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2015-06-05NVMe: Automatic namespace rescanKeith Busch
Namespaces may be dynamically allocated and deleted or attached and detached. This has the driver rescan the device for namespace changes after each device reset or namespace change asynchronous event. There could potentially be many detached namespaces that we don't want polluting /dev/ with unusable block handles, so this will delete disks if the namespace is not active as indicated by the response from identify namespace. This also skips adding the disk if no capacity is provisioned to the namespace in the first place. Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-05Merge branch 'for-4.2/core' into for-4.2/driversJens Axboe
2015-06-05block: add blk_set_queue_dying() to blkdev.hJens Axboe
We export this function and NVMe wants to use it, but for some reason it was never added to the block header. Do that. Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-05NVMe: Memory barrier before queue_count is incrementedJon Derrick
Protects against reordering and/or preempting which would allow the kthread to access the queue descriptor before it is set up Signed-off-by: Jon Derrick <jonathan.derrick@intel.com> Acked-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-05NVMe: add sysfs and ioctl controller resetKeith Busch
We need the ability to perform an nvme controller reset as discussed on the mailing list thread: http://lists.infradead.org/pipermail/linux-nvme/2015-March/001585.html This adds a sysfs entry that when written to will reset perform an NVMe controller reset if the controller was successfully initialized in the first place. This also adds locking around resetting the device in the async probe method so the driver can't schedule two resets. Signed-off-by: Keith Busch <keith.busch@intel.com> Cc: Brandon Schultz <brandon.schulz@hgst.com> Cc: David Sariel <david.sariel@pmcs.com> Updated by Jens to: 1) Merge this with the ioctl reset patch from David Sariel. The ioctl path now shares the reset code from the sysfs path. 2) Don't flush work if we fail issuing the reset. Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-01null_blk: restart request processing on completion handlerAkinobu Mita
When irqmode=2 (IRQ completion handler is timer) and queue_mode=1 (Block interface to use is rq), the completion handler should restart request handling for any pending requests on a queue because request processing stops when the number of commands are queued more than hw_queue_depth (null_rq_prep_fn returns BLKPREP_DEFER). Without this change, the following command cannot finish. # modprobe null_blk irqmode=2 queue_mode=1 hw_queue_depth=1 # fio --name=t --rw=read --size=1g --direct=1 \ --ioengine=libaio --iodepth=64 --filename=/dev/nullb0 Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Jens Axboe <axboe@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-01null_blk: prevent timer handler running on a different CPU where startedAkinobu Mita
When irqmode=2 (IRQ completion handler is timer), timer handler should be called on the same CPU where the timer has been started. Since completion_queues are per-cpu and the completion handler only touches completion_queue for local CPU, we need to prevent the handler from running on a different CPU where the timer has been started. Otherwise, the IO cannot be completed until another completion handler is executed on that CPU. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Jens Axboe <axboe@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-01NVMe: Remove hctx reliance for multi-namespaceKeith Busch
The driver needs to track shared tags to support multiple namespaces that may be dynamically allocated or deleted. Relying on the first request_queue's hctx's is not appropriate as we cannot clear outstanding tags for all namespaces using this handle, nor can the driver easily track all request_queue's hctx as namespaces are attached/detached. Instead, this patch uses the nvme_dev's tagset to get the shared tag resources instead of through a request_queue hctx. Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-01Merge branch 'for-4.2/core' into for-4.2/driversJens Axboe
2015-06-01blk-mq: Shared tag enhancementsKeith Busch
Storage controllers may expose multiple block devices that share hardware resources managed by blk-mq. This patch enhances the shared tags so a low-level driver can access the shared resources not tied to the unshared h/w contexts. This way the LLD can dynamically add and delete disks and request queues without having to track all the request_queue hctx's to iterate outstanding tags. Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-29block: don't honor chunk sizes for data-less IOJens Axboe
We don't need to honor chunk sizes for IO that doesn't carry any data. Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-29block: only honor SG gap prevention for merges that contain dataJens Axboe
We can safely merge anything that wont generate an SG list entry, so if the bio is data-less (discard), don't look at potential SG gaps. Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-29NVMe: End sync requests immediately on failureKeith Busch
Do not retry failed sync commands so the original status may be seen without issuing unnecessary retries. Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-29NVMe: Use requested sync command timeoutKeith Busch
Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-26block: fix returnvar.cocci warningsJulia Lawall
Remove unneeded variable used to store return value. Generated by: scripts/coccinelle/misc/returnvar.cocci Signed-off-by: Fengguang Wu <fengguang.wu@intel.com> Signed-off-by: Julia Lawall <julia.lawall@lip6.fr> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22NVMe: Fix obtaining command resultKeith Busch
Replaces req->sense_len usage, which is not owned by the LLD, to req->special to contain the command result for driver created commands, and sets the result unconditionally on completion. Signed-off-by: Keith Busch <keith.busch@intel.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Jens Axboe <axboe@fb.com> Fixes: d29ec8241c10 ("nvme: submit internal commands through the block layer") Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22block, dm: don't copy bios for request clonesChristoph Hellwig
Currently dm-multipath has to clone the bios for every request sent to the lower devices, which wastes cpu cycles and ties down memory. This patch instead adds a new REQ_CLONE flag that instructs req_bio_endio to not complete bios attached to a request, which we set on clone requests similar to bios in a flush sequence. With this change I/O errors on a path failure only get propagated to dm-multipath, which can then either resubmit the I/O or complete the bios on the original request. I've done some basic testing of this on a Linux target with ALUA support, and it survives path failures during I/O nicely. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22block: remove management of bi_remaining when restoring original bi_end_ioMike Snitzer
Commit c4cf5261 ("bio: skip atomic inc/dec of ->bi_remaining for non-chains") regressed all existing callers that followed this pattern: 1) saving a bio's original bi_end_io 2) wiring up an intermediate bi_end_io 3) restoring the original bi_end_io from intermediate bi_end_io 4) calling bio_endio() to execute the restored original bi_end_io The regression was due to BIO_CHAIN only ever getting set if bio_inc_remaining() is called. For the above pattern it isn't set until step 3 above (step 2 would've needed to establish BIO_CHAIN). As such the first bio_endio(), in step 2 above, never decremented __bi_remaining before calling the intermediate bi_end_io -- leaving __bi_remaining with the value 1 instead of 0. When bio_inc_remaining() occurred during step 3 it brought it to a value of 2. When the second bio_endio() was called, in step 4 above, it should've called the original bi_end_io but it didn't because there was an extra reference that wasn't dropped (due to atomic operations being optimized away since BIO_CHAIN wasn't set upfront). Fix this issue by removing the __bi_remaining management complexity for all callers that use the above pattern -- bio_chain() is the only interface that _needs_ to be concerned with __bi_remaining. For the above pattern callers just expect the bi_end_io they set to get called! Remove bio_endio_nodec() and also remove all bio_inc_remaining() calls that aren't associated with the bio_chain() interface. Also, the bio_inc_remaining() interface has been moved local to bio.c. Fixes: c4cf5261 ("bio: skip atomic inc/dec of ->bi_remaining for non-chains") Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22nvme: submit internal commands through the block layerChristoph Hellwig
Use block layer queues with an internal cmd_type to submit internally generated NVMe commands. This both simplifies the code a lot and allow for a better structure. For example now the LighNVM code can construct commands without knowing the details of the underlying I/O descriptors. Or a future NVMe over network target could inject commands, as well as could the SCSI translation and ioctl code be reused for such a beast. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22nvme: fail SCSI read/write command with unsupported protection bitChristoph Hellwig
Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22nvme: report the DPOFUA in MODE_SENSEChristoph Hellwig
NVMe device always support the FUA bit, and the SCSI translations accepts the DPO bit, which doesn't have much of a meaning for us. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22nvme: simplify and cleanup the READ/WRITE SCSI CDB parsing codeChristoph Hellwig
Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22nvme: first round at deobsfucating the SCSI translation codeChristoph Hellwig
Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22nvme: fix scsi translation error handlingChristoph Hellwig
Erorr handling for the scsi translation was completely broken, as there were two different positive error number spaces overlapping. Fix this up by removing one of them, and centralizing the generation of the other positive values in a single place. Also fix up a few places that didn't handle the NVMe error codes properly. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22nvme: split nvme_trans_send_fw_cmdChristoph Hellwig
This function handles two totally different opcodes, so split it. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22nvme: store a struct device pointer in struct nvme_devChristoph Hellwig
Most users want the generic device, so store that in struct nvme_dev instead of the pci_dev. This also happens to be a nice step towards making some code reusable for non-PCI transports. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-22nvme: consolidate synchronous command submission helpersChristoph Hellwig
Note that we keep the unused timeout argument, but allow callers to pass 0 instead of a timeout if they want the default. This will allow adding a timeout to the pass through path later on. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-20loop: remove (now) unused 'out' labelJens Axboe
gcc, righfully, complains: drivers/block/loop.c:1369:1: warning: label 'out' defined but not used [-Wunused-label] Kill it. Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-20s390/block/dasd: remove obsolete while -EBUSY loopJarod Wilson
With the mutex_trylock bit gone from blkdev_reread_part(), the retry logic in dasd_scan_partitions() shouldn't be necessary. CC: Christoph Hellwig <hch@infradead.org> CC: Jens Axboe <axboe@kernel.dk> CC: Tejun Heo <tj@kernel.org> CC: Alexander Viro <viro@zeniv.linux.org.uk> CC: Markus Pargmann <mpa@pengutronix.de> CC: Stefan Weinhuber <wein@de.ibm.com> CC: Stefan Haberland <stefan.haberland@de.ibm.com> CC: Sebastian Ott <sebott@linux.vnet.ibm.com> CC: Fabian Frederick <fabf@skynet.be> CC: Ming Lei <ming.lei@canonical.com> CC: David Herrmann <dh.herrmann@gmail.com> CC: Andrew Morton <akpm@linux-foundation.org> CC: Peter Zijlstra <peterz@infradead.org> CC: nbd-general@lists.sourceforge.net CC: linux-s390@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Sebastian Ott <sebott@linux.vnet.ibm.com> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jarod Wilson <jarod@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-20block: dasd_genhd: convert to blkdev_reread_partMing Lei
Also remove the obsolete comment. Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Jarod Wilson <jarod@redhat.com> Acked-by: Jarod Wilson <jarod@redhat.com> Acked-by: Sebastian Ott <sebott@linux.vnet.ibm.com> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-20block: nbd: convert to blkdev_reread_part()Ming Lei
Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Jarod Wilson <jarod@redhat.com> Acked-by: Jarod Wilson <jarod@redhat.com> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-20block: loop: fix another reread part failureMing Lei
loop_clr_fd() can be run piggyback with lo_release(), and under this situation, reread partition may always fail because bd_mutex has been held already. This patch detects the situation by the reference count, and call __blkdev_reread_part() to avoid acquiring the lock again. In the meantime, this patch switches to new kernel APIs of blkdev_reread_part() and __blkdev_reread_part(). Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Jarod Wilson <jarod@redhat.com> Acked-by: Jarod Wilson <jarod@redhat.com> Signed-off-by: Jarod Wilson <jarod@redhat.com> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-20block: loop: don't hold lo_ctl_mutex in lo_openMing Lei
The lo_ctl_mutex is held for running all ioctl handlers, and in some ioctl handlers, ioctl_by_bdev(BLKRRPART) is called for rereading partitions, which requires bd_mutex. So it is easy to cause failure because trylock(bd_mutex) may fail inside blkdev_reread_part(), and follows the lock context: blkid or other application: ->open() ->mutex_lock(bd_mutex) ->lo_open() ->mutex_lock(lo_ctl_mutex) losetup(set fd ioctl): ->mutex_lock(lo_ctl_mutex) ->ioctl_by_bdev(BLKRRPART) ->trylock(bd_mutex) This patch trys to eliminate the ABBA lock dependency by removing lo_ctl_mutext in lo_open() with the following approach: 1) make lo_refcnt as atomic_t and avoid acquiring lo_ctl_mutex in lo_open(): - for open vs. add/del loop, no any problem because of loop_index_mutex - freeze request queue during clr_fd, so I/O can't come until clearing fd is completed, like the effect of holding lo_ctl_mutex in lo_open - both open() and release() have been serialized by bd_mutex already 2) don't hold lo_ctl_mutex for decreasing/checking lo_refcnt in lo_release(), then lo_ctl_mutex is only required for the last release. Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Jarod Wilson <jarod@redhat.com> Acked-by: Jarod Wilson <jarod@redhat.com> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-20Merge branch 'for-4.2/core' into for-4.2/driversJens Axboe
We need the blkdev_reread_part() changes for drivers to adapt.
2015-05-20block: replace trylock with mutex_lock in blkdev_reread_part()Ming Lei
The only possible problem of using mutex_lock() instead of trylock is about deadlock. If there aren't any locks held before calling blkdev_reread_part(), deadlock can't be caused by this conversion. If there are locks held before calling blkdev_reread_part(), and if these locks arn't required in open, close handler and I/O path, deadlock shouldn't be caused too. Both user space's ioctl(BLKRRPART) and md_setup_drive() from init/do_mounts_md.c belongs to the 1st case, so the conversion is safe for the two cases. For loop, the previous patches in this pathset has fixed the ABBA lock dependency, so the conversion is OK. For nbd, tx_lock is held when calling the function: - both open and release won't hold the lock - when blkdev_reread_part() is run, I/O thread has been stopped already, so tx_lock won't be acquired in I/O path at that time. - so the conversion won't cause deadlock for nbd For dasd, both dasd_open(), dasd_release() and request function don't acquire any mutex/semphone, so the conversion should be safe. Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Jarod Wilson <jarod@redhat.com> Acked-by: Jarod Wilson <jarod@redhat.com> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-20block: export blkdev_reread_part() and __blkdev_reread_part()Jarod Wilson
This patch exports blkdev_reread_part() for block drivers, also introduce __blkdev_reread_part(). For some drivers, such as loop, reread of partitions can be run from the release path, and bd_mutex may already be held prior to calling ioctl_by_bdev(bdev, BLKRRPART, 0), so introduce __blkdev_reread_part for use in such cases. CC: Christoph Hellwig <hch@lst.de> CC: Jens Axboe <axboe@kernel.dk> CC: Tejun Heo <tj@kernel.org> CC: Alexander Viro <viro@zeniv.linux.org.uk> CC: Markus Pargmann <mpa@pengutronix.de> CC: Stefan Weinhuber <wein@de.ibm.com> CC: Stefan Haberland <stefan.haberland@de.ibm.com> CC: Sebastian Ott <sebott@linux.vnet.ibm.com> CC: Fabian Frederick <fabf@skynet.be> CC: Ming Lei <ming.lei@canonical.com> CC: David Herrmann <dh.herrmann@gmail.com> CC: Andrew Morton <akpm@linux-foundation.org> CC: Peter Zijlstra <peterz@infradead.org> CC: nbd-general@lists.sourceforge.net CC: linux-s390@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jarod Wilson <jarod@redhat.com> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-19suspend: simplify block I/O handlingChristoph Hellwig
Stop abusing struct page functionality and the swap end_io handler, and instead add a modified version of the blk-lib.c bio_batch helpers. Also move the block I/O code into swap.c as they are directly tied into each other. Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: Pavel Machek <pavel@ucw.cz> Tested-by: Ming Lin <mlin@kernel.org> Acked-by: Pavel Machek <pavel@ucw.cz> Acked-by: Rafael J. Wysocki <rjw@rjwysocki.net> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-19block: collapse bio bit spaceJens Axboe
Various previous patches removed bits and left holes, collapse them all. Leave the reset start bit where it is, we don't need to change that. Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-19block: remove unused BIO_RW_BLOCK and BIO_EOF flagsChristoph Hellwig
Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-19block: remove BIO_EOPNOTSUPPChristoph Hellwig
Since the big barrier rewrite/removal in 2007 we never fail FLUSH or FUA requests, which means we can remove the magic BIO_EOPNOTSUPP flag to help propagating those to the buffer_head layer. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-19nvme: disable irqs in nvme_freeze_queuesChristoph Hellwig
The queue_lock needs to be taken with irqs disabled. This is mostly due to the old pre blk-mq usage pattern, but we've also picked it up in most of the few places where we use the queue_lock with blk-mq. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-19block: use an atomic_t for mq_freeze_depthChristoph Hellwig
lockdep gets unhappy about the not disabling irqs when using the queue_lock around it. Instead of trying to fix that up just switch to an atomic_t and get rid of the lock. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-18cciss: correct the non-resettable board listTomas Henzl
The hpsa driver carries a more recent version, copy the table from there. Signed-off-by: Tomas Henzl <thenzl@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-18cciss: remove duplicate entries from board_type structTomas Henzl
and devices not supported by this driver from unresettable list Signed-off-by: Tomas Henzl <thenzl@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-08blk-mq: make plug work for mutiple disks and queuesShaohua Li
Last patch makes plug work for multiple queue case. However it only works for single disk case, because it assumes only one request in the plug list. If a task is accessing multiple disks, eg MD/DM, the assumption is wrong. Let blk_attempt_plug_merge() record request from the same queue. V2: use NULL parameter in !mq case. Fix a bug. Add comments in blk_attempt_plug_merge to make it less (hopefully) confusion. Cc: Jens Axboe <axboe@fb.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-08blk-mq: do limited block plug for multiple queue caseShaohua Li
plug is still helpful for workload with IO merge, but it can be harmful otherwise especially with multiple hardware queues, as there is (supposed) no lock contention in this case and plug can introduce latency. For multiple queues, we do limited plug, eg plug only if there is request merge. If a request doesn't have merge with following request, the requet will be dispatched immediately. V2: check blk_queue_nomerges() as suggested by Jeff. Cc: Jens Axboe <axboe@fb.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-08blk-mq: avoid re-initialize request which is failed in direct dispatchShaohua Li
If we directly issue a request and it fails, we use blk_mq_merge_queue_io(). But we already assigned bio to a request in blk_mq_bio_to_request. blk_mq_merge_queue_io shouldn't run blk_mq_bio_to_request again. Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-08blk-mq: fix plugging in blk_sq_make_requestJeff Moyer
The following appears in blk_sq_make_request: /* * If we have multiple hardware queues, just go directly to * one of those for sync IO. */ We clearly don't have multiple hardware queues, here! This comment was introduced with this commit 07068d5b8e (blk-mq: split make request handler for multi and single queue): We want slightly different behavior from them: - On single queue devices, we currently use the per-process plug for deferred IO and for merging. - On multi queue devices, we don't use the per-process plug, but we want to go straight to hardware for SYNC IO. The old code had this: use_plug = !is_flush_fua && ((q->nr_hw_queues == 1) || !is_sync); and that was converted to: use_plug = !is_flush_fua && !is_sync; which is not equivalent. For the single queue case, that second half of the && expression is always true. So, what I think was actually inteded follows (and this more closely matches what is done in blk_queue_bio). V2: delete the 'likely', which should not be a big deal Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-08sched: always use blk_schedule_flush_plug in io_schedule_outShaohua Li
block plug callback could sleep, so we introduce a parameter 'from_schedule' and corresponding drivers can use it to destinguish a schedule plug flush or a plug finish. Unfortunately io_schedule_out still uses blk_flush_plug(). This causes below output (Note, I added a might_sleep() in raid1_unplug to make it trigger faster, but the whole thing doesn't matter if I add might_sleep). In raid1/10, this can cause deadlock. This patch makes io_schedule_out always uses blk_schedule_flush_plug. This should only impact drivers (as far as I know, raid 1/10) which are sensitive to the 'from_schedule' parameter. [ 370.817949] ------------[ cut here ]------------ [ 370.817960] WARNING: CPU: 7 PID: 145 at ../kernel/sched/core.c:7306 __might_sleep+0x7f/0x90() [ 370.817969] do not call blocking ops when !TASK_RUNNING; state=2 set at [<ffffffff81092fcf>] prepare_to_wait+0x2f/0x90 [ 370.817971] Modules linked in: raid1 [ 370.817976] CPU: 7 PID: 145 Comm: kworker/u16:9 Tainted: G W 4.0.0+ #361 [ 370.817977] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.7.5-20140709_153802- 04/01/2014 [ 370.817983] Workqueue: writeback bdi_writeback_workfn (flush-9:1) [ 370.817985] ffffffff81cd83be ffff8800ba8cb298 ffffffff819dd7af 0000000000000001 [ 370.817988] ffff8800ba8cb2e8 ffff8800ba8cb2d8 ffffffff81051afc ffff8800ba8cb2c8 [ 370.817990] ffffffffa00061a8 000000000000041e 0000000000000000 ffff8800ba8cba28 [ 370.817993] Call Trace: [ 370.817999] [<ffffffff819dd7af>] dump_stack+0x4f/0x7b [ 370.818002] [<ffffffff81051afc>] warn_slowpath_common+0x8c/0xd0 [ 370.818004] [<ffffffff81051b86>] warn_slowpath_fmt+0x46/0x50 [ 370.818006] [<ffffffff81092fcf>] ? prepare_to_wait+0x2f/0x90 [ 370.818008] [<ffffffff81092fcf>] ? prepare_to_wait+0x2f/0x90 [ 370.818010] [<ffffffff810776ef>] __might_sleep+0x7f/0x90 [ 370.818014] [<ffffffffa0000c03>] raid1_unplug+0xd3/0x170 [raid1] [ 370.818024] [<ffffffff81421d9a>] blk_flush_plug_list+0x8a/0x1e0 [ 370.818028] [<ffffffff819e3550>] ? bit_wait+0x50/0x50 [ 370.818031] [<ffffffff819e21b0>] io_schedule_timeout+0x130/0x140 [ 370.818033] [<ffffffff819e3586>] bit_wait_io+0x36/0x50 [ 370.818034] [<ffffffff819e31b5>] __wait_on_bit+0x65/0x90 [ 370.818041] [<ffffffff8125b67c>] ? ext4_read_block_bitmap_nowait+0xbc/0x630 [ 370.818043] [<ffffffff819e3550>] ? bit_wait+0x50/0x50 [ 370.818045] [<ffffffff819e3302>] out_of_line_wait_on_bit+0x72/0x80 [ 370.818047] [<ffffffff810935e0>] ? autoremove_wake_function+0x40/0x40 [ 370.818050] [<ffffffff811de744>] __wait_on_buffer+0x44/0x50 [ 370.818053] [<ffffffff8125ae80>] ext4_wait_block_bitmap+0xe0/0xf0 [ 370.818058] [<ffffffff812975d6>] ext4_mb_init_cache+0x206/0x790 [ 370.818062] [<ffffffff8114bc6c>] ? lru_cache_add+0x1c/0x50 [ 370.818064] [<ffffffff81297c7e>] ext4_mb_init_group+0x11e/0x200 [ 370.818066] [<ffffffff81298231>] ext4_mb_load_buddy+0x341/0x360 [ 370.818068] [<ffffffff8129a1a3>] ext4_mb_find_by_goal+0x93/0x2f0 [ 370.818070] [<ffffffff81295b54>] ? ext4_mb_normalize_request+0x1e4/0x5b0 [ 370.818072] [<ffffffff8129ab67>] ext4_mb_regular_allocator+0x67/0x460 [ 370.818074] [<ffffffff81295b54>] ? ext4_mb_normalize_request+0x1e4/0x5b0 [ 370.818076] [<ffffffff8129ca4b>] ext4_mb_new_blocks+0x4cb/0x620 [ 370.818079] [<ffffffff81290956>] ext4_ext_map_blocks+0x4c6/0x14d0 [ 370.818081] [<ffffffff812a4d4e>] ? ext4_es_lookup_extent+0x4e/0x290 [ 370.818085] [<ffffffff8126399d>] ext4_map_blocks+0x14d/0x4f0 [ 370.818088] [<ffffffff81266fbd>] ext4_writepages+0x76d/0xe50 [ 370.818094] [<ffffffff81149691>] do_writepages+0x21/0x50 [ 370.818097] [<ffffffff811d5c00>] __writeback_single_inode+0x60/0x490 [ 370.818099] [<ffffffff811d630a>] writeback_sb_inodes+0x2da/0x590 [ 370.818103] [<ffffffff811abf4b>] ? trylock_super+0x1b/0x50 [ 370.818105] [<ffffffff811abf4b>] ? trylock_super+0x1b/0x50 [ 370.818107] [<ffffffff811d665f>] __writeback_inodes_wb+0x9f/0xd0 [ 370.818109] [<ffffffff811d69db>] wb_writeback+0x34b/0x3c0 [ 370.818111] [<ffffffff811d70df>] bdi_writeback_workfn+0x23f/0x550 [ 370.818116] [<ffffffff8106bbd8>] process_one_work+0x1c8/0x570 [ 370.818117] [<ffffffff8106bb5b>] ? process_one_work+0x14b/0x570 [ 370.818119] [<ffffffff8106c09b>] worker_thread+0x11b/0x470 [ 370.818121] [<ffffffff8106bf80>] ? process_one_work+0x570/0x570 [ 370.818124] [<ffffffff81071868>] kthread+0xf8/0x110 [ 370.818126] [<ffffffff81071770>] ? kthread_create_on_node+0x210/0x210 [ 370.818129] [<ffffffff819e9322>] ret_from_fork+0x42/0x70 [ 370.818131] [<ffffffff81071770>] ? kthread_create_on_node+0x210/0x210 [ 370.818132] ---[ end trace 7b4deb71e68b6605 ]--- V2: don't change ->in_iowait Cc: NeilBrown <neilb@suse.de> Signed-off-by: Shaohua Li <shli@fb.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-05-08blk: clean up plugShaohua Li
Current code looks like inner plug gets flushed with a blk_finish_plug(). Actually it's a nop. All requests/callbacks are added to current->plug, while only outmost plug is assigned to current->plug. So inner plug always has empty request/callback list, which makes blk_flush_plug_list() a nop. This tries to make the code more clear. Signed-off-by: Shaohua Li <shli@fb.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>