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authorJames Bottomley <James.Bottomley@suse.de>2010-05-04 16:51:40 -0400
committerGreg Kroah-Hartman <gregkh@suse.de>2010-05-12 14:57:17 -0700
commit7443d2d252e4f958d080c629b593fb3836b215e5 (patch)
tree169cf299bd058a947b6672bd003e61b707e35955
parentf3dc6becaa6b5efdb5756cf6f47b724c9b32df0b (diff)
SCSI: Retry commands with UNIT_ATTENTION sense codes to fix ext3/ext4 I/O error
commit 77a4229719e511a0d38d9c355317ae1469adeb54 upstream. There's nastyness in the way we currently handle barriers (and discards): They're effectively filesystem commands, but they get processed as BLOCK_PC commands. Unfortunately BLOCK_PC commands are taken by SCSI to be SG_IO commands and the issuer expects to see and handle any returned errors, however trivial. This leads to a huge problem, because the block layer doesn't expect this to happen and any trivially retryable error on a barrier causes an immediate I/O error to the filesystem. The only real way to hack around this is to take the usual class of offending errors (unit attentions) and make them all retryable in the case of a REQ_HARDBARRIER. A correct fix would involve a rework of the entire block and SCSI submit system, and so is out of scope for a quick fix. Cc: Hannes Reinecke <hare@suse.de> Signed-off-by: James Bottomley <James.Bottomley@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--drivers/scsi/scsi_error.c15
1 files changed, 14 insertions, 1 deletions
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 1b0060b791e8..573921d00070 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -301,7 +301,20 @@ static int scsi_check_sense(struct scsi_cmnd *scmd)
if (scmd->device->allow_restart &&
(sshdr.asc == 0x04) && (sshdr.ascq == 0x02))
return FAILED;
- return SUCCESS;
+
+ if (blk_barrier_rq(scmd->request))
+ /*
+ * barrier requests should always retry on UA
+ * otherwise block will get a spurious error
+ */
+ return NEEDS_RETRY;
+ else
+ /*
+ * for normal (non barrier) commands, pass the
+ * UA upwards for a determination in the
+ * completion functions
+ */
+ return SUCCESS;
/* these three are not supported */
case COPY_ABORTED: