|author||James Bottomley <James.Bottomley@HansenPartnership.com>||2016-05-13 12:04:06 -0700|
|committer||Sasha Levin <firstname.lastname@example.org>||2016-06-18 16:52:45 -0400|
scsi_lib: correctly retry failed zero length REQ_TYPE_FS commands
[ Upstream commit a621bac3044ed6f7ec5fa0326491b2d4838bfa93 ] 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. Cc: email@example.com Reported-by: Sebastian Parschauer <firstname.lastname@example.org> Signed-off-by: James E.J. Bottomley <email@example.com> Tested-by: Jack Wang <firstname.lastname@example.org> Signed-off-by: Martin K. Petersen <email@example.com> Signed-off-by: Sasha Levin <firstname.lastname@example.org>
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index b1ab509d0e05..a11837054d6c 100644
@@ -919,9 +919,12 @@ 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))