- 26 9月, 2014 7 次提交
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由 Ming Lei 提交于
This patch supports to run one single flush machinery for each blk-mq dispatch queue, so that: - current init_request and exit_request callbacks can cover flush request too, then the buggy copying way of initializing flush request's pdu can be fixed - flushing performance gets improved in case of multi hw-queue In fio sync write test over virtio-blk(4 hw queues, ioengine=sync, iodepth=64, numjobs=4, bs=4K), it is observed that througput gets increased a lot over my test environment: - throughput: +70% in case of virtio-blk over null_blk - throughput: +30% in case of virtio-blk over SSD image The multi virtqueue feature isn't merged to QEMU yet, and patches for the feature can be found in below tree: git://kernel.ubuntu.com/ming/qemu.git v2.1.0-mq.4 And simply passing 'num_queues=4 vectors=5' should be enough to enable multi queue(quad queue) feature for QEMU virtio-blk. Suggested-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NMing Lei <ming.lei@canonical.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Ming Lei 提交于
This patch adds 'blk_mq_ctx' parameter to blk_get_flush_queue(), so that this function can find the corresponding blk_flush_queue bound with current mq context since the flush queue will become per hw-queue. For legacy queue, the parameter can be simply 'NULL'. For multiqueue case, the parameter should be set as the context from which the related request is originated. With this context info, the hw queue and related flush queue can be found easily. Signed-off-by: NMing Lei <ming.lei@canonical.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Ming Lei 提交于
Now mission of the two helpers is over, and just call blk_alloc_flush_queue() and blk_free_flush_queue() directly. Signed-off-by: NMing Lei <ming.lei@canonical.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Ming Lei 提交于
This patch introduces 'struct blk_flush_queue' and puts all flush machinery related fields into this structure, so that - flush implementation details aren't exposed to driver - it is easy to convert to per dispatch-queue flush machinery This patch is basically a mechanical replacement. Reviewed-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NMing Lei <ming.lei@canonical.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Ming Lei 提交于
These two temporary functions are introduced for holding flush initialization and de-initialization, so that we can introduce 'flush queue' easier in the following patch. And once 'flush queue' and its allocation/free functions are ready, they will be removed for sake of code readability. Reviewed-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NMing Lei <ming.lei@canonical.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Ming Lei 提交于
It is reasonable to allocate flush req in blk_mq_init_flush(). Reviewed-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NMing Lei <ming.lei@canonical.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Ming Lei 提交于
Failure of initializing one hctx isn't handled, so this patch introduces blk_mq_init_hctx() and its pair to handle it explicitly. Also this patch makes code cleaner. Reviewed-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NMing Lei <ming.lei@canonical.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 23 9月, 2014 14 次提交
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由 Christoph Hellwig 提交于
Signed-off-by: NChristoph Hellwig <hch@lst.de> Moved blk_mq_rq_timed_out() definition to the private blk-mq.h header. Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Jens Axboe 提交于
It's not uncommon for crash dump kernels to be limited to 128MB or something low in that area. This is normally not a problem for devices as we don't use that much memory, but for some shared SCSI setups with huge queue depths, it can potentially fill most of memory with tons of request allocations. blk-mq does scale back when it fails to allocate memory, but it scales back just enough so that blk-mq succeeds. This could still leave the system with not enough memory to make any real progress. Check if we are in a kdump environment and limit the hardware queues and tag depth. Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Ming Lei 提交于
This patch removes two unnecessary blk_clear_rq_complete(), the REQ_ATOM_COMPLETE flag is cleared inside blk_mq_start_request(), so: - The blk_clear_rq_complete() in blk_flush_restore_request() needn't because the request will be freed later, and clearing it here may open a small race window with timeout. - The blk_clear_rq_complete() in blk_mq_requeue_request() isn't necessary too, even though REQ_ATOM_STARTED is cleared in __blk_mq_requeue_request(), in theory it still may cause a small race window with timeout since the two clear_bit() may be reordered. Signed-off-by: NMing Lei <ming.lei@canoical.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
Allow blk-mq to pass an argument to the timeout handler to indicate if we're timing out a reserved or regular command. For many drivers those need to be handled different. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
Duplicate the (small) timeout handler in blk-mq so that we can pass arguments more easily to the driver timeout handler. This enables the next patch. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
Don't do a kmalloc from timer to handle timeouts, chances are we could be under heavy load or similar and thus just miss out on the timeouts. Fortunately it is very easy to just iterate over all in use tags, and doing this properly actually cleans up the blk_mq_busy_iter API as well, and prepares us for the next patch by passing a reserved argument to the iterator. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
Now that we've changed the driver API on the submission side use the opportunity to fix up the name on the completion side to fit into the general scheme. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
When we call blk_mq_start_request from the core blk-mq code before calling into ->queue_rq there is a racy window where the timeout handler can hit before we've fully set up the driver specific part of the command. Move the call to blk_mq_start_request into the driver so the driver can start the request only once it is fully set up. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
Pass an explicit parameter for the last request in a batch to ->queue_rq instead of using a request flag. Besides being a cleaner and non-stateful interface this is also required for the next patch, which fixes the blk-mq I/O submission code to not start a time too early. Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Jens Axboe 提交于
When requests are retried due to hw or sw resource shortages, we often stop the associated hardware queue. So ensure that we restart the queues when running the requeue work, otherwise the queue run will be a no-op. Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Jens Axboe 提交于
__blk_mq_alloc_rq_maps() can be invoked multiple times, if we scale back the queue depth if we are low on memory. So don't clear set->tags when we fail, this is handled directly in the parent function, blk_mq_alloc_tag_set(). Reported-by: NRobert Elliott <Elliott@hp.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
We should not insert requests into the flush state machine from blk_mq_insert_request. All incoming flush requests come through blk_{m,s}q_make_request and are handled there, while blk_execute_rq_nowait should only be called for BLOCK_PC requests. All other callers deal with requests that already went through the flush statemchine and shouldn't be reinserted into it. Reported-by: NRobert Elliott <Elliott@hp.com> Debugged-by: NMing Lei <ming.lei@canonical.com> Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 David Hildenbrand 提交于
This patch should fix the bug reported in https://lkml.org/lkml/2014/9/11/249. We have to initialize at least the atomic_flags and the cmd_flags when allocating storage for the requests. Otherwise blk_mq_timeout_check() might dereference uninitialized pointers when racing with the creation of a request. Also move the reset of cmd_flags for the initializing code to the point where a request is freed. So we will never end up with pending flush request indicators that might trigger dereferences of invalid pointers in blk_mq_timeout_check(). Cc: stable@vger.kernel.org Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com> Reported-by: NPaulo De Rezende Pinatti <ppinatti@linux.vnet.ibm.com> Tested-by: NPaulo De Rezende Pinatti <ppinatti@linux.vnet.ibm.com> Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Jens Axboe 提交于
When we start the request, we set the deadline and flip the bits marking the request as started and non-complete. However, it's important that the deadline store is ordered before flipping the bits, otherwise we could have a small window where the request is marked started but with an invalid deadline. This can confuse the timeout handling. Suggested-by: NMing Lei <tom.leiming@gmail.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 10 9月, 2014 1 次提交
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由 Jens Axboe 提交于
If we are running in a kdump environment, resources are scarce. For some SCSI setups with a huge set of shared tags, we run out of memory allocating what the drivers is asking for. So implement a scale back logic to reduce the tag depth for those cases, allowing the driver to successfully load. We should extend this to detect low memory situations, and implement a sane fallback for those (1 queue, 64 tags, or something like that). Tested-by: NRobert Elliott <elliott@hp.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 04 9月, 2014 1 次提交
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由 Robert Elliott 提交于
In blk-mq.c blk_mq_alloc_tag_set, if: set->tags = kmalloc_node() succeeds, but one of the blk_mq_init_rq_map() calls fails, goto out_unwind; needs to free set->tags so the caller is not obligated to do so. None of the current callers (null_blk, virtio_blk, virtio_blk, or the forthcoming scsi-mq) do so. set->tags needs to be set to NULL after doing so, so other tag cleanup logic doesn't try to free a stale pointer later. Also set it to NULL in blk_mq_free_tag_set. Tested with error injection on the forthcoming scsi-mq + hpsa combination. Signed-off-by: NRobert Elliott <elliott@hp.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 29 8月, 2014 1 次提交
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由 Joe Lawrence 提交于
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: NJoe 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: NJeff Moyer <jmoyer@redhat.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 23 8月, 2014 1 次提交
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由 Tony Battersby 提交于
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: NTony Battersby <tonyb@cybernetics.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 22 8月, 2014 3 次提交
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由 Tejun Heo 提交于
While converting to percpu_ref for freezing, add703fd ("blk-mq: use percpu_ref for mq usage count") incorrectly made blk_mq_freeze_queue() misbehave when freezing is nested due to percpu_ref_kill() being invoked on an already killed ref. Fix it by making blk_mq_freeze_queue() kill and kick the queue only for the outermost freeze attempt. All the nested ones can simply wait for the ref to reach zero. While at it, remove unnecessary @wake initialization from blk_mq_unfreeze_queue(). Signed-off-by: NTejun Heo <tj@kernel.org> Reported-by: NMing Lei <ming.lei@canonical.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Jens Axboe 提交于
Just grammar or spelling errors, nothing major. Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Jens Axboe 提交于
blk-mq uses BLK_MQ_F_SHOULD_MERGE, as set by the driver at init time, to determine whether it should merge IO or not. However, this could also be disabled by the admin, if merging is switched off through sysfs. So check the general queue state as well before attempting to merge IO. Reported-by: NRob Elliott <Elliott@hp.com> Tested-by: NRob Elliott <Elliott@hp.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 16 8月, 2014 1 次提交
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由 Ming Lei 提交于
Before doing queue release, the queue has been freezed already by blk_cleanup_queue(), so needn't to freeze queue for deleting tag set. This patch fixes the WARNING of "percpu_ref_kill() called more than once!" which is triggered during unloading block driver. Cc: Tejun Heo <tj@kernel.org> Signed-off-by: NMing Lei <ming.lei@canonical.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 02 7月, 2014 5 次提交
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由 Tejun Heo 提交于
Currently, blk-mq uses a percpu_counter to keep track of how many usages are in flight. The percpu_counter is drained while freezing to ensure that no usage is left in-flight after freezing is complete. blk_mq_queue_enter/exit() and blk_mq_[un]freeze_queue() implement this per-cpu gating mechanism. This type of code has relatively high chance of subtle bugs which are extremely difficult to trigger and it's way too hairy to be open coded in blk-mq. percpu_ref can serve the same purpose after the recent changes. This patch replaces the open-coded per-cpu usage counting and draining mechanism with percpu_ref. blk_mq_queue_enter() performs tryget_live on the ref and exit() performs put. blk_mq_freeze_queue() kills the ref and waits until the reference count reaches zero. blk_mq_unfreeze_queue() revives the ref and wakes up the waiters. Signed-off-by: NTejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Nicholas A. Bellinger <nab@linux-iscsi.org> Cc: Kent Overstreet <kmo@daterainc.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Tejun Heo 提交于
Keeping __blk_mq_drain_queue() as a separate function doesn't buy us anything and it's gonna be further simplified. Let's flatten it into its caller. This patch doesn't make any functional change. Signed-off-by: NTejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Nicholas A. Bellinger <nab@linux-iscsi.org> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Tejun Heo 提交于
blk_mq freezing is entangled with generic bypassing which bypasses blkcg and io scheduler and lets IO requests fall through the block layer to the drivers in FIFO order. This allows forward progress on IOs with the advanced features disabled so that those features can be configured or altered without worrying about stalling IO which may lead to deadlock through memory allocation. However, generic bypassing doesn't quite fit blk-mq. blk-mq currently doesn't make use of blkcg or ioscheds and it maps bypssing to freezing, which blocks request processing and drains all the in-flight ones. This causes problems as bypassing assumes that request processing is online. blk-mq works around this by conditionally allowing request processing for the problem case - during queue initialization. Another weirdity is that except for during queue cleanup, bypassing started on the generic side prevents blk-mq from processing new requests but doesn't drain the in-flight ones. This shouldn't break anything but again highlights that something isn't quite right here. The root cause is conflating blk-mq freezing and generic bypassing which are two different mechanisms. The only intersecting purpose that they serve is during queue cleanup. Let's properly separate blk-mq freezing from generic bypassing and simply use it where necessary. * request_queue->mq_freeze_depth is added and blk_mq_[un]freeze_queue() now operate on this counter instead of ->bypass_depth. The replacement for QUEUE_FLAG_BYPASS isn't added but the counter is tested directly. This will be further updated by later changes. * blk_mq_drain_queue() is dropped and "__" prefix is dropped from blk_mq_freeze_queue(). Queue cleanup path now calls blk_mq_freeze_queue() directly. * blk_queue_enter()'s fast path condition is simplified to simply check @q->mq_freeze_depth. Previously, the condition was !blk_queue_dying(q) && (!blk_queue_bypass(q) || !blk_queue_init_done(q)) mq_freeze_depth is incremented right after dying is set and blk_queue_init_done() exception isn't necessary as blk-mq doesn't start frozen, which only leaves the blk_queue_bypass() test which can be replaced by @q->mq_freeze_depth test. This change simplifies the code and reduces confusion in the area. Signed-off-by: NTejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Nicholas A. Bellinger <nab@linux-iscsi.org> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Tejun Heo 提交于
Currently, both blk_queue_bypass_start() and blk_mq_freeze_queue() skip queue draining if bypass_depth was already above zero. The assumption is that the one which bumped the bypass_depth should have performed draining already; however, there's nothing which prevents a new instance of bypassing/freezing from starting before the previous one finishes draining. The current code may allow the later bypassing/freezing instances to complete while there still are in-flight requests which haven't finished draining. Fix it by draining regardless of bypass_depth. We still skip draining from blk_queue_bypass_start() while the queue is initializing to avoid introducing excessive delays during boot. INIT_DONE setting is moved above the initial blk_queue_bypass_end() so that bypassing attempts can't slip inbetween. Signed-off-by: NTejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Nicholas A. Bellinger <nab@linux-iscsi.org> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Tejun Heo 提交于
blk-mq uses a percpu_counter to keep track of how many usages are in flight. The percpu_counter is drained while freezing to ensure that no usage is left in-flight after freezing is complete. blk_mq_queue_enter/exit() and blk_mq_[un]freeze_queue() implement this per-cpu gating mechanism; unfortunately, it contains a subtle bug - smp_wmb() in blk_mq_queue_enter() doesn't prevent prevent the cpu from fetching @q->bypass_depth before incrementing @q->mq_usage_counter and if freezing happens inbetween the caller can slip through and freezing can be complete while there are active users. Use smp_mb() instead so that bypass_depth and mq_usage_counter modifications and tests are properly interlocked. Signed-off-by: NTejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Nicholas A. Bellinger <nab@linux-iscsi.org> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 25 6月, 2014 1 次提交
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由 Jens Axboe 提交于
Currently it calls __blk_mq_run_hw_queue(), which depends on the CPU placement being correct. This means it's not possible to call blk_mq_start_hw_queues(q) from a context that is correct for all queues, leading to triggering the WARN_ON(!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask)); in __blk_mq_run_hw_queue(). Reported-by: NMing Lei <tom.leiming@gmail.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 14 6月, 2014 2 次提交
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由 Christoph Hellwig 提交于
Signed-off-by: NChristoph Hellwig <hch@lst.de> Signed-off-by: NJens Axboe <axboe@fb.com>
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由 Christoph Hellwig 提交于
If we need to drain a queue we need to run all queues, even if they are marked stopped to make sure the driver has a chance to error out on all queued requests. This fixes surprise removal with scsi-mq. Reported-by: NBart Van Assche <bvanassche@acm.org> Tested-by: NBart Van Assche <bvanassche@acm.org> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 10 6月, 2014 1 次提交
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由 Ming Lei 提交于
This way will become consistent with non-mq case, also avoid to update rq->deadline twice for mq. The comment said: "We do this early, to ensure we are on the right CPU.", but no percpu stuff is used in blk_add_timer(), so it isn't necessary. Even when inserting from plug list, there is no such guarantee at all. Signed-off-by: NMing Lei <tom.leiming@gmail.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 09 6月, 2014 1 次提交
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由 Jens Axboe 提交于
The blk-mq core only initializes this if io stats are enabled, since blk-mq only reads the field in that case. But drivers could potentially use it internally, so ensure that we always set it to the current time when the request is allocated. Reported-by: NMing Lei <tom.leiming@gmail.com> Signed-off-by: NJens Axboe <axboe@fb.com>
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- 07 6月, 2014 1 次提交
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由 Jens Axboe 提交于
It'll be used in blk_mq_start_request() to set a potential timeout for the request, so clear it to zero at alloc time to ensure that we know if someone has set it or not. Fixes random early timeouts on NVMe testing. Signed-off-by: NJens Axboe <axboe@fb.com>
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