LU-12946 kernel: fix to handle BLK_MQ_RQ_QUEUE_DEV_BUSY event

It looks like what's happening is when dm_dispatch_clone_request
dispatches the "clone" I/O request to the underlying (real) device
from the multipath device, the scsi driver can (often under load)
return BLK_MQ_RQ_QUEUE_DEV_BUSY. dm_dispatch_clone_request doesn't
have that as an exception the way it does BLK_MQ_RQ_QUEUE_BUSY and
so it calls dm_complete_request which propagates
the BLK_MQ_RQ_QUEUE_DEV_BUSY error code up the stack resulting
in multipath_end_io calling fail_path and failing the path because
there is an error value set.

Signed-off-by: Wang Shilong <wshilong@ddn.com>
Change-Id: If17ea5b3ab33a89a17d49e5dfb2e9f9f19371564
Reviewed-on: https://review.whamcloud.com/36699
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Yang Sheng <ys@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Li Dongyang <dongyangli@ddn.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/lustre/kernel_patches/patches/dm-fix-handle-BLK_MQ_RQ_QUEUE_DEV_BUSY-rhel7.6.patch b/lustre/kernel_patches/patches/dm-fix-handle-BLK_MQ_RQ_QUEUE_DEV_BUSY-rhel7.6.patch
new file mode 100644 (file)
index 0000000..b6b4e61
--- /dev/null
+++ b/lustre/kernel_patches/patches/dm-fix-handle-BLK_MQ_RQ_QUEUE_DEV_BUSY-rhel7.6.patch
@@ -0,0 +1,33 @@
+It looks like what's happening is when dm_dispatch_clone_request
+dispatches the "clone" I/O request to the underlying (real) device
+from the multipath device, the scsi driver can (often under load)
+return BLK_MQ_RQ_QUEUE_DEV_BUSY. dm_dispatch_clone_request doesn't
+have that as an exception the way it does BLK_MQ_RQ_QUEUE_BUSY and
+so it calls dm_complete_request which propagates
+the BLK_MQ_RQ_QUEUE_DEV_BUSY error code up the stack resulting
+in multipath_end_io calling fail_path and failing the path because
+there is an error value set.
+
+diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
+index 02da1e65..e4f58472 100644
+--- a/drivers/md/dm-rq.c
++++ b/drivers/md/dm-rq.c
+@@ -477,7 +477,8 @@ static int dm_dispatch_clone_request(struct request *clone, struct request *rq)
+ 
+       clone->start_time = jiffies;
+       r = blk_insert_cloned_request(clone->q, clone);
+-      if (r != BLK_MQ_RQ_QUEUE_OK && r != BLK_MQ_RQ_QUEUE_BUSY)
++      if (r != BLK_MQ_RQ_QUEUE_OK && r != BLK_MQ_RQ_QUEUE_BUSY &&
++          r != BLK_MQ_RQ_QUEUE_DEV_BUSY)
+               /* must complete clone in terms of original request */
+               dm_complete_request(rq, r);
+       return r;
+@@ -661,7 +662,7 @@ check_again:
+               trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)),
+                                    blk_rq_pos(rq));
+               ret = dm_dispatch_clone_request(clone, rq);
+-              if (ret == BLK_MQ_RQ_QUEUE_BUSY) {
++              if (ret == BLK_MQ_RQ_QUEUE_BUSY || ret == BLK_MQ_RQ_QUEUE_DEV_BUSY) {
+                       blk_rq_unprep_clone(clone);
+                       tio->ti->type->release_clone_rq(clone);
+                       tio->clone = NULL;

diff --git a/lustre/kernel_patches/series/3.10-rhel7.6.series b/lustre/kernel_patches/series/3.10-rhel7.6.series
index a368aad..92b320b 100644 (file)
--- a/lustre/kernel_patches/series/3.10-rhel7.6.series
+++ b/lustre/kernel_patches/series/3.10-rhel7.6.series
@@ -6,3 +6,4 @@ fix-integrity-verify-rhel7.patch
 fix-sd-dif-complete-rhel7.patch
 block-integrity-allow-optional-integrity-functions-rhel7.patch
 block-pass-bio-into-integrity_processing_fn-rhel7.patch
+dm-fix-handle-BLK_MQ_RQ_QUEUE_DEV_BUSY-rhel7.6.patch

diff --git a/lustre/kernel_patches/series/3.10-rhel7.7.series b/lustre/kernel_patches/series/3.10-rhel7.7.series
index a368aad..92b320b 100644 (file)
--- a/lustre/kernel_patches/series/3.10-rhel7.7.series
+++ b/lustre/kernel_patches/series/3.10-rhel7.7.series
@@ -6,3 +6,4 @@ fix-integrity-verify-rhel7.patch
 fix-sd-dif-complete-rhel7.patch
 block-integrity-allow-optional-integrity-functions-rhel7.patch
 block-pass-bio-into-integrity_processing_fn-rhel7.patch
+dm-fix-handle-BLK_MQ_RQ_QUEUE_DEV_BUSY-rhel7.6.patch