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authorMike Snitzer <snitzer@redhat.com>2018-01-12 19:53:40 -0500
committerMike Snitzer <snitzer@redhat.com>2018-01-29 13:44:54 -0500
commitac514ffc968bf14649dd0e048447dc966ee49555 (patch)
tree5f855e84e686deabbe559f2b7f4e440e5c8fd2c5 /drivers/md
parent459b54019cfeb7330ed4863ad40f78489e0ff23d (diff)
dm mpath: delay the retry of a request if the target responded as busy
Add DM_ENDIO_DELAY_REQUEUE to allow request-based multipath's multipath_end_io() to instruct dm-rq.c:dm_done() to delay a requeue. This is beneficial to do if BLK_STS_RESOURCE is returned from the target (because target is busy). Relative to blk-mq: kick the hw queues via blk_mq_requeue_work(), indirectly from dm-rq.c:__dm_mq_kick_requeue_list(), after a delay. For old .request_fn: use blk_delay_queue(). bio-based multipath doesn't have feature parity with request-based for retryable error requeues; that is something that'll need fixing in the future. Suggested-by: Bart Van Assche <bart.vanassche@wdc.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Acked-by: Bart Van Assche <bart.vanassche@wdc.com> [as interpreted from Bart's "... patch looks fine to me."]
Diffstat (limited to 'drivers/md')
-rw-r--r--drivers/md/dm-mpath.c5
-rw-r--r--drivers/md/dm-rq.c4
2 files changed, 8 insertions, 1 deletions
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 815de2b091a5..a8b1ffc0cb3d 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1585,7 +1585,10 @@ static int multipath_end_io(struct dm_target *ti, struct request *clone,
if (error && !noretry_error(error)) {
struct multipath *m = ti->private;
- r = DM_ENDIO_REQUEUE;
+ if (error == BLK_STS_RESOURCE)
+ r = DM_ENDIO_DELAY_REQUEUE;
+ else
+ r = DM_ENDIO_REQUEUE;
if (pgpath)
fail_path(pgpath);
diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
index 9d32f25489c2..b78ff6921cfb 100644
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -315,6 +315,10 @@ static void dm_done(struct request *clone, blk_status_t error, bool mapped)
/* The target wants to requeue the I/O */
dm_requeue_original_request(tio, false);
break;
+ case DM_ENDIO_DELAY_REQUEUE:
+ /* The target wants to requeue the I/O after a delay */
+ dm_requeue_original_request(tio, true);
+ break;
default:
DMWARN("unimplemented target endio return value: %d", r);
BUG();