From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: [PATCH] IB/srp: Fail I/O requests if the transport is offline Date: Fri, 15 Feb 2013 10:39:26 +0100 Message-ID: <511E024E.70002@acm.org> References: <510BDCAA.204@acm.org> <5111327F.6050402@acm.org> <5112049B.8030406@acm.org> <5112CE60.2030607@mellanox.com> <51136E74.9090209@acm.org> <5113F056.4020501@mellanox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5113F056.4020501-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Vu Pham Cc: Or Gerlitz , David Dillow , Roland Dreier , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Or Gerlitz , Sagi Grimberg List-Id: linux-rdma@vger.kernel.org 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) such that the SCSI error handler has a chance to retry commands after a transport layer failure occurred. Signed-off-by: Bart Van Assche Cc: David Dillow Cc: Or Gerlitz Cc: Vu Pham --- drivers/infiniband/ulp/srp/ib_srp.c | 7 +++++++ drivers/infiniband/ulp/srp/ib_srp.h | 1 + 2 files changed, 8 insertions(+) diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c index 8a7eb9f..b34752d 100644 --- a/drivers/infiniband/ulp/srp/ib_srp.c +++ b/drivers/infiniband/ulp/srp/ib_srp.c @@ -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 != 0; 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) diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h index de2d0b3..66fbedd 100644 --- a/drivers/infiniband/ulp/srp/ib_srp.h +++ b/drivers/infiniband/ulp/srp/ib_srp.h @@ -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. -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html