = 0;
+
+	rdev_for_each(rdev, mddev) {
+		ret = rdev_init_serial(rdev);
+		if (ret)
+			break;
+	}
+
+	/* Free all resources if pool is not existed */
+	if (ret && !mddev->serial_info_pool)
+		rdevs_uninit_serial(mddev);
+
+	return ret;
+}
+
+/*
+ * rdev needs to enable serial stuffs if it meets the conditions:
+ * 1. it is multi-queue device flaged with writemostly.
+ * 2. the write-behind mode is enabled.
+ */
+static int rdev_need_serial(struct md_rdev *rdev)
+{
+	return (rdev && rdev->mddev->bitmap_info.max_write_behind > 0 &&
+		rdev->bdev->bd_disk->queue->nr_hw_queues != 1 &&
+		test_bit(WriteMostly, &rdev->flags));
+}
+
+/*
+ * Init resource for rdev(s), then create serial_info_pool if:
+ * 1. rdev is the first device which return true from rdev_enable_serial.
+ * 2. rdev is NULL, means we want to enable serialization for all rdevs.
+ */
+void mddev_create_serial_pool(struct mddev *mddev, struct md_rdev *rdev)
+{
+	int ret = 0;
+	unsigned int noio_flags;
+
+	if (!test_bit(MD_SERIALIZE_POLICY, &mddev->flags) &&
+	    rdev && !rdev_need_serial(rdev) &&
+	    !test_bit(CollisionCheck, &rdev->flags))
+		return;
+
+	noio_flags = memalloc_noio_save();
+	if (!rdev)
+		ret = rdevs_init_serial(mddev);
+	else
+		ret = rdev_init_serial(rdev);
+	if (ret)
+		goto out;
+
+	if (mddev->serial_info_pool == NULL) {
+		mddev->serial_info_pool =
+			mempool_create_kmalloc_pool(NR_SERIAL_INFOS,
+						sizeof(struct serial_info));
+		if (!mddev->serial_info_pool) {
+			rdevs_uninit_serial(mddev);
+			pr_err("can't alloc memory pool for serialization\n");
+		}
+	}
+out:
+	memalloc_noio_restore(noio_flags);
+}
+
+/*
+ * Free resource from rdev(s), and destroy serial_info_pool under conditions:
+ * 1. rdev is the last device flaged with CollisionCheck.
+ * 2. when bitmap is destroyed while policy is not enabled.
+ * 3. for disable policy, the pool is destroyed only when no rdev needs it.
+ */
+void mddev_destroy_serial_pool(struct mddev *mddev, struct md_rdev *rdev)
+{
+	if (rdev && !test_bit(CollisionCheck, &rdev->flags))
+		return;
+
+	if (mddev->serial_info_pool) {
+		struct md_rdev *temp;
+		int num = 0; /* used to track if other rdevs need the pool */
+
+		rdev_for_each(temp, mddev) {
+			if (!rdev) {
+				if (!test_bit(MD_SERIALIZE_POLICY,
+					      &mddev->flags) ||
+				    !rdev_need_serial(temp))
+					rdev_uninit_serial(temp);
+				else
+					num++;
+			} else if (temp != rdev &&
+				   test_bit(CollisionCheck, &temp->flags))
+				num++;
+		}
+
+		if (rdev)
+			rdev_uninit_serial(rdev);
+
+		if (num)
+			pr_info("The mempool could be used by other devices\n");
+		else {
+			mempool_destroy(mddev->serial_info_pool);
+			mddev->serial_info_pool = NULL;
+		}
+	}
+}
+
+static struct ctl_table_header *raid_table_header;
+
+static const struct ctl_table raid_table[] = {
+	{
+		.procname	= "speed_limit_min",
+		.data		= &sysctl_speed_limit_min,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "speed_limit_max",
+		.data		= &sysctl_speed_limit_max,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{
+		.procname	= "sync_io_depth",
+		.data		= &sysctl_sync_io_depth,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+};
+
+static int start_readonly;
+
+/*
+ * The original mechanism for creating an md device is to create
+ * a device node in /dev and to open it.  This causes races with device-close.
+ * The preferred method is to write to the "new_array" module parameter.
+ * This can avoid races.
+ * Setting create_on_open to false disables the original mechanism
+ * so all the races disappear.
+ */
+static bool create_on_open = true;
+static bool legacy_async_del_gendisk = true;
+static bool check_new_feature = true;
+
+/*
+ * We have a system wide 'event count' that is incremented
+ * on any 'interesting' event, and readers of /proc/mdstat
+ * can use 'poll' or 'select' to find out when the event
+ * count increases.
+ *
+ * Events are:
+ *  start array, stop array, error, add device, remove device,
+ *  start build, activate spare
+ */
+static DECLARE_WAIT_QUEUE_HEAD(md_event_waiters);
+static atomic_t md_event_count;
+void md_new_event(void)
+{
+	atomic_inc(&md_event_count);
+	wake_up(&md_event_waiters);
+}
+EXPORT_SYMBOL_GPL(md_new_event);
+
+/*
+ * Enables to iterate over all existing md arrays
+ * all_mddevs_lock protects this list.
+ */
+static LIST_HEAD(all_mddevs);
+static DEFINE_SPINLOCK(all_mddevs_lock);
+
+static bool is_md_suspended(struct mddev *mddev)
+{
+	return percpu_ref_is_dying(&mddev->active_io);
+}
+/* Rather than calling directly into the personality make_request function,
+ * IO requests come here first so that we can check if the device is
+ * being suspended pending a reconfiguration.
+ * We hold a refcount over the call to ->make_request.  By the time that
+ * call has finished, the bio has been linked into some internal structure
+ * and so is visible to ->quiesce(), so we don't need the refcount any more.
+ */
+static bool is_suspended(struct mddev *mddev, struct bio *bio)
+{
+	if (is_md_suspended(mddev))
+		return true;
+	if (bio_data_dir(bio) != WRITE)
+		return false;
+	if (READ_ONCE(mddev->suspend_lo) >= READ_ONCE(mddev->suspend_hi))
+		return false;
+	if (bio->bi_iter.bi_sector >= READ_ONCE(mddev->suspend_hi))
+		return false;
+	if (bio_end_sector(bio) < READ_ONCE(mddev->suspend_lo))
+		return false;
+	return true;
+}
+
+bool md_handle_request(struct mddev *mddev, struct bio *bio)
+{
+check_suspended:
+	if (unlikely(md_cloned_bio(mddev, bio))) {
+		/*
+		 * This bio is an MD cloned bio and already holds an
+		 * active_io reference, so percpu_ref_get() is safe here.
+		 */
+		percpu_ref_get(&mddev->active_io);
+	} else {
+		if (is_suspended(mddev, bio)) {
+			/* Bail out if REQ_NOWAIT is set for the bio */
+			if (bio->bi_opf & REQ_NOWAIT) {
+				bio_wouldblock_error(bio);
+				return true;
+			}
+			wait_event(mddev->sb_wait, !is_suspended(mddev, bio));
+		}
+		if (!percpu_ref_tryget_live(&mddev->active_io))
+			goto check_suspended;
+	}
+	if (!mddev->pers->make_request(mddev, bio)) {
+		percpu_ref_put(&mddev->active_io);
+		if (mddev_is_dm(mddev) && mddev->pers->prepare_suspend)
+			return false;
+		goto check_suspended;
+	}
+
+	percpu_ref_put(&mddev->active_io);
+	return true;
+}
+EXPORT_SYMBOL(md_handle_request);
+
+static void md_submit_bio(struct bio *bio)
+{
+	const int rw = bio_data_dir(bio);
+	struct mddev *mddev = bio->bi_bdev->bd_disk->private_data;
+
+	if (mddev == NULL || mddev->pers == NULL) {
+		bio_io_error(bio);
+		return;
+	}
+
+	if (unlikely(test_bit(MD_BROKEN, &mddev->flags)) && (rw == WRITE)) {
+		bio_io_error(bio);
+		return;
+	}
+
+	bio = bio_split_to_limits(bio);
+	if (!bio)
+		return;
+
+	if (mddev->ro == MD_RDONLY && unlikely(rw == WRITE)) {
+		if (bio_sectors(bio) != 0)
+			bio->bi_status = BLK_STS_IOERR;
+		bio_endio(bio);
+		return;
+	}
+
+	/* bio could be mergeable after passing to underlayer */
+	bio->bi_opf &= ~REQ_NOMERGE;
+
+	md_handle_request(mddev, bio);
+}
+
+/*
+ * Make sure no new requests are submitted to the device, and any requests that
+ * have been submitted are completely handled.
+ */
+int mddev_suspend(struct mddev *mddev, bool interruptible)
+{
+	int err = 0;
+
+	/*
+	 * hold reconfig_mutex to wait for normal io will deadlock, because
+	 * other context can't update super_block, and normal io can rely on
+	 * updating super_block.
+	 */
+	lockdep_assert_not_held(&mddev->reconfig_mutex);
+
+	if (interruptible)
+		err = mutex_lock_interruptible(&mddev->suspend_mutex);
+	else
+		mutex_lock(&mddev->suspend_mutex);
+	if (err)
+		return err;
+
+	if (mddev->suspended) {
+		WRITE_ONCE(mddev->suspended, mddev->suspended + 1);
+		mutex_unlock(&mddev->suspend_mutex);
+		return 0;
+	}
+
+	percpu_ref_kill(&mddev->active_io);
+
+	/*
+	 * RAID456 IO can sleep in wait_for_reshape while still holding an
+	 * active_io reference. If reshape is already interrupted or frozen,
+	 * wake those waiters so they can abort and drop the reference instead
+	 * of deadlocking suspend.
+	 */
+	if (mddev->pers && mddev->pers->prepare_suspend &&
+	    reshape_interrupted(mddev))
+		mddev->pers->prepare_suspend(mddev);
+
+	if (interruptible)
+		err = wait_event_interruptible(mddev->sb_wait,
+				percpu_ref_is_zero(&mddev->active_io));
+	else
+		wait_event(mddev->sb_wait,
+				percpu_ref_is_zero(&mddev->active_io));
+	if (err) {
+		percpu_ref_resurrect(&mddev->active_io);
+		mutex_unlock(&mddev->suspend_mutex);
+		return err;
+	}
+
+	/*
+	 * For raid456, io might be waiting for reshape to make progress,
+	 * allow new reshape to start while waiting for io to be done to
+	 * prevent deadlock.
+	 */
+	WRITE_ONCE(mddev->suspended, mddev->suspended + 1);
+
+	mutex_unlock(&mddev->suspend_mutex);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(mddev_suspend);
+
+static void __mddev_resume(struct mddev *mddev, bool recovery_needed)
+{
+	lockdep_assert_not_held(&mddev->reconfig_mutex);
+
+	mutex_lock(&mddev->suspend_mutex);
+	WRITE_ONCE(mddev->suspended, mddev->suspended - 1);
+	if (mddev->suspended) {
+		mutex_unlock(&mddev->suspend_mutex);
+		return;
+	}
+
+	percpu_ref_resurrect(&mddev->active_io);
+	wake_up(&mddev->sb_wait);
+
+	if (recovery_needed)
+		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	md_wakeup_thread(mddev->thread);
+	md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */
+
+	mutex_unlock(&mddev->suspend_mutex);
+}
+
+void mddev_resume(struct mddev *mddev)
+{
+	return __mddev_resume(mddev, true);
+}
+EXPORT_SYMBOL_GPL(mddev_resume);
+
+/* sync bdev before setting device to readonly or stopping raid*/
+static int mddev_set_closing_and_sync_blockdev(struct mddev *mddev, int opener_num)
+{
+	mutex_lock(&mddev->open_mutex);
+	if (mddev->pers && atomic_read(&mddev->openers) > opener_num) {
+		mutex_unlock(&mddev->open_mutex);
+		return -EBUSY;
+	}
+	if (test_and_set_bit(MD_CLOSING, &mddev->flags)) {
+		mutex_unlock(&mddev->open_mutex);
+		return -EBUSY;
+	}
+	mutex_unlock(&mddev->open_mutex);
+
+	sync_blockdev(mddev->gendisk->part0);
+	return 0;
+}
+
+/*
+ * The only difference from bio_chain_endio() is that the current
+ * bi_status of bio does not affect the bi_status of parent.
+ */
+static void md_end_flush(struct bio *bio)
+{
+	struct bio *parent = bio->bi_private;
+
+	/*
+	 * If any flush io error before the power failure,
+	 * disk data may be lost.
+	 */
+	if (bio->bi_status)
+		pr_err("md: %pg flush io error %d\n", bio->bi_bdev,
+			blk_status_to_errno(bio->bi_status));
+
+	bio_put(bio);
+	bio_endio(parent);
+}
+
+bool md_flush_request(struct mddev *mddev, struct bio *bio)
+{
+	struct md_rdev *rdev;
+	struct bio *new;
+
+	/*
+	 * md_flush_reqeust() should be called under md_handle_request() and
+	 * 'active_io' is already grabbed. Hence it's safe to get rdev directly
+	 * without rcu protection.
+	 */
+	WARN_ON(percpu_ref_is_zero(&mddev->active_io));
+
+	rdev_for_each(rdev, mddev) {
+		if (rdev->raid_disk < 0 || test_bit(Faulty, &rdev->flags))
+			continue;
+
+		new = bio_alloc_bioset(rdev->bdev, 0,
+				       REQ_OP_WRITE | REQ_PREFLUSH, GFP_NOIO,
+				       &mddev->bio_set);
+		new->bi_private = bio;
+		new->bi_end_io = md_end_flush;
+		bio_inc_remaining(bio);
+		submit_bio(new);
+	}
+
+	if (bio_sectors(bio) == 0) {
+		bio_endio(bio);
+		return true;
+	}
+
+	bio->bi_opf &= ~REQ_PREFLUSH;
+	return false;
+}
+EXPORT_SYMBOL(md_flush_request);
+
+static inline struct mddev *mddev_get(struct mddev *mddev)
+{
+	lockdep_assert_held(&all_mddevs_lock);
+
+	if (test_bit(MD_DELETED, &mddev->flags))
+		return NULL;
+	atomic_inc(&mddev->active);
+	return mddev;
+}
+
+static void mddev_delayed_delete(struct work_struct *ws);
+
+static void __mddev_put(struct mddev *mddev)
+{
+	if (mddev->raid_disks || !list_empty(&mddev->disks) ||
+	    mddev->ctime || mddev->hold_active)
+		return;
+
+	/*
+	 * If array is freed by stopping array, MD_DELETED is set by
+	 * do_md_stop(), MD_DELETED is still set here in case mddev is freed
+	 * directly by closing a mddev that is created by create_on_open.
+	 */
+	set_bit(MD_DELETED, &mddev->flags);
+	/*
+	 * Call queue_work inside the spinlock so that flush_workqueue() after
+	 * mddev_find will succeed in waiting for the work to be done.
+	 */
+	queue_work(md_misc_wq, &mddev->del_work);
+}
+
+static void mddev_put_locked(struct mddev *mddev)
+{
+	if (atomic_dec_and_test(&mddev->active))
+		__mddev_put(mddev);
+}
+
+void mddev_put(struct mddev *mddev)
+{
+	if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
+		return;
+
+	__mddev_put(mddev);
+	spin_unlock(&all_mddevs_lock);
+}
+
+static void md_safemode_timeout(struct timer_list *t);
+static void md_start_sync(struct work_struct *ws);
+
+static void active_io_release(struct percpu_ref *ref)
+{
+	struct mddev *mddev = container_of(ref, struct mddev, active_io);
+
+	wake_up(&mddev->sb_wait);
+}
+
+static void no_op(struct percpu_ref *r) {}
+
+static void md_bitmap_sysfs_add(struct mddev *mddev)
+{
+	if (sysfs_update_groups(&mddev->kobj, mddev->bitmap_ops->groups))
+		pr_warn("md: cannot register extra bitmap attributes for %s\n",
+			mdname(mddev));
+	else
+		/*
+		 * Inform user with KOBJ_CHANGE about new bitmap
+		 * attributes.
+		 */
+		kobject_uevent(&mddev->kobj, KOBJ_CHANGE);
+}
+
+static void md_bitmap_sysfs_del(struct mddev *mddev)
+{
+	int nr_groups = 0;
+
+	for (nr_groups = 0; mddev->bitmap_ops->groups[nr_groups]; nr_groups++)
+		;
+
+	while (--nr_groups >= 1)
+		sysfs_unmerge_group(&mddev->kobj,
+				    mddev->bitmap_ops->groups[nr_groups]);
+	sysfs_remove_group(&mddev->kobj, mddev->bitmap_ops->groups[0]);
+}
+
+bool mddev_set_bitmap_ops_nosysfs(struct mddev *mddev)
+{
+	struct md_submodule_head *head;
+
+	if (mddev->bitmap_ops &&
+	    mddev->bitmap_ops->head.id == mddev->bitmap_id)
+		return true;
+
+	xa_lock(&md_submodule);
+	head = xa_load(&md_submodule, mddev->bitmap_id);
+
+	if (!head) {
+		pr_warn("md: can't find bitmap id %d\n", mddev->bitmap_id);
+		goto err;
+	}
+
+	if (head->type != MD_BITMAP) {
+		pr_warn("md: invalid bitmap id %d\n", mddev->bitmap_id);
+		goto err;
+	}
+
+	mddev->bitmap_ops = (void *)head;
+	xa_unlock(&md_submodule);
+	return true;
+
+err:
+	xa_unlock(&md_submodule);
+	return false;
+}
+
+int mddev_init(struct mddev *mddev)
+{
+	int err = 0;
+
+	if (!IS_ENABLED(CONFIG_MD_BITMAP))
+		mddev->bitmap_id = ID_BITMAP_NONE;
+	else
+		mddev->bitmap_id = ID_BITMAP;
+
+	if (percpu_ref_init(&mddev->active_io, active_io_release,
+			    PERCPU_REF_ALLOW_REINIT, GFP_KERNEL))
+		return -ENOMEM;
+
+	if (percpu_ref_init(&mddev->writes_pending, no_op,
+			    PERCPU_REF_ALLOW_REINIT, GFP_KERNEL)) {
+		err = -ENOMEM;
+		goto exit_acitve_io;
+	}
+
+	err = bioset_init(&mddev->bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
+	if (err)
+		goto exit_writes_pending;
+
+	err = bioset_init(&mddev->sync_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
+	if (err)
+		goto exit_bio_set;
+
+	err = bioset_init(&mddev->io_clone_set, BIO_POOL_SIZE,
+			  offsetof(struct md_io_clone, bio_clone), 0);
+	if (err)
+		goto exit_sync_set;
+
+	/* We want to start with the refcount at zero */
+	percpu_ref_put(&mddev->writes_pending);
+
+	mutex_init(&mddev->open_mutex);
+	mutex_init(&mddev->reconfig_mutex);
+	mutex_init(&mddev->suspend_mutex);
+	mutex_init(&mddev->bitmap_info.mutex);
+	INIT_LIST_HEAD(&mddev->disks);
+	INIT_LIST_HEAD(&mddev->all_mddevs);
+	INIT_LIST_HEAD(&mddev->deleting);
+	timer_setup(&mddev->safemode_timer, md_safemode_timeout, 0);
+	atomic_set(&mddev->active, 1);
+	atomic_set(&mddev->openers, 0);
+	atomic_set(&mddev->sync_seq, 0);
+	spin_lock_init(&mddev->lock);
+	init_waitqueue_head(&mddev->sb_wait);
+	init_waitqueue_head(&mddev->recovery_wait);
+	mddev->reshape_position = MaxSector;
+	mddev->reshape_backwards = 0;
+	mddev->last_sync_action = ACTION_IDLE;
+	mddev->resync_min = 0;
+	mddev->resync_max = MaxSector;
+	mddev->level = LEVEL_NONE;
+
+	INIT_WORK(&mddev->sync_work, md_start_sync);
+	INIT_WORK(&mddev->del_work, mddev_delayed_delete);
+
+	return 0;
+
+exit_sync_set:
+	bioset_exit(&mddev->sync_set);
+exit_bio_set:
+	bioset_exit(&mddev->bio_set);
+exit_writes_pending:
+	percpu_ref_exit(&mddev->writes_pending);
+exit_acitve_io:
+	percpu_ref_exit(&mddev->active_io);
+	return err;
+}
+EXPORT_SYMBOL_GPL(mddev_init);
+
+void mddev_destroy(struct mddev *mddev)
+{
+	bioset_exit(&mddev->bio_set);
+	bioset_exit(&mddev->sync_set);
+	bioset_exit(&mddev->io_clone_set);
+	percpu_ref_exit(&mddev->active_io);
+	percpu_ref_exit(&mddev->writes_pending);
+}
+EXPORT_SYMBOL_GPL(mddev_destroy);
+
+static struct mddev *mddev_find_locked(dev_t unit)
+{
+	struct mddev *mddev;
+
+	list_for_each_entry(mddev, &all_mddevs, all_mddevs)
+		if (mddev->unit == unit)
+			return mddev;
+
+	return NULL;
+}
+
+/* find an unused unit number */
+static dev_t mddev_alloc_unit(void)
+{
+	static int next_minor = 512;
+	int start = next_minor;
+	bool is_free = 0;
+	dev_t dev = 0;
+
+	while (!is_free) {
+		dev = MKDEV(MD_MAJOR, next_minor);
+		next_minor++;
+		if (next_minor > MINORMASK)
+			next_minor = 0;
+		if (next_minor == start)
+			return 0;		/* Oh dear, all in use. */
+		is_free = !mddev_find_locked(dev);
+	}
+
+	return dev;
+}
+
+static struct mddev *mddev_alloc(dev_t unit)
+{
+	struct mddev *new;
+	int error;
+
+	if (unit && MAJOR(unit) != MD_MAJOR)
+		unit &= ~((1 << MdpMinorShift) - 1);
+
+	new = kzalloc_obj(*new);
+	if (!new)
+		return ERR_PTR(-ENOMEM);
+
+	error = mddev_init(new);
+	if (error)
+		goto out_free_new;
+
+	spin_lock(&all_mddevs_lock);
+	if (unit) {
+		error = -EEXIST;
+		if (mddev_find_locked(unit))
+			goto out_destroy_new;
+		new->unit = unit;
+		if (MAJOR(unit) == MD_MAJOR)
+			new->md_minor = MINOR(unit);
+		else
+			new->md_minor = MINOR(unit) >> MdpMinorShift;
+		new->hold_active = UNTIL_IOCTL;
+	} else {
+		error = -ENODEV;
+		new->unit = mddev_alloc_unit();
+		if (!new->unit)
+			goto out_destroy_new;
+		new->md_minor = MINOR(new->unit);
+		new->hold_active = UNTIL_STOP;
+	}
+
+	list_add(&new->all_mddevs, &all_mddevs);
+	spin_unlock(&all_mddevs_lock);
+	return new;
+
+out_destroy_new:
+	spin_unlock(&all_mddevs_lock);
+	mddev_destroy(new);
+out_free_new:
+	kfree(new);
+	return ERR_PTR(error);
+}
+
+static void mddev_free(struct mddev *mddev)
+{
+	spin_lock(&all_mddevs_lock);
+	list_del(&mddev->all_mddevs);
+	spin_unlock(&all_mddevs_lock);
+
+	mddev_destroy(mddev);
+	kfree(mddev);
+}
+
+static const struct attribute_group md_redundancy_group;
+
+void mddev_unlock(struct mddev *mddev)
+{
+	struct md_rdev *rdev;
+	struct md_rdev *tmp;
+	LIST_HEAD(delete);
+
+	if (!list_empty(&mddev->deleting))
+		list_splice_init(&mddev->deleting, &delete);
+
+	if (mddev->to_remove) {
+		/* These cannot be removed under reconfig_mutex as
+		 * an access to the files will try to take reconfig_mutex
+		 * while holding the file unremovable, which leads to
+		 * a deadlock.
+		 * So hold set sysfs_active while the remove in happeing,
+		 * and anything else which might set ->to_remove or my
+		 * otherwise change the sysfs namespace will fail with
+		 * -EBUSY if sysfs_active is still set.
+		 * We set sysfs_active under reconfig_mutex and elsewhere
+		 * test it under the same mutex to ensure its correct value
+		 * is seen.
+		 */
+		const struct attribute_group *to_remove = mddev->to_remove;
+		mddev->to_remove = NULL;
+		mddev->sysfs_active = 1;
+		mutex_unlock(&mddev->reconfig_mutex);
+
+		if (mddev->kobj.sd) {
+			if (to_remove != &md_redundancy_group)
+				sysfs_remove_group(&mddev->kobj, to_remove);
+			if (mddev->pers == NULL ||
+			    mddev->pers->sync_request == NULL) {
+				sysfs_remove_group(&mddev->kobj, &md_redundancy_group);
+				if (mddev->sysfs_action)
+					sysfs_put(mddev->sysfs_action);
+				if (mddev->sysfs_completed)
+					sysfs_put(mddev->sysfs_completed);
+				if (mddev->sysfs_degraded)
+					sysfs_put(mddev->sysfs_degraded);
+				mddev->sysfs_action = NULL;
+				mddev->sysfs_completed = NULL;
+				mddev->sysfs_degraded = NULL;
+			}
+		}
+		mddev->sysfs_active = 0;
+	} else
+		mutex_unlock(&mddev->reconfig_mutex);
+
+	md_wakeup_thread(mddev->thread);
+	wake_up(&mddev->sb_wait);
+
+	list_for_each_entry_safe(rdev, tmp, &delete, same_set) {
+		list_del_init(&rdev->same_set);
+		kobject_del(&rdev->kobj);
+		export_rdev(rdev);
+	}
+
+	if (!legacy_async_del_gendisk) {
+		/*
+		 * Call del_gendisk after release reconfig_mutex to avoid
+		 * deadlock (e.g. call del_gendisk under the lock and an
+		 * access to sysfs files waits the lock)
+		 * And MD_DELETED is only used for md raid which is set in
+		 * do_md_stop. dm raid only uses md_stop to stop. So dm raid
+		 * doesn't need to check MD_DELETED when getting reconfig lock
+		 */
+		if (test_bit(MD_DELETED, &mddev->flags) &&
+		    !test_and_set_bit(MD_DO_DELETE, &mddev->flags)) {
+			kobject_del(&mddev->kobj);
+			del_gendisk(mddev->gendisk);
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(mddev_unlock);
+
+struct md_rdev *md_find_rdev_nr_rcu(struct mddev *mddev, int nr)
+{
+	struct md_rdev *rdev;
+
+	rdev_for_each_rcu(rdev, mddev)
+		if (rdev->desc_nr == nr)
+			return rdev;
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(md_find_rdev_nr_rcu);
+
+static struct md_rdev *find_rdev(struct mddev *mddev, dev_t dev)
+{
+	struct md_rdev *rdev;
+
+	rdev_for_each(rdev, mddev)
+		if (rdev->bdev->bd_dev == dev)
+			return rdev;
+
+	return NULL;
+}
+
+struct md_rdev *md_find_rdev_rcu(struct mddev *mddev, dev_t dev)
+{
+	struct md_rdev *rdev;
+
+	rdev_for_each_rcu(rdev, mddev)
+		if (rdev->bdev->bd_dev == dev)
+			return rdev;
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(md_find_rdev_rcu);
+
+static struct md_personality *get_pers(int level, char *clevel)
+{
+	struct md_personality *ret = NULL;
+	struct md_submodule_head *head;
+	unsigned long i;
+
+	xa_lock(&md_submodule);
+	xa_for_each(&md_submodule, i, head) {
+		if (head->type != MD_PERSONALITY)
+			continue;
+		if ((level != LEVEL_NONE && head->id == level) ||
+		    !strcmp(head->name, clevel)) {
+			if (try_module_get(head->owner))
+				ret = (void *)head;
+			break;
+		}
+	}
+	xa_unlock(&md_submodule);
+
+	if (!ret) {
+		if (level != LEVEL_NONE)
+			pr_warn("md: personality for level %d is not loaded!\n",
+				level);
+		else
+			pr_warn("md: personality for level %s is not loaded!\n",
+				clevel);
+	}
+
+	return ret;
+}
+
+static void put_pers(struct md_personality *pers)
+{
+	module_put(pers->head.owner);
+}
+
+/* return the offset of the super block in 512byte sectors */
+static inline sector_t calc_dev_sboffset(struct md_rdev *rdev)
+{
+	return MD_NEW_SIZE_SECTORS(bdev_nr_sectors(rdev->bdev));
+}
+
+static int alloc_disk_sb(struct md_rdev *rdev)
+{
+	rdev->sb_page = alloc_page(GFP_KERNEL);
+	if (!rdev->sb_page)
+		return -ENOMEM;
+	return 0;
+}
+
+void md_rdev_clear(struct md_rdev *rdev)
+{
+	if (rdev->sb_page) {
+		put_page(rdev->sb_page);
+		rdev->sb_loaded = 0;
+		rdev->sb_page = NULL;
+		rdev->sb_start = 0;
+		rdev->sectors = 0;
+	}
+	if (rdev->bb_page) {
+		put_page(rdev->bb_page);
+		rdev->bb_page = NULL;
+	}
+	badblocks_exit(&rdev->badblocks);
+}
+EXPORT_SYMBOL_GPL(md_rdev_clear);
+
+static void super_written(struct bio *bio)
+{
+	struct md_rdev *rdev = bio->bi_private;
+	struct mddev *mddev = rdev->mddev;
+
+	if (bio->bi_status) {
+		pr_err("md: %s gets error=%d\n", __func__,
+		       blk_status_to_errno(bio->bi_status));
+		md_error(mddev, rdev);
+		if (!test_bit(Faulty, &rdev->flags)
+		    && (bio->bi_opf & MD_FAILFAST)) {
+			set_bit(MD_SB_NEED_REWRITE, &mddev->sb_flags);
+			set_bit(LastDev, &rdev->flags);
+		}
+	} else
+		clear_bit(LastDev, &rdev->flags);
+
+	bio_put(bio);
+
+	rdev_dec_pending(rdev, mddev);
+
+	if (atomic_dec_and_test(&mddev->pending_writes))
+		wake_up(&mddev->sb_wait);
+}
+
+/**
+ * md_write_metadata - write metadata to underlying disk, including
+ * array superblock, badblocks, bitmap superblock and bitmap bits.
+ * @mddev:	the array to write
+ * @rdev:	the underlying disk to write
+ * @sector:	the offset to @rdev
+ * @size:	the length of the metadata
+ * @page:	the metadata
+ * @offset:	the offset to @page
+ *
+ * Write @size bytes of @page start from @offset, to @sector of @rdev, Increment
+ * mddev->pending_writes before returning, and decrement it on completion,
+ * waking up sb_wait. Caller must call md_super_wait() after issuing io to all
+ * rdev. If an error occurred, md_error() will be called, and the @rdev will be
+ * kicked out from @mddev.
+ */
+void md_write_metadata(struct mddev *mddev, struct md_rdev *rdev,
+		       sector_t sector, int size, struct page *page,
+		       unsigned int offset)
+{
+	struct bio *bio;
+
+	if (!page)
+		return;
+
+	if (test_bit(Faulty, &rdev->flags))
+		return;
+
+	bio = bio_alloc_bioset(rdev->meta_bdev ? rdev->meta_bdev : rdev->bdev,
+			      1,
+			      REQ_OP_WRITE | REQ_SYNC | REQ_IDLE | REQ_META
+				  | REQ_PREFLUSH | REQ_FUA,
+			      GFP_NOIO, &mddev->sync_set);
+
+	atomic_inc(&rdev->nr_pending);
+
+	bio->bi_iter.bi_sector = sector;
+	__bio_add_page(bio, page, size, offset);
+	bio->bi_private = rdev;
+	bio->bi_end_io = super_written;
+
+	if (test_bit(MD_FAILFAST_SUPPORTED, &mddev->flags) &&
+	    test_bit(FailFast, &rdev->flags) &&
+	    !test_bit(LastDev, &rdev->flags))
+		bio->bi_opf |= MD_FAILFAST;
+
+	atomic_inc(&mddev->pending_writes);
+	submit_bio(bio);
+}
+
+int md_super_wait(struct mddev *mddev)
+{
+	/* wait for all superblock writes that were scheduled to complete */
+	wait_event(mddev->sb_wait, atomic_read(&mddev->pending_writes)==0);
+	if (test_and_clear_bit(MD_SB_NEED_REWRITE, &mddev->sb_flags))
+		return -EAGAIN;
+	return 0;
+}
+
+int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
+		 struct page *page, blk_opf_t opf, bool metadata_op)
+{
+	struct bio bio;
+	struct bio_vec bvec;
+
+	if (metadata_op && rdev->meta_bdev)
+		bio_init(&bio, rdev->meta_bdev, &bvec, 1, opf);
+	else
+		bio_init(&bio, rdev->bdev, &bvec, 1, opf);
+
+	if (metadata_op)
+		bio.bi_iter.bi_sector = sector + rdev->sb_start;
+	else if (rdev->mddev->reshape_position != MaxSector &&
+		 (rdev->mddev->reshape_backwards ==
+		  (sector >= rdev->mddev->reshape_position)))
+		bio.bi_iter.bi_sector = sector + rdev->new_data_offset;
+	else
+		bio.bi_iter.bi_sector = sector + rdev->data_offset;
+	__bio_add_page(&bio, page, size, 0);
+
+	submit_bio_wait(&bio);
+
+	return !bio.bi_status;
+}
+EXPORT_SYMBOL_GPL(sync_page_io);
+
+static int read_disk_sb(struct md_rdev *rdev, int size)
+{
+	if (rdev->sb_loaded)
+		return 0;
+
+	if (!sync_page_io(rdev, 0, size, rdev->sb_page, REQ_OP_READ, true))
+		goto fail;
+	rdev->sb_loaded = 1;
+	return 0;
+
+fail:
+	pr_err("md: disabled device %pg, could not read superblock.\n",
+	       rdev->bdev);
+	return -EINVAL;
+}
+
+static int md_uuid_equal(mdp_super_t *sb1, mdp_super_t *sb2)
+{
+	return	sb1->set_uuid0 == sb2->set_uuid0 &&
+		sb1->set_uuid1 == sb2->set_uuid1 &&
+		sb1->set_uuid2 == sb2->set_uuid2 &&
+		sb1->set_uuid3 == sb2->set_uuid3;
+}
+
+static int md_sb_equal(mdp_super_t *sb1, mdp_super_t *sb2)
+{
+	int ret;
+	mdp_super_t *tmp1, *tmp2;
+
+	tmp1 = kmalloc_obj(*tmp1);
+	tmp2 = kmalloc_obj(*tmp2);
+
+	if (!tmp1 || !tmp2) {
+		ret = 0;
+		goto abort;
+	}
+
+	*tmp1 = *sb1;
+	*tmp2 = *sb2;
+
+	/*
+	 * nr_disks is not constant
+	 */
+	tmp1->nr_disks = 0;
+	tmp2->nr_disks = 0;
+
+	ret = (memcmp(tmp1, tmp2, MD_SB_GENERIC_CONSTANT_WORDS * 4) == 0);
+abort:
+	kfree(tmp1);
+	kfree(tmp2);
+	return ret;
+}
+
+static u32 md_csum_fold(u32 csum)
+{
+	csum = (csum & 0xffff) + (csum >> 16);
+	return (csum & 0xffff) + (csum >> 16);
+}
+
+static unsigned int calc_sb_csum(mdp_super_t *sb)
+{
+	u64 newcsum = 0;
+	u32 *sb32 = (u32*)sb;
+	int i;
+	unsigned int disk_csum, csum;
+
+	disk_csum = sb->sb_csum;
+	sb->sb_csum = 0;
+
+	for (i = 0; i < MD_SB_BYTES/4 ; i++)
+		newcsum += sb32[i];
+	csum = (newcsum & 0xffffffff) + (newcsum>>32);
+
+#ifdef CONFIG_ALPHA
+	/* This used to use csum_partial, which was wrong for several
+	 * reasons including that different results are returned on
+	 * different architectures.  It isn't critical that we get exactly
+	 * the same return value as before (we always csum_fold before
+	 * testing, and that removes any differences).  However as we
+	 * know that csum_partial always returned a 16bit value on
+	 * alphas, do a fold to maximise conformity to previous behaviour.
+	 */
+	sb->sb_csum = md_csum_fold(disk_csum);
+#else
+	sb->sb_csum = disk_csum;
+#endif
+	return csum;
+}
+
+/*
+ * Handle superblock details.
+ * We want to be able to handle multiple superblock formats
+ * so we have a common interface to them all, and an array of
+ * different handlers.
+ * We rely on user-space to write the initial superblock, and support
+ * reading and updating of superblocks.
+ * Interface methods are:
+ *   int load_super(struct md_rdev *dev, struct md_rdev *refdev, int minor_version)
+ *      loads and validates a superblock on dev.
+ *      if refdev != NULL, compare superblocks on both devices
+ *    Return:
+ *      0 - dev has a superblock that is compatible with refdev
+ *      1 - dev has a superblock that is compatible and newer than refdev
+ *          so dev should be used as the refdev in future
+ *     -EINVAL superblock incompatible or invalid
+ *     -othererror e.g. -EIO
+ *
+ *   int validate_super(struct mddev *mddev, struct md_rdev *dev)
+ *      Verify that dev is acceptable into mddev.
+ *       The first time, mddev->raid_disks will be 0, and data from
+ *       dev should be merged in.  Subsequent calls check that dev
+ *       is new enough.  Return 0 or -EINVAL
+ *
+ *   void sync_super(struct mddev *mddev, struct md_rdev *dev)
+ *     Update the superblock for rdev with data in mddev
+ *     This does not write to disc.
+ *
+ */
+
+struct super_type  {
+	char		    *name;
+	struct module	    *owner;
+	int		    (*load_super)(struct md_rdev *rdev,
+					  struct md_rdev *refdev,
+					  int minor_version);
+	int		    (*validate_super)(struct mddev *mddev,
+					      struct md_rdev *freshest,
+					      struct md_rdev *rdev);
+	void		    (*sync_super)(struct mddev *mddev,
+					  struct md_rdev *rdev);
+	unsigned long long  (*rdev_size_change)(struct md_rdev *rdev,
+						sector_t num_sectors);
+	int		    (*allow_new_offset)(struct md_rdev *rdev,
+						unsigned long long new_offset);
+};
+
+/*
+ * Check that the given mddev has no bitmap.
+ *
+ * This function is called from the run method of all personalities that do not
+ * support bitmaps. It prints an error message and returns non-zero if mddev
+ * has a bitmap. Otherwise, it returns 0.
+ *
+ */
+int md_check_no_bitmap(struct mddev *mddev)
+{
+	if (!mddev->bitmap_info.file && !mddev->bitmap_info.offset)
+		return 0;
+	pr_warn("%s: bitmaps are not supported for %s\n",
+		mdname(mddev), mddev->pers->head.name);
+	return 1;
+}
+EXPORT_SYMBOL(md_check_no_bitmap);
+
+/*
+ * load_super for 0.90.0
+ */
+static int super_90_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_version)
+{
+	mdp_super_t *sb;
+	int ret;
+	bool spare_disk = true;
+
+	/*
+	 * Calculate the position of the superblock (512byte sectors),
+	 * it's at the end of the disk.
+	 *
+	 * It also happens to be a multiple of 4Kb.
+	 */
+	rdev->sb_start = calc_dev_sboffset(rdev);
+
+	ret = read_disk_sb(rdev, MD_SB_BYTES);
+	if (ret)
+		return ret;
+
+	ret = -EINVAL;
+
+	sb = page_address(rdev->sb_page);
+
+	if (sb->md_magic != MD_SB_MAGIC) {
+		pr_warn("md: invalid raid superblock magic on %pg\n",
+			rdev->bdev);
+		goto abort;
+	}
+
+	if (sb->major_version != 0 ||
+	    sb->minor_version < 90 ||
+	    sb->minor_version > 91) {
+		pr_warn("Bad version number %d.%d on %pg\n",
+			sb->major_version, sb->minor_version, rdev->bdev);
+		goto abort;
+	}
+
+	if (sb->raid_disks <= 0)
+		goto abort;
+
+	if (md_csum_fold(calc_sb_csum(sb)) != md_csum_fold(sb->sb_csum)) {
+		pr_warn("md: invalid superblock checksum on %pg\n", rdev->bdev);
+		goto abort;
+	}
+
+	rdev->preferred_minor = sb->md_minor;
+	rdev->data_offset = 0;
+	rdev->new_data_offset = 0;
+	rdev->sb_size = MD_SB_BYTES;
+	rdev->badblocks.shift = -1;
+
+	rdev->desc_nr = sb->this_disk.number;
+
+	/* not spare disk */
+	if (rdev->desc_nr >= 0 && rdev->desc_nr < MD_SB_DISKS &&
+	    sb->disks[rdev->desc_nr].state & ((1<<MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE)))
+		spare_disk = false;
+
+	if (!refdev) {
+		if (!spare_disk)
+			ret = 1;
+		else
+			ret = 0;
+	} else {
+		__u64 ev1, ev2;
+		mdp_super_t *refsb = page_address(refdev->sb_page);
+		if (!md_uuid_equal(refsb, sb)) {
+			pr_warn("md: %pg has different UUID to %pg\n",
+				rdev->bdev, refdev->bdev);
+			goto abort;
+		}
+		if (!md_sb_equal(refsb, sb)) {
+			pr_warn("md: %pg has same UUID but different superblock to %pg\n",
+				rdev->bdev, refdev->bdev);
+			goto abort;
+		}
+		ev1 = md_event(sb);
+		ev2 = md_event(refsb);
+
+		if (!spare_disk && ev1 > ev2)
+			ret = 1;
+		else
+			ret = 0;
+	}
+	rdev->sectors = rdev->sb_start;
+	/* Limit to 4TB as metadata cannot record more than that.
+	 * (not needed for Linear and RAID0 as metadata doesn't
+	 * record this size)
+	 */
+	if ((u64)rdev->sectors >= (2ULL << 32) && sb->level >= 1)
+		rdev->sectors = (sector_t)(2ULL << 32) - 2;
+
+	if (rdev->sectors < ((sector_t)sb->size) * 2 && sb->level >= 1)
+		/* "this cannot possibly happen" ... */
+		ret = -EINVAL;
+
+ abort:
+	return ret;
+}
+
+static u64 md_bitmap_events_cleared(struct mddev *mddev)
+{
+	struct md_bitmap_stats stats;
+	int err;
+
+	if (!md_bitmap_enabled(mddev, false))
+		return 0;
+
+	err = mddev->bitmap_ops->get_stats(mddev->bitmap, &stats);
+	if (err)
+		return 0;
+
+	return stats.events_cleared;
+}
+
+/*
+ * validate_super for 0.90.0
+ * note: we are not using "freshest" for 0.9 superblock
+ */
+static int super_90_validate(struct mddev *mddev, struct md_rdev *freshest, struct md_rdev *rdev)
+{
+	mdp_disk_t *desc;
+	mdp_super_t *sb = page_address(rdev->sb_page);
+	__u64 ev1 = md_event(sb);
+
+	rdev->raid_disk = -1;
+	clear_bit(Faulty, &rdev->flags);
+	clear_bit(In_sync, &rdev->flags);
+	clear_bit(Bitmap_sync, &rdev->flags);
+	clear_bit(WriteMostly, &rdev->flags);
+
+	if (mddev->raid_disks == 0) {
+		mddev->major_version = 0;
+		mddev->minor_version = sb->minor_version;
+		mddev->patch_version = sb->patch_version;
+		mddev->external = 0;
+		mddev->chunk_sectors = sb->chunk_size >> 9;
+		mddev->ctime = sb->ctime;
+		mddev->utime = sb->utime;
+		mddev->level = sb->level;
+		mddev->clevel[0] = 0;
+		mddev->layout = sb->layout;
+		mddev->raid_disks = sb->raid_disks;
+		mddev->dev_sectors = ((sector_t)sb->size) * 2;
+		mddev->events = ev1;
+		mddev->bitmap_info.offset = 0;
+		mddev->bitmap_info.space = 0;
+		/* bitmap can use 60 K after the 4K superblocks */
+		mddev->bitmap_info.default_offset = MD_SB_BYTES >> 9;
+		mddev->bitmap_info.default_space = 64*2 - (MD_SB_BYTES >> 9);
+		mddev->reshape_backwards = 0;
+
+		if (mddev->minor_version >= 91) {
+			mddev->reshape_position = sb->reshape_position;
+			mddev->delta_disks = sb->delta_disks;
+			mddev->new_level = sb->new_level;
+			mddev->new_layout = sb->new_layout;
+			mddev->new_chunk_sectors = sb->new_chunk >> 9;
+			if (mddev->delta_disks < 0)
+				mddev->reshape_backwards = 1;
+		} else {
+			mddev->reshape_position = MaxSector;
+			mddev->delta_disks = 0;
+			mddev->new_level = mddev->level;
+			mddev->new_layout = mddev->layout;
+			mddev->new_chunk_sectors = mddev->chunk_sectors;
+		}
+		if (mddev->level == 0)
+			mddev->layout = -1;
+
+		if (sb->state & (1<<MD_SB_CLEAN))
+			mddev->resync_offset = MaxSector;
+		else {
+			if (sb->events_hi == sb->cp_events_hi &&
+				sb->events_lo == sb->cp_events_lo) {
+				mddev->resync_offset = sb->recovery_cp;
+			} else
+				mddev->resync_offset = 0;
+		}
+
+		memcpy(mddev->uuid+0, &sb->set_uuid0, 4);
+		memcpy(mddev->uuid+4, &sb->set_uuid1, 4);
+		memcpy(mddev->uuid+8, &sb->set_uuid2, 4);
+		memcpy(mddev->uuid+12,&sb->set_uuid3, 4);
+
+		mddev->max_disks = MD_SB_DISKS;
+
+		if (sb->state & (1<<MD_SB_BITMAP_PRESENT) &&
+		    mddev->bitmap_info.file == NULL) {
+			mddev->bitmap_info.offset =
+				mddev->bitmap_info.default_offset;
+			mddev->bitmap_info.space =
+				mddev->bitmap_info.default_space;
+		}
+
+	} else if (mddev->pers == NULL) {
+		/* Insist on good event counter while assembling, except
+		 * for spares (which don't need an event count) */
+		++ev1;
+		if (sb->disks[rdev->desc_nr].state & (
+			    (1<<MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE)))
+			if (ev1 < mddev->events)
+				return -EINVAL;
+	} else if (mddev->bitmap) {
+		/* if adding to array with a bitmap, then we can accept an
+		 * older device ... but not too old.
+		 */
+		if (ev1 < md_bitmap_events_cleared(mddev))
+			return 0;
+		if (ev1 < mddev->events)
+			set_bit(Bitmap_sync, &rdev->flags);
+	} else {
+		if (ev1 < mddev->events)
+			/* just a hot-add of a new device, leave raid_disk at -1 */
+			return 0;
+	}
+
+	desc = sb->disks + rdev->desc_nr;
+
+	if (desc->state & (1<<MD_DISK_FAULTY))
+		set_bit(Faulty, &rdev->flags);
+	else if (desc->state & (1<<MD_DISK_SYNC)) {
+		set_bit(In_sync, &rdev->flags);
+		rdev->raid_disk = desc->raid_disk;
+		rdev->saved_raid_disk = desc->raid_disk;
+	} else if (desc->state & (1<<MD_DISK_ACTIVE)) {
+		/* active but not in sync implies recovery up to
+		 * reshape position.  We don't know exactly where
+		 * that is, so set to zero for now
+		 */
+		if (mddev->minor_version >= 91) {
+			rdev->recovery_offset = 0;
+			rdev->raid_disk = desc->raid_disk;
+		}
+	}
+	if (desc->state & (1<<MD_DISK_WRITEMOSTLY))
+		set_bit(WriteMostly, &rdev->flags);
+	if (desc->state & (1<<MD_DISK_FAILFAST))
+		set_bit(FailFast, &rdev->flags);
+	return 0;
+}
+
+/*
+ * sync_super for 0.90.0
+ */
+static void super_90_sync(struct mddev *mddev, struct md_rdev *rdev)
+{
+	mdp_super_t *sb;
+	struct md_rdev *rdev2;
+	int next_spare = mddev->raid_disks;
+
+	/* make rdev->sb match mddev data..
+	 *
+	 * 1/ zero out disks
+	 * 2/ Add info for each disk, keeping track of highest desc_nr (next_spare);
+	 * 3/ any empty disks < next_spare become removed
+	 *
+	 * disks[0] gets initialised to REMOVED because
+	 * we cannot be sure from other fields if it has
+	 * been initialised or not.
+	 */
+	int i;
+	int active=0, working=0,failed=0,spare=0,nr_disks=0;
+
+	rdev->sb_size = MD_SB_BYTES;
+
+	sb = page_address(rdev->sb_page);
+
+	memset(sb, 0, sizeof(*sb));
+
+	sb->md_magic = MD_SB_MAGIC;
+	sb->major_version = mddev->major_version;
+	sb->patch_version = mddev->patch_version;
+	sb->gvalid_words  = 0; /* ignored */
+	memcpy(&sb->set_uuid0, mddev->uuid+0, 4);
+	memcpy(&sb->set_uuid1, mddev->uuid+4, 4);
+	memcpy(&sb->set_uuid2, mddev->uuid+8, 4);
+	memcpy(&sb->set_uuid3, mddev->uuid+12,4);
+
+	sb->ctime = clamp_t(time64_t, mddev->ctime, 0, U32_MAX);
+	sb->level = mddev->level;
+	sb->size = mddev->dev_sectors / 2;
+	sb->raid_disks = mddev->raid_disks;
+	sb->md_minor = mddev->md_minor;
+	sb->not_persistent = 0;
+	sb->utime = clamp_t(time64_t, mddev->utime, 0, U32_MAX);
+	sb->state = 0;
+	sb->events_hi = (mddev->events>>32);
+	sb->events_lo = (u32)mddev->events;
+
+	if (mddev->reshape_position == MaxSector)
+		sb->minor_version = 90;
+	else {
+		sb->minor_version = 91;
+		sb->reshape_position = mddev->reshape_position;
+		sb->new_level = mddev->new_level;
+		sb->delta_disks = mddev->delta_disks;
+		sb->new_layout = mddev->new_layout;
+		sb->new_chunk = mddev->new_chunk_sectors << 9;
+	}
+	mddev->minor_version = sb->minor_version;
+	if (mddev->in_sync)
+	{
+		sb->recovery_cp = mddev->resync_offset;
+		sb->cp_events_hi = (mddev->events>>32);
+		sb->cp_events_lo = (u32)mddev->events;
+		if (mddev->resync_offset == MaxSector)
+			sb->state = (1<< MD_SB_CLEAN);
+	} else
+		sb->recovery_cp = 0;
+
+	sb->layout = mddev->layout;
+	sb->chunk_size = mddev->chunk_sectors << 9;
+
+	if (mddev->bitmap && mddev->bitmap_info.file == NULL)
+		sb->state |= (1<<MD_SB_BITMAP_PRESENT);
+
+	sb->disks[0].state = (1<<MD_DISK_REMOVED);
+	rdev_for_each(rdev2, mddev) {
+		mdp_disk_t *d;
+		int desc_nr;
+		int is_active = test_bit(In_sync, &rdev2->flags);
+
+		if (rdev2->raid_disk >= 0 &&
+		    sb->minor_version >= 91)
+			/* we have nowhere to store the recovery_offset,
+			 * but if it is not below the reshape_position,
+			 * we can piggy-back on that.
+			 */
+			is_active = 1;
+		if (rdev2->raid_disk < 0 ||
+		    test_bit(Faulty, &rdev2->flags))
+			is_active = 0;
+		if (is_active)
+			desc_nr = rdev2->raid_disk;
+		else
+			desc_nr = next_spare++;
+		rdev2->desc_nr = desc_nr;
+		d = &sb->disks[rdev2->desc_nr];
+		nr_disks++;
+		d->number = rdev2->desc_nr;
+		d->major = MAJOR(rdev2->bdev->bd_dev);
+		d->minor = MINOR(rdev2->bdev->bd_dev);
+		if (is_active)
+			d->raid_disk = rdev2->raid_disk;
+		else
+			d->raid_disk = rdev2->desc_nr; /* compatibility */
+		if (test_bit(Faulty, &rdev2->flags))
+			d->state = (1<<MD_DISK_FAULTY);
+		else if (is_active) {
+			d->state = (1<<MD_DISK_ACTIVE);
+			if (test_bit(In_sync, &rdev2->flags))
+				d->state |= (1<<MD_DISK_SYNC);
+			active++;
+			working++;
+		} else {
+			d->state = 0;
+			spare++;
+			working++;
+		}
+		if (test_bit(WriteMostly, &rdev2->flags))
+			d->state |= (1<<MD_DISK_WRITEMOSTLY);
+		if (test_bit(FailFast, &rdev2->flags))
+			d->state |= (1<<MD_DISK_FAILFAST);
+	}
+	/* now set the "removed" and "faulty" bits on any missing devices */
+	for (i=0 ; i < mddev->raid_disks ; i++) {
+		mdp_disk_t *d = &sb->disks[i];
+		if (d->state == 0 && d->number == 0) {
+			d->number = i;
+			d->raid_disk = i;
+			d->state = (1<<MD_DISK_REMOVED);
+			d->state |= (1<<MD_DISK_FAULTY);
+			failed++;
+		}
+	}
+	sb->nr_disks = nr_disks;
+	sb->active_disks = active;
+	sb->working_disks = working;
+	sb->failed_disks = failed;
+	sb->spare_disks = spare;
+
+	sb->this_disk = sb->disks[rdev->desc_nr];
+	sb->sb_csum = calc_sb_csum(sb);
+}
+
+/*
+ * rdev_size_change for 0.90.0
+ */
+static unsigned long long
+super_90_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
+{
+	if (num_sectors && num_sectors < rdev->mddev->dev_sectors)
+		return 0; /* component must fit device */
+	if (rdev->mddev->bitmap_info.offset)
+		return 0; /* can't move bitmap */
+	rdev->sb_start = calc_dev_sboffset(rdev);
+	if (!num_sectors || num_sectors > rdev->sb_start)
+		num_sectors = rdev->sb_start;
+	/* Limit to 4TB as metadata cannot record more than that.
+	 * 4TB == 2^32 KB, or 2*2^32 sectors.
+	 */
+	if ((u64)num_sectors >= (2ULL << 32) && rdev->mddev->level >= 1)
+		num_sectors = (sector_t)(2ULL << 32) - 2;
+	do {
+		md_write_metadata(rdev->mddev, rdev, rdev->sb_start,
+				  rdev->sb_size, rdev->sb_page, 0);
+	} while (md_super_wait(rdev->mddev) < 0);
+	return num_sectors;
+}
+
+static int
+super_90_allow_new_offset(struct md_rdev *rdev, unsigned long long new_offset)
+{
+	/* non-zero offset changes not possible with v0.90 */
+	return new_offset == 0;
+}
+
+/*
+ * version 1 superblock
+ */
+
+static __le32 calc_sb_1_csum(struct mdp_superblock_1 *sb)
+{
+	__le32 disk_csum;
+	u32 csum;
+	unsigned long long newcsum;
+	int size = 256 + le32_to_cpu(sb->max_dev)*2;
+	__le32 *isuper = (__le32*)sb;
+
+	disk_csum = sb->sb_csum;
+	sb->sb_csum = 0;
+	newcsum = 0;
+	for (; size >= 4; size -= 4)
+		newcsum += le32_to_cpu(*isuper++);
+
+	if (size == 2)
+		newcsum += le16_to_cpu(*(__le16*) isuper);
+
+	csum = (newcsum & 0xffffffff) + (newcsum >> 32);
+	sb->sb_csum = disk_csum;
+	return cpu_to_le32(csum);
+}
+
+static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_version)
+{
+	struct mdp_superblock_1 *sb;
+	int ret;
+	sector_t sb_start;
+	sector_t sectors;
+	int bmask;
+	bool spare_disk = true;
+
+	/*
+	 * Calculate the position of the superblock in 512byte sectors.
+	 * It is always aligned to a 4K boundary and
+	 * depeding on minor_version, it can be:
+	 * 0: At least 8K, but less than 12K, from end of device
+	 * 1: At start of device
+	 * 2: 4K from start of device.
+	 */
+	switch(minor_version) {
+	case 0:
+		sb_start = bdev_nr_sectors(rdev->bdev) - 8 * 2;
+		sb_start &= ~(sector_t)(4*2-1);
+		break;
+	case 1:
+		sb_start = 0;
+		break;
+	case 2:
+		sb_start = 8;
+		break;
+	default:
+		return -EINVAL;
+	}
+	rdev->sb_start = sb_start;
+
+	/* superblock is rarely larger than 1K, but it can be larger,
+	 * and it is safe to read 4k, so we do that
+	 */
+	ret = read_disk_sb(rdev, 4096);
+	if (ret) return ret;
+
+	sb = page_address(rdev->sb_page);
+
+	if (sb->magic != cpu_to_le32(MD_SB_MAGIC) ||
+	    sb->major_version != cpu_to_le32(1) ||
+	    le32_to_cpu(sb->max_dev) > (4096-256)/2 ||
+	    le64_to_cpu(sb->super_offset) != rdev->sb_start ||
+	    (le32_to_cpu(sb->feature_map) & ~MD_FEATURE_ALL) != 0)
+		return -EINVAL;
+
+	if (calc_sb_1_csum(sb) != sb->sb_csum) {
+		pr_warn("md: invalid superblock checksum on %pg\n",
+			rdev->bdev);
+		return -EINVAL;
+	}
+	if (le64_to_cpu(sb->data_size) < 10) {
+		pr_warn("md: data_size too small on %pg\n",
+			rdev->bdev);
+		return -EINVAL;
+	}
+	if (sb->pad0 ||
+	    sb->pad3[0] ||
+	    memcmp(sb->pad3, sb->pad3+1, sizeof(sb->pad3) - sizeof(sb->pad3[1]))) {
+		pr_warn("Some padding is non-zero on %pg, might be a new feature\n",
+			rdev->bdev);
+		if (check_new_feature)
+			return -EINVAL;
+		pr_warn("check_new_feature is disabled, data corruption possible\n");
+	}
+
+	rdev->preferred_minor = 0xffff;
+	rdev->data_offset = le64_to_cpu(sb->data_offset);
+	rdev->new_data_offset = rdev->data_offset;
+	if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE) &&
+	    (le32_to_cpu(sb->feature_map) & MD_FEATURE_NEW_OFFSET))
+		rdev->new_data_offset += (s32)le32_to_cpu(sb->new_offset);
+	atomic_set(&rdev->corrected_errors, le32_to_cpu(sb->cnt_corrected_read));
+
+	rdev->sb_size = le32_to_cpu(sb->max_dev) * 2 + 256;
+	bmask = queue_logical_block_size(rdev->bdev->bd_disk->queue)-1;
+	if (rdev->sb_size & bmask)
+		rdev->sb_size = (rdev->sb_size | bmask) + 1;
+
+	if (minor_version
+	    && rdev->data_offset < sb_start + (rdev->sb_size/512))
+		return -EINVAL;
+	if (minor_version
+	    && rdev->new_data_offset < sb_start + (rdev->sb_size/512))
+		return -EINVAL;
+
+	rdev->desc_nr = le32_to_cpu(sb->dev_number);
+
+	if (!rdev->bb_page) {
+		rdev->bb_page = alloc_page(GFP_KERNEL);
+		if (!rdev->bb_page)
+			return -ENOMEM;
+	}
+	if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_BAD_BLOCKS) &&
+	    rdev->badblocks.count == 0) {
+		/* need to load the bad block list.
+		 * Currently we limit it to one page.
+		 */
+		s32 offset;
+		sector_t bb_sector;
+		__le64 *bbp;
+		int i;
+		int sectors = le16_to_cpu(sb->bblog_size);
+		if (sectors > (PAGE_SIZE / 512))
+			return -EINVAL;
+		offset = le32_to_cpu(sb->bblog_offset);
+		if (offset == 0)
+			return -EINVAL;
+		bb_sector = (long long)offset;
+		if (!sync_page_io(rdev, bb_sector, sectors << 9,
+				  rdev->bb_page, REQ_OP_READ, true))
+			return -EIO;
+		bbp = (__le64 *)page_address(rdev->bb_page);
+
+		/* check for badblocks api. */
+		if (sb->bblog_shift >= BITS_PER_TYPE(sector_t)) {
+			pr_err("md: %pg: bogus bblog_shift %u for badblocks.\n",
+			       rdev->bdev, sb->bblog_shift);
+			return -EINVAL;
+		}
+		rdev->badblocks.shift = sb->bblog_shift;
+		for (i = 0 ; i < (sectors << (9-3)) ; i++, bbp++) {
+			u64 bb = le64_to_cpu(*bbp);
+			int count = bb & (0x3ff);
+			u64 sector = bb >> 10;
+			sector <<= sb->bblog_shift;
+			count <<= sb->bblog_shift;
+			if (bb + 1 == 0)
+				break;
+			if (!badblocks_set(&rdev->badblocks, sector, count, 1))
+				return -EINVAL;
+		}
+	} else if (sb->bblog_offset != 0)
+		rdev->badblocks.shift = 0;
+
+	if ((le32_to_cpu(sb->feature_map) &
+	    (MD_FEATURE_PPL | MD_FEATURE_MULTIPLE_PPLS))) {
+		rdev->ppl.offset = (__s16)le16_to_cpu(sb->ppl.offset);
+		rdev->ppl.size = le16_to_cpu(sb->ppl.size);
+		rdev->ppl.sector = rdev->sb_start + rdev->ppl.offset;
+	}
+
+	if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RAID0_LAYOUT) &&
+	    sb->level != 0)
+		return -EINVAL;
+
+	/* not spare disk */
+	if (rdev->desc_nr >= 0 && rdev->desc_nr < le32_to_cpu(sb->max_dev) &&
+	    (le16_to_cpu(sb->dev_roles[rdev->desc_nr]) < MD_DISK_ROLE_MAX ||
+	     le16_to_cpu(sb->dev_roles[rdev->desc_nr]) == MD_DISK_ROLE_JOURNAL))
+		spare_disk = false;
+
+	if (!refdev) {
+		if (!spare_disk)
+			ret = 1;
+		else
+			ret = 0;
+	} else {
+		__u64 ev1, ev2;
+		struct mdp_superblock_1 *refsb = page_address(refdev->sb_page);
+
+		if (memcmp(sb->set_uuid, refsb->set_uuid, 16) != 0 ||
+		    sb->level != refsb->level ||
+		    sb->layout != refsb->layout ||
+		    sb->chunksize != refsb->chunksize) {
+			pr_warn("md: %pg has strangely different superblock to %pg\n",
+				rdev->bdev,
+				refdev->bdev);
+			return -EINVAL;
+		}
+		ev1 = le64_to_cpu(sb->events);
+		ev2 = le64_to_cpu(refsb->events);
+
+		if (!spare_disk && ev1 > ev2)
+			ret = 1;
+		else
+			ret = 0;
+	}
+	if (minor_version)
+		sectors = bdev_nr_sectors(rdev->bdev) - rdev->data_offset;
+	else
+		sectors = rdev->sb_start;
+	if (sectors < le64_to_cpu(sb->data_size))
+		return -EINVAL;
+	rdev->sectors = le64_to_cpu(sb->data_size);
+	return ret;
+}
+
+static int super_1_validate(struct mddev *mddev, struct md_rdev *freshest, struct md_rdev *rdev)
+{
+	struct mdp_superblock_1 *sb = page_address(rdev->sb_page);
+	__u64 ev1 = le64_to_cpu(sb->events);
+	int role;
+
+	rdev->raid_disk = -1;
+	clear_bit(Faulty, &rdev->flags);
+	clear_bit(In_sync, &rdev->flags);
+	clear_bit(Bitmap_sync, &rdev->flags);
+	clear_bit(WriteMostly, &rdev->flags);
+
+	if (mddev->raid_disks == 0) {
+		mddev->major_version = 1;
+		mddev->patch_version = 0;
+		mddev->external = 0;
+		mddev->chunk_sectors = le32_to_cpu(sb->chunksize);
+		mddev->ctime = le64_to_cpu(sb->ctime);
+		mddev->utime = le64_to_cpu(sb->utime);
+		mddev->level = le32_to_cpu(sb->level);
+		mddev->clevel[0] = 0;
+		mddev->layout = le32_to_cpu(sb->layout);
+		mddev->raid_disks = le32_to_cpu(sb->raid_disks);
+		mddev->dev_sectors = le64_to_cpu(sb->size);
+		mddev->events = ev1;
+		mddev->bitmap_info.offset = 0;
+		mddev->bitmap_info.space = 0;
+		/* Default location for bitmap is 1K after superblock
+		 * using 3K - total of 4K
+		 */
+		mddev->bitmap_info.default_offset = 1024 >> 9;
+		mddev->bitmap_info.default_space = (4096-1024) >> 9;
+		mddev->reshape_backwards = 0;
+
+		mddev->resync_offset = le64_to_cpu(sb->resync_offset);
+		memcpy(mddev->uuid, sb->set_uuid, 16);
+
+		mddev->max_disks =  (4096-256)/2;
+
+		if (!mddev->logical_block_size)
+			mddev->logical_block_size = le32_to_cpu(sb->logical_block_size);
+
+		if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_BITMAP_OFFSET) &&
+		    mddev->bitmap_info.file == NULL) {
+			mddev->bitmap_info.offset =
+				(__s32)le32_to_cpu(sb->bitmap_offset);
+			/* Metadata doesn't record how much space is available.
+			 * For 1.0, we assume we can use up to the superblock
+			 * if before, else to 4K beyond superblock.
+			 * For others, assume no change is possible.
+			 */
+			if (mddev->minor_version > 0)
+				mddev->bitmap_info.space = 0;
+			else if (mddev->bitmap_info.offset > 0)
+				mddev->bitmap_info.space =
+					8 - mddev->bitmap_info.offset;
+			else
+				mddev->bitmap_info.space =
+					-mddev->bitmap_info.offset;
+		}
+
+		if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE)) {
+			mddev->reshape_position = le64_to_cpu(sb->reshape_position);
+			mddev->delta_disks = le32_to_cpu(sb->delta_disks);
+			mddev->new_level = le32_to_cpu(sb->new_level);
+			mddev->new_layout = le32_to_cpu(sb->new_layout);
+			mddev->new_chunk_sectors = le32_to_cpu(sb->new_chunk);
+			if (mddev->delta_disks < 0 ||
+			    (mddev->delta_disks == 0 &&
+			     (le32_to_cpu(sb->feature_map)
+			      & MD_FEATURE_RESHAPE_BACKWARDS)))
+				mddev->reshape_backwards = 1;
+		} else {
+			mddev->reshape_position = MaxSector;
+			mddev->delta_disks = 0;
+			mddev->new_level = mddev->level;
+			mddev->new_layout = mddev->layout;
+			mddev->new_chunk_sectors = mddev->chunk_sectors;
+		}
+
+		if (mddev->level == 0 &&
+		    !(le32_to_cpu(sb->feature_map) & MD_FEATURE_RAID0_LAYOUT))
+			mddev->layout = -1;
+
+		if (le32_to_cpu(sb->feature_map) & MD_FEATURE_JOURNAL)
+			set_bit(MD_HAS_JOURNAL, &mddev->flags);
+
+		if (le32_to_cpu(sb->feature_map) &
+		    (MD_FEATURE_PPL | MD_FEATURE_MULTIPLE_PPLS)) {
+			if (le32_to_cpu(sb->feature_map) &
+			    (MD_FEATURE_BITMAP_OFFSET | MD_FEATURE_JOURNAL))
+				return -EINVAL;
+			if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_PPL) &&
+			    (le32_to_cpu(sb->feature_map) &
+					    MD_FEATURE_MULTIPLE_PPLS))
+				return -EINVAL;
+			set_bit(MD_HAS_PPL, &mddev->flags);
+		}
+	} else if (mddev->pers == NULL) {
+		/* Insist of good event counter while assembling, except for
+		 * spares (which don't need an event count).
+		 * Similar to mdadm, we allow event counter difference of 1
+		 * from the freshest device.
+		 */
+		if (rdev->desc_nr >= 0 &&
+		    rdev->desc_nr < le32_to_cpu(sb->max_dev) &&
+		    (le16_to_cpu(sb->dev_roles[rdev->desc_nr]) < MD_DISK_ROLE_MAX ||
+		     le16_to_cpu(sb->dev_roles[rdev->desc_nr]) == MD_DISK_ROLE_JOURNAL))
+			if (ev1 + 1 < mddev->events)
+				return -EINVAL;
+	} else if (mddev->bitmap) {
+		/* If adding to array with a bitmap, then we can accept an
+		 * older device, but not too old.
+		 */
+		if (ev1 < md_bitmap_events_cleared(mddev))
+			return 0;
+		if (ev1 < mddev->events)
+			set_bit(Bitmap_sync, &rdev->flags);
+	} else {
+		if (ev1 < mddev->events)
+			/* just a hot-add of a new device, leave raid_disk at -1 */
+			return 0;
+	}
+
+	if (rdev->desc_nr < 0 ||
+	    rdev->desc_nr >= le32_to_cpu(sb->max_dev)) {
+		role = MD_DISK_ROLE_SPARE;
+		rdev->desc_nr = -1;
+	} else if (mddev->pers == NULL && freshest && ev1 < mddev->events) {
+		/*
+		 * If we are assembling, and our event counter is smaller than the
+		 * highest event counter, we cannot trust our superblock about the role.
+		 * It could happen that our rdev was marked as Faulty, and all other
+		 * superblocks were updated with +1 event counter.
+		 * Then, before the next superblock update, which typically happens when
+		 * remove_and_add_spares() removes the device from the array, there was
+		 * a crash or reboot.
+		 * If we allow current rdev without consulting the freshest superblock,
+		 * we could cause data corruption.
+		 * Note that in this case our event counter is smaller by 1 than the
+		 * highest, otherwise, this rdev would not be allowed into array;
+		 * both kernel and mdadm allow event counter difference of 1.
+		 */
+		struct mdp_superblock_1 *freshest_sb = page_address(freshest->sb_page);
+		u32 freshest_max_dev = le32_to_cpu(freshest_sb->max_dev);
+
+		if (rdev->desc_nr >= freshest_max_dev) {
+			/* this is unexpected, better not proceed */
+			pr_warn("md: %s: rdev[%pg]: desc_nr(%d) >= freshest(%pg)->sb->max_dev(%u)\n",
+				mdname(mddev), rdev->bdev, rdev->desc_nr,
+				freshest->bdev, freshest_max_dev);
+			return -EUCLEAN;
+		}
+
+		role = le16_to_cpu(freshest_sb->dev_roles[rdev->desc_nr]);
+		pr_debug("md: %s: rdev[%pg]: role=%d(0x%x) according to freshest %pg\n",
+			 mdname(mddev), rdev->bdev, role, role, freshest->bdev);
+	} else {
+		role = le16_to_cpu(sb->dev_roles[rdev->desc_nr]);
+	}
+	switch (role) {
+	case MD_DISK_ROLE_SPARE: /* spare */
+		break;
+	case MD_DISK_ROLE_FAULTY: /* faulty */
+		set_bit(Faulty, &rdev->flags);
+		break;
+	case MD_DISK_ROLE_JOURNAL: /* journal device */
+		if (!(le32_to_cpu(sb->feature_map) & MD_FEATURE_JOURNAL)) {
+			/* journal device without journal feature */
+			pr_warn("md: journal device provided without journal feature, ignoring the device\n");
+			return -EINVAL;
+		}
+		set_bit(Journal, &rdev->flags);
+		rdev->journal_tail = le64_to_cpu(sb->journal_tail);
+		rdev->raid_disk = 0;
+		break;
+	default:
+		rdev->saved_raid_disk = role;
+		if ((le32_to_cpu(sb->feature_map) &
+		     MD_FEATURE_RECOVERY_OFFSET)) {
+			rdev->recovery_offset = le64_to_cpu(sb->recovery_offset);
+			if (!(le32_to_cpu(sb->feature_map) &
+			      MD_FEATURE_RECOVERY_BITMAP))
+				rdev->saved_raid_disk = -1;
+		} else {
+			/*
+			 * If the array is FROZEN, then the device can't
+			 * be in_sync with rest of array.
+			 */
+			if (!test_bit(MD_RECOVERY_FROZEN,
+				      &mddev->recovery))
+				set_bit(In_sync, &rdev->flags);
+		}
+		rdev->raid_disk = role;
+		break;
+	}
+	if (sb->devflags & WriteMostly1)
+		set_bit(WriteMostly, &rdev->flags);
+	if (sb->devflags & FailFast1)
+		set_bit(FailFast, &rdev->flags);
+	if (le32_to_cpu(sb->feature_map) & MD_FEATURE_REPLACEMENT)
+		set_bit(Replacement, &rdev->flags);
+
+	return 0;
+}
+
+static void super_1_sync(struct mddev *mddev, struct md_rdev *rdev)
+{
+	struct mdp_superblock_1 *sb;
+	struct md_rdev *rdev2;
+	int max_dev, i;
+	/* make rdev->sb match mddev and rdev data. */
+
+	sb = page_address(rdev->sb_page);
+
+	sb->feature_map = 0;
+	sb->pad0 = 0;
+	sb->recovery_offset = cpu_to_le64(0);
+	memset(sb->pad3, 0, sizeof(sb->pad3));
+
+	sb->utime = cpu_to_le64((__u64)mddev->utime);
+	sb->events = cpu_to_le64(mddev->events);
+	if (mddev->in_sync)
+		sb->resync_offset = cpu_to_le64(mddev->resync_offset);
+	else if (test_bit(MD_JOURNAL_CLEAN, &mddev->flags))
+		sb->resync_offset = cpu_to_le64(MaxSector);
+	else
+		sb->resync_offset = cpu_to_le64(0);
+
+	sb->cnt_corrected_read = cpu_to_le32(atomic_read(&rdev->corrected_errors));
+
+	sb->raid_disks = cpu_to_le32(mddev->raid_disks);
+	sb->size = cpu_to_le64(mddev->dev_sectors);
+	sb->chunksize = cpu_to_le32(mddev->chunk_sectors);
+	sb->level = cpu_to_le32(mddev->level);
+	sb->layout = cpu_to_le32(mddev->layout);
+	sb->logical_block_size = cpu_to_le32(mddev->logical_block_size);
+	if (test_bit(FailFast, &rdev->flags))
+		sb->devflags |= FailFast1;
+	else
+		sb->devflags &= ~FailFast1;
+
+	if (test_bit(WriteMostly, &rdev->flags))
+		sb->devflags |= WriteMostly1;
+	else
+		sb->devflags &= ~WriteMostly1;
+	sb->data_offset = cpu_to_le64(rdev->data_offset);
+	sb->data_size = cpu_to_le64(rdev->sectors);
+
+	if (mddev->bitmap && mddev->bitmap_info.file == NULL) {
+		sb->bitmap_offset = cpu_to_le32((__u32)mddev->bitmap_info.offset);
+		sb->feature_map = cpu_to_le32(MD_FEATURE_BITMAP_OFFSET);
+	}
+
+	if (rdev->raid_disk >= 0 && !test_bit(Journal, &rdev->flags) &&
+	    !test_bit(In_sync, &rdev->flags)) {
+		sb->feature_map |=
+			cpu_to_le32(MD_FEATURE_RECOVERY_OFFSET);
+		sb->recovery_offset =
+			cpu_to_le64(rdev->recovery_offset);
+		if (rdev->saved_raid_disk >= 0 && mddev->bitmap)
+			sb->feature_map |=
+				cpu_to_le32(MD_FEATURE_RECOVERY_BITMAP);
+	}
+	/* Note: recovery_offset and journal_tail share space  */
+	if (test_bit(Journal, &rdev->flags))
+		sb->journal_tail = cpu_to_le64(rdev->journal_tail);
+	if (test_bit(Replacement, &rdev->flags))
+		sb->feature_map |=
+			cpu_to_le32(MD_FEATURE_REPLACEMENT);
+
+	if (mddev->reshape_position != MaxSector) {
+		sb->feature_map |= cpu_to_le32(MD_FEATURE_RESHAPE_ACTIVE);
+		sb->reshape_position = cpu_to_le64(mddev->reshape_position);
+		sb->new_layout = cpu_to_le32(mddev->new_layout);
+		sb->delta_disks = cpu_to_le32(mddev->delta_disks);
+		sb->new_level = cpu_to_le32(mddev->new_level);
+		sb->new_chunk = cpu_to_le32(mddev->new_chunk_sectors);
+		if (mddev->delta_disks == 0 &&
+		    mddev->reshape_backwards)
+			sb->feature_map
+				|= cpu_to_le32(MD_FEATURE_RESHAPE_BACKWARDS);
+		if (rdev->new_data_offset != rdev->data_offset) {
+			sb->feature_map
+				|= cpu_to_le32(MD_FEATURE_NEW_OFFSET);
+			sb->new_offset = cpu_to_le32((__u32)(rdev->new_data_offset
+							     - rdev->data_offset));
+		}
+	}
+
+	if (mddev_is_clustered(mddev))
+		sb->feature_map |= cpu_to_le32(MD_FEATURE_CLUSTERED);
+
+	if (rdev->badblocks.count == 0)
+		/* Nothing to do for bad blocks*/ ;
+	else if (sb->bblog_offset == 0)
+		/* Cannot record bad blocks on this device */
+		md_error(mddev, rdev);
+	else {
+		struct badblocks *bb = &rdev->badblocks;
+		__le64 *bbp = (__le64 *)page_address(rdev->bb_page);
+		u64 *p = bb->page;
+		sb->feature_map |= cpu_to_le32(MD_FEATURE_BAD_BLOCKS);
+		if (bb->changed) {
+			unsigned seq;
+
+retry:
+			seq = read_seqbegin(&bb->lock);
+
+			memset(bbp, 0xff, PAGE_SIZE);
+
+			for (i = 0 ; i < bb->count ; i++) {
+				u64 internal_bb = p[i];
+				u64 store_bb = ((BB_OFFSET(internal_bb) << 10)
+						| BB_LEN(internal_bb));
+				bbp[i] = cpu_to_le64(store_bb);
+			}
+			bb->changed = 0;
+			if (read_seqretry(&bb->lock, seq))
+				goto retry;
+
+			bb->sector = (rdev->sb_start +
+				      (int)le32_to_cpu(sb->bblog_offset));
+			bb->size = le16_to_cpu(sb->bblog_size);
+		}
+	}
+
+	max_dev = 0;
+	rdev_for_each(rdev2, mddev)
+		if (rdev2->desc_nr+1 > max_dev)
+			max_dev = rdev2->desc_nr+1;
+
+	if (max_dev > le32_to_cpu(sb->max_dev)) {
+		int bmask;
+		sb->max_dev = cpu_to_le32(max_dev);
+		rdev->sb_size = max_dev * 2 + 256;
+		bmask = queue_logical_block_size(rdev->bdev->bd_disk->queue)-1;
+		if (rdev->sb_size & bmask)
+			rdev->sb_size = (rdev->sb_size | bmask) + 1;
+	} else
+		max_dev = le32_to_cpu(sb->max_dev);
+
+	for (i=0; i<max_dev;i++)
+		sb->dev_roles[i] = cpu_to_le16(MD_DISK_ROLE_SPARE);
+
+	if (test_bit(MD_HAS_JOURNAL, &mddev->flags))
+		sb->feature_map |= cpu_to_le32(MD_FEATURE_JOURNAL);
+
+	if (test_bit(MD_HAS_PPL, &mddev->flags)) {
+		if (test_bit(MD_HAS_MULTIPLE_PPLS, &mddev->flags))
+			sb->feature_map |=
+			    cpu_to_le32(MD_FEATURE_MULTIPLE_PPLS);
+		else
+			sb->feature_map |= cpu_to_le32(MD_FEATURE_PPL);
+		sb->ppl.offset = cpu_to_le16(rdev->ppl.offset);
+		sb->ppl.size = cpu_to_le16(rdev->ppl.size);
+	}
+
+	rdev_for_each(rdev2, mddev) {
+		i = rdev2->desc_nr;
+		if (test_bit(Faulty, &rdev2->flags))
+			sb->dev_roles[i] = cpu_to_le16(MD_DISK_ROLE_FAULTY);
+		else if (test_bit(In_sync, &rdev2->flags))
+			sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
+		else if (test_bit(Journal, &rdev2->flags))
+			sb->dev_roles[i] = cpu_to_le16(MD_DISK_ROLE_JOURNAL);
+		else if (rdev2->raid_disk >= 0)
+			sb->dev_roles[i] = cpu_to_le16(rdev2->raid_disk);
+		else
+			sb->dev_roles[i] = cpu_to_le16(MD_DISK_ROLE_SPARE);
+	}
+
+	sb->sb_csum = calc_sb_1_csum(sb);
+}
+
+static sector_t super_1_choose_bm_space(sector_t dev_size)
+{
+	sector_t bm_space;
+
+	/* if the device is bigger than 8Gig, save 64k for bitmap
+	 * usage, if bigger than 200Gig, save 128k
+	 */
+	if (dev_size < 64*2)
+		bm_space = 0;
+	else if (dev_size - 64*2 >= 200*1024*1024*2)
+		bm_space = 128*2;
+	else if (dev_size - 4*2 > 8*1024*1024*2)
+		bm_space = 64*2;
+	else
+		bm_space = 4*2;
+	return bm_space;
+}
+
+static unsigned long long
+super_1_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
+{
+	struct mdp_superblock_1 *sb;
+	sector_t max_sectors;
+	if (num_sectors && num_sectors < rdev->mddev->dev_sectors)
+		return 0; /* component must fit device */
+	if (rdev->data_offset != rdev->new_data_offset)
+		return 0; /* too confusing */
+	if (rdev->sb_start < rdev->data_offset) {
+		/* minor versions 1 and 2; superblock before data */
+		max_sectors = bdev_nr_sectors(rdev->bdev) - rdev->data_offset;
+		if (!num_sectors || num_sectors > max_sectors)
+			num_sectors = max_sectors;
+	} else if (rdev->mddev->bitmap_info.offset) {
+		/* minor version 0 with bitmap we can't move */
+		return 0;
+	} else {
+		/* minor version 0; superblock after data */
+		sector_t sb_start, bm_space;
+		sector_t dev_size = bdev_nr_sectors(rdev->bdev);
+
+		/* 8K is for superblock */
+		sb_start = dev_size - 8*2;
+		sb_start &= ~(sector_t)(4*2 - 1);
+
+		bm_space = super_1_choose_bm_space(dev_size);
+
+		/* Space that can be used to store date needs to decrease
+		 * superblock bitmap space and bad block space(4K)
+		 */
+		max_sectors = sb_start - bm_space - 4*2;
+
+		if (!num_sectors || num_sectors > max_sectors)
+			num_sectors = max_sectors;
+		rdev->sb_start = sb_start;
+	}
+	sb = page_address(rdev->sb_page);
+	sb->data_size = cpu_to_le64(num_sectors);
+	sb->super_offset = cpu_to_le64(rdev->sb_start);
+	sb->sb_csum = calc_sb_1_csum(sb);
+	do {
+		md_write_metadata(rdev->mddev, rdev, rdev->sb_start,
+				  rdev->sb_size, rdev->sb_page, 0);
+	} while (md_super_wait(rdev->mddev) < 0);
+	return num_sectors;
+
+}
+
+static int
+super_1_allow_new_offset(struct md_rdev *rdev,
+			 unsigned long long new_offset)
+{
+	struct mddev *mddev = rdev->mddev;
+
+	/* All necessary checks on new >= old have been done */
+	if (new_offset >= rdev->data_offset)
+		return 1;
+
+	/* with 1.0 metadata, there is no metadata to tread on
+	 * so we can always move back */
+	if (mddev->minor_version == 0)
+		return 1;
+
+	/* otherwise we must be sure not to step on
+	 * any metadata, so stay:
+	 * 36K beyond start of superblock
+	 * beyond end of badblocks
+	 * beyond write-intent bitmap
+	 */
+	if (rdev->sb_start + (32+4)*2 > new_offset)
+		return 0;
+
+	if (md_bitmap_registered(mddev) && !mddev->bitmap_info.file) {
+		struct md_bitmap_stats stats;
+		int err;
+
+		err = mddev->bitmap_ops->get_stats(mddev->bitmap, &stats);
+		if (!err && rdev->sb_start + mddev->bitmap_info.offset +
+		    stats.file_pages * (PAGE_SIZE >> 9) > new_offset)
+			return 0;
+	}
+
+	if (rdev->badblocks.sector + rdev->badblocks.size > new_offset)
+		return 0;
+
+	return 1;
+}
+
+static struct super_type super_types[] = {
+	[0] = {
+		.name	= "0.90.0",
+		.owner	= THIS_MODULE,
+		.load_super	    = super_90_load,
+		.validate_super	    = super_90_validate,
+		.sync_super	    = super_90_sync,
+		.rdev_size_change   = super_90_rdev_size_change,
+		.allow_new_offset   = super_90_allow_new_offset,
+	},
+	[1] = {
+		.name	= "md-1",
+		.owner	= THIS_MODULE,
+		.load_super	    = super_1_load,
+		.validate_super	    = super_1_validate,
+		.sync_super	    = super_1_sync,
+		.rdev_size_change   = super_1_rdev_size_change,
+		.allow_new_offset   = super_1_allow_new_offset,
+	},
+};
+
+static void sync_super(struct mddev *mddev, struct md_rdev *rdev)
+{
+	if (mddev->sync_super) {
+		mddev->sync_super(mddev, rdev);
+		return;
+	}
+
+	BUG_ON(mddev->major_version >= ARRAY_SIZE(super_types));
+
+	super_types[mddev->major_version].sync_super(mddev, rdev);
+}
+
+static int match_mddev_units(struct mddev *mddev1, struct mddev *mddev2)
+{
+	struct md_rdev *rdev, *rdev2;
+
+	rcu_read_lock();
+	rdev_for_each_rcu(rdev, mddev1) {
+		if (test_bit(Faulty, &rdev->flags) ||
+		    test_bit(Journal, &rdev->flags) ||
+		    rdev->raid_disk == -1)
+			continue;
+		rdev_for_each_rcu(rdev2, mddev2) {
+			if (test_bit(Faulty, &rdev2->flags) ||
+			    test_bit(Journal, &rdev2->flags) ||
+			    rdev2->raid_disk == -1)
+				continue;
+			if (rdev->bdev->bd_disk == rdev2->bdev->bd_disk) {
+				rcu_read_unlock();
+				return 1;
+			}
+		}
+	}
+	rcu_read_unlock();
+	return 0;
+}
+
+static LIST_HEAD(pending_raid_disks);
+
+/*
+ * Try to register data integrity profile for an mddev
+ *
+ * This is called when an array is started and after a disk has been kicked
+ * from the array. It only succeeds if all working and active component devices
+ * are integrity capable with matching profiles.
+ */
+int md_integrity_register(struct mddev *mddev)
+{
+	if (list_empty(&mddev->disks))
+		return 0; /* nothing to do */
+	if (mddev_is_dm(mddev) || !blk_get_integrity(mddev->gendisk))
+		return 0; /* shouldn't register */
+
+	pr_debug("md: data integrity enabled on %s\n", mdname(mddev));
+	return 0;
+}
+EXPORT_SYMBOL(md_integrity_register);
+
+static bool rdev_read_only(struct md_rdev *rdev)
+{
+	return bdev_read_only(rdev->bdev) ||
+		(rdev->meta_bdev && bdev_read_only(rdev->meta_bdev));
+}
+
+static int bind_rdev_to_array(struct md_rdev *rdev, struct mddev *mddev)
+{
+	char b[BDEVNAME_SIZE];
+	int err;
+
+	/* prevent duplicates */
+	if (find_rdev(mddev, rdev->bdev->bd_dev))
+		return -EEXIST;
+
+	if (rdev_read_only(rdev) && mddev->pers)
+		return -EROFS;
+
+	/* make sure rdev->sectors exceeds mddev->dev_sectors */
+	if (!test_bit(Journal, &rdev->flags) &&
+	    rdev->sectors &&
+	    (mddev->dev_sectors == 0 || rdev->sectors < mddev->dev_sectors)) {
+		if (mddev->pers) {
+			/* Cannot change size, so fail
+			 * If mddev->level <= 0, then we don't care
+			 * about aligning sizes (e.g. linear)
+			 */
+			if (mddev->level > 0)
+				return -ENOSPC;
+		} else
+			mddev->dev_sectors = rdev->sectors;
+	}
+
+	/* Verify rdev->desc_nr is unique.
+	 * If it is -1, assign a free number, else
+	 * check number is not in use
+	 */
+	rcu_read_lock();
+	if (rdev->desc_nr < 0) {
+		int choice = 0;
+		if (mddev->pers)
+			choice = mddev->raid_disks;
+		while (md_find_rdev_nr_rcu(mddev, choice))
+			choice++;
+		rdev->desc_nr = choice;
+	} else {
+		if (md_find_rdev_nr_rcu(mddev, rdev->desc_nr)) {
+			rcu_read_unlock();
+			return -EBUSY;
+		}
+	}
+	rcu_read_unlock();
+	if (!test_bit(Journal, &rdev->flags) &&
+	    mddev->max_disks && rdev->desc_nr >= mddev->max_disks) {
+		pr_warn("md: %s: array is limited to %d devices\n",
+			mdname(mddev), mddev->max_disks);
+		return -EBUSY;
+	}
+	snprintf(b, sizeof(b), "%pg", rdev->bdev);
+	strreplace(b, '/', '!');
+
+	rdev->mddev = mddev;
+	pr_debug("md: bind<%s>\n", b);
+
+	if (mddev->raid_disks)
+		mddev_create_serial_pool(mddev, rdev);
+
+	if ((err = kobject_add(&rdev->kobj, &mddev->kobj, "dev-%s", b)))
+		goto fail;
+
+	/* failure here is OK */
+	err = sysfs_create_link(&rdev->kobj, bdev_kobj(rdev->bdev), "block");
+	rdev->sysfs_state = sysfs_get_dirent_safe(rdev->kobj.sd, "state");
+	rdev->sysfs_unack_badblocks =
+		sysfs_get_dirent_safe(rdev->kobj.sd, "unacknowledged_bad_blocks");
+	rdev->sysfs_badblocks =
+		sysfs_get_dirent_safe(rdev->kobj.sd, "bad_blocks");
+
+	list_add_rcu(&rdev->same_set, &mddev->disks);
+	bd_link_disk_holder(rdev->bdev, mddev->gendisk);
+
+	return 0;
+
+ fail:
+	pr_warn("md: failed to register dev-%s for %s\n",
+		b, mdname(mddev));
+	mddev_destroy_serial_pool(mddev, rdev);
+	return err;
+}
+
+void md_autodetect_dev(dev_t dev);
+
+/* just for claiming the bdev */
+static struct md_rdev claim_rdev;
+
+static void export_rdev(struct md_rdev *rdev)
+{
+	pr_debug("md: export_rdev(%pg)\n", rdev->bdev);
+	md_rdev_clear(rdev);
+#ifndef MODULE
+	if (test_bit(AutoDetected, &rdev->flags))
+		md_autodetect_dev(rdev->bdev->bd_dev);
+#endif
+	fput(rdev->bdev_file);
+	rdev->bdev = NULL;
+	kobject_put(&rdev->kobj);
+}
+
+static void md_kick_rdev_from_array(struct md_rdev *rdev)
+{
+	struct mddev *mddev = rdev->mddev;
+
+	bd_unlink_disk_holder(rdev->bdev, rdev->mddev->gendisk);
+	list_del_rcu(&rdev->same_set);
+	pr_debug("md: unbind<%pg>\n", rdev->bdev);
+	mddev_destroy_serial_pool(rdev->mddev, rdev);
+	WRITE_ONCE(rdev->mddev, NULL);
+	sysfs_remove_link(&rdev->kobj, "block");
+	sysfs_put(rdev->sysfs_state);
+	sysfs_put(rdev->sysfs_unack_badblocks);
+	sysfs_put(rdev->sysfs_badblocks);
+	rdev->sysfs_state = NULL;
+	rdev->sysfs_unack_badblocks = NULL;
+	rdev->sysfs_badblocks = NULL;
+	rdev->badblocks.count = 0;
+
+	synchronize_rcu();
+
+	/*
+	 * kobject_del() will wait for all in progress writers to be done, where
+	 * reconfig_mutex is held, hence it can't be called under
+	 * reconfig_mutex and it's delayed to mddev_unlock().
+	 */
+	list_add(&rdev->same_set, &mddev->deleting);
+}
+
+static void export_array(struct mddev *mddev)
+{
+	struct md_rdev *rdev;
+
+	while (!list_empty(&mddev->disks)) {
+		rdev = list_first_entry(&mddev->disks, struct md_rdev,
+					same_set);
+		md_kick_rdev_from_array(rdev);
+	}
+	mddev->raid_disks = 0;
+	mddev->major_version = 0;
+}
+
+static bool set_in_sync(struct mddev *mddev)
+{
+	lockdep_assert_held(&mddev->lock);
+	if (!mddev->in_sync) {
+		mddev->sync_checkers++;
+		spin_unlock(&mddev->lock);
+		percpu_ref_switch_to_atomic_sync(&mddev->writes_pending);
+		spin_lock(&mddev->lock);
+		if (!mddev->in_sync &&
+		    percpu_ref_is_zero(&mddev->writes_pending)) {
+			mddev->in_sync = 1;
+			/*
+			 * Ensure ->in_sync is visible before we clear
+			 * ->sync_checkers.
+			 */
+			smp_mb();
+			set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
+			sysfs_notify_dirent_safe(mddev->sysfs_state);
+		}
+		if (--mddev->sync_checkers == 0)
+			percpu_ref_switch_to_percpu(&mddev->writes_pending);
+	}
+	if (mddev->safemode == 1)
+		mddev->safemode = 0;
+	return mddev->in_sync;
+}
+
+static void sync_sbs(struct mddev *mddev, int nospares)
+{
+	/* Update each superblock (in-memory image), but
+	 * if we are allowed to, skip spares which already
+	 * have the right event counter, or have one earlier
+	 * (which would mean they aren't being marked as dirty
+	 * with the rest of the array)
+	 */
+	struct md_rdev *rdev;
+	rdev_for_each(rdev, mddev) {
+		if (rdev->sb_events == mddev->events ||
+		    (nospares &&
+		     rdev->raid_disk < 0 &&
+		     rdev->sb_events+1 == mddev->events)) {
+			/* Don't update this superblock */
+			rdev->sb_loaded = 2;
+		} else {
+			sync_super(mddev, rdev);
+			rdev->sb_loaded = 1;
+		}
+	}
+}
+
+static bool does_sb_need_changing(struct mddev *mddev)
+{
+	struct md_rdev *rdev = NULL, *iter;
+	struct mdp_superblock_1 *sb;
+	int role;
+
+	/* Find a good rdev */
+	rdev_for_each(iter, mddev)
+		if ((iter->raid_disk >= 0) && !test_bit(Faulty, &iter->flags)) {
+			rdev = iter;
+			break;
+		}
+
+	/* No good device found. */
+	if (!rdev)
+		return false;
+
+	sb = page_address(rdev->sb_page);
+	/* Check if a device has become faulty or a spare become active */
+	rdev_for_each(rdev, mddev) {
+		role = le16_to_cpu(sb->dev_roles[rdev->desc_nr]);
+		/* Device activated? */
+		if (role == MD_DISK_ROLE_SPARE && rdev->raid_disk >= 0 &&
+		    !test_bit(Faulty, &rdev->flags))
+			return true;
+		/* Device turned faulty? */
+		if (test_bit(Faulty, &rdev->flags) && (role < MD_DISK_ROLE_MAX))
+			return true;
+	}
+
+	/* Check if any mddev parameters have changed */
+	if ((mddev->dev_sectors != le64_to_cpu(sb->size)) ||
+	    (mddev->reshape_position != le64_to_cpu(sb->reshape_position)) ||
+	    (mddev->layout != le32_to_cpu(sb->layout)) ||
+	    (mddev->raid_disks != le32_to_cpu(sb->raid_disks)) ||
+	    (mddev->chunk_sectors != le32_to_cpu(sb->chunksize)))
+		return true;
+
+	return false;
+}
+
+void md_update_sb(struct mddev *mddev, int force_change)
+{
+	struct md_rdev *rdev;
+	int sync_req;
+	int nospares = 0;
+	int any_badblocks_changed = 0;
+	int ret = -1;
+
+	if (!md_is_rdwr(mddev)) {
+		if (force_change)
+			set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
+		if (!mddev_is_dm(mddev))
+			pr_err_ratelimited("%s: can't update sb for read-only array %s\n",
+					   __func__, mdname(mddev));
+		return;
+	}
+
+repeat:
+	if (mddev_is_clustered(mddev)) {
+		if (test_and_clear_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags))
+			force_change = 1;
+		if (test_and_clear_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags))
+			nospares = 1;
+		ret = mddev->cluster_ops->metadata_update_start(mddev);
+		/* Has someone else has updated the sb */
+		if (!does_sb_need_changing(mddev)) {
+			if (ret == 0)
+				mddev->cluster_ops->metadata_update_cancel(mddev);
+			bit_clear_unless(&mddev->sb_flags, BIT(MD_SB_CHANGE_PENDING),
+							 BIT(MD_SB_CHANGE_DEVS) |
+							 BIT(MD_SB_CHANGE_CLEAN));
+			return;
+		}
+	}
+
+	/*
+	 * First make sure individual recovery_offsets are correct
+	 * curr_resync_completed can only be used during recovery.
+	 * During reshape/resync it might use array-addresses rather
+	 * that device addresses.
+	 */
+	rdev_for_each(rdev, mddev) {
+		if (rdev->raid_disk >= 0 &&
+		    mddev->delta_disks >= 0 &&
+		    test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) &&
+		    test_bit(MD_RECOVERY_RECOVER, &mddev->recovery) &&
+		    !test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
+		    !test_bit(Journal, &rdev->flags) &&
+		    !test_bit(In_sync, &rdev->flags) &&
+		    mddev->curr_resync_completed > rdev->recovery_offset)
+				rdev->recovery_offset = mddev->curr_resync_completed;
+
+	}
+	if (!mddev->persistent) {
+		clear_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
+		clear_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
+		if (!mddev->external) {
+			clear_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
+			rdev_for_each(rdev, mddev) {
+				if (rdev->badblocks.changed) {
+					rdev->badblocks.changed = 0;
+					ack_all_badblocks(&rdev->badblocks);
+					md_error(mddev, rdev);
+				}
+				clear_bit(Blocked, &rdev->flags);
+				clear_bit(BlockedBadBlocks, &rdev->flags);
+				wake_up(&rdev->blocked_wait);
+			}
+		}
+		wake_up(&mddev->sb_wait);
+		return;
+	}
+
+	spin_lock(&mddev->lock);
+
+	mddev->utime = ktime_get_real_seconds();
+
+	if (test_and_clear_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags))
+		force_change = 1;
+	if (test_and_clear_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags))
+		/* just a clean<-> dirty transition, possibly leave spares alone,
+		 * though if events isn't the right even/odd, we will have to do
+		 * spares after all
+		 */
+		nospares = 1;
+	if (force_change)
+		nospares = 0;
+	if (mddev->degraded)
+		/* If the array is degraded, then skipping spares is both
+		 * dangerous and fairly pointless.
+		 * Dangerous because a device that was removed from the array
+		 * might have a event_count that still looks up-to-date,
+		 * so it can be re-added without a resync.
+		 * Pointless because if there are any spares to skip,
+		 * then a recovery will happen and soon that array won't
+		 * be degraded any more and the spare can go back to sleep then.
+		 */
+		nospares = 0;
+
+	sync_req = mddev->in_sync;
+
+	/* If this is just a dirty<->clean transition, and the array is clean
+	 * and 'events' is odd, we can roll back to the previous clean state */
+	if (nospares
+	    && (mddev->in_sync && mddev->resync_offset == MaxSector)
+	    && mddev->can_decrease_events
+	    && mddev->events != 1) {
+		mddev->events--;
+		mddev->can_decrease_events = 0;
+	} else {
+		/* otherwise we have to go forward and ... */
+		mddev->events ++;
+		mddev->can_decrease_events = nospares;
+	}
+
+	/*
+	 * This 64-bit counter should never wrap.
+	 * Either we are in around ~1 trillion A.C., assuming
+	 * 1 reboot per second, or we have a bug...
+	 */
+	WARN_ON(mddev->events == 0);
+
+	rdev_for_each(rdev, mddev) {
+		if (rdev->badblocks.changed)
+			any_badblocks_changed++;
+		if (test_bit(Faulty, &rdev->flags))
+			set_bit(FaultRecorded, &rdev->flags);
+	}
+
+	sync_sbs(mddev, nospares);
+	spin_unlock(&mddev->lock);
+
+	pr_debug("md: updating %s RAID superblock on device (in sync %d)\n",
+		 mdname(mddev), mddev->in_sync);
+
+	mddev_add_trace_msg(mddev, "md md_update_sb");
+rewrite:
+	if (md_bitmap_enabled(mddev, false))
+		mddev->bitmap_ops->update_sb(mddev->bitmap);
+	rdev_for_each(rdev, mddev) {
+		if (rdev->sb_loaded != 1)
+			continue; /* no noise on spare devices */
+
+		if (!test_bit(Faulty, &rdev->flags)) {
+			md_write_metadata(mddev, rdev, rdev->sb_start,
+					  rdev->sb_size, rdev->sb_page, 0);
+			pr_debug("md: (write) %pg's sb offset: %llu\n",
+				 rdev->bdev,
+				 (unsigned long long)rdev->sb_start);
+			rdev->sb_events = mddev->events;
+			if (rdev->badblocks.size) {
+				md_write_metadata(mddev, rdev,
+						  rdev->badblocks.sector,
+						  rdev->badblocks.size << 9,
+						  rdev->bb_page, 0);
+				rdev->badblocks.size = 0;
+			}
+
+		} else
+			pr_debug("md: %pg (skipping faulty)\n",
+				 rdev->bdev);
+	}
+	if (md_super_wait(mddev) < 0)
+		goto rewrite;
+	/* if there was a failure, MD_SB_CHANGE_DEVS was set, and we re-write super */
+
+	if (mddev_is_clustered(mddev) && ret == 0)
+		mddev->cluster_ops->metadata_update_finish(mddev);
+
+	if (mddev->in_sync != sync_req ||
+	    !bit_clear_unless(&mddev->sb_flags, BIT(MD_SB_CHANGE_PENDING),
+			       BIT(MD_SB_CHANGE_DEVS) | BIT(MD_SB_CHANGE_CLEAN)))
+		/* have to write it out again */
+		goto repeat;
+	wake_up(&mddev->sb_wait);
+	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+		sysfs_notify_dirent_safe(mddev->sysfs_completed);
+
+	rdev_for_each(rdev, mddev) {
+		if (test_and_clear_bit(FaultRecorded, &rdev->flags))
+			clear_bit(Blocked, &rdev->flags);
+
+		if (any_badblocks_changed)
+			ack_all_badblocks(&rdev->badblocks);
+		clear_bit(BlockedBadBlocks, &rdev->flags);
+		wake_up(&rdev->blocked_wait);
+	}
+}
+EXPORT_SYMBOL(md_update_sb);
+
+static int add_bound_rdev(struct md_rdev *rdev)
+{
+	struct mddev *mddev = rdev->mddev;
+	int err = 0;
+	bool add_journal = test_bit(Journal, &rdev->flags);
+
+	if (!mddev->pers->hot_remove_disk || add_journal) {
+		/* If there is hot_add_disk but no hot_remove_disk
+		 * then added disks for geometry changes,
+		 * and should be added immediately.
+		 */
+		super_types[mddev->major_version].
+			validate_super(mddev, NULL/*freshest*/, rdev);
+		err = mddev->pers->hot_add_disk(mddev, rdev);
+		if (err) {
+			md_kick_rdev_from_array(rdev);
+			return err;
+		}
+	}
+	sysfs_notify_dirent_safe(rdev->sysfs_state);
+
+	set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
+	if (mddev->degraded)
+		set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
+	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	md_new_event();
+	return 0;
+}
+
+/* words written to sysfs files may, or may not, be \n terminated.
+ * We want to accept with case. For this we use cmd_match.
+ */
+static int cmd_match(const char *cmd, const char *str)
+{
+	/* See if cmd, written into a sysfs file, matches
+	 * str.  They must either be the same, or cmd can
+	 * have a trailing newline
+	 */
+	while (*cmd && *str && *cmd == *str) {
+		cmd++;
+		str++;
+	}
+	if (*cmd == '\n')
+		cmd++;
+	if (*str || *cmd)
+		return 0;
+	return 1;
+}
+
+struct rdev_sysfs_entry {
+	struct attribute attr;
+	ssize_t (*show)(struct md_rdev *, char *);
+	ssize_t (*store)(struct md_rdev *, const char *, size_t);
+};
+
+static ssize_t
+state_show(struct md_rdev *rdev, char *page)
+{
+	char *sep = ",";
+	size_t len = 0;
+	unsigned long flags = READ_ONCE(rdev->flags);
+
+	if (test_bit(Faulty, &flags) ||
+	    (!test_bit(ExternalBbl, &flags) &&
+	    rdev->badblocks.unacked_exist))
+		len += sprintf(page+len, "faulty%s", sep);
+	if (test_bit(In_sync, &flags))
+		len += sprintf(page+len, "in_sync%s", sep);
+	if (test_bit(Journal, &flags))
+		len += sprintf(page+len, "journal%s", sep);
+	if (test_bit(WriteMostly, &flags))
+		len += sprintf(page+len, "write_mostly%s", sep);
+	if (test_bit(Blocked, &flags) ||
+	    (rdev->badblocks.unacked_exist
+	     && !test_bit(Faulty, &flags)))
+		len += sprintf(page+len, "blocked%s", sep);
+	if (!test_bit(Faulty, &flags) &&
+	    !test_bit(Journal, &flags) &&
+	    !test_bit(In_sync, &flags))
+		len += sprintf(page+len, "spare%s", sep);
+	if (test_bit(WriteErrorSeen, &flags))
+		len += sprintf(page+len, "write_error%s", sep);
+	if (test_bit(WantReplacement, &flags))
+		len += sprintf(page+len, "want_replacement%s", sep);
+	if (test_bit(Replacement, &flags))
+		len += sprintf(page+len, "replacement%s", sep);
+	if (test_bit(ExternalBbl, &flags))
+		len += sprintf(page+len, "external_bbl%s", sep);
+	if (test_bit(FailFast, &flags))
+		len += sprintf(page+len, "failfast%s", sep);
+
+	if (len)
+		len -= strlen(sep);
+
+	return len+sprintf(page+len, "\n");
+}
+
+static ssize_t
+state_store(struct md_rdev *rdev, const char *buf, size_t len)
+{
+	/* can write
+	 *  faulty  - simulates an error
+	 *  remove  - disconnects the device
+	 *  writemostly - sets write_mostly
+	 *  -writemostly - clears write_mostly
+	 *  blocked - sets the Blocked flags
+	 *  -blocked - clears the Blocked and possibly simulates an error
+	 *  insync - sets Insync providing device isn't active
+	 *  -insync - clear Insync for a device with a slot assigned,
+	 *            so that it gets rebuilt based on bitmap
+	 *  write_error - sets WriteErrorSeen
+	 *  -write_error - clears WriteErrorSeen
+	 *  {,-}failfast - set/clear FailFast
+	 */
+
+	struct mddev *mddev = rdev->mddev;
+	int err = -EINVAL;
+	bool need_update_sb = false;
+
+	if (cmd_match(buf, "faulty") && rdev->mddev->pers) {
+		md_error(rdev->mddev, rdev);
+
+		if (test_bit(MD_BROKEN, &rdev->mddev->flags))
+			err = -EBUSY;
+		else
+			err = 0;
+	} else if (cmd_match(buf, "remove")) {
+		if (rdev->mddev->pers) {
+			clear_bit(Blocked, &rdev->flags);
+			remove_and_add_spares(rdev->mddev, rdev);
+		}
+		if (rdev->raid_disk >= 0)
+			err = -EBUSY;
+		else {
+			err = 0;
+			if (mddev_is_clustered(mddev))
+				err = mddev->cluster_ops->remove_disk(mddev, rdev);
+
+			if (err == 0) {
+				md_kick_rdev_from_array(rdev);
+				if (mddev->pers)
+					set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
+				md_new_event();
+			}
+		}
+	} else if (cmd_match(buf, "writemostly")) {
+		set_bit(WriteMostly, &rdev->flags);
+		mddev_create_serial_pool(rdev->mddev, rdev);
+		need_update_sb = true;
+		err = 0;
+	} else if (cmd_match(buf, "-writemostly")) {
+		mddev_destroy_serial_pool(rdev->mddev, rdev);
+		clear_bit(WriteMostly, &rdev->flags);
+		need_update_sb = true;
+		err = 0;
+	} else if (cmd_match(buf, "blocked")) {
+		set_bit(Blocked, &rdev->flags);
+		err = 0;
+	} else if (cmd_match(buf, "-blocked")) {
+		if (!test_bit(Faulty, &rdev->flags) &&
+		    !test_bit(ExternalBbl, &rdev->flags) &&
+		    rdev->badblocks.unacked_exist) {
+			/* metadata handler doesn't understand badblocks,
+			 * so we need to fail the device
+			 */
+			md_error(rdev->mddev, rdev);
+		}
+		clear_bit(Blocked, &rdev->flags);
+		clear_bit(BlockedBadBlocks, &rdev->flags);
+		wake_up(&rdev->blocked_wait);
+		set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
+
+		err = 0;
+	} else if (cmd_match(buf, "insync") && rdev->raid_disk == -1) {
+		set_bit(In_sync, &rdev->flags);
+		err = 0;
+	} else if (cmd_match(buf, "failfast")) {
+		set_bit(FailFast, &rdev->flags);
+		need_update_sb = true;
+		err = 0;
+	} else if (cmd_match(buf, "-failfast")) {
+		clear_bit(FailFast, &rdev->flags);
+		need_update_sb = true;
+		err = 0;
+	} else if (cmd_match(buf, "-insync") && rdev->raid_disk >= 0 &&
+		   !test_bit(Journal, &rdev->flags)) {
+		if (rdev->mddev->pers == NULL) {
+			clear_bit(In_sync, &rdev->flags);
+			rdev->saved_raid_disk = rdev->raid_disk;
+			rdev->raid_disk = -1;
+			err = 0;
+		}
+	} else if (cmd_match(buf, "write_error")) {
+		set_bit(WriteErrorSeen, &rdev->flags);
+		err = 0;
+	} else if (cmd_match(buf, "-write_error")) {
+		clear_bit(WriteErrorSeen, &rdev->flags);
+		err = 0;
+	} else if (cmd_match(buf, "want_replacement")) {
+		/* Any non-spare device that is not a replacement can
+		 * become want_replacement at any time, but we then need to
+		 * check if recovery is needed.
+		 */
+		if (rdev->raid_disk >= 0 &&
+		    !test_bit(Journal, &rdev->flags) &&
+		    !test_bit(Replacement, &rdev->flags))
+			set_bit(WantReplacement, &rdev->flags);
+		set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
+		err = 0;
+	} else if (cmd_match(buf, "-want_replacement")) {
+		/* Clearing 'want_replacement' is always allowed.
+		 * Once replacements starts it is too late though.
+		 */
+		err = 0;
+		clear_bit(WantReplacement, &rdev->flags);
+	} else if (cmd_match(buf, "replacement")) {
+		/* Can only set a device as a replacement when array has not
+		 * yet been started.  Once running, replacement is automatic
+		 * from spares, or by assigning 'slot'.
+		 */
+		if (rdev->mddev->pers)
+			err = -EBUSY;
+		else {
+			set_bit(Replacement, &rdev->flags);
+			err = 0;
+		}
+	} else if (cmd_match(buf, "-replacement")) {
+		/* Similarly, can only clear Replacement before start */
+		if (rdev->mddev->pers)
+			err = -EBUSY;
+		else {
+			clear_bit(Replacement, &rdev->flags);
+			err = 0;
+		}
+	} else if (cmd_match(buf, "re-add")) {
+		if (!rdev->mddev->pers)
+			err = -EINVAL;
+		else if (test_bit(Faulty, &rdev->flags) && (rdev->raid_disk == -1) &&
+				rdev->saved_raid_disk >= 0) {
+			/* clear_bit is performed _after_ all the devices
+			 * have their local Faulty bit cleared. If any writes
+			 * happen in the meantime in the local node, they
+			 * will land in the local bitmap, which will be synced
+			 * by this node eventually
+			 */
+			if (!mddev_is_clustered(rdev->mddev) ||
+			    (err = mddev->cluster_ops->gather_bitmaps(rdev)) == 0) {
+				clear_bit(Faulty, &rdev->flags);
+				err = add_bound_rdev(rdev);
+			}
+		} else
+			err = -EBUSY;
+	} else if (cmd_match(buf, "external_bbl") && (rdev->mddev->external)) {
+		set_bit(ExternalBbl, &rdev->flags);
+		rdev->badblocks.shift = 0;
+		err = 0;
+	} else if (cmd_match(buf, "-external_bbl") && (rdev->mddev->external)) {
+		clear_bit(ExternalBbl, &rdev->flags);
+		err = 0;
+	}
+	if (need_update_sb)
+		md_update_sb(mddev, 1);
+	if (!err)
+		sysfs_notify_dirent_safe(rdev->sysfs_state);
+	return err ? err : len;
+}
+static struct rdev_sysfs_entry rdev_state =
+__ATTR_PREALLOC(state, S_IRUGO|S_IWUSR, state_show, state_store);
+
+static ssize_t
+errors_show(struct md_rdev *rdev, char *page)
+{
+	return sprintf(page, "%d\n", atomic_read(&rdev->corrected_errors));
+}
+
+static ssize_t
+errors_store(struct md_rdev *rdev, const char *buf, size_t len)
+{
+	unsigned int n;
+	int rv;
+
+	rv = kstrtouint(buf, 10, &n);
+	if (rv < 0)
+		return rv;
+	atomic_set(&rdev->corrected_errors, n);
+	return len;
+}
+static struct rdev_sysfs_entry rdev_errors =
+__ATTR(errors, S_IRUGO|S_IWUSR, errors_show, errors_store);
+
+static ssize_t
+slot_show(struct md_rdev *rdev, char *page)
+{
+	if (test_bit(Journal, &rdev->flags))
+		return sprintf(page, "journal\n");
+	else if (rdev->raid_disk < 0)
+		return sprintf(page, "none\n");
+	else
+		return sprintf(page, "%d\n", rdev->raid_disk);
+}
+
+static ssize_t
+slot_store(struct md_rdev *rdev, const char *buf, size_t len)
+{
+	int slot;
+	int err;
+
+	if (test_bit(Journal, &rdev->flags))
+		return -EBUSY;
+	if (strncmp(buf, "none", 4)==0)
+		slot = -1;
+	else {
+		err = kstrtouint(buf, 10, (unsigned int *)&slot);
+		if (err < 0)
+			return err;
+		if (slot < 0)
+			/* overflow */
+			return -ENOSPC;
+	}
+	if (rdev->mddev->pers && slot == -1) {
+		/* Setting 'slot' on an active array requires also
+		 * updating the 'rd%d' link, and communicating
+		 * with the personality with ->hot_*_disk.
+		 * For now we only support removing
+		 * failed/spare devices.  This normally happens automatically,
+		 * but not when the metadata is externally managed.
+		 */
+		if (rdev->raid_disk == -1)
+			return -EEXIST;
+		/* personality does all needed checks */
+		if (rdev->mddev->pers->hot_remove_disk == NULL)
+			return -EINVAL;
+		clear_bit(Blocked, &rdev->flags);
+		remove_and_add_spares(rdev->mddev, rdev);
+		if (rdev->raid_disk >= 0)
+			return -EBUSY;
+		set_bit(MD_RECOVERY_NEEDED, &rdev->mddev->recovery);
+	} else if (rdev->mddev->pers) {
+		/* Activating a spare .. or possibly reactivating
+		 * if we ever get bitmaps working here.
+		 */
+		int err;
+
+		if (rdev->raid_disk != -1)
+			return -EBUSY;
+
+		if (test_bit(MD_RECOVERY_RUNNING, &rdev->mddev->recovery))
+			return -EBUSY;
+
+		if (rdev->mddev->pers->hot_add_disk == NULL)
+			return -EINVAL;
+
+		if (slot >= rdev->mddev->raid_disks &&
+		    slot >= rdev->mddev->raid_disks + rdev->mddev->delta_disks)
+			return -ENOSPC;
+
+		rdev->raid_disk = slot;
+		if (test_bit(In_sync, &rdev->flags))
+			rdev->saved_raid_disk = slot;
+		else
+			rdev->saved_raid_disk = -1;
+		clear_bit(In_sync, &rdev->flags);
+		clear_bit(Bitmap_sync, &rdev->flags);
+		err = rdev->mddev->pers->hot_add_disk(rdev->mddev, rdev);
+		if (err) {
+			rdev->raid_disk = -1;
+			return err;
+		} else
+			sysfs_notify_dirent_safe(rdev->sysfs_state);
+		/* failure here is OK */;
+		sysfs_link_rdev(rdev->mddev, rdev);
+		/* don't wakeup anyone, leave that to userspace. */
+	} else {
+		if (slot >= rdev->mddev->raid_disks &&
+		    slot >= rdev->mddev->raid_disks + rdev->mddev->delta_disks)
+			return -ENOSPC;
+		rdev->raid_disk = slot;
+		/* assume it is working */
+		clear_bit(Faulty, &rdev->flags);
+		clear_bit(WriteMostly, &rdev->flags);
+		set_bit(In_sync, &rdev->flags);
+		sysfs_notify_dirent_safe(rdev->sysfs_state);
+	}
+	return len;
+}
+
+static struct rdev_sysfs_entry rdev_slot =
+__ATTR(slot, S_IRUGO|S_IWUSR, slot_show, slot_store);
+
+static ssize_t
+offset_show(struct md_rdev *rdev, char *page)
+{
+	return sprintf(page, "%llu\n", (unsigned long long)rdev->data_offset);
+}
+
+static ssize_t
+offset_store(struct md_rdev *rdev, const char *buf, size_t len)
+{
+	unsigned long long offset;
+	if (kstrtoull(buf, 10, &offset) < 0)
+		return -EINVAL;
+	if (rdev->mddev->pers && rdev->raid_disk >= 0)
+		return -EBUSY;
+	if (rdev->sectors && rdev->mddev->external)
+		/* Must set offset before size, so overlap checks
+		 * can be sane */
+		return -EBUSY;
+	rdev->data_offset = offset;
+	rdev->new_data_offset = offset;
+	return len;
+}
+
+static struct rdev_sysfs_entry rdev_offset =
+__ATTR(offset, S_IRUGO|S_IWUSR, offset_show, offset_store);
+
+static ssize_t new_offset_show(struct md_rdev *rdev, char *page)
+{
+	return sprintf(page, "%llu\n",
+		       (unsigned long long)rdev->new_data_offset);
+}
+
+static ssize_t new_offset_store(struct md_rdev *rdev,
+				const char *buf, size_t len)
+{
+	unsigned long long new_offset;
+	struct mddev *mddev = rdev->mddev;
+
+	if (kstrtoull(buf, 10, &new_offset) < 0)
+		return -EINVAL;
+
+	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+		return -EBUSY;
+	if (new_offset == rdev->data_offset)
+		/* reset is always permitted */
+		;
+	else if (new_offset > rdev->data_offset) {
+		/* must not push array size beyond rdev_sectors */
+		if (new_offset - rdev->data_offset
+		    + mddev->dev_sectors > rdev->sectors)
+				return -E2BIG;
+	}
+	/* Metadata worries about other space details. */
+
+	/* decreasing the offset is inconsistent with a backwards
+	 * reshape.
+	 */
+	if (new_offset < rdev->data_offset &&
+	    mddev->reshape_backwards)
+		return -EINVAL;
+	/* Increasing offset is inconsistent with forwards
+	 * reshape.  reshape_direction should be set to
+	 * 'backwards' first.
+	 */
+	if (new_offset > rdev->data_offset &&
+	    !mddev->reshape_backwards)
+		return -EINVAL;
+
+	if (mddev->pers && mddev->persistent &&
+	    !super_types[mddev->major_version]
+	    .allow_new_offset(rdev, new_offset))
+		return -E2BIG;
+	rdev->new_data_offset = new_offset;
+	if (new_offset > rdev->data_offset)
+		mddev->reshape_backwards = 1;
+	else if (new_offset < rdev->data_offset)
+		mddev->reshape_backwards = 0;
+
+	return len;
+}
+static struct rdev_sysfs_entry rdev_new_offset =
+__ATTR(new_offset, S_IRUGO|S_IWUSR, new_offset_show, new_offset_store);
+
+static ssize_t
+rdev_size_show(struct md_rdev *rdev, char *page)
+{
+	return sprintf(page, "%llu\n", (unsigned long long)rdev->sectors / 2);
+}
+
+static int md_rdevs_overlap(struct md_rdev *a, struct md_rdev *b)
+{
+	/* check if two start/length pairs overlap */
+	if (a->data_offset + a->sectors <= b->data_offset)
+		return false;
+	if (b->data_offset + b->sectors <= a->data_offset)
+		return false;
+	return true;
+}
+
+static bool md_rdev_overlaps(struct md_rdev *rdev)
+{
+	struct mddev *mddev;
+	struct md_rdev *rdev2;
+
+	spin_lock(&all_mddevs_lock);
+	list_for_each_entry(mddev, &all_mddevs, all_mddevs) {
+		if (test_bit(MD_DELETED, &mddev->flags))
+			continue;
+		rdev_for_each(rdev2, mddev) {
+			if (rdev != rdev2 && rdev->bdev == rdev2->bdev &&
+			    md_rdevs_overlap(rdev, rdev2)) {
+				spin_unlock(&all_mddevs_lock);
+				return true;
+			}
+		}
+	}
+	spin_unlock(&all_mddevs_lock);
+	return false;
+}
+
+static int strict_blocks_to_sectors(const char *buf, sector_t *sectors)
+{
+	unsigned long long blocks;
+	sector_t new;
+
+	if (kstrtoull(buf, 10, &blocks) < 0)
+		return -EINVAL;
+
+	if (blocks & 1ULL << (8 * sizeof(blocks) - 1))
+		return -EINVAL; /* sector conversion overflow */
+
+	new = blocks * 2;
+	if (new != blocks * 2)
+		return -EINVAL; /* unsigned long long to sector_t overflow */
+
+	*sectors = new;
+	return 0;
+}
+
+static ssize_t
+rdev_size_store(struct md_rdev *rdev, const char *buf, size_t len)
+{
+	struct mddev *my_mddev = rdev->mddev;
+	sector_t oldsectors = rdev->sectors;
+	sector_t sectors;
+
+	if (test_bit(Journal, &rdev->flags))
+		return -EBUSY;
+	if (strict_blocks_to_sectors(buf, &sectors) < 0)
+		return -EINVAL;
+	if (rdev->data_offset != rdev->new_data_offset)
+		return -EINVAL; /* too confusing */
+	if (my_mddev->pers && rdev->raid_disk >= 0) {
+		if (my_mddev->persistent) {
+			sectors = super_types[my_mddev->major_version].
+				rdev_size_change(rdev, sectors);
+			if (!sectors)
+				return -EBUSY;
+		} else if (!sectors)
+			sectors = bdev_nr_sectors(rdev->bdev) -
+				rdev->data_offset;
+		if (!my_mddev->pers->resize)
+			/* Cannot change size for RAID0 or Linear etc */
+			return -EINVAL;
+	}
+	if (sectors < my_mddev->dev_sectors)
+		return -EINVAL; /* component must fit device */
+
+	rdev->sectors = sectors;
+
+	/*
+	 * Check that all other rdevs with the same bdev do not overlap.  This
+	 * check does not provide a hard guarantee, it just helps avoid
+	 * dangerous mistakes.
+	 */
+	if (sectors > oldsectors && my_mddev->external &&
+	    md_rdev_overlaps(rdev)) {
+		/*
+		 * Someone else could have slipped in a size change here, but
+		 * doing so is just silly.  We put oldsectors back because we
+		 * know it is safe, and trust userspace not to race with itself.
+		 */
+		rdev->sectors = oldsectors;
+		return -EBUSY;
+	}
+	return len;
+}
+
+static struct rdev_sysfs_entry rdev_size =
+__ATTR(size, S_IRUGO|S_IWUSR, rdev_size_show, rdev_size_store);
+
+static ssize_t recovery_start_show(struct md_rdev *rdev, char *page)
+{
+	unsigned long long recovery_start = rdev->recovery_offset;
+
+	if (test_bit(In_sync, &rdev->flags) ||
+	    recovery_start == MaxSector)
+		return sprintf(page, "none\n");
+
+	return sprintf(page, "%llu\n", recovery_start);
+}
+
+static ssize_t recovery_start_store(struct md_rdev *rdev, const char *buf, size_t len)
+{
+	unsigned long long recovery_start;
+
+	if (cmd_match(buf, "none"))
+		recovery_start = MaxSector;
+	else if (kstrtoull(buf, 10, &recovery_start))
+		return -EINVAL;
+
+	if (rdev->mddev->pers &&
+	    rdev->raid_disk >= 0)
+		return -EBUSY;
+
+	rdev->recovery_offset = recovery_start;
+	if (recovery_start == MaxSector)
+		set_bit(In_sync, &rdev->flags);
+	else
+		clear_bit(In_sync, &rdev->flags);
+	return len;
+}
+
+static struct rdev_sysfs_entry rdev_recovery_start =
+__ATTR(recovery_start, S_IRUGO|S_IWUSR, recovery_start_show, recovery_start_store);
+
+/* sysfs access to bad-blocks list.
+ * We present two files.
+ * 'bad-blocks' lists sector numbers and lengths of ranges that
+ *    are recorded as bad.  The list is truncated to fit within
+ *    the one-page limit of sysfs.
+ *    Writing "sector length" to this file adds an acknowledged
+ *    bad block list.
+ * 'unacknowledged-bad-blocks' lists bad blocks that have not yet
+ *    been acknowledged.  Writing to this file adds bad blocks
+ *    without acknowledging them.  This is largely for testing.
+ */
+static ssize_t bb_show(struct md_rdev *rdev, char *page)
+{
+	return badblocks_show(&rdev->badblocks, page, 0);
+}
+static ssize_t bb_store(struct md_rdev *rdev, const char *page, size_t len)
+{
+	int rv = badblocks_store(&rdev->badblocks, page, len, 0);
+	/* Maybe that ack was all we needed */
+	if (test_and_clear_bit(BlockedBadBlocks, &rdev->flags))
+		wake_up(&rdev->blocked_wait);
+	return rv;
+}
+static struct rdev_sysfs_entry rdev_bad_blocks =
+__ATTR(bad_blocks, S_IRUGO|S_IWUSR, bb_show, bb_store);
+
+static ssize_t ubb_show(struct md_rdev *rdev, char *page)
+{
+	return badblocks_show(&rdev->badblocks, page, 1);
+}
+static ssize_t ubb_store(struct md_rdev *rdev, const char *page, size_t len)
+{
+	return badblocks_store(&rdev->badblocks, page, len, 1);
+}
+static struct rdev_sysfs_entry rdev_unack_bad_blocks =
+__ATTR(unacknowledged_bad_blocks, S_IRUGO|S_IWUSR, ubb_show, ubb_store);
+
+static ssize_t
+ppl_sector_show(struct md_rdev *rdev, char *page)
+{
+	return sprintf(page, "%llu\n", (unsigned long long)rdev->ppl.sector);
+}
+
+static ssize_t
+ppl_sector_store(struct md_rdev *rdev, const char *buf, size_t len)
+{
+	unsigned long long sector;
+
+	if (kstrtoull(buf, 10, &sector) < 0)
+		return -EINVAL;
+	if (sector != (sector_t)sector)
+		return -EINVAL;
+
+	if (rdev->mddev->pers && test_bit(MD_HAS_PPL, &rdev->mddev->flags) &&
+	    rdev->raid_disk >= 0)
+		return -EBUSY;
+
+	if (rdev->mddev->persistent) {
+		if (rdev->mddev->major_version == 0)
+			return -EINVAL;
+		if ((sector > rdev->sb_start &&
+		     sector - rdev->sb_start > S16_MAX) ||
+		    (sector < rdev->sb_start &&
+		     rdev->sb_start - sector > -S16_MIN))
+			return -EINVAL;
+		rdev->ppl.offset = sector - rdev->sb_start;
+	} else if (!rdev->mddev->external) {
+		return -EBUSY;
+	}
+	rdev->ppl.sector = sector;
+	return len;
+}
+
+static struct rdev_sysfs_entry rdev_ppl_sector =
+__ATTR(ppl_sector, S_IRUGO|S_IWUSR, ppl_sector_show, ppl_sector_store);
+
+static ssize_t
+ppl_size_show(struct md_rdev *rdev, char *page)
+{
+	return sprintf(page, "%u\n", rdev->ppl.size);
+}
+
+static ssize_t
+ppl_size_store(struct md_rdev *rdev, const char *buf, size_t len)
+{
+	unsigned int size;
+
+	if (kstrtouint(buf, 10, &size) < 0)
+		return -EINVAL;
+
+	if (rdev->mddev->pers && test_bit(MD_HAS_PPL, &rdev->mddev->flags) &&
+	    rdev->raid_disk >= 0)
+		return -EBUSY;
+
+	if (rdev->mddev->persistent) {
+		if (rdev->mddev->major_version == 0)
+			return -EINVAL;
+		if (size > U16_MAX)
+			return -EINVAL;
+	} else if (!rdev->mddev->external) {
+		return -EBUSY;
+	}
+	rdev->ppl.size = size;
+	return len;
+}
+
+static struct rdev_sysfs_entry rdev_ppl_size =
+__ATTR(ppl_size, S_IRUGO|S_IWUSR, ppl_size_show, ppl_size_store);
+
+static struct attribute *rdev_default_attrs[] = {
+	&rdev_state.attr,
+	&rdev_errors.attr,
+	&rdev_slot.attr,
+	&rdev_offset.attr,
+	&rdev_new_offset.attr,
+	&rdev_size.attr,
+	&rdev_recovery_start.attr,
+	&rdev_bad_blocks.attr,
+	&rdev_unack_bad_blocks.attr,
+	&rdev_ppl_sector.attr,
+	&rdev_ppl_size.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(rdev_default);
+static ssize_t
+rdev_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
+{
+	struct rdev_sysfs_entry *entry = container_of(attr, struct rdev_sysfs_entry, attr);
+	struct md_rdev *rdev = container_of(kobj, struct md_rdev, kobj);
+
+	if (!entry->show)
+		return -EIO;
+	if (!rdev->mddev)
+		return -ENODEV;
+	return entry->show(rdev, page);
+}
+
+static ssize_t
+rdev_attr_store(struct kobject *kobj, struct attribute *attr,
+	      const char *page, size_t length)
+{
+	struct rdev_sysfs_entry *entry = container_of(attr, struct rdev_sysfs_entry, attr);
+	struct md_rdev *rdev = container_of(kobj, struct md_rdev, kobj);
+	struct kernfs_node *kn = NULL;
+	bool suspend = false;
+	ssize_t rv;
+	struct mddev *mddev = READ_ONCE(rdev->mddev);
+
+	if (!entry->store)
+		return -EIO;
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+	if (!mddev)
+		return -ENODEV;
+
+	if (entry->store == state_store) {
+		if (cmd_match(page, "remove"))
+			kn = sysfs_break_active_protection(kobj, attr);
+		if (cmd_match(page, "remove") || cmd_match(page, "re-add") ||
+		    cmd_match(page, "writemostly") ||
+		    cmd_match(page, "-writemostly"))
+			suspend = true;
+	}
+
+	rv = suspend ? mddev_suspend_and_lock(mddev) : mddev_lock(mddev);
+	if (!rv) {
+		if (rdev->mddev == NULL)
+			rv = -ENODEV;
+		else
+			rv = entry->store(rdev, page, length);
+		suspend ? mddev_unlock_and_resume(mddev) : mddev_unlock(mddev);
+	}
+
+	if (kn)
+		sysfs_unbreak_active_protection(kn);
+
+	return rv;
+}
+
+static void rdev_free(struct kobject *ko)
+{
+	struct md_rdev *rdev = container_of(ko, struct md_rdev, kobj);
+	kfree(rdev);
+}
+static const struct sysfs_ops rdev_sysfs_ops = {
+	.show		= rdev_attr_show,
+	.store		= rdev_attr_store,
+};
+static const struct kobj_type rdev_ktype = {
+	.release	= rdev_free,
+	.sysfs_ops	= &rdev_sysfs_ops,
+	.default_groups	= rdev_default_groups,
+};
+
+int md_rdev_init(struct md_rdev *rdev)
+{
+	rdev->desc_nr = -1;
+	rdev->saved_raid_disk = -1;
+	rdev->raid_disk = -1;
+	rdev->flags = 0;
+	rdev->data_offset = 0;
+	rdev->new_data_offset = 0;
+	rdev->sb_events = 0;
+	rdev->last_read_error = 0;
+	rdev->sb_loaded = 0;
+	rdev->bb_page = NULL;
+	atomic_set(&rdev->nr_pending, 0);
+	atomic_set(&rdev->read_errors, 0);
+	atomic_set(&rdev->corrected_errors, 0);
+
+	INIT_LIST_HEAD(&rdev->same_set);
+	init_waitqueue_head(&rdev->blocked_wait);
+
+	/* Add space to store bad block list.
+	 * This reserves the space even on arrays where it cannot
+	 * be used - I wonder if that matters
+	 */
+	return badblocks_init(&rdev->badblocks, 0);
+}
+EXPORT_SYMBOL_GPL(md_rdev_init);
+
+/*
+ * Import a device. If 'super_format' >= 0, then sanity check the superblock
+ *
+ * mark the device faulty if:
+ *
+ *   - the device is nonexistent (zero size)
+ *   - the device has no valid superblock
+ *
+ * a faulty rdev _never_ has rdev->sb set.
+ */
+static struct md_rdev *md_import_device(dev_t newdev, int super_format, int super_minor)
+{
+	struct md_rdev *rdev;
+	sector_t size;
+	int err;
+
+	rdev = kzalloc_obj(*rdev);
+	if (!rdev)
+		return ERR_PTR(-ENOMEM);
+
+	err = md_rdev_init(rdev);
+	if (err)
+		goto out_free_rdev;
+	err = alloc_disk_sb(rdev);
+	if (err)
+		goto out_clear_rdev;
+
+	rdev->bdev_file = bdev_file_open_by_dev(newdev,
+			BLK_OPEN_READ | BLK_OPEN_WRITE,
+			super_format == -2 ? &claim_rdev : rdev, NULL);
+	if (IS_ERR(rdev->bdev_file)) {
+		pr_warn("md: could not open device unknown-block(%u,%u).\n",
+			MAJOR(newdev), MINOR(newdev));
+		err = PTR_ERR(rdev->bdev_file);
+		goto out_clear_rdev;
+	}
+	rdev->bdev = file_bdev(rdev->bdev_file);
+
+	kobject_init(&rdev->kobj, &rdev_ktype);
+
+	size = bdev_nr_bytes(rdev->bdev) >> BLOCK_SIZE_BITS;
+	if (!size) {
+		pr_warn("md: %pg has zero or unknown size, marking faulty!\n",
+			rdev->bdev);
+		err = -EINVAL;
+		goto out_blkdev_put;
+	}
+
+	if (super_format >= 0) {
+		err = super_types[super_format].
+			load_super(rdev, NULL, super_minor);
+		if (err == -EINVAL) {
+			pr_warn("md: %pg does not have a valid v%d.%d superblock, not importing!\n",
+				rdev->bdev,
+				super_format, super_minor);
+			goto out_blkdev_put;
+		}
+		if (err < 0) {
+			pr_warn("md: could not read %pg's sb, not importing!\n",
+				rdev->bdev);
+			goto out_blkdev_put;
+		}
+	}
+
+	return rdev;
+
+out_blkdev_put:
+	fput(rdev->bdev_file);
+out_clear_rdev:
+	md_rdev_clear(rdev);
+out_free_rdev:
+	kfree(rdev);
+	return ERR_PTR(err);
+}
+
+/*
+ * Check a full RAID array for plausibility
+ */
+
+static int analyze_sbs(struct mddev *mddev)
+{
+	struct md_rdev *rdev, *freshest, *tmp;
+
+	freshest = NULL;
+	rdev_for_each_safe(rdev, tmp, mddev)
+		switch (super_types[mddev->major_version].
+			load_super(rdev, freshest, mddev->minor_version)) {
+		case 1:
+			freshest = rdev;
+			break;
+		case 0:
+			break;
+		default:
+			pr_warn("md: fatal superblock inconsistency in %pg -- removing from array\n",
+				rdev->bdev);
+			md_kick_rdev_from_array(rdev);
+		}
+
+	/* Cannot find a valid fresh disk */
+	if (!freshest) {
+		pr_warn("md: cannot find a valid disk\n");
+		return -EINVAL;
+	}
+
+	super_types[mddev->major_version].
+		validate_super(mddev, NULL/*freshest*/, freshest);
+
+	rdev_for_each_safe(rdev, tmp, mddev) {
+		if (mddev->max_disks &&
+		    rdev->desc_nr >= mddev->max_disks) {
+			pr_warn("md: %s: %pg: only %d devices permitted\n",
+				mdname(mddev), rdev->bdev,
+				mddev->max_disks);
+			md_kick_rdev_from_array(rdev);
+			continue;
+		}
+		if (rdev != freshest) {
+			if (super_types[mddev->major_version].
+			    validate_super(mddev, freshest, rdev)) {
+				pr_warn("md: kicking non-fresh %pg from array!\n",
+					rdev->bdev);
+				md_kick_rdev_from_array(rdev);
+				continue;
+			}
+		}
+		if (rdev->raid_disk >= (mddev->raid_disks - min(0, mddev->delta_disks)) &&
+		    !test_bit(Journal, &rdev->flags)) {
+			rdev->raid_disk = -1;
+			clear_bit(In_sync, &rdev->flags);
+		}
+	}
+
+	return 0;
+}
+
+/* Read a fixed-point number.
+ * Numbers in sysfs attributes should be in "standard" units where
+ * possible, so time should be in seconds.
+ * However we internally use a a much smaller unit such as
+ * milliseconds or jiffies.
+ * This function takes a decimal number with a possible fractional
+ * component, and produces an integer which is the result of
+ * multiplying that number by 10^'scale'.
+ * all without any floating-point arithmetic.
+ */
+int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale)
+{
+	unsigned long result = 0;
+	long decimals = -1;
+	while (isdigit(*cp) || (*cp == '.' && decimals < 0)) {
+		if (*cp == '.')
+			decimals = 0;
+		else if (decimals < scale) {
+			unsigned int value;
+			value = *cp - '0';
+			result = result * 10 + value;
+			if (decimals >= 0)
+				decimals++;
+		}
+		cp++;
+	}
+	if (*cp == '\n')
+		cp++;
+	if (*cp)
+		return -EINVAL;
+	if (decimals < 0)
+		decimals = 0;
+	*res = result * int_pow(10, scale - decimals);
+	return 0;
+}
+
+static ssize_t
+safe_delay_show(struct mddev *mddev, char *page)
+{
+	unsigned int msec = ((unsigned long)mddev->safemode_delay*1000)/HZ;
+
+	return sprintf(page, "%u.%03u\n", msec/1000, msec%1000);
+}
+static ssize_t
+safe_delay_store(struct mddev *mddev, const char *cbuf, size_t len)
+{
+	unsigned long msec;
+
+	if (mddev_is_clustered(mddev)) {
+		pr_warn("md: Safemode is disabled for clustered mode\n");
+		return -EINVAL;
+	}
+
+	if (strict_strtoul_scaled(cbuf, &msec, 3) < 0 || msec > UINT_MAX / HZ)
+		return -EINVAL;
+	if (msec == 0)
+		mddev->safemode_delay = 0;
+	else {
+		unsigned long old_delay = mddev->safemode_delay;
+		unsigned long new_delay = (msec*HZ)/1000;
+
+		if (new_delay == 0)
+			new_delay = 1;
+		mddev->safemode_delay = new_delay;
+		if (new_delay < old_delay || old_delay == 0)
+			mod_timer(&mddev->safemode_timer, jiffies+1);
+	}
+	return len;
+}
+static struct md_sysfs_entry md_safe_delay =
+__ATTR(safe_mode_delay, S_IRUGO|S_IWUSR,safe_delay_show, safe_delay_store);
+
+static ssize_t
+level_show(struct mddev *mddev, char *page)
+{
+	struct md_personality *p;
+	int ret;
+	spin_lock(&mddev->lock);
+	p = mddev->pers;
+	if (p)
+		ret = sprintf(page, "%s\n", p->head.name);
+	else if (mddev->clevel[0])
+		ret = sprintf(page, "%s\n", mddev->clevel);
+	else if (mddev->level != LEVEL_NONE)
+		ret = sprintf(page, "%d\n", mddev->level);
+	else
+		ret = 0;
+	spin_unlock(&mddev->lock);
+	return ret;
+}
+
+static ssize_t
+level_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	char clevel[16];
+	ssize_t rv;
+	size_t slen = len;
+	unsigned int noio_flags;
+	struct md_personality *pers, *oldpers;
+	long level;
+	void *priv, *oldpriv;
+	struct md_rdev *rdev;
+
+	if (slen == 0 || slen >= sizeof(clevel))
+		return -EINVAL;
+
+	rv = mddev_suspend_and_lock(mddev);
+	if (rv)
+		return rv;
+	noio_flags = memalloc_noio_save();
+
+	if (mddev->pers == NULL) {
+		memcpy(mddev->clevel, buf, slen);
+		if (mddev->clevel[slen-1] == '\n')
+			slen--;
+		mddev->clevel[slen] = 0;
+		mddev->level = LEVEL_NONE;
+		rv = len;
+		goto out_unlock;
+	}
+	rv = -EROFS;
+	if (!md_is_rdwr(mddev))
+		goto out_unlock;
+
+	/* request to change the personality.  Need to ensure:
+	 *  - array is not engaged in resync/recovery/reshape
+	 *  - old personality can be suspended
+	 *  - new personality will access other array.
+	 */
+
+	rv = -EBUSY;
+	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
+	    mddev->reshape_position != MaxSector ||
+	    mddev->sysfs_active)
+		goto out_unlock;
+
+	rv = -EINVAL;
+	if (!mddev->pers->quiesce) {
+		pr_warn("md: %s: %s does not support online personality change\n",
+			mdname(mddev), mddev->pers->head.name);
+		goto out_unlock;
+	}
+
+	/* Now find the new personality */
+	memcpy(clevel, buf, slen);
+	if (clevel[slen-1] == '\n')
+		slen--;
+	clevel[slen] = 0;
+	if (kstrtol(clevel, 10, &level))
+		level = LEVEL_NONE;
+
+	if (request_module("md-%s", clevel) != 0)
+		request_module("md-level-%s", clevel);
+	pers = get_pers(level, clevel);
+	if (!pers) {
+		rv = -EINVAL;
+		goto out_unlock;
+	}
+
+	if (pers == mddev->pers) {
+		/* Nothing to do! */
+		put_pers(pers);
+		rv = len;
+		goto out_unlock;
+	}
+	if (!pers->takeover) {
+		put_pers(pers);
+		pr_warn("md: %s: %s does not support personality takeover\n",
+			mdname(mddev), clevel);
+		rv = -EINVAL;
+		goto out_unlock;
+	}
+
+	rdev_for_each(rdev, mddev)
+		rdev->new_raid_disk = rdev->raid_disk;
+
+	/* ->takeover must set new_* and/or delta_disks
+	 * if it succeeds, and may set them when it fails.
+	 */
+	priv = pers->takeover(mddev);
+	if (IS_ERR(priv)) {
+		mddev->new_level = mddev->level;
+		mddev->new_layout = mddev->layout;
+		mddev->new_chunk_sectors = mddev->chunk_sectors;
+		mddev->raid_disks -= mddev->delta_disks;
+		mddev->delta_disks = 0;
+		mddev->reshape_backwards = 0;
+		put_pers(pers);
+		pr_warn("md: %s: %s would not accept array\n",
+			mdname(mddev), clevel);
+		rv = PTR_ERR(priv);
+		goto out_unlock;
+	}
+
+	/* Looks like we have a winner */
+	mddev_detach(mddev);
+
+	spin_lock(&mddev->lock);
+	oldpers = mddev->pers;
+	oldpriv = mddev->private;
+	mddev->pers = pers;
+	mddev->private = priv;
+	strscpy(mddev->clevel, pers->head.name, sizeof(mddev->clevel));
+	mddev->level = mddev->new_level;
+	mddev->layout = mddev->new_layout;
+	mddev->chunk_sectors = mddev->new_chunk_sectors;
+	mddev->delta_disks = 0;
+	mddev->reshape_backwards = 0;
+	mddev->degraded = 0;
+	spin_unlock(&mddev->lock);
+
+	if (oldpers->sync_request == NULL &&
+	    mddev->external) {
+		/* We are converting from a no-redundancy array
+		 * to a redundancy array and metadata is managed
+		 * externally so we need to be sure that writes
+		 * won't block due to a need to transition
+		 *      clean->dirty
+		 * until external management is started.
+		 */
+		mddev->in_sync = 0;
+		mddev->safemode_delay = 0;
+		mddev->safemode = 0;
+	}
+
+	oldpers->free(mddev, oldpriv);
+
+	if (oldpers->sync_request == NULL &&
+	    pers->sync_request != NULL) {
+		/* need to add the md_redundancy_group */
+		if (sysfs_create_group(&mddev->kobj, &md_redundancy_group))
+			pr_warn("md: cannot register extra attributes for %s\n",
+				mdname(mddev));
+		mddev->sysfs_action = sysfs_get_dirent(mddev->kobj.sd, "sync_action");
+		mddev->sysfs_completed = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_completed");
+		mddev->sysfs_degraded = sysfs_get_dirent_safe(mddev->kobj.sd, "degraded");
+	}
+	if (oldpers->sync_request != NULL &&
+	    pers->sync_request == NULL) {
+		/* need to remove the md_redundancy_group */
+		if (mddev->to_remove == NULL)
+			mddev->to_remove = &md_redundancy_group;
+	}
+
+	put_pers(oldpers);
+
+	rdev_for_each(rdev, mddev) {
+		if (rdev->raid_disk < 0)
+			continue;
+		if (rdev->new_raid_disk >= mddev->raid_disks)
+			rdev->new_raid_disk = -1;
+		if (rdev->new_raid_disk == rdev->raid_disk)
+			continue;
+		sysfs_unlink_rdev(mddev, rdev);
+	}
+	rdev_for_each(rdev, mddev) {
+		if (rdev->raid_disk < 0)
+			continue;
+		if (rdev->new_raid_disk == rdev->raid_disk)
+			continue;
+		rdev->raid_disk = rdev->new_raid_disk;
+		if (rdev->raid_disk < 0)
+			clear_bit(In_sync, &rdev->flags);
+		else {
+			if (sysfs_link_rdev(mddev, rdev))
+				pr_warn("md: cannot register rd%d for %s after level change\n",
+					rdev->raid_disk, mdname(mddev));
+		}
+	}
+
+	if (pers->sync_request == NULL) {
+		/* this is now an array without redundancy, so
+		 * it must always be in_sync
+		 */
+		mddev->in_sync = 1;
+		timer_delete_sync(&mddev->safemode_timer);
+	}
+	pers->run(mddev);
+	set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
+	if (!mddev->thread)
+		md_update_sb(mddev, 1);
+	sysfs_notify_dirent_safe(mddev->sysfs_level);
+	md_new_event();
+	rv = len;
+out_unlock:
+	memalloc_noio_restore(noio_flags);
+	mddev_unlock_and_resume(mddev);
+	return rv;
+}
+
+static struct md_sysfs_entry md_level =
+__ATTR(level, S_IRUGO|S_IWUSR, level_show, level_store);
+
+static ssize_t
+new_level_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%d\n", mddev->new_level);
+}
+
+static ssize_t
+new_level_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	unsigned int n;
+	int err;
+
+	err = kstrtouint(buf, 10, &n);
+	if (err < 0)
+		return err;
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+
+	mddev->new_level = n;
+	md_update_sb(mddev, 1);
+
+	mddev_unlock(mddev);
+	return len;
+}
+static struct md_sysfs_entry md_new_level =
+__ATTR(new_level, 0664, new_level_show, new_level_store);
+
+static ssize_t
+bitmap_type_show(struct mddev *mddev, char *page)
+{
+	struct md_submodule_head *head;
+	unsigned long i;
+	ssize_t len = 0;
+
+	if (mddev->bitmap_id == ID_BITMAP_NONE)
+		len += sprintf(page + len, "[none] ");
+	else
+		len += sprintf(page + len, "none ");
+
+	xa_lock(&md_submodule);
+	xa_for_each(&md_submodule, i, head) {
+		if (head->type != MD_BITMAP || head->id == ID_BITMAP_NONE)
+			continue;
+
+		if (mddev->bitmap_id == head->id)
+			len += sprintf(page + len, "[%s] ", head->name);
+		else
+			len += sprintf(page + len, "%s ", head->name);
+	}
+	xa_unlock(&md_submodule);
+
+	len += sprintf(page + len, "\n");
+	return len;
+}
+
+static ssize_t
+bitmap_type_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	struct md_submodule_head *head;
+	enum md_submodule_id id;
+	unsigned long i;
+	int err = 0;
+
+	xa_lock(&md_submodule);
+
+	if (mddev->bitmap_ops) {
+		err = -EBUSY;
+		goto out;
+	}
+
+	if (cmd_match(buf, "none")) {
+		mddev->bitmap_id = ID_BITMAP_NONE;
+		goto out;
+	}
+
+	xa_for_each(&md_submodule, i, head) {
+		if (head->type == MD_BITMAP && cmd_match(buf, head->name)) {
+			mddev->bitmap_id = head->id;
+			goto out;
+		}
+	}
+
+	err = kstrtoint(buf, 10, &id);
+	if (err)
+		goto out;
+
+	if (id == ID_BITMAP_NONE) {
+		mddev->bitmap_id = id;
+		goto out;
+	}
+
+	head = xa_load(&md_submodule, id);
+	if (head && head->type == MD_BITMAP) {
+		mddev->bitmap_id = id;
+		goto out;
+	}
+
+	err = -ENOENT;
+
+out:
+	xa_unlock(&md_submodule);
+	return err ? err : len;
+}
+
+static struct md_sysfs_entry md_bitmap_type =
+__ATTR(bitmap_type, 0664, bitmap_type_show, bitmap_type_store);
+
+static ssize_t
+layout_show(struct mddev *mddev, char *page)
+{
+	/* just a number, not meaningful for all levels */
+	if (mddev->reshape_position != MaxSector &&
+	    mddev->layout != mddev->new_layout)
+		return sprintf(page, "%d (%d)\n",
+			       mddev->new_layout, mddev->layout);
+	return sprintf(page, "%d\n", mddev->layout);
+}
+
+static ssize_t
+layout_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	unsigned int n;
+	int err;
+
+	err = kstrtouint(buf, 10, &n);
+	if (err < 0)
+		return err;
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+
+	if (mddev->pers) {
+		if (mddev->pers->check_reshape == NULL)
+			err = -EBUSY;
+		else if (!md_is_rdwr(mddev))
+			err = -EROFS;
+		else {
+			mddev->new_layout = n;
+			err = mddev->pers->check_reshape(mddev);
+			if (err)
+				mddev->new_layout = mddev->layout;
+		}
+	} else {
+		mddev->new_layout = n;
+		if (mddev->reshape_position == MaxSector)
+			mddev->layout = n;
+	}
+	mddev_unlock(mddev);
+	return err ?: len;
+}
+static struct md_sysfs_entry md_layout =
+__ATTR(layout, S_IRUGO|S_IWUSR, layout_show, layout_store);
+
+static ssize_t
+raid_disks_show(struct mddev *mddev, char *page)
+{
+	if (mddev->raid_disks == 0)
+		return 0;
+	if (mddev->reshape_position != MaxSector &&
+	    mddev->delta_disks != 0)
+		return sprintf(page, "%d (%d)\n", mddev->raid_disks,
+			       mddev->raid_disks - mddev->delta_disks);
+	return sprintf(page, "%d\n", mddev->raid_disks);
+}
+
+static int update_raid_disks(struct mddev *mddev, int raid_disks);
+
+static ssize_t
+raid_disks_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	unsigned int n;
+	unsigned int noio_flags;
+	int err;
+
+	err = kstrtouint(buf, 10, &n);
+	if (err < 0)
+		return err;
+
+	err = mddev_suspend_and_lock(mddev);
+	if (err)
+		return err;
+	noio_flags = memalloc_noio_save();
+	if (mddev->pers) {
+		if (n != mddev->raid_disks)
+			err = update_raid_disks(mddev, n);
+	} else if (mddev->reshape_position != MaxSector) {
+		struct md_rdev *rdev;
+		int olddisks = mddev->raid_disks - mddev->delta_disks;
+
+		err = -EINVAL;
+		rdev_for_each(rdev, mddev) {
+			if (olddisks < n &&
+			    rdev->data_offset < rdev->new_data_offset)
+				goto out_unlock;
+			if (olddisks > n &&
+			    rdev->data_offset > rdev->new_data_offset)
+				goto out_unlock;
+		}
+		err = 0;
+		mddev->delta_disks = n - olddisks;
+		mddev->raid_disks = n;
+		mddev->reshape_backwards = (mddev->delta_disks < 0);
+	} else
+		mddev->raid_disks = n;
+out_unlock:
+	memalloc_noio_restore(noio_flags);
+	mddev_unlock_and_resume(mddev);
+	return err ? err : len;
+}
+static struct md_sysfs_entry md_raid_disks =
+__ATTR(raid_disks, S_IRUGO|S_IWUSR, raid_disks_show, raid_disks_store);
+
+static ssize_t
+uuid_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%pU\n", mddev->uuid);
+}
+static struct md_sysfs_entry md_uuid =
+__ATTR(uuid, S_IRUGO, uuid_show, NULL);
+
+static ssize_t
+chunk_size_show(struct mddev *mddev, char *page)
+{
+	if (mddev->reshape_position != MaxSector &&
+	    mddev->chunk_sectors != mddev->new_chunk_sectors)
+		return sprintf(page, "%d (%d)\n",
+			       mddev->new_chunk_sectors << 9,
+			       mddev->chunk_sectors << 9);
+	return sprintf(page, "%d\n", mddev->chunk_sectors << 9);
+}
+
+static ssize_t
+chunk_size_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	unsigned long n;
+	int err;
+
+	err = kstrtoul(buf, 10, &n);
+	if (err < 0)
+		return err;
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	if (mddev->pers) {
+		if (mddev->pers->check_reshape == NULL)
+			err = -EBUSY;
+		else if (!md_is_rdwr(mddev))
+			err = -EROFS;
+		else {
+			mddev->new_chunk_sectors = n >> 9;
+			err = mddev->pers->check_reshape(mddev);
+			if (err)
+				mddev->new_chunk_sectors = mddev->chunk_sectors;
+		}
+	} else {
+		mddev->new_chunk_sectors = n >> 9;
+		if (mddev->reshape_position == MaxSector)
+			mddev->chunk_sectors = n >> 9;
+	}
+	mddev_unlock(mddev);
+	return err ?: len;
+}
+static struct md_sysfs_entry md_chunk_size =
+__ATTR(chunk_size, S_IRUGO|S_IWUSR, chunk_size_show, chunk_size_store);
+
+static ssize_t
+resync_start_show(struct mddev *mddev, char *page)
+{
+	if (mddev->resync_offset == MaxSector)
+		return sprintf(page, "none\n");
+	return sprintf(page, "%llu\n", (unsigned long long)mddev->resync_offset);
+}
+
+static ssize_t
+resync_start_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	unsigned long long n;
+	int err;
+
+	if (cmd_match(buf, "none"))
+		n = MaxSector;
+	else {
+		err = kstrtoull(buf, 10, &n);
+		if (err < 0)
+			return err;
+		if (n != (sector_t)n)
+			return -EINVAL;
+	}
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	if (mddev->pers && !test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
+		err = -EBUSY;
+
+	if (!err) {
+		mddev->resync_offset = n;
+		if (mddev->pers)
+			set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
+	}
+	mddev_unlock(mddev);
+	return err ?: len;
+}
+static struct md_sysfs_entry md_resync_start =
+__ATTR_PREALLOC(resync_start, S_IRUGO|S_IWUSR,
+		resync_start_show, resync_start_store);
+
+/*
+ * The array state can be:
+ *
+ * clear
+ *     No devices, no size, no level
+ *     Equivalent to STOP_ARRAY ioctl
+ * inactive
+ *     May have some settings, but array is not active
+ *        all IO results in error
+ *     When written, doesn't tear down array, but just stops it
+ * suspended (not supported yet)
+ *     All IO requests will block. The array can be reconfigured.
+ *     Writing this, if accepted, will block until array is quiescent
+ * readonly
+ *     no resync can happen.  no superblocks get written.
+ *     write requests fail
+ * read-auto
+ *     like readonly, but behaves like 'clean' on a write request.
+ *
+ * clean - no pending writes, but otherwise active.
+ *     When written to inactive array, starts without resync
+ *     If a write request arrives then
+ *       if metadata is known, mark 'dirty' and switch to 'active'.
+ *       if not known, block and switch to write-pending
+ *     If written to an active array that has pending writes, then fails.
+ * active
+ *     fully active: IO and resync can be happening.
+ *     When written to inactive array, starts with resync
+ *
+ * write-pending
+ *     clean, but writes are blocked waiting for 'active' to be written.
+ *
+ * active-idle
+ *     like active, but no writes have been seen for a while (100msec).
+ *
+ * broken
+*     Array is failed. It's useful because mounted-arrays aren't stopped
+*     when array is failed, so this state will at least alert the user that
+*     something is wrong.
+ */
+enum array_state { clear, inactive, suspended, readonly, read_auto, clean, active,
+		   write_pending, active_idle, broken, bad_word};
+static char *array_states[] = {
+	"clear", "inactive", "suspended", "readonly", "read-auto", "clean", "active",
+	"write-pending", "active-idle", "broken", NULL };
+
+static int match_word(const char *word, char **list)
+{
+	int n;
+	for (n=0; list[n]; n++)
+		if (cmd_match(word, list[n]))
+			break;
+	return n;
+}
+
+static ssize_t
+array_state_show(struct mddev *mddev, char *page)
+{
+	enum array_state st = inactive;
+
+	if (mddev->pers && !test_bit(MD_NOT_READY, &mddev->flags)) {
+		switch(mddev->ro) {
+		case MD_RDONLY:
+			st = readonly;
+			break;
+		case MD_AUTO_READ:
+			st = read_auto;
+			break;
+		case MD_RDWR:
+			spin_lock(&mddev->lock);
+			if (test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags))
+				st = write_pending;
+			else if (mddev->in_sync)
+				st = clean;
+			else if (mddev->safemode)
+				st = active_idle;
+			else
+				st = active;
+			spin_unlock(&mddev->lock);
+		}
+
+		if (test_bit(MD_BROKEN, &mddev->flags) && st == clean)
+			st = broken;
+	} else {
+		if (list_empty(&mddev->disks) &&
+		    mddev->raid_disks == 0 &&
+		    mddev->dev_sectors == 0)
+			st = clear;
+		else
+			st = inactive;
+	}
+	return sprintf(page, "%s\n", array_states[st]);
+}
+
+static int do_md_stop(struct mddev *mddev, int ro);
+static int md_set_readonly(struct mddev *mddev);
+static int restart_array(struct mddev *mddev);
+
+static ssize_t
+array_state_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	int err = 0;
+	enum array_state st = match_word(buf, array_states);
+
+	/* No lock dependent actions */
+	switch (st) {
+	case suspended:		/* not supported yet */
+	case write_pending:	/* cannot be set */
+	case active_idle:	/* cannot be set */
+	case broken:		/* cannot be set */
+	case bad_word:
+		return -EINVAL;
+	case clear:
+	case readonly:
+	case inactive:
+	case read_auto:
+		if (!mddev->pers || !md_is_rdwr(mddev))
+			break;
+		/* write sysfs will not open mddev and opener should be 0 */
+		err = mddev_set_closing_and_sync_blockdev(mddev, 0);
+		if (err)
+			return err;
+		break;
+	default:
+		break;
+	}
+
+	if (mddev->pers && (st == active || st == clean) &&
+	    mddev->ro != MD_RDONLY) {
+		/* don't take reconfig_mutex when toggling between
+		 * clean and active
+		 */
+		spin_lock(&mddev->lock);
+		if (st == active) {
+			restart_array(mddev);
+			clear_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
+			md_wakeup_thread(mddev->thread);
+			wake_up(&mddev->sb_wait);
+		} else /* st == clean */ {
+			restart_array(mddev);
+			if (!set_in_sync(mddev))
+				err = -EBUSY;
+		}
+		if (!err)
+			sysfs_notify_dirent_safe(mddev->sysfs_state);
+		spin_unlock(&mddev->lock);
+		return err ?: len;
+	}
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+
+	switch (st) {
+	case inactive:
+		/* stop an active array, return 0 otherwise */
+		if (mddev->pers)
+			err = do_md_stop(mddev, 2);
+		break;
+	case clear:
+		err = do_md_stop(mddev, 0);
+		break;
+	case readonly:
+		if (mddev->pers)
+			err = md_set_readonly(mddev);
+		else {
+			mddev->ro = MD_RDONLY;
+			set_disk_ro(mddev->gendisk, 1);
+			err = do_md_run(mddev);
+		}
+		break;
+	case read_auto:
+		if (mddev->pers) {
+			if (md_is_rdwr(mddev))
+				err = md_set_readonly(mddev);
+			else if (mddev->ro == MD_RDONLY)
+				err = restart_array(mddev);
+			if (err == 0) {
+				mddev->ro = MD_AUTO_READ;
+				set_disk_ro(mddev->gendisk, 0);
+			}
+		} else {
+			mddev->ro = MD_AUTO_READ;
+			err = do_md_run(mddev);
+		}
+		break;
+	case clean:
+		if (mddev->pers) {
+			err = restart_array(mddev);
+			if (err)
+				break;
+			spin_lock(&mddev->lock);
+			if (!set_in_sync(mddev))
+				err = -EBUSY;
+			spin_unlock(&mddev->lock);
+		} else
+			err = -EINVAL;
+		break;
+	case active:
+		if (mddev->pers) {
+			err = restart_array(mddev);
+			if (err)
+				break;
+			clear_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
+			wake_up(&mddev->sb_wait);
+			err = 0;
+		} else {
+			mddev->ro = MD_RDWR;
+			set_disk_ro(mddev->gendisk, 0);
+			err = do_md_run(mddev);
+		}
+		break;
+	default:
+		err = -EINVAL;
+		break;
+	}
+
+	if (!err) {
+		if (mddev->hold_active == UNTIL_IOCTL)
+			mddev->hold_active = 0;
+		sysfs_notify_dirent_safe(mddev->sysfs_state);
+	}
+	mddev_unlock(mddev);
+
+	if (st == readonly || st == read_auto || st == inactive ||
+	    (err && st == clear))
+		clear_bit(MD_CLOSING, &mddev->flags);
+
+	return err ?: len;
+}
+static struct md_sysfs_entry md_array_state =
+__ATTR_PREALLOC(array_state, S_IRUGO|S_IWUSR, array_state_show, array_state_store);
+
+static ssize_t
+max_corrected_read_errors_show(struct mddev *mddev, char *page) {
+	return sprintf(page, "%d\n",
+		       atomic_read(&mddev->max_corr_read_errors));
+}
+
+static ssize_t
+max_corrected_read_errors_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	unsigned int n;
+	int rv;
+
+	rv = kstrtouint(buf, 10, &n);
+	if (rv < 0)
+		return rv;
+	if (n > INT_MAX)
+		return -EINVAL;
+	atomic_set(&mddev->max_corr_read_errors, n);
+	return len;
+}
+
+static struct md_sysfs_entry max_corr_read_errors =
+__ATTR(max_read_errors, S_IRUGO|S_IWUSR, max_corrected_read_errors_show,
+	max_corrected_read_errors_store);
+
+static ssize_t
+null_show(struct mddev *mddev, char *page)
+{
+	return -EINVAL;
+}
+
+static ssize_t
+new_dev_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	/* buf must be %d:%d\n? giving major and minor numbers */
+	/* The new device is added to the array.
+	 * If the array has a persistent superblock, we read the
+	 * superblock to initialise info and check validity.
+	 * Otherwise, only checking done is that in bind_rdev_to_array,
+	 * which mainly checks size.
+	 */
+	char *e;
+	int major = simple_strtoul(buf, &e, 10);
+	int minor;
+	dev_t dev;
+	struct md_rdev *rdev;
+	unsigned int noio_flags;
+	int err;
+
+	if (!*buf || *e != ':' || !e[1] || e[1] == '\n')
+		return -EINVAL;
+	minor = simple_strtoul(e+1, &e, 10);
+	if (*e && *e != '\n')
+		return -EINVAL;
+	dev = MKDEV(major, minor);
+	if (major != MAJOR(dev) ||
+	    minor != MINOR(dev))
+		return -EOVERFLOW;
+
+	err = mddev_suspend_and_lock(mddev);
+	if (err)
+		return err;
+	noio_flags = memalloc_noio_save();
+	if (mddev->persistent) {
+		rdev = md_import_device(dev, mddev->major_version,
+					mddev->minor_version);
+		if (!IS_ERR(rdev) && !list_empty(&mddev->disks)) {
+			struct md_rdev *rdev0
+				= list_entry(mddev->disks.next,
+					     struct md_rdev, same_set);
+			err = super_types[mddev->major_version]
+				.load_super(rdev, rdev0, mddev->minor_version);
+			if (err < 0)
+				goto out;
+		}
+	} else if (mddev->external)
+		rdev = md_import_device(dev, -2, -1);
+	else
+		rdev = md_import_device(dev, -1, -1);
+
+	if (IS_ERR(rdev)) {
+		memalloc_noio_restore(noio_flags);
+		mddev_unlock_and_resume(mddev);
+		return PTR_ERR(rdev);
+	}
+	err = bind_rdev_to_array(rdev, mddev);
+ out:
+	if (err)
+		export_rdev(rdev);
+	memalloc_noio_restore(noio_flags);
+	mddev_unlock_and_resume(mddev);
+	if (!err)
+		md_new_event();
+	return err ? err : len;
+}
+
+static struct md_sysfs_entry md_new_device =
+__ATTR(new_dev, S_IWUSR, null_show, new_dev_store);
+
+static ssize_t
+bitmap_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	char *end;
+	unsigned long chunk, end_chunk;
+	int err;
+
+	if (!md_bitmap_enabled(mddev, false))
+		return len;
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	if (!mddev->bitmap)
+		goto out;
+	/* buf should be <chunk> <chunk> ... or <chunk>-<chunk> ... (range) */
+	while (*buf) {
+		chunk = end_chunk = simple_strtoul(buf, &end, 0);
+		if (buf == end)
+			break;
+
+		if (*end == '-') { /* range */
+			buf = end + 1;
+			end_chunk = simple_strtoul(buf, &end, 0);
+			if (buf == end)
+				break;
+		}
+
+		if (*end && !isspace(*end))
+			break;
+
+		mddev->bitmap_ops->dirty_bits(mddev, chunk, end_chunk);
+		buf = skip_spaces(end);
+	}
+	mddev->bitmap_ops->unplug(mddev, true); /* flush the bits to disk */
+out:
+	mddev_unlock(mddev);
+	return len;
+}
+
+static struct md_sysfs_entry md_bitmap =
+__ATTR(bitmap_set_bits, S_IWUSR, null_show, bitmap_store);
+
+static ssize_t
+size_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%llu\n",
+		(unsigned long long)mddev->dev_sectors / 2);
+}
+
+static int update_size(struct mddev *mddev, sector_t num_sectors);
+
+static ssize_t
+size_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	/* If array is inactive, we can reduce the component size, but
+	 * not increase it (except from 0).
+	 * If array is active, we can try an on-line resize
+	 */
+	sector_t sectors;
+	int err = strict_blocks_to_sectors(buf, &sectors);
+
+	if (err < 0)
+		return err;
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	if (mddev->pers) {
+		err = update_size(mddev, sectors);
+		if (err == 0)
+			md_update_sb(mddev, 1);
+	} else {
+		if (mddev->dev_sectors == 0 ||
+		    mddev->dev_sectors > sectors)
+			mddev->dev_sectors = sectors;
+		else
+			err = -ENOSPC;
+	}
+	mddev_unlock(mddev);
+	return err ? err : len;
+}
+
+static struct md_sysfs_entry md_size =
+__ATTR(component_size, S_IRUGO|S_IWUSR, size_show, size_store);
+
+/* Metadata version.
+ * This is one of
+ *   'none' for arrays with no metadata (good luck...)
+ *   'external' for arrays with externally managed metadata,
+ * or N.M for internally known formats
+ */
+static ssize_t
+metadata_show(struct mddev *mddev, char *page)
+{
+	if (mddev->persistent)
+		return sprintf(page, "%d.%d\n",
+			       mddev->major_version, mddev->minor_version);
+	else if (mddev->external)
+		return sprintf(page, "external:%s\n", mddev->metadata_type);
+	else
+		return sprintf(page, "none\n");
+}
+
+static ssize_t
+metadata_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	int major, minor;
+	char *e;
+	int err;
+	/* Changing the details of 'external' metadata is
+	 * always permitted.  Otherwise there must be
+	 * no devices attached to the array.
+	 */
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	err = -EBUSY;
+	if (mddev->external && strncmp(buf, "external:", 9) == 0)
+		;
+	else if (!list_empty(&mddev->disks))
+		goto out_unlock;
+
+	err = 0;
+	if (cmd_match(buf, "none")) {
+		mddev->persistent = 0;
+		mddev->external = 0;
+		mddev->major_version = 0;
+		mddev->minor_version = 90;
+		goto out_unlock;
+	}
+	if (strncmp(buf, "external:", 9) == 0) {
+		size_t namelen = len-9;
+		if (namelen >= sizeof(mddev->metadata_type))
+			namelen = sizeof(mddev->metadata_type)-1;
+		memcpy(mddev->metadata_type, buf+9, namelen);
+		mddev->metadata_type[namelen] = 0;
+		if (namelen && mddev->metadata_type[namelen-1] == '\n')
+			mddev->metadata_type[--namelen] = 0;
+		mddev->persistent = 0;
+		mddev->external = 1;
+		mddev->major_version = 0;
+		mddev->minor_version = 90;
+		goto out_unlock;
+	}
+	major = simple_strtoul(buf, &e, 10);
+	err = -EINVAL;
+	if (e==buf || *e != '.')
+		goto out_unlock;
+	buf = e+1;
+	minor = simple_strtoul(buf, &e, 10);
+	if (e==buf || (*e && *e != '\n') )
+		goto out_unlock;
+	err = -ENOENT;
+	if (major >= ARRAY_SIZE(super_types) || super_types[major].name == NULL)
+		goto out_unlock;
+	mddev->major_version = major;
+	mddev->minor_version = minor;
+	mddev->persistent = 1;
+	mddev->external = 0;
+	err = 0;
+out_unlock:
+	mddev_unlock(mddev);
+	return err ?: len;
+}
+
+static struct md_sysfs_entry md_metadata =
+__ATTR_PREALLOC(metadata_version, S_IRUGO|S_IWUSR, metadata_show, metadata_store);
+
+static bool rdev_needs_recovery(struct md_rdev *rdev, sector_t sectors)
+{
+	return rdev->raid_disk >= 0 &&
+	       !test_bit(Journal, &rdev->flags) &&
+	       !test_bit(Faulty, &rdev->flags) &&
+	       !test_bit(In_sync, &rdev->flags) &&
+	       rdev->recovery_offset < sectors;
+}
+
+static enum sync_action md_get_active_sync_action(struct mddev *mddev)
+{
+	struct md_rdev *rdev;
+	bool is_recover = false;
+
+	if (mddev->resync_offset < MaxSector)
+		return ACTION_RESYNC;
+
+	if (mddev->reshape_position != MaxSector)
+		return ACTION_RESHAPE;
+
+	rcu_read_lock();
+	rdev_for_each_rcu(rdev, mddev) {
+		if (rdev_needs_recovery(rdev, MaxSector)) {
+			is_recover = true;
+			break;
+		}
+	}
+	rcu_read_unlock();
+
+	return is_recover ? ACTION_RECOVER : ACTION_IDLE;
+}
+
+enum sync_action md_sync_action(struct mddev *mddev)
+{
+	unsigned long recovery = mddev->recovery;
+	enum sync_action active_action;
+
+	/*
+	 * frozen has the highest priority, means running sync_thread will be
+	 * stopped immediately, and no new sync_thread can start.
+	 */
+	if (test_bit(MD_RECOVERY_FROZEN, &recovery))
+		return ACTION_FROZEN;
+
+	/*
+	 * read-only array can't register sync_thread, and it can only
+	 * add/remove spares.
+	 */
+	if (!md_is_rdwr(mddev))
+		return ACTION_IDLE;
+
+	/*
+	 * idle means no sync_thread is running, and no new sync_thread is
+	 * requested.
+	 */
+	if (!test_bit(MD_RECOVERY_RUNNING, &recovery) &&
+	    !test_bit(MD_RECOVERY_NEEDED, &recovery))
+		return ACTION_IDLE;
+
+	/*
+	 * Check if any sync operation (resync/recover/reshape) is
+	 * currently active. This ensures that only one sync operation
+	 * can run at a time. Returns the type of active operation, or
+	 * ACTION_IDLE if none are active.
+	 */
+	active_action = md_get_active_sync_action(mddev);
+	if (active_action != ACTION_IDLE)
+		return active_action;
+
+	if (test_bit(MD_RECOVERY_RESHAPE, &recovery))
+		return ACTION_RESHAPE;
+
+	if (test_bit(MD_RECOVERY_RECOVER, &recovery))
+		return ACTION_RECOVER;
+
+	if (test_bit(MD_RECOVERY_SYNC, &recovery)) {
+		/*
+		 * MD_RECOVERY_CHECK must be paired with
+		 * MD_RECOVERY_REQUESTED.
+		 */
+		if (test_bit(MD_RECOVERY_CHECK, &recovery))
+			return ACTION_CHECK;
+		if (test_bit(MD_RECOVERY_REQUESTED, &recovery))
+			return ACTION_REPAIR;
+		return ACTION_RESYNC;
+	}
+
+	/*
+	 * MD_RECOVERY_NEEDED or MD_RECOVERY_RUNNING is set, however, no
+	 * sync_action is specified.
+	 */
+	return ACTION_IDLE;
+}
+
+enum sync_action md_sync_action_by_name(const char *page)
+{
+	enum sync_action action;
+
+	for (action = 0; action < NR_SYNC_ACTIONS; ++action) {
+		if (cmd_match(page, action_name[action]))
+			return action;
+	}
+
+	return NR_SYNC_ACTIONS;
+}
+
+const char *md_sync_action_name(enum sync_action action)
+{
+	return action_name[action];
+}
+
+static ssize_t
+action_show(struct mddev *mddev, char *page)
+{
+	enum sync_action action = md_sync_action(mddev);
+
+	return sprintf(page, "%s\n", md_sync_action_name(action));
+}
+
+/**
+ * stop_sync_thread() - wait for sync_thread to stop if it's running.
+ * @mddev:	the array.
+ * @locked:	if set, reconfig_mutex will still be held after this function
+ *		return; if not set, reconfig_mutex will be released after this
+ *		function return.
+ */
+static void stop_sync_thread(struct mddev *mddev, bool locked)
+{
+	int sync_seq = atomic_read(&mddev->sync_seq);
+
+	if (!test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) {
+		if (!locked)
+			mddev_unlock(mddev);
+		return;
+	}
+
+	mddev_unlock(mddev);
+
+	set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+	/*
+	 * Thread might be blocked waiting for metadata update which will now
+	 * never happen
+	 */
+	md_wakeup_thread_directly(&mddev->sync_thread);
+	if (work_pending(&mddev->sync_work))
+		flush_work(&mddev->sync_work);
+
+	wait_event(resync_wait,
+		   !test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
+		   (!test_bit(MD_RECOVERY_FROZEN, &mddev->recovery) &&
+		    sync_seq != atomic_read(&mddev->sync_seq)));
+
+	if (locked)
+		mddev_lock_nointr(mddev);
+}
+
+void md_idle_sync_thread(struct mddev *mddev)
+{
+	lockdep_assert_held(&mddev->reconfig_mutex);
+
+	clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+	stop_sync_thread(mddev, true);
+}
+EXPORT_SYMBOL_GPL(md_idle_sync_thread);
+
+void md_frozen_sync_thread(struct mddev *mddev)
+{
+	lockdep_assert_held(&mddev->reconfig_mutex);
+
+	set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+	stop_sync_thread(mddev, true);
+}
+EXPORT_SYMBOL_GPL(md_frozen_sync_thread);
+
+void md_unfrozen_sync_thread(struct mddev *mddev)
+{
+	lockdep_assert_held(&mddev->reconfig_mutex);
+
+	clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	md_wakeup_thread(mddev->thread);
+	sysfs_notify_dirent_safe(mddev->sysfs_action);
+}
+EXPORT_SYMBOL_GPL(md_unfrozen_sync_thread);
+
+static int mddev_start_reshape(struct mddev *mddev)
+{
+	int ret;
+
+	if (mddev->pers->start_reshape == NULL)
+		return -EINVAL;
+
+	if (mddev->reshape_position == MaxSector ||
+	    mddev->pers->check_reshape == NULL ||
+	    mddev->pers->check_reshape(mddev)) {
+		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+		ret = mddev->pers->start_reshape(mddev);
+		if (ret)
+			return ret;
+	} else {
+		/*
+		 * If reshape is still in progress, and md_check_recovery() can
+		 * continue to reshape, don't restart reshape because data can
+		 * be corrupted for raid456.
+		 */
+		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+	}
+
+	sysfs_notify_dirent_safe(mddev->sysfs_degraded);
+	return 0;
+}
+
+static ssize_t
+action_store(struct mddev *mddev, const char *page, size_t len)
+{
+	int ret;
+	enum sync_action action;
+
+	if (!mddev->pers || !mddev->pers->sync_request)
+		return -EINVAL;
+
+	action = md_sync_action_by_name(page);
+	if (action == ACTION_RESHAPE) {
+		ret = mddev_suspend(mddev, true);
+		if (ret)
+			return ret;
+	}
+retry:
+	if (work_busy(&mddev->sync_work))
+		flush_work(&mddev->sync_work);
+
+	ret = mddev_lock(mddev);
+	if (ret) {
+		if (action == ACTION_RESHAPE)
+			mddev_resume(mddev);
+		return ret;
+	}
+
+	if (work_busy(&mddev->sync_work)) {
+		mddev_unlock(mddev);
+		goto retry;
+	}
+
+	/* TODO: mdadm rely on "idle" to start sync_thread. */
+	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) {
+		switch (action) {
+		case ACTION_FROZEN:
+			md_frozen_sync_thread(mddev);
+			ret = len;
+			goto out;
+		case ACTION_IDLE:
+			md_idle_sync_thread(mddev);
+			break;
+		case ACTION_RESHAPE:
+		case ACTION_RECOVER:
+		case ACTION_CHECK:
+		case ACTION_REPAIR:
+		case ACTION_RESYNC:
+			ret = -EBUSY;
+			goto out;
+		default:
+			ret = -EINVAL;
+			goto out;
+		}
+	} else {
+		switch (action) {
+		case ACTION_FROZEN:
+			set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+			ret = len;
+			goto out;
+		case ACTION_RESHAPE:
+			clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+			ret = mddev_start_reshape(mddev);
+			if (ret)
+				goto out;
+			break;
+		case ACTION_RECOVER:
+			clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+			set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
+			break;
+		case ACTION_CHECK:
+			set_bit(MD_RECOVERY_CHECK, &mddev->recovery);
+			fallthrough;
+		case ACTION_REPAIR:
+			set_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
+			set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+			fallthrough;
+		case ACTION_RESYNC:
+		case ACTION_IDLE:
+			clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+			break;
+		default:
+			ret = -EINVAL;
+			goto out;
+		}
+	}
+
+	if (mddev->ro == MD_AUTO_READ) {
+		/* A write to sync_action is enough to justify
+		 * canceling read-auto mode
+		 */
+		mddev->ro = MD_RDWR;
+		md_wakeup_thread(mddev->sync_thread);
+	}
+
+	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	md_wakeup_thread(mddev->thread);
+	sysfs_notify_dirent_safe(mddev->sysfs_action);
+	ret = len;
+
+out:
+	mddev_unlock(mddev);
+	if (action == ACTION_RESHAPE)
+		mddev_resume(mddev);
+	return ret;
+}
+
+static struct md_sysfs_entry md_scan_mode =
+__ATTR_PREALLOC(sync_action, S_IRUGO|S_IWUSR, action_show, action_store);
+
+static ssize_t
+last_sync_action_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%s\n",
+		       md_sync_action_name(mddev->last_sync_action));
+}
+
+static struct md_sysfs_entry md_last_scan_mode = __ATTR_RO(last_sync_action);
+
+static ssize_t
+mismatch_cnt_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%llu\n",
+		       (unsigned long long)
+		       atomic64_read(&mddev->resync_mismatches));
+}
+
+static struct md_sysfs_entry md_mismatches = __ATTR_RO(mismatch_cnt);
+
+static ssize_t
+sync_min_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%d (%s)\n", speed_min(mddev),
+		       mddev->sync_speed_min ? "local" : "system");
+}
+
+static ssize_t
+sync_min_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	unsigned int min;
+	int rv;
+
+	if (strncmp(buf, "system", 6) == 0) {
+		min = 0;
+	} else {
+		rv = kstrtouint(buf, 10, &min);
+		if (rv < 0)
+			return rv;
+		if (min == 0)
+			return -EINVAL;
+	}
+	mddev->sync_speed_min = min;
+	return len;
+}
+
+static struct md_sysfs_entry md_sync_min =
+__ATTR(sync_speed_min, S_IRUGO|S_IWUSR, sync_min_show, sync_min_store);
+
+static ssize_t
+sync_max_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%d (%s)\n", speed_max(mddev),
+		       mddev->sync_speed_max ? "local" : "system");
+}
+
+static ssize_t
+sync_max_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	unsigned int max;
+	int rv;
+
+	if (strncmp(buf, "system", 6) == 0) {
+		max = 0;
+	} else {
+		rv = kstrtouint(buf, 10, &max);
+		if (rv < 0)
+			return rv;
+		if (max == 0)
+			return -EINVAL;
+	}
+	mddev->sync_speed_max = max;
+	return len;
+}
+
+static struct md_sysfs_entry md_sync_max =
+__ATTR(sync_speed_max, S_IRUGO|S_IWUSR, sync_max_show, sync_max_store);
+
+static ssize_t
+sync_io_depth_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%d (%s)\n", sync_io_depth(mddev),
+		       mddev->sync_io_depth ? "local" : "system");
+}
+
+static ssize_t
+sync_io_depth_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	unsigned int max;
+	int rv;
+
+	if (strncmp(buf, "system", 6) == 0) {
+		max = 0;
+	} else {
+		rv = kstrtouint(buf, 10, &max);
+		if (rv < 0)
+			return rv;
+		if (max == 0)
+			return -EINVAL;
+	}
+	mddev->sync_io_depth = max;
+	return len;
+}
+
+static struct md_sysfs_entry md_sync_io_depth =
+__ATTR_RW(sync_io_depth);
+
+static ssize_t
+degraded_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%d\n", mddev->degraded);
+}
+static struct md_sysfs_entry md_degraded = __ATTR_RO(degraded);
+
+static ssize_t
+sync_force_parallel_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%d\n", mddev->parallel_resync);
+}
+
+static ssize_t
+sync_force_parallel_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	long n;
+
+	if (kstrtol(buf, 10, &n))
+		return -EINVAL;
+
+	if (n != 0 && n != 1)
+		return -EINVAL;
+
+	mddev->parallel_resync = n;
+
+	if (mddev->sync_thread)
+		wake_up(&resync_wait);
+
+	return len;
+}
+
+/* force parallel resync, even with shared block devices */
+static struct md_sysfs_entry md_sync_force_parallel =
+__ATTR(sync_force_parallel, S_IRUGO|S_IWUSR,
+       sync_force_parallel_show, sync_force_parallel_store);
+
+static ssize_t
+sync_speed_show(struct mddev *mddev, char *page)
+{
+	unsigned long resync, dt, db;
+	if (mddev->curr_resync == MD_RESYNC_NONE)
+		return sprintf(page, "none\n");
+	resync = mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active);
+	dt = (jiffies - mddev->resync_mark) / HZ;
+	if (!dt) dt++;
+	db = resync - mddev->resync_mark_cnt;
+	return sprintf(page, "%lu\n", db/dt/2); /* K/sec */
+}
+
+static struct md_sysfs_entry md_sync_speed = __ATTR_RO(sync_speed);
+
+static ssize_t
+sync_completed_show(struct mddev *mddev, char *page)
+{
+	unsigned long long max_sectors, resync;
+
+	if (!test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+		return sprintf(page, "none\n");
+
+	if (mddev->curr_resync == MD_RESYNC_YIELDED ||
+	    mddev->curr_resync == MD_RESYNC_DELAYED)
+		return sprintf(page, "delayed\n");
+
+	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
+	    test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
+		max_sectors = mddev->resync_max_sectors;
+	else
+		max_sectors = mddev->dev_sectors;
+
+	resync = mddev->curr_resync_completed;
+	return sprintf(page, "%llu / %llu\n", resync, max_sectors);
+}
+
+static struct md_sysfs_entry md_sync_completed =
+	__ATTR_PREALLOC(sync_completed, S_IRUGO, sync_completed_show, NULL);
+
+static ssize_t
+min_sync_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%llu\n",
+		       (unsigned long long)mddev->resync_min);
+}
+static ssize_t
+min_sync_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	unsigned long long min;
+	int err;
+
+	if (kstrtoull(buf, 10, &min))
+		return -EINVAL;
+
+	spin_lock(&mddev->lock);
+	err = -EINVAL;
+	if (min > mddev->resync_max)
+		goto out_unlock;
+
+	err = -EBUSY;
+	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+		goto out_unlock;
+
+	/* Round down to multiple of 4K for safety */
+	mddev->resync_min = round_down(min, 8);
+	err = 0;
+
+out_unlock:
+	spin_unlock(&mddev->lock);
+	return err ?: len;
+}
+
+static struct md_sysfs_entry md_min_sync =
+__ATTR(sync_min, S_IRUGO|S_IWUSR, min_sync_show, min_sync_store);
+
+static ssize_t
+max_sync_show(struct mddev *mddev, char *page)
+{
+	if (mddev->resync_max == MaxSector)
+		return sprintf(page, "max\n");
+	else
+		return sprintf(page, "%llu\n",
+			       (unsigned long long)mddev->resync_max);
+}
+static ssize_t
+max_sync_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	int err;
+	spin_lock(&mddev->lock);
+	if (strncmp(buf, "max", 3) == 0)
+		mddev->resync_max = MaxSector;
+	else {
+		unsigned long long max;
+		int chunk;
+
+		err = -EINVAL;
+		if (kstrtoull(buf, 10, &max))
+			goto out_unlock;
+		if (max < mddev->resync_min)
+			goto out_unlock;
+
+		err = -EBUSY;
+		if (max < mddev->resync_max && md_is_rdwr(mddev) &&
+		    test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+			goto out_unlock;
+
+		/* Must be a multiple of chunk_size */
+		chunk = mddev->chunk_sectors;
+		if (chunk) {
+			sector_t temp = max;
+
+			err = -EINVAL;
+			if (sector_div(temp, chunk))
+				goto out_unlock;
+		}
+		mddev->resync_max = max;
+	}
+	wake_up(&mddev->recovery_wait);
+	err = 0;
+out_unlock:
+	spin_unlock(&mddev->lock);
+	return err ?: len;
+}
+
+static struct md_sysfs_entry md_max_sync =
+__ATTR(sync_max, S_IRUGO|S_IWUSR, max_sync_show, max_sync_store);
+
+static ssize_t
+suspend_lo_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%llu\n",
+		       (unsigned long long)READ_ONCE(mddev->suspend_lo));
+}
+
+static ssize_t
+suspend_lo_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	unsigned long long new;
+	int err;
+
+	err = kstrtoull(buf, 10, &new);
+	if (err < 0)
+		return err;
+	if (new != (sector_t)new)
+		return -EINVAL;
+
+	err = mddev_suspend(mddev, true);
+	if (err)
+		return err;
+
+	WRITE_ONCE(mddev->suspend_lo, new);
+	mddev_resume(mddev);
+
+	return len;
+}
+static struct md_sysfs_entry md_suspend_lo =
+__ATTR(suspend_lo, S_IRUGO|S_IWUSR, suspend_lo_show, suspend_lo_store);
+
+static ssize_t
+suspend_hi_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%llu\n",
+		       (unsigned long long)READ_ONCE(mddev->suspend_hi));
+}
+
+static ssize_t
+suspend_hi_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	unsigned long long new;
+	int err;
+
+	err = kstrtoull(buf, 10, &new);
+	if (err < 0)
+		return err;
+	if (new != (sector_t)new)
+		return -EINVAL;
+
+	err = mddev_suspend(mddev, true);
+	if (err)
+		return err;
+
+	WRITE_ONCE(mddev->suspend_hi, new);
+	mddev_resume(mddev);
+
+	return len;
+}
+static struct md_sysfs_entry md_suspend_hi =
+__ATTR(suspend_hi, S_IRUGO|S_IWUSR, suspend_hi_show, suspend_hi_store);
+
+static ssize_t
+reshape_position_show(struct mddev *mddev, char *page)
+{
+	if (mddev->reshape_position != MaxSector)
+		return sprintf(page, "%llu\n",
+			       (unsigned long long)mddev->reshape_position);
+	strcpy(page, "none\n");
+	return 5;
+}
+
+static ssize_t
+reshape_position_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	struct md_rdev *rdev;
+	unsigned long long new;
+	int err;
+
+	err = kstrtoull(buf, 10, &new);
+	if (err < 0)
+		return err;
+	if (new != (sector_t)new)
+		return -EINVAL;
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	err = -EBUSY;
+	if (mddev->pers)
+		goto unlock;
+	mddev->reshape_position = new;
+	mddev->delta_disks = 0;
+	mddev->reshape_backwards = 0;
+	mddev->new_level = mddev->level;
+	mddev->new_layout = mddev->layout;
+	mddev->new_chunk_sectors = mddev->chunk_sectors;
+	rdev_for_each(rdev, mddev)
+		rdev->new_data_offset = rdev->data_offset;
+	err = 0;
+unlock:
+	mddev_unlock(mddev);
+	return err ?: len;
+}
+
+static struct md_sysfs_entry md_reshape_position =
+__ATTR(reshape_position, S_IRUGO|S_IWUSR, reshape_position_show,
+       reshape_position_store);
+
+static ssize_t
+reshape_direction_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%s\n",
+		       mddev->reshape_backwards ? "backwards" : "forwards");
+}
+
+static ssize_t
+reshape_direction_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	int backwards = 0;
+	int err;
+
+	if (cmd_match(buf, "forwards"))
+		backwards = 0;
+	else if (cmd_match(buf, "backwards"))
+		backwards = 1;
+	else
+		return -EINVAL;
+	if (mddev->reshape_backwards == backwards)
+		return len;
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+	/* check if we are allowed to change */
+	if (mddev->delta_disks)
+		err = -EBUSY;
+	else if (mddev->persistent &&
+	    mddev->major_version == 0)
+		err =  -EINVAL;
+	else
+		mddev->reshape_backwards = backwards;
+	mddev_unlock(mddev);
+	return err ?: len;
+}
+
+static struct md_sysfs_entry md_reshape_direction =
+__ATTR(reshape_direction, S_IRUGO|S_IWUSR, reshape_direction_show,
+       reshape_direction_store);
+
+static ssize_t
+array_size_show(struct mddev *mddev, char *page)
+{
+	if (mddev->external_size)
+		return sprintf(page, "%llu\n",
+			       (unsigned long long)mddev->array_sectors/2);
+	else
+		return sprintf(page, "default\n");
+}
+
+static ssize_t
+array_size_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	sector_t sectors;
+	int err;
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+
+	/* cluster raid doesn't support change array_sectors */
+	if (mddev_is_clustered(mddev)) {
+		mddev_unlock(mddev);
+		return -EINVAL;
+	}
+
+	if (strncmp(buf, "default", 7) == 0) {
+		if (mddev->pers)
+			sectors = mddev->pers->size(mddev, 0, 0);
+		else
+			sectors = mddev->array_sectors;
+
+		mddev->external_size = 0;
+	} else {
+		if (strict_blocks_to_sectors(buf, &sectors) < 0)
+			err = -EINVAL;
+		else if (mddev->pers && mddev->pers->size(mddev, 0, 0) < sectors)
+			err = -E2BIG;
+		else
+			mddev->external_size = 1;
+	}
+
+	if (!err) {
+		mddev->array_sectors = sectors;
+		if (mddev->pers)
+			set_capacity_and_notify(mddev->gendisk,
+						mddev->array_sectors);
+	}
+	mddev_unlock(mddev);
+	return err ?: len;
+}
+
+static struct md_sysfs_entry md_array_size =
+__ATTR(array_size, S_IRUGO|S_IWUSR, array_size_show,
+       array_size_store);
+
+static ssize_t
+consistency_policy_show(struct mddev *mddev, char *page)
+{
+	int ret;
+
+	if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
+		ret = sprintf(page, "journal\n");
+	} else if (test_bit(MD_HAS_PPL, &mddev->flags)) {
+		ret = sprintf(page, "ppl\n");
+	} else if (mddev->bitmap) {
+		ret = sprintf(page, "bitmap\n");
+	} else if (mddev->pers) {
+		if (mddev->pers->sync_request)
+			ret = sprintf(page, "resync\n");
+		else
+			ret = sprintf(page, "none\n");
+	} else {
+		ret = sprintf(page, "unknown\n");
+	}
+
+	return ret;
+}
+
+static ssize_t
+consistency_policy_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	int err = 0;
+
+	if (mddev->pers) {
+		if (mddev->pers->change_consistency_policy)
+			err = mddev->pers->change_consistency_policy(mddev, buf);
+		else
+			err = -EBUSY;
+	} else if (mddev->external && strncmp(buf, "ppl", 3) == 0) {
+		set_bit(MD_HAS_PPL, &mddev->flags);
+	} else {
+		err = -EINVAL;
+	}
+
+	return err ? err : len;
+}
+
+static struct md_sysfs_entry md_consistency_policy =
+__ATTR(consistency_policy, S_IRUGO | S_IWUSR, consistency_policy_show,
+       consistency_policy_store);
+
+static ssize_t fail_last_dev_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%d\n", test_bit(MD_FAILLAST_DEV, &mddev->flags));
+}
+
+/*
+ * Setting MD_FAILLAST_DEV to allow last device to be forcibly removed
+ * from RAID1/RAID10.
+ */
+static ssize_t
+fail_last_dev_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	int ret;
+	bool value;
+
+	ret = kstrtobool(buf, &value);
+	if (ret)
+		return ret;
+
+	if (value)
+		set_bit(MD_FAILLAST_DEV, &mddev->flags);
+	else
+		clear_bit(MD_FAILLAST_DEV, &mddev->flags);
+
+	return len;
+}
+static struct md_sysfs_entry md_fail_last_dev =
+__ATTR(fail_last_dev, S_IRUGO | S_IWUSR, fail_last_dev_show,
+       fail_last_dev_store);
+
+static ssize_t serialize_policy_show(struct mddev *mddev, char *page)
+{
+	if (mddev->pers == NULL || (mddev->pers->head.id != ID_RAID1))
+		return sprintf(page, "n/a\n");
+	else
+		return sprintf(page, "%d\n",
+			       test_bit(MD_SERIALIZE_POLICY, &mddev->flags));
+}
+
+/*
+ * Setting MD_SERIALIZE_POLICY enforce write IO is not reordered
+ * for raid1.
+ */
+static ssize_t
+serialize_policy_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	int err;
+	bool value;
+
+	err = kstrtobool(buf, &value);
+	if (err)
+		return err;
+
+	if (value == test_bit(MD_SERIALIZE_POLICY, &mddev->flags))
+		return len;
+
+	err = mddev_suspend_and_lock(mddev);
+	if (err)
+		return err;
+	if (mddev->pers == NULL || (mddev->pers->head.id != ID_RAID1)) {
+		pr_err("md: serialize_policy is only effective for raid1\n");
+		err = -EINVAL;
+		goto unlock;
+	}
+
+	if (value) {
+		mddev_create_serial_pool(mddev, NULL);
+		set_bit(MD_SERIALIZE_POLICY, &mddev->flags);
+	} else {
+		mddev_destroy_serial_pool(mddev, NULL);
+		clear_bit(MD_SERIALIZE_POLICY, &mddev->flags);
+	}
+unlock:
+	mddev_unlock_and_resume(mddev);
+	return err ?: len;
+}
+
+static struct md_sysfs_entry md_serialize_policy =
+__ATTR(serialize_policy, S_IRUGO | S_IWUSR, serialize_policy_show,
+       serialize_policy_store);
+
+static int mddev_set_logical_block_size(struct mddev *mddev,
+				unsigned int lbs)
+{
+	int err = 0;
+	struct queue_limits lim;
+
+	if (queue_logical_block_size(mddev->gendisk->queue) >= lbs) {
+		pr_err("%s: Cannot set LBS smaller than mddev LBS %u\n",
+		       mdname(mddev), lbs);
+		return -EINVAL;
+	}
+
+	lim = queue_limits_start_update(mddev->gendisk->queue);
+	lim.logical_block_size = lbs;
+	pr_info("%s: logical_block_size is changed, data may be lost\n",
+		mdname(mddev));
+	err = queue_limits_commit_update(mddev->gendisk->queue, &lim);
+	if (err)
+		return err;
+
+	mddev->logical_block_size = lbs;
+	/* New lbs will be written to superblock after array is running */
+	set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
+	return 0;
+}
+
+static ssize_t
+lbs_show(struct mddev *mddev, char *page)
+{
+	return sprintf(page, "%u\n", mddev->logical_block_size);
+}
+
+static ssize_t
+lbs_store(struct mddev *mddev, const char *buf, size_t len)
+{
+	unsigned int lbs;
+	int err = -EBUSY;
+
+	/* Only 1.x meta supports configurable LBS */
+	if (mddev->major_version == 0)
+		return -EINVAL;
+
+	err = kstrtouint(buf, 10, &lbs);
+	if (err < 0)
+		return -EINVAL;
+
+	if (mddev->pers) {
+		unsigned int curr_lbs;
+
+		if (mddev->logical_block_size)
+			return -EBUSY;
+		/*
+		 * To fix forward compatibility issues, LBS is not
+		 * configured for arrays from old kernels (<=6.18) by default.
+		 * If the user confirms no rollback to old kernels,
+		 * enable LBS by writing current LBS — to prevent data
+		 * loss from LBS changes.
+		 */
+		curr_lbs = queue_logical_block_size(mddev->gendisk->queue);
+		if (lbs != curr_lbs)
+			return -EINVAL;
+
+		mddev->logical_block_size = curr_lbs;
+		set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
+		pr_info("%s: logical block size configured successfully, array will not be assembled in old kernels (<= 6.18)\n",
+			mdname(mddev));
+		return len;
+	}
+
+	err = mddev_lock(mddev);
+	if (err)
+		goto unlock;
+
+	err = mddev_set_logical_block_size(mddev, lbs);
+
+unlock:
+	mddev_unlock(mddev);
+	return err ?: len;
+}
+
+static struct md_sysfs_entry md_logical_block_size =
+__ATTR(logical_block_size, 0644, lbs_show, lbs_store);
+
+static struct attribute *md_default_attrs[] = {
+	&md_level.attr,
+	&md_new_level.attr,
+	&md_bitmap_type.attr,
+	&md_layout.attr,
+	&md_raid_disks.attr,
+	&md_uuid.attr,
+	&md_chunk_size.attr,
+	&md_size.attr,
+	&md_resync_start.attr,
+	&md_metadata.attr,
+	&md_new_device.attr,
+	&md_safe_delay.attr,
+	&md_array_state.attr,
+	&md_reshape_position.attr,
+	&md_reshape_direction.attr,
+	&md_array_size.attr,
+	&max_corr_read_errors.attr,
+	&md_consistency_policy.attr,
+	&md_fail_last_dev.attr,
+	&md_serialize_policy.attr,
+	&md_logical_block_size.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(md_default);
+
+static struct attribute *md_redundancy_attrs[] = {
+	&md_scan_mode.attr,
+	&md_last_scan_mode.attr,
+	&md_mismatches.attr,
+	&md_sync_min.attr,
+	&md_sync_max.attr,
+	&md_sync_io_depth.attr,
+	&md_sync_speed.attr,
+	&md_sync_force_parallel.attr,
+	&md_sync_completed.attr,
+	&md_min_sync.attr,
+	&md_max_sync.attr,
+	&md_suspend_lo.attr,
+	&md_suspend_hi.attr,
+	&md_bitmap.attr,
+	&md_degraded.attr,
+	NULL,
+};
+static const struct attribute_group md_redundancy_group = {
+	.name = NULL,
+	.attrs = md_redundancy_attrs,
+};
+
+static ssize_t
+md_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
+{
+	struct md_sysfs_entry *entry = container_of(attr, struct md_sysfs_entry, attr);
+	struct mddev *mddev = container_of(kobj, struct mddev, kobj);
+	ssize_t rv;
+
+	if (!entry->show)
+		return -EIO;
+	spin_lock(&all_mddevs_lock);
+	if (!mddev_get(mddev)) {
+		spin_unlock(&all_mddevs_lock);
+		return -EBUSY;
+	}
+	spin_unlock(&all_mddevs_lock);
+
+	rv = entry->show(mddev, page);
+	mddev_put(mddev);
+	return rv;
+}
+
+static ssize_t
+md_attr_store(struct kobject *kobj, struct attribute *attr,
+	      const char *page, size_t length)
+{
+	struct md_sysfs_entry *entry = container_of(attr, struct md_sysfs_entry, attr);
+	struct mddev *mddev = container_of(kobj, struct mddev, kobj);
+	ssize_t rv;
+	struct kernfs_node *kn = NULL;
+
+	if (!entry->store)
+		return -EIO;
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	if (entry->store == array_state_store && cmd_match(page, "clear"))
+		kn = sysfs_break_active_protection(kobj, attr);
+
+	spin_lock(&all_mddevs_lock);
+	if (!mddev_get(mddev)) {
+		spin_unlock(&all_mddevs_lock);
+		if (kn)
+			sysfs_unbreak_active_protection(kn);
+		return -EBUSY;
+	}
+	spin_unlock(&all_mddevs_lock);
+	rv = entry->store(mddev, page, length);
+
+	/*
+	 * For "array_state=clear", dropping the extra kobject reference from
+	 * sysfs_break_active_protection() can trigger md kobject deletion.
+	 * Restore active protection before mddev_put() so deletion happens
+	 * after the sysfs write path fully unwinds.
+	 */
+	if (kn)
+		sysfs_unbreak_active_protection(kn);
+	mddev_put(mddev);
+
+	return rv;
+}
+
+static void md_kobj_release(struct kobject *ko)
+{
+	struct mddev *mddev = container_of(ko, struct mddev, kobj);
+
+	if (legacy_async_del_gendisk) {
+		if (mddev->sysfs_state)
+			sysfs_put(mddev->sysfs_state);
+		if (mddev->sysfs_level)
+			sysfs_put(mddev->sysfs_level);
+		del_gendisk(mddev->gendisk);
+	}
+	put_disk(mddev->gendisk);
+}
+
+static const struct sysfs_ops md_sysfs_ops = {
+	.show	= md_attr_show,
+	.store	= md_attr_store,
+};
+static const struct kobj_type md_ktype = {
+	.release	= md_kobj_release,
+	.sysfs_ops	= &md_sysfs_ops,
+	.default_groups	= md_default_groups,
+};
+
+int mdp_major = 0;
+
+/* stack the limit for all rdevs into lim */
+int mddev_stack_rdev_limits(struct mddev *mddev, struct queue_limits *lim,
+		unsigned int flags)
+{
+	struct md_rdev *rdev;
+
+	rdev_for_each(rdev, mddev) {
+		queue_limits_stack_bdev(lim, rdev->bdev, rdev->data_offset,
+					mddev->gendisk->disk_name);
+		if ((flags & MDDEV_STACK_INTEGRITY) &&
+		    !queue_limits_stack_integrity_bdev(lim, rdev->bdev))
+			return -EINVAL;
+	}
+
+	/*
+	 * Before RAID adding folio support, the logical_block_size
+	 * should be smaller than the page size.
+	 */
+	if (lim->logical_block_size > PAGE_SIZE) {
+		pr_err("%s: logical_block_size must not larger than PAGE_SIZE\n",
+			mdname(mddev));
+		return -EINVAL;
+	}
+
+	/* Only 1.x meta needs to set logical block size */
+	if (mddev->major_version == 0)
+		return 0;
+
+	/*
+	 * Fix forward compatibility issue. Only set LBS by default for
+	 * new arrays, mddev->events == 0 indicates the array was just
+	 * created. When assembling an array, read LBS from the superblock
+	 * instead — LBS is 0 in superblocks created by old kernels.
+	 */
+	if (!mddev->events) {
+		pr_info("%s: array will not be assembled in old kernels that lack configurable LBS support (<= 6.18)\n",
+			mdname(mddev));
+		mddev->logical_block_size = lim->logical_block_size;
+	}
+
+	if (!mddev->logical_block_size)
+		pr_warn("%s: echo current LBS to md/logical_block_size to prevent data loss issues from LBS changes.\n"
+			"\tNote: After setting, array will not be assembled in old kernels (<= 6.18)\n",
+			mdname(mddev));
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(mddev_stack_rdev_limits);
+
+/* apply the extra stacking limits from a new rdev into mddev */
+int mddev_stack_new_rdev(struct mddev *mddev, struct md_rdev *rdev)
+{
+	struct queue_limits lim;
+
+	if (mddev_is_dm(mddev))
+		return 0;
+
+	if (queue_logical_block_size(rdev->bdev->bd_disk->queue) >
+	    queue_logical_block_size(mddev->gendisk->queue)) {
+		pr_err("%s: incompatible logical_block_size, can not add\n",
+		       mdname(mddev));
+		return -EINVAL;
+	}
+
+	lim = queue_limits_start_update(mddev->gendisk->queue);
+	queue_limits_stack_bdev(&lim, rdev->bdev, rdev->data_offset,
+				mddev->gendisk->disk_name);
+
+	if (!queue_limits_stack_integrity_bdev(&lim, rdev->bdev)) {
+		pr_err("%s: incompatible integrity profile for %pg\n",
+		       mdname(mddev), rdev->bdev);
+		queue_limits_cancel_update(mddev->gendisk->queue);
+		return -ENXIO;
+	}
+
+	return queue_limits_commit_update(mddev->gendisk->queue, &lim);
+}
+EXPORT_SYMBOL_GPL(mddev_stack_new_rdev);
+
+/* update the optimal I/O size after a reshape */
+void mddev_update_io_opt(struct mddev *mddev, unsigned int nr_stripes)
+{
+	struct queue_limits lim;
+
+	if (mddev_is_dm(mddev))
+		return;
+
+	/* don't bother updating io_opt if we can't suspend the array */
+	if (mddev_suspend(mddev, false) < 0)
+		return;
+	lim = queue_limits_start_update(mddev->gendisk->queue);
+	lim.io_opt = lim.io_min * nr_stripes;
+	queue_limits_commit_update(mddev->gendisk->queue, &lim);
+	mddev_resume(mddev);
+}
+EXPORT_SYMBOL_GPL(mddev_update_io_opt);
+
+static void mddev_delayed_delete(struct work_struct *ws)
+{
+	struct mddev *mddev = container_of(ws, struct mddev, del_work);
+
+	kobject_put(&mddev->kobj);
+}
+
+void md_init_stacking_limits(struct queue_limits *lim)
+{
+	blk_set_stacking_limits(lim);
+	lim->features = BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA |
+			BLK_FEAT_IO_STAT;
+}
+EXPORT_SYMBOL_GPL(md_init_stacking_limits);
+
+struct mddev *md_alloc(dev_t dev, char *name)
+{
+	/*
+	 * If dev is zero, name is the name of a device to allocate with
+	 * an arbitrary minor number.  It will be "md_???"
+	 * If dev is non-zero it must be a device number with a MAJOR of
+	 * MD_MAJOR or mdp_major.  In this case, if "name" is NULL, then
+	 * the device is being created by opening a node in /dev.
+	 * If "name" is not NULL, the device is being created by
+	 * writing to /sys/module/md_mod/parameters/new_array.
+	 */
+	static DEFINE_MUTEX(disks_mutex);
+	struct mddev *mddev;
+	struct gendisk *disk;
+	int partitioned;
+	int shift;
+	int unit;
+	int error;
+
+	/*
+	 * Wait for any previous instance of this device to be completely
+	 * removed (mddev_delayed_delete).
+	 */
+	flush_workqueue(md_misc_wq);
+
+	mutex_lock(&disks_mutex);
+	mddev = mddev_alloc(dev);
+	if (IS_ERR(mddev)) {
+		error = PTR_ERR(mddev);
+		goto out_unlock;
+	}
+
+	partitioned = (MAJOR(mddev->unit) != MD_MAJOR);
+	shift = partitioned ? MdpMinorShift : 0;
+	unit = MINOR(mddev->unit) >> shift;
+
+	if (name && !dev) {
+		/* Need to ensure that 'name' is not a duplicate.
+		 */
+		struct mddev *mddev2;
+		spin_lock(&all_mddevs_lock);
+
+		list_for_each_entry(mddev2, &all_mddevs, all_mddevs)
+			if (mddev2->gendisk &&
+			    strcmp(mddev2->gendisk->disk_name, name) == 0) {
+				spin_unlock(&all_mddevs_lock);
+				error = -EEXIST;
+				goto out_free_mddev;
+			}
+		spin_unlock(&all_mddevs_lock);
+	}
+	if (name && dev)
+		/*
+		 * Creating /dev/mdNNN via "newarray", so adjust hold_active.
+		 */
+		mddev->hold_active = UNTIL_STOP;
+
+	disk = blk_alloc_disk(NULL, NUMA_NO_NODE);
+	if (IS_ERR(disk)) {
+		error = PTR_ERR(disk);
+		goto out_free_mddev;
+	}
+
+	disk->major = MAJOR(mddev->unit);
+	disk->first_minor = unit << shift;
+	disk->minors = 1 << shift;
+	if (name)
+		strcpy(disk->disk_name, name);
+	else if (partitioned)
+		sprintf(disk->disk_name, "md_d%d", unit);
+	else
+		sprintf(disk->disk_name, "md%d", unit);
+	disk->fops = &md_fops;
+	disk->private_data = mddev;
+
+	disk->events |= DISK_EVENT_MEDIA_CHANGE;
+	mddev->gendisk = disk;
+	error = add_disk(disk);
+	if (error)
+		goto out_put_disk;
+
+	kobject_init(&mddev->kobj, &md_ktype);
+	error = kobject_add(&mddev->kobj, &disk_to_dev(disk)->kobj, "%s", "md");
+	if (error) {
+		/*
+		 * The disk is already live at this point.  Clear the hold flag
+		 * and let mddev_put take care of the deletion, as it isn't any
+		 * different from a normal close on last release now.
+		 */
+		mddev->hold_active = 0;
+		mutex_unlock(&disks_mutex);
+		mddev_put(mddev);
+		return ERR_PTR(error);
+	}
+
+	kobject_uevent(&mddev->kobj, KOBJ_ADD);
+	mddev->sysfs_state = sysfs_get_dirent_safe(mddev->kobj.sd, "array_state");
+	mddev->sysfs_level = sysfs_get_dirent_safe(mddev->kobj.sd, "level");
+	mutex_unlock(&disks_mutex);
+	return mddev;
+
+out_put_disk:
+	put_disk(disk);
+out_free_mddev:
+	mddev_free(mddev);
+out_unlock:
+	mutex_unlock(&disks_mutex);
+	return ERR_PTR(error);
+}
+
+static int md_alloc_and_put(dev_t dev, char *name)
+{
+	struct mddev *mddev = md_alloc(dev, name);
+
+	if (legacy_async_del_gendisk)
+		pr_warn("md: async del_gendisk mode will be removed in future, please upgrade to mdadm-4.5+\n");
+
+	if (IS_ERR(mddev))
+		return PTR_ERR(mddev);
+	mddev_put(mddev);
+	return 0;
+}
+
+static void md_probe(dev_t dev)
+{
+	if (MAJOR(dev) == MD_MAJOR && MINOR(dev) >= 512)
+		return;
+	if (create_on_open)
+		md_alloc_and_put(dev, NULL);
+}
+
+static int add_named_array(const char *val, const struct kernel_param *kp)
+{
+	/*
+	 * val must be "md_*" or "mdNNN".
+	 * For "md_*" we allocate an array with a large free minor number, and
+	 * set the name to val.  val must not already be an active name.
+	 * For "mdNNN" we allocate an array with the minor number NNN
+	 * which must not already be in use.
+	 */
+	int len = strlen(val);
+	char buf[DISK_NAME_LEN];
+	unsigned long devnum;
+
+	while (len && val[len-1] == '\n')
+		len--;
+	if (len >= DISK_NAME_LEN)
+		return -E2BIG;
+	strscpy(buf, val, len+1);
+	if (strncmp(buf, "md_", 3) == 0)
+		return md_alloc_and_put(0, buf);
+	if (strncmp(buf, "md", 2) == 0 &&
+	    isdigit(buf[2]) &&
+	    kstrtoul(buf+2, 10, &devnum) == 0 &&
+	    devnum <= MINORMASK)
+		return md_alloc_and_put(MKDEV(MD_MAJOR, devnum), NULL);
+
+	return -EINVAL;
+}
+
+static void md_safemode_timeout(struct timer_list *t)
+{
+	struct mddev *mddev = timer_container_of(mddev, t, safemode_timer);
+
+	mddev->safemode = 1;
+	if (mddev->external)
+		sysfs_notify_dirent_safe(mddev->sysfs_state);
+
+	md_wakeup_thread(mddev->thread);
+}
+
+static int start_dirty_degraded;
+
+/*
+ * Read bitmap superblock and return the bitmap_id based on disk version.
+ * This is used as fallback when default bitmap version and on-disk version
+ * doesn't match, and mdadm is not the latest version to set bitmap_type.
+ */
+static enum md_submodule_id md_bitmap_get_id_from_sb(struct mddev *mddev)
+{
+	struct md_rdev *rdev;
+	struct page *sb_page;
+	bitmap_super_t *sb;
+	enum md_submodule_id id = ID_BITMAP_NONE;
+	sector_t sector;
+	u32 version;
+
+	if (!mddev->bitmap_info.offset)
+		return ID_BITMAP_NONE;
+
+	sb_page = alloc_page(GFP_KERNEL);
+	if (!sb_page) {
+		pr_warn("md: %s: failed to allocate memory for bitmap\n",
+			mdname(mddev));
+		return ID_BITMAP_NONE;
+	}
+
+	sector = mddev->bitmap_info.offset;
+
+	rdev_for_each(rdev, mddev) {
+		u32 iosize;
+
+		if (!test_bit(In_sync, &rdev->flags) ||
+		    test_bit(Faulty, &rdev->flags) ||
+		    test_bit(Bitmap_sync, &rdev->flags))
+			continue;
+
+		iosize = roundup(sizeof(bitmap_super_t),
+				 bdev_logical_block_size(rdev->bdev));
+		if (sync_page_io(rdev, sector, iosize, sb_page, REQ_OP_READ,
+				 true))
+			goto read_ok;
+	}
+	pr_warn("md: %s: failed to read bitmap from any device\n",
+		mdname(mddev));
+	goto out;
+
+read_ok:
+	sb = kmap_local_page(sb_page);
+	if (sb->magic != cpu_to_le32(BITMAP_MAGIC)) {
+		pr_warn("md: %s: invalid bitmap magic 0x%x\n",
+			mdname(mddev), le32_to_cpu(sb->magic));
+		goto out_unmap;
+	}
+
+	version = le32_to_cpu(sb->version);
+	switch (version) {
+	case BITMAP_MAJOR_LO:
+	case BITMAP_MAJOR_HI:
+	case BITMAP_MAJOR_CLUSTERED:
+		id = ID_BITMAP;
+		break;
+	case BITMAP_MAJOR_LOCKLESS:
+		id = ID_LLBITMAP;
+		break;
+	default:
+		pr_warn("md: %s: unknown bitmap version %u\n",
+			mdname(mddev), version);
+		break;
+	}
+
+out_unmap:
+	kunmap_local(sb);
+out:
+	__free_page(sb_page);
+	return id;
+}
+
+int md_bitmap_create_nosysfs(struct mddev *mddev)
+{
+	enum md_submodule_id orig_id = mddev->bitmap_id;
+	enum md_submodule_id sb_id;
+	int err;
+
+	if (mddev->bitmap_id == ID_BITMAP_NONE)
+		return -EINVAL;
+
+	if (!mddev_set_bitmap_ops_nosysfs(mddev)) {
+		mddev->bitmap_id = orig_id;
+		return -ENOENT;
+	}
+
+	err = mddev->bitmap_ops->create(mddev);
+	if (!err)
+		return 0;
+
+	/*
+	 * Create failed, if default bitmap version and on-disk version
+	 * doesn't match, and mdadm is not the latest version to set
+	 * bitmap_type, set bitmap_ops based on the disk version.
+	 */
+	mddev->bitmap_ops = NULL;
+
+	sb_id = md_bitmap_get_id_from_sb(mddev);
+	if (sb_id == ID_BITMAP_NONE || sb_id == orig_id) {
+		mddev->bitmap_id = orig_id;
+		return err;
+	}
+
+	pr_info("md: %s: bitmap version mismatch, switching from %d to %d\n",
+		mdname(mddev), orig_id, sb_id);
+
+	mddev->bitmap_id = sb_id;
+	if (!mddev_set_bitmap_ops_nosysfs(mddev)) {
+		mddev->bitmap_id = orig_id;
+		return -ENOENT;
+	}
+
+	err = mddev->bitmap_ops->create(mddev);
+	if (err) {
+		mddev->bitmap_ops = NULL;
+		mddev->bitmap_id = orig_id;
+	}
+
+	return err;
+}
+
+static int md_bitmap_create(struct mddev *mddev)
+{
+	int err;
+
+	err = md_bitmap_create_nosysfs(mddev);
+	if (err)
+		return err;
+
+	if (!mddev_is_dm(mddev) && mddev->bitmap_ops->groups)
+		md_bitmap_sysfs_add(mddev);
+
+	return 0;
+}
+
+void md_bitmap_destroy_nosysfs(struct mddev *mddev)
+{
+	if (!md_bitmap_registered(mddev))
+		return;
+
+	mddev->bitmap_ops->destroy(mddev);
+	mddev->bitmap_ops = NULL;
+}
+
+static void md_bitmap_destroy(struct mddev *mddev)
+{
+	if (!mddev_is_dm(mddev) && mddev->bitmap_ops &&
+	    mddev->bitmap_ops->groups)
+		md_bitmap_sysfs_del(mddev);
+
+	md_bitmap_destroy_nosysfs(mddev);
+}
+
+static void md_bitmap_set_none(struct mddev *mddev)
+{
+	mddev->bitmap_id = ID_BITMAP_NONE;
+	if (!mddev_set_bitmap_ops_nosysfs(mddev))
+		return;
+
+	if (!mddev_is_dm(mddev) && mddev->bitmap_ops->groups)
+		md_bitmap_sysfs_add(mddev);
+}
+
+int md_run(struct mddev *mddev)
+{
+	int err;
+	struct md_rdev *rdev;
+	struct md_personality *pers;
+
+	if (list_empty(&mddev->disks))
+		/* cannot run an array with no devices.. */
+		return -EINVAL;
+
+	if (mddev->pers)
+		return -EBUSY;
+	/* Cannot run until previous stop completes properly */
+	if (mddev->sysfs_active)
+		return -EBUSY;
+
+	/*
+	 * Analyze all RAID superblock(s)
+	 */
+	if (!mddev->raid_disks) {
+		if (!mddev->persistent)
+			return -EINVAL;
+		err = analyze_sbs(mddev);
+		if (err)
+			return -EINVAL;
+	}
+
+	if (mddev->level != LEVEL_NONE)
+		request_module("md-level-%d", mddev->level);
+	else if (mddev->clevel[0])
+		request_module("md-%s", mddev->clevel);
+
+	/*
+	 * Drop all container device buffers, from now on
+	 * the only valid external interface is through the md
+	 * device.
+	 */
+	clear_bit(MD_HAS_SUPERBLOCK, &mddev->flags);
+	rdev_for_each(rdev, mddev) {
+		if (test_bit(Faulty, &rdev->flags))
+			continue;
+		sync_blockdev(rdev->bdev);
+		invalidate_bdev(rdev->bdev);
+		if (mddev->ro != MD_RDONLY && rdev_read_only(rdev)) {
+			mddev->ro = MD_RDONLY;
+			if (!mddev_is_dm(mddev))
+				set_disk_ro(mddev->gendisk, 1);
+		}
+
+		if (rdev->sb_page)
+			set_bit(MD_HAS_SUPERBLOCK, &mddev->flags);
+
+		/* perform some consistency tests on the device.
+		 * We don't want the data to overlap the metadata,
+		 * Internal Bitmap issues have been handled elsewhere.
+		 */
+		if (rdev->meta_bdev) {
+			/* Nothing to check */;
+		} else if (rdev->data_offset < rdev->sb_start) {
+			if (mddev->dev_sectors &&
+			    rdev->data_offset + mddev->dev_sectors
+			    > rdev->sb_start) {
+				pr_warn("md: %s: data overlaps metadata\n",
+					mdname(mddev));
+				return -EINVAL;
+			}
+		} else {
+			if (rdev->sb_start + rdev->sb_size/512
+			    > rdev->data_offset) {
+				pr_warn("md: %s: metadata overlaps data\n",
+					mdname(mddev));
+				return -EINVAL;
+			}
+		}
+		sysfs_notify_dirent_safe(rdev->sysfs_state);
+	}
+
+	pers = get_pers(mddev->level, mddev->clevel);
+	if (!pers)
+		return -EINVAL;
+	if (mddev->level != pers->head.id) {
+		mddev->level = pers->head.id;
+		mddev->new_level = pers->head.id;
+	}
+	strscpy(mddev->clevel, pers->head.name, sizeof(mddev->clevel));
+
+	if (mddev->reshape_position != MaxSector &&
+	    pers->start_reshape == NULL) {
+		/* This personality cannot handle reshaping... */
+		put_pers(pers);
+		return -EINVAL;
+	}
+
+	if (pers->sync_request) {
+		/* Warn if this is a potentially silly
+		 * configuration.
+		 */
+		struct md_rdev *rdev2;
+		int warned = 0;
+
+		rdev_for_each(rdev, mddev)
+			rdev_for_each(rdev2, mddev) {
+				if (rdev < rdev2 &&
+				    rdev->bdev->bd_disk ==
+				    rdev2->bdev->bd_disk) {
+					pr_warn("%s: WARNING: %pg appears to be on the same physical disk as %pg.\n",
+						mdname(mddev),
+						rdev->bdev,
+						rdev2->bdev);
+					warned = 1;
+				}
+			}
+
+		if (warned)
+			pr_warn("True protection against single-disk failure might be compromised.\n");
+	}
+
+	/* dm-raid expect sync_thread to be frozen until resume */
+	if (!mddev_is_dm(mddev))
+		mddev->recovery = 0;
+
+	/* may be over-ridden by personality */
+	mddev->resync_max_sectors = mddev->dev_sectors;
+
+	mddev->ok_start_degraded = start_dirty_degraded;
+
+	if (start_readonly && md_is_rdwr(mddev))
+		mddev->ro = MD_AUTO_READ; /* read-only, but switch on first write */
+
+	err = pers->run(mddev);
+	if (err)
+		pr_warn("md: pers->run() failed ...\n");
+	else if (pers->size(mddev, 0, 0) < mddev->array_sectors) {
+		WARN_ONCE(!mddev->external_size,
+			  "%s: default size too small, but 'external_size' not in effect?\n",
+			  __func__);
+		pr_warn("md: invalid array_size %llu > default size %llu\n",
+			(unsigned long long)mddev->array_sectors / 2,
+			(unsigned long long)pers->size(mddev, 0, 0) / 2);
+		err = -EINVAL;
+	}
+	if (err == 0 && pers->sync_request &&
+	    (mddev->bitmap_info.file || mddev->bitmap_info.offset)) {
+		err = md_bitmap_create(mddev);
+		if (err)
+			pr_warn("%s: failed to create bitmap (%d)\n",
+				mdname(mddev), err);
+	}
+	if (err)
+		goto bitmap_abort;
+
+	if (mddev->bitmap_info.max_write_behind > 0) {
+		bool create_pool = false;
+
+		rdev_for_each(rdev, mddev) {
+			if (test_bit(WriteMostly, &rdev->flags) &&
+			    rdev_init_serial(rdev))
+				create_pool = true;
+		}
+		if (create_pool && mddev->serial_info_pool == NULL) {
+			mddev->serial_info_pool =
+				mempool_create_kmalloc_pool(NR_SERIAL_INFOS,
+						    sizeof(struct serial_info));
+			if (!mddev->serial_info_pool) {
+				err = -ENOMEM;
+				goto bitmap_abort;
+			}
+		}
+	}
+
+	if (pers->sync_request) {
+		if (mddev->kobj.sd &&
+		    sysfs_create_group(&mddev->kobj, &md_redundancy_group))
+			pr_warn("md: cannot register extra attributes for %s\n",
+				mdname(mddev));
+		mddev->sysfs_action = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_action");
+		mddev->sysfs_completed = sysfs_get_dirent_safe(mddev->kobj.sd, "sync_completed");
+		mddev->sysfs_degraded = sysfs_get_dirent_safe(mddev->kobj.sd, "degraded");
+	} else if (mddev->ro == MD_AUTO_READ)
+		mddev->ro = MD_RDWR;
+
+	atomic_set(&mddev->max_corr_read_errors,
+		   MD_DEFAULT_MAX_CORRECTED_READ_ERRORS);
+	mddev->safemode = 0;
+	if (mddev_is_clustered(mddev))
+		mddev->safemode_delay = 0;
+	else
+		mddev->safemode_delay = DEFAULT_SAFEMODE_DELAY;
+	mddev->in_sync = 1;
+	smp_wmb();
+	spin_lock(&mddev->lock);
+	mddev->pers = pers;
+	spin_unlock(&mddev->lock);
+	rdev_for_each(rdev, mddev)
+		if (rdev->raid_disk >= 0)
+			sysfs_link_rdev(mddev, rdev); /* failure here is OK */
+
+	if (mddev->degraded && md_is_rdwr(mddev))
+		/* This ensures that recovering status is reported immediately
+		 * via sysfs - until a lack of spares is confirmed.
+		 */
+		set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
+	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+
+	if (mddev->sb_flags)
+		md_update_sb(mddev, 0);
+
+	if (IS_ENABLED(CONFIG_MD_BITMAP) && !mddev->bitmap_info.file &&
+	    !mddev->bitmap_info.offset)
+		md_bitmap_set_none(mddev);
+
+	md_new_event();
+	return 0;
+
+bitmap_abort:
+	mddev_detach(mddev);
+	if (mddev->private)
+		pers->free(mddev, mddev->private);
+	mddev->private = NULL;
+	put_pers(pers);
+	md_bitmap_destroy(mddev);
+	return err;
+}
+EXPORT_SYMBOL_GPL(md_run);
+
+int do_md_run(struct mddev *mddev)
+{
+	int err;
+
+	set_bit(MD_NOT_READY, &mddev->flags);
+	err = md_run(mddev);
+	if (err)
+		goto out;
+
+	if (md_bitmap_registered(mddev)) {
+		err = mddev->bitmap_ops->load(mddev);
+		if (err) {
+			md_bitmap_destroy(mddev);
+			goto out;
+		}
+	}
+
+	if (mddev_is_clustered(mddev))
+		md_allow_write(mddev);
+
+	/* run start up tasks that require md_thread */
+	md_start(mddev);
+
+	md_wakeup_thread(mddev->sync_thread); /* possibly kick off a reshape */
+
+	set_capacity_and_notify(mddev->gendisk, mddev->array_sectors);
+	clear_bit(MD_NOT_READY, &mddev->flags);
+	mddev->changed = 1;
+	kobject_uevent(&disk_to_dev(mddev->gendisk)->kobj, KOBJ_CHANGE);
+	sysfs_notify_dirent_safe(mddev->sysfs_state);
+	sysfs_notify_dirent_safe(mddev->sysfs_action);
+	sysfs_notify_dirent_safe(mddev->sysfs_degraded);
+out:
+	clear_bit(MD_NOT_READY, &mddev->flags);
+	return err;
+}
+
+int md_start(struct mddev *mddev)
+{
+	int ret = 0;
+
+	if (mddev->pers->start) {
+		set_bit(MD_RECOVERY_WAIT, &mddev->recovery);
+		ret = mddev->pers->start(mddev);
+		clear_bit(MD_RECOVERY_WAIT, &mddev->recovery);
+		md_wakeup_thread(mddev->sync_thread);
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(md_start);
+
+static int restart_array(struct mddev *mddev)
+{
+	struct gendisk *disk = mddev->gendisk;
+	struct md_rdev *rdev;
+	bool has_journal = false;
+	bool has_readonly = false;
+
+	/* Complain if it has no devices */
+	if (list_empty(&mddev->disks))
+		return -ENXIO;
+	if (!mddev->pers)
+		return -EINVAL;
+	if (md_is_rdwr(mddev))
+		return -EBUSY;
+
+	rcu_read_lock();
+	rdev_for_each_rcu(rdev, mddev) {
+		if (test_bit(Journal, &rdev->flags) &&
+		    !test_bit(Faulty, &rdev->flags))
+			has_journal = true;
+		if (rdev_read_only(rdev))
+			has_readonly = true;
+	}
+	rcu_read_unlock();
+	if (test_bit(MD_HAS_JOURNAL, &mddev->flags) && !has_journal)
+		/* Don't restart rw with journal missing/faulty */
+			return -EINVAL;
+	if (has_readonly)
+		return -EROFS;
+
+	mddev->safemode = 0;
+	mddev->ro = MD_RDWR;
+	set_disk_ro(disk, 0);
+	pr_debug("md: %s switched to read-write mode.\n", mdname(mddev));
+	/* Kick recovery or resync if necessary */
+	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	md_wakeup_thread(mddev->sync_thread);
+	sysfs_notify_dirent_safe(mddev->sysfs_state);
+	return 0;
+}
+
+static void md_clean(struct mddev *mddev)
+{
+	mddev->array_sectors = 0;
+	mddev->external_size = 0;
+	mddev->dev_sectors = 0;
+	mddev->raid_disks = 0;
+	mddev->resync_offset = 0;
+	mddev->resync_min = 0;
+	mddev->resync_max = MaxSector;
+	mddev->reshape_position = MaxSector;
+	/* we still need mddev->external in export_rdev, do not clear it yet */
+	mddev->persistent = 0;
+	mddev->level = LEVEL_NONE;
+	mddev->clevel[0] = 0;
+
+	/*
+	 * For legacy_async_del_gendisk mode, it can stop the array in the
+	 * middle of assembling it, then it still can access the array. So
+	 * it needs to clear MD_CLOSING. If not legacy_async_del_gendisk,
+	 * it can't open the array again after stopping it. So it doesn't
+	 * clear MD_CLOSING.
+	 */
+	if (legacy_async_del_gendisk && mddev->hold_active) {
+		clear_bit(MD_CLOSING, &mddev->flags);
+	} else {
+		/* if UNTIL_STOP is set, it's cleared here */
+		mddev->hold_active = 0;
+		/* Don't clear MD_CLOSING, or mddev can be opened again. */
+		mddev->flags &= BIT_ULL_MASK(MD_CLOSING);
+	}
+	mddev->sb_flags = 0;
+	mddev->ro = MD_RDWR;
+	mddev->metadata_type[0] = 0;
+	mddev->chunk_sectors = 0;
+	mddev->ctime = mddev->utime = 0;
+	mddev->layout = 0;
+	mddev->logical_block_size = 0;
+	mddev->max_disks = 0;
+	mddev->events = 0;
+	mddev->can_decrease_events = 0;
+	mddev->delta_disks = 0;
+	mddev->reshape_backwards = 0;
+	mddev->new_level = LEVEL_NONE;
+	mddev->new_layout = 0;
+	mddev->new_chunk_sectors = 0;
+	mddev->curr_resync = MD_RESYNC_NONE;
+	atomic64_set(&mddev->resync_mismatches, 0);
+	mddev->suspend_lo = mddev->suspend_hi = 0;
+	mddev->sync_speed_min = mddev->sync_speed_max = 0;
+	mddev->recovery = 0;
+	mddev->in_sync = 0;
+	mddev->changed = 0;
+	mddev->degraded = 0;
+	mddev->safemode = 0;
+	mddev->private = NULL;
+	mddev->cluster_info = NULL;
+	mddev->bitmap_info.offset = 0;
+	mddev->bitmap_info.default_offset = 0;
+	mddev->bitmap_info.default_space = 0;
+	mddev->bitmap_info.chunksize = 0;
+	mddev->bitmap_info.daemon_sleep = 0;
+	mddev->bitmap_info.max_write_behind = 0;
+	mddev->bitmap_info.nodes = 0;
+}
+
+static void __md_stop_writes(struct mddev *mddev)
+{
+	timer_delete_sync(&mddev->safemode_timer);
+
+	if (md_is_rdwr(mddev) || !mddev_is_dm(mddev)) {
+		if (mddev->pers && mddev->pers->quiesce) {
+			mddev->pers->quiesce(mddev, 1);
+			mddev->pers->quiesce(mddev, 0);
+		}
+
+		if (md_bitmap_enabled(mddev, true))
+			mddev->bitmap_ops->flush(mddev);
+	}
+
+	if (md_is_rdwr(mddev) &&
+	    ((!mddev->in_sync && !mddev_is_clustered(mddev)) ||
+	     mddev->sb_flags)) {
+		/* mark array as shutdown cleanly */
+		if (!mddev_is_clustered(mddev))
+			mddev->in_sync = 1;
+		md_update_sb(mddev, 1);
+	}
+	/* disable policy to guarantee rdevs free resources for serialization */
+	clear_bit(MD_SERIALIZE_POLICY, &mddev->flags);
+	mddev_destroy_serial_pool(mddev, NULL);
+}
+
+void md_stop_writes(struct mddev *mddev)
+{
+	mddev_lock_nointr(mddev);
+	set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+	stop_sync_thread(mddev, true);
+	__md_stop_writes(mddev);
+	mddev_unlock(mddev);
+}
+EXPORT_SYMBOL_GPL(md_stop_writes);
+
+static void mddev_detach(struct mddev *mddev)
+{
+	if (md_bitmap_enabled(mddev, false))
+		mddev->bitmap_ops->wait_behind_writes(mddev);
+	if (mddev->pers && mddev->pers->quiesce && !is_md_suspended(mddev)) {
+		mddev->pers->quiesce(mddev, 1);
+		mddev->pers->quiesce(mddev, 0);
+	}
+	md_unregister_thread(mddev, &mddev->thread);
+
+	/* the unplug fn references 'conf' */
+	if (!mddev_is_dm(mddev))
+		blk_sync_queue(mddev->gendisk->queue);
+}
+
+static void __md_stop(struct mddev *mddev)
+{
+	struct md_personality *pers = mddev->pers;
+
+	mddev_detach(mddev);
+	md_bitmap_destroy(mddev);
+	spin_lock(&mddev->lock);
+	mddev->pers = NULL;
+	spin_unlock(&mddev->lock);
+	if (mddev->private)
+		pers->free(mddev, mddev->private);
+	mddev->private = NULL;
+	put_pers(pers);
+	clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+}
+
+void md_stop(struct mddev *mddev)
+{
+	lockdep_assert_held(&mddev->reconfig_mutex);
+
+	/* stop the array and free an attached data structures.
+	 * This is called from dm-raid
+	 */
+	__md_stop_writes(mddev);
+	__md_stop(mddev);
+}
+
+EXPORT_SYMBOL_GPL(md_stop);
+
+/* ensure 'mddev->pers' exist before calling md_set_readonly() */
+static int md_set_readonly(struct mddev *mddev)
+{
+	int err = 0;
+	int did_freeze = 0;
+
+	if (mddev->external && test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags))
+		return -EBUSY;
+
+	if (!test_bit(MD_RECOVERY_FROZEN, &mddev->recovery)) {
+		did_freeze = 1;
+		set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+	}
+
+	stop_sync_thread(mddev, false);
+	wait_event(mddev->sb_wait,
+		   !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags));
+	mddev_lock_nointr(mddev);
+
+	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) {
+		pr_warn("md: %s still in use.\n",mdname(mddev));
+		err = -EBUSY;
+		goto out;
+	}
+
+	__md_stop_writes(mddev);
+
+	if (mddev->ro == MD_RDONLY) {
+		err  = -ENXIO;
+		goto out;
+	}
+
+	mddev->ro = MD_RDONLY;
+	set_disk_ro(mddev->gendisk, 1);
+
+out:
+	if (!err || did_freeze) {
+		clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+		sysfs_notify_dirent_safe(mddev->sysfs_state);
+	}
+
+	return err;
+}
+
+/* mode:
+ *   0 - completely stop and dis-assemble array
+ *   2 - stop but do not disassemble array
+ */
+static int do_md_stop(struct mddev *mddev, int mode)
+{
+	struct gendisk *disk = mddev->gendisk;
+	struct md_rdev *rdev;
+	int did_freeze = 0;
+
+	if (!test_bit(MD_RECOVERY_FROZEN, &mddev->recovery)) {
+		did_freeze = 1;
+		set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+	}
+
+	stop_sync_thread(mddev, true);
+
+	if (mddev->sysfs_active ||
+	    test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) {
+		pr_warn("md: %s still in use.\n",mdname(mddev));
+		if (did_freeze) {
+			clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+			set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+		}
+		return -EBUSY;
+	}
+	if (mddev->pers) {
+		if (!md_is_rdwr(mddev))
+			set_disk_ro(disk, 0);
+
+		if (mode == 2 && mddev->pers->sync_request &&
+		    mddev->to_remove == NULL)
+			mddev->to_remove = &md_redundancy_group;
+
+		__md_stop_writes(mddev);
+		__md_stop(mddev);
+
+		/* tell userspace to handle 'inactive' */
+		sysfs_notify_dirent_safe(mddev->sysfs_state);
+
+		rdev_for_each(rdev, mddev)
+			if (rdev->raid_disk >= 0)
+				sysfs_unlink_rdev(mddev, rdev);
+
+		set_capacity_and_notify(disk, 0);
+		mddev->changed = 1;
+
+		if (!md_is_rdwr(mddev))
+			mddev->ro = MD_RDWR;
+	}
+	/*
+	 * Free resources if final stop
+	 */
+	if (mode == 0) {
+		pr_info("md: %s stopped.\n", mdname(mddev));
+
+		if (mddev->bitmap_info.file) {
+			struct file *f = mddev->bitmap_info.file;
+			spin_lock(&mddev->lock);
+			mddev->bitmap_info.file = NULL;
+			spin_unlock(&mddev->lock);
+			fput(f);
+		}
+		mddev->bitmap_info.offset = 0;
+
+		export_array(mddev);
+		md_clean(mddev);
+		if (!legacy_async_del_gendisk)
+			set_bit(MD_DELETED, &mddev->flags);
+	}
+	md_new_event();
+	sysfs_notify_dirent_safe(mddev->sysfs_state);
+	return 0;
+}
+
+#ifndef MODULE
+static void autorun_array(struct mddev *mddev)
+{
+	struct md_rdev *rdev;
+	int err;
+
+	if (list_empty(&mddev->disks))
+		return;
+
+	pr_info("md: running: ");
+
+	rdev_for_each(rdev, mddev) {
+		pr_cont("<%pg>", rdev->bdev);
+	}
+	pr_cont("\n");
+
+	err = do_md_run(mddev);
+	if (err) {
+		pr_warn("md: do_md_run() returned %d\n", err);
+		do_md_stop(mddev, 0);
+	}
+}
+
+/*
+ * lets try to run arrays based on all disks that have arrived
+ * until now. (those are in pending_raid_disks)
+ *
+ * the method: pick the first pending disk, collect all disks with
+ * the same UUID, remove all from the pending list and put them into
+ * the 'same_array' list. Then order this list based on superblock
+ * update time (freshest comes first), kick out 'old' disks and
+ * compare superblocks. If everything's fine then run it.
+ *
+ * If "unit" is allocated, then bump its reference count
+ */
+static void autorun_devices(int part)
+{
+	struct md_rdev *rdev0, *rdev, *tmp;
+	struct mddev *mddev;
+
+	pr_info("md: autorun ...\n");
+	while (!list_empty(&pending_raid_disks)) {
+		int unit;
+		dev_t dev;
+		LIST_HEAD(candidates);
+		rdev0 = list_entry(pending_raid_disks.next,
+					 struct md_rdev, same_set);
+
+		pr_debug("md: considering %pg ...\n", rdev0->bdev);
+		INIT_LIST_HEAD(&candidates);
+		rdev_for_each_list(rdev, tmp, &pending_raid_disks)
+			if (super_90_load(rdev, rdev0, 0) >= 0) {
+				pr_debug("md:  adding %pg ...\n",
+					 rdev->bdev);
+				list_move(&rdev->same_set, &candidates);
+			}
+		/*
+		 * now we have a set of devices, with all of them having
+		 * mostly sane superblocks. It's time to allocate the
+		 * mddev.
+		 */
+		if (part) {
+			dev = MKDEV(mdp_major,
+				    rdev0->preferred_minor << MdpMinorShift);
+			unit = MINOR(dev) >> MdpMinorShift;
+		} else {
+			dev = MKDEV(MD_MAJOR, rdev0->preferred_minor);
+			unit = MINOR(dev);
+		}
+		if (rdev0->preferred_minor != unit) {
+			pr_warn("md: unit number in %pg is bad: %d\n",
+				rdev0->bdev, rdev0->preferred_minor);
+			break;
+		}
+
+		mddev = md_alloc(dev, NULL);
+		if (IS_ERR(mddev))
+			break;
+
+		if (mddev_suspend_and_lock(mddev))
+			pr_warn("md: %s locked, cannot run\n", mdname(mddev));
+		else if (mddev->raid_disks || mddev->major_version
+			 || !list_empty(&mddev->disks)) {
+			pr_warn("md: %s already running, cannot run %pg\n",
+				mdname(mddev), rdev0->bdev);
+			mddev_unlock_and_resume(mddev);
+		} else {
+			pr_debug("md: created %s\n", mdname(mddev));
+			mddev->persistent = 1;
+			rdev_for_each_list(rdev, tmp, &candidates) {
+				list_del_init(&rdev->same_set);
+				if (bind_rdev_to_array(rdev, mddev))
+					export_rdev(rdev);
+			}
+			autorun_array(mddev);
+			mddev_unlock_and_resume(mddev);
+		}
+		/* on success, candidates will be empty, on error
+		 * it won't...
+		 */
+		rdev_for_each_list(rdev, tmp, &candidates) {
+			list_del_init(&rdev->same_set);
+			export_rdev(rdev);
+		}
+		mddev_put(mddev);
+	}
+	pr_info("md: ... autorun DONE.\n");
+}
+#endif /* !MODULE */
+
+static int get_version(void __user *arg)
+{
+	mdu_version_t ver;
+
+	ver.major = MD_MAJOR_VERSION;
+	ver.minor = MD_MINOR_VERSION;
+	ver.patchlevel = MD_PATCHLEVEL_VERSION;
+
+	if (copy_to_user(arg, &ver, sizeof(ver)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int get_array_info(struct mddev *mddev, void __user *arg)
+{
+	mdu_array_info_t info;
+	int nr,working,insync,failed,spare;
+	struct md_rdev *rdev;
+
+	nr = working = insync = failed = spare = 0;
+	rcu_read_lock();
+	rdev_for_each_rcu(rdev, mddev) {
+		nr++;
+		if (test_bit(Faulty, &rdev->flags))
+			failed++;
+		else {
+			working++;
+			if (test_bit(In_sync, &rdev->flags))
+				insync++;
+			else if (test_bit(Journal, &rdev->flags))
+				/* TODO: add journal count to md_u.h */
+				;
+			else
+				spare++;
+		}
+	}
+	rcu_read_unlock();
+
+	info.major_version = mddev->major_version;
+	info.minor_version = mddev->minor_version;
+	info.patch_version = MD_PATCHLEVEL_VERSION;
+	info.ctime         = clamp_t(time64_t, mddev->ctime, 0, U32_MAX);
+	info.level         = mddev->level;
+	info.size          = mddev->dev_sectors / 2;
+	if (info.size != mddev->dev_sectors / 2) /* overflow */
+		info.size = -1;
+	info.nr_disks      = nr;
+	info.raid_disks    = mddev->raid_disks;
+	info.md_minor      = mddev->md_minor;
+	info.not_persistent= !mddev->persistent;
+
+	info.utime         = clamp_t(time64_t, mddev->utime, 0, U32_MAX);
+	info.state         = 0;
+	if (mddev->in_sync)
+		info.state = (1<<MD_SB_CLEAN);
+	if (mddev->bitmap && mddev->bitmap_info.offset)
+		info.state |= (1<<MD_SB_BITMAP_PRESENT);
+	if (mddev_is_clustered(mddev))
+		info.state |= (1<<MD_SB_CLUSTERED);
+	info.active_disks  = insync;
+	info.working_disks = working;
+	info.failed_disks  = failed;
+	info.spare_disks   = spare;
+
+	info.layout        = mddev->layout;
+	info.chunk_size    = mddev->chunk_sectors << 9;
+
+	if (copy_to_user(arg, &info, sizeof(info)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static int get_bitmap_file(struct mddev *mddev, void __user * arg)
+{
+	mdu_bitmap_file_t *file = NULL; /* too big for stack allocation */
+	char *ptr;
+	int err;
+
+	file = kzalloc_obj(*file, GFP_NOIO);
+	if (!file)
+		return -ENOMEM;
+
+	err = 0;
+	spin_lock(&mddev->lock);
+	/* bitmap enabled */
+	if (mddev->bitmap_info.file) {
+		ptr = file_path(mddev->bitmap_info.file, file->pathname,
+				sizeof(file->pathname));
+		if (IS_ERR(ptr))
+			err = PTR_ERR(ptr);
+		else
+			memmove(file->pathname, ptr,
+				sizeof(file->pathname)-(ptr-file->pathname));
+	}
+	spin_unlock(&mddev->lock);
+
+	if (err == 0 &&
+	    copy_to_user(arg, file, sizeof(*file)))
+		err = -EFAULT;
+
+	kfree(file);
+	return err;
+}
+
+static int get_disk_info(struct mddev *mddev, void __user * arg)
+{
+	mdu_disk_info_t info;
+	struct md_rdev *rdev;
+
+	if (copy_from_user(&info, arg, sizeof(info)))
+		return -EFAULT;
+
+	rcu_read_lock();
+	rdev = md_find_rdev_nr_rcu(mddev, info.number);
+	if (rdev) {
+		info.major = MAJOR(rdev->bdev->bd_dev);
+		info.minor = MINOR(rdev->bdev->bd_dev);
+		info.raid_disk = rdev->raid_disk;
+		info.state = 0;
+		if (test_bit(Faulty, &rdev->flags))
+			info.state |= (1<<MD_DISK_FAULTY);
+		else if (test_bit(In_sync, &rdev->flags)) {
+			info.state |= (1<<MD_DISK_ACTIVE);
+			info.state |= (1<<MD_DISK_SYNC);
+		}
+		if (test_bit(Journal, &rdev->flags))
+			info.state |= (1<<MD_DISK_JOURNAL);
+		if (test_bit(WriteMostly, &rdev->flags))
+			info.state |= (1<<MD_DISK_WRITEMOSTLY);
+		if (test_bit(FailFast, &rdev->flags))
+			info.state |= (1<<MD_DISK_FAILFAST);
+	} else {
+		info.major = info.minor = 0;
+		info.raid_disk = -1;
+		info.state = (1<<MD_DISK_REMOVED);
+	}
+	rcu_read_unlock();
+
+	if (copy_to_user(arg, &info, sizeof(info)))
+		return -EFAULT;
+
+	return 0;
+}
+
+int md_add_new_disk(struct mddev *mddev, struct mdu_disk_info_s *info)
+{
+	struct md_rdev *rdev;
+	dev_t dev = MKDEV(info->major,info->minor);
+
+	if (mddev_is_clustered(mddev) &&
+		!(info->state & ((1 << MD_DISK_CLUSTER_ADD) | (1 << MD_DISK_CANDIDATE)))) {
+		pr_warn("%s: Cannot add to clustered mddev.\n",
+			mdname(mddev));
+		return -EINVAL;
+	}
+
+	if (info->major != MAJOR(dev) || info->minor != MINOR(dev))
+		return -EOVERFLOW;
+
+	if (!mddev->raid_disks) {
+		int err;
+		/* expecting a device which has a superblock */
+		rdev = md_import_device(dev, mddev->major_version, mddev->minor_version);
+		if (IS_ERR(rdev)) {
+			pr_warn("md: md_import_device returned %ld\n",
+				PTR_ERR(rdev));
+			return PTR_ERR(rdev);
+		}
+		if (!list_empty(&mddev->disks)) {
+			struct md_rdev *rdev0
+				= list_entry(mddev->disks.next,
+					     struct md_rdev, same_set);
+			err = super_types[mddev->major_version]
+				.load_super(rdev, rdev0, mddev->minor_version);
+			if (err < 0) {
+				pr_warn("md: %pg has different UUID to %pg\n",
+					rdev->bdev,
+					rdev0->bdev);
+				export_rdev(rdev);
+				return -EINVAL;
+			}
+		}
+		err = bind_rdev_to_array(rdev, mddev);
+		if (err)
+			export_rdev(rdev);
+		return err;
+	}
+
+	/*
+	 * md_add_new_disk can be used once the array is assembled
+	 * to add "hot spares".  They must already have a superblock
+	 * written
+	 */
+	if (mddev->pers) {
+		int err;
+		if (!mddev->pers->hot_add_disk) {
+			pr_warn("%s: personality does not support diskops!\n",
+				mdname(mddev));
+			return -EINVAL;
+		}
+		if (mddev->persistent)
+			rdev = md_import_device(dev, mddev->major_version,
+						mddev->minor_version);
+		else
+			rdev = md_import_device(dev, -1, -1);
+		if (IS_ERR(rdev)) {
+			pr_warn("md: md_import_device returned %ld\n",
+				PTR_ERR(rdev));
+			return PTR_ERR(rdev);
+		}
+		/* set saved_raid_disk if appropriate */
+		if (!mddev->persistent) {
+			if (info->state & (1<<MD_DISK_SYNC)  &&
+			    info->raid_disk < mddev->raid_disks) {
+				rdev->raid_disk = info->raid_disk;
+				clear_bit(Bitmap_sync, &rdev->flags);
+			} else
+				rdev->raid_disk = -1;
+			rdev->saved_raid_disk = rdev->raid_disk;
+		} else
+			super_types[mddev->major_version].
+				validate_super(mddev, NULL/*freshest*/, rdev);
+		if ((info->state & (1<<MD_DISK_SYNC)) &&
+		     rdev->raid_disk != info->raid_disk) {
+			/* This was a hot-add request, but events doesn't
+			 * match, so reject it.
+			 */
+			export_rdev(rdev);
+			return -EINVAL;
+		}
+
+		clear_bit(In_sync, &rdev->flags); /* just to be sure */
+		if (info->state & (1<<MD_DISK_WRITEMOSTLY))
+			set_bit(WriteMostly, &rdev->flags);
+		else
+			clear_bit(WriteMostly, &rdev->flags);
+		if (info->state & (1<<MD_DISK_FAILFAST))
+			set_bit(FailFast, &rdev->flags);
+		else
+			clear_bit(FailFast, &rdev->flags);
+
+		if (info->state & (1<<MD_DISK_JOURNAL)) {
+			struct md_rdev *rdev2;
+			bool has_journal = false;
+
+			/* make sure no existing journal disk */
+			rdev_for_each(rdev2, mddev) {
+				if (test_bit(Journal, &rdev2->flags)) {
+					has_journal = true;
+					break;
+				}
+			}
+			if (has_journal || mddev->bitmap) {
+				export_rdev(rdev);
+				return -EBUSY;
+			}
+			set_bit(Journal, &rdev->flags);
+		}
+		/*
+		 * check whether the device shows up in other nodes
+		 */
+		if (mddev_is_clustered(mddev)) {
+			if (info->state & (1 << MD_DISK_CANDIDATE))
+				set_bit(Candidate, &rdev->flags);
+			else if (info->state & (1 << MD_DISK_CLUSTER_ADD)) {
+				/* --add initiated by this node */
+				err = mddev->cluster_ops->add_new_disk(mddev, rdev);
+				if (err) {
+					export_rdev(rdev);
+					return err;
+				}
+			}
+		}
+
+		rdev->raid_disk = -1;
+		err = bind_rdev_to_array(rdev, mddev);
+
+		if (err)
+			export_rdev(rdev);
+
+		if (mddev_is_clustered(mddev)) {
+			if (info->state & (1 << MD_DISK_CANDIDATE)) {
+				if (!err) {
+					err = mddev->cluster_ops->new_disk_ack(
+							mddev, err == 0);
+					if (err)
+						md_kick_rdev_from_array(rdev);
+				}
+			} else {
+				if (err)
+					mddev->cluster_ops->add_new_disk_cancel(mddev);
+				else
+					err = add_bound_rdev(rdev);
+			}
+
+		} else if (!err)
+			err = add_bound_rdev(rdev);
+
+		return err;
+	}
+
+	/* otherwise, md_add_new_disk is only allowed
+	 * for major_version==0 superblocks
+	 */
+	if (mddev->major_version != 0) {
+		pr_warn("%s: ADD_NEW_DISK not supported\n", mdname(mddev));
+		return -EINVAL;
+	}
+
+	if (!(info->state & (1<<MD_DISK_FAULTY))) {
+		int err;
+		rdev = md_import_device(dev, -1, 0);
+		if (IS_ERR(rdev)) {
+			pr_warn("md: error, md_import_device() returned %ld\n",
+				PTR_ERR(rdev));
+			return PTR_ERR(rdev);
+		}
+		rdev->desc_nr = info->number;
+		if (info->raid_disk < mddev->raid_disks)
+			rdev->raid_disk = info->raid_disk;
+		else
+			rdev->raid_disk = -1;
+
+		if (rdev->raid_disk < mddev->raid_disks)
+			if (info->state & (1<<MD_DISK_SYNC))
+				set_bit(In_sync, &rdev->flags);
+
+		if (info->state & (1<<MD_DISK_WRITEMOSTLY))
+			set_bit(WriteMostly, &rdev->flags);
+		if (info->state & (1<<MD_DISK_FAILFAST))
+			set_bit(FailFast, &rdev->flags);
+
+		if (!mddev->persistent) {
+			pr_debug("md: nonpersistent superblock ...\n");
+			rdev->sb_start = bdev_nr_sectors(rdev->bdev);
+		} else
+			rdev->sb_start = calc_dev_sboffset(rdev);
+		rdev->sectors = rdev->sb_start;
+
+		err = bind_rdev_to_array(rdev, mddev);
+		if (err) {
+			export_rdev(rdev);
+			return err;
+		}
+	}
+
+	return 0;
+}
+
+static int hot_remove_disk(struct mddev *mddev, dev_t dev)
+{
+	struct md_rdev *rdev;
+
+	if (!mddev->pers)
+		return -ENODEV;
+
+	rdev = find_rdev(mddev, dev);
+	if (!rdev)
+		return -ENXIO;
+
+	if (rdev->raid_disk < 0)
+		goto kick_rdev;
+
+	clear_bit(Blocked, &rdev->flags);
+	remove_and_add_spares(mddev, rdev);
+
+	if (rdev->raid_disk >= 0)
+		goto busy;
+
+kick_rdev:
+	if (mddev_is_clustered(mddev) &&
+	    mddev->cluster_ops->remove_disk(mddev, rdev))
+		goto busy;
+
+	md_kick_rdev_from_array(rdev);
+	set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
+	if (!mddev->thread)
+		md_update_sb(mddev, 1);
+	md_new_event();
+
+	return 0;
+busy:
+	pr_debug("md: cannot remove active disk %pg from %s ...\n",
+		 rdev->bdev, mdname(mddev));
+	return -EBUSY;
+}
+
+static int hot_add_disk(struct mddev *mddev, dev_t dev)
+{
+	int err;
+	struct md_rdev *rdev;
+
+	if (!mddev->pers)
+		return -ENODEV;
+
+	if (mddev->major_version != 0) {
+		pr_warn("%s: HOT_ADD may only be used with version-0 superblocks.\n",
+			mdname(mddev));
+		return -EINVAL;
+	}
+	if (!mddev->pers->hot_add_disk) {
+		pr_warn("%s: personality does not support diskops!\n",
+			mdname(mddev));
+		return -EINVAL;
+	}
+
+	rdev = md_import_device(dev, -1, 0);
+	if (IS_ERR(rdev)) {
+		pr_warn("md: error, md_import_device() returned %ld\n",
+			PTR_ERR(rdev));
+		return -EINVAL;
+	}
+
+	if (mddev->persistent)
+		rdev->sb_start = calc_dev_sboffset(rdev);
+	else
+		rdev->sb_start = bdev_nr_sectors(rdev->bdev);
+
+	rdev->sectors = rdev->sb_start;
+
+	if (test_bit(Faulty, &rdev->flags)) {
+		pr_warn("md: can not hot-add faulty %pg disk to %s!\n",
+			rdev->bdev, mdname(mddev));
+		err = -EINVAL;
+		goto abort_export;
+	}
+
+	clear_bit(In_sync, &rdev->flags);
+	rdev->desc_nr = -1;
+	rdev->saved_raid_disk = -1;
+	err = bind_rdev_to_array(rdev, mddev);
+	if (err)
+		goto abort_export;
+
+	/*
+	 * The rest should better be atomic, we can have disk failures
+	 * noticed in interrupt contexts ...
+	 */
+
+	rdev->raid_disk = -1;
+
+	set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
+	if (!mddev->thread)
+		md_update_sb(mddev, 1);
+	/*
+	 * Kick recovery, maybe this spare has to be added to the
+	 * array immediately.
+	 */
+	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	md_new_event();
+	return 0;
+
+abort_export:
+	export_rdev(rdev);
+	return err;
+}
+
+static int set_bitmap_file(struct mddev *mddev, int fd)
+{
+	int err = 0;
+
+	if (!md_bitmap_registered(mddev) ||
+	    mddev->bitmap_id == ID_BITMAP_NONE)
+		return -EINVAL;
+
+	if (mddev->pers) {
+		if (!mddev->pers->quiesce || !mddev->thread)
+			return -EBUSY;
+		if (mddev->recovery || mddev->sync_thread)
+			return -EBUSY;
+		/* we should be able to change the bitmap.. */
+	}
+
+	if (fd >= 0) {
+		struct inode *inode;
+		struct file *f;
+
+		if (mddev->bitmap || mddev->bitmap_info.file)
+			return -EEXIST; /* cannot add when bitmap is present */
+
+		if (!IS_ENABLED(CONFIG_MD_BITMAP_FILE)) {
+			pr_warn("%s: bitmap files not supported by this kernel\n",
+				mdname(mddev));
+			return -EINVAL;
+		}
+		pr_warn("%s: using deprecated bitmap file support\n",
+			mdname(mddev));
+
+		f = fget(fd);
+
+		if (f == NULL) {
+			pr_warn("%s: error: failed to get bitmap file\n",
+				mdname(mddev));
+			return -EBADF;
+		}
+
+		inode = f->f_mapping->host;
+		if (!S_ISREG(inode->i_mode)) {
+			pr_warn("%s: error: bitmap file must be a regular file\n",
+				mdname(mddev));
+			err = -EBADF;
+		} else if (!(f->f_mode & FMODE_WRITE)) {
+			pr_warn("%s: error: bitmap file must open for write\n",
+				mdname(mddev));
+			err = -EBADF;
+		} else if (atomic_read(&inode->i_writecount) != 1) {
+			pr_warn("%s: error: bitmap file is already in use\n",
+				mdname(mddev));
+			err = -EBUSY;
+		}
+		if (err) {
+			fput(f);
+			return err;
+		}
+		mddev->bitmap_info.file = f;
+		mddev->bitmap_info.offset = 0; /* file overrides offset */
+	} else if (mddev->bitmap == NULL)
+		return -ENOENT; /* cannot remove what isn't there */
+	err = 0;
+	if (mddev->pers) {
+		if (fd >= 0) {
+			err = md_bitmap_create(mddev);
+			if (!err)
+				err = mddev->bitmap_ops->load(mddev);
+
+			if (err) {
+				md_bitmap_destroy(mddev);
+				md_bitmap_set_none(mddev);
+				fd = -1;
+			}
+		} else if (fd < 0) {
+			md_bitmap_destroy(mddev);
+			md_bitmap_set_none(mddev);
+		}
+	}
+
+	if (fd < 0) {
+		struct file *f = mddev->bitmap_info.file;
+		if (f) {
+			spin_lock(&mddev->lock);
+			mddev->bitmap_info.file = NULL;
+			spin_unlock(&mddev->lock);
+			fput(f);
+		}
+	}
+
+	return err;
+}
+
+/*
+ * md_set_array_info is used two different ways
+ * The original usage is when creating a new array.
+ * In this usage, raid_disks is > 0 and it together with
+ *  level, size, not_persistent,layout,chunksize determine the
+ *  shape of the array.
+ *  This will always create an array with a type-0.90.0 superblock.
+ * The newer usage is when assembling an array.
+ *  In this case raid_disks will be 0, and the major_version field is
+ *  use to determine which style super-blocks are to be found on the devices.
+ *  The minor and patch _version numbers are also kept incase the
+ *  super_block handler wishes to interpret them.
+ */
+int md_set_array_info(struct mddev *mddev, struct mdu_array_info_s *info)
+{
+	if (info->raid_disks == 0) {
+		/* just setting version number for superblock loading */
+		if (info->major_version < 0 ||
+		    info->major_version >= ARRAY_SIZE(super_types) ||
+		    super_types[info->major_version].name == NULL) {
+			/* maybe try to auto-load a module? */
+			pr_warn("md: superblock version %d not known\n",
+				info->major_version);
+			return -EINVAL;
+		}
+		mddev->major_version = info->major_version;
+		mddev->minor_version = info->minor_version;
+		mddev->patch_version = info->patch_version;
+		mddev->persistent = !info->not_persistent;
+		/* ensure mddev_put doesn't delete this now that there
+		 * is some minimal configuration.
+		 */
+		mddev->ctime         = ktime_get_real_seconds();
+		return 0;
+	}
+	mddev->major_version = MD_MAJOR_VERSION;
+	mddev->minor_version = MD_MINOR_VERSION;
+	mddev->patch_version = MD_PATCHLEVEL_VERSION;
+	mddev->ctime         = ktime_get_real_seconds();
+
+	mddev->level         = info->level;
+	mddev->clevel[0]     = 0;
+	mddev->dev_sectors   = 2 * (sector_t)info->size;
+	mddev->raid_disks    = info->raid_disks;
+	/* don't set md_minor, it is determined by which /dev/md* was
+	 * openned
+	 */
+	if (info->state & (1<<MD_SB_CLEAN))
+		mddev->resync_offset = MaxSector;
+	else
+		mddev->resync_offset = 0;
+	mddev->persistent    = ! info->not_persistent;
+	mddev->external	     = 0;
+
+	mddev->layout        = info->layout;
+	if (mddev->level == 0)
+		/* Cannot trust RAID0 layout info here */
+		mddev->layout = -1;
+	mddev->chunk_sectors = info->chunk_size >> 9;
+
+	if (mddev->persistent) {
+		mddev->max_disks = MD_SB_DISKS;
+		mddev->flags = 0;
+		mddev->sb_flags = 0;
+	}
+	set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
+
+	mddev->bitmap_info.default_offset = MD_SB_BYTES >> 9;
+	mddev->bitmap_info.default_space = 64*2 - (MD_SB_BYTES >> 9);
+	mddev->bitmap_info.offset = 0;
+
+	mddev->reshape_position = MaxSector;
+
+	/*
+	 * Generate a 128 bit UUID
+	 */
+	get_random_bytes(mddev->uuid, 16);
+
+	mddev->new_level = mddev->level;
+	mddev->new_chunk_sectors = mddev->chunk_sectors;
+	mddev->new_layout = mddev->layout;
+	mddev->delta_disks = 0;
+	mddev->reshape_backwards = 0;
+
+	return 0;
+}
+
+void md_set_array_sectors(struct mddev *mddev, sector_t array_sectors)
+{
+	lockdep_assert_held(&mddev->reconfig_mutex);
+
+	if (mddev->external_size)
+		return;
+
+	mddev->array_sectors = array_sectors;
+}
+EXPORT_SYMBOL(md_set_array_sectors);
+
+static int update_size(struct mddev *mddev, sector_t num_sectors)
+{
+	struct md_rdev *rdev;
+	int rv;
+	int fit = (num_sectors == 0);
+	sector_t old_dev_sectors = mddev->dev_sectors;
+
+	if (mddev->pers->resize == NULL)
+		return -EINVAL;
+	/* The "num_sectors" is the number of sectors of each device that
+	 * is used.  This can only make sense for arrays with redundancy.
+	 * linear and raid0 always use whatever space is available. We can only
+	 * consider changing this number if no resync or reconstruction is
+	 * happening, and if the new size is acceptable. It must fit before the
+	 * sb_start or, if that is <data_offset, it must fit before the size
+	 * of each device.  If num_sectors is zero, we find the largest size
+	 * that fits.
+	 */
+	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+		return -EBUSY;
+	if (!md_is_rdwr(mddev))
+		return -EROFS;
+
+	rdev_for_each(rdev, mddev) {
+		sector_t avail = rdev->sectors;
+
+		if (fit && (num_sectors == 0 || num_sectors > avail))
+			num_sectors = avail;
+		if (avail < num_sectors)
+			return -ENOSPC;
+	}
+	rv = mddev->pers->resize(mddev, num_sectors);
+	if (!rv) {
+		if (mddev_is_clustered(mddev))
+			mddev->cluster_ops->update_size(mddev, old_dev_sectors);
+		else if (!mddev_is_dm(mddev))
+			set_capacity_and_notify(mddev->gendisk,
+						mddev->array_sectors);
+	}
+	return rv;
+}
+
+static int update_raid_disks(struct mddev *mddev, int raid_disks)
+{
+	int rv;
+	struct md_rdev *rdev;
+	/* change the number of raid disks */
+	if (mddev->pers->check_reshape == NULL)
+		return -EINVAL;
+	if (!md_is_rdwr(mddev))
+		return -EROFS;
+	if (raid_disks <= 0 ||
+	    (mddev->max_disks && raid_disks >= mddev->max_disks))
+		return -EINVAL;
+	if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
+	    test_bit(MD_RESYNCING_REMOTE, &mddev->recovery) ||
+	    mddev->reshape_position != MaxSector)
+		return -EBUSY;
+
+	rdev_for_each(rdev, mddev) {
+		if (mddev->raid_disks < raid_disks &&
+		    rdev->data_offset < rdev->new_data_offset)
+			return -EINVAL;
+		if (mddev->raid_disks > raid_disks &&
+		    rdev->data_offset > rdev->new_data_offset)
+			return -EINVAL;
+	}
+
+	mddev->delta_disks = raid_disks - mddev->raid_disks;
+	if (mddev->delta_disks < 0)
+		mddev->reshape_backwards = 1;
+	else if (mddev->delta_disks > 0)
+		mddev->reshape_backwards = 0;
+
+	rv = mddev->pers->check_reshape(mddev);
+	if (rv < 0) {
+		mddev->delta_disks = 0;
+		mddev->reshape_backwards = 0;
+	}
+	return rv;
+}
+
+static int get_cluster_ops(struct mddev *mddev)
+{
+	xa_lock(&md_submodule);
+	mddev->cluster_ops = xa_load(&md_submodule, ID_CLUSTER);
+	if (mddev->cluster_ops &&
+	    !try_module_get(mddev->cluster_ops->head.owner))
+		mddev->cluster_ops = NULL;
+	xa_unlock(&md_submodule);
+
+	return mddev->cluster_ops == NULL ? -ENOENT : 0;
+}
+
+static void put_cluster_ops(struct mddev *mddev)
+{
+	if (!mddev->cluster_ops)
+		return;
+
+	mddev->cluster_ops->leave(mddev);
+	module_put(mddev->cluster_ops->head.owner);
+	mddev->cluster_ops = NULL;
+}
+
+/*
+ * update_array_info is used to change the configuration of an
+ * on-line array.
+ * The version, ctime,level,size,raid_disks,not_persistent, layout,chunk_size
+ * fields in the info are checked against the array.
+ * Any differences that cannot be handled will cause an error.
+ * Normally, only one change can be managed at a time.
+ */
+static int update_array_info(struct mddev *mddev, mdu_array_info_t *info)
+{
+	int rv = 0;
+	int cnt = 0;
+	int state = 0;
+
+	/* calculate expected state,ignoring low bits */
+	if (mddev->bitmap && mddev->bitmap_info.offset)
+		state |= (1 << MD_SB_BITMAP_PRESENT);
+
+	if (mddev->major_version != info->major_version ||
+	    mddev->minor_version != info->minor_version ||
+/*	    mddev->patch_version != info->patch_version || */
+	    mddev->ctime         != info->ctime         ||
+	    mddev->level         != info->level         ||
+/*	    mddev->layout        != info->layout        || */
+	    mddev->persistent	 != !info->not_persistent ||
+	    mddev->chunk_sectors != info->chunk_size >> 9 ||
+	    /* ignore bottom 8 bits of state, and allow SB_BITMAP_PRESENT to change */
+	    ((state^info->state) & 0xfffffe00)
+		)
+		return -EINVAL;
+	/* Check there is only one change */
+	if (info->size >= 0 && mddev->dev_sectors / 2 != info->size)
+		cnt++;
+	if (mddev->raid_disks != info->raid_disks)
+		cnt++;
+	if (mddev->layout != info->layout)
+		cnt++;
+	if ((state ^ info->state) & (1<<MD_SB_BITMAP_PRESENT))
+		cnt++;
+	if (cnt == 0)
+		return 0;
+	if (cnt > 1)
+		return -EINVAL;
+
+	if (mddev->layout != info->layout) {
+		/* Change layout
+		 * we don't need to do anything at the md level, the
+		 * personality will take care of it all.
+		 */
+		if (mddev->pers->check_reshape == NULL)
+			return -EINVAL;
+		else {
+			mddev->new_layout = info->layout;
+			rv = mddev->pers->check_reshape(mddev);
+			if (rv)
+				mddev->new_layout = mddev->layout;
+			return rv;
+		}
+	}
+	if (info->size >= 0 && mddev->dev_sectors / 2 != info->size)
+		rv = update_size(mddev, (sector_t)info->size * 2);
+
+	if (mddev->raid_disks    != info->raid_disks)
+		rv = update_raid_disks(mddev, info->raid_disks);
+
+	if ((state ^ info->state) & (1<<MD_SB_BITMAP_PRESENT)) {
+		if (mddev->pers->quiesce == NULL || mddev->thread == NULL) {
+			rv = -EINVAL;
+			goto err;
+		}
+		if (mddev->recovery || mddev->sync_thread) {
+			rv = -EBUSY;
+			goto err;
+		}
+		if (info->state & (1<<MD_SB_BITMAP_PRESENT)) {
+			/* add the bitmap */
+			if (mddev->bitmap) {
+				rv = -EEXIST;
+				goto err;
+			}
+			if (mddev->bitmap_info.default_offset == 0) {
+				rv = -EINVAL;
+				goto err;
+			}
+			mddev->bitmap_info.offset =
+				mddev->bitmap_info.default_offset;
+			mddev->bitmap_info.space =
+				mddev->bitmap_info.default_space;
+			mddev->bitmap_id = ID_BITMAP;
+			rv = md_bitmap_create(mddev);
+			if (!rv)
+				rv = mddev->bitmap_ops->load(mddev);
+
+			if (rv) {
+				md_bitmap_destroy(mddev);
+				mddev->bitmap_info.offset = 0;
+				md_bitmap_set_none(mddev);
+			}
+		} else {
+			struct md_bitmap_stats stats;
+
+			rv = mddev->bitmap_ops->get_stats(mddev->bitmap, &stats);
+			if (rv)
+				goto err;
+
+			if (stats.file) {
+				rv = -EINVAL;
+				goto err;
+			}
+
+			if (mddev->bitmap_info.nodes) {
+				/* hold PW on all the bitmap lock */
+				if (mddev->cluster_ops->lock_all_bitmaps(mddev) <= 0) {
+					pr_warn("md: can't change bitmap to none since the array is in use by more than one node\n");
+					rv = -EPERM;
+					mddev->cluster_ops->unlock_all_bitmaps(mddev);
+					goto err;
+				}
+
+				mddev->bitmap_info.nodes = 0;
+				put_cluster_ops(mddev);
+				mddev->safemode_delay = DEFAULT_SAFEMODE_DELAY;
+			}
+			md_bitmap_destroy(mddev);
+			mddev->bitmap_info.offset = 0;
+			md_bitmap_set_none(mddev);
+		}
+	}
+	md_update_sb(mddev, 1);
+	return rv;
+err:
+	return rv;
+}
+
+static int set_disk_faulty(struct mddev *mddev, dev_t dev)
+{
+	struct md_rdev *rdev;
+	int err = 0;
+
+	if (mddev->pers == NULL)
+		return -ENODEV;
+
+	rcu_read_lock();
+	rdev = md_find_rdev_rcu(mddev, dev);
+	if (!rdev)
+		err =  -ENODEV;
+	else {
+		md_error(mddev, rdev);
+		if (test_bit(MD_BROKEN, &mddev->flags))
+			err = -EBUSY;
+	}
+	rcu_read_unlock();
+	return err;
+}
+
+/*
+ * We have a problem here : there is no easy way to give a CHS
+ * virtual geometry. We currently pretend that we have a 2 heads
+ * 4 sectors (with a BIG number of cylinders...). This drives
+ * dosfs just mad... ;-)
+ */
+static int md_getgeo(struct gendisk *disk, struct hd_geometry *geo)
+{
+	struct mddev *mddev = disk->private_data;
+
+	geo->heads = 2;
+	geo->sectors = 4;
+	geo->cylinders = mddev->array_sectors / 8;
+	return 0;
+}
+
+static inline int md_ioctl_valid(unsigned int cmd)
+{
+	switch (cmd) {
+	case GET_ARRAY_INFO:
+	case GET_DISK_INFO:
+	case RAID_VERSION:
+		return 0;
+	case ADD_NEW_DISK:
+	case GET_BITMAP_FILE:
+	case HOT_ADD_DISK:
+	case HOT_REMOVE_DISK:
+	case RESTART_ARRAY_RW:
+	case RUN_ARRAY:
+	case SET_ARRAY_INFO:
+	case SET_BITMAP_FILE:
+	case SET_DISK_FAULTY:
+	case STOP_ARRAY:
+	case STOP_ARRAY_RO:
+	case CLUSTERED_DISK_NACK:
+		if (!capable(CAP_SYS_ADMIN))
+			return -EACCES;
+		return 0;
+	default:
+		return -ENOTTY;
+	}
+}
+
+static bool md_ioctl_need_suspend(unsigned int cmd)
+{
+	switch (cmd) {
+	case ADD_NEW_DISK:
+	case HOT_ADD_DISK:
+	case HOT_REMOVE_DISK:
+	case SET_BITMAP_FILE:
+	case SET_ARRAY_INFO:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static int __md_set_array_info(struct mddev *mddev, void __user *argp)
+{
+	mdu_array_info_t info;
+	int err;
+
+	if (!argp)
+		memset(&info, 0, sizeof(info));
+	else if (copy_from_user(&info, argp, sizeof(info)))
+		return -EFAULT;
+
+	if (mddev->pers) {
+		err = update_array_info(mddev, &info);
+		if (err)
+			pr_warn("md: couldn't update array info. %d\n", err);
+		return err;
+	}
+
+	if (!list_empty(&mddev->disks)) {
+		pr_warn("md: array %s already has disks!\n", mdname(mddev));
+		return -EBUSY;
+	}
+
+	if (mddev->raid_disks) {
+		pr_warn("md: array %s already initialised!\n", mdname(mddev));
+		return -EBUSY;
+	}
+
+	err = md_set_array_info(mddev, &info);
+	if (err)
+		pr_warn("md: couldn't set array info. %d\n", err);
+
+	return err;
+}
+
+static int md_ioctl(struct block_device *bdev, blk_mode_t mode,
+			unsigned int cmd, unsigned long arg)
+{
+	int err = 0;
+	unsigned int noio_flags = 0;
+	void __user *argp = (void __user *)arg;
+	struct mddev *mddev = NULL;
+	bool suspend;
+
+	err = md_ioctl_valid(cmd);
+	if (err)
+		return err;
+
+	/*
+	 * Commands dealing with the RAID driver but not any
+	 * particular array:
+	 */
+	if (cmd == RAID_VERSION)
+		return get_version(argp);
+
+	/*
+	 * Commands creating/starting a new array:
+	 */
+
+	mddev = bdev->bd_disk->private_data;
+
+	/* Some actions do not requires the mutex */
+	switch (cmd) {
+	case GET_ARRAY_INFO:
+		if (!mddev->raid_disks && !mddev->external)
+			return -ENODEV;
+		return get_array_info(mddev, argp);
+
+	case GET_DISK_INFO:
+		if (!mddev->raid_disks && !mddev->external)
+			return -ENODEV;
+		return get_disk_info(mddev, argp);
+
+	case SET_DISK_FAULTY:
+		return set_disk_faulty(mddev, new_decode_dev(arg));
+
+	case GET_BITMAP_FILE:
+		return get_bitmap_file(mddev, argp);
+	}
+
+	if (cmd == STOP_ARRAY || cmd == STOP_ARRAY_RO) {
+		/* Need to flush page cache, and ensure no-one else opens
+		 * and writes
+		 */
+		err = mddev_set_closing_and_sync_blockdev(mddev, 1);
+		if (err)
+			return err;
+	}
+
+	if (!md_is_rdwr(mddev))
+		flush_work(&mddev->sync_work);
+
+	suspend = md_ioctl_need_suspend(cmd);
+	err = suspend ? mddev_suspend_and_lock(mddev) : mddev_lock(mddev);
+	if (err) {
+		pr_debug("md: ioctl lock interrupted, reason %d, cmd %d\n",
+			 err, cmd);
+		goto out;
+	}
+	if (suspend)
+		noio_flags = memalloc_noio_save();
+
+	if (cmd == SET_ARRAY_INFO) {
+		err = __md_set_array_info(mddev, argp);
+		goto unlock;
+	}
+
+	/*
+	 * Commands querying/configuring an existing array:
+	 */
+	/* if we are not initialised yet, only ADD_NEW_DISK, STOP_ARRAY,
+	 * RUN_ARRAY, and GET_ and SET_BITMAP_FILE are allowed */
+	if ((!mddev->raid_disks && !mddev->external)
+	    && cmd != ADD_NEW_DISK && cmd != STOP_ARRAY
+	    && cmd != RUN_ARRAY && cmd != SET_BITMAP_FILE
+	    && cmd != GET_BITMAP_FILE) {
+		err = -ENODEV;
+		goto unlock;
+	}
+
+	/*
+	 * Commands even a read-only array can execute:
+	 */
+	switch (cmd) {
+	case RESTART_ARRAY_RW:
+		err = restart_array(mddev);
+		goto unlock;
+
+	case STOP_ARRAY:
+		err = do_md_stop(mddev, 0);
+		goto unlock;
+
+	case STOP_ARRAY_RO:
+		if (mddev->pers)
+			err = md_set_readonly(mddev);
+		goto unlock;
+
+	case HOT_REMOVE_DISK:
+		err = hot_remove_disk(mddev, new_decode_dev(arg));
+		goto unlock;
+
+	case ADD_NEW_DISK:
+		/* We can support ADD_NEW_DISK on read-only arrays
+		 * only if we are re-adding a preexisting device.
+		 * So require mddev->pers and MD_DISK_SYNC.
+		 */
+		if (mddev->pers) {
+			mdu_disk_info_t info;
+			if (copy_from_user(&info, argp, sizeof(info)))
+				err = -EFAULT;
+			else if (!(info.state & (1<<MD_DISK_SYNC)))
+				/* Need to clear read-only for this */
+				break;
+			else
+				err = md_add_new_disk(mddev, &info);
+			goto unlock;
+		}
+		break;
+	}
+
+	/*
+	 * The remaining ioctls are changing the state of the
+	 * superblock, so we do not allow them on read-only arrays.
+	 */
+	if (!md_is_rdwr(mddev) && mddev->pers) {
+		if (mddev->ro != MD_AUTO_READ) {
+			err = -EROFS;
+			goto unlock;
+		}
+		mddev->ro = MD_RDWR;
+		sysfs_notify_dirent_safe(mddev->sysfs_state);
+		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+		/* mddev_unlock will wake thread */
+		/* If a device failed while we were read-only, we
+		 * need to make sure the metadata is updated now.
+		 */
+		if (test_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags)) {
+			mddev_unlock(mddev);
+			wait_event(mddev->sb_wait,
+				   !test_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags) &&
+				   !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags));
+			mddev_lock_nointr(mddev);
+		}
+	}
+
+	switch (cmd) {
+	case ADD_NEW_DISK:
+	{
+		mdu_disk_info_t info;
+		if (copy_from_user(&info, argp, sizeof(info)))
+			err = -EFAULT;
+		else
+			err = md_add_new_disk(mddev, &info);
+		goto unlock;
+	}
+
+	case CLUSTERED_DISK_NACK:
+		if (mddev_is_clustered(mddev))
+			mddev->cluster_ops->new_disk_ack(mddev, false);
+		else
+			err = -EINVAL;
+		goto unlock;
+
+	case HOT_ADD_DISK:
+		err = hot_add_disk(mddev, new_decode_dev(arg));
+		goto unlock;
+
+	case RUN_ARRAY:
+		err = do_md_run(mddev);
+		goto unlock;
+
+	case SET_BITMAP_FILE:
+		err = set_bitmap_file(mddev, (int)arg);
+		goto unlock;
+
+	default:
+		err = -EINVAL;
+		goto unlock;
+	}
+
+unlock:
+	if (mddev->hold_active == UNTIL_IOCTL &&
+	    err != -EINVAL)
+		mddev->hold_active = 0;
+
+	if (suspend) {
+		memalloc_noio_restore(noio_flags);
+		mddev_unlock_and_resume(mddev);
+	} else {
+		mddev_unlock(mddev);
+	}
+
+out:
+	if (cmd == STOP_ARRAY_RO || (err && cmd == STOP_ARRAY))
+		clear_bit(MD_CLOSING, &mddev->flags);
+	return err;
+}
+#ifdef CONFIG_COMPAT
+static int md_compat_ioctl(struct block_device *bdev, blk_mode_t mode,
+		    unsigned int cmd, unsigned long arg)
+{
+	switch (cmd) {
+	case HOT_REMOVE_DISK:
+	case HOT_ADD_DISK:
+	case SET_DISK_FAULTY:
+	case SET_BITMAP_FILE:
+		/* These take in integer arg, do not convert */
+		break;
+	default:
+		arg = (unsigned long)compat_ptr(arg);
+		break;
+	}
+
+	return md_ioctl(bdev, mode, cmd, arg);
+}
+#endif /* CONFIG_COMPAT */
+
+static int md_set_read_only(struct block_device *bdev, bool ro)
+{
+	struct mddev *mddev = bdev->bd_disk->private_data;
+	int err;
+
+	err = mddev_lock(mddev);
+	if (err)
+		return err;
+
+	if (!mddev->raid_disks && !mddev->external) {
+		err = -ENODEV;
+		goto out_unlock;
+	}
+
+	/*
+	 * Transitioning to read-auto need only happen for arrays that call
+	 * md_write_start and which are not ready for writes yet.
+	 */
+	if (!ro && mddev->ro == MD_RDONLY && mddev->pers) {
+		err = restart_array(mddev);
+		if (err)
+			goto out_unlock;
+		mddev->ro = MD_AUTO_READ;
+	}
+
+out_unlock:
+	mddev_unlock(mddev);
+	return err;
+}
+
+static int md_open(struct gendisk *disk, blk_mode_t mode)
+{
+	struct mddev *mddev;
+	int err;
+
+	spin_lock(&all_mddevs_lock);
+	mddev = mddev_get(disk->private_data);
+	spin_unlock(&all_mddevs_lock);
+	if (!mddev)
+		return -ENODEV;
+
+	err = mutex_lock_interruptible(&mddev->open_mutex);
+	if (err)
+		goto out;
+
+	err = -ENODEV;
+	if (test_bit(MD_CLOSING, &mddev->flags))
+		goto out_unlock;
+
+	atomic_inc(&mddev->openers);
+	mutex_unlock(&mddev->open_mutex);
+
+	disk_check_media_change(disk);
+	return 0;
+
+out_unlock:
+	mutex_unlock(&mddev->open_mutex);
+out:
+	mddev_put(mddev);
+	return err;
+}
+
+static void md_release(struct gendisk *disk)
+{
+	struct mddev *mddev = disk->private_data;
+
+	BUG_ON(!mddev);
+	atomic_dec(&mddev->openers);
+	mddev_put(mddev);
+}
+
+static unsigned int md_check_events(struct gendisk *disk, unsigned int clearing)
+{
+	struct mddev *mddev = disk->private_data;
+	unsigned int ret = 0;
+
+	if (mddev->changed)
+		ret = DISK_EVENT_MEDIA_CHANGE;
+	mddev->changed = 0;
+	return ret;
+}
+
+static void md_free_disk(struct gendisk *disk)
+{
+	struct mddev *mddev = disk->private_data;
+
+	mddev_free(mddev);
+}
+
+const struct block_device_operations md_fops =
+{
+	.owner		= THIS_MODULE,
+	.submit_bio	= md_submit_bio,
+	.open		= md_open,
+	.release	= md_release,
+	.ioctl		= md_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= md_compat_ioctl,
+#endif
+	.getgeo		= md_getgeo,
+	.check_events	= md_check_events,
+	.set_read_only	= md_set_read_only,
+	.free_disk	= md_free_disk,
+};
+
+static int md_thread(void *arg)
+{
+	struct md_thread *thread = arg;
+
+	/*
+	 * md_thread is a 'system-thread', it's priority should be very
+	 * high. We avoid resource deadlocks individually in each
+	 * raid personality. (RAID5 does preallocation) We also use RR and
+	 * the very same RT priority as kswapd, thus we will never get
+	 * into a priority inversion deadlock.
+	 *
+	 * we definitely have to have equal or higher priority than
+	 * bdflush, otherwise bdflush will deadlock if there are too
+	 * many dirty RAID5 blocks.
+	 */
+
+	allow_signal(SIGKILL);
+	while (!kthread_should_stop()) {
+
+		/* We need to wait INTERRUPTIBLE so that
+		 * we don't add to the load-average.
+		 * That means we need to be sure no signals are
+		 * pending
+		 */
+		if (signal_pending(current))
+			flush_signals(current);
+
+		wait_event_interruptible_timeout
+			(thread->wqueue,
+			 test_bit(THREAD_WAKEUP, &thread->flags)
+			 || kthread_should_stop() || kthread_should_park(),
+			 thread->timeout);
+
+		clear_bit(THREAD_WAKEUP, &thread->flags);
+		if (kthread_should_park())
+			kthread_parkme();
+		if (!kthread_should_stop())
+			thread->run(thread);
+	}
+
+	return 0;
+}
+
+static void md_wakeup_thread_directly(struct md_thread __rcu **thread)
+{
+	struct md_thread *t;
+
+	rcu_read_lock();
+	t = rcu_dereference(*thread);
+	if (t)
+		wake_up_process(t->tsk);
+	rcu_read_unlock();
+}
+
+void __md_wakeup_thread(struct md_thread __rcu *thread)
+{
+	struct md_thread *t;
+
+	t = rcu_dereference(thread);
+	if (t) {
+		pr_debug("md: waking up MD thread %s.\n", t->tsk->comm);
+		set_bit(THREAD_WAKEUP, &t->flags);
+		if (wq_has_sleeper(&t->wqueue))
+			wake_up(&t->wqueue);
+	}
+}
+EXPORT_SYMBOL(__md_wakeup_thread);
+
+struct md_thread *md_register_thread(void (*run) (struct md_thread *),
+		struct mddev *mddev, const char *name)
+{
+	struct md_thread *thread;
+
+	thread = kzalloc_obj(struct md_thread);
+	if (!thread)
+		return NULL;
+
+	init_waitqueue_head(&thread->wqueue);
+
+	thread->run = run;
+	thread->mddev = mddev;
+	thread->timeout = MAX_SCHEDULE_TIMEOUT;
+	thread->tsk = kthread_run(md_thread, thread,
+				  "%s_%s",
+				  mdname(thread->mddev),
+				  name);
+	if (IS_ERR(thread->tsk)) {
+		kfree(thread);
+		return NULL;
+	}
+	return thread;
+}
+EXPORT_SYMBOL(md_register_thread);
+
+void md_unregister_thread(struct mddev *mddev, struct md_thread __rcu **threadp)
+{
+	struct md_thread *thread = rcu_dereference_protected(*threadp,
+					lockdep_is_held(&mddev->reconfig_mutex));
+
+	if (!thread)
+		return;
+
+	rcu_assign_pointer(*threadp, NULL);
+	synchronize_rcu();
+
+	pr_debug("interrupting MD-thread pid %d\n", task_pid_nr(thread->tsk));
+	kthread_stop(thread->tsk);
+	kfree(thread);
+}
+EXPORT_SYMBOL(md_unregister_thread);
+
+void md_error(struct mddev *mddev, struct md_rdev *rdev)
+{
+	if (!rdev || test_bit(Faulty, &rdev->flags))
+		return;
+
+	if (!mddev->pers || !mddev->pers->error_handler)
+		return;
+	mddev->pers->error_handler(mddev, rdev);
+
+	if (mddev->pers->head.id == ID_RAID0 ||
+	    mddev->pers->head.id == ID_LINEAR)
+		return;
+
+	if (mddev->degraded && !test_bit(MD_BROKEN, &mddev->flags))
+		set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
+	sysfs_notify_dirent_safe(rdev->sysfs_state);
+	set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+	if (!test_bit(MD_BROKEN, &mddev->flags)) {
+		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+		md_wakeup_thread(mddev->thread);
+	}
+	if (mddev->event_work.func)
+		queue_work(md_misc_wq, &mddev->event_work);
+	md_new_event();
+}
+EXPORT_SYMBOL(md_error);
+
+/* seq_file implementation /proc/mdstat */
+
+static void status_unused(struct seq_file *seq)
+{
+	int i = 0;
+	struct md_rdev *rdev;
+
+	seq_printf(seq, "unused devices: ");
+
+	list_for_each_entry(rdev, &pending_raid_disks, same_set) {
+		i++;
+		seq_printf(seq, "%pg ", rdev->bdev);
+	}
+	if (!i)
+		seq_printf(seq, "<none>");
+
+	seq_printf(seq, "\n");
+}
+
+static void status_personalities(struct seq_file *seq)
+{
+	struct md_submodule_head *head;
+	unsigned long i;
+
+	seq_puts(seq, "Personalities : ");
+
+	xa_lock(&md_submodule);
+	xa_for_each(&md_submodule, i, head)
+		if (head->type == MD_PERSONALITY)
+			seq_printf(seq, "[%s] ", head->name);
+	xa_unlock(&md_submodule);
+
+	seq_puts(seq, "\n");
+}
+
+static int status_resync(struct seq_file *seq, struct mddev *mddev)
+{
+	sector_t max_sectors, resync, res;
+	unsigned long dt, db = 0;
+	sector_t rt, curr_mark_cnt, resync_mark_cnt;
+	int scale, recovery_active;
+	unsigned int per_milli;
+
+	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
+	    test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
+		max_sectors = mddev->resync_max_sectors;
+	else
+		max_sectors = mddev->dev_sectors;
+
+	resync = mddev->curr_resync;
+	if (resync < MD_RESYNC_ACTIVE) {
+		if (test_bit(MD_RECOVERY_DONE, &mddev->recovery))
+			/* Still cleaning up */
+			resync = max_sectors;
+	} else if (resync > max_sectors) {
+		resync = max_sectors;
+	} else {
+		res = atomic_read(&mddev->recovery_active);
+		/*
+		 * Resync has started, but the subtraction has overflowed or
+		 * yielded one of the special values. Force it to active to
+		 * ensure the status reports an active resync.
+		 */
+		if (resync < res || resync - res < MD_RESYNC_ACTIVE)
+			resync = MD_RESYNC_ACTIVE;
+		else
+			resync -= res;
+	}
+
+	if (resync == MD_RESYNC_NONE) {
+		if (test_bit(MD_RESYNCING_REMOTE, &mddev->recovery)) {
+			struct md_rdev *rdev;
+
+			rdev_for_each(rdev, mddev)
+				if (rdev->raid_disk >= 0 &&
+				    !test_bit(Faulty, &rdev->flags) &&
+				    rdev->recovery_offset != MaxSector &&
+				    rdev->recovery_offset) {
+					seq_printf(seq, "\trecover=REMOTE");
+					return 1;
+				}
+			if (mddev->reshape_position != MaxSector)
+				seq_printf(seq, "\treshape=REMOTE");
+			else
+				seq_printf(seq, "\tresync=REMOTE");
+			return 1;
+		}
+		if (mddev->resync_offset < MaxSector) {
+			seq_printf(seq, "\tresync=PENDING");
+			return 1;
+		}
+		return 0;
+	}
+	if (resync < MD_RESYNC_ACTIVE) {
+		seq_printf(seq, "\tresync=DELAYED");
+		return 1;
+	}
+
+	WARN_ON(max_sectors == 0);
+	/* Pick 'scale' such that (resync>>scale)*1000 will fit
+	 * in a sector_t, and (max_sectors>>scale) will fit in a
+	 * u32, as those are the requirements for sector_div.
+	 * Thus 'scale' must be at least 10
+	 */
+	scale = 10;
+	if (sizeof(sector_t) > sizeof(unsigned long)) {
+		while ( max_sectors/2 > (1ULL<<(scale+32)))
+			scale++;
+	}
+	res = (resync>>scale)*1000;
+	sector_div(res, (u32)((max_sectors>>scale)+1));
+
+	per_milli = res;
+	{
+		int i, x = per_milli/50, y = 20-x;
+		seq_printf(seq, "[");
+		for (i = 0; i < x; i++)
+			seq_printf(seq, "=");
+		seq_printf(seq, ">");
+		for (i = 0; i < y; i++)
+			seq_printf(seq, ".");
+		seq_printf(seq, "] ");
+	}
+	seq_printf(seq, " %s =%3u.%u%% (%llu/%llu)",
+		   (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)?
+		    "reshape" :
+		    (test_bit(MD_RECOVERY_CHECK, &mddev->recovery)?
+		     "check" :
+		     (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ?
+		      "resync" : "recovery"))),
+		   per_milli/10, per_milli % 10,
+		   (unsigned long long) resync/2,
+		   (unsigned long long) max_sectors/2);
+
+	/*
+	 * dt: time from mark until now
+	 * db: blocks written from mark until now
+	 * rt: remaining time
+	 *
+	 * rt is a sector_t, which is always 64bit now. We are keeping
+	 * the original algorithm, but it is not really necessary.
+	 *
+	 * Original algorithm:
+	 *   So we divide before multiply in case it is 32bit and close
+	 *   to the limit.
+	 *   We scale the divisor (db) by 32 to avoid losing precision
+	 *   near the end of resync when the number of remaining sectors
+	 *   is close to 'db'.
+	 *   We then divide rt by 32 after multiplying by db to compensate.
+	 *   The '+1' avoids division by zero if db is very small.
+	 */
+	dt = ((jiffies - mddev->resync_mark) / HZ);
+	if (!dt) dt++;
+
+	curr_mark_cnt = mddev->curr_mark_cnt;
+	recovery_active = atomic_read(&mddev->recovery_active);
+	resync_mark_cnt = mddev->resync_mark_cnt;
+
+	if (curr_mark_cnt >= (recovery_active + resync_mark_cnt))
+		db = curr_mark_cnt - (recovery_active + resync_mark_cnt);
+
+	rt = max_sectors - resync;    /* number of remaining sectors */
+	rt = div64_u64(rt, db/32+1);
+	rt *= dt;
+	rt >>= 5;
+
+	seq_printf(seq, " finish=%lu.%lumin", (unsigned long)rt / 60,
+		   ((unsigned long)rt % 60)/6);
+
+	seq_printf(seq, " speed=%ldK/sec", db/2/dt);
+	return 1;
+}
+
+static void *md_seq_start(struct seq_file *seq, loff_t *pos)
+	__acquires(&all_mddevs_lock)
+{
+	seq->poll_event = atomic_read(&md_event_count);
+	spin_lock(&all_mddevs_lock);
+
+	return seq_list_start_head(&all_mddevs, *pos);
+}
+
+static void *md_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	return seq_list_next(v, &all_mddevs, pos);
+}
+
+static void md_seq_stop(struct seq_file *seq, void *v)
+	__releases(&all_mddevs_lock)
+{
+	spin_unlock(&all_mddevs_lock);
+}
+
+static void md_bitmap_status(struct seq_file *seq, struct mddev *mddev)
+{
+	struct md_bitmap_stats stats;
+	unsigned long used_pages;
+	unsigned long chunk_kb;
+	int err;
+
+	if (!md_bitmap_enabled(mddev, false))
+		return;
+
+	err = mddev->bitmap_ops->get_stats(mddev->bitmap, &stats);
+	if (err)
+		return;
+
+	chunk_kb = mddev->bitmap_info.chunksize >> 10;
+	used_pages = stats.pages - stats.missing_pages;
+
+	seq_printf(seq, "bitmap: %lu/%lu pages [%luKB], %lu%s chunk",
+		   used_pages, stats.pages, used_pages << (PAGE_SHIFT - 10),
+		   chunk_kb ? chunk_kb : mddev->bitmap_info.chunksize,
+		   chunk_kb ? "KB" : "B");
+
+	if (stats.file) {
+		seq_puts(seq, ", file: ");
+		seq_file_path(seq, stats.file, " \t\n");
+	}
+
+	seq_putc(seq, '\n');
+}
+
+static int md_seq_show(struct seq_file *seq, void *v)
+{
+	struct mddev *mddev;
+	sector_t sectors;
+	struct md_rdev *rdev;
+
+	if (v == &all_mddevs) {
+		status_personalities(seq);
+		if (list_empty(&all_mddevs))
+			status_unused(seq);
+		return 0;
+	}
+
+	mddev = list_entry(v, struct mddev, all_mddevs);
+	if (!mddev_get(mddev))
+		return 0;
+
+	spin_unlock(&all_mddevs_lock);
+
+	/* prevent bitmap to be freed after checking */
+	mutex_lock(&mddev->bitmap_info.mutex);
+
+	spin_lock(&mddev->lock);
+	if (mddev->pers || mddev->raid_disks || !list_empty(&mddev->disks)) {
+		seq_printf(seq, "%s : ", mdname(mddev));
+		if (mddev->pers) {
+			if (test_bit(MD_BROKEN, &mddev->flags))
+				seq_printf(seq, "broken");
+			else
+				seq_printf(seq, "active");
+			if (mddev->ro == MD_RDONLY)
+				seq_printf(seq, " (read-only)");
+			if (mddev->ro == MD_AUTO_READ)
+				seq_printf(seq, " (auto-read-only)");
+			seq_printf(seq, " %s", mddev->pers->head.name);
+		} else {
+			seq_printf(seq, "inactive");
+		}
+
+		sectors = 0;
+		rcu_read_lock();
+		rdev_for_each_rcu(rdev, mddev) {
+			seq_printf(seq, " %pg[%d]", rdev->bdev, rdev->desc_nr);
+
+			if (test_bit(WriteMostly, &rdev->flags))
+				seq_printf(seq, "(W)");
+			if (test_bit(Journal, &rdev->flags))
+				seq_printf(seq, "(J)");
+			if (test_bit(Faulty, &rdev->flags)) {
+				seq_printf(seq, "(F)");
+				continue;
+			}
+			if (rdev->raid_disk < 0)
+				seq_printf(seq, "(S)"); /* spare */
+			if (test_bit(Replacement, &rdev->flags))
+				seq_printf(seq, "(R)");
+			sectors += rdev->sectors;
+		}
+		rcu_read_unlock();
+
+		if (!list_empty(&mddev->disks)) {
+			if (mddev->pers)
+				seq_printf(seq, "\n      %llu blocks",
+					   (unsigned long long)
+					   mddev->array_sectors / 2);
+			else
+				seq_printf(seq, "\n      %llu blocks",
+					   (unsigned long long)sectors / 2);
+		}
+		if (mddev->persistent) {
+			if (mddev->major_version != 0 ||
+			    mddev->minor_version != 90) {
+				seq_printf(seq," super %d.%d",
+					   mddev->major_version,
+					   mddev->minor_version);
+			}
+		} else if (mddev->external)
+			seq_printf(seq, " super external:%s",
+				   mddev->metadata_type);
+		else
+			seq_printf(seq, " super non-persistent");
+
+		if (mddev->pers) {
+			mddev->pers->status(seq, mddev);
+			seq_printf(seq, "\n      ");
+			if (mddev->pers->sync_request) {
+				if (status_resync(seq, mddev))
+					seq_printf(seq, "\n      ");
+			}
+		} else
+			seq_printf(seq, "\n       ");
+
+		md_bitmap_status(seq, mddev);
+
+		seq_printf(seq, "\n");
+	}
+	spin_unlock(&mddev->lock);
+	mutex_unlock(&mddev->bitmap_info.mutex);
+	spin_lock(&all_mddevs_lock);
+
+	if (mddev == list_last_entry(&all_mddevs, struct mddev, all_mddevs))
+		status_unused(seq);
+
+	mddev_put_locked(mddev);
+	return 0;
+}
+
+static const struct seq_operations md_seq_ops = {
+	.start  = md_seq_start,
+	.next   = md_seq_next,
+	.stop   = md_seq_stop,
+	.show   = md_seq_show,
+};
+
+static int md_seq_open(struct inode *inode, struct file *file)
+{
+	struct seq_file *seq;
+	int error;
+
+	error = seq_open(file, &md_seq_ops);
+	if (error)
+		return error;
+
+	seq = file->private_data;
+	seq->poll_event = atomic_read(&md_event_count);
+	return error;
+}
+
+static int md_unloading;
+static __poll_t mdstat_poll(struct file *filp, poll_table *wait)
+{
+	struct seq_file *seq = filp->private_data;
+	__poll_t mask;
+
+	if (md_unloading)
+		return EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI;
+	poll_wait(filp, &md_event_waiters, wait);
+
+	/* always allow read */
+	mask = EPOLLIN | EPOLLRDNORM;
+
+	if (seq->poll_event != atomic_read(&md_event_count))
+		mask |= EPOLLERR | EPOLLPRI;
+	return mask;
+}
+
+static const struct proc_ops mdstat_proc_ops = {
+	.proc_open	= md_seq_open,
+	.proc_read	= seq_read,
+	.proc_lseek	= seq_lseek,
+	.proc_release	= seq_release,
+	.proc_poll	= mdstat_poll,
+};
+
+int register_md_submodule(struct md_submodule_head *msh)
+{
+	return xa_insert(&md_submodule, msh->id, msh, GFP_KERNEL);
+}
+EXPORT_SYMBOL_GPL(register_md_submodule);
+
+void unregister_md_submodule(struct md_submodule_head *msh)
+{
+	xa_erase(&md_submodule, msh->id);
+}
+EXPORT_SYMBOL_GPL(unregister_md_submodule);
+
+int md_setup_cluster(struct mddev *mddev, int nodes)
+{
+	int ret = get_cluster_ops(mddev);
+
+	if (ret) {
+		request_module("md-cluster");
+		ret = get_cluster_ops(mddev);
+	}
+
+	/* ensure module won't be unloaded */
+	if (ret) {
+		pr_warn("can't find md-cluster module or get its reference.\n");
+		return ret;
+	}
+
+	ret = mddev->cluster_ops->join(mddev, nodes);
+	if (!ret)
+		mddev->safemode_delay = 0;
+	return ret;
+}
+
+void md_cluster_stop(struct mddev *mddev)
+{
+	put_cluster_ops(mddev);
+}
+
+static bool is_rdev_holder_idle(struct md_rdev *rdev, bool init)
+{
+	unsigned long last_events = rdev->last_events;
+
+	if (!bdev_is_partition(rdev->bdev))
+		return true;
+
+	/*
+	 * If rdev is partition, and user doesn't issue IO to the array, the
+	 * array is still not idle if user issues IO to other partitions.
+	 */
+	rdev->last_events = part_stat_read_accum(rdev->bdev->bd_disk->part0,
+						 sectors) -
+			    part_stat_read_accum(rdev->bdev, sectors);
+
+	return init || rdev->last_events <= last_events;
+}
+
+/*
+ * mddev is idle if following conditions are matched since last check:
+ * 1) mddev doesn't have normal IO completed;
+ * 2) mddev doesn't have inflight normal IO;
+ * 3) if any member disk is partition, and other partitions don't have IO
+ *    completed;
+ *
+ * Noted this checking rely on IO accounting is enabled.
+ */
+static bool is_mddev_idle(struct mddev *mddev, int init)
+{
+	unsigned long last_events = mddev->normal_io_events;
+	struct gendisk *disk;
+	struct md_rdev *rdev;
+	bool idle = true;
+
+	disk = mddev_is_dm(mddev) ? mddev->dm_gendisk : mddev->gendisk;
+	if (!disk)
+		return true;
+
+	mddev->normal_io_events = part_stat_read_accum(disk->part0, sectors);
+	if (!init && (mddev->normal_io_events > last_events ||
+		      bdev_count_inflight(disk->part0)))
+		idle = false;
+
+	rcu_read_lock();
+	rdev_for_each_rcu(rdev, mddev)
+		if (!is_rdev_holder_idle(rdev, init))
+			idle = false;
+	rcu_read_unlock();
+
+	return idle;
+}
+
+void md_done_sync(struct mddev *mddev, int blocks)
+{
+	/* another "blocks" (512byte) blocks have been synced */
+	atomic_sub(blocks, &mddev->recovery_active);
+	wake_up(&mddev->recovery_wait);
+}
+EXPORT_SYMBOL(md_done_sync);
+
+void md_sync_error(struct mddev *mddev)
+{
+	// stop recovery, signal do_sync ....
+	set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+	md_wakeup_thread(mddev->thread);
+}
+EXPORT_SYMBOL(md_sync_error);
+
+/* md_write_start(mddev, bi)
+ * If we need to update some array metadata (e.g. 'active' flag
+ * in superblock) before writing, schedule a superblock update
+ * and wait for it to complete.
+ * A return value of 'false' means that the write wasn't recorded
+ * and cannot proceed as the array is being suspend.
+ */
+void md_write_start(struct mddev *mddev, struct bio *bi)
+{
+	int did_change = 0;
+
+	if (bio_data_dir(bi) != WRITE)
+		return;
+
+	BUG_ON(mddev->ro == MD_RDONLY);
+	if (mddev->ro == MD_AUTO_READ) {
+		/* need to switch to read/write */
+		mddev->ro = MD_RDWR;
+		set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+		md_wakeup_thread(mddev->thread);
+		md_wakeup_thread(mddev->sync_thread);
+		did_change = 1;
+	}
+	rcu_read_lock();
+	percpu_ref_get(&mddev->writes_pending);
+	smp_mb(); /* Match smp_mb in set_in_sync() */
+	if (mddev->safemode == 1)
+		mddev->safemode = 0;
+	/* sync_checkers is always 0 when writes_pending is in per-cpu mode */
+	if (mddev->in_sync || mddev->sync_checkers) {
+		spin_lock(&mddev->lock);
+		if (mddev->in_sync) {
+			mddev->in_sync = 0;
+			set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
+			set_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
+			md_wakeup_thread(mddev->thread);
+			did_change = 1;
+		}
+		spin_unlock(&mddev->lock);
+	}
+	rcu_read_unlock();
+	if (did_change)
+		sysfs_notify_dirent_safe(mddev->sysfs_state);
+	if (!test_bit(MD_HAS_SUPERBLOCK, &mddev->flags))
+		return;
+	wait_event(mddev->sb_wait,
+		   !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags));
+}
+EXPORT_SYMBOL(md_write_start);
+
+/* md_write_inc can only be called when md_write_start() has
+ * already been called at least once of the current request.
+ * It increments the counter and is useful when a single request
+ * is split into several parts.  Each part causes an increment and
+ * so needs a matching md_write_end().
+ * Unlike md_write_start(), it is safe to call md_write_inc() inside
+ * a spinlocked region.
+ */
+void md_write_inc(struct mddev *mddev, struct bio *bi)
+{
+	if (bio_data_dir(bi) != WRITE)
+		return;
+	WARN_ON_ONCE(mddev->in_sync || !md_is_rdwr(mddev));
+	percpu_ref_get(&mddev->writes_pending);
+}
+EXPORT_SYMBOL(md_write_inc);
+
+void md_write_end(struct mddev *mddev)
+{
+	percpu_ref_put(&mddev->writes_pending);
+
+	if (mddev->safemode == 2)
+		md_wakeup_thread(mddev->thread);
+	else if (mddev->safemode_delay)
+		/* The roundup() ensures this only performs locking once
+		 * every ->safemode_delay jiffies
+		 */
+		mod_timer(&mddev->safemode_timer,
+			  roundup(jiffies, mddev->safemode_delay) +
+			  mddev->safemode_delay);
+}
+
+EXPORT_SYMBOL(md_write_end);
+
+/* This is used by raid0 and raid10 */
+void md_submit_discard_bio(struct mddev *mddev, struct md_rdev *rdev,
+			struct bio *bio, sector_t start, sector_t size)
+{
+	struct bio *discard_bio = NULL;
+
+	/* Discard is optional, so silently skip members that do not support it. */
+	if (unlikely(!bdev_max_discard_sectors(rdev->bdev)))
+		return;
+
+	__blkdev_issue_discard(rdev->bdev, start, size, GFP_NOIO, &discard_bio);
+	if (!discard_bio)
+		return;
+
+	bio_chain(discard_bio, bio);
+	bio_clone_blkg_association(discard_bio, bio);
+	mddev_trace_remap(mddev, discard_bio, bio->bi_iter.bi_sector);
+	submit_bio_noacct(discard_bio);
+}
+EXPORT_SYMBOL_GPL(md_submit_discard_bio);
+
+struct bio *mddev_bio_split_at_reshape_offset(struct mddev *mddev,
+					      struct bio *bio,
+					      unsigned int *max_sectors,
+					      struct bio_set *bs)
+{
+	sector_t boundary;
+	sector_t start;
+	sector_t end;
+	unsigned int split_sectors;
+
+	split_sectors = bio_sectors(bio);
+	if (max_sectors && *max_sectors && *max_sectors < split_sectors)
+		split_sectors = *max_sectors;
+
+	if (!test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
+		goto split;
+
+	boundary = READ_ONCE(mddev->reshape_position);
+	start = bio->bi_iter.bi_sector;
+	end = bio_end_sector(bio);
+	if (start >= boundary || end <= boundary)
+		goto split;
+
+	if (boundary - start < split_sectors)
+		split_sectors = boundary - start;
+
+split:
+	if (max_sectors)
+		*max_sectors = split_sectors;
+	if (split_sectors < bio_sectors(bio)) {
+		bio = bio_submit_split_bioset(bio, split_sectors, bs);
+		if (bio)
+			bio->bi_opf |= REQ_NOMERGE;
+	}
+
+	return bio;
+}
+EXPORT_SYMBOL_GPL(mddev_bio_split_at_reshape_offset);
+
+static void md_bitmap_prepare_range(struct mddev *mddev, sector_t *offset,
+				    unsigned long *sectors, bool discard)
+{
+	mddev->bitmap_ops->prepare_range(mddev, offset, sectors, discard);
+}
+
+static void md_bitmap_start(struct mddev *mddev,
+			    struct md_io_clone *md_io_clone)
+{
+	bool discard = md_io_clone->rw == STAT_DISCARD;
+	md_bitmap_fn *fn = discard ? mddev->bitmap_ops->start_discard :
+			   mddev->bitmap_ops->start_write;
+
+	md_bitmap_prepare_range(mddev, &md_io_clone->offset,
+				&md_io_clone->sectors, discard);
+	if (!md_io_clone->sectors)
+		return;
+	fn(mddev, md_io_clone->offset, md_io_clone->sectors);
+}
+
+static void md_bitmap_end(struct mddev *mddev, struct md_io_clone *md_io_clone)
+{
+	md_bitmap_fn *fn = unlikely(md_io_clone->rw == STAT_DISCARD) ?
+			   mddev->bitmap_ops->end_discard :
+			   mddev->bitmap_ops->end_write;
+
+	fn(mddev, md_io_clone->offset, md_io_clone->sectors);
+}
+
+static void md_end_clone_io(struct bio *bio)
+{
+	struct md_io_clone *md_io_clone = container_of(bio, struct md_io_clone,
+						       bio_clone);
+	struct bio *orig_bio = md_io_clone->orig_bio;
+	struct mddev *mddev = md_io_clone->mddev;
+	struct completion *reshape_completion = bio->bi_private;
+
+	if (bio_data_dir(orig_bio) == WRITE && md_io_clone->sectors &&
+	    md_bitmap_enabled(mddev, false))
+		md_bitmap_end(mddev, md_io_clone);
+
+	if (bio->bi_status && !orig_bio->bi_status)
+		orig_bio->bi_status = bio->bi_status;
+
+	if (md_io_clone->start_time)
+		bio_end_io_acct(orig_bio, md_io_clone->start_time);
+
+	bio_put(bio);
+	if (unlikely(reshape_completion))
+		complete(reshape_completion);
+	else
+		bio_endio(orig_bio);
+	percpu_ref_put(&mddev->active_io);
+}
+
+static void md_clone_bio(struct mddev *mddev, struct bio **bio)
+{
+	struct block_device *bdev = (*bio)->bi_bdev;
+	struct md_io_clone *md_io_clone;
+	struct bio *clone =
+		bio_alloc_clone(bdev, *bio, GFP_NOIO, &mddev->io_clone_set);
+
+	md_io_clone = container_of(clone, struct md_io_clone, bio_clone);
+	md_io_clone->orig_bio = *bio;
+	md_io_clone->mddev = mddev;
+	md_io_clone->sectors = 0;
+	if (blk_queue_io_stat(bdev->bd_disk->queue))
+		md_io_clone->start_time = bio_start_io_acct(*bio);
+	else
+		md_io_clone->start_time = 0;
+
+	if (bio_data_dir(*bio) == WRITE && bio_sectors(*bio) &&
+	    md_bitmap_enabled(mddev, false)) {
+		md_io_clone->offset = (*bio)->bi_iter.bi_sector;
+		md_io_clone->sectors = bio_sectors(*bio);
+		md_io_clone->rw = op_stat_group(bio_op(*bio));
+		md_bitmap_start(mddev, md_io_clone);
+	}
+
+	clone->bi_end_io = md_end_clone_io;
+	clone->bi_private = NULL;
+	*bio = clone;
+}
+
+void md_account_bio(struct mddev *mddev, struct bio **bio)
+{
+	percpu_ref_get(&mddev->active_io);
+	md_clone_bio(mddev, bio);
+}
+EXPORT_SYMBOL_GPL(md_account_bio);
+
+/* md_allow_write(mddev)
+ * Calling this ensures that the array is marked 'active' so that writes
+ * may proceed without blocking.  It is important to call this before
+ * attempting a GFP_KERNEL allocation while holding the mddev lock.
+ * Must be called with mddev_lock held.
+ */
+void md_allow_write(struct mddev *mddev)
+{
+	if (!mddev->pers)
+		return;
+	if (!md_is_rdwr(mddev))
+		return;
+	if (!mddev->pers->sync_request)
+		return;
+
+	spin_lock(&mddev->lock);
+	if (mddev->in_sync) {
+		mddev->in_sync = 0;
+		set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
+		set_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
+		if (mddev->safemode_delay &&
+		    mddev->safemode == 0)
+			mddev->safemode = 1;
+		spin_unlock(&mddev->lock);
+		md_update_sb(mddev, 0);
+		sysfs_notify_dirent_safe(mddev->sysfs_state);
+		/* wait for the dirty state to be recorded in the metadata */
+		wait_event(mddev->sb_wait,
+			   !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags));
+	} else
+		spin_unlock(&mddev->lock);
+}
+EXPORT_SYMBOL_GPL(md_allow_write);
+
+static sector_t md_sync_max_sectors(struct mddev *mddev,
+				    enum sync_action action)
+{
+	switch (action) {
+	case ACTION_RESYNC:
+	case ACTION_CHECK:
+	case ACTION_REPAIR:
+		atomic64_set(&mddev->resync_mismatches, 0);
+		fallthrough;
+	case ACTION_RESHAPE:
+		return mddev->resync_max_sectors;
+	case ACTION_RECOVER:
+		return mddev->dev_sectors;
+	default:
+		return 0;
+	}
+}
+
+/*
+ * If lazy recovery is requested and all rdevs are in sync, select the rdev with
+ * the higest index to perfore recovery to build initial xor data, this is the
+ * same as old bitmap.
+ */
+static bool mddev_select_lazy_recover_rdev(struct mddev *mddev)
+{
+	struct md_rdev *recover_rdev = NULL;
+	struct md_rdev *rdev;
+	bool ret = false;
+
+	rcu_read_lock();
+	rdev_for_each_rcu(rdev, mddev) {
+		if (rdev->raid_disk < 0)
+			continue;
+
+		if (test_bit(Faulty, &rdev->flags) ||
+		    !test_bit(In_sync, &rdev->flags))
+			break;
+
+		if (!recover_rdev || recover_rdev->raid_disk < rdev->raid_disk)
+			recover_rdev = rdev;
+	}
+
+	if (recover_rdev) {
+		clear_bit(In_sync, &recover_rdev->flags);
+		ret = true;
+	}
+
+	rcu_read_unlock();
+	return ret;
+}
+
+static sector_t md_sync_position(struct mddev *mddev, enum sync_action action)
+{
+	sector_t start = 0;
+	struct md_rdev *rdev;
+
+	switch (action) {
+	case ACTION_CHECK:
+	case ACTION_REPAIR:
+		return mddev->resync_min;
+	case ACTION_RESYNC:
+		if (!mddev->bitmap)
+			return mddev->resync_offset;
+		return 0;
+	case ACTION_RESHAPE:
+		/*
+		 * If the original node aborts reshaping then we continue the
+		 * reshaping, so set again to avoid restart reshape from the
+		 * first beginning
+		 */
+		if (mddev_is_clustered(mddev) &&
+		    mddev->reshape_position != MaxSector)
+			return mddev->reshape_position;
+		return 0;
+	case ACTION_RECOVER:
+		start = MaxSector;
+		rcu_read_lock();
+		rdev_for_each_rcu(rdev, mddev)
+			if (rdev_needs_recovery(rdev, start))
+				start = rdev->recovery_offset;
+		rcu_read_unlock();
+
+		/*
+		 * If there are no spares, and raid456 lazy initial recover is
+		 * requested.
+		 */
+		if (test_bit(MD_RECOVERY_LAZY_RECOVER, &mddev->recovery) &&
+		    start == MaxSector && mddev_select_lazy_recover_rdev(mddev))
+			start = 0;
+
+		/* If there is a bitmap, we need to make sure all
+		 * writes that started before we added a spare
+		 * complete before we start doing a recovery.
+		 * Otherwise the write might complete and (via
+		 * bitmap_endwrite) set a bit in the bitmap after the
+		 * recovery has checked that bit and skipped that
+		 * region.
+		 */
+		if (mddev->bitmap) {
+			mddev->pers->quiesce(mddev, 1);
+			mddev->pers->quiesce(mddev, 0);
+		}
+		return start;
+	default:
+		return MaxSector;
+	}
+}
+
+static bool sync_io_within_limit(struct mddev *mddev)
+{
+	/*
+	 * For raid456, sync IO is stripe(4k) per IO, for other levels, it's
+	 * RESYNC_PAGES(64k) per IO.
+	 */
+	return atomic_read(&mddev->recovery_active) <
+	       (raid_is_456(mddev) ? 8 : 128) * sync_io_depth(mddev);
+}
+
+/*
+ * Update sync offset and mddev status when sync completes
+ */
+static void md_finish_sync(struct mddev *mddev, enum sync_action action)
+{
+	struct md_rdev *rdev;
+
+	switch (action) {
+	case ACTION_RESYNC:
+	case ACTION_REPAIR:
+		if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery))
+			mddev->curr_resync = MaxSector;
+		mddev->resync_offset = mddev->curr_resync;
+		break;
+	case ACTION_RECOVER:
+		if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery))
+			mddev->curr_resync = MaxSector;
+		rcu_read_lock();
+		rdev_for_each_rcu(rdev, mddev)
+			if (mddev->delta_disks >= 0 &&
+			    rdev_needs_recovery(rdev, mddev->curr_resync))
+				rdev->recovery_offset = mddev->curr_resync;
+		rcu_read_unlock();
+		break;
+	case ACTION_RESHAPE:
+		if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
+		    mddev->delta_disks > 0 &&
+		    mddev->pers->finish_reshape &&
+		    mddev->pers->size &&
+		    !mddev_is_dm(mddev)) {
+			mddev_lock_nointr(mddev);
+			md_set_array_sectors(mddev, mddev->pers->size(mddev, 0, 0));
+			mddev_unlock(mddev);
+			if (!mddev_is_clustered(mddev))
+				set_capacity_and_notify(mddev->gendisk,
+							mddev->array_sectors);
+		}
+		if (mddev->pers->finish_reshape)
+			mddev->pers->finish_reshape(mddev);
+		break;
+	/* */
+	case ACTION_CHECK:
+	default:
+		break;
+	}
+}
+
+#define SYNC_MARKS	10
+#define	SYNC_MARK_STEP	(3*HZ)
+#define UPDATE_FREQUENCY (5*60*HZ)
+void md_do_sync(struct md_thread *thread)
+{
+	struct mddev *mddev = thread->mddev;
+	struct mddev *mddev2;
+	unsigned int currspeed = 0, window;
+	sector_t max_sectors,j, io_sectors, recovery_done;
+	unsigned long mark[SYNC_MARKS];
+	unsigned long update_time;
+	sector_t mark_cnt[SYNC_MARKS];
+	int last_mark,m;
+	sector_t last_check;
+	int skipped = 0;
+	enum sync_action action;
+	const char *desc;
+	struct blk_plug plug;
+	int ret;
+
+	/* just incase thread restarts... */
+	if (test_bit(MD_RECOVERY_DONE, &mddev->recovery))
+		return;
+
+	if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
+		goto skip;
+
+	if (test_bit(MD_RECOVERY_WAIT, &mddev->recovery) ||
+	    !md_is_rdwr(mddev)) {/* never try to sync a read-only array */
+		set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+		goto skip;
+	}
+
+	if (mddev_is_clustered(mddev)) {
+		ret = mddev->cluster_ops->resync_start(mddev);
+		if (ret)
+			goto skip;
+
+		set_bit(MD_CLUSTER_RESYNC_LOCKED, &mddev->flags);
+		if (!(test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
+			test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) ||
+			test_bit(MD_RECOVERY_RECOVER, &mddev->recovery))
+		     && ((unsigned long long)mddev->curr_resync_completed
+			 < (unsigned long long)mddev->resync_max_sectors))
+			goto skip;
+	}
+
+	action = md_sync_action(mddev);
+	if (action == ACTION_FROZEN || action == ACTION_IDLE) {
+		set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+		goto skip;
+	}
+
+	desc = md_sync_action_name(action);
+	mddev->last_sync_action = action;
+
+	/*
+	 * Before starting a resync we must have set curr_resync to
+	 * 2, and then checked that every "conflicting" array has curr_resync
+	 * less than ours.  When we find one that is the same or higher
+	 * we wait on resync_wait.  To avoid deadlock, we reduce curr_resync
+	 * to 1 if we choose to yield (based arbitrarily on address of mddev structure).
+	 * This will mean we have to start checking from the beginning again.
+	 *
+	 */
+	if (mddev_is_clustered(mddev))
+		mddev->cluster_ops->resync_start_notify(mddev);
+	do {
+		int mddev2_minor = -1;
+		mddev->curr_resync = MD_RESYNC_DELAYED;
+
+	try_again:
+		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
+			goto skip;
+		spin_lock(&all_mddevs_lock);
+		list_for_each_entry(mddev2, &all_mddevs, all_mddevs) {
+			if (test_bit(MD_DELETED, &mddev2->flags))
+				continue;
+			if (mddev2 == mddev)
+				continue;
+			if (!mddev->parallel_resync
+			&&  mddev2->curr_resync
+			&&  match_mddev_units(mddev, mddev2)) {
+				DEFINE_WAIT(wq);
+				if (mddev < mddev2 &&
+				    mddev->curr_resync == MD_RESYNC_DELAYED) {
+					/* arbitrarily yield */
+					mddev->curr_resync = MD_RESYNC_YIELDED;
+					wake_up(&resync_wait);
+				}
+				if (mddev > mddev2 &&
+				    mddev->curr_resync == MD_RESYNC_YIELDED)
+					/* no need to wait here, we can wait the next
+					 * time 'round when curr_resync == 2
+					 */
+					continue;
+				/* We need to wait 'interruptible' so as not to
+				 * contribute to the load average, and not to
+				 * be caught by 'softlockup'
+				 */
+				prepare_to_wait(&resync_wait, &wq, TASK_INTERRUPTIBLE);
+				if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
+				    mddev2->curr_resync >= mddev->curr_resync) {
+					if (mddev2_minor != mddev2->md_minor) {
+						mddev2_minor = mddev2->md_minor;
+						pr_info("md: delaying %s of %s until %s has finished (they share one or more physical units)\n",
+							desc, mdname(mddev),
+							mdname(mddev2));
+					}
+					spin_unlock(&all_mddevs_lock);
+
+					if (signal_pending(current))
+						flush_signals(current);
+					schedule();
+					finish_wait(&resync_wait, &wq);
+					goto try_again;
+				}
+				finish_wait(&resync_wait, &wq);
+			}
+		}
+		spin_unlock(&all_mddevs_lock);
+	} while (mddev->curr_resync < MD_RESYNC_DELAYED);
+
+	max_sectors = md_sync_max_sectors(mddev, action);
+	j = md_sync_position(mddev, action);
+
+	pr_info("md: %s of RAID array %s\n", desc, mdname(mddev));
+	pr_debug("md: minimum _guaranteed_  speed: %d KB/sec/disk.\n", speed_min(mddev));
+	pr_debug("md: using maximum available idle IO bandwidth (but not more than %d KB/sec) for %s.\n",
+		 speed_max(mddev), desc);
+
+	is_mddev_idle(mddev, 1); /* this initializes IO event counters */
+
+	io_sectors = 0;
+	for (m = 0; m < SYNC_MARKS; m++) {
+		mark[m] = jiffies;
+		mark_cnt[m] = io_sectors;
+	}
+	last_mark = 0;
+	mddev->resync_mark = mark[last_mark];
+	mddev->resync_mark_cnt = mark_cnt[last_mark];
+
+	/*
+	 * Tune reconstruction:
+	 */
+	window = 32 * (PAGE_SIZE / 512);
+	pr_debug("md: using %dk window, over a total of %lluk.\n",
+		 window/2, (unsigned long long)max_sectors/2);
+
+	atomic_set(&mddev->recovery_active, 0);
+	last_check = 0;
+
+	if (j >= MD_RESYNC_ACTIVE) {
+		pr_debug("md: resuming %s of %s from checkpoint.\n",
+			 desc, mdname(mddev));
+		mddev->curr_resync = j;
+	} else
+		mddev->curr_resync = MD_RESYNC_ACTIVE; /* no longer delayed */
+	mddev->curr_resync_completed = j;
+	sysfs_notify_dirent_safe(mddev->sysfs_completed);
+	md_new_event();
+	update_time = jiffies;
+
+	blk_start_plug(&plug);
+	while (j < max_sectors) {
+		sector_t sectors;
+
+		skipped = 0;
+
+		if (!test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
+		    ((mddev->curr_resync > mddev->curr_resync_completed &&
+		      (mddev->curr_resync - mddev->curr_resync_completed)
+		      > (max_sectors >> 4)) ||
+		     time_after_eq(jiffies, update_time + UPDATE_FREQUENCY) ||
+		     (j - mddev->curr_resync_completed)*2
+		     >= mddev->resync_max - mddev->curr_resync_completed ||
+		     mddev->curr_resync_completed > mddev->resync_max
+			    )) {
+			/* time to update curr_resync_completed */
+			wait_event(mddev->recovery_wait,
+				   atomic_read(&mddev->recovery_active) == 0);
+			mddev->curr_resync_completed = j;
+			if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) &&
+			    j > mddev->resync_offset)
+				mddev->resync_offset = j;
+			update_time = jiffies;
+			set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
+			sysfs_notify_dirent_safe(mddev->sysfs_completed);
+		}
+
+		while (j >= mddev->resync_max &&
+		       !test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
+			/* As this condition is controlled by user-space,
+			 * we can block indefinitely, so use '_interruptible'
+			 * to avoid triggering warnings.
+			 */
+			flush_signals(current); /* just in case */
+			wait_event_interruptible(mddev->recovery_wait,
+						 mddev->resync_max > j
+						 || test_bit(MD_RECOVERY_INTR,
+							     &mddev->recovery));
+		}
+
+		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
+			break;
+
+		if (mddev->bitmap_ops && mddev->bitmap_ops->skip_sync_blocks) {
+			sectors = mddev->bitmap_ops->skip_sync_blocks(mddev, j);
+			if (sectors)
+				goto update;
+		}
+
+		sectors = mddev->pers->sync_request(mddev, j, max_sectors,
+						    &skipped);
+		if (sectors == 0) {
+			set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+			break;
+		}
+
+		if (!skipped) { /* actual IO requested */
+			io_sectors += sectors;
+			atomic_add(sectors, &mddev->recovery_active);
+		}
+
+		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
+			break;
+
+update:
+		j += sectors;
+		if (j > max_sectors)
+			/* when skipping, extra large numbers can be returned. */
+			j = max_sectors;
+		if (j >= MD_RESYNC_ACTIVE)
+			mddev->curr_resync = j;
+		mddev->curr_mark_cnt = io_sectors;
+		if (last_check == 0)
+			/* this is the earliest that rebuild will be
+			 * visible in /proc/mdstat
+			 */
+			md_new_event();
+
+		if (last_check + window > io_sectors || j == max_sectors) {
+			cond_resched();
+			continue;
+		}
+
+		last_check = io_sectors;
+	repeat:
+		if (time_after_eq(jiffies, mark[last_mark] + SYNC_MARK_STEP )) {
+			/* step marks */
+			int next = (last_mark+1) % SYNC_MARKS;
+
+			mddev->resync_mark = mark[next];
+			mddev->resync_mark_cnt = mark_cnt[next];
+			mark[next] = jiffies;
+			mark_cnt[next] = io_sectors - atomic_read(&mddev->recovery_active);
+			last_mark = next;
+		}
+
+		if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
+			break;
+
+		/*
+		 * this loop exits only if either when we are slower than
+		 * the 'hard' speed limit, or the system was IO-idle for
+		 * a jiffy.
+		 * the system might be non-idle CPU-wise, but we only care
+		 * about not overloading the IO subsystem. (things like an
+		 * e2fsck being done on the RAID array should execute fast)
+		 */
+		cond_resched();
+
+		recovery_done = io_sectors - atomic_read(&mddev->recovery_active);
+		currspeed = ((unsigned long)(recovery_done - mddev->resync_mark_cnt))/2
+			/((jiffies-mddev->resync_mark)/HZ +1) +1;
+
+		if (currspeed > speed_min(mddev)) {
+			if (currspeed > speed_max(mddev)) {
+				msleep(500);
+				goto repeat;
+			}
+			if (!sync_io_within_limit(mddev) &&
+			    !is_mddev_idle(mddev, 0)) {
+				/*
+				 * Give other IO more of a chance.
+				 * The faster the devices, the less we wait.
+				 */
+				wait_event(mddev->recovery_wait,
+					   !atomic_read(&mddev->recovery_active));
+			}
+		}
+	}
+	pr_info("md: %s: %s %s.\n",mdname(mddev), desc,
+		test_bit(MD_RECOVERY_INTR, &mddev->recovery)
+		? "interrupted" : "done");
+	/*
+	 * this also signals 'finished resyncing' to md_stop
+	 */
+	blk_finish_plug(&plug);
+	wait_event(mddev->recovery_wait, !atomic_read(&mddev->recovery_active));
+
+	if (!test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) &&
+	    mddev->curr_resync >= MD_RESYNC_ACTIVE) {
+		/* All sync IO completes after recovery_active becomes 0 */
+		mddev->curr_resync_completed = mddev->curr_resync;
+		sysfs_notify_dirent_safe(mddev->sysfs_completed);
+	}
+	mddev->pers->sync_request(mddev, max_sectors, max_sectors, &skipped);
+
+	if (mddev->curr_resync > MD_RESYNC_ACTIVE)
+		md_finish_sync(mddev, action);
+ skip:
+	/* set CHANGE_PENDING here since maybe another update is needed,
+	 * so other nodes are informed. It should be harmless for normal
+	 * raid */
+	set_mask_bits(&mddev->sb_flags, 0,
+		      BIT(MD_SB_CHANGE_PENDING) | BIT(MD_SB_CHANGE_DEVS));
+	spin_lock(&mddev->lock);
+	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
+		/* We completed so min/max setting can be forgotten if used. */
+		if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
+			mddev->resync_min = 0;
+		mddev->resync_max = MaxSector;
+	} else if (test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
+		mddev->resync_min = mddev->curr_resync_completed;
+	set_bit(MD_RECOVERY_DONE, &mddev->recovery);
+	mddev->curr_resync = MD_RESYNC_NONE;
+	spin_unlock(&mddev->lock);
+
+	wake_up(&resync_wait);
+	md_wakeup_thread(mddev->thread);
+	return;
+}
+EXPORT_SYMBOL_GPL(md_do_sync);
+
+static bool rdev_removeable(struct md_rdev *rdev)
+{
+	/* rdev is not used. */
+	if (rdev->raid_disk < 0)
+		return false;
+
+	/* There are still inflight io, don't remove this rdev. */
+	if (atomic_read(&rdev->nr_pending))
+		return false;
+
+	/*
+	 * An error occurred but has not yet been acknowledged by the metadata
+	 * handler, don't remove this rdev.
+	 */
+	if (test_bit(Blocked, &rdev->flags))
+		return false;
+
+	/* Fautly rdev is not used, it's safe to remove it. */
+	if (test_bit(Faulty, &rdev->flags))
+		return true;
+
+	/* Journal disk can only be removed if it's faulty. */
+	if (test_bit(Journal, &rdev->flags))
+		return false;
+
+	/*
+	 * 'In_sync' is cleared while 'raid_disk' is valid, which means
+	 * replacement has just become active from pers->spare_active(), and
+	 * then pers->hot_remove_disk() will replace this rdev with replacement.
+	 */
+	if (!test_bit(In_sync, &rdev->flags))
+		return true;
+
+	return false;
+}
+
+static bool rdev_is_spare(struct md_rdev *rdev)
+{
+	return !test_bit(Candidate, &rdev->flags) && rdev->raid_disk >= 0 &&
+	       !test_bit(In_sync, &rdev->flags) &&
+	       !test_bit(Journal, &rdev->flags) &&
+	       !test_bit(Faulty, &rdev->flags);
+}
+
+static bool rdev_addable(struct md_rdev *rdev)
+{
+	struct mddev *mddev;
+
+	mddev = READ_ONCE(rdev->mddev);
+	if (!mddev)
+		return false;
+
+	/* rdev is already used, don't add it again. */
+	if (test_bit(Candidate, &rdev->flags) || rdev->raid_disk >= 0 ||
+	    test_bit(Faulty, &rdev->flags))
+		return false;
+
+	/* Allow to add journal disk. */
+	if (test_bit(Journal, &rdev->flags))
+		return true;
+
+	/* Allow to add if array is read-write. */
+	if (md_is_rdwr(mddev))
+		return true;
+
+	/*
+	 * For read-only array, only allow to readd a rdev. And if bitmap is
+	 * used, don't allow to readd a rdev that is too old.
+	 */
+	if (rdev->saved_raid_disk >= 0 && !test_bit(Bitmap_sync, &rdev->flags))
+		return true;
+
+	return false;
+}
+
+static bool md_spares_need_change(struct mddev *mddev)
+{
+	struct md_rdev *rdev;
+
+	rcu_read_lock();
+	rdev_for_each_rcu(rdev, mddev) {
+		if (rdev_removeable(rdev) || rdev_addable(rdev)) {
+			rcu_read_unlock();
+			return true;
+		}
+	}
+	rcu_read_unlock();
+	return false;
+}
+
+static int remove_spares(struct mddev *mddev, struct md_rdev *this)
+{
+	struct md_rdev *rdev;
+	int removed = 0;
+
+	rdev_for_each(rdev, mddev) {
+		if ((this == NULL || rdev == this) && rdev_removeable(rdev) &&
+		    !mddev->pers->hot_remove_disk(mddev, rdev)) {
+			sysfs_unlink_rdev(mddev, rdev);
+			rdev->saved_raid_disk = rdev->raid_disk;
+			rdev->raid_disk = -1;
+			removed++;
+		}
+	}
+
+	if (removed && mddev->kobj.sd)
+		sysfs_notify_dirent_safe(mddev->sysfs_degraded);
+
+	return removed;
+}
+
+static int remove_and_add_spares(struct mddev *mddev,
+				 struct md_rdev *this)
+{
+	struct md_rdev *rdev;
+	int spares = 0;
+	int removed = 0;
+
+	if (this && test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
+		/* Mustn't remove devices when resync thread is running */
+		return 0;
+
+	removed = remove_spares(mddev, this);
+	if (this && removed)
+		goto no_add;
+
+	rdev_for_each(rdev, mddev) {
+		if (this && this != rdev)
+			continue;
+		if (rdev_is_spare(rdev))
+			spares++;
+		if (!rdev_addable(rdev))
+			continue;
+		if (!test_bit(Journal, &rdev->flags))
+			rdev->recovery_offset = 0;
+		if (mddev->pers->hot_add_disk(mddev, rdev) == 0) {
+			/* failure here is OK */
+			sysfs_link_rdev(mddev, rdev);
+			if (!test_bit(Journal, &rdev->flags))
+				spares++;
+			md_new_event();
+			set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
+		}
+	}
+no_add:
+	if (removed)
+		set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
+	return spares;
+}
+
+static bool md_choose_sync_action(struct mddev *mddev, int *spares)
+{
+	/* Check if reshape is in progress first. */
+	if (mddev->reshape_position != MaxSector) {
+		if (mddev->pers->check_reshape == NULL ||
+		    mddev->pers->check_reshape(mddev) != 0)
+			return false;
+
+		set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
+		clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
+		clear_bit(MD_RECOVERY_LAZY_RECOVER, &mddev->recovery);
+		return true;
+	}
+
+	/* Check if resync is in progress. */
+	if (mddev->resync_offset < MaxSector) {
+		remove_spares(mddev, NULL);
+		set_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+		clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
+		clear_bit(MD_RECOVERY_LAZY_RECOVER, &mddev->recovery);
+		return true;
+	}
+
+	/*
+	 * Remove any failed drives, then add spares if possible. Spares are
+	 * also removed and re-added, to allow the personality to fail the
+	 * re-add.
+	 */
+	*spares = remove_and_add_spares(mddev, NULL);
+	if (*spares || test_bit(MD_RECOVERY_LAZY_RECOVER, &mddev->recovery)) {
+		clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+		clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
+		clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
+
+		/* Start new recovery. */
+		set_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
+		return true;
+	}
+
+	/* Delay to choose resync/check/repair in md_do_sync(). */
+	if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery))
+		return true;
+
+	/* Nothing to be done */
+	return false;
+}
+
+static void md_start_sync(struct work_struct *ws)
+{
+	struct mddev *mddev = container_of(ws, struct mddev, sync_work);
+	int spares = 0;
+	bool suspend = false;
+	unsigned int noio_flags = 0;
+	char *name;
+
+	/*
+	 * If reshape is still in progress, spares won't be added or removed
+	 * from conf until reshape is done.
+	 */
+	if ((mddev->reshape_position == MaxSector || !md_is_rdwr(mddev)) &&
+	    md_spares_need_change(mddev)) {
+		suspend = true;
+		mddev_suspend(mddev, false);
+		noio_flags = memalloc_noio_save();
+	}
+
+	mddev_lock_nointr(mddev);
+
+	/*
+	 * The spare configuration can change before reconfig_mutex is acquired.
+	 * Recheck while holding the lock and suspend if needed.
+	 */
+	if (!suspend && (mddev->reshape_position == MaxSector || !md_is_rdwr(mddev)) &&
+	    md_spares_need_change(mddev)) {
+		mddev_unlock(mddev);
+		mddev_suspend_and_lock_nointr(mddev);
+		suspend = true;
+		noio_flags = memalloc_noio_save();
+	}
+
+	if (!md_is_rdwr(mddev)) {
+		/*
+		 * On a read-only array we can:
+		 * - remove failed devices
+		 * - add already-in_sync devices if the array itself is in-sync.
+		 * As we only add devices that are already in-sync, we can
+		 * activate the spares immediately.
+		 */
+		remove_and_add_spares(mddev, NULL);
+		goto not_running;
+	}
+
+	if (!md_choose_sync_action(mddev, &spares))
+		goto not_running;
+
+	if (!mddev->pers->sync_request)
+		goto not_running;
+
+	/*
+	 * We are adding a device or devices to an array which has the bitmap
+	 * stored on all devices. So make sure all bitmap pages get written.
+	 */
+	if (spares && md_bitmap_enabled(mddev, true))
+		mddev->bitmap_ops->write_all(mddev);
+
+	name = test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery) ?
+			"reshape" : "resync";
+	rcu_assign_pointer(mddev->sync_thread,
+			   md_register_thread(md_do_sync, mddev, name));
+	if (!mddev->sync_thread) {
+		pr_warn("%s: could not start resync thread...\n",
+			mdname(mddev));
+		/* leave the spares where they are, it shouldn't hurt */
+		goto not_running;
+	}
+
+	mddev_unlock(mddev);
+	/*
+	 * md_start_sync was triggered by MD_RECOVERY_NEEDED, so we should
+	 * not set it again. Otherwise, we may cause issue like this one:
+	 *     https://bugzilla.kernel.org/show_bug.cgi?id=218200
+	 * Therefore, use __mddev_resume(mddev, false).
+	 */
+	if (suspend) {
+		memalloc_noio_restore(noio_flags);
+		__mddev_resume(mddev, false);
+	}
+	md_wakeup_thread(mddev->sync_thread);
+	sysfs_notify_dirent_safe(mddev->sysfs_action);
+	md_new_event();
+	return;
+
+not_running:
+	clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+	clear_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
+	clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
+	clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
+	clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
+	mddev_unlock(mddev);
+	/*
+	 * md_start_sync was triggered by MD_RECOVERY_NEEDED, so we should
+	 * not set it again. Otherwise, we may cause issue like this one:
+	 *     https://bugzilla.kernel.org/show_bug.cgi?id=218200
+	 * Therefore, use __mddev_resume(mddev, false).
+	 */
+	if (suspend) {
+		memalloc_noio_restore(noio_flags);
+		__mddev_resume(mddev, false);
+	}
+
+	wake_up(&resync_wait);
+	if (test_and_clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery) &&
+	    mddev->sysfs_action)
+		sysfs_notify_dirent_safe(mddev->sysfs_action);
+}
+
+static void unregister_sync_thread(struct mddev *mddev)
+{
+	if (!test_bit(MD_RECOVERY_DONE, &mddev->recovery)) {
+		/* resync/recovery still happening */
+		clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+		return;
+	}
+
+	if (WARN_ON_ONCE(!mddev->sync_thread))
+		return;
+
+	md_reap_sync_thread(mddev);
+}
+
+static bool md_should_do_recovery(struct mddev *mddev)
+{
+	/*
+	 * As long as one of the following flags is set,
+	 * recovery needs to do or cleanup.
+	 */
+	if (test_bit(MD_RECOVERY_NEEDED, &mddev->recovery) ||
+	    test_bit(MD_RECOVERY_DONE, &mddev->recovery))
+		return true;
+
+	/*
+	 * If no flags are set and it is in read-only status,
+	 * there is nothing to do.
+	 */
+	if (!md_is_rdwr(mddev))
+		return false;
+
+	/*
+	 * MD_SB_CHANGE_PENDING indicates that the array is switching from clean to
+	 * active, and no action is needed for now.
+	 * All other MD_SB_* flags require to update the superblock.
+	 */
+	if (mddev->sb_flags & ~ (1<<MD_SB_CHANGE_PENDING))
+		return true;
+
+	/*
+	 * If the array is not using external metadata and there has been no data
+	 * written for some time, then the array's status needs to be set to
+	 * in_sync.
+	 */
+	if (mddev->external == 0 && mddev->safemode == 1)
+		return true;
+
+	/*
+	 * When the system is about to restart or the process receives an signal,
+	 * the array needs to be synchronized as soon as possible.
+	 * Once the data synchronization is completed, need to change the array
+	 * status to in_sync.
+	 */
+	if (mddev->safemode == 2 && !mddev->in_sync &&
+	    mddev->resync_offset == MaxSector)
+		return true;
+
+	return false;
+}
+
+/*
+ * This routine is regularly called by all per-raid-array threads to
+ * deal with generic issues like resync and super-block update.
+ * Raid personalities that don't have a thread (linear/raid0) do not
+ * need this as they never do any recovery or update the superblock.
+ *
+ * It does not do any resync itself, but rather "forks" off other threads
+ * to do that as needed.
+ * When it is determined that resync is needed, we set MD_RECOVERY_RUNNING in
+ * "->recovery" and create a thread at ->sync_thread.
+ * When the thread finishes it sets MD_RECOVERY_DONE
+ * and wakeups up this thread which will reap the thread and finish up.
+ * This thread also removes any faulty devices (with nr_pending == 0).
+ *
+ * The overall approach is:
+ *  1/ if the superblock needs updating, update it.
+ *  2/ If a recovery thread is running, don't do anything else.
+ *  3/ If recovery has finished, clean up, possibly marking spares active.
+ *  4/ If there are any faulty devices, remove them.
+ *  5/ If array is degraded, try to add spares devices
+ *  6/ If array has spares or is not in-sync, start a resync thread.
+ */
+void md_check_recovery(struct mddev *mddev)
+{
+	if (md_bitmap_enabled(mddev, false) && mddev->bitmap_ops->daemon_work)
+		mddev->bitmap_ops->daemon_work(mddev);
+
+	if (signal_pending(current)) {
+		if (mddev->pers->sync_request && !mddev->external) {
+			pr_debug("md: %s in immediate safe mode\n",
+				 mdname(mddev));
+			mddev->safemode = 2;
+		}
+		flush_signals(current);
+	}
+
+	if (!md_should_do_recovery(mddev))
+		return;
+
+	if (mddev_trylock(mddev)) {
+		bool try_set_sync = mddev->safemode != 0;
+
+		if (!mddev->external && mddev->safemode == 1)
+			mddev->safemode = 0;
+
+		if (!md_is_rdwr(mddev)) {
+			struct md_rdev *rdev;
+
+			if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) {
+				unregister_sync_thread(mddev);
+				goto unlock;
+			}
+
+			if (!mddev->external && mddev->in_sync)
+				/*
+				 * 'Blocked' flag not needed as failed devices
+				 * will be recorded if array switched to read/write.
+				 * Leaving it set will prevent the device
+				 * from being removed.
+				 */
+				rdev_for_each(rdev, mddev)
+					clear_bit(Blocked, &rdev->flags);
+
+			/*
+			 * There is no thread, but we need to call
+			 * ->spare_active and clear saved_raid_disk
+			 */
+			set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+			md_reap_sync_thread(mddev);
+
+			/*
+			 * Let md_start_sync() to remove and add rdevs to the
+			 * array.
+			 */
+			if (md_spares_need_change(mddev)) {
+				set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
+				queue_work(md_misc_wq, &mddev->sync_work);
+			}
+
+			clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery);
+			clear_bit(MD_RECOVERY_LAZY_RECOVER, &mddev->recovery);
+			clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+			clear_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
+
+			goto unlock;
+		}
+
+		if (mddev_is_clustered(mddev)) {
+			struct md_rdev *rdev, *tmp;
+			/* kick the device if another node issued a
+			 * remove disk.
+			 */
+			rdev_for_each_safe(rdev, tmp, mddev) {
+				if (rdev->raid_disk < 0 &&
+				    test_and_clear_bit(ClusterRemove, &rdev->flags))
+					md_kick_rdev_from_array(rdev);
+			}
+		}
+
+		if (try_set_sync && !mddev->external && !mddev->in_sync) {
+			spin_lock(&mddev->lock);
+			set_in_sync(mddev);
+			spin_unlock(&mddev->lock);
+		}
+
+		if (mddev->sb_flags)
+			md_update_sb(mddev, 0);
+
+		/*
+		 * Never start a new sync thread if MD_RECOVERY_RUNNING is
+		 * still set.
+		 */
+		if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) {
+			unregister_sync_thread(mddev);
+			goto unlock;
+		}
+
+		/* Set RUNNING before clearing NEEDED to avoid
+		 * any transients in the value of "sync_action".
+		 */
+		mddev->curr_resync_completed = 0;
+		spin_lock(&mddev->lock);
+		set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
+		spin_unlock(&mddev->lock);
+		/* Clear some bits that don't mean anything, but
+		 * might be left set
+		 */
+		clear_bit(MD_RECOVERY_INTR, &mddev->recovery);
+		clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
+
+		if (test_and_clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery) &&
+		    !test_bit(MD_RECOVERY_FROZEN, &mddev->recovery)) {
+			queue_work(md_misc_wq, &mddev->sync_work);
+		} else {
+			clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
+			wake_up(&resync_wait);
+		}
+
+	unlock:
+		wake_up(&mddev->sb_wait);
+		mddev_unlock(mddev);
+	}
+}
+EXPORT_SYMBOL(md_check_recovery);
+
+void md_reap_sync_thread(struct mddev *mddev)
+{
+	struct md_rdev *rdev;
+	sector_t old_dev_sectors = mddev->dev_sectors;
+	bool is_reshaped = test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
+
+	/* resync has finished, collect result */
+	md_unregister_thread(mddev, &mddev->sync_thread);
+	atomic_inc(&mddev->sync_seq);
+
+	if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
+	    !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
+	    mddev->degraded != mddev->raid_disks) {
+		/* success...*/
+		/* activate any spares */
+		if (mddev->pers->spare_active(mddev)) {
+			sysfs_notify_dirent_safe(mddev->sysfs_degraded);
+			set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
+		}
+	}
+
+	/* If array is no-longer degraded, then any saved_raid_disk
+	 * information must be scrapped.
+	 */
+	if (!mddev->degraded)
+		rdev_for_each(rdev, mddev)
+			rdev->saved_raid_disk = -1;
+
+	md_update_sb(mddev, 1);
+	/* MD_SB_CHANGE_PENDING should be cleared by md_update_sb, so we can
+	 * call resync_finish here if MD_CLUSTER_RESYNC_LOCKED is set by
+	 * clustered raid */
+	if (test_and_clear_bit(MD_CLUSTER_RESYNC_LOCKED, &mddev->flags))
+		mddev->cluster_ops->resync_finish(mddev);
+	clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
+	clear_bit(MD_RECOVERY_DONE, &mddev->recovery);
+	clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
+	clear_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
+	clear_bit(MD_RECOVERY_REQUESTED, &mddev->recovery);
+	clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
+	clear_bit(MD_RECOVERY_LAZY_RECOVER, &mddev->recovery);
+	/*
+	 * We call mddev->cluster_ops->update_size here because sync_size could
+	 * be changed by md_update_sb, and MD_RECOVERY_RESHAPE is cleared,
+	 * so it is time to update size across cluster.
+	 */
+	if (mddev_is_clustered(mddev) && is_reshaped &&
+	    mddev->pers->finish_reshape &&
+	    !test_bit(MD_CLOSING, &mddev->flags))
+		mddev->cluster_ops->update_size(mddev, old_dev_sectors);
+	/* flag recovery needed just to double check */
+	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+	sysfs_notify_dirent_safe(mddev->sysfs_completed);
+	sysfs_notify_dirent_safe(mddev->sysfs_action);
+	md_new_event();
+	if (mddev->event_work.func)
+		queue_work(md_misc_wq, &mddev->event_work);
+	wake_up(&resync_wait);
+}
+EXPORT_SYMBOL(md_reap_sync_thread);
+
+void md_wait_for_blocked_rdev(struct md_rdev *rdev, struct mddev *mddev)
+{
+	sysfs_notify_dirent_safe(rdev->sysfs_state);
+	wait_event_timeout(rdev->blocked_wait, !rdev_blocked(rdev),
+			   msecs_to_jiffies(5000));
+	rdev_dec_pending(rdev, mddev);
+}
+EXPORT_SYMBOL(md_wait_for_blocked_rdev);
+
+void md_finish_reshape(struct mddev *mddev)
+{
+	/* called be personality module when reshape completes. */
+	struct md_rdev *rdev;
+
+	rdev_for_each(rdev, mddev) {
+		if (rdev->data_offset > rdev->new_data_offset)
+			rdev->sectors += rdev->data_offset - rdev->new_data_offset;
+		else
+			rdev->sectors -= rdev->new_data_offset - rdev->data_offset;
+		rdev->data_offset = rdev->new_data_offset;
+	}
+}
+EXPORT_SYMBOL(md_finish_reshape);
+
+/* Bad block management */
+
+/* Returns true on success, false on failure */
+bool rdev_set_badblocks(struct md_rdev *rdev, sector_t s, sector_t sectors,
+			int is_new)
+{
+	struct mddev *mddev = rdev->mddev;
+
+	/*
+	 * Recording new badblocks for faulty rdev will force unnecessary
+	 * super block updating. This is fragile for external management because
+	 * userspace daemon may trying to remove this device and deadlock may
+	 * occur. This will be probably solved in the mdadm, but it is safer to
+	 * avoid it.
+	 */
+	if (test_bit(Faulty, &rdev->flags))
+		return true;
+
+	if (is_new)
+		s += rdev->new_data_offset;
+	else
+		s += rdev->data_offset;
+
+	if (!badblocks_set(&rdev->badblocks, s, sectors, 0)) {
+		/*
+		 * Mark the disk as Faulty when setting badblocks fails,
+		 * otherwise, bad sectors may be read.
+		 */
+		md_error(mddev, rdev);
+		return false;
+	}
+
+	/* Make sure they get written out promptly */
+	if (test_bit(ExternalBbl, &rdev->flags))
+		sysfs_notify_dirent_safe(rdev->sysfs_unack_badblocks);
+	sysfs_notify_dirent_safe(rdev->sysfs_state);
+	set_mask_bits(&mddev->sb_flags, 0,
+		      BIT(MD_SB_CHANGE_CLEAN) | BIT(MD_SB_CHANGE_PENDING));
+	md_wakeup_thread(rdev->mddev->thread);
+	return true;
+}
+EXPORT_SYMBOL_GPL(rdev_set_badblocks);
+
+void rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, sector_t sectors,
+			  int is_new)
+{
+	if (is_new)
+		s += rdev->new_data_offset;
+	else
+		s += rdev->data_offset;
+
+	if (!badblocks_clear(&rdev->badblocks, s, sectors))
+		return;
+
+	if (test_bit(ExternalBbl, &rdev->flags))
+		sysfs_notify_dirent_safe(rdev->sysfs_badblocks);
+}
+EXPORT_SYMBOL_GPL(rdev_clear_badblocks);
+
+static int md_notify_reboot(struct notifier_block *this,
+			    unsigned long code, void *x)
+{
+	struct mddev *mddev;
+
+	spin_lock(&all_mddevs_lock);
+	list_for_each_entry(mddev, &all_mddevs, all_mddevs) {
+		if (!mddev_get(mddev))
+			continue;
+		spin_unlock(&all_mddevs_lock);
+		if (mddev_trylock(mddev)) {
+			if (mddev->pers)
+				__md_stop_writes(mddev);
+			if (mddev->persistent)
+				mddev->safemode = 2;
+			mddev_unlock(mddev);
+		}
+		spin_lock(&all_mddevs_lock);
+		mddev_put_locked(mddev);
+	}
+	spin_unlock(&all_mddevs_lock);
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block md_notifier = {
+	.notifier_call	= md_notify_reboot,
+	.next		= NULL,
+	.priority	= INT_MAX, /* before any real devices */
+};
+
+static void md_geninit(void)
+{
+	pr_debug("md: sizeof(mdp_super_t) = %d\n", (int)sizeof(mdp_super_t));
+
+	proc_create("mdstat", S_IRUGO, NULL, &mdstat_proc_ops);
+}
+
+static int __init md_init(void)
+{
+	int ret = md_bitmap_init();
+
+	if (ret)
+		return ret;
+
+	ret = md_llbitmap_init();
+	if (ret)
+		goto err_bitmap;
+
+	ret = -ENOMEM;
+	md_misc_wq = alloc_workqueue("md_misc", WQ_PERCPU, 0);
+	if (!md_misc_wq)
+		goto err_misc_wq;
+
+	ret = __register_blkdev(MD_MAJOR, "md", md_probe);
+	if (ret < 0)
+		goto err_md;
+
+	ret = __register_blkdev(0, "mdp", md_probe);
+	if (ret < 0)
+		goto err_mdp;
+	mdp_major = ret;
+
+	register_reboot_notifier(&md_notifier);
+	raid_table_header = register_sysctl("dev/raid", raid_table);
+
+	md_geninit();
+	return 0;
+
+err_mdp:
+	unregister_blkdev(MD_MAJOR, "md");
+err_md:
+	destroy_workqueue(md_misc_wq);
+err_misc_wq:
+	md_llbitmap_exit();
+err_bitmap:
+	md_bitmap_exit();
+	return ret;
+}
+
+static void check_sb_changes(struct mddev *mddev, struct md_rdev *rdev)
+{
+	struct mdp_superblock_1 *sb = page_address(rdev->sb_page);
+	struct md_rdev *rdev2, *tmp;
+	int role, ret;
+
+	/*
+	 * If size is changed in another node then we need to
+	 * do resize as well.
+	 */
+	if (mddev->dev_sectors != le64_to_cpu(sb->size)) {
+		ret = mddev->pers->resize(mddev, le64_to_cpu(sb->size));
+		if (ret)
+			pr_info("md-cluster: resize failed\n");
+		else if (md_bitmap_enabled(mddev, false))
+			mddev->bitmap_ops->update_sb(mddev->bitmap);
+	}
+
+	/* Check for change of roles in the active devices */
+	rdev_for_each_safe(rdev2, tmp, mddev) {
+		if (test_bit(Faulty, &rdev2->flags)) {
+			if (test_bit(ClusterRemove, &rdev2->flags))
+				set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+			continue;
+		}
+
+		/* Check if the roles changed */
+		role = le16_to_cpu(sb->dev_roles[rdev2->desc_nr]);
+
+		if (test_bit(Candidate, &rdev2->flags)) {
+			if (role == MD_DISK_ROLE_FAULTY) {
+				pr_info("md: Removing Candidate device %pg because add failed\n",
+					rdev2->bdev);
+				md_kick_rdev_from_array(rdev2);
+				continue;
+			}
+			else
+				clear_bit(Candidate, &rdev2->flags);
+		}
+
+		if (role != rdev2->raid_disk) {
+			/*
+			 * got activated except reshape is happening.
+			 */
+			if (rdev2->raid_disk == -1 && role != MD_DISK_ROLE_SPARE &&
+			    !(le32_to_cpu(sb->feature_map) &
+			      MD_FEATURE_RESHAPE_ACTIVE) &&
+			    !mddev->cluster_ops->resync_status_get(mddev)) {
+				/*
+				 * -1 to make raid1_add_disk() set conf->fullsync
+				 * to 1. This could avoid skipping sync when the
+				 * remote node is down during resyncing.
+				 */
+				if ((le32_to_cpu(sb->feature_map)
+				    & MD_FEATURE_RECOVERY_OFFSET))
+					rdev2->saved_raid_disk = -1;
+				else
+					rdev2->saved_raid_disk = role;
+				ret = remove_and_add_spares(mddev, rdev2);
+				pr_info("Activated spare: %pg\n",
+					rdev2->bdev);
+				/* wakeup mddev->thread here, so array could
+				 * perform resync with the new activated disk */
+				set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
+				md_wakeup_thread(mddev->thread);
+			}
+			/* device faulty
+			 * We just want to do the minimum to mark the disk
+			 * as faulty. The recovery is performed by the
+			 * one who initiated the error.
+			 */
+			if (role == MD_DISK_ROLE_FAULTY ||
+			    role == MD_DISK_ROLE_JOURNAL) {
+				md_error(mddev, rdev2);
+				clear_bit(Blocked, &rdev2->flags);
+			}
+		}
+	}
+
+	if (mddev->raid_disks != le32_to_cpu(sb->raid_disks)) {
+		ret = update_raid_disks(mddev, le32_to_cpu(sb->raid_disks));
+		if (ret)
+			pr_warn("md: updating array disks failed. %d\n", ret);
+	}
+
+	/*
+	 * Since mddev->delta_disks has already updated in update_raid_disks,
+	 * so it is time to check reshape.
+	 */
+	if (test_bit(MD_RESYNCING_REMOTE, &mddev->recovery) &&
+	    (le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE)) {
+		/*
+		 * reshape is happening in the remote node, we need to
+		 * update reshape_position and call start_reshape.
+		 */
+		mddev->reshape_position = le64_to_cpu(sb->reshape_position);
+		if (mddev->pers->update_reshape_pos)
+			mddev->pers->update_reshape_pos(mddev);
+		if (mddev->pers->start_reshape)
+			mddev->pers->start_reshape(mddev);
+	} else if (test_bit(MD_RESYNCING_REMOTE, &mddev->recovery) &&
+		   mddev->reshape_position != MaxSector &&
+		   !(le32_to_cpu(sb->feature_map) & MD_FEATURE_RESHAPE_ACTIVE)) {
+		/* reshape is just done in another node. */
+		mddev->reshape_position = MaxSector;
+		if (mddev->pers->update_reshape_pos)
+			mddev->pers->update_reshape_pos(mddev);
+	}
+
+	/* Finally set the event to be up to date */
+	mddev->events = le64_to_cpu(sb->events);
+}
+
+static int read_rdev(struct mddev *mddev, struct md_rdev *rdev)
+{
+	int err;
+	struct page *swapout = rdev->sb_page;
+	struct mdp_superblock_1 *sb;
+
+	/* Store the sb page of the rdev in the swapout temporary
+	 * variable in case we err in the future
+	 */
+	rdev->sb_page = NULL;
+	err = alloc_disk_sb(rdev);
+	if (err == 0) {
+		ClearPageUptodate(rdev->sb_page);
+		rdev->sb_loaded = 0;
+		err = super_types[mddev->major_version].
+			load_super(rdev, NULL, mddev->minor_version);
+	}
+	if (err < 0) {
+		pr_warn("%s: %d Could not reload rdev(%d) err: %d. Restoring old values\n",
+				__func__, __LINE__, rdev->desc_nr, err);
+		if (rdev->sb_page)
+			put_page(rdev->sb_page);
+		rdev->sb_page = swapout;
+		rdev->sb_loaded = 1;
+		return err;
+	}
+
+	sb = page_address(rdev->sb_page);
+	/* Read the offset unconditionally, even if MD_FEATURE_RECOVERY_OFFSET
+	 * is not set
+	 */
+
+	if ((le32_to_cpu(sb->feature_map) & MD_FEATURE_RECOVERY_OFFSET))
+		rdev->recovery_offset = le64_to_cpu(sb->recovery_offset);
+
+	/* The other node finished recovery, call spare_active to set
+	 * device In_sync and mddev->degraded
+	 */
+	if (rdev->recovery_offset == MaxSector &&
+	    !test_bit(In_sync, &rdev->flags) &&
+	    mddev->pers->spare_active(mddev))
+		sysfs_notify_dirent_safe(mddev->sysfs_degraded);
+
+	put_page(swapout);
+	return 0;
+}
+
+void md_reload_sb(struct mddev *mddev, int nr)
+{
+	struct md_rdev *rdev = NULL, *iter;
+	int err;
+
+	/* Find the rdev */
+	rdev_for_each_rcu(iter, mddev) {
+		if (iter->desc_nr == nr) {
+			rdev = iter;
+			break;
+		}
+	}
+
+	if (!rdev) {
+		pr_warn("%s: %d Could not find rdev with nr %d\n", __func__, __LINE__, nr);
+		return;
+	}
+
+	err = read_rdev(mddev, rdev);
+	if (err < 0)
+		return;
+
+	check_sb_changes(mddev, rdev);
+
+	/* Read all rdev's to update recovery_offset */
+	rdev_for_each_rcu(rdev, mddev) {
+		if (!test_bit(Faulty, &rdev->flags))
+			read_rdev(mddev, rdev);
+	}
+}
+EXPORT_SYMBOL(md_reload_sb);
+
+#ifndef MODULE
+
+/*
+ * Searches all registered partitions for autorun RAID arrays
+ * at boot time.
+ */
+
+static DEFINE_MUTEX(detected_devices_mutex);
+static LIST_HEAD(all_detected_devices);
+struct detected_devices_node {
+	struct list_head list;
+	dev_t dev;
+};
+
+void md_autodetect_dev(dev_t dev)
+{
+	struct detected_devices_node *node_detected_dev;
+
+	node_detected_dev = kzalloc_obj(*node_detected_dev);
+	if (node_detected_dev) {
+		node_detected_dev->dev = dev;
+		mutex_lock(&detected_devices_mutex);
+		list_add_tail(&node_detected_dev->list, &all_detected_devices);
+		mutex_unlock(&detected_devices_mutex);
+	}
+}
+
+void md_autostart_arrays(int part)
+{
+	struct md_rdev *rdev;
+	struct detected_devices_node *node_detected_dev;
+	dev_t dev;
+	int i_scanned, i_passed;
+
+	i_scanned = 0;
+	i_passed = 0;
+
+	pr_info("md: Autodetecting RAID arrays.\n");
+
+	mutex_lock(&detected_devices_mutex);
+	while (!list_empty(&all_detected_devices) && i_scanned < INT_MAX) {
+		i_scanned++;
+		node_detected_dev = list_entry(all_detected_devices.next,
+					struct detected_devices_node, list);
+		list_del(&node_detected_dev->list);
+		dev = node_detected_dev->dev;
+		kfree(node_detected_dev);
+		mutex_unlock(&detected_devices_mutex);
+		rdev = md_import_device(dev,0, 90);
+		mutex_lock(&detected_devices_mutex);
+		if (IS_ERR(rdev))
+			continue;
+
+		if (test_bit(Faulty, &rdev->flags))
+			continue;
+
+		set_bit(AutoDetected, &rdev->flags);
+		list_add(&rdev->same_set, &pending_raid_disks);
+		i_passed++;
+	}
+	mutex_unlock(&detected_devices_mutex);
+
+	pr_debug("md: Scanned %d and added %d devices.\n", i_scanned, i_passed);
+
+	autorun_devices(part);
+}
+
+#endif /* !MODULE */
+
+static __exit void md_exit(void)
+{
+	struct mddev *mddev;
+	int delay = 1;
+
+	unregister_blkdev(MD_MAJOR,"md");
+	unregister_blkdev(mdp_major, "mdp");
+	unregister_reboot_notifier(&md_notifier);
+	unregister_sysctl_table(raid_table_header);
+
+	/* We cannot unload the modules while some process is
+	 * waiting for us in select() or poll() - wake them up
+	 */
+	md_unloading = 1;
+	while (waitqueue_active(&md_event_waiters)) {
+		/* not safe to leave yet */
+		wake_up(&md_event_waiters);
+		msleep(delay);
+		delay += delay;
+	}
+	remove_proc_entry("mdstat", NULL);
+
+	spin_lock(&all_mddevs_lock);
+	list_for_each_entry(mddev, &all_mddevs, all_mddevs) {
+		if (!mddev_get(mddev))
+			continue;
+		spin_unlock(&all_mddevs_lock);
+		export_array(mddev);
+		mddev->ctime = 0;
+		mddev->hold_active = 0;
+		/*
+		 * As the mddev is now fully clear, mddev_put will schedule
+		 * the mddev for destruction by a workqueue, and the
+		 * destroy_workqueue() below will wait for that to complete.
+		 */
+		spin_lock(&all_mddevs_lock);
+		mddev_put_locked(mddev);
+	}
+	spin_unlock(&all_mddevs_lock);
+
+	destroy_workqueue(md_misc_wq);
+	md_bitmap_exit();
+}
+
+subsys_initcall(md_init);
+module_exit(md_exit)
+
+static int get_ro(char *buffer, const struct kernel_param *kp)
+{
+	return sprintf(buffer, "%d\n", start_readonly);
+}
+static int set_ro(const char *val, const struct kernel_param *kp)
+{
+	return kstrtouint(val, 10, (unsigned int *)&start_readonly);
+}
+
+module_param_call(start_ro, set_ro, get_ro, NULL, S_IRUSR|S_IWUSR);
+module_param(start_dirty_degraded, int, S_IRUGO|S_IWUSR);
+module_param_call(new_array, add_named_array, NULL, NULL, S_IWUSR);
+module_param(create_on_open, bool, S_IRUSR|S_IWUSR);
+module_param(legacy_async_del_gendisk, bool, 0600);
+module_param(check_new_feature, bool, 0600);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("MD RAID framework");
+MODULE_ALIAS("md");
+MODULE_ALIAS_BLOCKDEV_MAJOR(MD_MAJOR);