Merge branch 'for-linus-v3.20' of git://git.infradead.org/linux-ubifs

Pull UBI and UBIFS updates from Richard Weinberger:
 - cleanups and bug fixes all over UBI and UBIFS
 - block-mq support for UBI Block
 - UBI volumes can now be renamed while they are in use
 - security.* XATTR support for UBIFS
 - a maintainer update

* 'for-linus-v3.20' of git://git.infradead.org/linux-ubifs:
  UBI: block: Fix checking for NULL instead of IS_ERR()
  UBI: block: Continue creating ubiblocks after an initialization error
  UBIFS: return -EINVAL if log head is empty
  UBI: Block: Explain usage of blk_rq_map_sg()
  UBI: fix soft lockup in ubi_check_volume()
  UBI: Fastmap: Care about the protection queue
  UBIFS: add a couple of extra asserts
  UBI: do propagate positive error codes up
  UBI: clean-up printing helpers
  UBI: extend UBI layer debug/messaging capabilities - cosmetics
  UBIFS: add ubifs_err() to print error reason
  UBIFS: Add security.* XATTR support for the UBIFS
  UBIFS: Add xattr support for symlinks
  UBI: Block: Add blk-mq support
  UBI: Add initial support for scatter gather
  UBI: rename_volumes: Use UBI_METAONLY
  UBI: Implement UBI_METAONLY
  Add myself as UBI co-maintainer

11 files changed, 319 insertions, 173 deletions

diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c
index 6b6bce28bd63..db2c05b6fe7f 100644
--- a/drivers/mtd/ubi/block.c
+++ b/drivers/mtd/ubi/block.c
@@ -42,11 +42,12 @@
 #include <linux/list.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
-#include <linux/vmalloc.h>
 #include <linux/mtd/ubi.h>
 #include <linux/workqueue.h>
 #include <linux/blkdev.h>
+#include <linux/blk-mq.h>
 #include <linux/hdreg.h>
+#include <linux/scatterlist.h>
 #include <asm/div64.h>
 
 #include "ubi-media.h"
@@ -67,6 +68,11 @@ struct ubiblock_param {
 	char name[UBIBLOCK_PARAM_LEN+1];
 };
 
+struct ubiblock_pdu {
+	struct work_struct work;
+	struct ubi_sgl usgl;
+};
+
 /* Numbers of elements set in the @ubiblock_param array */
 static int ubiblock_devs __initdata;
 
@@ -84,11 +90,10 @@ struct ubiblock {
 	struct request_queue *rq;
 
 	struct workqueue_struct *wq;
-	struct work_struct work;
 
 	struct mutex dev_mutex;
-	spinlock_t queue_lock;
 	struct list_head list;
+	struct blk_mq_tag_set tag_set;
 };
 
 /* Linked list of all ubiblock instances */
@@ -181,31 +186,20 @@ static struct ubiblock *find_dev_nolock(int ubi_num, int vol_id)
 	return NULL;
 }
 
-static int ubiblock_read_to_buf(struct ubiblock *dev, char *buffer,
-				int leb, int offset, int len)
+static int ubiblock_read(struct ubiblock_pdu *pdu)
 {
-	int ret;
-
-	ret = ubi_read(dev->desc, leb, buffer, offset, len);
-	if (ret) {
-		dev_err(disk_to_dev(dev->gd), "%d while reading from LEB %d (offset %d, length %d)",
-			ret, leb, offset, len);
-		return ret;
-	}
-	return 0;
-}
+	int ret, leb, offset, bytes_left, to_read;
+	u64 pos;
+	struct request *req = blk_mq_rq_from_pdu(pdu);
+	struct ubiblock *dev = req->q->queuedata;
 
-static int ubiblock_read(struct ubiblock *dev, char *buffer,
-			 sector_t sec, int len)
-{
-	int ret, leb, offset;
-	int bytes_left = len;
-	int to_read = len;
-	u64 pos = sec << 9;
+	to_read = blk_rq_bytes(req);
+	pos = blk_rq_pos(req) << 9;
 
 	/* Get LEB:offset address to read from */
 	offset = do_div(pos, dev->leb_size);
 	leb = pos;
+	bytes_left = to_read;
 
 	while (bytes_left) {
 		/*
@@ -215,11 +209,10 @@ static int ubiblock_read(struct ubiblock *dev, char *buffer,
 		if (offset + to_read > dev->leb_size)
 			to_read = dev->leb_size - offset;
 
-		ret = ubiblock_read_to_buf(dev, buffer, leb, offset, to_read);
-		if (ret)
+		ret = ubi_read_sg(dev->desc, leb, &pdu->usgl, offset, to_read);
+		if (ret < 0)
 			return ret;
 
-		buffer += to_read;
 		bytes_left -= to_read;
 		to_read = bytes_left;
 		leb += 1;
@@ -228,79 +221,6 @@ static int ubiblock_read(struct ubiblock *dev, char *buffer,
 	return 0;
 }
 
-static int do_ubiblock_request(struct ubiblock *dev, struct request *req)
-{
-	int len, ret;
-	sector_t sec;
-
-	if (req->cmd_type != REQ_TYPE_FS)
-		return -EIO;
-
-	if (blk_rq_pos(req) + blk_rq_cur_sectors(req) >
-	    get_capacity(req->rq_disk))
-		return -EIO;
-
-	if (rq_data_dir(req) != READ)
-		return -ENOSYS; /* Write not implemented */
-
-	sec = blk_rq_pos(req);
-	len = blk_rq_cur_bytes(req);
-
-	/*
-	 * Let's prevent the device from being removed while we're doing I/O
-	 * work. Notice that this means we serialize all the I/O operations,
-	 * but it's probably of no impact given the NAND core serializes
-	 * flash access anyway.
-	 */
-	mutex_lock(&dev->dev_mutex);
-	ret = ubiblock_read(dev, bio_data(req->bio), sec, len);
-	mutex_unlock(&dev->dev_mutex);
-
-	return ret;
-}
-
-static void ubiblock_do_work(struct work_struct *work)
-{
-	struct ubiblock *dev =
-		container_of(work, struct ubiblock, work);
-	struct request_queue *rq = dev->rq;
-	struct request *req;
-	int res;
-
-	spin_lock_irq(rq->queue_lock);
-
-	req = blk_fetch_request(rq);
-	while (req) {
-
-		spin_unlock_irq(rq->queue_lock);
-		res = do_ubiblock_request(dev, req);
-		spin_lock_irq(rq->queue_lock);
-
-		/*
-		 * If we're done with this request,
-		 * we need to fetch a new one
-		 */
-		if (!__blk_end_request_cur(req, res))
-			req = blk_fetch_request(rq);
-	}
-
-	spin_unlock_irq(rq->queue_lock);
-}
-
-static void ubiblock_request(struct request_queue *rq)
-{
-	struct ubiblock *dev;
-	struct request *req;
-
-	dev = rq->queuedata;
-
-	if (!dev)
-		while ((req = blk_fetch_request(rq)) != NULL)
-			__blk_end_request_all(req, -ENODEV);
-	else
-		queue_work(dev->wq, &dev->work);
-}
-
 static int ubiblock_open(struct block_device *bdev, fmode_t mode)
 {
 	struct ubiblock *dev = bdev->bd_disk->private_data;
@@ -374,6 +294,63 @@ static const struct block_device_operations ubiblock_ops = {
 	.getgeo	= ubiblock_getgeo,
 };
 
+static void ubiblock_do_work(struct work_struct *work)
+{
+	int ret;
+	struct ubiblock_pdu *pdu = container_of(work, struct ubiblock_pdu, work);
+	struct request *req = blk_mq_rq_from_pdu(pdu);
+
+	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.
+	 */
+	blk_rq_map_sg(req->q, req, pdu->usgl.sg);
+
+	ret = ubiblock_read(pdu);
+	blk_mq_end_request(req, ret);
+}
+
+static int ubiblock_queue_rq(struct blk_mq_hw_ctx *hctx,
+			     const struct blk_mq_queue_data *bd)
+{
+	struct request *req = bd->rq;
+	struct ubiblock *dev = hctx->queue->queuedata;
+	struct ubiblock_pdu *pdu = blk_mq_rq_to_pdu(req);
+
+	if (req->cmd_type != REQ_TYPE_FS)
+		return BLK_MQ_RQ_QUEUE_ERROR;
+
+	if (rq_data_dir(req) != READ)
+		return BLK_MQ_RQ_QUEUE_ERROR; /* Write not implemented */
+
+	ubi_sgl_init(&pdu->usgl);
+	queue_work(dev->wq, &pdu->work);
+
+	return BLK_MQ_RQ_QUEUE_OK;
+}
+
+static int ubiblock_init_request(void *data, struct request *req,
+				 unsigned int hctx_idx,
+				 unsigned int request_idx,
+				 unsigned int numa_node)
+{
+	struct ubiblock_pdu *pdu = blk_mq_rq_to_pdu(req);
+
+	sg_init_table(pdu->usgl.sg, UBI_MAX_SG_COUNT);
+	INIT_WORK(&pdu->work, ubiblock_do_work);
+
+	return 0;
+}
+
+static struct blk_mq_ops ubiblock_mq_ops = {
+	.queue_rq       = ubiblock_queue_rq,
+	.init_request	= ubiblock_init_request,
+	.map_queue      = blk_mq_map_queue,
+};
+
 int ubiblock_create(struct ubi_volume_info *vi)
 {
 	struct ubiblock *dev;
@@ -417,14 +394,28 @@ int ubiblock_create(struct ubi_volume_info *vi)
 	set_capacity(gd, disk_capacity);
 	dev->gd = gd;
 
-	spin_lock_init(&dev->queue_lock);
-	dev->rq = blk_init_queue(ubiblock_request, &dev->queue_lock);
-	if (!dev->rq) {
-		dev_err(disk_to_dev(gd), "blk_init_queue failed");
-		ret = -ENODEV;
+	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_SHOULD_MERGE;
+	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) {
+		dev_err(disk_to_dev(dev->gd), "blk_mq_alloc_tag_set failed");
 		goto out_put_disk;
 	}
 
+	dev->rq = blk_mq_init_queue(&dev->tag_set);
+	if (IS_ERR(dev->rq)) {
+		dev_err(disk_to_dev(gd), "blk_mq_init_queue failed");
+		ret = PTR_ERR(dev->rq);
+		goto out_free_tags;
+	}
+	blk_queue_max_segments(dev->rq, UBI_MAX_SG_COUNT);
+
 	dev->rq->queuedata = dev;
 	dev->gd->queue = dev->rq;
 
@@ -437,7 +428,6 @@ int ubiblock_create(struct ubi_volume_info *vi)
 		ret = -ENOMEM;
 		goto out_free_queue;
 	}
-	INIT_WORK(&dev->work, ubiblock_do_work);
 
 	mutex_lock(&devices_mutex);
 	list_add_tail(&dev->list, &ubiblock_devices);
@@ -451,6 +441,8 @@ int ubiblock_create(struct ubi_volume_info *vi)
 
 out_free_queue:
 	blk_cleanup_queue(dev->rq);
+out_free_tags:
+	blk_mq_free_tag_set(&dev->tag_set);
 out_put_disk:
 	put_disk(dev->gd);
 out_free_dev:
@@ -461,8 +453,13 @@ out_free_dev:
 
 static void ubiblock_cleanup(struct ubiblock *dev)
 {
+	/* Stop new requests to arrive */
 	del_gendisk(dev->gd);
+	/* Flush pending work */
+	destroy_workqueue(dev->wq);
+	/* Finally destroy the blk queue */
 	blk_cleanup_queue(dev->rq);
+	blk_mq_free_tag_set(&dev->tag_set);
 	dev_info(disk_to_dev(dev->gd), "released");
 	put_disk(dev->gd);
 }
@@ -490,9 +487,6 @@ int ubiblock_remove(struct ubi_volume_info *vi)
 	list_del(&dev->list);
 	mutex_unlock(&devices_mutex);
 
-	/* Flush pending work and stop this workqueue */
-	destroy_workqueue(dev->wq);
-
 	ubiblock_cleanup(dev);
 	mutex_unlock(&dev->dev_mutex);
 	kfree(dev);
@@ -583,22 +577,28 @@ open_volume_desc(const char *name, int ubi_num, int vol_id)
 		return ubi_open_volume(ubi_num, vol_id, UBI_READONLY);
 }
 
-static int __init ubiblock_create_from_param(void)
+static void __init ubiblock_create_from_param(void)
 {
-	int i, ret;
+	int i, ret = 0;
 	struct ubiblock_param *p;
 	struct ubi_volume_desc *desc;
 	struct ubi_volume_info vi;
 
+	/*
+	 * If there is an error creating one of the ubiblocks, continue on to
+	 * create the following ubiblocks. This helps in a circumstance where
+	 * the kernel command-line specifies multiple block devices and some
+	 * may be broken, but we still want the working ones to come up.
+	 */
 	for (i = 0; i < ubiblock_devs; i++) {
 		p = &ubiblock_param[i];
 
 		desc = open_volume_desc(p->name, p->ubi_num, p->vol_id);
 		if (IS_ERR(desc)) {
-			pr_err("UBI: block: can't open volume, err=%ld\n",
-			       PTR_ERR(desc));
-			ret = PTR_ERR(desc);
-			break;
+			pr_err(
+			       "UBI: block: can't open volume on ubi%d_%d, err=%ld",
+			       p->ubi_num, p->vol_id, PTR_ERR(desc));
+			continue;
 		}
 
 		ubi_get_volume_info(desc, &vi);
@@ -606,12 +606,12 @@ static int __init ubiblock_create_from_param(void)
 
 		ret = ubiblock_create(&vi);
 		if (ret) {
-			pr_err("UBI: block: can't add '%s' volume, err=%d\n",
-			       vi.name, ret);
-			break;
+			pr_err(
+			       "UBI: block: can't add '%s' volume on ubi%d_%d, err=%d",
+			       vi.name, p->ubi_num, p->vol_id, ret);
+			continue;
 		}
 	}
-	return ret;
 }
 
 static void ubiblock_remove_all(void)
@@ -620,8 +620,6 @@ static void ubiblock_remove_all(void)
 	struct ubiblock *dev;
 
 	list_for_each_entry_safe(dev, next, &ubiblock_devices, list) {
-		/* Flush pending work and stop workqueue */
-		destroy_workqueue(dev->wq);
 		/* The module is being forcefully removed */
 		WARN_ON(dev->desc);
 		/* Remove from device list */
@@ -639,10 +637,12 @@ int __init ubiblock_init(void)
 	if (ubiblock_major < 0)
 		return ubiblock_major;
 
-	/* Attach block devices from 'block=' module param */
-	ret = ubiblock_create_from_param();
-	if (ret)
-		goto err_remove;
+	/*
+	 * Attach block devices from 'block=' module param.
+	 * Even if one block device in the param list fails to come up,
+	 * still allow the module to load and leave any others up.
+	 */
+	ubiblock_create_from_param();
 
 	/*
 	 * Block devices are only created upon user requests, so we ignore
@@ -655,7 +655,6 @@ int __init ubiblock_init(void)
 
 err_unreg:
 	unregister_blkdev(ubiblock_major, "ubiblock");
-err_remove:
 	ubiblock_remove_all();
 	return ret;
 }
diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 3405be46ebe9..ba01a8d22d28 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -923,7 +923,7 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
 
 		/* Make sure ubi_num is not busy */
 		if (ubi_devices[ubi_num]) {
-			ubi_err(ubi, "ubi%d already exists", ubi_num);
+			ubi_err(ubi, "already exists");
 			return -EEXIST;
 		}
 	}
@@ -973,7 +973,7 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
 	mutex_init(&ubi->fm_mutex);
 	init_rwsem(&ubi->fm_sem);
 
-	ubi_msg(ubi, "attaching mtd%d to ubi%d", mtd->index, ubi_num);
+	ubi_msg(ubi, "attaching mtd%d", mtd->index);
 
 	err = io_init(ubi, max_beb_per1024);
 	if (err)
@@ -1428,7 +1428,7 @@ static int __init ubi_mtd_param_parse(const char *val, struct kernel_param *kp)
 	}
 
 	if (len == 0) {
-		pr_err("UBI warning: empty 'mtd=' parameter - ignored\n");
+		pr_warn("UBI warning: empty 'mtd=' parameter - ignored\n");
 		return 0;
 	}
 
diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c
index 3410ea8109f8..d647e504f9b1 100644
--- a/drivers/mtd/ubi/cdev.c
+++ b/drivers/mtd/ubi/cdev.c
@@ -48,26 +48,25 @@
 
 /**
  * get_exclusive - get exclusive access to an UBI volume.
- * @ubi: UBI device description object
  * @desc: volume descriptor
  *
  * This function changes UBI volume open mode to "exclusive". Returns previous
  * mode value (positive integer) in case of success and a negative error code
  * in case of failure.
  */
-static int get_exclusive(struct ubi_device *ubi, struct ubi_volume_desc *desc)
+static int get_exclusive(struct ubi_volume_desc *desc)
 {
 	int users, err;
 	struct ubi_volume *vol = desc->vol;
 
 	spin_lock(&vol->ubi->volumes_lock);
-	users = vol->readers + vol->writers + vol->exclusive;
+	users = vol->readers + vol->writers + vol->exclusive + vol->metaonly;
 	ubi_assert(users > 0);
 	if (users > 1) {
-		ubi_err(ubi, "%d users for volume %d", users, vol->vol_id);
+		ubi_err(vol->ubi, "%d users for volume %d", users, vol->vol_id);
 		err = -EBUSY;
 	} else {
-		vol->readers = vol->writers = 0;
+		vol->readers = vol->writers = vol->metaonly = 0;
 		vol->exclusive = 1;
 		err = desc->mode;
 		desc->mode = UBI_EXCLUSIVE;
@@ -87,13 +86,15 @@ static void revoke_exclusive(struct ubi_volume_desc *desc, int mode)
 	struct ubi_volume *vol = desc->vol;
 
 	spin_lock(&vol->ubi->volumes_lock);
-	ubi_assert(vol->readers == 0 && vol->writers == 0);
+	ubi_assert(vol->readers == 0 && vol->writers == 0 && vol->metaonly == 0);
 	ubi_assert(vol->exclusive == 1 && desc->mode == UBI_EXCLUSIVE);
 	vol->exclusive = 0;
 	if (mode == UBI_READONLY)
 		vol->readers = 1;
 	else if (mode == UBI_READWRITE)
 		vol->writers = 1;
+	else if (mode == UBI_METAONLY)
+		vol->metaonly = 1;
 	else
 		vol->exclusive = 1;
 	spin_unlock(&vol->ubi->volumes_lock);
@@ -421,7 +422,7 @@ static long vol_cdev_ioctl(struct file *file, unsigned int cmd,
 			break;
 		}
 
-		err = get_exclusive(ubi, desc);
+		err = get_exclusive(desc);
 		if (err < 0)
 			break;
 
@@ -457,7 +458,7 @@ static long vol_cdev_ioctl(struct file *file, unsigned int cmd,
 		    req.bytes < 0 || req.lnum >= vol->usable_leb_size)
 			break;
 
-		err = get_exclusive(ubi, desc);
+		err = get_exclusive(desc);
 		if (err < 0)
 			break;
 
@@ -734,7 +735,7 @@ static int rename_volumes(struct ubi_device *ubi,
 			goto out_free;
 		}
 
-		re->desc = ubi_open_volume(ubi->ubi_num, vol_id, UBI_READWRITE);
+		re->desc = ubi_open_volume(ubi->ubi_num, vol_id, UBI_METAONLY);
 		if (IS_ERR(re->desc)) {
 			err = PTR_ERR(re->desc);
 			ubi_err(ubi, "cannot open volume %d, error %d",
diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
index a40020cf0923..da4c79259f67 100644
--- a/drivers/mtd/ubi/eba.c
+++ b/drivers/mtd/ubi/eba.c
@@ -426,6 +426,7 @@ retry:
 						 pnum, vol_id, lnum);
 					err = -EBADMSG;
 				} else
+					err = -EINVAL;
 					ubi_ro_mode(ubi);
 			}
 			goto out_free;
@@ -480,6 +481,61 @@ out_unlock:
 }
 
 /**
+ * ubi_eba_read_leb_sg - read data into a scatter gather list.
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ * @lnum: logical eraseblock number
+ * @sgl: UBI scatter gather list to store the read data
+ * @offset: offset from where to read
+ * @len: how many bytes to read
+ * @check: data CRC check flag
+ *
+ * This function works exactly like ubi_eba_read_leb(). But instead of
+ * storing the read data into a buffer it writes to an UBI scatter gather
+ * list.
+ */
+int ubi_eba_read_leb_sg(struct ubi_device *ubi, struct ubi_volume *vol,
+			struct ubi_sgl *sgl, int lnum, int offset, int len,
+			int check)
+{
+	int to_read;
+	int ret;
+	struct scatterlist *sg;
+
+	for (;;) {
+		ubi_assert(sgl->list_pos < UBI_MAX_SG_COUNT);
+		sg = &sgl->sg[sgl->list_pos];
+		if (len < sg->length - sgl->page_pos)
+			to_read = len;
+		else
+			to_read = sg->length - sgl->page_pos;
+
+		ret = ubi_eba_read_leb(ubi, vol, lnum,
+				       sg_virt(sg) + sgl->page_pos, offset,
+				       to_read, check);
+		if (ret < 0)
+			return ret;
+
+		offset += to_read;
+		len -= to_read;
+		if (!len) {
+			sgl->page_pos += to_read;
+			if (sgl->page_pos == sg->length) {
+				sgl->list_pos++;
+				sgl->page_pos = 0;
+			}
+
+			break;
+		}
+
+		sgl->list_pos++;
+		sgl->page_pos = 0;
+	}
+
+	return ret;
+}
+
+/**
  * recover_peb - recover from write failure.
  * @ubi: UBI device description object
  * @pnum: the physical eraseblock to recover
diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c
index b56672bf3294..db3defdfc3c0 100644
--- a/drivers/mtd/ubi/fastmap.c
+++ b/drivers/mtd/ubi/fastmap.c
@@ -1196,6 +1196,19 @@ static int ubi_write_fastmap(struct ubi_device *ubi,
 		fm_pos += sizeof(*fec);
 		ubi_assert(fm_pos <= ubi->fm_size);
 	}
+
+	for (i = 0; i < UBI_PROT_QUEUE_LEN; i++) {
+		list_for_each_entry(wl_e, &ubi->pq[i], u.list) {
+			fec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+
+			fec->pnum = cpu_to_be32(wl_e->pnum);
+			fec->ec = cpu_to_be32(wl_e->ec);
+
+			used_peb_count++;
+			fm_pos += sizeof(*fec);
+			ubi_assert(fm_pos <= ubi->fm_size);
+		}
+	}
 	fmh->used_peb_count = cpu_to_be32(used_peb_count);
 
 	for (node = rb_first(&ubi->scrub); node; node = rb_next(node)) {
diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
index 396aaa543362..ed0bcb35472f 100644
--- a/drivers/mtd/ubi/io.c
+++ b/drivers/mtd/ubi/io.c
@@ -1419,8 +1419,7 @@ int ubi_self_check_all_ff(struct ubi_device *ubi, int pnum, int offset, int len)
 
 fail:
 	ubi_err(ubi, "self-check failed for PEB %d", pnum);
-	ubi_msg(ubi, "hex dump of the %d-%d region",
-		 offset, offset + len);
+	ubi_msg(ubi, "hex dump of the %d-%d region", offset, offset + len);
 	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1, buf, len, 1);
 	err = -EINVAL;
 error:
diff --git a/drivers/mtd/ubi/kapi.c b/drivers/mtd/ubi/kapi.c
index f3bab669f6bb..478e00cf2d9e 100644
--- a/drivers/mtd/ubi/kapi.c
+++ b/drivers/mtd/ubi/kapi.c
@@ -137,7 +137,7 @@ struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode)
 		return ERR_PTR(-EINVAL);
 
 	if (mode != UBI_READONLY && mode != UBI_READWRITE &&
-	    mode != UBI_EXCLUSIVE)
+	    mode != UBI_EXCLUSIVE && mode != UBI_METAONLY)
 		return ERR_PTR(-EINVAL);
 
 	/*
@@ -182,10 +182,17 @@ struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode)
 		break;
 
 	case UBI_EXCLUSIVE:
-		if (vol->exclusive || vol->writers || vol->readers)
+		if (vol->exclusive || vol->writers || vol->readers ||
+		    vol->metaonly)
 			goto out_unlock;
 		vol->exclusive = 1;
 		break;
+
+	case UBI_METAONLY:
+		if (vol->metaonly || vol->exclusive)
+			goto out_unlock;
+		vol->metaonly = 1;
+		break;
 	}
 	get_device(&vol->dev);
 	vol->ref_count += 1;
@@ -343,6 +350,10 @@ void ubi_close_volume(struct ubi_volume_desc *desc)
 		break;
 	case UBI_EXCLUSIVE:
 		vol->exclusive = 0;
+		break;
+	case UBI_METAONLY:
+		vol->metaonly = 0;
+		break;
 	}
 	vol->ref_count -= 1;
 	spin_unlock(&ubi->volumes_lock);
@@ -355,6 +366,43 @@ void ubi_close_volume(struct ubi_volume_desc *desc)
 EXPORT_SYMBOL_GPL(ubi_close_volume);
 
 /**
+ * leb_read_sanity_check - does sanity checks on read requests.
+ * @desc: volume descriptor
+ * @lnum: logical eraseblock number to read from
+ * @offset: offset within the logical eraseblock to read from
+ * @len: how many bytes to read
+ *
+ * This function is used by ubi_leb_read() and ubi_leb_read_sg()
+ * to perform sanity checks.
+ */
+static int leb_read_sanity_check(struct ubi_volume_desc *desc, int lnum,
+				 int offset, int len)
+{
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+	int vol_id = vol->vol_id;
+
+	if (vol_id < 0 || vol_id >= ubi->vtbl_slots || lnum < 0 ||
+	    lnum >= vol->used_ebs || offset < 0 || len < 0 ||
+	    offset + len > vol->usable_leb_size)
+		return -EINVAL;
+
+	if (vol->vol_type == UBI_STATIC_VOLUME) {
+		if (vol->used_ebs == 0)
+			/* Empty static UBI volume */
+			return 0;
+		if (lnum == vol->used_ebs - 1 &&
+		    offset + len > vol->last_eb_bytes)
+			return -EINVAL;
+	}
+
+	if (vol->upd_marker)
+		return -EBADF;
+
+	return 0;
+}
+
+/**
  * ubi_leb_read - read data.
  * @desc: volume descriptor
  * @lnum: logical eraseblock number to read from
@@ -390,22 +438,10 @@ int ubi_leb_read(struct ubi_volume_desc *desc, int lnum, char *buf, int offset,
 
 	dbg_gen("read %d bytes from LEB %d:%d:%d", len, vol_id, lnum, offset);
 
-	if (vol_id < 0 || vol_id >= ubi->vtbl_slots || lnum < 0 ||
-	    lnum >= vol->used_ebs || offset < 0 || len < 0 ||
-	    offset + len > vol->usable_leb_size)
-		return -EINVAL;
-
-	if (vol->vol_type == UBI_STATIC_VOLUME) {
-		if (vol->used_ebs == 0)
-			/* Empty static UBI volume */
-			return 0;
-		if (lnum == vol->used_ebs - 1 &&
-		    offset + len > vol->last_eb_bytes)
-			return -EINVAL;
-	}
+	err = leb_read_sanity_check(desc, lnum, offset, len);
+	if (err < 0)
+		return err;
 
-	if (vol->upd_marker)
-		return -EBADF;
 	if (len == 0)
 		return 0;
 
@@ -419,6 +455,46 @@ int ubi_leb_read(struct ubi_volume_desc *desc, int lnum, char *buf, int offset,
 }
 EXPORT_SYMBOL_GPL(ubi_leb_read);
 
+
+/**
+ * ubi_leb_read_sg - read data into a scatter gather list.
+ * @desc: volume descriptor
+ * @lnum: logical eraseblock number to read from
+ * @buf: buffer where to store the read data
+ * @offset: offset within the logical eraseblock to read from
+ * @len: how many bytes to read
+ * @check: whether UBI has to check the read data's CRC or not.
+ *
+ * This function works exactly like ubi_leb_read_sg(). But instead of
+ * storing the read data into a buffer it writes to an UBI scatter gather
+ * list.
+ */
+int ubi_leb_read_sg(struct ubi_volume_desc *desc, int lnum, struct ubi_sgl *sgl,
+		    int offset, int len, int check)
+{
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+	int err, vol_id = vol->vol_id;
+
+	dbg_gen("read %d bytes from LEB %d:%d:%d", len, vol_id, lnum, offset);
+
+	err = leb_read_sanity_check(desc, lnum, offset, len);
+	if (err < 0)
+		return err;
+
+	if (len == 0)
+		return 0;
+
+	err = ubi_eba_read_leb_sg(ubi, vol, sgl, lnum, offset, len, check);
+	if (err && mtd_is_eccerr(err) && vol->vol_type == UBI_STATIC_VOLUME) {
+		ubi_warn(ubi, "mark volume %d as corrupted", vol_id);
+		vol->corrupted = 1;
+	}
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(ubi_leb_read_sg);
+
 /**
  * ubi_leb_write - write data.
  * @desc: volume descriptor
diff --git a/drivers/mtd/ubi/misc.c b/drivers/mtd/ubi/misc.c
index dbda77e556cb..2a45ac210b16 100644
--- a/drivers/mtd/ubi/misc.c
+++ b/drivers/mtd/ubi/misc.c
@@ -74,6 +74,8 @@ int ubi_check_volume(struct ubi_device *ubi, int vol_id)
 	for (i = 0; i < vol->used_ebs; i++) {
 		int size;
 
+		cond_resched();
+
 		if (i == vol->used_ebs - 1)
 			size = vol->last_eb_bytes;
 		else
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index f80ffaba9058..c5be82d9d345 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -50,13 +50,13 @@
 #define UBI_NAME_STR "ubi"
 
 /* Normal UBI messages */
-#define ubi_msg(ubi, fmt, ...) pr_notice("UBI-%d: %s:" fmt "\n", \
-					 ubi->ubi_num, __func__, ##__VA_ARGS__)
+#define ubi_msg(ubi, fmt, ...) pr_notice(UBI_NAME_STR "%d: " fmt "\n", \
+					 ubi->ubi_num, ##__VA_ARGS__)
 /* UBI warning messages */
-#define ubi_warn(ubi, fmt, ...) pr_warn("UBI-%d warning: %s: " fmt "\n", \
+#define ubi_warn(ubi, fmt, ...) pr_warn(UBI_NAME_STR "%d warning: %s: " fmt "\n", \
 					ubi->ubi_num, __func__, ##__VA_ARGS__)
 /* UBI error messages */
-#define ubi_err(ubi, fmt, ...) pr_err("UBI-%d error: %s: " fmt "\n", \
+#define ubi_err(ubi, fmt, ...) pr_err(UBI_NAME_STR "%d error: %s: " fmt "\n", \
 				      ubi->ubi_num, __func__, ##__VA_ARGS__)
 
 /* Background thread name pattern */
@@ -261,6 +261,7 @@ struct ubi_fm_pool {
  * @readers: number of users holding this volume in read-only mode
  * @writers: number of users holding this volume in read-write mode
  * @exclusive: whether somebody holds this volume in exclusive mode
+ * @metaonly: whether somebody is altering only meta data of this volume
  *
  * @reserved_pebs: how many physical eraseblocks are reserved for this volume
  * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
@@ -309,6 +310,7 @@ struct ubi_volume {
 	int readers;
 	int writers;
 	int exclusive;
+	int metaonly;
 
 	int reserved_pebs;
 	int vol_type;
@@ -339,7 +341,8 @@ struct ubi_volume {
 /**
  * struct ubi_volume_desc - UBI volume descriptor returned when it is opened.
  * @vol: reference to the corresponding volume description object
- * @mode: open mode (%UBI_READONLY, %UBI_READWRITE, or %UBI_EXCLUSIVE)
+ * @mode: open mode (%UBI_READONLY, %UBI_READWRITE, %UBI_EXCLUSIVE
+ * or %UBI_METAONLY)
  */
 struct ubi_volume_desc {
 	struct ubi_volume *vol;
@@ -390,7 +393,8 @@ struct ubi_debug_info {
  * @volumes_lock: protects @volumes, @rsvd_pebs, @avail_pebs, beb_rsvd_pebs,
  *                @beb_rsvd_level, @bad_peb_count, @good_peb_count, @vol_count,
  *                @vol->readers, @vol->writers, @vol->exclusive,
- *                @vol->ref_count, @vol->mapping and @vol->eba_tbl.
+ *                @vol->metaonly, @vol->ref_count, @vol->mapping and
+ *                @vol->eba_tbl.
  * @ref_count: count of references on the UBI device
  * @image_seq: image sequence number recorded on EC headers
  *
@@ -791,6 +795,9 @@ int ubi_eba_unmap_leb(struct ubi_device *ubi, struct ubi_volume *vol,
 		      int lnum);
 int ubi_eba_read_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
 		     void *buf, int offset, int len, int check);
+int ubi_eba_read_leb_sg(struct ubi_device *ubi, struct ubi_volume *vol,
+			struct ubi_sgl *sgl, int lnum, int offset, int len,
+			int check);
 int ubi_eba_write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
 		      const void *buf, int offset, int len);
 int ubi_eba_write_leb_st(struct ubi_device *ubi, struct ubi_volume *vol,
diff --git a/drivers/mtd/ubi/vtbl.c b/drivers/mtd/ubi/vtbl.c
index f8fc3081bbb4..68c9c5ea676f 100644
--- a/drivers/mtd/ubi/vtbl.c
+++ b/drivers/mtd/ubi/vtbl.c
@@ -655,14 +655,13 @@ static int init_volumes(struct ubi_device *ubi,
 
 /**
  * check_av - check volume attaching information.
- * @ubi: UBI device description object
  * @vol: UBI volume description object
  * @av: volume attaching information
  *
  * This function returns zero if the volume attaching information is consistent
  * to the data read from the volume tabla, and %-EINVAL if not.
  */
-static int check_av(const struct ubi_device *ubi, const struct ubi_volume *vol,
+static int check_av(const struct ubi_volume *vol,
 		    const struct ubi_ainf_volume *av)
 {
 	int err;
@@ -690,7 +689,7 @@ static int check_av(const struct ubi_device *ubi, const struct ubi_volume *vol,
 	return 0;
 
 bad:
-	ubi_err(ubi, "bad attaching information, error %d", err);
+	ubi_err(vol->ubi, "bad attaching information, error %d", err);
 	ubi_dump_av(av);
 	ubi_dump_vol_info(vol);
 	return -EINVAL;
@@ -753,7 +752,7 @@ static int check_attaching_info(const struct ubi_device *ubi,
 			ubi_msg(ubi, "finish volume %d removal", av->vol_id);
 			ubi_remove_av(ai, av);
 		} else if (av) {
-			err = check_av(ubi, vol, av);
+			err = check_av(vol, av);
 			if (err)
 				return err;
 		}
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
index 834f6fe1f5fa..8f7bde6a85d6 100644
--- a/drivers/mtd/ubi/wl.c
+++ b/drivers/mtd/ubi/wl.c
@@ -470,11 +470,8 @@ struct ubi_wl_entry *ubi_wl_get_fm_peb(struct ubi_device *ubi, int anchor)
 {
 	struct ubi_wl_entry *e = NULL;
 
-	if (!ubi->free.rb_node || (ubi->free_count - ubi->beb_rsvd_pebs < 1)) {
-		ubi_warn(ubi, "Can't get peb for fastmap:anchor=%d, free_cnt=%d, reserved=%d",
-			 anchor, ubi->free_count, ubi->beb_rsvd_pebs);
+	if (!ubi->free.rb_node || (ubi->free_count - ubi->beb_rsvd_pebs < 1))
 		goto out;
-	}
 
 	if (anchor)
 		e = find_anchor_wl_entry(&ubi->free);
@@ -1806,11 +1803,8 @@ int ubi_thread(void *u)
 	for (;;) {
 		int err;
 
-		if (kthread_should_stop()) {
-			ubi_msg(ubi, "background thread \"%s\" should stop, PID %d",
-				ubi->bgt_name, task_pid_nr(current));
+		if (kthread_should_stop())
 			break;
-		}
 
 		if (try_to_freeze())
 			continue;