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authorMike Snitzer <snitzer@redhat.com>2016-01-31 17:22:27 -0500
committerMike Snitzer <snitzer@redhat.com>2016-02-22 11:06:22 -0500
commit16f122661dbb3dfefc60788b528b54ad702005aa (patch)
tree500f1868d0342e7d61eeb86337d0120532d37d78 /drivers/md/dm.h
parentf083b09b7819c785db4f82a81f68da3bccfb04bf (diff)
downloadop-kernel-dev-16f122661dbb3dfefc60788b528b54ad702005aa.zip
op-kernel-dev-16f122661dbb3dfefc60788b528b54ad702005aa.tar.gz
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.h')
-rw-r--r--drivers/md/dm.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/md/dm.h b/drivers/md/dm.h
index 53df258..4305a51 100644
--- a/drivers/md/dm.h
+++ b/drivers/md/dm.h
@@ -73,6 +73,7 @@ int dm_table_resume_targets(struct dm_table *t);
int dm_table_any_congested(struct dm_table *t, int bdi_bits);
unsigned dm_table_get_type(struct dm_table *t);
struct target_type *dm_table_get_immutable_target_type(struct dm_table *t);
+struct dm_target *dm_table_get_immutable_target(struct dm_table *t);
struct dm_target *dm_table_get_wildcard_target(struct dm_table *t);
bool dm_table_request_based(struct dm_table *t);
bool dm_table_mq_request_based(struct dm_table *t);
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