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, 678 insertions, 0 deletions

diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c
new file mode 100644
index 000000000..29c0d6941
--- /dev/null
+++ b/drivers/mtd/ubi/block.c
@@ -0,0 +1,678 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2014 Ezequiel Garcia
+ * Copyright (c) 2011 Free Electrons
+ *
+ * Driver parameter handling strongly based on drivers/mtd/ubi/build.c
+ *   Copyright (c) International Business Machines Corp., 2006
+ *   Copyright (c) Nokia Corporation, 2007
+ *   Authors: Artem Bityutskiy, Frank Haverkamp
+ */
+
+/*
+ * Read-only block devices on top of UBI volumes
+ *
+ * A simple implementation to allow a block device to be layered on top of a
+ * UBI volume. The implementation is provided by creating a static 1-to-1
+ * mapping between the block device and the UBI volume.
+ *
+ * The addressed byte is obtained from the addressed block sector, which is
+ * mapped linearly into the corresponding LEB:
+ *
+ *   LEB number = addressed byte / LEB size
+ *
+ * This feature is compiled in the UBI core, and adds a 'block' parameter
+ * to allow early creation of block devices on top of UBI volumes. Runtime
+ * block creation/removal for UBI volumes is provided through two UBI ioctls:
+ * UBI_IOCVOLCRBLK and UBI_IOCVOLRMBLK.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/mtd/ubi.h>
+#include <linux/blkdev.h>
+#include <linux/blk-mq.h>
+#include <linux/hdreg.h>
+#include <linux/scatterlist.h>
+#include <linux/idr.h>
+#include <asm/div64.h>
+
+#include "ubi-media.h"
+#include "ubi.h"
+
+/* Maximum number of supported devices */
+#define UBIBLOCK_MAX_DEVICES 32
+
+/* Maximum length of the 'block=' parameter */
+#define UBIBLOCK_PARAM_LEN 63
+
+/* Maximum number of comma-separated items in the 'block=' parameter */
+#define UBIBLOCK_PARAM_COUNT 2
+
+struct ubiblock_param {
+	int ubi_num;
+	int vol_id;
+	char name[UBIBLOCK_PARAM_LEN+1];
+};
+
+struct ubiblock_pdu {
+	struct ubi_sgl usgl;
+};
+
+/* Numbers of elements set in the @ubiblock_param array */
+static int ubiblock_devs;
+
+/* MTD devices specification parameters */
+static struct ubiblock_param ubiblock_param[UBIBLOCK_MAX_DEVICES];
+
+struct ubiblock {
+	struct ubi_volume_desc *desc;
+	int ubi_num;
+	int vol_id;
+	int refcnt;
+	int leb_size;
+
+	struct gendisk *gd;
+	struct request_queue *rq;
+
+	struct mutex dev_mutex;
+	struct list_head list;
+	struct blk_mq_tag_set tag_set;
+};
+
+/* Linked list of all ubiblock instances */
+static LIST_HEAD(ubiblock_devices);
+static DEFINE_IDR(ubiblock_minor_idr);
+/* Protects ubiblock_devices and ubiblock_minor_idr */
+static DEFINE_MUTEX(devices_mutex);
+static int ubiblock_major;
+
+static int __init ubiblock_set_param(const char *val,
+				     const struct kernel_param *kp)
+{
+	int i, ret;
+	size_t len;
+	struct ubiblock_param *param;
+	char buf[UBIBLOCK_PARAM_LEN];
+	char *pbuf = &buf[0];
+	char *tokens[UBIBLOCK_PARAM_COUNT];
+
+	if (!val)
+		return -EINVAL;
+
+	len = strnlen(val, UBIBLOCK_PARAM_LEN);
+	if (len == 0) {
+		pr_warn("UBI: block: empty 'block=' parameter - ignored\n");
+		return 0;
+	}
+
+	if (len == UBIBLOCK_PARAM_LEN) {
+		pr_err("UBI: block: parameter \"%s\" is too long, max. is %d\n",
+		       val, UBIBLOCK_PARAM_LEN);
+		return -EINVAL;
+	}
+
+	strcpy(buf, val);
+
+	/* Get rid of the final newline */
+	if (buf[len - 1] == '\n')
+		buf[len - 1] = '\0';
+
+	for (i = 0; i < UBIBLOCK_PARAM_COUNT; i++)
+		tokens[i] = strsep(&pbuf, ",");
+
+	param = &ubiblock_param[ubiblock_devs];
+	if (tokens[1]) {
+		/* Two parameters: can be 'ubi, vol_id' or 'ubi, vol_name' */
+		ret = kstrtoint(tokens[0], 10, &param->ubi_num);
+		if (ret < 0)
+			return -EINVAL;
+
+		/* Second param can be a number or a name */
+		ret = kstrtoint(tokens[1], 10, &param->vol_id);
+		if (ret < 0) {
+			param->vol_id = -1;
+			strcpy(param->name, tokens[1]);
+		}
+
+	} else {
+		/* One parameter: must be device path */
+		strcpy(param->name, tokens[0]);
+		param->ubi_num = -1;
+		param->vol_id = -1;
+	}
+
+	ubiblock_devs++;
+
+	return 0;
+}
+
+static const struct kernel_param_ops ubiblock_param_ops = {
+	.set    = ubiblock_set_param,
+};
+module_param_cb(block, &ubiblock_param_ops, NULL, 0);
+MODULE_PARM_DESC(block, "Attach block devices to UBI volumes. Parameter format: block=<path|dev,num|dev,name>.\n"
+			"Multiple \"block\" parameters may be specified.\n"
+			"UBI volumes may be specified by their number, name, or path to the device node.\n"
+			"Examples\n"
+			"Using the UBI volume path:\n"
+			"ubi.block=/dev/ubi0_0\n"
+			"Using the UBI device, and the volume name:\n"
+			"ubi.block=0,rootfs\n"
+			"Using both UBI device number and UBI volume number:\n"
+			"ubi.block=0,0\n");
+
+static struct ubiblock *find_dev_nolock(int ubi_num, int vol_id)
+{
+	struct ubiblock *dev;
+
+	list_for_each_entry(dev, &ubiblock_devices, list)
+		if (dev->ubi_num == ubi_num && dev->vol_id == vol_id)
+			return dev;
+	return NULL;
+}
+
+static blk_status_t ubiblock_read(struct request *req)
+{
+	struct ubiblock_pdu *pdu = blk_mq_rq_to_pdu(req);
+	struct ubiblock *dev = req->q->queuedata;
+	u64 pos = blk_rq_pos(req) << 9;
+	int to_read = blk_rq_bytes(req);
+	int bytes_left = to_read;
+	/* Get LEB:offset address to read from */
+	int offset = do_div(pos, dev->leb_size);
+	int leb = pos;
+	struct req_iterator iter;
+	struct bio_vec bvec;
+	int ret;
+
+	blk_mq_start_request(req);
+
+	/*
+	 * It is safe to ignore the return value of blk_rq_map_sg() because
+	 * the number of sg entries is limited to UBI_MAX_SG_COUNT
+	 * and ubi_read_sg() will check that limit.
+	 */
+	ubi_sgl_init(&pdu->usgl);
+	blk_rq_map_sg(req, pdu->usgl.sg);
+
+	while (bytes_left) {
+		/*
+		 * We can only read one LEB at a time. Therefore if the read
+		 * length is larger than one LEB size, we split the operation.
+		 */
+		if (offset + to_read > dev->leb_size)
+			to_read = dev->leb_size - offset;
+
+		ret = ubi_read_sg(dev->desc, leb, &pdu->usgl, offset, to_read);
+		if (ret < 0)
+			break;
+
+		bytes_left -= to_read;
+		to_read = bytes_left;
+		leb += 1;
+		offset = 0;
+	}
+
+	rq_for_each_segment(bvec, req, iter)
+		flush_dcache_page(bvec.bv_page);
+
+	blk_mq_end_request(req, errno_to_blk_status(ret));
+
+	return BLK_STS_OK;
+}
+
+static int ubiblock_open(struct gendisk *disk, blk_mode_t mode)
+{
+	struct ubiblock *dev = disk->private_data;
+	int ret;
+
+	mutex_lock(&dev->dev_mutex);
+	if (dev->refcnt > 0) {
+		/*
+		 * The volume is already open, just increase the reference
+		 * counter.
+		 */
+		goto out_done;
+	}
+
+	/*
+	 * We want users to be aware they should only mount us as read-only.
+	 * It's just a paranoid check, as write requests will get rejected
+	 * in any case.
+	 */
+	if (mode & BLK_OPEN_WRITE) {
+		ret = -EROFS;
+		goto out_unlock;
+	}
+	dev->desc = ubi_open_volume(dev->ubi_num, dev->vol_id, UBI_READONLY);
+	if (IS_ERR(dev->desc)) {
+		dev_err(disk_to_dev(dev->gd), "failed to open ubi volume %d_%d",
+			dev->ubi_num, dev->vol_id);
+		ret = PTR_ERR(dev->desc);
+		dev->desc = NULL;
+		goto out_unlock;
+	}
+
+out_done:
+	dev->refcnt++;
+	mutex_unlock(&dev->dev_mutex);
+	return 0;
+
+out_unlock:
+	mutex_unlock(&dev->dev_mutex);
+	return ret;
+}
+
+static void ubiblock_release(struct gendisk *gd)
+{
+	struct ubiblock *dev = gd->private_data;
+
+	mutex_lock(&dev->dev_mutex);
+	dev->refcnt--;
+	if (dev->refcnt == 0) {
+		ubi_close_volume(dev->desc);
+		dev->desc = NULL;
+	}
+	mutex_unlock(&dev->dev_mutex);
+}
+
+static int ubiblock_getgeo(struct gendisk *disk, struct hd_geometry *geo)
+{
+	/* Some tools might require this information */
+	geo->heads = 1;
+	geo->cylinders = 1;
+	geo->sectors = get_capacity(disk);
+	geo->start = 0;
+	return 0;
+}
+
+static const struct block_device_operations ubiblock_ops = {
+	.owner = THIS_MODULE,
+	.open = ubiblock_open,
+	.release = ubiblock_release,
+	.getgeo	= ubiblock_getgeo,
+};
+
+static blk_status_t ubiblock_queue_rq(struct blk_mq_hw_ctx *hctx,
+			     const struct blk_mq_queue_data *bd)
+{
+	switch (req_op(bd->rq)) {
+	case REQ_OP_READ:
+		return ubiblock_read(bd->rq);
+	default:
+		return BLK_STS_IOERR;
+	}
+}
+
+static int ubiblock_init_request(struct blk_mq_tag_set *set,
+		struct request *req, unsigned int hctx_idx,
+		int numa_node)
+{
+	struct ubiblock_pdu *pdu = blk_mq_rq_to_pdu(req);
+
+	sg_init_table(pdu->usgl.sg, UBI_MAX_SG_COUNT);
+	return 0;
+}
+
+static const struct blk_mq_ops ubiblock_mq_ops = {
+	.queue_rq       = ubiblock_queue_rq,
+	.init_request	= ubiblock_init_request,
+};
+
+static int calc_disk_capacity(struct ubi_volume_info *vi, u64 *disk_capacity)
+{
+	u64 size = vi->used_bytes >> 9;
+
+	if (vi->used_bytes % 512) {
+		if (vi->vol_type == UBI_DYNAMIC_VOLUME)
+			pr_warn("UBI: block: volume size is not a multiple of 512, last %llu bytes are ignored!\n",
+				vi->used_bytes - (size << 9));
+		else
+			pr_info("UBI: block: volume size is not a multiple of 512, last %llu bytes are ignored!\n",
+				vi->used_bytes - (size << 9));
+	}
+
+	if ((sector_t)size != size)
+		return -EFBIG;
+
+	*disk_capacity = size;
+
+	return 0;
+}
+
+int ubiblock_create(struct ubi_volume_info *vi)
+{
+	struct queue_limits lim = {
+		.max_segments		= UBI_MAX_SG_COUNT,
+	};
+	struct ubiblock *dev;
+	struct gendisk *gd;
+	u64 disk_capacity;
+	int ret;
+
+	ret = calc_disk_capacity(vi, &disk_capacity);
+	if (ret) {
+		return ret;
+	}
+
+	/* Check that the volume isn't already handled */
+	mutex_lock(&devices_mutex);
+	if (find_dev_nolock(vi->ubi_num, vi->vol_id)) {
+		ret = -EEXIST;
+		goto out_unlock;
+	}
+
+	dev = kzalloc_obj(struct ubiblock);
+	if (!dev) {
+		ret = -ENOMEM;
+		goto out_unlock;
+	}
+
+	mutex_init(&dev->dev_mutex);
+
+	dev->ubi_num = vi->ubi_num;
+	dev->vol_id = vi->vol_id;
+	dev->leb_size = vi->usable_leb_size;
+
+	dev->tag_set.ops = &ubiblock_mq_ops;
+	dev->tag_set.queue_depth = 64;
+	dev->tag_set.numa_node = NUMA_NO_NODE;
+	dev->tag_set.flags = BLK_MQ_F_BLOCKING;
+	dev->tag_set.cmd_size = sizeof(struct ubiblock_pdu);
+	dev->tag_set.driver_data = dev;
+	dev->tag_set.nr_hw_queues = 1;
+
+	ret = blk_mq_alloc_tag_set(&dev->tag_set);
+	if (ret) {
+		pr_err("ubiblock%d_%d: blk_mq_alloc_tag_set failed\n",
+			dev->ubi_num, dev->vol_id);
+		goto out_free_dev;
+	}
+
+
+	/* Initialize the gendisk of this ubiblock device */
+	gd = blk_mq_alloc_disk(&dev->tag_set, &lim, dev);
+	if (IS_ERR(gd)) {
+		ret = PTR_ERR(gd);
+		goto out_free_tags;
+	}
+
+	gd->fops = &ubiblock_ops;
+	gd->major = ubiblock_major;
+	gd->minors = 1;
+	gd->first_minor = idr_alloc(&ubiblock_minor_idr, dev, 0, 0, GFP_KERNEL);
+	if (gd->first_minor < 0) {
+		pr_err("ubiblock%d_%d: block: dynamic minor allocation failed\n",
+			dev->ubi_num, dev->vol_id);
+		ret = -ENODEV;
+		goto out_cleanup_disk;
+	}
+	gd->flags |= GENHD_FL_NO_PART;
+	gd->private_data = dev;
+	sprintf(gd->disk_name, "ubiblock%d_%d", dev->ubi_num, dev->vol_id);
+	set_capacity(gd, disk_capacity);
+	dev->gd = gd;
+
+	dev->rq = gd->queue;
+
+	list_add_tail(&dev->list, &ubiblock_devices);
+
+	/* Must be the last step: anyone can call file ops from now on */
+	ret = device_add_disk(vi->dev, dev->gd, NULL);
+	if (ret)
+		goto out_remove_minor;
+
+	dev_info(disk_to_dev(dev->gd), "created from ubi%d:%d(%s)",
+		 dev->ubi_num, dev->vol_id, vi->name);
+	mutex_unlock(&devices_mutex);
+	return 0;
+
+out_remove_minor:
+	list_del(&dev->list);
+	idr_remove(&ubiblock_minor_idr, gd->first_minor);
+out_cleanup_disk:
+	put_disk(gd);
+out_free_tags:
+	blk_mq_free_tag_set(&dev->tag_set);
+out_free_dev:
+	kfree(dev);
+out_unlock:
+	mutex_unlock(&devices_mutex);
+
+	return ret;
+}
+
+static void ubiblock_cleanup(struct ubiblock *dev)
+{
+	int id = dev->gd->first_minor;
+
+	/* Stop new requests to arrive */
+	del_gendisk(dev->gd);
+	/* Finally destroy the blk queue */
+	dev_info(disk_to_dev(dev->gd), "released");
+	put_disk(dev->gd);
+	blk_mq_free_tag_set(&dev->tag_set);
+	idr_remove(&ubiblock_minor_idr, id);
+}
+
+int ubiblock_remove(struct ubi_volume_info *vi)
+{
+	struct ubiblock *dev;
+	int ret;
+
+	mutex_lock(&devices_mutex);
+	dev = find_dev_nolock(vi->ubi_num, vi->vol_id);
+	if (!dev) {
+		ret = -ENODEV;
+		goto out_unlock;
+	}
+
+	/* Found a device, let's lock it so we can check if it's busy */
+	mutex_lock(&dev->dev_mutex);
+	if (dev->refcnt > 0) {
+		ret = -EBUSY;
+		goto out_unlock_dev;
+	}
+
+	/* Remove from device list */
+	list_del(&dev->list);
+	ubiblock_cleanup(dev);
+	mutex_unlock(&dev->dev_mutex);
+	mutex_unlock(&devices_mutex);
+
+	kfree(dev);
+	return 0;
+
+out_unlock_dev:
+	mutex_unlock(&dev->dev_mutex);
+out_unlock:
+	mutex_unlock(&devices_mutex);
+	return ret;
+}
+
+static int ubiblock_resize(struct ubi_volume_info *vi)
+{
+	struct ubiblock *dev;
+	u64 disk_capacity;
+	int ret;
+
+	/*
+	 * Need to lock the device list until we stop using the device,
+	 * otherwise the device struct might get released in
+	 * 'ubiblock_remove()'.
+	 */
+	mutex_lock(&devices_mutex);
+	dev = find_dev_nolock(vi->ubi_num, vi->vol_id);
+	if (!dev) {
+		mutex_unlock(&devices_mutex);
+		return -ENODEV;
+	}
+
+	ret = calc_disk_capacity(vi, &disk_capacity);
+	if (ret) {
+		mutex_unlock(&devices_mutex);
+		if (ret == -EFBIG) {
+			dev_warn(disk_to_dev(dev->gd),
+				 "the volume is too big (%d LEBs), cannot resize",
+				 vi->size);
+		}
+		return ret;
+	}
+
+	mutex_lock(&dev->dev_mutex);
+
+	if (get_capacity(dev->gd) != disk_capacity) {
+		set_capacity(dev->gd, disk_capacity);
+		dev_info(disk_to_dev(dev->gd), "resized to %lld bytes",
+			 vi->used_bytes);
+	}
+	mutex_unlock(&dev->dev_mutex);
+	mutex_unlock(&devices_mutex);
+	return 0;
+}
+
+static bool
+match_volume_desc(struct ubi_volume_info *vi, const char *name, int ubi_num, int vol_id)
+{
+	int err, len, cur_ubi_num, cur_vol_id;
+
+	if (ubi_num == -1) {
+		/* No ubi num, name must be a vol device path */
+		err = ubi_get_num_by_path(name, &cur_ubi_num, &cur_vol_id);
+		if (err || vi->ubi_num != cur_ubi_num || vi->vol_id != cur_vol_id)
+			return false;
+
+		return true;
+	}
+
+	if (vol_id == -1) {
+		/* Got ubi_num, but no vol_id, name must be volume name */
+		if (vi->ubi_num != ubi_num)
+			return false;
+
+		len = strnlen(name, UBI_VOL_NAME_MAX + 1);
+		if (len < 1 || vi->name_len != len)
+			return false;
+
+		if (strcmp(name, vi->name))
+			return false;
+
+		return true;
+	}
+
+	if (vi->ubi_num != ubi_num)
+		return false;
+
+	if (vi->vol_id != vol_id)
+		return false;
+
+	return true;
+}
+
+static void
+ubiblock_create_from_param(struct ubi_volume_info *vi)
+{
+	int i, ret = 0;
+	struct ubiblock_param *p;
+
+	/*
+	 * Iterate over ubiblock cmdline parameters. If a parameter matches the
+	 * newly added volume create the ubiblock device for it.
+	 */
+	for (i = 0; i < ubiblock_devs; i++) {
+		p = &ubiblock_param[i];
+
+		if (!match_volume_desc(vi, p->name, p->ubi_num, p->vol_id))
+			continue;
+
+		ret = ubiblock_create(vi);
+		if (ret) {
+			pr_err(
+			       "UBI: block: can't add '%s' volume on ubi%d_%d, err=%d\n",
+			       vi->name, p->ubi_num, p->vol_id, ret);
+		}
+		break;
+	}
+}
+
+static int ubiblock_notify(struct notifier_block *nb,
+			 unsigned long notification_type, void *ns_ptr)
+{
+	struct ubi_notification *nt = ns_ptr;
+
+	switch (notification_type) {
+	case UBI_VOLUME_ADDED:
+		ubiblock_create_from_param(&nt->vi);
+		break;
+	case UBI_VOLUME_REMOVED:
+		ubiblock_remove(&nt->vi);
+		break;
+	case UBI_VOLUME_RESIZED:
+		ubiblock_resize(&nt->vi);
+		break;
+	case UBI_VOLUME_UPDATED:
+		/*
+		 * If the volume is static, a content update might mean the
+		 * size (i.e. used_bytes) was also changed.
+		 */
+		if (nt->vi.vol_type == UBI_STATIC_VOLUME)
+			ubiblock_resize(&nt->vi);
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block ubiblock_notifier = {
+	.notifier_call = ubiblock_notify,
+};
+
+static void ubiblock_remove_all(void)
+{
+	struct ubiblock *next;
+	struct ubiblock *dev;
+
+	mutex_lock(&devices_mutex);
+	list_for_each_entry_safe(dev, next, &ubiblock_devices, list) {
+		/* The module is being forcefully removed */
+		WARN_ON(dev->desc);
+		/* Remove from device list */
+		list_del(&dev->list);
+		ubiblock_cleanup(dev);
+		kfree(dev);
+	}
+	mutex_unlock(&devices_mutex);
+}
+
+int __init ubiblock_init(void)
+{
+	int ret;
+
+	ubiblock_major = register_blkdev(0, "ubiblock");
+	if (ubiblock_major < 0)
+		return ubiblock_major;
+
+	ret = ubi_register_volume_notifier(&ubiblock_notifier, 0);
+	if (ret)
+		goto err_unreg;
+	return 0;
+
+err_unreg:
+	unregister_blkdev(ubiblock_major, "ubiblock");
+	ubiblock_remove_all();
+	return ret;
+}
+
+void ubiblock_exit(void)
+{
+	ubi_unregister_volume_notifier(&ubiblock_notifier);
+	ubiblock_remove_all();
+	unregister_blkdev(ubiblock_major, "ubiblock");
+}