This is a note to let you know that I've just added the patch titled scsi_lib: correctly retry failed zero length REQ_TYPE_FS commands to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: scsi_lib-correctly-retry-failed-zero-length-req_type_fs-commands.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From a621bac3044ed6f7ec5fa0326491b2d4838bfa93 Mon Sep 17 00:00:00 2001 From: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> Date: Fri, 13 May 2016 12:04:06 -0700 Subject: scsi_lib: correctly retry failed zero length REQ_TYPE_FS commands From: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> 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@xxxxxx> Signed-off-by: James E.J. Bottomley <jejb@xxxxxxxxxxxxxxxxxx> Tested-by: Jack Wang <jinpu.wang@xxxxxxxxxxxxxxxx> Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/scsi/scsi_lib.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -910,9 +910,12 @@ void scsi_io_completion(struct scsi_cmnd } /* - * 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; /* Patches currently in stable-queue which might be from James.Bottomley@xxxxxxxxxxxxxxxxxxxxx are queue-4.4/scsi_lib-correctly-retry-failed-zero-length-req_type_fs-commands.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html