From 23508a96cd2e857d57044a2ed7d305f2d9daf441 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Fri, 21 Dec 2012 20:23:37 +0000 Subject: [PATCH] dm: add WRITE SAME support WRITE SAME bios have a payload that contain a single page. When cloning WRITE SAME bios DM has no need to modify the bi_io_vec attributes (and doing so would be detrimental). DM need only alter the start and end of the WRITE SAME bio accordingly. Rather than duplicate __clone_and_map_discard, factor out a common function that is also used by __clone_and_map_write_same. Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon --- drivers/md/dm.c | 44 +++++++++++++++++++++++++++++++++++++++----- 1 file changed, 39 insertions(+), 5 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 77e6eff..5401cdc 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1174,7 +1174,28 @@ static void __clone_and_map_simple(struct clone_info *ci, struct dm_target *ti) ci->sector_count = 0; } -static int __clone_and_map_discard(struct clone_info *ci) +typedef unsigned (*get_num_requests_fn)(struct dm_target *ti); + +static unsigned get_num_discard_requests(struct dm_target *ti) +{ + return ti->num_discard_requests; +} + +static unsigned get_num_write_same_requests(struct dm_target *ti) +{ + return ti->num_write_same_requests; +} + +typedef bool (*is_split_required_fn)(struct dm_target *ti); + +static bool is_split_required_for_discard(struct dm_target *ti) +{ + return ti->split_discard_requests; +} + +static int __clone_and_map_changing_extent_only(struct clone_info *ci, + get_num_requests_fn get_num_requests, + is_split_required_fn is_split_required) { struct dm_target *ti; sector_t len; @@ -1185,15 +1206,15 @@ static int __clone_and_map_discard(struct clone_info *ci) return -EIO; /* - * Even though the device advertised discard support, - * that does not mean every target supports it, and + * Even though the device advertised support for this type of + * request, that does not mean every target supports it, and * reconfiguration might also have changed that since the * check was performed. */ - if (!ti->num_discard_requests) + if (!get_num_requests || !get_num_requests(ti)) return -EOPNOTSUPP; - if (!ti->split_discard_requests) + if (is_split_required && !is_split_required(ti)) len = min(ci->sector_count, max_io_len_target_boundary(ci->sector, ti)); else len = min(ci->sector_count, max_io_len(ci->sector, ti)); @@ -1206,6 +1227,17 @@ static int __clone_and_map_discard(struct clone_info *ci) return 0; } +static int __clone_and_map_discard(struct clone_info *ci) +{ + return __clone_and_map_changing_extent_only(ci, get_num_discard_requests, + is_split_required_for_discard); +} + +static int __clone_and_map_write_same(struct clone_info *ci) +{ + return __clone_and_map_changing_extent_only(ci, get_num_write_same_requests, NULL); +} + static int __clone_and_map(struct clone_info *ci) { struct bio *bio = ci->bio; @@ -1215,6 +1247,8 @@ static int __clone_and_map(struct clone_info *ci) if (unlikely(bio->bi_rw & REQ_DISCARD)) return __clone_and_map_discard(ci); + else if (unlikely(bio->bi_rw & REQ_WRITE_SAME)) + return __clone_and_map_write_same(ci); ti = dm_table_find_target(ci->map, ci->sector); if (!dm_target_is_valid(ti)) -- 2.7.4