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alistair23-linux/drivers/infiniband/ulp/srp
Bart Van Assche 2ce19e72f4 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: Bart Van Assche <bvanassche@acm.org>
Cc: <stable@vger.kernel.org> # 3.8
Signed-off-by: Roland Dreier <roland@purestorage.com>
2013-02-25 09:31:14 -08:00
..
Kbuild IB: Add SCSI RDMA Protocol (SRP) initiator 2005-11-02 14:07:13 -08:00
Kconfig [SCSI] ib_srp: convert to use the srp transport class 2007-10-12 14:37:42 -04:00
ib_srp.c IB/srp: Fail I/O requests if the transport is offline 2013-02-25 09:31:14 -08:00
ib_srp.h IB/srp: Fail I/O requests if the transport is offline 2013-02-25 09:31:14 -08:00