Add a use_cmd_list flag in struct Scsi_Host to request keeping track of
all outstanding commands per device.
Default behaviour is not to keep track of cmd_list per sdev, as this may
introduce lock contention. (overhead is more on multi-node NUMA.), and
only enable it on the two drivers that need it.
Signed-off-by: Kashyap Desai <kashyap.desai@avagotech.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
A bit of churn on the for-linus side that would be nice to have
in the core bits for 3.18, so pull it in to catch us up and make
forward progress easier.
Signed-off-by: Jens Axboe <axboe@fb.com>
Conflicts:
block/scsi_ioctl.c
Pull block layer fixes from Jens Axboe:
"A smaller collection of fixes that have come up since the initial
merge window pull request. This contains:
- error handling cleanup and support for larger than 16 byte cdbs in
sg_io() from Christoph. The latter just matches what bsg and
friends support, sg_io() got left out in the merge.
- an option for brd to expose partitions in /proc/partitions. They
are hidden by default for compat reasons. From Dmitry Monakhov.
- a few blk-mq fixes from me - killing a dead/unused flag, fix for
merging happening even if turned off, and correction of a few
comments.
- removal of unnecessary ->owner setting in systemace. From Michal
Simek.
- two related fixes for a problem with nesting freezing of queues in
blk-mq. One from Ming Lei removing an unecessary freeze operation,
and another from Tejun fixing the nesting regression introduced in
the merge window.
- fix for a BUG_ON() at bio_endio time when protection info is
attached and the IO has an error. From Sagi Grimberg.
- two scsi_ioctl bug fixes for regressions with scsi-mq from Tony
Battersby.
- a cfq weight update fix and subsequent comment update from Toshiaki
Makita"
* 'for-linus' of git://git.kernel.dk/linux-block:
cfq-iosched: Add comments on update timing of weight
cfq-iosched: Fix wrong children_weight calculation
block: fix error handling in sg_io
fix regression in SCSI_IOCTL_SEND_COMMAND
scsi-mq: fix requests that use a separate CDB buffer
block: support > 16 byte CDBs for SG_IO
block: cleanup error handling in sg_io
brd: add ram disk visibility option
block: systemace: Remove .owner field for driver
blk-mq: blk_mq_freeze_queue() should allow nesting
blk-mq: correct a few wrong/bad comments
block: Fix BUG_ON when pi errors occur
blk-mq: don't allow merges if turned off for the queue
blk-mq: get rid of unused BLK_MQ_F_SHOULD_SORT flag
blk-mq: fix WARNING "percpu_ref_kill() called more than once!"
The blk_get_request function may fail in low-memory conditions or during
device removal (even if __GFP_WAIT is set). To distinguish between these
errors, modify the blk_get_request call stack to return the appropriate
ERR_PTR. Verify that all callers check the return status and consider
IS_ERR instead of a simple NULL pointer check.
For consistency, make a similar change to the blk_mq_alloc_request leg
of blk_get_request. It may fail if the queue is dead, or the caller was
unwilling to wait.
Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com>
Acked-by: Jiri Kosina <jkosina@suse.cz> [for pktdvd]
Acked-by: Boaz Harrosh <bharrosh@panasas.com> [for osd]
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This patch fixes code such as the following with scsi-mq enabled:
rq = blk_get_request(...);
blk_rq_set_block_pc(rq);
rq->cmd = my_cmd_buffer; /* separate CDB buffer */
blk_execute_rq_nowait(...);
Code like this appears in e.g. sg_start_req() in drivers/scsi/sg.c (for
large CDBs only). Without this patch, scsi_mq_prep_fn() will set
rq->cmd back to rq->__cmd, causing the wrong CDB to be sent to the device.
Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
The latest kernel fails to boot qemu arm images when using scsi
for disk access. Boot gets stuck after the following messages.
brd: module loaded
sym53c8xx 0000:00:0c.0: enabling device (0100 -> 0103)
sym0: <895a> rev 0x0 at pci 0000:00:0c.0 irq 93
sym0: No NVRAM, ID 7, Fast-40, LVD, parity checking
sym0: SCSI BUS has been reset.
scsi host0: sym-2.2.3
Bisect points to commit 71e75c97f9 ("scsi: convert device_busy to
atomic_t"). Code inspection shows the following suspicious change
in scsi_request_fn.
out_delay:
- if (sdev->device_busy == 0 && !scsi_device_blocked(sdev))
+ if (atomic_read(&sdev->device_busy) && !scsi_device_blocked(sdev))
blk_delay_queue(q, SCSI_QUEUE_DELAY);
}
'sdev->device_busy == 0' was replaced with 'atomic_read(&sdev->device_busy)',
meaning the logic was reversed. Changing this expression to
'!atomic_read(&sdev->device_busy)' fixes the problem.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Venkatesh Srinivas <venkateshs@google.com>
Reviewed-by: Webb Scales <webbnh@hp.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch adds support for an alternate I/O path in the scsi midlayer
which uses the blk-mq infrastructure instead of the legacy request code.
Use of blk-mq is fully transparent to drivers, although for now a host
template field is provided to opt out of blk-mq usage in case any unforseen
incompatibilities arise.
In general replacing the legacy request code with blk-mq is a simple and
mostly mechanical transformation. The biggest exception is the new code
that deals with the fact the I/O submissions in blk-mq must happen from
process context, which slightly complicates the I/O completion handler.
The second biggest differences is that blk-mq is build around the concept
of preallocated requests that also include driver specific data, which
in SCSI context means the scsi_cmnd structure. This completely avoids
dynamic memory allocations for the fast path through I/O submission.
Due the preallocated requests the MQ code path exclusively uses the
host-wide shared tag allocator instead of a per-LUN one. This only
affects drivers actually using the block layer provided tag allocator
instead of their own. Unlike the old path blk-mq always provides a tag,
although drivers don't have to use it.
For now the blk-mq path is disable by defauly and must be enabled using
the "use_blk_mq" module parameter. Once the remaining work in the block
layer to make blk-mq more suitable for slow devices is complete I hope
to make it the default and eventually even remove the old code path.
Based on the earlier scsi-mq prototype by Nicholas Bellinger.
Thanks to Bart Van Assche and Robert Elliot for testing, benchmarking and
various sugestions and code contributions.
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>
Blk-mq drivers usually preallocate their S/G list as part of the request,
but if we want to support the very large S/G lists currently supported by
the SCSI code that would tie up a lot of memory in the preallocated request
pool. Add support to the scatterlist code so that it can initialize a
S/G list that uses a preallocated first chunks and dynamically allocated
additional chunks. That way the scsi-mq code can preallocate a first
page worth of S/G entries as part of the request, and dynamically extend
the S/G list when needed.
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>
Replace the calls to the various blk_end_request variants with opencode
equivalents. Blk-mq is using a model that gives the driver control
between the bio updates and the actual completion, and making the old
code follow that same model allows us to keep the code more similar for
both paths.
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>
This saves us an atomic operation for each I/O submission and completion
for the usual case where the driver doesn't set a per-target can_queue
value. Only a few iscsi hardware offload drivers set the per-target
can_queue value at the moment.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
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>
Seems like these counters are missing any sort of synchronization for
updates, as a over 10 year old comment from me noted. Fix this by
using atomic counters, and while we're at it also make sure they are
in the same cacheline as the _busy counters and not needlessly stored
to in every I/O completion.
With the new model the _busy counters can temporarily go negative,
so all the readers are updated to check for > 0 values. Longer
term every successful I/O completion will reset the counters to zero,
so the temporarily negative values will not cause any harm.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
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>
Avoid taking the queue_lock to check the per-device queue limit. Instead
we do an atomic_inc_return early on to grab our slot in the queue,
and if necessary decrement it after finishing all checks.
Unlike the host and target busy counters this doesn't allow us to avoid the
queue_lock in the request_fn due to the way the interface works, but it'll
allow us to prepare for using the blk-mq code, which doesn't use the
queue_lock at all, and it at least avoids a queue_lock round trip in
scsi_device_unbusy, which is still important given how busy the queue_lock
is.
Signed-off-by: Christoph Hellwig <hch@lst.de>
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>
Avoid taking the host-wide host_lock to check the per-host queue limit.
Instead we do an atomic_inc_return early on to grab our slot in the queue,
and if necessary decrement it after finishing all checks.
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>
Avoid taking the host-wide host_lock to check the per-target queue limit.
Instead we do an atomic_inc_return early on to grab our slot in the queue,
and if necessary decrement it after finishing all checks.
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>
Prepare for not taking a host-wide lock in the dispatch path by pushing
the lock down into the places that actually need it. Note that this
patch is just a preparation step, as it will actually increase lock
roundtrips and thus decrease performance on its own.
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>
The blk-mq code path will set this to a different function, so make the
code simpler by setting it up in a legacy-request specific place.
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>
Factor out command setup code that will be shared with the blk-mq code path.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Webb Scales <webbnh@hp.com>
The data direction fiel in the SCSI command is derived only from the block
request structure. Move setting it up into common code instead of
duplicating it in the ULDs.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
We should call the device handler prep_fn for all TYPE_FS requests,
not just simple read/write calls that are handled by the disk driver.
Restructure the common I/O code to call the prep_fn handler and zero
out the CDB, and just leave the call to scsi_init_io to the ULDs.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
scsi_init_io should only be called for requests that transfer data,
so move the assert that a request has segments from the callers into
scsi_init_io.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
During IO with fabric faults, one generally sees several "Unhandled error
code" messages in the syslog as shown below:
sd 4:0:6:2: [sdbw] Unhandled error code
sd 4:0:6:2: [sdbw] Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK
sd 4:0:6:2: [sdbw] CDB: Read(10): 28 00 00 00 00 00 00 00 08 00
end_request: I/O error, dev sdbw, sector 0
This comes from scsi_io_completion (in scsi_lib.c) while handling error
codes other than DID_RESET or not deferred sense keys i.e. this is
actually handled by the SCSI mid layer. But what gets displayed here is
"Unhandled error code" which is quite misleading as it indicates
something that is not addressed by the mid layer.
The description string is based on the sense key and sometimes on the
additional sense code;
since the ACTION_FAIL case always prints the sense key and the
additional sense code, this patch removes the description string
completely because it does not add useful information.
Signed-off-by: Maurizio Lombardi <mlombard@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Kashyap.Desai@avagotech.com
Jens Axboe
Linus Torvalds
Joe Lawrence
Tony Battersby
Guenter Roeck
Christoph Hellwig
Maurizio Lombardi