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authorJames Bottomley <James.Bottomley@HansenPartnership.com>2016-05-13 12:04:06 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-06-24 10:18:16 -0700
commit0dec8c0d67c64401d97122e4eba347ccc5850622 (patch)
tree097a50947e94e9dc78759be648d6eb4edfd3380a
parentba760d4302e4fce130007b8bdbce7fcafc9bd9a9 (diff)
downloadlinux-linaro-stable-0dec8c0d67c64401d97122e4eba347ccc5850622.tar.gz
scsi_lib: correctly retry failed zero length REQ_TYPE_FS commands
commit a621bac3044ed6f7ec5fa0326491b2d4838bfa93 upstream. When SCSI was written, all commands coming from the filesystem (REQ_TYPE_FS commands) had data. This meant that our signal for needing to complete the command was the number of bytes completed being equal to the number of bytes in the request. Unfortunately, with the advent of flush barriers, we can now get zero length REQ_TYPE_FS commands, which confuse this logic because they satisfy the condition every time. This means they never get retried even for retryable conditions, like UNIT ATTENTION because we complete them early assuming they're done. Fix this by special casing the early completion condition to recognise zero length commands with errors and let them drop through to the retry code. Reported-by: Sebastian Parschauer <s.parschauer@gmx.de> Signed-off-by: James E.J. Bottomley <jejb@linux.vnet.ibm.com> Tested-by: Jack Wang <jinpu.wang@profitbricks.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/scsi/scsi_lib.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index dd8ad2a44510..cf5b99e1f12b 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -910,9 +910,12 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
}
/*
- * If we finished all bytes in the request we are done now.
+ * special case: failed zero length commands always need to
+ * drop down into the retry code. Otherwise, if we finished
+ * all bytes in the request we are done now.
*/
- if (!scsi_end_request(req, error, good_bytes, 0))
+ if (!(blk_rq_bytes(req) == 0 && error) &&
+ !scsi_end_request(req, error, good_bytes, 0))
return;
/*