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2021-09-13blk-mq: avoid to iterate over stale requestMing Lei1-1/+1
blk-mq can't run allocating driver tag and updating ->rqs[tag] atomically, meantime blk-mq doesn't clear ->rqs[tag] after the driver tag is released. So there is chance to iterating over one stale request just after the tag is allocated and before updating ->rqs[tag]. scsi_host_busy_iter() calls scsi_host_check_in_flight() to count scsi in-flight requests after scsi host is blocked, so no new scsi command can be marked as SCMD_STATE_INFLIGHT. However, driver tag allocation still can be run by blk-mq core. One request is marked as SCMD_STATE_INFLIGHT, but this request may have been kept in another slot of ->rqs[], meantime the slot can be allocated out but ->rqs[] isn't updated yet. Then this in-flight request is counted twice as SCMD_STATE_INFLIGHT. This way causes trouble in handling scsi error. Fixes the issue by not iterating over stale request. Cc: linux-scsi@vger.kernel.org Cc: "Martin K. Petersen" <martin.petersen@oracle.com> Reported-by: luojiaxing <luojiaxing@huawei.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20210906065003.439019-1-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-05-24blk-mq: Use request queue-wide tags for tagset-wide sbitmapJohn Garry1-6/+5
The tags used for an IO scheduler are currently per hctx. As such, when q->nr_hw_queues grows, so does the request queue total IO scheduler tag depth. This may cause problems for SCSI MQ HBAs whose total driver depth is fixed. Ming and Yanhui report higher CPU usage and lower throughput in scenarios where the fixed total driver tag depth is appreciably lower than the total scheduler tag depth: https://lore.kernel.org/linux-block/440dfcfc-1a2c-bd98-1161-cec4d78c6dfc@huawei.com/T/#mc0d6d4f95275a2743d1c8c3e4dc9ff6c9aa3a76b In that scenario, since the scheduler tag is got first, much contention is introduced since a driver tag may not be available after we have got the sched tag. Improve this scenario by introducing request queue-wide tags for when a tagset-wide sbitmap is used. The static sched requests are still allocated per hctx, as requests are initialised per hctx, as in blk_mq_init_request(..., hctx_idx, ...) -> set->ops->init_request(.., hctx_idx, ...). For simplicity of resizing the request queue sbitmap when updating the request queue depth, just init at the max possible size, so we don't need to deal with the possibly with swapping out a new sbitmap for old if we need to grow. Signed-off-by: John Garry <john.garry@huawei.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/1620907258-30910-3-git-send-email-john.garry@huawei.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-05-24blk-mq: Some tag allocation code refactoringJohn Garry1-21/+33
The tag allocation code to alloc the sbitmap pairs is common for regular bitmaps tags and shared sbitmap, so refactor into a common function. Also remove superfluous "flags" argument from blk_mq_init_shared_sbitmap(). Signed-off-by: John Garry <john.garry@huawei.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/1620907258-30910-2-git-send-email-john.garry@huawei.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-05-24blk-mq: clear stale request in tags->rq[] before freeing one request poolMing Lei1-2/+7
refcount_inc_not_zero() in bt_tags_iter() still may read one freed request. Fix the issue by the following approach: 1) hold a per-tags spinlock when reading ->rqs[tag] and calling refcount_inc_not_zero in bt_tags_iter() 2) clearing stale request referred via ->rqs[tag] before freeing request pool, the per-tags spinlock is held for clearing stale ->rq[tag] So after we cleared stale requests, bt_tags_iter() won't observe freed request any more, also the clearing will wait for pending request reference. The idea of clearing ->rqs[] is borrowed from John Garry's previous patch and one recent David's patch. Tested-by: John Garry <john.garry@huawei.com> Reviewed-by: David Jeffery <djeffery@redhat.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20210511152236.763464-4-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-05-24blk-mq: grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iterMing Lei1-11/+33
Grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iter(), and this way will prevent the request from being re-used when ->fn is running. The approach is same as what we do during handling timeout. Fix request use-after-free(UAF) related with completion race or queue releasing: - If one rq is referred before rq->q is frozen, then queue won't be frozen before the request is released during iteration. - If one rq is referred after rq->q is frozen, refcount_inc_not_zero() will return false, and we won't iterate over this request. However, still one request UAF not covered: refcount_inc_not_zero() may read one freed request, and it will be handled in next patch. Tested-by: John Garry <john.garry@huawei.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20210511152236.763464-3-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-04-06blk-mq: Always use blk_mq_is_sbitmap_sharedNikolay Borisov1-2/+2
Signed-off-by: Nikolay Borisov <nborisov@suse.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com> Link: https://lore.kernel.org/r/20210311081713.2763171-1-nborisov@suse.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-03-25blk-mq: Sentence reconstruct for better readabilityBhaskar Chowdhury1-2/+2
Sentence reconstruction for better readability. Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-09-29block-mq: fix comments in blk_mq_queue_tag_busy_iteryangerkun1-3/+1
'f5bbbbe4d635 ("blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter")' introduce a bug what we may sleep between rcu lock. Then '530ca2c9bd69 ("blk-mq: Allow blocking queue tag iter callbacks")' fix it by get request_queue's ref. And 'a9a808084d6a ("block: Remove the synchronize_rcu() call from __blk_mq_update_nr_hw_queues()")' remove the synchronize_rcu in __blk_mq_update_nr_hw_queues. We need update the confused comments in blk_mq_queue_tag_busy_iter. Signed-off-by: yangerkun <yangerkun@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-09-11blk-mq: always allow reserved allocation in hctx_may_queueMing Lei1-1/+2
NVMe shares tagset between fabric queue and admin queue or between connect_q and NS queue, so hctx_may_queue() can be called to allocate request for these queues. Tags can be reserved in these tagset. Before error recovery, there is often lots of in-flight requests which can't be completed, and new reserved request may be needed in error recovery path. However, hctx_may_queue() can always return false because there is too many in-flight requests which can't be completed during error handling. Finally, nothing can proceed. Fix this issue by always allowing reserved tag allocation in hctx_may_queue(). This is reasonable because reserved tags are supposed to always be available. Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Cc: David Milburn <dmilburn@redhat.com> Cc: Ewan D. Milne <emilne@redhat.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-09-04blk-mq: Record active_queues_shared_sbitmap per tag_set for when using ↵John Garry1-8/+25
shared sbitmap For when using a shared sbitmap, no longer should the number of active request queues per hctx be relied on for when judging how to share the tag bitmap. Instead maintain the number of active request queues per tag_set, and make the judgement based on that. Originally-from: Kashyap Desai <kashyap.desai@broadcom.com> Signed-off-by: John Garry <john.garry@huawei.com> Tested-by: Don Brace<don.brace@microsemi.com> #SCSI resv cmds patches used Tested-by: Douglas Gilbert <dgilbert@interlog.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-09-04blk-mq: Facilitate a shared sbitmap per tagsetJohn Garry1-4/+47
Some SCSI HBAs (such as HPSA, megaraid, mpt3sas, hisi_sas_v3 ..) support multiple reply queues with single hostwide tags. In addition, these drivers want to use interrupt assignment in pci_alloc_irq_vectors(PCI_IRQ_AFFINITY). However, as discussed in [0], CPU hotplug may cause in-flight IO completion to not be serviced when an interrupt is shutdown. That problem is solved in commit bf0beec0607d ("blk-mq: drain I/O when all CPUs in a hctx are offline"). However, to take advantage of that blk-mq feature, the HBA HW queuess are required to be mapped to that of the blk-mq hctx's; to do that, the HBA HW queues need to be exposed to the upper layer. In making that transition, the per-SCSI command request tags are no longer unique per Scsi host - they are just unique per hctx. As such, the HBA LLDD would have to generate this tag internally, which has a certain performance overhead. However another problem is that blk-mq assumes the host may accept (Scsi_host.can_queue * #hw queue) commands. In commit 6eb045e092ef ("scsi: core: avoid host-wide host_busy counter for scsi_mq"), the Scsi host busy counter was removed, which would stop the LLDD being sent more than .can_queue commands; however, it should still be ensured that the block layer does not issue more than .can_queue commands to the Scsi host. To solve this problem, introduce a shared sbitmap per blk_mq_tag_set, which may be requested at init time. New flag BLK_MQ_F_TAG_HCTX_SHARED should be set when requesting the tagset to indicate whether the shared sbitmap should be used. Even when BLK_MQ_F_TAG_HCTX_SHARED is set, a full set of tags and requests are still allocated per hctx; the reason for this is that if tags and requests were only allocated for a single hctx - like hctx0 - it may break block drivers which expect a request be associated with a specific hctx, i.e. not always hctx0. This will introduce extra memory usage. This change is based on work originally from Ming Lei in [1] and from Bart's suggestion in [2]. [0] https://lore.kernel.org/linux-block/alpine.DEB.2.21.1904051331270.1802@nanos.tec.linutronix.de/ [1] https://lore.kernel.org/linux-block/20190531022801.10003-1-ming.lei@redhat.com/ [2] https://lore.kernel.org/linux-block/ff77beff-5fd9-9f05-12b6-826922bace1f@huawei.com/T/#m3db0a602f095cbcbff27e9c884d6b4ae826144be Signed-off-by: John Garry <john.garry@huawei.com> Tested-by: Don Brace<don.brace@microsemi.com> #SCSI resv cmds patches used Tested-by: Douglas Gilbert <dgilbert@interlog.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-09-04blk-mq: Use pointers for blk_mq_tags bitmap tagsJohn Garry1-19/+22
Introduce pointers for the blk_mq_tags regular and reserved bitmap tags, with the goal of later being able to use a common shared tag bitmap across all HW contexts in a set. Signed-off-by: John Garry <john.garry@huawei.com> Tested-by: Don Brace<don.brace@microsemi.com> #SCSI resv cmds patches used Tested-by: Douglas Gilbert <dgilbert@interlog.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-09-04blk-mq: Pass flags for tag init/freeJohn Garry1-5/+7
Pass hctx/tagset flags argument down to blk_mq_init_tags() and blk_mq_free_tags() for selective init/free. For now, make it include the alloc policy flag, which can be evaluated when needed (in blk_mq_init_tags()). Signed-off-by: John Garry <john.garry@huawei.com> Tested-by: Douglas Gilbert <dgilbert@interlog.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-09-04blk-mq: Free tags in blk_mq_init_tags() upon errorHannes Reinecke1-8/+10
Since the tags are allocated in blk_mq_init_tags(), it's better practice to free in that same function upon error, rather than a callee which is to init the bitmap tags (blk_mq_init_tags()). [jpg: Split from an earlier patch with a new commit message] Signed-off-by: Hannes Reinecke <hare@suse.de> Signed-off-by: John Garry <john.garry@huawei.com> Tested-by: Douglas Gilbert <dgilbert@interlog.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-30blk-mq: move blk_mq_get_driver_tag into blk-mq.cMing Lei1-58/+0
blk_mq_get_driver_tag() is only used by blk-mq.c and is supposed to stay in blk-mq.c, so move it and preparing for cleanup code of get/put driver tag. Meantime hctx_may_queue() is moved to header file and it is fine since it is defined as inline always. No functional change. Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-29blk-mq: remove the BLK_MQ_REQ_INTERNAL flagChristoph Hellwig1-2/+2
Just check for a non-NULL elevator directly to make the code more clear. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-15blk-mq: Remove redundant 'return' statementBaolin Wang1-1/+1
The blk_mq_all_tag_iter() is a void function, thus remove the redundant 'return' statement in this function. Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-07blk-mq: fix blk_mq_all_tag_iterMing Lei1-3/+9
blk_mq_all_tag_iter() is added to iterate all requests, so we should fetch the request from ->static_rqs][] instead of ->rqs[] which is for holding in-flight request only. Fix it by adding flag of BT_TAG_ITER_STATIC_RQS. Fixes: bf0beec0607d ("blk-mq: drain I/O when all CPUs in a hctx are offline") Signed-off-by: Ming Lei <ming.lei@redhat.com> Tested-by: John Garry <john.garry@huawei.com> Cc: Dongli Zhang <dongli.zhang@oracle.com> Cc: Hannes Reinecke <hare@suse.de> Cc: Daniel Wagner <dwagner@suse.de> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-06-07blk-mq: split out a __blk_mq_get_driver_tag helperChristoph Hellwig1-0/+27
Allocation of the driver tag in the case of using a scheduler shares very little code with the "normal" tag allocation. Split out a new helper to streamline this path, and untangle it from the complex normal tag allocation. This way also avoids to fail driver tag allocation because of inactive hctx during cpu hotplug, and fixes potential hang risk. Fixes: bf0beec0607d ("blk-mq: drain I/O when all CPUs in a hctx are offline") Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Tested-by: John Garry <john.garry@huawei.com> Cc: Dongli Zhang <dongli.zhang@oracle.com> Cc: Hannes Reinecke <hare@suse.de> Cc: Daniel Wagner <dwagner@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-05-29blk-mq: drain I/O when all CPUs in a hctx are offlineMing Lei1-0/+8
Most of blk-mq drivers depend on managed IRQ's auto-affinity to setup up queue mapping. Thomas mentioned the following point[1]: "That was the constraint of managed interrupts from the very beginning: The driver/subsystem has to quiesce the interrupt line and the associated queue _before_ it gets shutdown in CPU unplug and not fiddle with it until it's restarted by the core when the CPU is plugged in again." However, current blk-mq implementation doesn't quiesce hw queue before the last CPU in the hctx is shutdown. Even worse, CPUHP_BLK_MQ_DEAD is a cpuhp state handled after the CPU is down, so there isn't any chance to quiesce the hctx before shutting down the CPU. Add new CPUHP_AP_BLK_MQ_ONLINE state to stop allocating from blk-mq hctxs where the last CPU goes away, and wait for completion of in-flight requests. This guarantees that there is no inflight I/O before shutting down the managed IRQ. Add a BLK_MQ_F_STACKING and set it for dm-rq and loop, so we don't need to wait for completion of in-flight requests from these drivers to avoid a potential dead-lock. It is safe to do this for stacking drivers as those do not use interrupts at all and their I/O completions are triggered by underlying devices I/O completion. [1] https://lore.kernel.org/linux-block/alpine.DEB.2.21.1904051331270.1802@nanos.tec.linutronix.de/ [hch: different retry mechanism, merged two patches, minor cleanups] Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Daniel Wagner <dwagner@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-05-29blk-mq: add blk_mq_all_tag_iterMing Lei1-18/+32
Add a new blk_mq_all_tag_iter function to iterate over all allocated scheduler tags and driver tags. This is more flexible than the existing blk_mq_all_tag_busy_iter function as it allows the callers to do whatever they want on allocated request instead of being limited to started requests. It will be used to implement draining allocated requests on specified hctx in this patchset. [hch: switch from the two booleans to a more readable flags field and consolidate the tags iter functions] Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Daniel Wagner <dwagner@suse.de> Reviewed-by: Bart van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-05-29blk-mq: use BLK_MQ_NO_TAG in more placesChristoph Hellwig1-4/+4
Replace various magic -1 constants for tags with BLK_MQ_NO_TAG. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Daniel Wagner <dwagner@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-05-29blk-mq: rename BLK_MQ_TAG_FAIL to BLK_MQ_NO_TAGChristoph Hellwig1-2/+2
To prepare for wider use of this constant give it a more applicable name. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Daniel Wagner <dwagner@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-02-26blk-mq: Remove some unused function argumentsJohn Garry1-2/+2
The struct blk_mq_hw_ctx pointer argument in blk_mq_put_tag(), blk_mq_poll_nsecs(), and blk_mq_poll_hybrid_sleep() is unused, so remove it. Overall obj code size shows a minor reduction, before: text data bss dec hex filename 27306 1312 0 28618 6fca block/blk-mq.o 4303 272 0 4575 11df block/blk-mq-tag.o after: 27282 1312 0 28594 6fb2 block/blk-mq.o 4311 272 0 4583 11e7 block/blk-mq-tag.o Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: John Garry <john.garry@huawei.com> -- This minor patch had been carried as part of the blk-mq shared tags RFC, I'd rather not carry it anymore as it required rebasing, so now or never.. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-11-13blk-mq: Delete blk_mq_has_free_tags() and blk_mq_can_queue()John Garry1-8/+0
These functions are not referenced, so delete them. Signed-off-by: John Garry <john.garry@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-08-05blk-mq: introduce blk_mq_tagset_wait_completed_request()Ming Lei1-0/+32
blk-mq may schedule to call queue's complete function on remote CPU via IPI, but doesn't provide any way to synchronize the request's complete fn. The current queue freeze interface can't provide the synchonization because aborted requests stay at blk-mq queues during EH. In some driver's EH(such as NVMe), hardware queue's resource may be freed & re-allocated. If the completed request's complete fn is run finally after the hardware queue's resource is released, kernel crash will be triggered. Prepare for fixing this kind of issue by introducing blk_mq_tagset_wait_completed_request(). Cc: Max Gurtovoy <maxg@mellanox.com> Cc: Sagi Grimberg <sagi@grimberg.me> Cc: Keith Busch <keith.busch@intel.com> Cc: Christoph Hellwig <hch@lst.de> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-07-03blk-mq: remove blk_mq_put_ctx()Bart Van Assche1-8/+0
No code that occurs between blk_mq_get_ctx() and blk_mq_put_ctx() depends on preemption being disabled for its correctness. Since removing the CPU preemption calls does not measurably affect performance, simplify the blk-mq code by removing the blk_mq_put_ctx() function and also by not disabling preemption in blk_mq_get_ctx(). Cc: Hannes Reinecke <hare@suse.com> Cc: Omar Sandoval <osandov@fb.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-05-01block: add SPDX tags to block layer files missing licensing informationChristoph Hellwig1-0/+1
Various block layer files do not have any licensing information at all. Add SPDX tags for the default kernel GPLv2 license to those. Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-02-01blk-mq: save queue mapping result into ctx directlyJianchao Wang1-1/+1
Currently, the queue mapping result is saved in a two-dimensional array. In the hot path, to get a hctx, we need do following: q->queue_hw_ctx[q->tag_set->map[type].mq_map[cpu]] This isn't very efficient. We could save the queue mapping result into ctx directly with different hctx type, like, ctx->hctxs[type] Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-01sbitmap: optimize wakeup checkJens Axboe1-6/+5
Even if we have no waiters on any of the sbitmap_queue wait states, we still have to loop every entry to check. We do this for every IO, so the cost adds up. Shift a bit of the cost to the slow path, when we actually have waiters. Wrap prepare_to_wait_exclusive() and finish_wait(), so we can maintain an internal count of how many are currently active. Then we can simply check this count in sbq_wake_ptr() and not have to loop if we don't have any sleepers. Convert the two users of sbitmap with waiting, blk-mq-tag and iSCSI. Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-08blk-mq-tag: document tag iteration helper return valueJens Axboe1-4/+8
Document the fact that the strategy function passed in can control whether to continue iterating or not. Suggested-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-08blk-mq-tag: change busy_iter_fn to return whether to continue or notJens Axboe1-2/+2
We have this functionality in sbitmap, but we don't export it in blk-mq for users of the tags busy iteration. This can be useful for stopping the iteration, if the caller doesn't need to find more requests. Reviewed-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07blk-mq: cache request hardware queue mappingJens Axboe1-8/+1
We call blk_mq_map_queue() a lot, at least two times for each request per IO, sometimes more. Since we now have an indirect call as well in that function. cache the mapping so we don't have to re-call blk_mq_map_queue() for the same request multiple times. Reviewed-by: Keith Busch <keith.busch@intel.com> Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07blk-mq: pass in request/bio flags to queue mappingJens Axboe1-2/+3
Prep patch for being able to place request based not just on CPU location, but also on the type of request. Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07block: remove legacy rq taggingJens Axboe1-4/+2
It's now unused, kill it. Reviewed-by: Hannes Reinecke <hare@suse.com> Tested-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-10-01Merge tag 'v4.19-rc6' into for-4.20/blockJens Axboe1-5/+2
Merge -rc6 in, for two reasons: 1) Resolve a trivial conflict in the blk-mq-tag.c documentation 2) A few important regression fixes went into upstream directly, so they aren't in the 4.20 branch. Signed-off-by: Jens Axboe <axboe@kernel.dk> * tag 'v4.19-rc6': (780 commits) Linux 4.19-rc6 MAINTAINERS: fix reference to moved drivers/{misc => auxdisplay}/panel.c cpufreq: qcom-kryo: Fix section annotations perf/core: Add sanity check to deal with pinned event failure xen/blkfront: correct purging of persistent grants Revert "xen/blkfront: When purging persistent grants, keep them in the buffer" selftests/powerpc: Fix Makefiles for headers_install change blk-mq: I/O and timer unplugs are inverted in blktrace dax: Fix deadlock in dax_lock_mapping_entry() x86/boot: Fix kexec booting failure in the SEV bit detection code bcache: add separate workqueue for journal_write to avoid deadlock drm/amd/display: Fix Edid emulation for linux drm/amd/display: Fix Vega10 lightup on S3 resume drm/amdgpu: Fix vce work queue was not cancelled when suspend Revert "drm/panel: Add device_link from panel device to DRM device" xen/blkfront: When purging persistent grants, keep them in the buffer clocksource/drivers/timer-atmel-pit: Properly handle error cases block: fix deadline elevator drain for zoned block devices ACPI / hotplug / PCI: Don't scan for non-hotplug bridges if slot is not bridge drm/syncobj: Don't leak fences when WAIT_FOR_SUBMIT is set ... Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-26blk-mq: Allow blocking queue tag iter callbacksKeith Busch1-9/+4
A recent commit runs tag iterator callbacks under the rcu read lock, but existing callbacks do not satisfy the non-blocking requirement. The commit intended to prevent an iterator from accessing a queue that's being modified. This patch fixes the original issue by taking a queue reference instead of reading it, which allows callbacks to make blocking calls. Fixes: f5bbbbe4d6357 ("blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter") Acked-by: Jianchao Wang <jianchao.w.wang@oracle.com> Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-22blk-mq: Document the functions that iterate over requestsBart Van Assche1-7/+64
Make it easier to understand the purpose of the functions that iterate over requests by documenting their purpose. Fix several minor spelling and grammer mistakes in comments in these functions. Signed-off-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Ming Lei <ming.lei@redhat.com> Cc: Jianchao Wang <jianchao.w.wang@oracle.com> Cc: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-22Merge tag 'for-4.19/post-20180822' of git://git.kernel.dk/linux-blockLinus Torvalds1-1/+13
Pull more block updates from Jens Axboe: - Set of bcache fixes and changes (Coly) - The flush warn fix (me) - Small series of BFQ fixes (Paolo) - wbt hang fix (Ming) - blktrace fix (Steven) - blk-mq hardware queue count update fix (Jianchao) - Various little fixes * tag 'for-4.19/post-20180822' of git://git.kernel.dk/linux-block: (31 commits) block/DAC960.c: make some arrays static const, shrinks object size blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter blk-mq: init hctx sched after update ctx and hctx mapping block: remove duplicate initialization tracing/blktrace: Fix to allow setting same value pktcdvd: fix setting of 'ret' error return for a few cases block: change return type to bool block, bfq: return nbytes and not zero from struct cftype .write() method block, bfq: improve code of bfq_bfqq_charge_time block, bfq: reduce write overcharge block, bfq: always update the budget of an entity when needed block, bfq: readd missing reset of parent-entity service blk-wbt: fix IO hang in wbt_wait() block: don't warn for flush on read-only device bcache: add the missing comments for smp_mb()/smp_wmb() bcache: remove unnecessary space before ioctl function pointer arguments bcache: add missing SPDX header bcache: move open brace at end of function definitions to next line bcache: add static const prefix to char * array declarations bcache: fix code comments style ...
2018-08-21blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iterJianchao Wang1-1/+13
For blk-mq, part_in_flight/rw will invoke blk_mq_in_flight/rw to account the inflight requests. It will access the queue_hw_ctx and nr_hw_queues w/o any protection. When updating nr_hw_queues and blk_mq_in_flight/rw occur concurrently, panic comes up. Before update nr_hw_queues, the q will be frozen. So we could use q_usage_counter to avoid the race. percpu_ref_is_zero is used here so that we will not miss any in-flight request. The access to nr_hw_queues and queue_hw_ctx in blk_mq_queue_tag_busy_iter are under rcu critical section, __blk_mq_update_nr_hw_queues could use synchronize_rcu to ensure the zeroed q_usage_counter to be globally visible. Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-14Merge tag 'for-4.19/block-20180812' of git://git.kernel.dk/linux-blockLinus Torvalds1-4/+7
Pull block updates from Jens Axboe: "First pull request for this merge window, there will also be a followup request with some stragglers. This pull request contains: - Fix for a thundering heard issue in the wbt block code (Anchal Agarwal) - A few NVMe pull requests: * Improved tracepoints (Keith) * Larger inline data support for RDMA (Steve Wise) * RDMA setup/teardown fixes (Sagi) * Effects log suppor for NVMe target (Chaitanya Kulkarni) * Buffered IO suppor for NVMe target (Chaitanya Kulkarni) * TP4004 (ANA) support (Christoph) * Various NVMe fixes - Block io-latency controller support. Much needed support for properly containing block devices. (Josef) - Series improving how we handle sense information on the stack (Kees) - Lightnvm fixes and updates/improvements (Mathias/Javier et al) - Zoned device support for null_blk (Matias) - AIX partition fixes (Mauricio Faria de Oliveira) - DIF checksum code made generic (Max Gurtovoy) - Add support for discard in iostats (Michael Callahan / Tejun) - Set of updates for BFQ (Paolo) - Removal of async write support for bsg (Christoph) - Bio page dirtying and clone fixups (Christoph) - Set of bcache fix/changes (via Coly) - Series improving blk-mq queue setup/teardown speed (Ming) - Series improving merging performance on blk-mq (Ming) - Lots of other fixes and cleanups from a slew of folks" * tag 'for-4.19/block-20180812' of git://git.kernel.dk/linux-block: (190 commits) blkcg: Make blkg_root_lookup() work for queues in bypass mode bcache: fix error setting writeback_rate through sysfs interface null_blk: add lock drop/acquire annotation Blk-throttle: reduce tail io latency when iops limit is enforced block: paride: pd: mark expected switch fall-throughs block: Ensure that a request queue is dissociated from the cgroup controller block: Introduce blk_exit_queue() blkcg: Introduce blkg_root_lookup() block: Remove two superfluous #include directives blk-mq: count the hctx as active before allocating tag block: bvec_nr_vecs() returns value for wrong slab bcache: trivial - remove tailing backslash in macro BTREE_FLAG bcache: make the pr_err statement used for ENOENT only in sysfs_attatch section bcache: set max writeback rate when I/O request is idle bcache: add code comments for bset.c bcache: fix mistaken comments in request.c bcache: fix mistaken code comments in bcache.h bcache: add a comment in super.c bcache: avoid unncessary cache prefetch bch_btree_node_get() bcache: display rate debug parameters to 0 when writeback is not running ...
2018-08-09blk-mq: count the hctx as active before allocating tagJianchao Wang1-0/+3
Currently, we count the hctx as active after allocate driver tag successfully. If a previously inactive hctx try to get tag first time, it may fails and need to wait. However, due to the stale tag ->active_queues, the other shared-tags users are still able to occupy all driver tags while there is someone waiting for tag. Consequently, even if the previously inactive hctx is waked up, it still may not be able to get a tag and could be starved. To fix it, we count the hctx as active before try to allocate driver tag, then when it is waiting the tag, the other shared-tag users will reserve budget for it. Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jianchao Wang <jianchao.w.wang@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-02blk-mq: fix blk_mq_tagset_busy_iterMing Lei1-1/+1
Commit d250bf4e776ff09d5("blk-mq: only iterate over inflight requests in blk_mq_tagset_busy_iter") uses 'blk_mq_rq_state(rq) == MQ_RQ_IN_FLIGHT' to replace 'blk_mq_request_started(req)', this way is wrong, and causes lots of test system hang during booting. Fix the issue by using blk_mq_request_started(req) inside bt_tags_iter(). Fixes: d250bf4e776ff09d5 ("blk-mq: only iterate over inflight requests in blk_mq_tagset_busy_iter") Cc: Josef Bacik <josef@toxicpanda.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Mark Brown <broonie@kernel.org> Cc: Matt Hart <matthew.hart@linaro.org> Cc: Johannes Thumshirn <jthumshirn@suse.de> Cc: John Garry <john.garry@huawei.com> Cc: Hannes Reinecke <hare@suse.com>, Cc: "Martin K. Petersen" <martin.petersen@oracle.com>, Cc: James Bottomley <James.Bottomley@hansenpartnership.com> Cc: linux-scsi@vger.kernel.org Cc: linux-kernel@vger.kernel.org Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com> Tested-by: Guenter Roeck <linux@roeck-us.net> Reported-by: Mark Brown <broonie@kernel.org> Reported-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-02blk-mq: fix updating tags depthMing Lei1-4/+4
The passed 'nr' from userspace represents the total depth, meantime inside 'struct blk_mq_tags', 'nr_tags' stores the total tag depth, and 'nr_reserved_tags' stores the reserved part. There are two issues in blk_mq_tag_update_depth() now: 1) for growing tags, we should have used the passed 'nr', and keep the number of reserved tags not changed. 2) the passed 'nr' should have been used for checking against 'tags->nr_tags', instead of number of the normal part. This patch fixes the above two cases, and avoids kernel crash caused by wrong resizing sbitmap queue. Cc: "Ewan D. Milne" <emilne@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Bart Van Assche <bart.vanassche@sandisk.com> Cc: Omar Sandoval <osandov@fb.com> Tested by: Marco Patalano <mpatalan@redhat.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-06-14blk-mq: remove blk_mq_tagset_iterChristoph Hellwig1-29/+0
Unused now that nvme stopped using it. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jens Axboe <axboe@kernel.dk>
2018-05-30blk-mq: only iterate over inflight requests in blk_mq_tagset_busy_iterChristoph Hellwig1-1/+1
We already check for started commands in all callbacks, but we should also protect against already completed commands. Do this by taking the checks to common code. Acked-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-24blk-mq: avoid starving tag allocation after allocating process migratesMing Lei1-0/+12
When the allocation process is scheduled back and the mapped hw queue is changed, fake one extra wake up on previous queue for compensating wake up miss, so other allocations on the previous queue won't be starved. This patch fixes one request allocation hang issue, which can be triggered easily in case of very low nr_request. The race is as follows: 1) 2 hw queues, nr_requests are 2, and wake_batch is one 2) there are 3 waiters on hw queue 0 3) two in-flight requests in hw queue 0 are completed, and only two waiters of 3 are waken up because of wake_batch, but both the two waiters can be scheduled to another CPU and cause to switch to hw queue 1 4) then the 3rd waiter will wait for ever, since no in-flight request is in hw queue 0 any more. 5) this patch fixes it by the fake wakeup when waiter is scheduled to another hw queue Cc: <stable@vger.kernel.org> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Modified commit message to make it clearer, and make it apply on top of the 4.18 branch. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-12-22blk-mq: improve heavily contended tag caseJens Axboe1-6/+7
Even with a number of waitqueues, we can get into a situation where we are heavily contended on the waitqueue lock. I got a report on spc1 where we're spending seconds doing this. Arguably the use case is nasty, I reproduce it with one device and 1000 threads banging on the device. But that doesn't mean we shouldn't be handling it better. What ends up happening is that a thread will fail to get a tag, add itself to the waitqueue, and subsequently get woken up when a tag is freed - only to find itself going back to sleep on the waitqueue. Instead of waking all threads, use an exclusive wait and wake up our sbitmap batch count instead. This seems to work well for me (massive improvement for this use case), and it survives basic testing. But I haven't fully verified it yet. An additional improvement is running the queue and checking for a new tag BEFORE needing to add ourselves to the waitqueue. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-10-18block: remove blk_mq_reinit_tagsetSagi Grimberg1-7/+0
No callers left. Reviewed-by: Jens Axboe <axboe@kernel.dk> Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com> Reviewed-by: Max Gurtovoy <maxg@mellanox.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Christoph Hellwig <hch@lst.de>
2017-10-18block: introduce blk_mq_tagset_iterSagi Grimberg1-5/+11
Iterator helper to apply a function on all the tags in a given tagset. export it as it will be used outside the block layer later on. Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com> Reviewed-by: Jens Axboe <axboe@kernel.dk> Reviewed-by: Max Gurtovoy <maxg@mellanox.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Christoph Hellwig <hch@lst.de>
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