dm mpath: return DM_MAPIO_REQUEUE on blk-mq rq allocation failure
Ming Lei authored

blk-mq will rerun queue via RESTART or dispatch wake after one request
is completed, so not necessary to wait random time for requeuing, we
should trust blk-mq to do it.

More importantly, we need to return BLK_STS_RESOURCE to blk-mq so that
dequeuing from the I/O scheduler can be stopped, this results in
improved I/O merging.
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
050af08f
Linux kernel
============

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