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Commit 2ce19e72 authored by Bart Van Assche's avatar Bart Van Assche Committed by Roland Dreier
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IB/srp: Fail I/O requests if the transport is offline 



If an SRP target is no longer reachable and srp_reset_host() fails to
reconnect then ib_srp will invoke scsi_remove_host().  That function
will invoke __scsi_remove_device() for each LUN.  And that last
function will change the device state from SDEV_TRANSPORT_OFFLINE into
SDEV_CANCEL.  Certain user space software, e.g. older versions of
multipathd, continue queueing I/O to SCSI devices that are in the
SDEV_CANCEL state.

If these I/O requests are submitted as SG_IO that means that the
REQ_PREEMPT flag will be set and hence that these requests will be
passed to srp_queuecommand().  These requests will time out.  If new
requests are queued fast enough from user space these active requests
will prevent __scsi_remove_device() to finish.

Avoid this by failing I/O requests in the SDEV_CANCEL state if the
transport is offline.  Introduce a new variable to keep track of the
transport state instead of failing requests if (!target->connected ||
target->qp_in_error), so that the SCSI error handler has a chance to
retry commands after a transport layer failure occurred.

Signed-off-by: default avatarBart Van Assche <bvanassche@acm.org>
Cc: <stable@vger.kernel.org> # 3.8
Signed-off-by: default avatarRoland Dreier <roland@purestorage.com>
parent c7c4e7ff

drivers/infiniband/ulp/srp/ib_srp.c

+7 −0
Original line number Diff line number Diff line
@@ -734,6 +734,7 @@ static int srp_reconnect_target(struct srp_target_port *target) 


	scsi_target_unblock(&shost->shost_gendev, ret == 0 ? SDEV_RUNNING :

			    SDEV_TRANSPORT_OFFLINE);

	target->transport_offline = !!ret;



	if (ret)

		goto err;
@@ -1353,6 +1354,12 @@ static int srp_queuecommand(struct Scsi_Host *shost, struct scsi_cmnd *scmnd) 
	unsigned long flags;

	int len;



	if (unlikely(target->transport_offline)) {

		scmnd->result = DID_NO_CONNECT << 16;

		scmnd->scsi_done(scmnd);

		return 0;

	}



	spin_lock_irqsave(&target->lock, flags);

	iu = __srp_get_tx_iu(target, SRP_IU_CMD);

	if (!iu)

drivers/infiniband/ulp/srp/ib_srp.h

+1 −0
Original line number Diff line number Diff line
@@ -140,6 +140,7 @@ struct srp_target_port { 
	unsigned int		cmd_sg_cnt;

	unsigned int		indirect_size;

	bool			allow_ext_sg;

	bool			transport_offline;



	/* Everything above this point is used in the hot path of

	 * command processing. Try to keep them packed into cachelines.