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| author | Mike Snitzer <snitzer@redhat.com> | 2018-01-12 19:53:40 -0500 |
|---|---|---|
| committer | Mike Snitzer <snitzer@redhat.com> | 2018-01-29 13:44:54 -0500 |
| commit | ac514ffc968bf14649dd0e048447dc966ee49555 (patch) | |
| tree | 5f855e84e686deabbe559f2b7f4e440e5c8fd2c5 /include/linux/device-mapper.h | |
| parent | 459b54019cfeb7330ed4863ad40f78489e0ff23d (diff) | |
| download | lwn-ac514ffc968bf14649dd0e048447dc966ee49555.tar.gz lwn-ac514ffc968bf14649dd0e048447dc966ee49555.zip | |
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 'include/linux/device-mapper.h')
| -rw-r--r-- | include/linux/device-mapper.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index 9ba84532947d..da83f64952e7 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -550,6 +550,7 @@ do { \ #define DM_ENDIO_DONE 0 #define DM_ENDIO_INCOMPLETE 1 #define DM_ENDIO_REQUEUE 2 +#define DM_ENDIO_DELAY_REQUEUE 3 /* * Definitions of return values from target map function. @@ -557,7 +558,7 @@ do { \ #define DM_MAPIO_SUBMITTED 0 #define DM_MAPIO_REMAPPED 1 #define DM_MAPIO_REQUEUE DM_ENDIO_REQUEUE -#define DM_MAPIO_DELAY_REQUEUE 3 +#define DM_MAPIO_DELAY_REQUEUE DM_ENDIO_DELAY_REQUEUE #define DM_MAPIO_KILL 4 #define dm_sector_div64(x, y)( \ |