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Commit 36f12aeb authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm thin: implement thin_merge 



Introduce thin_merge so that any additional constraints from the data
volume may be taken into account when determing the maximum number of
sectors that can be issued relative to the specified logical offset.

This is particularly important if/when the data volume is layered ontop
of a more sophisticated device (e.g. dm-raid or some other DM target).

Reviewed-by: default avatarHeinz Mauelshagen <heinzm@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 148e51ba

drivers/md/dm-thin.c

+18 −2
Original line number Diff line number Diff line
@@ -3307,7 +3307,7 @@ static struct target_type pool_target = { 
	.name = "thin-pool",

	.features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE |

		    DM_TARGET_IMMUTABLE,

	.version = {1, 13, 0},

	.version = {1, 14, 0},

	.module = THIS_MODULE,

	.ctr = pool_ctr,

	.dtr = pool_dtr,
@@ -3634,6 +3634,21 @@ static void thin_status(struct dm_target *ti, status_type_t type, 
	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)

{
@@ -3658,7 +3673,7 @@ static int thin_iterate_devices(struct dm_target *ti, 


static struct target_type thin_target = {

	.name = "thin",

	.version = {1, 13, 0},

	.version = {1, 14, 0},

	.module	= THIS_MODULE,

	.ctr = thin_ctr,

	.dtr = thin_dtr,
@@ -3668,6 +3683,7 @@ static struct target_type thin_target = { 
	.presuspend = thin_presuspend,

	.postsuspend = thin_postsuspend,

	.status = thin_status,

	.merge = thin_merge,

	.iterate_devices = thin_iterate_devices,

};