scsi,block: update SCSI to handle mixed merge failures

Update scsi_io_completion() such that it only fails requests till the
next error boundary and retry the leftover.  This enables block layer
to merge requests with different failfast settings and still behave
correctly on errors.  Allow merge of requests of different failfast
settings.

As SCSI is currently the only subsystem which follows failfast status,
there's no need to worry about other block drivers for now.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Niel Lambrechts <niel.lambrechts@gmail.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index f3c40898fc7d..90c94da8baa4 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -897,8 +897,10 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
                         if (driver_byte(result) & DRIVER_SENSE)
                                 scsi_print_sense("", cmd);
                 }
-                blk_end_request_all(req, -EIO);
-                scsi_next_command(cmd);
+                if (blk_end_request_err(req, -EIO))
+                        scsi_requeue_command(q, cmd);
+                else
+                        scsi_next_command(cmd);
                 break;
         case ACTION_REPREP:
                 /* Unprep the request and put it back at the head of the queue.