[v4,08/11] block: kill merge_bvec_fn() completely

Commit Message

Ming Lin May 22, 2015, 6:18 p.m. UTC

From: Kent Overstreet <[e-mail]>

As generic_make_request() is now able to handle arbitrarily sized bios,
it's no longer necessary for each individual block driver to define its
own ->merge_bvec_fn() callback. Remove every invocation completely.

Cc: Jens Axboe <[e-mail]>
Cc: Lars Ellenberg <[e-mail]>
Cc: [e-mail]
Cc: Jiri Kosina <[e-mail]>
Cc: Yehuda Sadeh <[e-mail]>
Cc: Sage Weil <[e-mail]>
Cc: Alex Elder <[e-mail]>
Cc: [e-mail]
Cc: Alasdair Kergon <[e-mail]>
Cc: Mike Snitzer <[e-mail]>
Cc: [e-mail]
Cc: Neil Brown <[e-mail]>
Cc: [e-mail]
Cc: Christoph Hellwig <[e-mail]>
Cc: "Martin K. Petersen" <[e-mail]>
Signed-off-by: Kent Overstreet <[e-mail]>
[dpark: also remove ->merge_bvec_fn() in dm-thin as well as
 dm-era-target, and resolve merge conflicts]
Signed-off-by: Dongsu Park <[e-mail]>
Signed-off-by: Ming Lin <[e-mail]>
---
 block/blk-merge.c              |  17 +-----
 block/blk-settings.c           |  22 --------
 drivers/block/drbd/drbd_int.h  |   1 -
 drivers/block/drbd/drbd_main.c |   1 -
 drivers/block/drbd/drbd_req.c  |  35 ------------
 drivers/block/pktcdvd.c        |  21 -------
 drivers/block/rbd.c            |  47 ----------------
 drivers/md/dm-cache-target.c   |  21 -------
 drivers/md/dm-crypt.c          |  16 ------
 drivers/md/dm-era-target.c     |  15 -----
 drivers/md/dm-flakey.c         |  16 ------
 drivers/md/dm-linear.c         |  16 ------
 drivers/md/dm-log-writes.c     |  16 ------
 drivers/md/dm-snap.c           |  15 -----
 drivers/md/dm-stripe.c         |  21 -------
 drivers/md/dm-table.c          |   8 ---
 drivers/md/dm-thin.c           |  31 -----------
 drivers/md/dm-verity.c         |  16 ------
 drivers/md/dm.c                | 120 +---------------------------------------
 drivers/md/dm.h                |   2 -
 drivers/md/linear.c            |  43 ---------------
 drivers/md/md.c                |  26 ---------
 drivers/md/md.h                |  12 ----
 drivers/md/multipath.c         |  21 -------
 drivers/md/raid0.c             |  56 -------------------
 drivers/md/raid0.h             |   2 -
 drivers/md/raid1.c             |  58 +-------------------
 drivers/md/raid10.c            | 121 +----------------------------------------
 drivers/md/raid5.c             |  32 -----------
 include/linux/blkdev.h         |  10 ----
 include/linux/device-mapper.h  |   4 --
 31 files changed, 9 insertions(+), 833 deletions(-)

Comments

NeilBrown May 25, 2015, 5:49 a.m. UTC | #1

On Fri, 22 May 2015 11:18:40 -0700 Ming Lin <[e-mail]> wrote:

> From: Kent Overstreet <[e-mail]>
> 
> As generic_make_request() is now able to handle arbitrarily sized bios,
> it's no longer necessary for each individual block driver to define its
> own ->merge_bvec_fn() callback. Remove every invocation completely.
> 
> Cc: Jens Axboe <[e-mail]>
> Cc: Lars Ellenberg <[e-mail]>
> Cc: [e-mail]
> Cc: Jiri Kosina <[e-mail]>
> Cc: Yehuda Sadeh <[e-mail]>
> Cc: Sage Weil <[e-mail]>
> Cc: Alex Elder <[e-mail]>
> Cc: [e-mail]
> Cc: Alasdair Kergon <[e-mail]>
> Cc: Mike Snitzer <[e-mail]>
> Cc: [e-mail]
> Cc: Neil Brown <[e-mail]>
> Cc: [e-mail]
> Cc: Christoph Hellwig <[e-mail]>
> Cc: "Martin K. Petersen" <[e-mail]>
> Signed-off-by: Kent Overstreet <[e-mail]>
> [dpark: also remove ->merge_bvec_fn() in dm-thin as well as
>  dm-era-target, and resolve merge conflicts]
> Signed-off-by: Dongsu Park <[e-mail]>
> Signed-off-by: Ming Lin <[e-mail]>

Acked-by: NeilBrown <[e-mail]> (for the 'md' bits)

Very happy to see this happening!

Thanks,
NeilBrown


> ---
>  block/blk-merge.c              |  17 +-----
>  block/blk-settings.c           |  22 --------
>  drivers/block/drbd/drbd_int.h  |   1 -
>  drivers/block/drbd/drbd_main.c |   1 -
>  drivers/block/drbd/drbd_req.c  |  35 ------------
>  drivers/block/pktcdvd.c        |  21 -------
>  drivers/block/rbd.c            |  47 ----------------
>  drivers/md/dm-cache-target.c   |  21 -------
>  drivers/md/dm-crypt.c          |  16 ------
>  drivers/md/dm-era-target.c     |  15 -----
>  drivers/md/dm-flakey.c         |  16 ------
>  drivers/md/dm-linear.c         |  16 ------
>  drivers/md/dm-log-writes.c     |  16 ------
>  drivers/md/dm-snap.c           |  15 -----
>  drivers/md/dm-stripe.c         |  21 -------
>  drivers/md/dm-table.c          |   8 ---
>  drivers/md/dm-thin.c           |  31 -----------
>  drivers/md/dm-verity.c         |  16 ------
>  drivers/md/dm.c                | 120 +---------------------------------------
>  drivers/md/dm.h                |   2 -
>  drivers/md/linear.c            |  43 ---------------
>  drivers/md/md.c                |  26 ---------
>  drivers/md/md.h                |  12 ----
>  drivers/md/multipath.c         |  21 -------
>  drivers/md/raid0.c             |  56 -------------------
>  drivers/md/raid0.h             |   2 -
>  drivers/md/raid1.c             |  58 +-------------------
>  drivers/md/raid10.c            | 121 +----------------------------------------
>  drivers/md/raid5.c             |  32 -----------
>  include/linux/blkdev.h         |  10 ----
>  include/linux/device-mapper.h  |   4 --
>  31 files changed, 9 insertions(+), 833 deletions(-)
> 
> diff --git a/block/blk-merge.c b/block/blk-merge.c
> index dc14255..25cafb8 100644
> --- a/block/blk-merge.c
> +++ b/block/blk-merge.c
> @@ -69,24 +69,13 @@ static struct bio *blk_bio_segment_split(struct request_queue *q,
>  	struct bio *split;
>  	struct bio_vec bv, bvprv;
>  	struct bvec_iter iter;
> -	unsigned seg_size = 0, nsegs = 0;
> +	unsigned seg_size = 0, nsegs = 0, sectors = 0;
>  	int prev = 0;
>  
> -	struct bvec_merge_data bvm = {
> -		.bi_bdev	= bio->bi_bdev,
> -		.bi_sector	= bio->bi_iter.bi_sector,
> -		.bi_size	= 0,
> -		.bi_rw		= bio->bi_rw,
> -	};
> -
>  	bio_for_each_segment(bv, bio, iter) {
> -		if (q->merge_bvec_fn &&
> -		    q->merge_bvec_fn(q, &bvm, &bv) < (int) bv.bv_len)
> -			goto split;
> -
> -		bvm.bi_size += bv.bv_len;
> +		sectors += bv.bv_len >> 9;
>  
> -		if (bvm.bi_size >> 9 > queue_max_sectors(q))
> +		if (sectors > queue_max_sectors(q))
>  			goto split;
>  
>  		/*
> diff --git a/block/blk-settings.c b/block/blk-settings.c
> index 12600bf..e90d477 100644
> --- a/block/blk-settings.c
> +++ b/block/blk-settings.c
> @@ -53,28 +53,6 @@ void blk_queue_unprep_rq(struct request_queue *q, unprep_rq_fn *ufn)
>  }
>  EXPORT_SYMBOL(blk_queue_unprep_rq);
>  
> -/**
> - * blk_queue_merge_bvec - set a merge_bvec function for queue
> - * @q:		queue
> - * @mbfn:	merge_bvec_fn
> - *
> - * Usually queues have static limitations on the max sectors or segments that
> - * we can put in a request. Stacking drivers may have some settings that
> - * are dynamic, and thus we have to query the queue whether it is ok to
> - * add a new bio_vec to a bio at a given offset or not. If the block device
> - * has such limitations, it needs to register a merge_bvec_fn to control
> - * the size of bio's sent to it. Note that a block device *must* allow a
> - * single page to be added to an empty bio. The block device driver may want
> - * to use the bio_split() function to deal with these bio's. By default
> - * no merge_bvec_fn is defined for a queue, and only the fixed limits are
> - * honored.
> - */
> -void blk_queue_merge_bvec(struct request_queue *q, merge_bvec_fn *mbfn)
> -{
> -	q->merge_bvec_fn = mbfn;
> -}
> -EXPORT_SYMBOL(blk_queue_merge_bvec);
> -
>  void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn)
>  {
>  	q->softirq_done_fn = fn;
> diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
> index b905e98..63ce2b0 100644
> --- a/drivers/block/drbd/drbd_int.h
> +++ b/drivers/block/drbd/drbd_int.h
> @@ -1449,7 +1449,6 @@ extern void do_submit(struct work_struct *ws);
>  extern void __drbd_make_request(struct drbd_device *, struct bio *, unsigned long);
>  extern void drbd_make_request(struct request_queue *q, struct bio *bio);
>  extern int drbd_read_remote(struct drbd_device *device, struct drbd_request *req);
> -extern int drbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct bio_vec *bvec);
>  extern int is_valid_ar_handle(struct drbd_request *, sector_t);
>  
>  
> diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
> index 81fde9e..771e68c 100644
> --- a/drivers/block/drbd/drbd_main.c
> +++ b/drivers/block/drbd/drbd_main.c
> @@ -2774,7 +2774,6 @@ enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig
>  	   This triggers a max_bio_size message upon first attach or connect */
>  	blk_queue_max_hw_sectors(q, DRBD_MAX_BIO_SIZE_SAFE >> 8);
>  	blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
> -	blk_queue_merge_bvec(q, drbd_merge_bvec);
>  	q->queue_lock = &resource->req_lock;
>  
>  	device->md_io.page = alloc_page(GFP_KERNEL);
> diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
> index a6265bc..7523f00 100644
> --- a/drivers/block/drbd/drbd_req.c
> +++ b/drivers/block/drbd/drbd_req.c
> @@ -1510,41 +1510,6 @@ void drbd_make_request(struct request_queue *q, struct bio *bio)
>  	__drbd_make_request(device, bio, start_jif);
>  }
>  
> -/* This is called by bio_add_page().
> - *
> - * q->max_hw_sectors and other global limits are already enforced there.
> - *
> - * We need to call down to our lower level device,
> - * in case it has special restrictions.
> - *
> - * We also may need to enforce configured max-bio-bvecs limits.
> - *
> - * As long as the BIO is empty we have to allow at least one bvec,
> - * regardless of size and offset, so no need to ask lower levels.
> - */
> -int drbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct bio_vec *bvec)
> -{
> -	struct drbd_device *device = (struct drbd_device *) q->queuedata;
> -	unsigned int bio_size = bvm->bi_size;
> -	int limit = DRBD_MAX_BIO_SIZE;
> -	int backing_limit;
> -
> -	if (bio_size && get_ldev(device)) {
> -		unsigned int max_hw_sectors = queue_max_hw_sectors(q);
> -		struct request_queue * const b =
> -			device->ldev->backing_bdev->bd_disk->queue;
> -		if (b->merge_bvec_fn) {
> -			bvm->bi_bdev = device->ldev->backing_bdev;
> -			backing_limit = b->merge_bvec_fn(b, bvm, bvec);
> -			limit = min(limit, backing_limit);
> -		}
> -		put_ldev(device);
> -		if ((limit >> 9) > max_hw_sectors)
> -			limit = max_hw_sectors << 9;
> -	}
> -	return limit;
> -}
> -
>  void request_timer_fn(unsigned long data)
>  {
>  	struct drbd_device *device = (struct drbd_device *) data;
> diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
> index ea10bd9..85eac23 100644
> --- a/drivers/block/pktcdvd.c
> +++ b/drivers/block/pktcdvd.c
> @@ -2505,26 +2505,6 @@ end_io:
>  
>  
>  
> -static int pkt_merge_bvec(struct request_queue *q, struct bvec_merge_data *bmd,
> -			  struct bio_vec *bvec)
> -{
> -	struct pktcdvd_device *pd = q->queuedata;
> -	sector_t zone = get_zone(bmd->bi_sector, pd);
> -	int used = ((bmd->bi_sector - zone) << 9) + bmd->bi_size;
> -	int remaining = (pd->settings.size << 9) - used;
> -	int remaining2;
> -
> -	/*
> -	 * A bio <= PAGE_SIZE must be allowed. If it crosses a packet
> -	 * boundary, pkt_make_request() will split the bio.
> -	 */
> -	remaining2 = PAGE_SIZE - bmd->bi_size;
> -	remaining = max(remaining, remaining2);
> -
> -	BUG_ON(remaining < 0);
> -	return remaining;
> -}
> -
>  static void pkt_init_queue(struct pktcdvd_device *pd)
>  {
>  	struct request_queue *q = pd->disk->queue;
> @@ -2532,7 +2512,6 @@ static void pkt_init_queue(struct pktcdvd_device *pd)
>  	blk_queue_make_request(q, pkt_make_request);
>  	blk_queue_logical_block_size(q, CD_FRAMESIZE);
>  	blk_queue_max_hw_sectors(q, PACKET_MAX_SECTORS);
> -	blk_queue_merge_bvec(q, pkt_merge_bvec);
>  	q->queuedata = pd;
>  }
>  
> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index ec6c5c6..f50edb3 100644
> --- a/drivers/block/rbd.c
> +++ b/drivers/block/rbd.c
> @@ -3440,52 +3440,6 @@ static int rbd_queue_rq(struct blk_mq_hw_ctx *hctx,
>  	return BLK_MQ_RQ_QUEUE_OK;
>  }
>  
> -/*
> - * a queue callback. Makes sure that we don't create a bio that spans across
> - * multiple osd objects. One exception would be with a single page bios,
> - * which we handle later at bio_chain_clone_range()
> - */
> -static int rbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bmd,
> -			  struct bio_vec *bvec)
> -{
> -	struct rbd_device *rbd_dev = q->queuedata;
> -	sector_t sector_offset;
> -	sector_t sectors_per_obj;
> -	sector_t obj_sector_offset;
> -	int ret;
> -
> -	/*
> -	 * Find how far into its rbd object the partition-relative
> -	 * bio start sector is to offset relative to the enclosing
> -	 * device.
> -	 */
> -	sector_offset = get_start_sect(bmd->bi_bdev) + bmd->bi_sector;
> -	sectors_per_obj = 1 << (rbd_dev->header.obj_order - SECTOR_SHIFT);
> -	obj_sector_offset = sector_offset & (sectors_per_obj - 1);
> -
> -	/*
> -	 * Compute the number of bytes from that offset to the end
> -	 * of the object.  Account for what's already used by the bio.
> -	 */
> -	ret = (int) (sectors_per_obj - obj_sector_offset) << SECTOR_SHIFT;
> -	if (ret > bmd->bi_size)
> -		ret -= bmd->bi_size;
> -	else
> -		ret = 0;
> -
> -	/*
> -	 * Don't send back more than was asked for.  And if the bio
> -	 * was empty, let the whole thing through because:  "Note
> -	 * that a block device *must* allow a single page to be
> -	 * added to an empty bio."
> -	 */
> -	rbd_assert(bvec->bv_len <= PAGE_SIZE);
> -	if (ret > (int) bvec->bv_len || !bmd->bi_size)
> -		ret = (int) bvec->bv_len;
> -
> -	return ret;
> -}
> -
>  static void rbd_free_disk(struct rbd_device *rbd_dev)
>  {
>  	struct gendisk *disk = rbd_dev->disk;
> @@ -3784,7 +3738,6 @@ static int rbd_init_disk(struct rbd_device *rbd_dev)
>  	q->limits.max_discard_sectors = segment_size / SECTOR_SIZE;
>  	q->limits.discard_zeroes_data = 1;
>  
> -	blk_queue_merge_bvec(q, rbd_merge_bvec);
>  	disk->queue = q;
>  
>  	q->queuedata = rbd_dev;
> diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
> index 7755af3..2e47e35 100644
> --- a/drivers/md/dm-cache-target.c
> +++ b/drivers/md/dm-cache-target.c
> @@ -3289,26 +3289,6 @@ static int cache_iterate_devices(struct dm_target *ti,
>  	return r;
>  }
>  
> -/*
> - * We assume I/O is going to the origin (which is the volume
> - * more likely to have restrictions e.g. by being striped).
> - * (Looking up the exact location of the data would be expensive
> - * and could always be out of date by the time the bio is submitted.)
> - */
> -static int cache_bvec_merge(struct dm_target *ti,
> -			    struct bvec_merge_data *bvm,
> -			    struct bio_vec *biovec, int max_size)
> -{
> -	struct cache *cache = ti->private;
> -	struct request_queue *q = bdev_get_queue(cache->origin_dev->bdev);
> -
> -	if (!q->merge_bvec_fn)
> -		return max_size;
> -
> -	bvm->bi_bdev = cache->origin_dev->bdev;
> -	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
> -}
> -
>  static void set_discard_limits(struct cache *cache, struct queue_limits *limits)
>  {
>  	/*
> @@ -3352,7 +3332,6 @@ static struct target_type cache_target = {
>  	.status = cache_status,
>  	.message = cache_message,
>  	.iterate_devices = cache_iterate_devices,
> -	.merge = cache_bvec_merge,
>  	.io_hints = cache_io_hints,
>  };
>  
> diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
> index 5503e43..d13f330 100644
> --- a/drivers/md/dm-crypt.c
> +++ b/drivers/md/dm-crypt.c
> @@ -2017,21 +2017,6 @@ error:
>  	return -EINVAL;
>  }
>  
> -static int crypt_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
> -		       struct bio_vec *biovec, int max_size)
> -{
> -	struct crypt_config *cc = ti->private;
> -	struct request_queue *q = bdev_get_queue(cc->dev->bdev);
> -
> -	if (!q->merge_bvec_fn)
> -		return max_size;
> -
> -	bvm->bi_bdev = cc->dev->bdev;
> -	bvm->bi_sector = cc->start + dm_target_offset(ti, bvm->bi_sector);
> -
> -	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
> -}
> -
>  static int crypt_iterate_devices(struct dm_target *ti,
>  				 iterate_devices_callout_fn fn, void *data)
>  {
> @@ -2052,7 +2037,6 @@ static struct target_type crypt_target = {
>  	.preresume = crypt_preresume,
>  	.resume = crypt_resume,
>  	.message = crypt_message,
> -	.merge  = crypt_merge,
>  	.iterate_devices = crypt_iterate_devices,
>  };
>  
> diff --git a/drivers/md/dm-era-target.c b/drivers/md/dm-era-target.c
> index ad913cd..0119ebf 100644
> --- a/drivers/md/dm-era-target.c
> +++ b/drivers/md/dm-era-target.c
> @@ -1673,20 +1673,6 @@ static int era_iterate_devices(struct dm_target *ti,
>  	return fn(ti, era->origin_dev, 0, get_dev_size(era->origin_dev), data);
>  }
>  
> -static int era_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
> -		     struct bio_vec *biovec, int max_size)
> -{
> -	struct era *era = ti->private;
> -	struct request_queue *q = bdev_get_queue(era->origin_dev->bdev);
> -
> -	if (!q->merge_bvec_fn)
> -		return max_size;
> -
> -	bvm->bi_bdev = era->origin_dev->bdev;
> -
> -	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
> -}
> -
>  static void era_io_hints(struct dm_target *ti, struct queue_limits *limits)
>  {
>  	struct era *era = ti->private;
> @@ -1717,7 +1703,6 @@ static struct target_type era_target = {
>  	.status = era_status,
>  	.message = era_message,
>  	.iterate_devices = era_iterate_devices,
> -	.merge = era_merge,
>  	.io_hints = era_io_hints
>  };
>  
> diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c
> index b257e46..d955b3e 100644
> --- a/drivers/md/dm-flakey.c
> +++ b/drivers/md/dm-flakey.c
> @@ -387,21 +387,6 @@ static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long ar
>  	return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
>  }
>  
> -static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
> -			struct bio_vec *biovec, int max_size)
> -{
> -	struct flakey_c *fc = ti->private;
> -	struct request_queue *q = bdev_get_queue(fc->dev->bdev);
> -
> -	if (!q->merge_bvec_fn)
> -		return max_size;
> -
> -	bvm->bi_bdev = fc->dev->bdev;
> -	bvm->bi_sector = flakey_map_sector(ti, bvm->bi_sector);
> -
> -	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
> -}
> -
>  static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
>  {
>  	struct flakey_c *fc = ti->private;
> @@ -419,7 +404,6 @@ static struct target_type flakey_target = {
>  	.end_io = flakey_end_io,
>  	.status = flakey_status,
>  	.ioctl	= flakey_ioctl,
> -	.merge	= flakey_merge,
>  	.iterate_devices = flakey_iterate_devices,
>  };
>  
> diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
> index 53e848c..7dd5fc8 100644
> --- a/drivers/md/dm-linear.c
> +++ b/drivers/md/dm-linear.c
> @@ -130,21 +130,6 @@ static int linear_ioctl(struct dm_target *ti, unsigned int cmd,
>  	return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
>  }
>  
> -static int linear_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
> -			struct bio_vec *biovec, int max_size)
> -{
> -	struct linear_c *lc = ti->private;
> -	struct request_queue *q = bdev_get_queue(lc->dev->bdev);
> -
> -	if (!q->merge_bvec_fn)
> -		return max_size;
> -
> -	bvm->bi_bdev = lc->dev->bdev;
> -	bvm->bi_sector = linear_map_sector(ti, bvm->bi_sector);
> -
> -	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
> -}
> -
>  static int linear_iterate_devices(struct dm_target *ti,
>  				  iterate_devices_callout_fn fn, void *data)
>  {
> @@ -162,7 +147,6 @@ static struct target_type linear_target = {
>  	.map    = linear_map,
>  	.status = linear_status,
>  	.ioctl  = linear_ioctl,
> -	.merge  = linear_merge,
>  	.iterate_devices = linear_iterate_devices,
>  };
>  
> diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
> index 93e0844..4325808 100644
> --- a/drivers/md/dm-log-writes.c
> +++ b/drivers/md/dm-log-writes.c
> @@ -728,21 +728,6 @@ static int log_writes_ioctl(struct dm_target *ti, unsigned int cmd,
>  	return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
>  }
>  
> -static int log_writes_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
> -			    struct bio_vec *biovec, int max_size)
> -{
> -	struct log_writes_c *lc = ti->private;
> -	struct request_queue *q = bdev_get_queue(lc->dev->bdev);
> -
> -	if (!q->merge_bvec_fn)
> -		return max_size;
> -
> -	bvm->bi_bdev = lc->dev->bdev;
> -	bvm->bi_sector = dm_target_offset(ti, bvm->bi_sector);
> -
> -	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
> -}
> -
>  static int log_writes_iterate_devices(struct dm_target *ti,
>  				      iterate_devices_callout_fn fn,
>  				      void *data)
> @@ -796,7 +781,6 @@ static struct target_type log_writes_target = {
>  	.end_io = normal_end_io,
>  	.status = log_writes_status,
>  	.ioctl	= log_writes_ioctl,
> -	.merge	= log_writes_merge,
>  	.message = log_writes_message,
>  	.iterate_devices = log_writes_iterate_devices,
>  	.io_hints = log_writes_io_hints,
> diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
> index f83a0f3..274cbec 100644
> --- a/drivers/md/dm-snap.c
> +++ b/drivers/md/dm-snap.c
> @@ -2331,20 +2331,6 @@ static void origin_status(struct dm_target *ti, status_type_t type,
>  	}
>  }
>  
> -static int origin_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
> -			struct bio_vec *biovec, int max_size)
> -{
> -	struct dm_origin *o = ti->private;
> -	struct request_queue *q = bdev_get_queue(o->dev->bdev);
> -
> -	if (!q->merge_bvec_fn)
> -		return max_size;
> -
> -	bvm->bi_bdev = o->dev->bdev;
> -
> -	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
> -}
> -
>  static int origin_iterate_devices(struct dm_target *ti,
>  				  iterate_devices_callout_fn fn, void *data)
>  {
> @@ -2363,7 +2349,6 @@ static struct target_type origin_target = {
>  	.resume  = origin_resume,
>  	.postsuspend = origin_postsuspend,
>  	.status  = origin_status,
> -	.merge	 = origin_merge,
>  	.iterate_devices = origin_iterate_devices,
>  };
>  
> diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
> index f8b37d4..09bb2fe 100644
> --- a/drivers/md/dm-stripe.c
> +++ b/drivers/md/dm-stripe.c
> @@ -412,26 +412,6 @@ static void stripe_io_hints(struct dm_target *ti,
>  	blk_limits_io_opt(limits, chunk_size * sc->stripes);
>  }
>  
> -static int stripe_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
> -			struct bio_vec *biovec, int max_size)
> -{
> -	struct stripe_c *sc = ti->private;
> -	sector_t bvm_sector = bvm->bi_sector;
> -	uint32_t stripe;
> -	struct request_queue *q;
> -
> -	stripe_map_sector(sc, bvm_sector, &stripe, &bvm_sector);
> -
> -	q = bdev_get_queue(sc->stripe[stripe].dev->bdev);
> -	if (!q->merge_bvec_fn)
> -		return max_size;
> -
> -	bvm->bi_bdev = sc->stripe[stripe].dev->bdev;
> -	bvm->bi_sector = sc->stripe[stripe].physical_start + bvm_sector;
> -
> -	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
> -}
> -
>  static struct target_type stripe_target = {
>  	.name   = "striped",
>  	.version = {1, 5, 1},
> @@ -443,7 +423,6 @@ static struct target_type stripe_target = {
>  	.status = stripe_status,
>  	.iterate_devices = stripe_iterate_devices,
>  	.io_hints = stripe_io_hints,
> -	.merge  = stripe_merge,
>  };
>  
>  int __init dm_stripe_init(void)
> diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> index d9b00b8..19c9b01 100644
> --- a/drivers/md/dm-table.c
> +++ b/drivers/md/dm-table.c
> @@ -440,14 +440,6 @@ static int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
>  		       q->limits.alignment_offset,
>  		       (unsigned long long) start << SECTOR_SHIFT);
>  
> -	/*
> -	 * Check if merge fn is supported.
> -	 * If not we'll force DM to use PAGE_SIZE or
> -	 * smaller I/O, just to be safe.
> -	 */
> -	if (dm_queue_merge_is_compulsory(q) && !ti->type->merge)
> -		blk_limits_max_hw_sectors(limits,
> -					  (unsigned int) (PAGE_SIZE >> 9));
>  	return 0;
>  }
>  
> diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
> index 921aafd..03552fe 100644
> --- a/drivers/md/dm-thin.c
> +++ b/drivers/md/dm-thin.c
> @@ -3562,20 +3562,6 @@ static int pool_iterate_devices(struct dm_target *ti,
>  	return fn(ti, pt->data_dev, 0, ti->len, data);
>  }
>  
> -static int pool_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
> -		      struct bio_vec *biovec, int max_size)
> -{
> -	struct pool_c *pt = ti->private;
> -	struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);
> -
> -	if (!q->merge_bvec_fn)
> -		return max_size;
> -
> -	bvm->bi_bdev = pt->data_dev->bdev;
> -
> -	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
> -}
> -
>  static void set_discard_limits(struct pool_c *pt, struct queue_limits *limits)
>  {
>  	struct pool *pool = pt->pool;
> @@ -3667,7 +3653,6 @@ static struct target_type pool_target = {
>  	.resume = pool_resume,
>  	.message = pool_message,
>  	.status = pool_status,
> -	.merge = pool_merge,
>  	.iterate_devices = pool_iterate_devices,
>  	.io_hints = pool_io_hints,
>  };
> @@ -3992,21 +3977,6 @@ err:
>  	DMEMIT("Error");
>  }
>  
> -static int thin_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
> -		      struct bio_vec *biovec, int max_size)
> -{
> -	struct thin_c *tc = ti->private;
> -	struct request_queue *q = bdev_get_queue(tc->pool_dev->bdev);
> -
> -	if (!q->merge_bvec_fn)
> -		return max_size;
> -
> -	bvm->bi_bdev = tc->pool_dev->bdev;
> -	bvm->bi_sector = dm_target_offset(ti, bvm->bi_sector);
> -
> -	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
> -}
> -
>  static int thin_iterate_devices(struct dm_target *ti,
>  				iterate_devices_callout_fn fn, void *data)
>  {
> @@ -4041,7 +4011,6 @@ static struct target_type thin_target = {
>  	.presuspend = thin_presuspend,
>  	.postsuspend = thin_postsuspend,
>  	.status = thin_status,
> -	.merge = thin_merge,
>  	.iterate_devices = thin_iterate_devices,
>  };
>  
> diff --git a/drivers/md/dm-verity.c b/drivers/md/dm-verity.c
> index 66616db..3b85460 100644
> --- a/drivers/md/dm-verity.c
> +++ b/drivers/md/dm-verity.c
> @@ -648,21 +648,6 @@ static int verity_ioctl(struct dm_target *ti, unsigned cmd,
>  				     cmd, arg);
>  }
>  
> -static int verity_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
> -			struct bio_vec *biovec, int max_size)
> -{
> -	struct dm_verity *v = ti->private;
> -	struct request_queue *q = bdev_get_queue(v->data_dev->bdev);
> -
> -	if (!q->merge_bvec_fn)
> -		return max_size;
> -
> -	bvm->bi_bdev = v->data_dev->bdev;
> -	bvm->bi_sector = verity_map_sector(v, bvm->bi_sector);
> -
> -	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
> -}
> -
>  static int verity_iterate_devices(struct dm_target *ti,
>  				  iterate_devices_callout_fn fn, void *data)
>  {
> @@ -995,7 +980,6 @@ static struct target_type verity_target = {
>  	.map		= verity_map,
>  	.status		= verity_status,
>  	.ioctl		= verity_ioctl,
> -	.merge		= verity_merge,
>  	.iterate_devices = verity_iterate_devices,
>  	.io_hints	= verity_io_hints,
>  };
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index 34f6063..f732a7a 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -121,9 +121,8 @@ EXPORT_SYMBOL_GPL(dm_get_rq_mapinfo);
>  #define DMF_FREEING 3
>  #define DMF_DELETING 4
>  #define DMF_NOFLUSH_SUSPENDING 5
> -#define DMF_MERGE_IS_OPTIONAL 6
> -#define DMF_DEFERRED_REMOVE 7
> -#define DMF_SUSPENDED_INTERNALLY 8
> +#define DMF_DEFERRED_REMOVE 6
> +#define DMF_SUSPENDED_INTERNALLY 7
>  
>  /*
>   * A dummy definition to make RCU happy.
> @@ -1717,60 +1716,6 @@ static void __split_and_process_bio(struct mapped_device *md,
>   * CRUD END
>   *---------------------------------------------------------------*/
>  
> -static int dm_merge_bvec(struct request_queue *q,
> -			 struct bvec_merge_data *bvm,
> -			 struct bio_vec *biovec)
> -{
> -	struct mapped_device *md = q->queuedata;
> -	struct dm_table *map = dm_get_live_table_fast(md);
> -	struct dm_target *ti;
> -	sector_t max_sectors;
> -	int max_size = 0;
> -
> -	if (unlikely(!map))
> -		goto out;
> -
> -	ti = dm_table_find_target(map, bvm->bi_sector);
> -	if (!dm_target_is_valid(ti))
> -		goto out;
> -
> -	/*
> -	 * Find maximum amount of I/O that won't need splitting
> -	 */
> -	max_sectors = min(max_io_len(bvm->bi_sector, ti),
> -			  (sector_t) queue_max_sectors(q));
> -	max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size;
> -	if (unlikely(max_size < 0)) /* this shouldn't _ever_ happen */
> -		max_size = 0;
> -
> -	/*
> -	 * merge_bvec_fn() returns number of bytes
> -	 * it can accept at this offset
> -	 * max is precomputed maximal io size
> -	 */
> -	if (max_size && ti->type->merge)
> -		max_size = ti->type->merge(ti, bvm, biovec, max_size);
> -	/*
> -	 * If the target doesn't support merge method and some of the devices
> -	 * provided their merge_bvec method (we know this by looking for the
> -	 * max_hw_sectors that dm_set_device_limits may set), then we can't
> -	 * allow bios with multiple vector entries.  So always set max_size
> -	 * to 0, and the code below allows just one page.
> -	 */
> -	else if (queue_max_hw_sectors(q) <= PAGE_SIZE >> 9)
> -		max_size = 0;
> -
> -out:
> -	dm_put_live_table_fast(md);
> -	/*
> -	 * Always allow an entire first page
> -	 */
> -	if (max_size <= biovec->bv_len && !(bvm->bi_size >> SECTOR_SHIFT))
> -		max_size = biovec->bv_len;
> -
> -	return max_size;
> -}
> -
>  /*
>   * The request function that just remaps the bio built up by
>   * dm_merge_bvec.
> @@ -2477,59 +2422,6 @@ static void __set_size(struct mapped_device *md, sector_t size)
>  }
>  
>  /*
> - * Return 1 if the queue has a compulsory merge_bvec_fn function.
> - *
> - * If this function returns 0, then the device is either a non-dm
> - * device without a merge_bvec_fn, or it is a dm device that is
> - * able to split any bios it receives that are too big.
> - */
> -int dm_queue_merge_is_compulsory(struct request_queue *q)
> -{
> -	struct mapped_device *dev_md;
> -
> -	if (!q->merge_bvec_fn)
> -		return 0;
> -
> -	if (q->make_request_fn == dm_make_request) {
> -		dev_md = q->queuedata;
> -		if (test_bit(DMF_MERGE_IS_OPTIONAL, &dev_md->flags))
> -			return 0;
> -	}
> -
> -	return 1;
> -}
> -
> -static int dm_device_merge_is_compulsory(struct dm_target *ti,
> -					 struct dm_dev *dev, sector_t start,
> -					 sector_t len, void *data)
> -{
> -	struct block_device *bdev = dev->bdev;
> -	struct request_queue *q = bdev_get_queue(bdev);
> -
> -	return dm_queue_merge_is_compulsory(q);
> -}
> -
> -/*
> - * Return 1 if it is acceptable to ignore merge_bvec_fn based
> - * on the properties of the underlying devices.
> - */
> -static int dm_table_merge_is_optional(struct dm_table *table)
> -{
> -	unsigned i = 0;
> -	struct dm_target *ti;
> -
> -	while (i < dm_table_get_num_targets(table)) {
> -		ti = dm_table_get_target(table, i++);
> -
> -		if (ti->type->iterate_devices &&
> -		    ti->type->iterate_devices(ti, dm_device_merge_is_compulsory, NULL))
> -			return 0;
> -	}
> -
> -	return 1;
> -}
> -
> -/*
>   * Returns old map, which caller must destroy.
>   */
>  static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
> @@ -2538,7 +2430,6 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
>  	struct dm_table *old_map;
>  	struct request_queue *q = md->queue;
>  	sector_t size;
> -	int merge_is_optional;
>  
>  	size = dm_table_get_size(t);
>  
> @@ -2564,17 +2455,11 @@ static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
>  
>  	__bind_mempools(md, t);
>  
> -	merge_is_optional = dm_table_merge_is_optional(t);
> -
>  	old_map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock));
>  	rcu_assign_pointer(md->map, t);
>  	md->immutable_target_type = dm_table_get_immutable_target_type(t);
>  
>  	dm_table_set_restrictions(t, q, limits);
> -	if (merge_is_optional)
> -		set_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
> -	else
> -		clear_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
>  	if (old_map)
>  		dm_sync_table(md);
>  
> @@ -2852,7 +2737,6 @@ int dm_setup_md_queue(struct mapped_device *md)
>  	case DM_TYPE_BIO_BASED:
>  		dm_init_old_md_queue(md);
>  		blk_queue_make_request(md->queue, dm_make_request);
> -		blk_queue_merge_bvec(md->queue, dm_merge_bvec);
>  		break;
>  	}
>  
> diff --git a/drivers/md/dm.h b/drivers/md/dm.h
> index 6123c2b..7d61cca 100644
> --- a/drivers/md/dm.h
> +++ b/drivers/md/dm.h
> @@ -77,8 +77,6 @@ bool dm_table_mq_request_based(struct dm_table *t);
>  void dm_table_free_md_mempools(struct dm_table *t);
>  struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t);
>  
> -int dm_queue_merge_is_compulsory(struct request_queue *q);
> -
>  void dm_lock_md_type(struct mapped_device *md);
>  void dm_unlock_md_type(struct mapped_device *md);
>  void dm_set_md_type(struct mapped_device *md, unsigned type);
> diff --git a/drivers/md/linear.c b/drivers/md/linear.c
> index fa7d577..8721ef9 100644
> --- a/drivers/md/linear.c
> +++ b/drivers/md/linear.c
> @@ -52,48 +52,6 @@ static inline struct dev_info *which_dev(struct mddev *mddev, sector_t sector)
>  	return conf->disks + lo;
>  }
>  
> -/**
> - *	linear_mergeable_bvec -- tell bio layer if two requests can be merged
> - *	@q: request queue
> - *	@bvm: properties of new bio
> - *	@biovec: the request that could be merged to it.
> - *
> - *	Return amount of bytes we can take at this offset
> - */
> -static int linear_mergeable_bvec(struct mddev *mddev,
> -				 struct bvec_merge_data *bvm,
> -				 struct bio_vec *biovec)
> -{
> -	struct dev_info *dev0;
> -	unsigned long maxsectors, bio_sectors = bvm->bi_size >> 9;
> -	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
> -	int maxbytes = biovec->bv_len;
> -	struct request_queue *subq;
> -
> -	dev0 = which_dev(mddev, sector);
> -	maxsectors = dev0->end_sector - sector;
> -	subq = bdev_get_queue(dev0->rdev->bdev);
> -	if (subq->merge_bvec_fn) {
> -		bvm->bi_bdev = dev0->rdev->bdev;
> -		bvm->bi_sector -= dev0->end_sector - dev0->rdev->sectors;
> -		maxbytes = min(maxbytes, subq->merge_bvec_fn(subq, bvm,
> -							     biovec));
> -	}
> -
> -	if (maxsectors < bio_sectors)
> -		maxsectors = 0;
> -	else
> -		maxsectors -= bio_sectors;
> -
> -	if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0)
> -		return maxbytes;
> -
> -	if (maxsectors > (maxbytes >> 9))
> -		return maxbytes;
> -	else
> -		return maxsectors << 9;
> -}
> -
>  static int linear_congested(struct mddev *mddev, int bits)
>  {
>  	struct linear_conf *conf;
> @@ -338,7 +296,6 @@ static struct md_personality linear_personality =
>  	.size		= linear_size,
>  	.quiesce	= linear_quiesce,
>  	.congested	= linear_congested,
> -	.mergeable_bvec	= linear_mergeable_bvec,
>  };
>  
>  static int __init linear_init (void)
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 046b3c9..f101981 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -352,29 +352,6 @@ static int md_congested(void *data, int bits)
>  	return mddev_congested(mddev, bits);
>  }
>  
> -static int md_mergeable_bvec(struct request_queue *q,
> -			     struct bvec_merge_data *bvm,
> -			     struct bio_vec *biovec)
> -{
> -	struct mddev *mddev = q->queuedata;
> -	int ret;
> -	rcu_read_lock();
> -	if (mddev->suspended) {
> -		/* Must always allow one vec */
> -		if (bvm->bi_size == 0)
> -			ret = biovec->bv_len;
> -		else
> -			ret = 0;
> -	} else {
> -		struct md_personality *pers = mddev->pers;
> -		if (pers && pers->mergeable_bvec)
> -			ret = pers->mergeable_bvec(mddev, bvm, biovec);
> -		else
> -			ret = biovec->bv_len;
> -	}
> -	rcu_read_unlock();
> -	return ret;
> -}
>  /*
>   * Generic flush handling for md
>   */
> @@ -5165,7 +5142,6 @@ int md_run(struct mddev *mddev)
>  	if (mddev->queue) {
>  		mddev->queue->backing_dev_info.congested_data = mddev;
>  		mddev->queue->backing_dev_info.congested_fn = md_congested;
> -		blk_queue_merge_bvec(mddev->queue, md_mergeable_bvec);
>  	}
>  	if (pers->sync_request) {
>  		if (mddev->kobj.sd &&
> @@ -5293,7 +5269,6 @@ static void md_clean(struct mddev *mddev)
>  	mddev->changed = 0;
>  	mddev->degraded = 0;
>  	mddev->safemode = 0;
> -	mddev->merge_check_needed = 0;
>  	mddev->bitmap_info.offset = 0;
>  	mddev->bitmap_info.default_offset = 0;
>  	mddev->bitmap_info.default_space = 0;
> @@ -5489,7 +5464,6 @@ static int do_md_stop(struct mddev *mddev, int mode,
>  
>  		__md_stop_writes(mddev);
>  		__md_stop(mddev);
> -		mddev->queue->merge_bvec_fn = NULL;
>  		mddev->queue->backing_dev_info.congested_fn = NULL;
>  
>  		/* tell userspace to handle 'inactive' */
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index 4046a6c..cf7141a 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -133,10 +133,6 @@ enum flag_bits {
>  	Bitmap_sync,		/* ..actually, not quite In_sync.  Need a
>  				 * bitmap-based recovery to get fully in sync
>  				 */
> -	Unmerged,		/* device is being added to array and should
> -				 * be considerred for bvec_merge_fn but not
> -				 * yet for actual IO
> -				 */
>  	WriteMostly,		/* Avoid reading if at all possible */
>  	AutoDetected,		/* added by auto-detect */
>  	Blocked,		/* An error occurred but has not yet
> @@ -373,10 +369,6 @@ struct mddev {
>  	int				degraded;	/* whether md should consider
>  							 * adding a spare
>  							 */
> -	int				merge_check_needed; /* at least one
> -							     * member device
> -							     * has a
> -							     * merge_bvec_fn */
>  
>  	atomic_t			recovery_active; /* blocks scheduled, but not written */
>  	wait_queue_head_t		recovery_wait;
> @@ -531,10 +523,6 @@ struct md_personality
>  	/* congested implements bdi.congested_fn().
>  	 * Will not be called while array is 'suspended' */
>  	int (*congested)(struct mddev *mddev, int bits);
> -	/* mergeable_bvec is use to implement ->merge_bvec_fn */
> -	int (*mergeable_bvec)(struct mddev *mddev,
> -			      struct bvec_merge_data *bvm,
> -			      struct bio_vec *biovec);
>  };
>  
>  struct md_sysfs_entry {
> diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c
> index ac3ede2..7ee27fb 100644
> --- a/drivers/md/multipath.c
> +++ b/drivers/md/multipath.c
> @@ -257,18 +257,6 @@ static int multipath_add_disk(struct mddev *mddev, struct md_rdev *rdev)
>  			disk_stack_limits(mddev->gendisk, rdev->bdev,
>  					  rdev->data_offset << 9);
>  
> -		/* as we don't honour merge_bvec_fn, we must never risk
> -		 * violating it, so limit ->max_segments to one, lying
> -		 * within a single page.
> -		 * (Note: it is very unlikely that a device with
> -		 * merge_bvec_fn will be involved in multipath.)
> -		 */
> -			if (q->merge_bvec_fn) {
> -				blk_queue_max_segments(mddev->queue, 1);
> -				blk_queue_segment_boundary(mddev->queue,
> -							   PAGE_CACHE_SIZE - 1);
> -			}
> -
>  			spin_lock_irq(&conf->device_lock);
>  			mddev->degraded--;
>  			rdev->raid_disk = path;
> @@ -432,15 +420,6 @@ static int multipath_run (struct mddev *mddev)
>  		disk_stack_limits(mddev->gendisk, rdev->bdev,
>  				  rdev->data_offset << 9);
>  
> -		/* as we don't honour merge_bvec_fn, we must never risk
> -		 * violating it, not that we ever expect a device with
> -		 * a merge_bvec_fn to be involved in multipath */
> -		if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
> -			blk_queue_max_segments(mddev->queue, 1);
> -			blk_queue_segment_boundary(mddev->queue,
> -						   PAGE_CACHE_SIZE - 1);
> -		}
> -
>  		if (!test_bit(Faulty, &rdev->flags))
>  			working_disks++;
>  	}
> diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
> index 6a68ef5..1440bd4 100644
> --- a/drivers/md/raid0.c
> +++ b/drivers/md/raid0.c
> @@ -192,9 +192,6 @@ static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
>  			disk_stack_limits(mddev->gendisk, rdev1->bdev,
>  					  rdev1->data_offset << 9);
>  
> -		if (rdev1->bdev->bd_disk->queue->merge_bvec_fn)
> -			conf->has_merge_bvec = 1;
> -
>  		if (!smallest || (rdev1->sectors < smallest->sectors))
>  			smallest = rdev1;
>  		cnt++;
> @@ -351,58 +348,6 @@ static struct md_rdev *map_sector(struct mddev *mddev, struct strip_zone *zone,
>  			     + sector_div(sector, zone->nb_dev)];
>  }
>  
> -/**
> - *	raid0_mergeable_bvec -- tell bio layer if two requests can be merged
> - *	@mddev: the md device
> - *	@bvm: properties of new bio
> - *	@biovec: the request that could be merged to it.
> - *
> - *	Return amount of bytes we can accept at this offset
> - */
> -static int raid0_mergeable_bvec(struct mddev *mddev,
> -				struct bvec_merge_data *bvm,
> -				struct bio_vec *biovec)
> -{
> -	struct r0conf *conf = mddev->private;
> -	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
> -	sector_t sector_offset = sector;
> -	int max;
> -	unsigned int chunk_sectors = mddev->chunk_sectors;
> -	unsigned int bio_sectors = bvm->bi_size >> 9;
> -	struct strip_zone *zone;
> -	struct md_rdev *rdev;
> -	struct request_queue *subq;
> -
> -	if (is_power_of_2(chunk_sectors))
> -		max =  (chunk_sectors - ((sector & (chunk_sectors-1))
> -						+ bio_sectors)) << 9;
> -	else
> -		max =  (chunk_sectors - (sector_div(sector, chunk_sectors)
> -						+ bio_sectors)) << 9;
> -	if (max < 0)
> -		max = 0; /* bio_add cannot handle a negative return */
> -	if (max <= biovec->bv_len && bio_sectors == 0)
> -		return biovec->bv_len;
> -	if (max < biovec->bv_len)
> -		/* too small already, no need to check further */
> -		return max;
> -	if (!conf->has_merge_bvec)
> -		return max;
> -
> -	/* May need to check subordinate device */
> -	sector = sector_offset;
> -	zone = find_zone(mddev->private, &sector_offset);
> -	rdev = map_sector(mddev, zone, sector, &sector_offset);
> -	subq = bdev_get_queue(rdev->bdev);
> -	if (subq->merge_bvec_fn) {
> -		bvm->bi_bdev = rdev->bdev;
> -		bvm->bi_sector = sector_offset + zone->dev_start +
> -			rdev->data_offset;
> -		return min(max, subq->merge_bvec_fn(subq, bvm, biovec));
> -	} else
> -		return max;
> -}
> -
>  static sector_t raid0_size(struct mddev *mddev, sector_t sectors, int raid_disks)
>  {
>  	sector_t array_sectors = 0;
> @@ -725,7 +670,6 @@ static struct md_personality raid0_personality=
>  	.takeover	= raid0_takeover,
>  	.quiesce	= raid0_quiesce,
>  	.congested	= raid0_congested,
> -	.mergeable_bvec	= raid0_mergeable_bvec,
>  };
>  
>  static int __init raid0_init (void)
> diff --git a/drivers/md/raid0.h b/drivers/md/raid0.h
> index 05539d9..7127a62 100644
> --- a/drivers/md/raid0.h
> +++ b/drivers/md/raid0.h
> @@ -12,8 +12,6 @@ struct r0conf {
>  	struct md_rdev		**devlist; /* lists of rdevs, pointed to
>  					    * by strip_zone->dev */
>  	int			nr_strip_zones;
> -	int			has_merge_bvec;	/* at least one member has
> -						 * a merge_bvec_fn */
>  };
>  
>  #endif
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index 9157a29..478878f 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -557,7 +557,6 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect
>  		rdev = rcu_dereference(conf->mirrors[disk].rdev);
>  		if (r1_bio->bios[disk] == IO_BLOCKED
>  		    || rdev == NULL
> -		    || test_bit(Unmerged, &rdev->flags)
>  		    || test_bit(Faulty, &rdev->flags))
>  			continue;
>  		if (!test_bit(In_sync, &rdev->flags) &&
> @@ -708,38 +707,6 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect
>  	return best_disk;
>  }
>  
> -static int raid1_mergeable_bvec(struct mddev *mddev,
> -				struct bvec_merge_data *bvm,
> -				struct bio_vec *biovec)
> -{
> -	struct r1conf *conf = mddev->private;
> -	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
> -	int max = biovec->bv_len;
> -
> -	if (mddev->merge_check_needed) {
> -		int disk;
> -		rcu_read_lock();
> -		for (disk = 0; disk < conf->raid_disks * 2; disk++) {
> -			struct md_rdev *rdev = rcu_dereference(
> -				conf->mirrors[disk].rdev);
> -			if (rdev && !test_bit(Faulty, &rdev->flags)) {
> -				struct request_queue *q =
> -					bdev_get_queue(rdev->bdev);
> -				if (q->merge_bvec_fn) {
> -					bvm->bi_sector = sector +
> -						rdev->data_offset;
> -					bvm->bi_bdev = rdev->bdev;
> -					max = min(max, q->merge_bvec_fn(
> -							  q, bvm, biovec));
> -				}
> -			}
> -		}
> -		rcu_read_unlock();
> -	}
> -	return max;
> -
> -}
> -
>  static int raid1_congested(struct mddev *mddev, int bits)
>  {
>  	struct r1conf *conf = mddev->private;
> @@ -1268,8 +1235,7 @@ read_again:
>  			break;
>  		}
>  		r1_bio->bios[i] = NULL;
> -		if (!rdev || test_bit(Faulty, &rdev->flags)
> -		    || test_bit(Unmerged, &rdev->flags)) {
> +		if (!rdev || test_bit(Faulty, &rdev->flags)) {
>  			if (i < conf->raid_disks)
>  				set_bit(R1BIO_Degraded, &r1_bio->state);
>  			continue;
> @@ -1614,7 +1580,6 @@ static int raid1_add_disk(struct mddev *mddev, struct md_rdev *rdev)
>  	struct raid1_info *p;
>  	int first = 0;
>  	int last = conf->raid_disks - 1;
> -	struct request_queue *q = bdev_get_queue(rdev->bdev);
>  
>  	if (mddev->recovery_disabled == conf->recovery_disabled)
>  		return -EBUSY;
> @@ -1622,11 +1587,6 @@ static int raid1_add_disk(struct mddev *mddev, struct md_rdev *rdev)
>  	if (rdev->raid_disk >= 0)
>  		first = last = rdev->raid_disk;
>  
> -	if (q->merge_bvec_fn) {
> -		set_bit(Unmerged, &rdev->flags);
> -		mddev->merge_check_needed = 1;
> -	}
> -
>  	for (mirror = first; mirror <= last; mirror++) {
>  		p = conf->mirrors+mirror;
>  		if (!p->rdev) {
> @@ -1658,19 +1618,6 @@ static int raid1_add_disk(struct mddev *mddev, struct md_rdev *rdev)
>  			break;
>  		}
>  	}
> -	if (err == 0 && test_bit(Unmerged, &rdev->flags)) {
> -		/* Some requests might not have seen this new
> -		 * merge_bvec_fn.  We must wait for them to complete
> -		 * before merging the device fully.
> -		 * First we make sure any code which has tested
> -		 * our function has submitted the request, then
> -		 * we wait for all outstanding requests to complete.
> -		 */
> -		synchronize_sched();
> -		freeze_array(conf, 0);
> -		unfreeze_array(conf);
> -		clear_bit(Unmerged, &rdev->flags);
> -	}
>  	md_integrity_add_rdev(rdev, mddev);
>  	if (mddev->queue && blk_queue_discard(bdev_get_queue(rdev->bdev)))
>  		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
> @@ -2807,8 +2754,6 @@ static struct r1conf *setup_conf(struct mddev *mddev)
>  			goto abort;
>  		disk->rdev = rdev;
>  		q = bdev_get_queue(rdev->bdev);
> -		if (q->merge_bvec_fn)
> -			mddev->merge_check_needed = 1;
>  
>  		disk->head_position = 0;
>  		disk->seq_start = MaxSector;
> @@ -3173,7 +3118,6 @@ static struct md_personality raid1_personality =
>  	.quiesce	= raid1_quiesce,
>  	.takeover	= raid1_takeover,
>  	.congested	= raid1_congested,
> -	.mergeable_bvec	= raid1_mergeable_bvec,
>  };
>  
>  static int __init raid_init(void)
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index e793ab6..a46c402 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -672,93 +672,6 @@ static sector_t raid10_find_virt(struct r10conf *conf, sector_t sector, int dev)
>  	return (vchunk << geo->chunk_shift) + offset;
>  }
>  
> -/**
> - *	raid10_mergeable_bvec -- tell bio layer if a two requests can be merged
> - *	@mddev: the md device
> - *	@bvm: properties of new bio
> - *	@biovec: the request that could be merged to it.
> - *
> - *	Return amount of bytes we can accept at this offset
> - *	This requires checking for end-of-chunk if near_copies != raid_disks,
> - *	and for subordinate merge_bvec_fns if merge_check_needed.
> - */
> -static int raid10_mergeable_bvec(struct mddev *mddev,
> -				 struct bvec_merge_data *bvm,
> -				 struct bio_vec *biovec)
> -{
> -	struct r10conf *conf = mddev->private;
> -	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
> -	int max;
> -	unsigned int chunk_sectors;
> -	unsigned int bio_sectors = bvm->bi_size >> 9;
> -	struct geom *geo = &conf->geo;
> -
> -	chunk_sectors = (conf->geo.chunk_mask & conf->prev.chunk_mask) + 1;
> -	if (conf->reshape_progress != MaxSector &&
> -	    ((sector >= conf->reshape_progress) !=
> -	     conf->mddev->reshape_backwards))
> -		geo = &conf->prev;
> -
> -	if (geo->near_copies < geo->raid_disks) {
> -		max = (chunk_sectors - ((sector & (chunk_sectors - 1))
> -					+ bio_sectors)) << 9;
> -		if (max < 0)
> -			/* bio_add cannot handle a negative return */
> -			max = 0;
> -		if (max <= biovec->bv_len && bio_sectors == 0)
> -			return biovec->bv_len;
> -	} else
> -		max = biovec->bv_len;
> -
> -	if (mddev->merge_check_needed) {
> -		struct {
> -			struct r10bio r10_bio;
> -			struct r10dev devs[conf->copies];
> -		} on_stack;
> -		struct r10bio *r10_bio = &on_stack.r10_bio;
> -		int s;
> -		if (conf->reshape_progress != MaxSector) {
> -			/* Cannot give any guidance during reshape */
> -			if (max <= biovec->bv_len && bio_sectors == 0)
> -				return biovec->bv_len;
> -			return 0;
> -		}
> -		r10_bio->sector = sector;
> -		raid10_find_phys(conf, r10_bio);
> -		rcu_read_lock();
> -		for (s = 0; s < conf->copies; s++) {
> -			int disk = r10_bio->devs[s].devnum;
> -			struct md_rdev *rdev = rcu_dereference(
> -				conf->mirrors[disk].rdev);
> -			if (rdev && !test_bit(Faulty, &rdev->flags)) {
> -				struct request_queue *q =
> -					bdev_get_queue(rdev->bdev);
> -				if (q->merge_bvec_fn) {
> -					bvm->bi_sector = r10_bio->devs[s].addr
> -						+ rdev->data_offset;
> -					bvm->bi_bdev = rdev->bdev;
> -					max = min(max, q->merge_bvec_fn(
> -							  q, bvm, biovec));
> -				}
> -			}
> -			rdev = rcu_dereference(conf->mirrors[disk].replacement);
> -			if (rdev && !test_bit(Faulty, &rdev->flags)) {
> -				struct request_queue *q =
> -					bdev_get_queue(rdev->bdev);
> -				if (q->merge_bvec_fn) {
> -					bvm->bi_sector = r10_bio->devs[s].addr
> -						+ rdev->data_offset;
> -					bvm->bi_bdev = rdev->bdev;
> -					max = min(max, q->merge_bvec_fn(
> -							  q, bvm, biovec));
> -				}
> -			}
> -		}
> -		rcu_read_unlock();
> -	}
> -	return max;
> -}
> -
>  /*
>   * This routine returns the disk from which the requested read should
>   * be done. There is a per-array 'next expected sequential IO' sector
> @@ -821,12 +734,10 @@ retry:
>  		disk = r10_bio->devs[slot].devnum;
>  		rdev = rcu_dereference(conf->mirrors[disk].replacement);
>  		if (rdev == NULL || test_bit(Faulty, &rdev->flags) ||
> -		    test_bit(Unmerged, &rdev->flags) ||
>  		    r10_bio->devs[slot].addr + sectors > rdev->recovery_offset)
>  			rdev = rcu_dereference(conf->mirrors[disk].rdev);
>  		if (rdev == NULL ||
> -		    test_bit(Faulty, &rdev->flags) ||
> -		    test_bit(Unmerged, &rdev->flags))
> +		    test_bit(Faulty, &rdev->flags))
>  			continue;
>  		if (!test_bit(In_sync, &rdev->flags) &&
>  		    r10_bio->devs[slot].addr + sectors > rdev->recovery_offset)
> @@ -1326,11 +1237,9 @@ retry_write:
>  			blocked_rdev = rrdev;
>  			break;
>  		}
> -		if (rdev && (test_bit(Faulty, &rdev->flags)
> -			     || test_bit(Unmerged, &rdev->flags)))
> +		if (rdev && (test_bit(Faulty, &rdev->flags)))
>  			rdev = NULL;
> -		if (rrdev && (test_bit(Faulty, &rrdev->flags)
> -			      || test_bit(Unmerged, &rrdev->flags)))
> +		if (rrdev && (test_bit(Faulty, &rrdev->flags)))
>  			rrdev = NULL;
>  
>  		r10_bio->devs[i].bio = NULL;
> @@ -1777,7 +1686,6 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
>  	int mirror;
>  	int first = 0;
>  	int last = conf->geo.raid_disks - 1;
> -	struct request_queue *q = bdev_get_queue(rdev->bdev);
>  
>  	if (mddev->recovery_cp < MaxSector)
>  		/* only hot-add to in-sync arrays, as recovery is
> @@ -1790,11 +1698,6 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
>  	if (rdev->raid_disk >= 0)
>  		first = last = rdev->raid_disk;
>  
> -	if (q->merge_bvec_fn) {
> -		set_bit(Unmerged, &rdev->flags);
> -		mddev->merge_check_needed = 1;
> -	}
> -
>  	if (rdev->saved_raid_disk >= first &&
>  	    conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
>  		mirror = rdev->saved_raid_disk;
> @@ -1833,19 +1736,6 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
>  		rcu_assign_pointer(p->rdev, rdev);
>  		break;
>  	}
> -	if (err == 0 && test_bit(Unmerged, &rdev->flags)) {
> -		/* Some requests might not have seen this new
> -		 * merge_bvec_fn.  We must wait for them to complete
> -		 * before merging the device fully.
> -		 * First we make sure any code which has tested
> -		 * our function has submitted the request, then
> -		 * we wait for all outstanding requests to complete.
> -		 */
> -		synchronize_sched();
> -		freeze_array(conf, 0);
> -		unfreeze_array(conf);
> -		clear_bit(Unmerged, &rdev->flags);
> -	}
>  	md_integrity_add_rdev(rdev, mddev);
>  	if (mddev->queue && blk_queue_discard(bdev_get_queue(rdev->bdev)))
>  		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
> @@ -2404,7 +2294,6 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
>  			d = r10_bio->devs[sl].devnum;
>  			rdev = rcu_dereference(conf->mirrors[d].rdev);
>  			if (rdev &&
> -			    !test_bit(Unmerged, &rdev->flags) &&
>  			    test_bit(In_sync, &rdev->flags) &&
>  			    is_badblock(rdev, r10_bio->devs[sl].addr + sect, s,
>  					&first_bad, &bad_sectors) == 0) {
> @@ -2458,7 +2347,6 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
>  			d = r10_bio->devs[sl].devnum;
>  			rdev = rcu_dereference(conf->mirrors[d].rdev);
>  			if (!rdev ||
> -			    test_bit(Unmerged, &rdev->flags) ||
>  			    !test_bit(In_sync, &rdev->flags))
>  				continue;
>  
> @@ -3652,8 +3540,6 @@ static int run(struct mddev *mddev)
>  			disk->rdev = rdev;
>  		}
>  		q = bdev_get_queue(rdev->bdev);
> -		if (q->merge_bvec_fn)
> -			mddev->merge_check_needed = 1;
>  		diff = (rdev->new_data_offset - rdev->data_offset);
>  		if (!mddev->reshape_backwards)
>  			diff = -diff;
> @@ -4706,7 +4592,6 @@ static struct md_personality raid10_personality =
>  	.start_reshape	= raid10_start_reshape,
>  	.finish_reshape	= raid10_finish_reshape,
>  	.congested	= raid10_congested,
> -	.mergeable_bvec	= raid10_mergeable_bvec,
>  };
>  
>  static int __init raid_init(void)
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index b6c6ace..18d2b23 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -4625,35 +4625,6 @@ static int raid5_congested(struct mddev *mddev, int bits)
>  	return 0;
>  }
>  
> -/* We want read requests to align with chunks where possible,
> - * but write requests don't need to.
> - */
> -static int raid5_mergeable_bvec(struct mddev *mddev,
> -				struct bvec_merge_data *bvm,
> -				struct bio_vec *biovec)
> -{
> -	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
> -	int max;
> -	unsigned int chunk_sectors = mddev->chunk_sectors;
> -	unsigned int bio_sectors = bvm->bi_size >> 9;
> -
> -	/*
> -	 * always allow writes to be mergeable, read as well if array
> -	 * is degraded as we'll go through stripe cache anyway.
> -	 */
> -	if ((bvm->bi_rw & 1) == WRITE || mddev->degraded)
> -		return biovec->bv_len;
> -
> -	if (mddev->new_chunk_sectors < mddev->chunk_sectors)
> -		chunk_sectors = mddev->new_chunk_sectors;
> -	max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
> -	if (max < 0) max = 0;
> -	if (max <= biovec->bv_len && bio_sectors == 0)
> -		return biovec->bv_len;
> -	else
> -		return max;
> -}
> -
>  static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
>  {
>  	sector_t sector = bio->bi_iter.bi_sector + get_start_sect(bio->bi_bdev);
> @@ -7722,7 +7693,6 @@ static struct md_personality raid6_personality =
>  	.quiesce	= raid5_quiesce,
>  	.takeover	= raid6_takeover,
>  	.congested	= raid5_congested,
> -	.mergeable_bvec	= raid5_mergeable_bvec,
>  };
>  static struct md_personality raid5_personality =
>  {
> @@ -7746,7 +7716,6 @@ static struct md_personality raid5_personality =
>  	.quiesce	= raid5_quiesce,
>  	.takeover	= raid5_takeover,
>  	.congested	= raid5_congested,
> -	.mergeable_bvec	= raid5_mergeable_bvec,
>  };
>  
>  static struct md_personality raid4_personality =
> @@ -7771,7 +7740,6 @@ static struct md_personality raid4_personality =
>  	.quiesce	= raid5_quiesce,
>  	.takeover	= raid4_takeover,
>  	.congested	= raid5_congested,
> -	.mergeable_bvec	= raid5_mergeable_bvec,
>  };
>  
>  static int __init raid5_init(void)
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 93b81a2..6927b76 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -239,14 +239,6 @@ typedef int (prep_rq_fn) (struct request_queue *, struct request *);
>  typedef void (unprep_rq_fn) (struct request_queue *, struct request *);
>  
>  struct bio_vec;
> -struct bvec_merge_data {
> -	struct block_device *bi_bdev;
> -	sector_t bi_sector;
> -	unsigned bi_size;
> -	unsigned long bi_rw;
> -};
> -typedef int (merge_bvec_fn) (struct request_queue *, struct bvec_merge_data *,
> -			     struct bio_vec *);
>  typedef void (softirq_done_fn)(struct request *);
>  typedef int (dma_drain_needed_fn)(struct request *);
>  typedef int (lld_busy_fn) (struct request_queue *q);
> @@ -331,7 +323,6 @@ struct request_queue {
>  	make_request_fn		*make_request_fn;
>  	prep_rq_fn		*prep_rq_fn;
>  	unprep_rq_fn		*unprep_rq_fn;
> -	merge_bvec_fn		*merge_bvec_fn;
>  	softirq_done_fn		*softirq_done_fn;
>  	rq_timed_out_fn		*rq_timed_out_fn;
>  	dma_drain_needed_fn	*dma_drain_needed;
> @@ -1041,7 +1032,6 @@ extern void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn);
>  extern void blk_queue_segment_boundary(struct request_queue *, unsigned long);
>  extern void blk_queue_prep_rq(struct request_queue *, prep_rq_fn *pfn);
>  extern void blk_queue_unprep_rq(struct request_queue *, unprep_rq_fn *ufn);
> -extern void blk_queue_merge_bvec(struct request_queue *, merge_bvec_fn *);
>  extern void blk_queue_dma_alignment(struct request_queue *, int);
>  extern void blk_queue_update_dma_alignment(struct request_queue *, int);
>  extern void blk_queue_softirq_done(struct request_queue *, softirq_done_fn *);
> diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
> index 51cc1de..76d23fa 100644
> --- a/include/linux/device-mapper.h
> +++ b/include/linux/device-mapper.h
> @@ -82,9 +82,6 @@ typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
>  typedef int (*dm_ioctl_fn) (struct dm_target *ti, unsigned int cmd,
>  			    unsigned long arg);
>  
> -typedef int (*dm_merge_fn) (struct dm_target *ti, struct bvec_merge_data *bvm,
> -			    struct bio_vec *biovec, int max_size);
> -
>  /*
>   * These iteration functions are typically used to check (and combine)
>   * properties of underlying devices.
> @@ -160,7 +157,6 @@ struct target_type {
>  	dm_status_fn status;
>  	dm_message_fn message;
>  	dm_ioctl_fn ioctl;
> -	dm_merge_fn merge;
>  	dm_busy_fn busy;
>  	dm_iterate_devices_fn iterate_devices;
>  	dm_io_hints_fn io_hints;

Christoph Hellwig May 25, 2015, 2:04 p.m. UTC | #2

On Fri, May 22, 2015 at 11:18:40AM -0700, Ming Lin wrote:
> From: Kent Overstreet <[e-mail]>
> 
> As generic_make_request() is now able to handle arbitrarily sized bios,
> it's no longer necessary for each individual block driver to define its
> own ->merge_bvec_fn() callback. Remove every invocation completely.

It might be good to replace patch 1 and this one by a patch per driver
to remove the merge_bvec_fn instance and add the blk_queue_split call
for all those drivers that actually had a ->merge_bvec_fn.  As some
of them were non-trivial attention from the maintainers would be helpful,
and a patch per driver might help with that.

> -/* This is called by bio_add_page().
> - *
> - * q->max_hw_sectors and other global limits are already enforced there.
> - *
> - * We need to call down to our lower level device,
> - * in case it has special restrictions.
> - *
> - * We also may need to enforce configured max-bio-bvecs limits.
> - *
> - * As long as the BIO is empty we have to allow at least one bvec,
> - * regardless of size and offset, so no need to ask lower levels.
> - */
> -int drbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct bio_vec *bvec)


This just checks the lower device, so it looks obviously fine.

> -static int pkt_merge_bvec(struct request_queue *q, struct bvec_merge_data *bmd,
> -			  struct bio_vec *bvec)
> -{
> -	struct pktcdvd_device *pd = q->queuedata;
> -	sector_t zone = get_zone(bmd->bi_sector, pd);
> -	int used = ((bmd->bi_sector - zone) << 9) + bmd->bi_size;
> -	int remaining = (pd->settings.size << 9) - used;
> -	int remaining2;
> -
> -	/*
> -	 * A bio <= PAGE_SIZE must be allowed. If it crosses a packet
> -	 * boundary, pkt_make_request() will split the bio.
> -	 */
> -	remaining2 = PAGE_SIZE - bmd->bi_size;
> -	remaining = max(remaining, remaining2);
> -
> -	BUG_ON(remaining < 0);
> -	return remaining;
> -}

As mentioned in the comment pkt_make_request will split the bio so pkt
looks fine.

> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index ec6c5c6..f50edb3 100644
> --- a/drivers/block/rbd.c
> +++ b/drivers/block/rbd.c
> @@ -3440,52 +3440,6 @@ static int rbd_queue_rq(struct blk_mq_hw_ctx *hctx,
>  	return BLK_MQ_RQ_QUEUE_OK;
>  }
>  
> -/*
> - * a queue callback. Makes sure that we don't create a bio that spans across
> - * multiple osd objects. One exception would be with a single page bios,
> - * which we handle later at bio_chain_clone_range()
> - */
> -static int rbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bmd,
> -			  struct bio_vec *bvec)

It seems rbd handles requests spanning objects just fine, so I don't
really understand why rbd_merge_bvec even exists.  Getting some form
of ACK from the ceph folks would be useful.

> -/*
> - * We assume I/O is going to the origin (which is the volume
> - * more likely to have restrictions e.g. by being striped).
> - * (Looking up the exact location of the data would be expensive
> - * and could always be out of date by the time the bio is submitted.)
> - */
> -static int cache_bvec_merge(struct dm_target *ti,
> -			    struct bvec_merge_data *bvm,
> -			    struct bio_vec *biovec, int max_size)
> -{

DM seems to have the most complex merge functions of all drivers, so
I'd really love to see an ACK from Mike.

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Ilya Dryomov May 25, 2015, 3:02 p.m. UTC | #3

On Mon, May 25, 2015 at 5:04 PM, Christoph Hellwig <[e-mail]> wrote:
> On Fri, May 22, 2015 at 11:18:40AM -0700, Ming Lin wrote:
>> From: Kent Overstreet <[e-mail]>
>>
>> As generic_make_request() is now able to handle arbitrarily sized bios,
>> it's no longer necessary for each individual block driver to define its
>> own ->merge_bvec_fn() callback. Remove every invocation completely.
>
> It might be good to replace patch 1 and this one by a patch per driver
> to remove the merge_bvec_fn instance and add the blk_queue_split call
> for all those drivers that actually had a ->merge_bvec_fn.  As some
> of them were non-trivial attention from the maintainers would be helpful,
> and a patch per driver might help with that.
>
>> -/* This is called by bio_add_page().
>> - *
>> - * q->max_hw_sectors and other global limits are already enforced there.
>> - *
>> - * We need to call down to our lower level device,
>> - * in case it has special restrictions.
>> - *
>> - * We also may need to enforce configured max-bio-bvecs limits.
>> - *
>> - * As long as the BIO is empty we have to allow at least one bvec,
>> - * regardless of size and offset, so no need to ask lower levels.
>> - */
>> -int drbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct bio_vec *bvec)
>
>
> This just checks the lower device, so it looks obviously fine.
>
>> -static int pkt_merge_bvec(struct request_queue *q, struct bvec_merge_data *bmd,
>> -                       struct bio_vec *bvec)
>> -{
>> -     struct pktcdvd_device *pd = q->queuedata;
>> -     sector_t zone = get_zone(bmd->bi_sector, pd);
>> -     int used = ((bmd->bi_sector - zone) << 9) + bmd->bi_size;
>> -     int remaining = (pd->settings.size << 9) - used;
>> -     int remaining2;
>> -
>> -     /*
>> -      * A bio <= PAGE_SIZE must be allowed. If it crosses a packet
>> -      * boundary, pkt_make_request() will split the bio.
>> -      */
>> -     remaining2 = PAGE_SIZE - bmd->bi_size;
>> -     remaining = max(remaining, remaining2);
>> -
>> -     BUG_ON(remaining < 0);
>> -     return remaining;
>> -}
>
> As mentioned in the comment pkt_make_request will split the bio so pkt
> looks fine.
>
>> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
>> index ec6c5c6..f50edb3 100644
>> --- a/drivers/block/rbd.c
>> +++ b/drivers/block/rbd.c
>> @@ -3440,52 +3440,6 @@ static int rbd_queue_rq(struct blk_mq_hw_ctx *hctx,
>>       return BLK_MQ_RQ_QUEUE_OK;
>>  }
>>
>> -/*
>> - * a queue callback. Makes sure that we don't create a bio that spans across
>> - * multiple osd objects. One exception would be with a single page bios,
>> - * which we handle later at bio_chain_clone_range()
>> - */
>> -static int rbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bmd,
>> -                       struct bio_vec *bvec)
>
> It seems rbd handles requests spanning objects just fine, so I don't
> really understand why rbd_merge_bvec even exists.  Getting some form
> of ACK from the ceph folks would be useful.

I'm not Alex, but yeah, we have all the clone/split machinery and so we
can handle a spanning case just fine.  I think rbd_merge_bvec() exists
to make sure we don't have to do that unless it's really necessary -
like when a single page gets submitted at an inconvenient offset.

I have a patch that adds a blk_queue_chunk_sectors(object_size) call to
rbd_init_disk() but I haven't had a chance to play with it yet.  In any
case, we should be fine with getting rid of rbd_merge_bvec().  If this
ends up a per-driver patchset, I can make rbd_merge_bvec() ->
blk_queue_chunk_sectors() a single patch and push it through
ceph-client.git.

Thanks,

                Ilya
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Christoph Hellwig May 25, 2015, 3:08 p.m. UTC | #4

On Mon, May 25, 2015 at 06:02:30PM +0300, Ilya Dryomov wrote:
> I'm not Alex, but yeah, we have all the clone/split machinery and so we
> can handle a spanning case just fine.  I think rbd_merge_bvec() exists
> to make sure we don't have to do that unless it's really necessary -
> like when a single page gets submitted at an inconvenient offset.
> 
> I have a patch that adds a blk_queue_chunk_sectors(object_size) call to
> rbd_init_disk() but I haven't had a chance to play with it yet.  In any
> case, we should be fine with getting rid of rbd_merge_bvec().  If this
> ends up a per-driver patchset, I can make rbd_merge_bvec() ->
> blk_queue_chunk_sectors() a single patch and push it through
> ceph-client.git.

Hmm, looks like the new blk_queue_split_bio ignore the chunk_sectors
value, another thing that needs updating.  I forgot how many weird
merging hacks we had to add for nvme..

While I'd like to see per-driver patches we'd still need to merge
them together through the block tree.  Note that with this series
there won't be any benefit of using blk_queue_chunk_sectors over just
doing the split in rbd.  Maybe we can even remove it again and do
that work in the drivers in the future.
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Ilya Dryomov May 25, 2015, 3:19 p.m. UTC | #5

On Mon, May 25, 2015 at 6:08 PM, Christoph Hellwig <[e-mail]> wrote:
> On Mon, May 25, 2015 at 06:02:30PM +0300, Ilya Dryomov wrote:
>> I'm not Alex, but yeah, we have all the clone/split machinery and so we
>> can handle a spanning case just fine.  I think rbd_merge_bvec() exists
>> to make sure we don't have to do that unless it's really necessary -
>> like when a single page gets submitted at an inconvenient offset.
>>
>> I have a patch that adds a blk_queue_chunk_sectors(object_size) call to
>> rbd_init_disk() but I haven't had a chance to play with it yet.  In any
>> case, we should be fine with getting rid of rbd_merge_bvec().  If this
>> ends up a per-driver patchset, I can make rbd_merge_bvec() ->
>> blk_queue_chunk_sectors() a single patch and push it through
>> ceph-client.git.
>
> Hmm, looks like the new blk_queue_split_bio ignore the chunk_sectors
> value, another thing that needs updating.  I forgot how many weird
> merging hacks we had to add for nvme..
>
> While I'd like to see per-driver patches we'd still need to merge
> them together through the block tree.  Note that with this series
> there won't be any benefit of using blk_queue_chunk_sectors over just
> doing the split in rbd.  Maybe we can even remove it again and do
> that work in the drivers in the future.

OK, I'll drop it, especially if it's potentially on its way out.  With
the fancy striping support, which I'll hopefully get to sometime, the
striping pattern will become much more complicated anyway, so relying
on rbd doing bio splitting is right in the long run as well.

Thanks,

                Ilya
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Alex Elder May 25, 2015, 3:35 p.m. UTC | #6

On 05/25/2015 10:02 AM, Ilya Dryomov wrote:
> On Mon, May 25, 2015 at 5:04 PM, Christoph Hellwig <[e-mail]> wrote:
>> On Fri, May 22, 2015 at 11:18:40AM -0700, Ming Lin wrote:
>>> From: Kent Overstreet <[e-mail]>
>>>
>>> As generic_make_request() is now able to handle arbitrarily sized bios,
>>> it's no longer necessary for each individual block driver to define its
>>> own ->merge_bvec_fn() callback. Remove every invocation completely.
>>
>> It might be good to replace patch 1 and this one by a patch per driver
>> to remove the merge_bvec_fn instance and add the blk_queue_split call
>> for all those drivers that actually had a ->merge_bvec_fn.  As some
>> of them were non-trivial attention from the maintainers would be helpful,
>> and a patch per driver might help with that.
>>
>>> -/* This is called by bio_add_page().
>>> - *
>>> - * q->max_hw_sectors and other global limits are already enforced there.
>>> - *
>>> - * We need to call down to our lower level device,
>>> - * in case it has special restrictions.
>>> - *
>>> - * We also may need to enforce configured max-bio-bvecs limits.
>>> - *
>>> - * As long as the BIO is empty we have to allow at least one bvec,
>>> - * regardless of size and offset, so no need to ask lower levels.
>>> - */
>>> -int drbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct bio_vec *bvec)
>>
>>
>> This just checks the lower device, so it looks obviously fine.
>>
>>> -static int pkt_merge_bvec(struct request_queue *q, struct bvec_merge_data *bmd,
>>> -                       struct bio_vec *bvec)
>>> -{
>>> -     struct pktcdvd_device *pd = q->queuedata;
>>> -     sector_t zone = get_zone(bmd->bi_sector, pd);
>>> -     int used = ((bmd->bi_sector - zone) << 9) + bmd->bi_size;
>>> -     int remaining = (pd->settings.size << 9) - used;
>>> -     int remaining2;
>>> -
>>> -     /*
>>> -      * A bio <= PAGE_SIZE must be allowed. If it crosses a packet
>>> -      * boundary, pkt_make_request() will split the bio.
>>> -      */
>>> -     remaining2 = PAGE_SIZE - bmd->bi_size;
>>> -     remaining = max(remaining, remaining2);
>>> -
>>> -     BUG_ON(remaining < 0);
>>> -     return remaining;
>>> -}
>>
>> As mentioned in the comment pkt_make_request will split the bio so pkt
>> looks fine.
>>
>>> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
>>> index ec6c5c6..f50edb3 100644
>>> --- a/drivers/block/rbd.c
>>> +++ b/drivers/block/rbd.c
>>> @@ -3440,52 +3440,6 @@ static int rbd_queue_rq(struct blk_mq_hw_ctx *hctx,
>>>       return BLK_MQ_RQ_QUEUE_OK;
>>>  }
>>>
>>> -/*
>>> - * a queue callback. Makes sure that we don't create a bio that spans across
>>> - * multiple osd objects. One exception would be with a single page bios,
>>> - * which we handle later at bio_chain_clone_range()
>>> - */
>>> -static int rbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bmd,
>>> -                       struct bio_vec *bvec)
>>
>> It seems rbd handles requests spanning objects just fine, so I don't
>> really understand why rbd_merge_bvec even exists.  Getting some form
>> of ACK from the ceph folks would be useful.
> 
> I'm not Alex, but yeah, we have all the clone/split machinery and so we
> can handle a spanning case just fine.  I think rbd_merge_bvec() exists
> to make sure we don't have to do that unless it's really necessary -
> like when a single page gets submitted at an inconvenient offset.

I am Alex.  This is something I never removed.  I haven't
looked at it closely now, but it seems to me that after I
created a function that split stuff properly up *before*
the BIO layer got to it (which has since been replaced by
code related to Kent's immutable BIO work), there has been
no need for this function.  Removing this was on a long-ago
to-do list--but I didn't want to do it without spending some
time ensuring it wouldn't break anything.

If you want me to work through it in more detail so I can
give a more certain response, let me know and I will do so.

					-Alex

> I have a patch that adds a blk_queue_chunk_sectors(object_size) call to
> rbd_init_disk() but I haven't had a chance to play with it yet.  In any
> case, we should be fine with getting rid of rbd_merge_bvec().  If this
> ends up a per-driver patchset, I can make rbd_merge_bvec() ->
> blk_queue_chunk_sectors() a single patch and push it through
> ceph-client.git.
> 
> Thanks,
> 
>                 Ilya
> 

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Patch

diff --git a/block/blk-merge.c b/block/blk-merge.c
index dc14255..25cafb8 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -69,24 +69,13 @@  static struct bio *blk_bio_segment_split(struct request_queue *q,
 	struct bio *split;
 	struct bio_vec bv, bvprv;
 	struct bvec_iter iter;
-	unsigned seg_size = 0, nsegs = 0;
+	unsigned seg_size = 0, nsegs = 0, sectors = 0;
 	int prev = 0;
 
-	struct bvec_merge_data bvm = {
-		.bi_bdev	= bio->bi_bdev,
-		.bi_sector	= bio->bi_iter.bi_sector,
-		.bi_size	= 0,
-		.bi_rw		= bio->bi_rw,
-	};
-
 	bio_for_each_segment(bv, bio, iter) {
-		if (q->merge_bvec_fn &&
-		    q->merge_bvec_fn(q, &bvm, &bv) < (int) bv.bv_len)
-			goto split;
-
-		bvm.bi_size += bv.bv_len;
+		sectors += bv.bv_len >> 9;
 
-		if (bvm.bi_size >> 9 > queue_max_sectors(q))
+		if (sectors > queue_max_sectors(q))
 			goto split;
 
 		/*
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 12600bf..e90d477 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -53,28 +53,6 @@  void blk_queue_unprep_rq(struct request_queue *q, unprep_rq_fn *ufn)
 }
 EXPORT_SYMBOL(blk_queue_unprep_rq);
 
-/**
- * blk_queue_merge_bvec - set a merge_bvec function for queue
- * @q:		queue
- * @mbfn:	merge_bvec_fn
- *
- * Usually queues have static limitations on the max sectors or segments that
- * we can put in a request. Stacking drivers may have some settings that
- * are dynamic, and thus we have to query the queue whether it is ok to
- * add a new bio_vec to a bio at a given offset or not. If the block device
- * has such limitations, it needs to register a merge_bvec_fn to control
- * the size of bio's sent to it. Note that a block device *must* allow a
- * single page to be added to an empty bio. The block device driver may want
- * to use the bio_split() function to deal with these bio's. By default
- * no merge_bvec_fn is defined for a queue, and only the fixed limits are
- * honored.
- */
-void blk_queue_merge_bvec(struct request_queue *q, merge_bvec_fn *mbfn)
-{
-	q->merge_bvec_fn = mbfn;
-}
-EXPORT_SYMBOL(blk_queue_merge_bvec);
-
 void blk_queue_softirq_done(struct request_queue *q, softirq_done_fn *fn)
 {
 	q->softirq_done_fn = fn;
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index b905e98..63ce2b0 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -1449,7 +1449,6 @@  extern void do_submit(struct work_struct *ws);
 extern void __drbd_make_request(struct drbd_device *, struct bio *, unsigned long);
 extern void drbd_make_request(struct request_queue *q, struct bio *bio);
 extern int drbd_read_remote(struct drbd_device *device, struct drbd_request *req);
-extern int drbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct bio_vec *bvec);
 extern int is_valid_ar_handle(struct drbd_request *, sector_t);
 
 
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 81fde9e..771e68c 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -2774,7 +2774,6 @@  enum drbd_ret_code drbd_create_device(struct drbd_config_context *adm_ctx, unsig
 	   This triggers a max_bio_size message upon first attach or connect */
 	blk_queue_max_hw_sectors(q, DRBD_MAX_BIO_SIZE_SAFE >> 8);
 	blk_queue_bounce_limit(q, BLK_BOUNCE_ANY);
-	blk_queue_merge_bvec(q, drbd_merge_bvec);
 	q->queue_lock = &resource->req_lock;
 
 	device->md_io.page = alloc_page(GFP_KERNEL);
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index a6265bc..7523f00 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -1510,41 +1510,6 @@  void drbd_make_request(struct request_queue *q, struct bio *bio)
 	__drbd_make_request(device, bio, start_jif);
 }
 
-/* This is called by bio_add_page().
- *
- * q->max_hw_sectors and other global limits are already enforced there.
- *
- * We need to call down to our lower level device,
- * in case it has special restrictions.
- *
- * We also may need to enforce configured max-bio-bvecs limits.
- *
- * As long as the BIO is empty we have to allow at least one bvec,
- * regardless of size and offset, so no need to ask lower levels.
- */
-int drbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bvm, struct bio_vec *bvec)
-{
-	struct drbd_device *device = (struct drbd_device *) q->queuedata;
-	unsigned int bio_size = bvm->bi_size;
-	int limit = DRBD_MAX_BIO_SIZE;
-	int backing_limit;
-
-	if (bio_size && get_ldev(device)) {
-		unsigned int max_hw_sectors = queue_max_hw_sectors(q);
-		struct request_queue * const b =
-			device->ldev->backing_bdev->bd_disk->queue;
-		if (b->merge_bvec_fn) {
-			bvm->bi_bdev = device->ldev->backing_bdev;
-			backing_limit = b->merge_bvec_fn(b, bvm, bvec);
-			limit = min(limit, backing_limit);
-		}
-		put_ldev(device);
-		if ((limit >> 9) > max_hw_sectors)
-			limit = max_hw_sectors << 9;
-	}
-	return limit;
-}
-
 void request_timer_fn(unsigned long data)
 {
 	struct drbd_device *device = (struct drbd_device *) data;
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index ea10bd9..85eac23 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -2505,26 +2505,6 @@  end_io:
 
 
 
-static int pkt_merge_bvec(struct request_queue *q, struct bvec_merge_data *bmd,
-			  struct bio_vec *bvec)
-{
-	struct pktcdvd_device *pd = q->queuedata;
-	sector_t zone = get_zone(bmd->bi_sector, pd);
-	int used = ((bmd->bi_sector - zone) << 9) + bmd->bi_size;
-	int remaining = (pd->settings.size << 9) - used;
-	int remaining2;
-
-	/*
-	 * A bio <= PAGE_SIZE must be allowed. If it crosses a packet
-	 * boundary, pkt_make_request() will split the bio.
-	 */
-	remaining2 = PAGE_SIZE - bmd->bi_size;
-	remaining = max(remaining, remaining2);
-
-	BUG_ON(remaining < 0);
-	return remaining;
-}
-
 static void pkt_init_queue(struct pktcdvd_device *pd)
 {
 	struct request_queue *q = pd->disk->queue;
@@ -2532,7 +2512,6 @@  static void pkt_init_queue(struct pktcdvd_device *pd)
 	blk_queue_make_request(q, pkt_make_request);
 	blk_queue_logical_block_size(q, CD_FRAMESIZE);
 	blk_queue_max_hw_sectors(q, PACKET_MAX_SECTORS);
-	blk_queue_merge_bvec(q, pkt_merge_bvec);
 	q->queuedata = pd;
 }
 
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index ec6c5c6..f50edb3 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -3440,52 +3440,6 @@  static int rbd_queue_rq(struct blk_mq_hw_ctx *hctx,
 	return BLK_MQ_RQ_QUEUE_OK;
 }
 
-/*
- * a queue callback. Makes sure that we don't create a bio that spans across
- * multiple osd objects. One exception would be with a single page bios,
- * which we handle later at bio_chain_clone_range()
- */
-static int rbd_merge_bvec(struct request_queue *q, struct bvec_merge_data *bmd,
-			  struct bio_vec *bvec)
-{
-	struct rbd_device *rbd_dev = q->queuedata;
-	sector_t sector_offset;
-	sector_t sectors_per_obj;
-	sector_t obj_sector_offset;
-	int ret;
-
-	/*
-	 * Find how far into its rbd object the partition-relative
-	 * bio start sector is to offset relative to the enclosing
-	 * device.
-	 */
-	sector_offset = get_start_sect(bmd->bi_bdev) + bmd->bi_sector;
-	sectors_per_obj = 1 << (rbd_dev->header.obj_order - SECTOR_SHIFT);
-	obj_sector_offset = sector_offset & (sectors_per_obj - 1);
-
-	/*
-	 * Compute the number of bytes from that offset to the end
-	 * of the object.  Account for what's already used by the bio.
-	 */
-	ret = (int) (sectors_per_obj - obj_sector_offset) << SECTOR_SHIFT;
-	if (ret > bmd->bi_size)
-		ret -= bmd->bi_size;
-	else
-		ret = 0;
-
-	/*
-	 * Don't send back more than was asked for.  And if the bio
-	 * was empty, let the whole thing through because:  "Note
-	 * that a block device *must* allow a single page to be
-	 * added to an empty bio."
-	 */
-	rbd_assert(bvec->bv_len <= PAGE_SIZE);
-	if (ret > (int) bvec->bv_len || !bmd->bi_size)
-		ret = (int) bvec->bv_len;
-
-	return ret;
-}
-
 static void rbd_free_disk(struct rbd_device *rbd_dev)
 {
 	struct gendisk *disk = rbd_dev->disk;
@@ -3784,7 +3738,6 @@  static int rbd_init_disk(struct rbd_device *rbd_dev)
 	q->limits.max_discard_sectors = segment_size / SECTOR_SIZE;
 	q->limits.discard_zeroes_data = 1;
 
-	blk_queue_merge_bvec(q, rbd_merge_bvec);
 	disk->queue = q;
 
 	q->queuedata = rbd_dev;
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 7755af3..2e47e35 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -3289,26 +3289,6 @@  static int cache_iterate_devices(struct dm_target *ti,
 	return r;
 }
 
-/*
- * We assume I/O is going to the origin (which is the volume
- * more likely to have restrictions e.g. by being striped).
- * (Looking up the exact location of the data would be expensive
- * and could always be out of date by the time the bio is submitted.)
- */
-static int cache_bvec_merge(struct dm_target *ti,
-			    struct bvec_merge_data *bvm,
-			    struct bio_vec *biovec, int max_size)
-{
-	struct cache *cache = ti->private;
-	struct request_queue *q = bdev_get_queue(cache->origin_dev->bdev);
-
-	if (!q->merge_bvec_fn)
-		return max_size;
-
-	bvm->bi_bdev = cache->origin_dev->bdev;
-	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
-}
-
 static void set_discard_limits(struct cache *cache, struct queue_limits *limits)
 {
 	/*
@@ -3352,7 +3332,6 @@  static struct target_type cache_target = {
 	.status = cache_status,
 	.message = cache_message,
 	.iterate_devices = cache_iterate_devices,
-	.merge = cache_bvec_merge,
 	.io_hints = cache_io_hints,
 };
 
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 5503e43..d13f330 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -2017,21 +2017,6 @@  error:
 	return -EINVAL;
 }
 
-static int crypt_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
-		       struct bio_vec *biovec, int max_size)
-{
-	struct crypt_config *cc = ti->private;
-	struct request_queue *q = bdev_get_queue(cc->dev->bdev);
-
-	if (!q->merge_bvec_fn)
-		return max_size;
-
-	bvm->bi_bdev = cc->dev->bdev;
-	bvm->bi_sector = cc->start + dm_target_offset(ti, bvm->bi_sector);
-
-	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
-}
-
 static int crypt_iterate_devices(struct dm_target *ti,
 				 iterate_devices_callout_fn fn, void *data)
 {
@@ -2052,7 +2037,6 @@  static struct target_type crypt_target = {
 	.preresume = crypt_preresume,
 	.resume = crypt_resume,
 	.message = crypt_message,
-	.merge  = crypt_merge,
 	.iterate_devices = crypt_iterate_devices,
 };
 
diff --git a/drivers/md/dm-era-target.c b/drivers/md/dm-era-target.c
index ad913cd..0119ebf 100644
--- a/drivers/md/dm-era-target.c
+++ b/drivers/md/dm-era-target.c
@@ -1673,20 +1673,6 @@  static int era_iterate_devices(struct dm_target *ti,
 	return fn(ti, era->origin_dev, 0, get_dev_size(era->origin_dev), data);
 }
 
-static int era_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
-		     struct bio_vec *biovec, int max_size)
-{
-	struct era *era = ti->private;
-	struct request_queue *q = bdev_get_queue(era->origin_dev->bdev);
-
-	if (!q->merge_bvec_fn)
-		return max_size;
-
-	bvm->bi_bdev = era->origin_dev->bdev;
-
-	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
-}
-
 static void era_io_hints(struct dm_target *ti, struct queue_limits *limits)
 {
 	struct era *era = ti->private;
@@ -1717,7 +1703,6 @@  static struct target_type era_target = {
 	.status = era_status,
 	.message = era_message,
 	.iterate_devices = era_iterate_devices,
-	.merge = era_merge,
 	.io_hints = era_io_hints
 };
 
diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c
index b257e46..d955b3e 100644
--- a/drivers/md/dm-flakey.c
+++ b/drivers/md/dm-flakey.c
@@ -387,21 +387,6 @@  static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long ar
 	return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
 }
 
-static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
-			struct bio_vec *biovec, int max_size)
-{
-	struct flakey_c *fc = ti->private;
-	struct request_queue *q = bdev_get_queue(fc->dev->bdev);
-
-	if (!q->merge_bvec_fn)
-		return max_size;
-
-	bvm->bi_bdev = fc->dev->bdev;
-	bvm->bi_sector = flakey_map_sector(ti, bvm->bi_sector);
-
-	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
-}
-
 static int flakey_iterate_devices(struct dm_target *ti, iterate_devices_callout_fn fn, void *data)
 {
 	struct flakey_c *fc = ti->private;
@@ -419,7 +404,6 @@  static struct target_type flakey_target = {
 	.end_io = flakey_end_io,
 	.status = flakey_status,
 	.ioctl	= flakey_ioctl,
-	.merge	= flakey_merge,
 	.iterate_devices = flakey_iterate_devices,
 };
 
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 53e848c..7dd5fc8 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -130,21 +130,6 @@  static int linear_ioctl(struct dm_target *ti, unsigned int cmd,
 	return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
 }
 
-static int linear_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
-			struct bio_vec *biovec, int max_size)
-{
-	struct linear_c *lc = ti->private;
-	struct request_queue *q = bdev_get_queue(lc->dev->bdev);
-
-	if (!q->merge_bvec_fn)
-		return max_size;
-
-	bvm->bi_bdev = lc->dev->bdev;
-	bvm->bi_sector = linear_map_sector(ti, bvm->bi_sector);
-
-	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
-}
-
 static int linear_iterate_devices(struct dm_target *ti,
 				  iterate_devices_callout_fn fn, void *data)
 {
@@ -162,7 +147,6 @@  static struct target_type linear_target = {
 	.map    = linear_map,
 	.status = linear_status,
 	.ioctl  = linear_ioctl,
-	.merge  = linear_merge,
 	.iterate_devices = linear_iterate_devices,
 };
 
diff --git a/drivers/md/dm-log-writes.c b/drivers/md/dm-log-writes.c
index 93e0844..4325808 100644
--- a/drivers/md/dm-log-writes.c
+++ b/drivers/md/dm-log-writes.c
@@ -728,21 +728,6 @@  static int log_writes_ioctl(struct dm_target *ti, unsigned int cmd,
 	return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
 }
 
-static int log_writes_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
-			    struct bio_vec *biovec, int max_size)
-{
-	struct log_writes_c *lc = ti->private;
-	struct request_queue *q = bdev_get_queue(lc->dev->bdev);
-
-	if (!q->merge_bvec_fn)
-		return max_size;
-
-	bvm->bi_bdev = lc->dev->bdev;
-	bvm->bi_sector = dm_target_offset(ti, bvm->bi_sector);
-
-	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
-}
-
 static int log_writes_iterate_devices(struct dm_target *ti,
 				      iterate_devices_callout_fn fn,
 				      void *data)
@@ -796,7 +781,6 @@  static struct target_type log_writes_target = {
 	.end_io = normal_end_io,
 	.status = log_writes_status,
 	.ioctl	= log_writes_ioctl,
-	.merge	= log_writes_merge,
 	.message = log_writes_message,
 	.iterate_devices = log_writes_iterate_devices,
 	.io_hints = log_writes_io_hints,
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index f83a0f3..274cbec 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -2331,20 +2331,6 @@  static void origin_status(struct dm_target *ti, status_type_t type,
 	}
 }
 
-static int origin_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
-			struct bio_vec *biovec, int max_size)
-{
-	struct dm_origin *o = ti->private;
-	struct request_queue *q = bdev_get_queue(o->dev->bdev);
-
-	if (!q->merge_bvec_fn)
-		return max_size;
-
-	bvm->bi_bdev = o->dev->bdev;
-
-	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
-}
-
 static int origin_iterate_devices(struct dm_target *ti,
 				  iterate_devices_callout_fn fn, void *data)
 {
@@ -2363,7 +2349,6 @@  static struct target_type origin_target = {
 	.resume  = origin_resume,
 	.postsuspend = origin_postsuspend,
 	.status  = origin_status,
-	.merge	 = origin_merge,
 	.iterate_devices = origin_iterate_devices,
 };
 
diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index f8b37d4..09bb2fe 100644
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -412,26 +412,6 @@  static void stripe_io_hints(struct dm_target *ti,
 	blk_limits_io_opt(limits, chunk_size * sc->stripes);
 }
 
-static int stripe_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
-			struct bio_vec *biovec, int max_size)
-{
-	struct stripe_c *sc = ti->private;
-	sector_t bvm_sector = bvm->bi_sector;
-	uint32_t stripe;
-	struct request_queue *q;
-
-	stripe_map_sector(sc, bvm_sector, &stripe, &bvm_sector);
-
-	q = bdev_get_queue(sc->stripe[stripe].dev->bdev);
-	if (!q->merge_bvec_fn)
-		return max_size;
-
-	bvm->bi_bdev = sc->stripe[stripe].dev->bdev;
-	bvm->bi_sector = sc->stripe[stripe].physical_start + bvm_sector;
-
-	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
-}
-
 static struct target_type stripe_target = {
 	.name   = "striped",
 	.version = {1, 5, 1},
@@ -443,7 +423,6 @@  static struct target_type stripe_target = {
 	.status = stripe_status,
 	.iterate_devices = stripe_iterate_devices,
 	.io_hints = stripe_io_hints,
-	.merge  = stripe_merge,
 };
 
 int __init dm_stripe_init(void)
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index d9b00b8..19c9b01 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -440,14 +440,6 @@  static int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
 		       q->limits.alignment_offset,
 		       (unsigned long long) start << SECTOR_SHIFT);
 
-	/*
-	 * Check if merge fn is supported.
-	 * If not we'll force DM to use PAGE_SIZE or
-	 * smaller I/O, just to be safe.
-	 */
-	if (dm_queue_merge_is_compulsory(q) && !ti->type->merge)
-		blk_limits_max_hw_sectors(limits,
-					  (unsigned int) (PAGE_SIZE >> 9));
 	return 0;
 }
 
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 921aafd..03552fe 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -3562,20 +3562,6 @@  static int pool_iterate_devices(struct dm_target *ti,
 	return fn(ti, pt->data_dev, 0, ti->len, data);
 }
 
-static int pool_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
-		      struct bio_vec *biovec, int max_size)
-{
-	struct pool_c *pt = ti->private;
-	struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);
-
-	if (!q->merge_bvec_fn)
-		return max_size;
-
-	bvm->bi_bdev = pt->data_dev->bdev;
-
-	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
-}
-
 static void set_discard_limits(struct pool_c *pt, struct queue_limits *limits)
 {
 	struct pool *pool = pt->pool;
@@ -3667,7 +3653,6 @@  static struct target_type pool_target = {
 	.resume = pool_resume,
 	.message = pool_message,
 	.status = pool_status,
-	.merge = pool_merge,
 	.iterate_devices = pool_iterate_devices,
 	.io_hints = pool_io_hints,
 };
@@ -3992,21 +3977,6 @@  err:
 	DMEMIT("Error");
 }
 
-static int thin_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
-		      struct bio_vec *biovec, int max_size)
-{
-	struct thin_c *tc = ti->private;
-	struct request_queue *q = bdev_get_queue(tc->pool_dev->bdev);
-
-	if (!q->merge_bvec_fn)
-		return max_size;
-
-	bvm->bi_bdev = tc->pool_dev->bdev;
-	bvm->bi_sector = dm_target_offset(ti, bvm->bi_sector);
-
-	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
-}
-
 static int thin_iterate_devices(struct dm_target *ti,
 				iterate_devices_callout_fn fn, void *data)
 {
@@ -4041,7 +4011,6 @@  static struct target_type thin_target = {
 	.presuspend = thin_presuspend,
 	.postsuspend = thin_postsuspend,
 	.status = thin_status,
-	.merge = thin_merge,
 	.iterate_devices = thin_iterate_devices,
 };
 
diff --git a/drivers/md/dm-verity.c b/drivers/md/dm-verity.c
index 66616db..3b85460 100644
--- a/drivers/md/dm-verity.c
+++ b/drivers/md/dm-verity.c
@@ -648,21 +648,6 @@  static int verity_ioctl(struct dm_target *ti, unsigned cmd,
 				     cmd, arg);
 }
 
-static int verity_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
-			struct bio_vec *biovec, int max_size)
-{
-	struct dm_verity *v = ti->private;
-	struct request_queue *q = bdev_get_queue(v->data_dev->bdev);
-
-	if (!q->merge_bvec_fn)
-		return max_size;
-
-	bvm->bi_bdev = v->data_dev->bdev;
-	bvm->bi_sector = verity_map_sector(v, bvm->bi_sector);
-
-	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
-}
-
 static int verity_iterate_devices(struct dm_target *ti,
 				  iterate_devices_callout_fn fn, void *data)
 {
@@ -995,7 +980,6 @@  static struct target_type verity_target = {
 	.map		= verity_map,
 	.status		= verity_status,
 	.ioctl		= verity_ioctl,
-	.merge		= verity_merge,
 	.iterate_devices = verity_iterate_devices,
 	.io_hints	= verity_io_hints,
 };
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 34f6063..f732a7a 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -121,9 +121,8 @@  EXPORT_SYMBOL_GPL(dm_get_rq_mapinfo);
 #define DMF_FREEING 3
 #define DMF_DELETING 4
 #define DMF_NOFLUSH_SUSPENDING 5
-#define DMF_MERGE_IS_OPTIONAL 6
-#define DMF_DEFERRED_REMOVE 7
-#define DMF_SUSPENDED_INTERNALLY 8
+#define DMF_DEFERRED_REMOVE 6
+#define DMF_SUSPENDED_INTERNALLY 7
 
 /*
  * A dummy definition to make RCU happy.
@@ -1717,60 +1716,6 @@  static void __split_and_process_bio(struct mapped_device *md,
  * CRUD END
  *---------------------------------------------------------------*/
 
-static int dm_merge_bvec(struct request_queue *q,
-			 struct bvec_merge_data *bvm,
-			 struct bio_vec *biovec)
-{
-	struct mapped_device *md = q->queuedata;
-	struct dm_table *map = dm_get_live_table_fast(md);
-	struct dm_target *ti;
-	sector_t max_sectors;
-	int max_size = 0;
-
-	if (unlikely(!map))
-		goto out;
-
-	ti = dm_table_find_target(map, bvm->bi_sector);
-	if (!dm_target_is_valid(ti))
-		goto out;
-
-	/*
-	 * Find maximum amount of I/O that won't need splitting
-	 */
-	max_sectors = min(max_io_len(bvm->bi_sector, ti),
-			  (sector_t) queue_max_sectors(q));
-	max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size;
-	if (unlikely(max_size < 0)) /* this shouldn't _ever_ happen */
-		max_size = 0;
-
-	/*
-	 * merge_bvec_fn() returns number of bytes
-	 * it can accept at this offset
-	 * max is precomputed maximal io size
-	 */
-	if (max_size && ti->type->merge)
-		max_size = ti->type->merge(ti, bvm, biovec, max_size);
-	/*
-	 * If the target doesn't support merge method and some of the devices
-	 * provided their merge_bvec method (we know this by looking for the
-	 * max_hw_sectors that dm_set_device_limits may set), then we can't
-	 * allow bios with multiple vector entries.  So always set max_size
-	 * to 0, and the code below allows just one page.
-	 */
-	else if (queue_max_hw_sectors(q) <= PAGE_SIZE >> 9)
-		max_size = 0;
-
-out:
-	dm_put_live_table_fast(md);
-	/*
-	 * Always allow an entire first page
-	 */
-	if (max_size <= biovec->bv_len && !(bvm->bi_size >> SECTOR_SHIFT))
-		max_size = biovec->bv_len;
-
-	return max_size;
-}
-
 /*
  * The request function that just remaps the bio built up by
  * dm_merge_bvec.
@@ -2477,59 +2422,6 @@  static void __set_size(struct mapped_device *md, sector_t size)
 }
 
 /*
- * Return 1 if the queue has a compulsory merge_bvec_fn function.
- *
- * If this function returns 0, then the device is either a non-dm
- * device without a merge_bvec_fn, or it is a dm device that is
- * able to split any bios it receives that are too big.
- */
-int dm_queue_merge_is_compulsory(struct request_queue *q)
-{
-	struct mapped_device *dev_md;
-
-	if (!q->merge_bvec_fn)
-		return 0;
-
-	if (q->make_request_fn == dm_make_request) {
-		dev_md = q->queuedata;
-		if (test_bit(DMF_MERGE_IS_OPTIONAL, &dev_md->flags))
-			return 0;
-	}
-
-	return 1;
-}
-
-static int dm_device_merge_is_compulsory(struct dm_target *ti,
-					 struct dm_dev *dev, sector_t start,
-					 sector_t len, void *data)
-{
-	struct block_device *bdev = dev->bdev;
-	struct request_queue *q = bdev_get_queue(bdev);
-
-	return dm_queue_merge_is_compulsory(q);
-}
-
-/*
- * Return 1 if it is acceptable to ignore merge_bvec_fn based
- * on the properties of the underlying devices.
- */
-static int dm_table_merge_is_optional(struct dm_table *table)
-{
-	unsigned i = 0;
-	struct dm_target *ti;
-
-	while (i < dm_table_get_num_targets(table)) {
-		ti = dm_table_get_target(table, i++);
-
-		if (ti->type->iterate_devices &&
-		    ti->type->iterate_devices(ti, dm_device_merge_is_compulsory, NULL))
-			return 0;
-	}
-
-	return 1;
-}
-
-/*
  * Returns old map, which caller must destroy.
  */
 static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
@@ -2538,7 +2430,6 @@  static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
 	struct dm_table *old_map;
 	struct request_queue *q = md->queue;
 	sector_t size;
-	int merge_is_optional;
 
 	size = dm_table_get_size(t);
 
@@ -2564,17 +2455,11 @@  static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
 
 	__bind_mempools(md, t);
 
-	merge_is_optional = dm_table_merge_is_optional(t);
-
 	old_map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock));
 	rcu_assign_pointer(md->map, t);
 	md->immutable_target_type = dm_table_get_immutable_target_type(t);
 
 	dm_table_set_restrictions(t, q, limits);
-	if (merge_is_optional)
-		set_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
-	else
-		clear_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
 	if (old_map)
 		dm_sync_table(md);
 
@@ -2852,7 +2737,6 @@  int dm_setup_md_queue(struct mapped_device *md)
 	case DM_TYPE_BIO_BASED:
 		dm_init_old_md_queue(md);
 		blk_queue_make_request(md->queue, dm_make_request);
-		blk_queue_merge_bvec(md->queue, dm_merge_bvec);
 		break;
 	}
 
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 6123c2b..7d61cca 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -77,8 +77,6 @@  bool dm_table_mq_request_based(struct dm_table *t);
 void dm_table_free_md_mempools(struct dm_table *t);
 struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t);
 
-int dm_queue_merge_is_compulsory(struct request_queue *q);
-
 void dm_lock_md_type(struct mapped_device *md);
 void dm_unlock_md_type(struct mapped_device *md);
 void dm_set_md_type(struct mapped_device *md, unsigned type);
diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index fa7d577..8721ef9 100644
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -52,48 +52,6 @@  static inline struct dev_info *which_dev(struct mddev *mddev, sector_t sector)
 	return conf->disks + lo;
 }
 
-/**
- *	linear_mergeable_bvec -- tell bio layer if two requests can be merged
- *	@q: request queue
- *	@bvm: properties of new bio
- *	@biovec: the request that could be merged to it.
- *
- *	Return amount of bytes we can take at this offset
- */
-static int linear_mergeable_bvec(struct mddev *mddev,
-				 struct bvec_merge_data *bvm,
-				 struct bio_vec *biovec)
-{
-	struct dev_info *dev0;
-	unsigned long maxsectors, bio_sectors = bvm->bi_size >> 9;
-	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
-	int maxbytes = biovec->bv_len;
-	struct request_queue *subq;
-
-	dev0 = which_dev(mddev, sector);
-	maxsectors = dev0->end_sector - sector;
-	subq = bdev_get_queue(dev0->rdev->bdev);
-	if (subq->merge_bvec_fn) {
-		bvm->bi_bdev = dev0->rdev->bdev;
-		bvm->bi_sector -= dev0->end_sector - dev0->rdev->sectors;
-		maxbytes = min(maxbytes, subq->merge_bvec_fn(subq, bvm,
-							     biovec));
-	}
-
-	if (maxsectors < bio_sectors)
-		maxsectors = 0;
-	else
-		maxsectors -= bio_sectors;
-
-	if (maxsectors <= (PAGE_SIZE >> 9 ) && bio_sectors == 0)
-		return maxbytes;
-
-	if (maxsectors > (maxbytes >> 9))
-		return maxbytes;
-	else
-		return maxsectors << 9;
-}
-
 static int linear_congested(struct mddev *mddev, int bits)
 {
 	struct linear_conf *conf;
@@ -338,7 +296,6 @@  static struct md_personality linear_personality =
 	.size		= linear_size,
 	.quiesce	= linear_quiesce,
 	.congested	= linear_congested,
-	.mergeable_bvec	= linear_mergeable_bvec,
 };
 
 static int __init linear_init (void)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 046b3c9..f101981 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -352,29 +352,6 @@  static int md_congested(void *data, int bits)
 	return mddev_congested(mddev, bits);
 }
 
-static int md_mergeable_bvec(struct request_queue *q,
-			     struct bvec_merge_data *bvm,
-			     struct bio_vec *biovec)
-{
-	struct mddev *mddev = q->queuedata;
-	int ret;
-	rcu_read_lock();
-	if (mddev->suspended) {
-		/* Must always allow one vec */
-		if (bvm->bi_size == 0)
-			ret = biovec->bv_len;
-		else
-			ret = 0;
-	} else {
-		struct md_personality *pers = mddev->pers;
-		if (pers && pers->mergeable_bvec)
-			ret = pers->mergeable_bvec(mddev, bvm, biovec);
-		else
-			ret = biovec->bv_len;
-	}
-	rcu_read_unlock();
-	return ret;
-}
 /*
  * Generic flush handling for md
  */
@@ -5165,7 +5142,6 @@  int md_run(struct mddev *mddev)
 	if (mddev->queue) {
 		mddev->queue->backing_dev_info.congested_data = mddev;
 		mddev->queue->backing_dev_info.congested_fn = md_congested;
-		blk_queue_merge_bvec(mddev->queue, md_mergeable_bvec);
 	}
 	if (pers->sync_request) {
 		if (mddev->kobj.sd &&
@@ -5293,7 +5269,6 @@  static void md_clean(struct mddev *mddev)
 	mddev->changed = 0;
 	mddev->degraded = 0;
 	mddev->safemode = 0;
-	mddev->merge_check_needed = 0;
 	mddev->bitmap_info.offset = 0;
 	mddev->bitmap_info.default_offset = 0;
 	mddev->bitmap_info.default_space = 0;
@@ -5489,7 +5464,6 @@  static int do_md_stop(struct mddev *mddev, int mode,
 
 		__md_stop_writes(mddev);
 		__md_stop(mddev);
-		mddev->queue->merge_bvec_fn = NULL;
 		mddev->queue->backing_dev_info.congested_fn = NULL;
 
 		/* tell userspace to handle 'inactive' */
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 4046a6c..cf7141a 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -133,10 +133,6 @@  enum flag_bits {
 	Bitmap_sync,		/* ..actually, not quite In_sync.  Need a
 				 * bitmap-based recovery to get fully in sync
 				 */
-	Unmerged,		/* device is being added to array and should
-				 * be considerred for bvec_merge_fn but not
-				 * yet for actual IO
-				 */
 	WriteMostly,		/* Avoid reading if at all possible */
 	AutoDetected,		/* added by auto-detect */
 	Blocked,		/* An error occurred but has not yet
@@ -373,10 +369,6 @@  struct mddev {
 	int				degraded;	/* whether md should consider
 							 * adding a spare
 							 */
-	int				merge_check_needed; /* at least one
-							     * member device
-							     * has a
-							     * merge_bvec_fn */
 
 	atomic_t			recovery_active; /* blocks scheduled, but not written */
 	wait_queue_head_t		recovery_wait;
@@ -531,10 +523,6 @@  struct md_personality
 	/* congested implements bdi.congested_fn().
 	 * Will not be called while array is 'suspended' */
 	int (*congested)(struct mddev *mddev, int bits);
-	/* mergeable_bvec is use to implement ->merge_bvec_fn */
-	int (*mergeable_bvec)(struct mddev *mddev,
-			      struct bvec_merge_data *bvm,
-			      struct bio_vec *biovec);
 };
 
 struct md_sysfs_entry {
diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c
index ac3ede2..7ee27fb 100644
--- a/drivers/md/multipath.c
+++ b/drivers/md/multipath.c
@@ -257,18 +257,6 @@  static int multipath_add_disk(struct mddev *mddev, struct md_rdev *rdev)
 			disk_stack_limits(mddev->gendisk, rdev->bdev,
 					  rdev->data_offset << 9);
 
-		/* as we don't honour merge_bvec_fn, we must never risk
-		 * violating it, so limit ->max_segments to one, lying
-		 * within a single page.
-		 * (Note: it is very unlikely that a device with
-		 * merge_bvec_fn will be involved in multipath.)
-		 */
-			if (q->merge_bvec_fn) {
-				blk_queue_max_segments(mddev->queue, 1);
-				blk_queue_segment_boundary(mddev->queue,
-							   PAGE_CACHE_SIZE - 1);
-			}
-
 			spin_lock_irq(&conf->device_lock);
 			mddev->degraded--;
 			rdev->raid_disk = path;
@@ -432,15 +420,6 @@  static int multipath_run (struct mddev *mddev)
 		disk_stack_limits(mddev->gendisk, rdev->bdev,
 				  rdev->data_offset << 9);
 
-		/* as we don't honour merge_bvec_fn, we must never risk
-		 * violating it, not that we ever expect a device with
-		 * a merge_bvec_fn to be involved in multipath */
-		if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
-			blk_queue_max_segments(mddev->queue, 1);
-			blk_queue_segment_boundary(mddev->queue,
-						   PAGE_CACHE_SIZE - 1);
-		}
-
 		if (!test_bit(Faulty, &rdev->flags))
 			working_disks++;
 	}
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index 6a68ef5..1440bd4 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -192,9 +192,6 @@  static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
 			disk_stack_limits(mddev->gendisk, rdev1->bdev,
 					  rdev1->data_offset << 9);
 
-		if (rdev1->bdev->bd_disk->queue->merge_bvec_fn)
-			conf->has_merge_bvec = 1;
-
 		if (!smallest || (rdev1->sectors < smallest->sectors))
 			smallest = rdev1;
 		cnt++;
@@ -351,58 +348,6 @@  static struct md_rdev *map_sector(struct mddev *mddev, struct strip_zone *zone,
 			     + sector_div(sector, zone->nb_dev)];
 }
 
-/**
- *	raid0_mergeable_bvec -- tell bio layer if two requests can be merged
- *	@mddev: the md device
- *	@bvm: properties of new bio
- *	@biovec: the request that could be merged to it.
- *
- *	Return amount of bytes we can accept at this offset
- */
-static int raid0_mergeable_bvec(struct mddev *mddev,
-				struct bvec_merge_data *bvm,
-				struct bio_vec *biovec)
-{
-	struct r0conf *conf = mddev->private;
-	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
-	sector_t sector_offset = sector;
-	int max;
-	unsigned int chunk_sectors = mddev->chunk_sectors;
-	unsigned int bio_sectors = bvm->bi_size >> 9;
-	struct strip_zone *zone;
-	struct md_rdev *rdev;
-	struct request_queue *subq;
-
-	if (is_power_of_2(chunk_sectors))
-		max =  (chunk_sectors - ((sector & (chunk_sectors-1))
-						+ bio_sectors)) << 9;
-	else
-		max =  (chunk_sectors - (sector_div(sector, chunk_sectors)
-						+ bio_sectors)) << 9;
-	if (max < 0)
-		max = 0; /* bio_add cannot handle a negative return */
-	if (max <= biovec->bv_len && bio_sectors == 0)
-		return biovec->bv_len;
-	if (max < biovec->bv_len)
-		/* too small already, no need to check further */
-		return max;
-	if (!conf->has_merge_bvec)
-		return max;
-
-	/* May need to check subordinate device */
-	sector = sector_offset;
-	zone = find_zone(mddev->private, &sector_offset);
-	rdev = map_sector(mddev, zone, sector, &sector_offset);
-	subq = bdev_get_queue(rdev->bdev);
-	if (subq->merge_bvec_fn) {
-		bvm->bi_bdev = rdev->bdev;
-		bvm->bi_sector = sector_offset + zone->dev_start +
-			rdev->data_offset;
-		return min(max, subq->merge_bvec_fn(subq, bvm, biovec));
-	} else
-		return max;
-}
-
 static sector_t raid0_size(struct mddev *mddev, sector_t sectors, int raid_disks)
 {
 	sector_t array_sectors = 0;
@@ -725,7 +670,6 @@  static struct md_personality raid0_personality=
 	.takeover	= raid0_takeover,
 	.quiesce	= raid0_quiesce,
 	.congested	= raid0_congested,
-	.mergeable_bvec	= raid0_mergeable_bvec,
 };
 
 static int __init raid0_init (void)
diff --git a/drivers/md/raid0.h b/drivers/md/raid0.h
index 05539d9..7127a62 100644
--- a/drivers/md/raid0.h
+++ b/drivers/md/raid0.h
@@ -12,8 +12,6 @@  struct r0conf {
 	struct md_rdev		**devlist; /* lists of rdevs, pointed to
 					    * by strip_zone->dev */
 	int			nr_strip_zones;
-	int			has_merge_bvec;	/* at least one member has
-						 * a merge_bvec_fn */
 };
 
 #endif
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 9157a29..478878f 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -557,7 +557,6 @@  static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect
 		rdev = rcu_dereference(conf->mirrors[disk].rdev);
 		if (r1_bio->bios[disk] == IO_BLOCKED
 		    || rdev == NULL
-		    || test_bit(Unmerged, &rdev->flags)
 		    || test_bit(Faulty, &rdev->flags))
 			continue;
 		if (!test_bit(In_sync, &rdev->flags) &&
@@ -708,38 +707,6 @@  static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect
 	return best_disk;
 }
 
-static int raid1_mergeable_bvec(struct mddev *mddev,
-				struct bvec_merge_data *bvm,
-				struct bio_vec *biovec)
-{
-	struct r1conf *conf = mddev->private;
-	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
-	int max = biovec->bv_len;
-
-	if (mddev->merge_check_needed) {
-		int disk;
-		rcu_read_lock();
-		for (disk = 0; disk < conf->raid_disks * 2; disk++) {
-			struct md_rdev *rdev = rcu_dereference(
-				conf->mirrors[disk].rdev);
-			if (rdev && !test_bit(Faulty, &rdev->flags)) {
-				struct request_queue *q =
-					bdev_get_queue(rdev->bdev);
-				if (q->merge_bvec_fn) {
-					bvm->bi_sector = sector +
-						rdev->data_offset;
-					bvm->bi_bdev = rdev->bdev;
-					max = min(max, q->merge_bvec_fn(
-							  q, bvm, biovec));
-				}
-			}
-		}
-		rcu_read_unlock();
-	}
-	return max;
-
-}
-
 static int raid1_congested(struct mddev *mddev, int bits)
 {
 	struct r1conf *conf = mddev->private;
@@ -1268,8 +1235,7 @@  read_again:
 			break;
 		}
 		r1_bio->bios[i] = NULL;
-		if (!rdev || test_bit(Faulty, &rdev->flags)
-		    || test_bit(Unmerged, &rdev->flags)) {
+		if (!rdev || test_bit(Faulty, &rdev->flags)) {
 			if (i < conf->raid_disks)
 				set_bit(R1BIO_Degraded, &r1_bio->state);
 			continue;
@@ -1614,7 +1580,6 @@  static int raid1_add_disk(struct mddev *mddev, struct md_rdev *rdev)
 	struct raid1_info *p;
 	int first = 0;
 	int last = conf->raid_disks - 1;
-	struct request_queue *q = bdev_get_queue(rdev->bdev);
 
 	if (mddev->recovery_disabled == conf->recovery_disabled)
 		return -EBUSY;
@@ -1622,11 +1587,6 @@  static int raid1_add_disk(struct mddev *mddev, struct md_rdev *rdev)
 	if (rdev->raid_disk >= 0)
 		first = last = rdev->raid_disk;
 
-	if (q->merge_bvec_fn) {
-		set_bit(Unmerged, &rdev->flags);
-		mddev->merge_check_needed = 1;
-	}
-
 	for (mirror = first; mirror <= last; mirror++) {
 		p = conf->mirrors+mirror;
 		if (!p->rdev) {
@@ -1658,19 +1618,6 @@  static int raid1_add_disk(struct mddev *mddev, struct md_rdev *rdev)
 			break;
 		}
 	}
-	if (err == 0 && test_bit(Unmerged, &rdev->flags)) {
-		/* Some requests might not have seen this new
-		 * merge_bvec_fn.  We must wait for them to complete
-		 * before merging the device fully.
-		 * First we make sure any code which has tested
-		 * our function has submitted the request, then
-		 * we wait for all outstanding requests to complete.
-		 */
-		synchronize_sched();
-		freeze_array(conf, 0);
-		unfreeze_array(conf);
-		clear_bit(Unmerged, &rdev->flags);
-	}
 	md_integrity_add_rdev(rdev, mddev);
 	if (mddev->queue && blk_queue_discard(bdev_get_queue(rdev->bdev)))
 		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
@@ -2807,8 +2754,6 @@  static struct r1conf *setup_conf(struct mddev *mddev)
 			goto abort;
 		disk->rdev = rdev;
 		q = bdev_get_queue(rdev->bdev);
-		if (q->merge_bvec_fn)
-			mddev->merge_check_needed = 1;
 
 		disk->head_position = 0;
 		disk->seq_start = MaxSector;
@@ -3173,7 +3118,6 @@  static struct md_personality raid1_personality =
 	.quiesce	= raid1_quiesce,
 	.takeover	= raid1_takeover,
 	.congested	= raid1_congested,
-	.mergeable_bvec	= raid1_mergeable_bvec,
 };
 
 static int __init raid_init(void)
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index e793ab6..a46c402 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -672,93 +672,6 @@  static sector_t raid10_find_virt(struct r10conf *conf, sector_t sector, int dev)
 	return (vchunk << geo->chunk_shift) + offset;
 }
 
-/**
- *	raid10_mergeable_bvec -- tell bio layer if a two requests can be merged
- *	@mddev: the md device
- *	@bvm: properties of new bio
- *	@biovec: the request that could be merged to it.
- *
- *	Return amount of bytes we can accept at this offset
- *	This requires checking for end-of-chunk if near_copies != raid_disks,
- *	and for subordinate merge_bvec_fns if merge_check_needed.
- */
-static int raid10_mergeable_bvec(struct mddev *mddev,
-				 struct bvec_merge_data *bvm,
-				 struct bio_vec *biovec)
-{
-	struct r10conf *conf = mddev->private;
-	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
-	int max;
-	unsigned int chunk_sectors;
-	unsigned int bio_sectors = bvm->bi_size >> 9;
-	struct geom *geo = &conf->geo;
-
-	chunk_sectors = (conf->geo.chunk_mask & conf->prev.chunk_mask) + 1;
-	if (conf->reshape_progress != MaxSector &&
-	    ((sector >= conf->reshape_progress) !=
-	     conf->mddev->reshape_backwards))
-		geo = &conf->prev;
-
-	if (geo->near_copies < geo->raid_disks) {
-		max = (chunk_sectors - ((sector & (chunk_sectors - 1))
-					+ bio_sectors)) << 9;
-		if (max < 0)
-			/* bio_add cannot handle a negative return */
-			max = 0;
-		if (max <= biovec->bv_len && bio_sectors == 0)
-			return biovec->bv_len;
-	} else
-		max = biovec->bv_len;
-
-	if (mddev->merge_check_needed) {
-		struct {
-			struct r10bio r10_bio;
-			struct r10dev devs[conf->copies];
-		} on_stack;
-		struct r10bio *r10_bio = &on_stack.r10_bio;
-		int s;
-		if (conf->reshape_progress != MaxSector) {
-			/* Cannot give any guidance during reshape */
-			if (max <= biovec->bv_len && bio_sectors == 0)
-				return biovec->bv_len;
-			return 0;
-		}
-		r10_bio->sector = sector;
-		raid10_find_phys(conf, r10_bio);
-		rcu_read_lock();
-		for (s = 0; s < conf->copies; s++) {
-			int disk = r10_bio->devs[s].devnum;
-			struct md_rdev *rdev = rcu_dereference(
-				conf->mirrors[disk].rdev);
-			if (rdev && !test_bit(Faulty, &rdev->flags)) {
-				struct request_queue *q =
-					bdev_get_queue(rdev->bdev);
-				if (q->merge_bvec_fn) {
-					bvm->bi_sector = r10_bio->devs[s].addr
-						+ rdev->data_offset;
-					bvm->bi_bdev = rdev->bdev;
-					max = min(max, q->merge_bvec_fn(
-							  q, bvm, biovec));
-				}
-			}
-			rdev = rcu_dereference(conf->mirrors[disk].replacement);
-			if (rdev && !test_bit(Faulty, &rdev->flags)) {
-				struct request_queue *q =
-					bdev_get_queue(rdev->bdev);
-				if (q->merge_bvec_fn) {
-					bvm->bi_sector = r10_bio->devs[s].addr
-						+ rdev->data_offset;
-					bvm->bi_bdev = rdev->bdev;
-					max = min(max, q->merge_bvec_fn(
-							  q, bvm, biovec));
-				}
-			}
-		}
-		rcu_read_unlock();
-	}
-	return max;
-}
-
 /*
  * This routine returns the disk from which the requested read should
  * be done. There is a per-array 'next expected sequential IO' sector
@@ -821,12 +734,10 @@  retry:
 		disk = r10_bio->devs[slot].devnum;
 		rdev = rcu_dereference(conf->mirrors[disk].replacement);
 		if (rdev == NULL || test_bit(Faulty, &rdev->flags) ||
-		    test_bit(Unmerged, &rdev->flags) ||
 		    r10_bio->devs[slot].addr + sectors > rdev->recovery_offset)
 			rdev = rcu_dereference(conf->mirrors[disk].rdev);
 		if (rdev == NULL ||
-		    test_bit(Faulty, &rdev->flags) ||
-		    test_bit(Unmerged, &rdev->flags))
+		    test_bit(Faulty, &rdev->flags))
 			continue;
 		if (!test_bit(In_sync, &rdev->flags) &&
 		    r10_bio->devs[slot].addr + sectors > rdev->recovery_offset)
@@ -1326,11 +1237,9 @@  retry_write:
 			blocked_rdev = rrdev;
 			break;
 		}
-		if (rdev && (test_bit(Faulty, &rdev->flags)
-			     || test_bit(Unmerged, &rdev->flags)))
+		if (rdev && (test_bit(Faulty, &rdev->flags)))
 			rdev = NULL;
-		if (rrdev && (test_bit(Faulty, &rrdev->flags)
-			      || test_bit(Unmerged, &rrdev->flags)))
+		if (rrdev && (test_bit(Faulty, &rrdev->flags)))
 			rrdev = NULL;
 
 		r10_bio->devs[i].bio = NULL;
@@ -1777,7 +1686,6 @@  static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
 	int mirror;
 	int first = 0;
 	int last = conf->geo.raid_disks - 1;
-	struct request_queue *q = bdev_get_queue(rdev->bdev);
 
 	if (mddev->recovery_cp < MaxSector)
 		/* only hot-add to in-sync arrays, as recovery is
@@ -1790,11 +1698,6 @@  static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
 	if (rdev->raid_disk >= 0)
 		first = last = rdev->raid_disk;
 
-	if (q->merge_bvec_fn) {
-		set_bit(Unmerged, &rdev->flags);
-		mddev->merge_check_needed = 1;
-	}
-
 	if (rdev->saved_raid_disk >= first &&
 	    conf->mirrors[rdev->saved_raid_disk].rdev == NULL)
 		mirror = rdev->saved_raid_disk;
@@ -1833,19 +1736,6 @@  static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
 		rcu_assign_pointer(p->rdev, rdev);
 		break;
 	}
-	if (err == 0 && test_bit(Unmerged, &rdev->flags)) {
-		/* Some requests might not have seen this new
-		 * merge_bvec_fn.  We must wait for them to complete
-		 * before merging the device fully.
-		 * First we make sure any code which has tested
-		 * our function has submitted the request, then
-		 * we wait for all outstanding requests to complete.
-		 */
-		synchronize_sched();
-		freeze_array(conf, 0);
-		unfreeze_array(conf);
-		clear_bit(Unmerged, &rdev->flags);
-	}
 	md_integrity_add_rdev(rdev, mddev);
 	if (mddev->queue && blk_queue_discard(bdev_get_queue(rdev->bdev)))
 		queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
@@ -2404,7 +2294,6 @@  static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
 			d = r10_bio->devs[sl].devnum;
 			rdev = rcu_dereference(conf->mirrors[d].rdev);
 			if (rdev &&
-			    !test_bit(Unmerged, &rdev->flags) &&
 			    test_bit(In_sync, &rdev->flags) &&
 			    is_badblock(rdev, r10_bio->devs[sl].addr + sect, s,
 					&first_bad, &bad_sectors) == 0) {
@@ -2458,7 +2347,6 @@  static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
 			d = r10_bio->devs[sl].devnum;
 			rdev = rcu_dereference(conf->mirrors[d].rdev);
 			if (!rdev ||
-			    test_bit(Unmerged, &rdev->flags) ||
 			    !test_bit(In_sync, &rdev->flags))
 				continue;
 
@@ -3652,8 +3540,6 @@  static int run(struct mddev *mddev)
 			disk->rdev = rdev;
 		}
 		q = bdev_get_queue(rdev->bdev);
-		if (q->merge_bvec_fn)
-			mddev->merge_check_needed = 1;
 		diff = (rdev->new_data_offset - rdev->data_offset);
 		if (!mddev->reshape_backwards)
 			diff = -diff;
@@ -4706,7 +4592,6 @@  static struct md_personality raid10_personality =
 	.start_reshape	= raid10_start_reshape,
 	.finish_reshape	= raid10_finish_reshape,
 	.congested	= raid10_congested,
-	.mergeable_bvec	= raid10_mergeable_bvec,
 };
 
 static int __init raid_init(void)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index b6c6ace..18d2b23 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -4625,35 +4625,6 @@  static int raid5_congested(struct mddev *mddev, int bits)
 	return 0;
 }
 
-/* We want read requests to align with chunks where possible,
- * but write requests don't need to.
- */
-static int raid5_mergeable_bvec(struct mddev *mddev,
-				struct bvec_merge_data *bvm,
-				struct bio_vec *biovec)
-{
-	sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
-	int max;
-	unsigned int chunk_sectors = mddev->chunk_sectors;
-	unsigned int bio_sectors = bvm->bi_size >> 9;
-
-	/*
-	 * always allow writes to be mergeable, read as well if array
-	 * is degraded as we'll go through stripe cache anyway.
-	 */
-	if ((bvm->bi_rw & 1) == WRITE || mddev->degraded)
-		return biovec->bv_len;
-
-	if (mddev->new_chunk_sectors < mddev->chunk_sectors)
-		chunk_sectors = mddev->new_chunk_sectors;
-	max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
-	if (max < 0) max = 0;
-	if (max <= biovec->bv_len && bio_sectors == 0)
-		return biovec->bv_len;
-	else
-		return max;
-}
-
 static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
 {
 	sector_t sector = bio->bi_iter.bi_sector + get_start_sect(bio->bi_bdev);
@@ -7722,7 +7693,6 @@  static struct md_personality raid6_personality =
 	.quiesce	= raid5_quiesce,
 	.takeover	= raid6_takeover,
 	.congested	= raid5_congested,
-	.mergeable_bvec	= raid5_mergeable_bvec,
 };
 static struct md_personality raid5_personality =
 {
@@ -7746,7 +7716,6 @@  static struct md_personality raid5_personality =
 	.quiesce	= raid5_quiesce,
 	.takeover	= raid5_takeover,
 	.congested	= raid5_congested,
-	.mergeable_bvec	= raid5_mergeable_bvec,
 };
 
 static struct md_personality raid4_personality =
@@ -7771,7 +7740,6 @@  static struct md_personality raid4_personality =
 	.quiesce	= raid5_quiesce,
 	.takeover	= raid4_takeover,
 	.congested	= raid5_congested,
-	.mergeable_bvec	= raid5_mergeable_bvec,
 };
 
 static int __init raid5_init(void)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 93b81a2..6927b76 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -239,14 +239,6 @@  typedef int (prep_rq_fn) (struct request_queue *, struct request *);
 typedef void (unprep_rq_fn) (struct request_queue *, struct request *);
 
 struct bio_vec;
-struct bvec_merge_data {
-	struct block_device *bi_bdev;
-	sector_t bi_sector;
-	unsigned bi_size;
-	unsigned long bi_rw;
-};
-typedef int (merge_bvec_fn) (struct request_queue *, struct bvec_merge_data *,
-			     struct bio_vec *);
 typedef void (softirq_done_fn)(struct request *);
 typedef int (dma_drain_needed_fn)(struct request *);
 typedef int (lld_busy_fn) (struct request_queue *q);
@@ -331,7 +323,6 @@  struct request_queue {
 	make_request_fn		*make_request_fn;
 	prep_rq_fn		*prep_rq_fn;
 	unprep_rq_fn		*unprep_rq_fn;
-	merge_bvec_fn		*merge_bvec_fn;
 	softirq_done_fn		*softirq_done_fn;
 	rq_timed_out_fn		*rq_timed_out_fn;
 	dma_drain_needed_fn	*dma_drain_needed;
@@ -1041,7 +1032,6 @@  extern void blk_queue_lld_busy(struct request_queue *q, lld_busy_fn *fn);
 extern void blk_queue_segment_boundary(struct request_queue *, unsigned long);
 extern void blk_queue_prep_rq(struct request_queue *, prep_rq_fn *pfn);
 extern void blk_queue_unprep_rq(struct request_queue *, unprep_rq_fn *ufn);
-extern void blk_queue_merge_bvec(struct request_queue *, merge_bvec_fn *);
 extern void blk_queue_dma_alignment(struct request_queue *, int);
 extern void blk_queue_update_dma_alignment(struct request_queue *, int);
 extern void blk_queue_softirq_done(struct request_queue *, softirq_done_fn *);
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 51cc1de..76d23fa 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -82,9 +82,6 @@  typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
 typedef int (*dm_ioctl_fn) (struct dm_target *ti, unsigned int cmd,
 			    unsigned long arg);
 
-typedef int (*dm_merge_fn) (struct dm_target *ti, struct bvec_merge_data *bvm,
-			    struct bio_vec *biovec, int max_size);
-
 /*
  * These iteration functions are typically used to check (and combine)
  * properties of underlying devices.
@@ -160,7 +157,6 @@  struct target_type {
 	dm_status_fn status;
 	dm_message_fn message;
 	dm_ioctl_fn ioctl;
-	dm_merge_fn merge;
 	dm_busy_fn busy;
 	dm_iterate_devices_fn iterate_devices;
 	dm_io_hints_fn io_hints;