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authorMike Snitzer <snitzer@redhat.com>2016-02-01 01:22:27 +0300
committerMike Snitzer <snitzer@redhat.com>2016-02-22 19:06:22 +0300
commit16f122661dbb3dfefc60788b528b54ad702005aa (patch)
tree500f1868d0342e7d61eeb86337d0120532d37d78 /drivers/md/dm-table.c
parentf083b09b7819c785db4f82a81f68da3bccfb04bf (diff)
downloadlinux-16f122661dbb3dfefc60788b528b54ad702005aa.tar.xz
dm: optimize dm_mq_queue_rq()
DM multipath is the only dm-mq target. But that aside, request-based DM only supports tables with a single target that is immutable. Leverage this fact in dm_mq_queue_rq() by using the 'immutable_target' stored in the mapped_device when the table was made active. This saves the need to even take the read-side of the SRCU via dm_{get,put}_live_table. If the active DM table does not have an immutable target (e.g. "error" target was swapped in) then fallback to the slow-path where the target is looked up from the live table. Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/dm-table.c')
-rw-r--r--drivers/md/dm-table.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index a49e62b8611f..89180fdbd28c 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -920,6 +920,16 @@ struct target_type *dm_table_get_immutable_target_type(struct dm_table *t)
return t->immutable_target_type;
}
+struct dm_target *dm_table_get_immutable_target(struct dm_table *t)
+{
+ /* Immutable target is implicitly a singleton */
+ if (t->num_targets > 1 ||
+ !dm_target_is_immutable(t->targets[0].type))
+ return NULL;
+
+ return t->targets;
+}
+
struct dm_target *dm_table_get_wildcard_target(struct dm_table *t)
{
struct dm_target *uninitialized_var(ti);