From 36f12aeb714fc04752997d6c07b6afb2fa0ac947 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Thu, 9 Oct 2014 15:24:12 -0400 Subject: [PATCH] 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: Heinz Mauelshagen Signed-off-by: Mike Snitzer --- drivers/md/dm-thin.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index de55ae9d4926..068607828691 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -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 @@ 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) { @@ -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, };