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2022-09-27blk-mq: use quiesced elevator switch when reinitializing queuesKeith Busch1-2/+2
The hctx's run_work may be racing with the elevator switch when reinitializing hardware queues. The queue is merely frozen in this context, but that only prevents requests from allocating and doesn't stop the hctx work from running. The work may get an elevator pointer that's being torn down, and can result in use-after-free errors and kernel panics (example below). Use the quiesced elevator switch instead, and make the previous one static since it is now only used locally. nvme nvme0: resetting controller nvme nvme0: 32/0/0 default/read/poll queues BUG: kernel NULL pointer dereference, address: 0000000000000008 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 80000020c8861067 P4D 80000020c8861067 PUD 250f8c8067 PMD 0 Oops: 0000 [#1] SMP PTI Workqueue: kblockd blk_mq_run_work_fn RIP: 0010:kyber_has_work+0x29/0x70 ... Call Trace: __blk_mq_do_dispatch_sched+0x83/0x2b0 __blk_mq_sched_dispatch_requests+0x12e/0x170 blk_mq_sched_dispatch_requests+0x30/0x60 __blk_mq_run_hw_queue+0x2b/0x50 process_one_work+0x1ef/0x380 worker_thread+0x2d/0x3e0 Signed-off-by: Keith Busch <kbusch@kernel.org> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220927155652.3260724-1-kbusch@fb.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-03-21Merge tag 'for-5.18/block-2022-03-18' of git://git.kernel.dk/linux-blockLinus Torvalds1-8/+8
Pull block updates from Jens Axboe: - BFQ cleanups and fixes (Yu, Zhang, Yahu, Paolo) - blk-rq-qos completion fix (Tejun) - blk-cgroup merge fix (Tejun) - Add offline error return value to distinguish it from an IO error on the device (Song) - IO stats fixes (Zhang, Christoph) - blkcg refcount fixes (Ming, Yu) - Fix for indefinite dispatch loop softlockup (Shin'ichiro) - blk-mq hardware queue management improvements (Ming) - sbitmap dead code removal (Ming, John) - Plugging merge improvements (me) - Show blk-crypto capabilities in sysfs (Eric) - Multiple delayed queue run improvement (David) - Block throttling fixes (Ming) - Start deprecating auto module loading based on dev_t (Christoph) - bio allocation improvements (Christoph, Chaitanya) - Get rid of bio_devname (Christoph) - bio clone improvements (Christoph) - Block plugging improvements (Christoph) - Get rid of genhd.h header (Christoph) - Ensure drivers use appropriate flush helpers (Christoph) - Refcounting improvements (Christoph) - Queue initialization and teardown improvements (Ming, Christoph) - Misc fixes/improvements (Barry, Chaitanya, Colin, Dan, Jiapeng, Lukas, Nian, Yang, Eric, Chengming) * tag 'for-5.18/block-2022-03-18' of git://git.kernel.dk/linux-block: (127 commits) block: cancel all throttled bios in del_gendisk() block: let blkcg_gq grab request queue's refcnt block: avoid use-after-free on throttle data block: limit request dispatch loop duration block/bfq-iosched: Fix spelling mistake "tenative" -> "tentative" sr: simplify the local variable initialization in sr_block_open() block: don't merge across cgroup boundaries if blkcg is enabled block: fix rq-qos breakage from skipping rq_qos_done_bio() block: flush plug based on hardware and software queue order block: ensure plug merging checks the correct queue at least once block: move rq_qos_exit() into disk_release() block: do more work in elevator_exit block: move blk_exit_queue into disk_release block: move q_usage_counter release into blk_queue_release block: don't remove hctx debugfs dir from blk_mq_exit_queue block: move blkcg initialization/destroy into disk allocation/release handler sr: implement ->free_disk to simplify refcounting sd: implement ->free_disk to simplify refcounting sd: delay calling free_opal_dev sd: call sd_zbc_release_disk before releasing the scsi_device reference ...
2022-03-08block: do more work in elevator_exitChristoph Hellwig1-3/+3
Move the calls to ioc_clear_queue and blk_mq_sched_free_rqs into elevator_exit. Except for one call where we know we can't have io_cq structures yet these always go together, and that extra call in an error path is harmless. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220308055200.735835-14-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-02-28block: simplify calling convention of elv_unregister_queue()Eric Biggers1-4/+4
Make elv_unregister_queue() a no-op if q->elevator is NULL or is not registered. This simplifies the existing callers, as well as the future caller in the error path of blk_register_queue(). Also don't bother checking whether q is NULL, since it never is. Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Eric Biggers <ebiggers@google.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220124215938.2769-2-ebiggers@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-02-17block/wbt: fix negative inflight counter when remove scsi deviceLaibin Qiu1-2/+0
Now that we disable wbt by set WBT_STATE_OFF_DEFAULT in wbt_disable_default() when switch elevator to bfq. And when we remove scsi device, wbt will be enabled by wbt_enable_default. If it become false positive between wbt_wait() and wbt_track() when submit write request. The following is the scenario that triggered the problem. T1 T2 T3 elevator_switch_mq bfq_init_queue wbt_disable_default <= Set rwb->enable_state (OFF) Submit_bio blk_mq_make_request rq_qos_throttle <= rwb->enable_state (OFF) scsi_remove_device sd_remove del_gendisk blk_unregister_queue elv_unregister_queue wbt_enable_default <= Set rwb->enable_state (ON) q_qos_track <= rwb->enable_state (ON) ^^^^^^ this request will mark WBT_TRACKED without inflight add and will lead to drop rqw->inflight to -1 in wbt_done() which will trigger IO hung. Fix this by move wbt_enable_default() from elv_unregister to bfq_exit_queue(). Only re-enable wbt when bfq exit. Fixes: 76a8040817b4b ("blk-wbt: make sure throttle is enabled properly") Remove oneline stale comment, and kill one oneshot local variable. Signed-off-by: Ming Lei <ming.lei@rehdat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/linux-block/20211214133103.551813-1-qiulaibin@huawei.com/ Signed-off-by: Laibin Qiu <qiulaibin@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-02-11block: partition include/linux/blk-cgroup.hMing Lei1-1/+1
Partition include/linux/blk-cgroup.h into two parts: one is public part, the other is block layer private part. Suggested by Christoph Hellwig. Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20220211101149.2368042-4-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29block: remove the e argument to elevator_exitChristoph Hellwig1-3/+5
All callers pass q->elevator. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20211123185312.1432157-4-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-29block: remove elevator_exitChristoph Hellwig1-1/+3
Open code elevator_exit in it's only caller, and rename __elevator_exit to elevator_exit. Signed-off-by: Christoph Hellwig <hch@lst.de> Link: https://lore.kernel.org/r/20211123185312.1432157-3-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-11-17block: avoid to quiesce queue in elevator_init_mqMing Lei1-2/+8
elevator_init_mq() is only called before adding disk, when there isn't any FS I/O, only passthrough requests can be queued, so freezing queue plus canceling dispatch work is enough to drain any dispatch activities, then we can avoid synchronize_srcu() in blk_mq_quiesce_queue(). Long boot latency issue can be fixed in case of lots of disks added during booting. Fixes: 737eb78e82d5 ("block: Delay default elevator initialization") Reported-by: yangerkun <yangerkun@huawei.com> Cc: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20211117115502.1600950-1-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-10-18blk-mq: Change shared sbitmap naming to shared tagsJohn Garry1-1/+1
Now that shared sbitmap support really means shared tags, rename symbols to match that. Signed-off-by: John Garry <john.garry@huawei.com> Link: https://lore.kernel.org/r/1633429419-228500-15-git-send-email-john.garry@huawei.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-10-18block: move elevator.h to block/Christoph Hellwig1-1/+1
Except for the features passed to blk_queue_required_elevator_features, elevator.h is only needed internally to the block layer. Move the ELEVATOR_F_* definitions to blkdev.h, and the move elevator.h to block/, dropping all the spurious includes outside of that. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Link: https://lore.kernel.org/r/20210920123328.1399408-13-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-09block: return ELEVATOR_DISCARD_MERGE if possibleMing Lei1-0/+3
When merging one bio to request, if they are discard IO and the queue supports multi-range discard, we need to return ELEVATOR_DISCARD_MERGE because both block core and related drivers(nvme, virtio-blk) doesn't handle mixed discard io merge(traditional IO merge together with discard merge) well. Fix the issue by returning ELEVATOR_DISCARD_MERGE in this situation, so both blk-mq and drivers just need to handle multi-range discard. Reported-by: Oleksandr Natalenko <oleksandr@natalenko.name> Signed-off-by: Ming Lei <ming.lei@redhat.com> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Fixes: 2705dfb20947 ("block: fix discard request merge") Link: https://lore.kernel.org/r/20210729034226.1591070-1-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-09block: remove support for delayed queue registrationsChristoph Hellwig1-1/+0
Now that device mapper has been changed to register the disk once it is fully ready all this code is unused. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Mike Snitzer <snitzer@redhat.com> Link: https://lore.kernel.org/r/20210804094147.459763-9-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-05blk-mq: Introduce the BLK_MQ_F_NO_SCHED_BY_DEFAULT flagBart Van Assche1-0/+3
elevator_get_default() uses the following algorithm to select an I/O scheduler from inside add_disk(): - In case of a single hardware queue or if sharing hardware queues across multiple request queues (BLK_MQ_F_TAG_HCTX_SHARED), use mq-deadline. - Otherwise, use 'none'. This is a good choice for most but not for all block drivers. Make it possible to override the selection of mq-deadline with a new flag, namely BLK_MQ_F_NO_SCHED_BY_DEFAULT. Cc: Christoph Hellwig <hch@lst.de> Cc: Ming Lei <ming.lei@redhat.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Martijn Coenen <maco@android.com> Cc: Jaegeuk Kim <jaegeuk@kernel.org> Signed-off-by: Bart Van Assche <bvanassche@acm.org> Link: https://lore.kernel.org/r/20210805174200.3250718-2-bvanassche@acm.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-24blk: Fix lock inversion between ioc lock and bfqd lockJan Kara1-3/+8
Lockdep complains about lock inversion between ioc->lock and bfqd->lock: bfqd -> ioc: put_io_context+0x33/0x90 -> ioc->lock grabbed blk_mq_free_request+0x51/0x140 blk_put_request+0xe/0x10 blk_attempt_req_merge+0x1d/0x30 elv_attempt_insert_merge+0x56/0xa0 blk_mq_sched_try_insert_merge+0x4b/0x60 bfq_insert_requests+0x9e/0x18c0 -> bfqd->lock grabbed blk_mq_sched_insert_requests+0xd6/0x2b0 blk_mq_flush_plug_list+0x154/0x280 blk_finish_plug+0x40/0x60 ext4_writepages+0x696/0x1320 do_writepages+0x1c/0x80 __filemap_fdatawrite_range+0xd7/0x120 sync_file_range+0xac/0xf0 ioc->bfqd: bfq_exit_icq+0xa3/0xe0 -> bfqd->lock grabbed put_io_context_active+0x78/0xb0 -> ioc->lock grabbed exit_io_context+0x48/0x50 do_exit+0x7e9/0xdd0 do_group_exit+0x54/0xc0 To avoid this inversion we change blk_mq_sched_try_insert_merge() to not free the merged request but rather leave that upto the caller similarly to blk_mq_sched_try_merge(). And in bfq_insert_requests() we make sure to free all the merged requests after dropping bfqd->lock. Fixes: aee69d78dec0 ("block, bfq: introduce the BFQ-v0 I/O scheduler as an extra scheduler") Reviewed-by: Ming Lei <ming.lei@redhat.com> Acked-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20210623093634.27879-3-jack@suse.cz Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-18block: Remove unnecessary elevator operation checksDamien Le Moal1-0/+4
The insert_requests and dispatch_request elevator operations are mandatory for the correct execution of an elevator, and all implemented elevators (bfq, kyber and mq-deadline) implement them. As a result, there is no need to check for these operations before calling them when a queue has an elevator set. This simplifies the code in __blk_mq_sched_dispatch_requests() and blk_mq_sched_insert_request(). To avoid out-of-tree elevators to crash the kernel in case of bad implementation, add a check in elv_register() to verify that these operations are implemented. A small, probably not significant, IOPS improvement of 0.1% is observed with this patch applied (4.117 MIOPS to 4.123 MIOPS, average of 20 fio runs doing 4K random direct reads with psync and 32 jobs). Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Link: https://lore.kernel.org/r/20210618015922.713999-1-damien.lemoal@wdc.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-11blk-mq: improve the blk_mq_init_allocated_queue interfaceChristoph Hellwig1-1/+1
Don't return the passed in request_queue but a normal error code, and drop the elevator_init argument in favor of just calling elevator_init_mq directly from dm-rq. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Link: https://lore.kernel.org/r/20210602065345.355274-3-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-04-07blk-mq: set default elevator as deadline in case of hctx shared tagsetMing Lei1-1/+2
Yanhui found that write performance is degraded a lot after applying hctx shared tagset on one test machine with megaraid_sas. And turns out it is caused by none scheduler which becomes default elevator caused by hctx shared tagset patchset. Given more scsi HBAs will apply hctx shared tagset, and the similar performance exists for them too. So keep previous behavior by still using default mq-deadline for queues which apply hctx shared tagset, just like before. Fixes: 32bc15afed04 ("blk-mq: Facilitate a shared sbitmap per tagset") Reported-by: Yanhui Ma <yama@redhat.com> Cc: John Garry <john.garry@huawei.com> Cc: Hannes Reinecke <hare@suse.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: John Garry <john.garry@huawei.com> Link: https://lore.kernel.org/r/20210406031933.767228-1-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-10-09block: fix comment and add lockdep assertYufen Yu1-10/+4
After commit b89f625e28d4 ("block: don't release queue's sysfs lock during switching elevator"), whole elevator register and unregister function are covered by sysfs_lock. So, remove wrong comment and add lockdep assert. Signed-off-by: Yufen Yu <yuyufen@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-10-09block: use helper function to test queue registerYufen Yu1-1/+1
We have defined common interface blk_queue_registered() to test QUEUE_FLAG_REGISTERED. Just use it. Signed-off-by: Yufen Yu <yuyufen@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-10-09block: remove redundant mq checkYufen Yu1-2/+2
elv_support_iosched() will check queue_is_mq() for us. So, remove the redundant check to clean code. Signed-off-by: Yufen Yu <yuyufen@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-10-09block: invoke blk_mq_exit_sched no matter whether have .exit_schedYufen Yu1-2/+1
We will register debugfs for scheduler no matter whether it have defined callback funciton .exit_sched. So, blk_mq_exit_sched() is always needed to unregister debugfs. Also, q->elevator should be set as NULL after exiting scheduler. For now, since all register scheduler have defined .exit_sched, it will not cause any actual problem. But It will be more reasonable to do this change. Signed-off-by: Yufen Yu <yuyufen@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-07-31block: elevator: delete duplicated word and fix typosRandy Dunlap1-2/+2
Drop the repeated word "the". Fix typos of "features" and "specified". Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: linux-block@vger.kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-11-07Merge branch 'for-linus' into for-5.5/blockJens Axboe1-1/+2
Pull on for-linus to resolve what otherwise would have been a conflict with the cgroups rstat patchset from Tejun. * for-linus: (942 commits) blkcg: make blkcg_print_stat() print stats only for online blkgs nvme: change nvme_passthru_cmd64 to explicitly mark rsvd nvme-multipath: fix crash in nvme_mpath_clear_ctrl_paths nvme-rdma: fix a segmentation fault during module unload iocost: don't nest spin_lock_irq in ioc_weight_write() io_uring: ensure we clear io_kiocb->result before each issue um-ubd: Entrust re-queue to the upper layers nvme-multipath: remove unused groups_only mode in ana log nvme-multipath: fix possible io hang after ctrl reconnect io_uring: don't touch ctx in setup after ring fd install io_uring: Fix leaked shadow_req Linux 5.4-rc5 riscv: cleanup do_trap_break nbd: verify socket is supported during setup ata: libahci_platform: Fix regulator_get_optional() misuse nbd: handle racing with error'ed out commands nbd: protect cmd->status with cmd->lock io_uring: fix bad inflight accounting for SETUP_IOPOLL|SETUP_SQTHREAD io_uring: used cached copies of sq->dropped and cq->overflow ARM: dts: stm32: relax qspi pins slew-rate for stm32mp157 ...
2019-11-06block: Warn if elevator= parameter is usedJan Kara1-0/+9
With transition to blk-mq, the elevator= kernel argument was removed as it makes less and less sense with the current variety of devices. Since this may surprise some users and there are advices on the Internet that still suggest to use it, let's at least warn if the parameter is used. Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-14block: Fix elv_support_iosched()Damien Le Moal1-1/+2
A BIO based request queue does not have a tag_set, which prevent testing for the flag BLK_MQ_F_NO_SCHED indicating that the queue does not require an elevator. This leads to an incorrect initialization of a default elevator in some cases such as BIO based null_blk (queue_mode == BIO) with zoned mode enabled as the default elevator in this case is mq-deadline instead of "none". Fix this by testing for a NULL queue mq_ops field which indicates that the queue is BIO based and should not have an elevator. Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com> Reviewed-by: Bob Liu <bob.liu@oracle.com> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-26block: don't release queue's sysfs lock during switching elevatorMing Lei1-30/+1
cecf5d87ff20 ("block: split .sysfs_lock into two locks") starts to release & acquire sysfs_lock before registering/un-registering elevator queue during switching elevator for avoiding potential deadlock from showing & storing 'queue/iosched' attributes and removing elevator's kobject. Turns out there isn't such deadlock because 'q->sysfs_lock' isn't required in .show & .store of queue/iosched's attributes, and just elevator's sysfs lock is acquired in elv_iosched_store() and elv_iosched_show(). So it is safe to hold queue's sysfs lock when registering/un-registering elevator queue. The biggest issue is that commit cecf5d87ff20 assumes that concurrent write on 'queue/scheduler' can't happen. However, this assumption isn't true, because kernfs_fop_write() only guarantees that concurrent write aren't called on the same open file, but the write could be from different open on the file. So we can't release & re-acquire queue's sysfs lock during switching elevator, otherwise use-after-free on elevator could be triggered. Fixes the issue by not releasing queue's sysfs lock during switching elevator. Fixes: cecf5d87ff20 ("block: split .sysfs_lock into two locks") Cc: Christoph Hellwig <hch@infradead.org> Cc: Hannes Reinecke <hare@suse.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Mike Snitzer <snitzer@redhat.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-06block: fix elevator_get_by_features()Jens Axboe1-6/+7
The lookup logic is broken - 'e' will never be NULL, even if the list is empty. Maintain lookup hit in a separate variable instead. Fixes: a0958ba7fcdc ("block: Improve default elevator selection") Reported-by: Julia Lawall <julia.lawall@lip6.fr> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-05block: Delay default elevator initializationDamien Le Moal1-0/+7
When elevator_init_mq() is called from blk_mq_init_allocated_queue(), the only information known about the device is the number of hardware queues as the block device scan by the device driver is not completed yet for most drivers. The device type and elevator required features are not set yet, preventing to correctly select the default elevator most suitable for the device. This currently affects all multi-queue zoned block devices which default to the "none" elevator instead of the required "mq-deadline" elevator. These drives currently include host-managed SMR disks connected to a smartpqi HBA and null_blk block devices with zoned mode enabled. Upcoming NVMe Zoned Namespace devices will also be affected. Fix this by adding the boolean elevator_init argument to blk_mq_init_allocated_queue() to control the execution of elevator_init_mq(). Two cases exist: 1) elevator_init = false is used for calls to blk_mq_init_allocated_queue() within blk_mq_init_queue(). In this case, a call to elevator_init_mq() is added to __device_add_disk(), resulting in the delayed initialization of the queue elevator after the device driver finished probing the device information. This effectively allows elevator_init_mq() access to more information about the device. 2) elevator_init = true preserves the current behavior of initializing the elevator directly from blk_mq_init_allocated_queue(). This case is used for the special request based DM devices where the device gendisk is created before the queue initialization and device information (e.g. queue limits) is already known when the queue initialization is executed. Additionally, to make sure that the elevator initialization is never done while requests are in-flight (there should be none when the device driver calls device_add_disk()), freeze and quiesce the device request queue before calling blk_mq_init_sched() in elevator_init_mq(). Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-05block: Improve default elevator selectionDamien Le Moal1-7/+44
For block devices that do not specify required features, preserve the current default elevator selection (mq-deadline for single queue devices, none for multi-queue devices). However, for devices specifying required features (e.g. zoned block devices ELEVATOR_F_ZBD_SEQ_WRITE feature), select the first available elevator providing the required features. In all cases, default to "none" if no elevator is available or if the initialization of the default elevator fails. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-05block: Introduce elevator featuresDamien Le Moal1-11/+38
Introduce the definition of elevator features through the elevator_features flags in the elevator_type structure. Each flag can represent a feature supported by an elevator. The first feature defined by this patch is support for zoned block device sequential write constraint with the flag ELEVATOR_F_ZBD_SEQ_WRITE, which is implemented by the mq-deadline elevator using zone write locking. Other possible features are IO priorities, write hints, latency targets or single-LUN dual-actuator disks (for which the elevator could maintain one LBA ordered list per actuator). The required_elevator_features field is also added to the request_queue structure to allow a device driver to specify elevator feature flags that an elevator must support for the correct operation of the device (e.g. device drivers for zoned block devices can have the ELEVATOR_F_ZBD_SEQ_WRITE flag as a required feature). The helper function blk_queue_required_elevator_features() is defined for setting this new field. With these two new fields in place, the elevator functions elevator_match() and elevator_find() are modified to allow a user to set only an elevator with a set of features that satisfies the device required features. Elevators not matching the device requirements are not shown in the device sysfs queue/scheduler file to prevent their use. The "none" elevator can always be selected as before. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-05block: Change elevator_init_mq() to always succeedDamien Le Moal1-11/+12
If the default elevator chosen is mq-deadline, elevator_init_mq() may return an error if mq-deadline initialization fails, leading to blk_mq_init_allocated_queue() returning an error, which in turn will cause the block device initialization to fail and the device not being exposed. Instead of taking such extreme measure, handle mq-deadline initialization failures in the same manner as when mq-deadline is not available (no module to load), that is, default to the "none" scheduler. With this change, elevator_init_mq() return type can be changed to void. Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-05block: Cleanup elevator_init_mq() useDamien Le Moal1-10/+13
Instead of checking a queue tag_set BLK_MQ_F_NO_SCHED flag before calling elevator_init_mq() to make sure that the queue supports IO scheduling, use the elevator.c function elv_support_iosched() in elevator_init_mq(). This does not introduce any functional change but ensure that elevator_init_mq() does the right thing based on the queue settings. Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-03block: elevator.c: Remove now unused elevator= argumentMarcos Paulo de Souza1-14/+0
Since the inclusion of blk-mq, elevator argument was not being considered anymore, and it's utility died long with the legacy IO path, now removed too. Reviewed-by: Hannes Reinecke <hare@suse.com> Reviewed-by: Bob Liu <bob.liu@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Marcos Paulo de Souza <marcos.souza.org@gmail.com> Fold with doc removal patch. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-08-27block: split .sysfs_lock into two locksMing Lei1-8/+47
The kernfs built-in lock of 'kn->count' is held in sysfs .show/.store path. Meantime, inside block's .show/.store callback, q->sysfs_lock is required. However, when mq & iosched kobjects are removed via blk_mq_unregister_dev() & elv_unregister_queue(), q->sysfs_lock is held too. This way causes AB-BA lock because the kernfs built-in lock of 'kn-count' is required inside kobject_del() too, see the lockdep warning[1]. On the other hand, it isn't necessary to acquire q->sysfs_lock for both blk_mq_unregister_dev() & elv_unregister_queue() because clearing REGISTERED flag prevents storing to 'queue/scheduler' from being happened. Also sysfs write(store) is exclusive, so no necessary to hold the lock for elv_unregister_queue() when it is called in switching elevator path. So split .sysfs_lock into two: one is still named as .sysfs_lock for covering sync .store, the other one is named as .sysfs_dir_lock for covering kobjects and related status change. sysfs itself can handle the race between add/remove kobjects and showing/storing attributes under kobjects. For switching scheduler via storing to 'queue/scheduler', we use the queue flag of QUEUE_FLAG_REGISTERED with .sysfs_lock for avoiding the race, then we can avoid to hold .sysfs_lock during removing/adding kobjects. [1] lockdep warning ====================================================== WARNING: possible circular locking dependency detected 5.3.0-rc3-00044-g73277fc75ea0 #1380 Not tainted ------------------------------------------------------ rmmod/777 is trying to acquire lock: 00000000ac50e981 (kn->count#202){++++}, at: kernfs_remove_by_name_ns+0x59/0x72 but task is already holding lock: 00000000fb16ae21 (&q->sysfs_lock){+.+.}, at: blk_unregister_queue+0x78/0x10b which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&q->sysfs_lock){+.+.}: __lock_acquire+0x95f/0xa2f lock_acquire+0x1b4/0x1e8 __mutex_lock+0x14a/0xa9b blk_mq_hw_sysfs_show+0x63/0xb6 sysfs_kf_seq_show+0x11f/0x196 seq_read+0x2cd/0x5f2 vfs_read+0xc7/0x18c ksys_read+0xc4/0x13e do_syscall_64+0xa7/0x295 entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #0 (kn->count#202){++++}: check_prev_add+0x5d2/0xc45 validate_chain+0xed3/0xf94 __lock_acquire+0x95f/0xa2f lock_acquire+0x1b4/0x1e8 __kernfs_remove+0x237/0x40b kernfs_remove_by_name_ns+0x59/0x72 remove_files+0x61/0x96 sysfs_remove_group+0x81/0xa4 sysfs_remove_groups+0x3b/0x44 kobject_del+0x44/0x94 blk_mq_unregister_dev+0x83/0xdd blk_unregister_queue+0xa0/0x10b del_gendisk+0x259/0x3fa null_del_dev+0x8b/0x1c3 [null_blk] null_exit+0x5c/0x95 [null_blk] __se_sys_delete_module+0x204/0x337 do_syscall_64+0xa7/0x295 entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->sysfs_lock); lock(kn->count#202); lock(&q->sysfs_lock); lock(kn->count#202); *** DEADLOCK *** 2 locks held by rmmod/777: #0: 00000000e69bd9de (&lock){+.+.}, at: null_exit+0x2e/0x95 [null_blk] #1: 00000000fb16ae21 (&q->sysfs_lock){+.+.}, at: blk_unregister_queue+0x78/0x10b stack backtrace: CPU: 0 PID: 777 Comm: rmmod Not tainted 5.3.0-rc3-00044-g73277fc75ea0 #1380 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS ?-20180724_192412-buildhw-07.phx4 Call Trace: dump_stack+0x9a/0xe6 check_noncircular+0x207/0x251 ? print_circular_bug+0x32a/0x32a ? find_usage_backwards+0x84/0xb0 check_prev_add+0x5d2/0xc45 validate_chain+0xed3/0xf94 ? check_prev_add+0xc45/0xc45 ? mark_lock+0x11b/0x804 ? check_usage_forwards+0x1ca/0x1ca __lock_acquire+0x95f/0xa2f lock_acquire+0x1b4/0x1e8 ? kernfs_remove_by_name_ns+0x59/0x72 __kernfs_remove+0x237/0x40b ? kernfs_remove_by_name_ns+0x59/0x72 ? kernfs_next_descendant_post+0x7d/0x7d ? strlen+0x10/0x23 ? strcmp+0x22/0x44 kernfs_remove_by_name_ns+0x59/0x72 remove_files+0x61/0x96 sysfs_remove_group+0x81/0xa4 sysfs_remove_groups+0x3b/0x44 kobject_del+0x44/0x94 blk_mq_unregister_dev+0x83/0xdd blk_unregister_queue+0xa0/0x10b del_gendisk+0x259/0x3fa ? disk_events_poll_msecs_store+0x12b/0x12b ? check_flags+0x1ea/0x204 ? mark_held_locks+0x1f/0x7a null_del_dev+0x8b/0x1c3 [null_blk] null_exit+0x5c/0x95 [null_blk] __se_sys_delete_module+0x204/0x337 ? free_module+0x39f/0x39f ? blkcg_maybe_throttle_current+0x8a/0x718 ? rwlock_bug+0x62/0x62 ? __blkcg_punt_bio_submit+0xd0/0xd0 ? trace_hardirqs_on_thunk+0x1a/0x20 ? mark_held_locks+0x1f/0x7a ? do_syscall_64+0x4c/0x295 do_syscall_64+0xa7/0x295 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x7fb696cdbe6b Code: 73 01 c3 48 8b 0d 1d 20 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 008 RSP: 002b:00007ffec9588788 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0 RAX: ffffffffffffffda RBX: 0000559e589137c0 RCX: 00007fb696cdbe6b RDX: 000000000000000a RSI: 0000000000000800 RDI: 0000559e58913828 RBP: 0000000000000000 R08: 00007ffec9587701 R09: 0000000000000000 R10: 00007fb696d4eae0 R11: 0000000000000206 R12: 00007ffec95889b0 R13: 00007ffec95896b3 R14: 0000559e58913260 R15: 0000559e589137c0 Cc: Christoph Hellwig <hch@infradead.org> Cc: Hannes Reinecke <hare@suse.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Mike Snitzer <snitzer@redhat.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-08-27block: add helper for checking if queue is registeredMing Lei1-1/+1
There are 4 users which check if queue is registered, so add one helper to check it. Cc: Christoph Hellwig <hch@infradead.org> Cc: Hannes Reinecke <hare@suse.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-08-27block: don't hold q->sysfs_lock in elevator_init_mqMing Lei1-9/+5
The original comment says: q->sysfs_lock must be held to provide mutual exclusion between elevator_switch() and here. Which is simply wrong. elevator_init_mq() is only called from blk_mq_init_allocated_queue, which is always called before the request queue is registered via blk_register_queue(), for dm-rq or normal rq based driver. However, queue's kobject is only exposed and added to sysfs in blk_register_queue(). So there isn't such race between elevator_switch() and elevator_init_mq(). So avoid to hold q->sysfs_lock in elevator_init_mq(). Cc: Christoph Hellwig <hch@infradead.org> Cc: Hannes Reinecke <hare@suse.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Mike Snitzer <snitzer@redhat.com> Cc: Bart Van Assche <bvanassche@acm.org> Cc: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-06-06block: free sched's request pool in blk_cleanup_queueMing Lei1-1/+1
In theory, IO scheduler belongs to request queue, and the request pool of sched tags belongs to the request queue too. However, the current tags allocation interfaces are re-used for both driver tags and sched tags, and driver tags is definitely host wide, and doesn't belong to any request queue, same with its request pool. So we need tagset instance for freeing request of sched tags. Meantime, blk_mq_free_tag_set() often follows blk_cleanup_queue() in case of non-BLK_MQ_F_TAG_SHARED, this way requires that request pool of sched tags to be freed before calling blk_mq_free_tag_set(). Commit 47cdee29ef9d94e ("block: move blk_exit_queue into __blk_release_queue") moves blk_exit_queue into __blk_release_queue for simplying the fast path in generic_make_request(), then causes oops during freeing requests of sched tags in __blk_release_queue(). Fix the above issue by move freeing request pool of sched tags into blk_cleanup_queue(), this way is safe becasue queue has been frozen and no any in-queue requests at that time. Freeing sched tags has to be kept in queue's release handler becasue there might be un-completed dispatch activity which might refer to sched tags. Cc: Bart Van Assche <bvanassche@acm.org> Cc: Christoph Hellwig <hch@lst.de> Fixes: 47cdee29ef9d94e485eb08f962c74943023a5271 ("block: move blk_exit_queue into __blk_release_queue") Tested-by: Yi Zhang <yi.zhang@redhat.com> Reported-by: kernel test robot <rong.a.chen@intel.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-30block: 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>
2019-04-08block: remove unused variable 'def'Hisao Tanabe1-4/+2
The 'def' local variable became unused after commit f382fb0bcef4 ("block: remove legacy IO schedulers"), let's remove it. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Hisao Tanabe <xtanabe@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-02-11block: avoid setting none scheduler if it's already noneAleksei Zakharov1-1/+4
There's no reason to freeze queue and remove scheduler if there's no scheduler already. Signed-off-by: Aleksei Zakharov <zakharov.a.g@yandex.ru> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-16block: add queue_is_mq() helperJens Axboe1-6/+5
Various spots check for q->mq_ops being non-NULL, but provide a helper to do this instead. Where the ->mq_ops != NULL check is redundant, remove it. Since mq == rq-based now that legacy is gone, get rid of the queue_is_rq_based() and just use queue_is_mq() everywhere. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-14block: clean up dead code that is now redundantColin Ian King1-7/+0
The boolean next_sorted is set to false and is never changed, hence the code that checks if it is true is dead code and can now be removed. This dead code occurred from a previous commit that cleaned up the elevator and removed the setting of next_sorted to true. Detected by CoverityScan, CID#1475401 ("'Constant' variable guards dead code") Fixes: a1ce35fa4985 ("block: remove dead elevator code") Signed-off-by: Colin Ian King <colin.king@canonical.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07block: get rid of MQ scheduler ops unionJens Axboe1-13/+13
This is a remnant of when we had ops for both SQ and MQ schedulers. Now it's just MQ, so get rid of the union. Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07block: remove dead elevator codeJens Axboe1-355/+22
This removes a bunch of core and elevator related code. On the core front, we remove anything related to queue running, draining, initialization, plugging, and congestions. We also kill anything related to request allocation, merging, retrieval, and completion. Remove any checking for single queue IO schedulers, as they no longer exist. This means we can also delete a bunch of code related to request issue, adding, completion, etc - and all the SQ related ops and helpers. Also kill the load_default_modules(), as all that did was provide for a way to load the default single queue elevator. Tested-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07block: remove legacy IO schedulersJens Axboe1-70/+0
Retain the deadline documentation, as that carries over to mq-deadline as well. 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 Axboe1-1/+1
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>
2018-09-26block: fix deadline elevator drain for zoned block devicesDamien Le Moal1-1/+1
When the deadline scheduler is used with a zoned block device, writes to a zone will be dispatched one at a time. This causes the warning message: deadline: forced dispatching is broken (nr_sorted=X), please report this to be displayed when switching to another elevator with the legacy I/O path while write requests to a zone are being retained in the scheduler queue. Prevent this message from being displayed when executing elv_drain_elevator() for a zoned block device. __blk_drain_queue() will loop until all writes are dispatched and completed, resulting in the desired elevator queue drain without extensive modifications to the deadline code itself to handle forced-dispatch calls. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Fixes: 8dc8146f9c92 ("deadline-iosched: Introduce zone locking support") Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-26block: Schedule runtime resume earlierBart Van Assche1-1/+0
Instead of scheduling runtime resume of a request queue after a request has been queued, schedule asynchronous resume during request allocation. The new pm_request_resume() calls occur after blk_queue_enter() has increased the q_usage_counter request queue member. This change is needed for a later patch that will make request allocation block while the queue status is not RPM_ACTIVE. Signed-off-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Jianchao Wang <jianchao.w.wang@oracle.com> Cc: Hannes Reinecke <hare@suse.com> Cc: Johannes Thumshirn <jthumshirn@suse.de> Cc: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-26block: Split blk_pm_add_request() and blk_pm_put_request()Bart Van Assche1-0/+1
Move the pm_request_resume() and pm_runtime_mark_last_busy() calls into two new functions and thereby separate legacy block layer code from code that works for both the legacy block layer and blk-mq. A later patch will add calls to the new functions in the blk-mq code. Signed-off-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: Jianchao Wang <jianchao.w.wang@oracle.com> Cc: Hannes Reinecke <hare@suse.com> Cc: Johannes Thumshirn <jthumshirn@suse.de> Cc: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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