From: Christoph Hellwig <hch@lst.de>
Date: Thu, 12 Jun 2014 12:53:23 +0000 (+0200)
Subject: fnic: reject device resets without assigned tags for the blk-mq case
X-Git-Tag: v3.17-rc1~100^2~80
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=4d63716898b5390900a802d889b279ade85f3dac;p=linux.git

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>
---

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;