Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 684 insertions, 0 deletions

diff --git a/fs/affs/super.c b/fs/affs/super.c
new file mode 100644
index 000000000..ed8225b3c
--- /dev/null
+++ b/fs/affs/super.c
@@ -0,0 +1,684 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/fs/affs/inode.c
+ *
+ *  (c) 1996  Hans-Joachim Widmaier - Rewritten
+ *
+ *  (C) 1993  Ray Burr - Modified for Amiga FFS filesystem.
+ *
+ *  (C) 1992  Eric Youngdale Modified for ISO 9660 filesystem.
+ *
+ *  (C) 1991  Linus Torvalds - minix filesystem
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/statfs.h>
+#include <linux/fs_parser.h>
+#include <linux/fs_context.h>
+#include <linux/magic.h>
+#include <linux/sched.h>
+#include <linux/cred.h>
+#include <linux/slab.h>
+#include <linux/writeback.h>
+#include <linux/blkdev.h>
+#include <linux/seq_file.h>
+#include <linux/iversion.h>
+#include "affs.h"
+
+static int affs_statfs(struct dentry *dentry, struct kstatfs *buf);
+static int affs_show_options(struct seq_file *m, struct dentry *root);
+
+static void
+affs_commit_super(struct super_block *sb, int wait)
+{
+	struct affs_sb_info *sbi = AFFS_SB(sb);
+	struct buffer_head *bh = sbi->s_root_bh;
+	struct affs_root_tail *tail = AFFS_ROOT_TAIL(sb, bh);
+
+	lock_buffer(bh);
+	affs_secs_to_datestamp(ktime_get_real_seconds(), &tail->disk_change);
+	affs_fix_checksum(sb, bh);
+	unlock_buffer(bh);
+
+	mark_buffer_dirty(bh);
+	if (wait)
+		sync_dirty_buffer(bh);
+}
+
+static void
+affs_put_super(struct super_block *sb)
+{
+	struct affs_sb_info *sbi = AFFS_SB(sb);
+	pr_debug("%s()\n", __func__);
+
+	cancel_delayed_work_sync(&sbi->sb_work);
+}
+
+static int
+affs_sync_fs(struct super_block *sb, int wait)
+{
+	affs_commit_super(sb, wait);
+	return 0;
+}
+
+static void flush_superblock(struct work_struct *work)
+{
+	struct affs_sb_info *sbi;
+	struct super_block *sb;
+
+	sbi = container_of(work, struct affs_sb_info, sb_work.work);
+	sb = sbi->sb;
+
+	spin_lock(&sbi->work_lock);
+	sbi->work_queued = 0;
+	spin_unlock(&sbi->work_lock);
+
+	affs_commit_super(sb, 1);
+}
+
+void affs_mark_sb_dirty(struct super_block *sb)
+{
+	struct affs_sb_info *sbi = AFFS_SB(sb);
+	unsigned long delay;
+
+	if (sb_rdonly(sb))
+	       return;
+
+	spin_lock(&sbi->work_lock);
+	if (!sbi->work_queued) {
+	       delay = msecs_to_jiffies(dirty_writeback_interval * 10);
+	       queue_delayed_work(system_dfl_long_wq, &sbi->sb_work, delay);
+	       sbi->work_queued = 1;
+	}
+	spin_unlock(&sbi->work_lock);
+}
+
+static struct kmem_cache * affs_inode_cachep;
+
+static struct inode *affs_alloc_inode(struct super_block *sb)
+{
+	struct affs_inode_info *i;
+
+	i = alloc_inode_sb(sb, affs_inode_cachep, GFP_KERNEL);
+	if (!i)
+		return NULL;
+
+	inode_set_iversion(&i->vfs_inode, 1);
+	i->i_lc = NULL;
+	i->i_ext_bh = NULL;
+	i->i_pa_cnt = 0;
+
+	return &i->vfs_inode;
+}
+
+static void affs_free_inode(struct inode *inode)
+{
+	kmem_cache_free(affs_inode_cachep, AFFS_I(inode));
+}
+
+static void init_once(void *foo)
+{
+	struct affs_inode_info *ei = (struct affs_inode_info *) foo;
+
+	mutex_init(&ei->i_link_lock);
+	mutex_init(&ei->i_ext_lock);
+	inode_init_once(&ei->vfs_inode);
+}
+
+static int __init init_inodecache(void)
+{
+	affs_inode_cachep = kmem_cache_create("affs_inode_cache",
+					     sizeof(struct affs_inode_info),
+					     0, (SLAB_RECLAIM_ACCOUNT | SLAB_ACCOUNT),
+					     init_once);
+	if (affs_inode_cachep == NULL)
+		return -ENOMEM;
+	return 0;
+}
+
+static void destroy_inodecache(void)
+{
+	/*
+	 * Make sure all delayed rcu free inodes are flushed before we
+	 * destroy cache.
+	 */
+	rcu_barrier();
+	kmem_cache_destroy(affs_inode_cachep);
+}
+
+static const struct super_operations affs_sops = {
+	.alloc_inode	= affs_alloc_inode,
+	.free_inode	= affs_free_inode,
+	.write_inode	= affs_write_inode,
+	.evict_inode	= affs_evict_inode,
+	.put_super	= affs_put_super,
+	.sync_fs	= affs_sync_fs,
+	.statfs		= affs_statfs,
+	.show_options	= affs_show_options,
+};
+
+enum {
+	Opt_bs, Opt_mode, Opt_mufs, Opt_notruncate, Opt_prefix, Opt_protect,
+	Opt_reserved, Opt_root, Opt_setgid, Opt_setuid,
+	Opt_verbose, Opt_volume, Opt_ignore,
+};
+
+struct affs_context {
+	kuid_t		uid;		/* uid to override */
+	kgid_t		gid;		/* gid to override */
+	unsigned int	mode;		/* mode to override */
+	unsigned int	reserved;	/* Number of reserved blocks */
+	int		root_block;	/* FFS root block number */
+	int		blocksize;	/* Initial device blksize */
+	char		*prefix;	/* Prefix for volumes and assigns */
+	char		volume[32];	/* Vol. prefix for absolute symlinks */
+	unsigned long	mount_flags;	/* Options */
+};
+
+static const struct fs_parameter_spec affs_param_spec[] = {
+	fsparam_u32	("bs",		Opt_bs),
+	fsparam_u32oct	("mode",	Opt_mode),
+	fsparam_flag	("mufs",	Opt_mufs),
+	fsparam_flag	("nofilenametruncate",	Opt_notruncate),
+	fsparam_string	("prefix",	Opt_prefix),
+	fsparam_flag	("protect",	Opt_protect),
+	fsparam_u32	("reserved",	Opt_reserved),
+	fsparam_u32	("root",	Opt_root),
+	fsparam_gid	("setgid",	Opt_setgid),
+	fsparam_uid	("setuid",	Opt_setuid),
+	fsparam_flag	("verbose",	Opt_verbose),
+	fsparam_string	("volume",	Opt_volume),
+	fsparam_flag	("grpquota",	Opt_ignore),
+	fsparam_flag	("noquota",	Opt_ignore),
+	fsparam_flag	("quota",	Opt_ignore),
+	fsparam_flag	("usrquota",	Opt_ignore),
+	{},
+};
+
+static int affs_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+	struct affs_context *ctx = fc->fs_private;
+	struct fs_parse_result result;
+	int n;
+	int opt;
+
+	opt = fs_parse(fc, affs_param_spec, param, &result);
+	if (opt < 0)
+		return opt;
+
+	switch (opt) {
+	case Opt_bs:
+		n = result.uint_32;
+		if (n != 512 && n != 1024 && n != 2048
+		    && n != 4096) {
+			pr_warn("Invalid blocksize (512, 1024, 2048, 4096 allowed)\n");
+			return -EINVAL;
+		}
+		ctx->blocksize = n;
+		break;
+	case Opt_mode:
+		ctx->mode = result.uint_32 & 0777;
+		affs_set_opt(ctx->mount_flags, SF_SETMODE);
+		break;
+	case Opt_mufs:
+		affs_set_opt(ctx->mount_flags, SF_MUFS);
+		break;
+	case Opt_notruncate:
+		affs_set_opt(ctx->mount_flags, SF_NO_TRUNCATE);
+		break;
+	case Opt_prefix:
+		kfree(ctx->prefix);
+		ctx->prefix = param->string;
+		param->string = NULL;
+		affs_set_opt(ctx->mount_flags, SF_PREFIX);
+		break;
+	case Opt_protect:
+		affs_set_opt(ctx->mount_flags, SF_IMMUTABLE);
+		break;
+	case Opt_reserved:
+		ctx->reserved = result.uint_32;
+		break;
+	case Opt_root:
+		ctx->root_block = result.uint_32;
+		break;
+	case Opt_setgid:
+		ctx->gid = result.gid;
+		affs_set_opt(ctx->mount_flags, SF_SETGID);
+		break;
+	case Opt_setuid:
+		ctx->uid = result.uid;
+		affs_set_opt(ctx->mount_flags, SF_SETUID);
+		break;
+	case Opt_verbose:
+		affs_set_opt(ctx->mount_flags, SF_VERBOSE);
+		break;
+	case Opt_volume:
+		strscpy(ctx->volume, param->string, 32);
+		break;
+	case Opt_ignore:
+		/* Silently ignore the quota options */
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int affs_show_options(struct seq_file *m, struct dentry *root)
+{
+	struct super_block *sb = root->d_sb;
+	struct affs_sb_info *sbi = AFFS_SB(sb);
+
+	if (sb->s_blocksize)
+		seq_printf(m, ",bs=%lu", sb->s_blocksize);
+	if (affs_test_opt(sbi->s_flags, SF_SETMODE))
+		seq_printf(m, ",mode=%o", sbi->s_mode);
+	if (affs_test_opt(sbi->s_flags, SF_MUFS))
+		seq_puts(m, ",mufs");
+	if (affs_test_opt(sbi->s_flags, SF_NO_TRUNCATE))
+		seq_puts(m, ",nofilenametruncate");
+	if (affs_test_opt(sbi->s_flags, SF_PREFIX))
+		seq_printf(m, ",prefix=%s", sbi->s_prefix);
+	if (affs_test_opt(sbi->s_flags, SF_IMMUTABLE))
+		seq_puts(m, ",protect");
+	if (sbi->s_reserved != 2)
+		seq_printf(m, ",reserved=%u", sbi->s_reserved);
+	if (sbi->s_root_block != (sbi->s_reserved + sbi->s_partition_size - 1) / 2)
+		seq_printf(m, ",root=%u", sbi->s_root_block);
+	if (affs_test_opt(sbi->s_flags, SF_SETGID))
+		seq_printf(m, ",setgid=%u",
+			   from_kgid_munged(&init_user_ns, sbi->s_gid));
+	if (affs_test_opt(sbi->s_flags, SF_SETUID))
+		seq_printf(m, ",setuid=%u",
+			   from_kuid_munged(&init_user_ns, sbi->s_uid));
+	if (affs_test_opt(sbi->s_flags, SF_VERBOSE))
+		seq_puts(m, ",verbose");
+	if (sbi->s_volume[0])
+		seq_printf(m, ",volume=%s", sbi->s_volume);
+	return 0;
+}
+
+/* This function definitely needs to be split up. Some fine day I'll
+ * hopefully have the guts to do so. Until then: sorry for the mess.
+ */
+
+static int affs_fill_super(struct super_block *sb, struct fs_context *fc)
+{
+	struct affs_sb_info	*sbi;
+	struct affs_context	*ctx = fc->fs_private;
+	struct buffer_head	*root_bh = NULL;
+	struct buffer_head	*boot_bh;
+	struct inode		*root_inode = NULL;
+	int			 silent = fc->sb_flags & SB_SILENT;
+	int			 size, blocksize;
+	u32			 chksum;
+	int			 num_bm;
+	int			 i, j;
+	int			 tmp_flags;	/* fix remount prototype... */
+	u8			 sig[4];
+	int			 ret;
+
+	sb->s_magic             = AFFS_SUPER_MAGIC;
+	sb->s_op                = &affs_sops;
+	sb->s_flags |= SB_NODIRATIME;
+
+	sb->s_time_gran = NSEC_PER_SEC;
+	sb->s_time_min = sys_tz.tz_minuteswest * 60 + AFFS_EPOCH_DELTA;
+	sb->s_time_max = 86400LL * U32_MAX + 86400 + sb->s_time_min;
+
+	sbi = kzalloc_obj(struct affs_sb_info);
+	if (!sbi)
+		return -ENOMEM;
+
+	sb->s_fs_info = sbi;
+	sbi->sb = sb;
+	mutex_init(&sbi->s_bmlock);
+	spin_lock_init(&sbi->symlink_lock);
+	spin_lock_init(&sbi->work_lock);
+	INIT_DELAYED_WORK(&sbi->sb_work, flush_superblock);
+
+	sbi->s_flags	= ctx->mount_flags;
+	sbi->s_mode	= ctx->mode;
+	sbi->s_uid	= ctx->uid;
+	sbi->s_gid	= ctx->gid;
+	sbi->s_reserved	= ctx->reserved;
+	sbi->s_prefix	= ctx->prefix;
+	ctx->prefix	= NULL;
+	memcpy(sbi->s_volume, ctx->volume, 32);
+
+	/* N.B. after this point s_prefix must be released */
+
+	/* Get the size of the device in 512-byte blocks.
+	 * If we later see that the partition uses bigger
+	 * blocks, we will have to change it.
+	 */
+
+	size = bdev_nr_sectors(sb->s_bdev);
+	pr_debug("initial blocksize=%d, #blocks=%d\n", 512, size);
+
+	if (!sb_set_blocksize(sb, PAGE_SIZE))
+		return -EINVAL;
+	/* Try to find root block. Its location depends on the block size. */
+
+	i = bdev_logical_block_size(sb->s_bdev);
+	j = PAGE_SIZE;
+	blocksize = ctx->blocksize;
+	if (blocksize > 0) {
+		i = j = blocksize;
+		size = size / (blocksize / 512);
+	}
+
+	for (blocksize = i; blocksize <= j; blocksize <<= 1, size >>= 1) {
+		sbi->s_root_block = ctx->root_block;
+		if (ctx->root_block < 0)
+			sbi->s_root_block = (ctx->reserved + size - 1) / 2;
+		pr_debug("setting blocksize to %d\n", blocksize);
+		if (!sb_set_blocksize(sb, blocksize))
+			return -EINVAL;
+		sbi->s_partition_size = size;
+
+		/* The root block location that was calculated above is not
+		 * correct if the partition size is an odd number of 512-
+		 * byte blocks, which will be rounded down to a number of
+		 * 1024-byte blocks, and if there were an even number of
+		 * reserved blocks. Ideally, all partition checkers should
+		 * report the real number of blocks of the real blocksize,
+		 * but since this just cannot be done, we have to try to
+		 * find the root block anyways. In the above case, it is one
+		 * block behind the calculated one. So we check this one, too.
+		 */
+		for (num_bm = 0; num_bm < 2; num_bm++) {
+			pr_debug("Dev %s, trying root=%u, bs=%d, "
+				"size=%d, reserved=%d\n",
+				sb->s_id,
+				sbi->s_root_block + num_bm,
+				ctx->blocksize, size, ctx->reserved);
+			root_bh = affs_bread(sb, sbi->s_root_block + num_bm);
+			if (!root_bh)
+				continue;
+			if (!affs_checksum_block(sb, root_bh) &&
+			    be32_to_cpu(AFFS_ROOT_HEAD(root_bh)->ptype) == T_SHORT &&
+			    be32_to_cpu(AFFS_ROOT_TAIL(sb, root_bh)->stype) == ST_ROOT) {
+				sbi->s_hashsize    = blocksize / 4 - 56;
+				sbi->s_root_block += num_bm;
+				goto got_root;
+			}
+			affs_brelse(root_bh);
+			root_bh = NULL;
+		}
+	}
+	if (!silent)
+		pr_err("No valid root block on device %s\n", sb->s_id);
+	return -EINVAL;
+
+	/* N.B. after this point bh must be released */
+got_root:
+	/* Keep super block in cache */
+	sbi->s_root_bh = root_bh;
+	ctx->root_block = sbi->s_root_block;
+
+	/* Find out which kind of FS we have */
+	boot_bh = sb_bread(sb, 0);
+	if (!boot_bh) {
+		pr_err("Cannot read boot block\n");
+		return -EINVAL;
+	}
+	memcpy(sig, boot_bh->b_data, 4);
+	brelse(boot_bh);
+	chksum = be32_to_cpu(*(__be32 *)sig);
+
+	/* Dircache filesystems are compatible with non-dircache ones
+	 * when reading. As long as they aren't supported, writing is
+	 * not recommended.
+	 */
+	if ((chksum == FS_DCFFS || chksum == MUFS_DCFFS || chksum == FS_DCOFS
+	     || chksum == MUFS_DCOFS) && !sb_rdonly(sb)) {
+		pr_notice("Dircache FS - mounting %s read only\n", sb->s_id);
+		sb->s_flags |= SB_RDONLY;
+	}
+	switch (chksum) {
+	case MUFS_FS:
+	case MUFS_INTLFFS:
+	case MUFS_DCFFS:
+		affs_set_opt(sbi->s_flags, SF_MUFS);
+		fallthrough;
+	case FS_INTLFFS:
+	case FS_DCFFS:
+		affs_set_opt(sbi->s_flags, SF_INTL);
+		break;
+	case MUFS_FFS:
+		affs_set_opt(sbi->s_flags, SF_MUFS);
+		break;
+	case FS_FFS:
+		break;
+	case MUFS_OFS:
+		affs_set_opt(sbi->s_flags, SF_MUFS);
+		fallthrough;
+	case FS_OFS:
+		affs_set_opt(sbi->s_flags, SF_OFS);
+		sb->s_flags |= SB_NOEXEC;
+		break;
+	case MUFS_DCOFS:
+	case MUFS_INTLOFS:
+		affs_set_opt(sbi->s_flags, SF_MUFS);
+		fallthrough;
+	case FS_DCOFS:
+	case FS_INTLOFS:
+		affs_set_opt(sbi->s_flags, SF_INTL);
+		affs_set_opt(sbi->s_flags, SF_OFS);
+		sb->s_flags |= SB_NOEXEC;
+		break;
+	default:
+		pr_err("Unknown filesystem on device %s: %08X\n",
+		       sb->s_id, chksum);
+		return -EINVAL;
+	}
+
+	if (affs_test_opt(ctx->mount_flags, SF_VERBOSE)) {
+		u8 len = AFFS_ROOT_TAIL(sb, root_bh)->disk_name[0];
+		pr_notice("Mounting volume \"%.*s\": Type=%.3s\\%c, Blocksize=%d\n",
+			len > 31 ? 31 : len,
+			AFFS_ROOT_TAIL(sb, root_bh)->disk_name + 1,
+			sig, sig[3] + '0', blocksize);
+	}
+
+	sb->s_flags |= SB_NODEV | SB_NOSUID;
+
+	sbi->s_data_blksize = sb->s_blocksize;
+	if (affs_test_opt(sbi->s_flags, SF_OFS))
+		sbi->s_data_blksize -= 24;
+
+	tmp_flags = sb->s_flags;
+	ret = affs_init_bitmap(sb, &tmp_flags);
+	if (ret)
+		return ret;
+	sb->s_flags = tmp_flags;
+
+	/* set up enough so that it can read an inode */
+
+	root_inode = affs_iget(sb, ctx->root_block);
+	if (IS_ERR(root_inode))
+		return PTR_ERR(root_inode);
+
+	if (affs_test_opt(AFFS_SB(sb)->s_flags, SF_INTL))
+		set_default_d_op(sb, &affs_intl_dentry_operations);
+	else
+		set_default_d_op(sb, &affs_dentry_operations);
+
+	sb->s_root = d_make_root(root_inode);
+	if (!sb->s_root) {
+		pr_err("AFFS: Get root inode failed\n");
+		return -ENOMEM;
+	}
+
+	sb->s_export_op = &affs_export_ops;
+	pr_debug("s_flags=%lX\n", sb->s_flags);
+	return 0;
+}
+
+static int affs_reconfigure(struct fs_context *fc)
+{
+	struct super_block	*sb = fc->root->d_sb;
+	struct affs_context	*ctx = fc->fs_private;
+	struct affs_sb_info	*sbi = AFFS_SB(sb);
+	int			 res = 0;
+
+	sync_filesystem(sb);
+	fc->sb_flags |= SB_NODIRATIME;
+
+	flush_delayed_work(&sbi->sb_work);
+
+	/*
+	 * NB: Historically, only mount_flags, mode, uid, gic, prefix,
+	 * and volume are accepted during remount.
+	 */
+	sbi->s_flags = ctx->mount_flags;
+	sbi->s_mode  = ctx->mode;
+	sbi->s_uid   = ctx->uid;
+	sbi->s_gid   = ctx->gid;
+	/* protect against readers */
+	spin_lock(&sbi->symlink_lock);
+	if (ctx->prefix) {
+		kfree(sbi->s_prefix);
+		sbi->s_prefix = ctx->prefix;
+		ctx->prefix = NULL;
+	}
+	memcpy(sbi->s_volume, ctx->volume, 32);
+	spin_unlock(&sbi->symlink_lock);
+
+	if ((bool)(fc->sb_flags & SB_RDONLY) == sb_rdonly(sb))
+		return 0;
+
+	if (fc->sb_flags & SB_RDONLY)
+		affs_free_bitmap(sb);
+	else
+		res = affs_init_bitmap(sb, &fc->sb_flags);
+
+	return res;
+}
+
+static int
+affs_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+	struct super_block *sb = dentry->d_sb;
+	int		 free;
+	u64		 id = huge_encode_dev(sb->s_bdev->bd_dev);
+
+	pr_debug("%s() partsize=%d, reserved=%d\n",
+		 __func__, AFFS_SB(sb)->s_partition_size,
+		 AFFS_SB(sb)->s_reserved);
+
+	free          = affs_count_free_blocks(sb);
+	buf->f_type    = AFFS_SUPER_MAGIC;
+	buf->f_bsize   = sb->s_blocksize;
+	buf->f_blocks  = AFFS_SB(sb)->s_partition_size - AFFS_SB(sb)->s_reserved;
+	buf->f_bfree   = free;
+	buf->f_bavail  = free;
+	buf->f_fsid    = u64_to_fsid(id);
+	buf->f_namelen = AFFSNAMEMAX;
+	return 0;
+}
+
+static int affs_get_tree(struct fs_context *fc)
+{
+	return get_tree_bdev(fc, affs_fill_super);
+}
+
+static void affs_kill_sb(struct super_block *sb)
+{
+	struct affs_sb_info *sbi = AFFS_SB(sb);
+	kill_block_super(sb);
+	if (sbi) {
+		affs_free_bitmap(sb);
+		affs_brelse(sbi->s_root_bh);
+		kfree(sbi->s_prefix);
+		mutex_destroy(&sbi->s_bmlock);
+		kfree_rcu(sbi, rcu);
+	}
+}
+
+static void affs_free_fc(struct fs_context *fc)
+{
+	struct affs_context *ctx = fc->fs_private;
+
+	kfree(ctx->prefix);
+	kfree(ctx);
+}
+
+static const struct fs_context_operations affs_context_ops = {
+	.parse_param	= affs_parse_param,
+	.get_tree	= affs_get_tree,
+	.reconfigure	= affs_reconfigure,
+	.free		= affs_free_fc,
+};
+
+static int affs_init_fs_context(struct fs_context *fc)
+{
+	struct affs_context *ctx;
+
+	ctx = kzalloc_obj(struct affs_context);
+	if (!ctx)
+		return -ENOMEM;
+
+	if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) {
+		struct super_block *sb = fc->root->d_sb;
+		struct affs_sb_info *sbi = AFFS_SB(sb);
+
+		/*
+		 * NB: historically, no options other than volume were
+		 * preserved across a remount unless they were explicitly
+		 * passed in.
+		 */
+		memcpy(ctx->volume, sbi->s_volume, 32);
+	} else {
+		ctx->uid	= current_uid();
+		ctx->gid	= current_gid();
+		ctx->reserved	= 2;
+		ctx->root_block	= -1;
+		ctx->blocksize	= -1;
+		ctx->volume[0]	= ':';
+	}
+
+	fc->ops = &affs_context_ops;
+	fc->fs_private = ctx;
+
+	return 0;
+}
+
+static struct file_system_type affs_fs_type = {
+	.owner		= THIS_MODULE,
+	.name		= "affs",
+	.kill_sb	= affs_kill_sb,
+	.fs_flags	= FS_REQUIRES_DEV,
+	.init_fs_context = affs_init_fs_context,
+	.parameters	= affs_param_spec,
+};
+MODULE_ALIAS_FS("affs");
+
+static int __init init_affs_fs(void)
+{
+	int err = init_inodecache();
+	if (err)
+		goto out1;
+	err = register_filesystem(&affs_fs_type);
+	if (err)
+		goto out;
+	return 0;
+out:
+	destroy_inodecache();
+out1:
+	return err;
+}
+
+static void __exit exit_affs_fs(void)
+{
+	unregister_filesystem(&affs_fs_type);
+	destroy_inodecache();
+}
+
+MODULE_DESCRIPTION("Amiga filesystem support for Linux");
+MODULE_LICENSE("GPL");
+
+module_init(init_affs_fs)
+module_exit(exit_affs_fs)