From: James Bottomley Date: Fri, 13 May 2016 19:04:06 +0000 (-0700) Subject: scsi_lib: correctly retry failed zero length REQ_TYPE_FS commands X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=a621bac3044ed6f7ec5fa0326491b2d4838bfa93;p=linux-beck.git scsi_lib: correctly retry failed zero length REQ_TYPE_FS commands 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: stable@vger.kernel.org Reported-by: Sebastian Parschauer Signed-off-by: James E.J. Bottomley Tested-by: Jack Wang Signed-off-by: Martin K. Petersen --- diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index b2e332af0f51..c71344aebdbb 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -821,9 +821,12 @@ 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; /*