fnic: reject device resets without assigned tags for the blk-mq case

Current the midlayer fakes up a struct request for the explicit reset
ioctls, and those don't have a tag allocated to them.  The fnic driver pokes
into midlayer structures to paper over this design issue, but that won't
work for the blk-mq case.

Either someone who can actually test the hardware will have to come up with
a similar hack for the blk-mq case, or we'll have to bite the bullet and fix
the way the EH ioctls work for real, but until that happens we fail these
explicit requests here.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Webb Scales <webbnh@hp.com>
Acked-by: Jens Axboe <axboe@kernel.dk>
Tested-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Robert Elliott <elliott@hp.com>
Cc: Hiral Patel <hiralpat@cisco.com>
Cc: Suma Ramars <sramars@cisco.com>
Cc: Brian Uchino <buchino@cisco.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/drivers/scsi/fnic/fnic_scsi.c b/drivers/scsi/fnic/fnic_scsi.c
index 3f88f56582a2..961bdf5d31cd 100644
--- a/drivers/scsi/fnic/fnic_scsi.c
+++ b/drivers/scsi/fnic/fnic_scsi.c
@@ -2224,6 +2224,22 @@ int fnic_device_reset(struct scsi_cmnd *sc)
 
         tag = sc->request->tag;
         if (unlikely(tag < 0)) {
+                /*
+                 * XXX(hch): current the midlayer fakes up a struct
+                 * request for the explicit reset ioctls, and those
+                 * don't have a tag allocated to them.  The below
+                 * code pokes into midlayer structures to paper over
+                 * this design issue, but that won't work for blk-mq.
+                 *
+                 * Either someone who can actually test the hardware
+                 * will have to come up with a similar hack for the
+                 * blk-mq case, or we'll have to bite the bullet and
+                 * fix the way the EH ioctls work for real, but until
+                 * that happens we fail these explicit requests here.
+                 */
+                if (shost_use_blk_mq(sc->device->host))
+                        goto fnic_device_reset_end;
+
                 tag = fnic_scsi_host_start_tag(fnic, sc);
                 if (unlikely(tag == SCSI_NO_TAG))
                         goto fnic_device_reset_end;