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2018-01-10block, bfq: fix occurrences of request finish method's old nameChiara Bruschi
Commit '7b9e93616399' ("blk-mq-sched: unify request finished methods") changed the old name of current bfq_finish_request method, but left it unchanged elsewhere in the code (related comments, part of function name bfq_put_rq_priv_body). This commit fixes all occurrences of the old name of this method by changing them into the current name. Fixes: 7b9e93616399 ("blk-mq-sched: unify request finished methods") Reviewed-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Federico Motta <federico@willer.it> Signed-off-by: Chiara Bruschi <bruschi.chiara@outlook.it> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09Revert "block: blk-merge: try to make front segments in full size"Ming Lei
This reverts commit a2d37968d784363842f87820a21e106741d28004. If max segment size isn't 512-aligned, this patch won't work well. Also once multipage bvec is enabled, adjacent bvecs won't be physically contiguous if page is added via bio_add_page(), so we don't need this kind of complicated logic. Reported-by: Dmitry Osipenko <digetx@gmail.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09bfq-iosched: don't call bfqg_and_blkg_put for !CONFIG_BFQ_GROUP_IOSCHEDJens Axboe
It's not available if we don't have group io scheduling set, and there's no need to call it. Fixes: 0d52af590552 ("block, bfq: release oom-queue ref to root group on exit") Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09block: Fix kernel-doc warnings reported when building with W=1Bart Van Assche
Commit 3a025e1d1c2e ("Add optional check for bad kernel-doc comments") causes W=1 the kernel-doc script to be run and thereby causes several new warnings to appear when building the kernel with W=1. Fix the block layer kernel-doc headers such that the block layer again builds cleanly with W=1. Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com> Cc: Martin K. Petersen <martin.petersen@oracle.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Hannes Reinecke <hare@suse.de> Cc: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09blk-mq: Fix spelling in a source code commentBart Van Assche
Change "nedeing" into "needing" and "caes" into "cases". Fixes: commit f906a6a0f426 ("blk-mq: improve tag waiting setup for non-shared tags") Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Omar Sandoval <osandov@fb.com> Cc: Hannes Reinecke <hare@suse.de> Cc: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09blk-mq: silence false positive warnings in hctx_unlock()Jens Axboe
In some stupider versions of gcc, it complains: block/blk-mq.c: In function ‘blk_mq_complete_request’: ./include/linux/srcu.h:175:2: warning: ‘srcu_idx’ may be used uninitialized in this function [-Wmaybe-uninitialized] __srcu_read_unlock(sp, idx); ^ block/blk-mq.c:620:6: note: ‘srcu_idx’ was declared here int srcu_idx; ^ which is completely bogus, since we only use srcu_idx when hctx->flags & BLK_MQ_F_BLOCKING is set, and that's the case where hctx_lock() has initialized it. Just set it to '0' in the normal path in hctx_lock() to silence this annoying warning. Fixes: 04ced159cec8 ("blk-mq: move hctx lock/unlock into a helper") Fixes: 5197c05e16b4 ("blk-mq: protect completion path with RCU") Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09blk-mq: rename blk_mq_hw_ctx->queue_rq_srcu to ->srcuTejun Heo
The RCU protection has been expanded to cover both queueing and completion paths making ->queue_rq_srcu a misnomer. Rename it to ->srcu as suggested by Bart. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Bart Van Assche <Bart.VanAssche@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09blk-mq: remove REQ_ATOM_STARTEDTejun Heo
After the recent updates to use generation number and state based synchronization, we can easily replace REQ_ATOM_STARTED usages by adding an extra state to distinguish completed but not yet freed state. Add MQ_RQ_COMPLETE and replace REQ_ATOM_STARTED usages with blk_mq_rq_state() tests. REQ_ATOM_STARTED no longer has any users left and is removed. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09blk-mq: remove REQ_ATOM_COMPLETE usages from blk-mqTejun Heo
After the recent updates to use generation number and state based synchronization, blk-mq no longer depends on REQ_ATOM_COMPLETE except to avoid firing the same timeout multiple times. Remove all REQ_ATOM_COMPLETE usages and use a new rq_flags flag RQF_MQ_TIMEOUT_EXPIRED to avoid firing the same timeout multiple times. This removes atomic bitops from hot paths too. v2: Removed blk_clear_rq_complete() from blk_mq_rq_timed_out(). v3: Added RQF_MQ_TIMEOUT_EXPIRED flag. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: "jianchao.wang" <jianchao.w.wang@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09blk-mq: make blk_abort_request() trigger timeout pathTejun Heo
With issue/complete and timeout paths now using the generation number and state based synchronization, blk_abort_request() is the only one which depends on REQ_ATOM_COMPLETE for arbitrating completion. There's no reason for blk_abort_request() to be a completely separate path. This patch makes blk_abort_request() piggyback on the timeout path instead of trying to terminate the request directly. This removes the last dependency on REQ_ATOM_COMPLETE in blk-mq. Note that this makes blk_abort_request() asynchronous - it initiates abortion but the actual termination will happen after a short while, even when the caller owns the request. AFAICS, SCSI and ATA should be fine with that and I think mtip32xx and dasd should be safe but not completely sure. It'd be great if people who know the drivers take a look. v2: - Add comment explaining the lack of synchronization around ->deadline update as requested by Bart. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Asai Thambi SP <asamymuthupa@micron.com> Cc: Stefan Haberland <sth@linux.vnet.ibm.com> Cc: Jan Hoeppner <hoeppner@linux.vnet.ibm.com> Cc: Bart Van Assche <Bart.VanAssche@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09blk-mq: use blk_mq_rq_state() instead of testing REQ_ATOM_COMPLETETejun Heo
blk_mq_check_inflight() and blk_mq_poll_hybrid_sleep() test REQ_ATOM_COMPLETE to determine the request state. Both uses are speculative and we can test REQ_ATOM_STARTED and blk_mq_rq_state() for equivalent results. Replace the tests. This will allow removing REQ_ATOM_COMPLETE usages from blk-mq. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09blk-mq: replace timeout synchronization with a RCU and generation based schemeTejun Heo
Currently, blk-mq timeout path synchronizes against the usual issue/completion path using a complex scheme involving atomic bitflags, REQ_ATOM_*, memory barriers and subtle memory coherence rules. Unfortunately, it contains quite a few holes. There's a complex dancing around REQ_ATOM_STARTED and REQ_ATOM_COMPLETE between issue/completion and timeout paths; however, they don't have a synchronization point across request recycle instances and it isn't clear what the barriers add. blk_mq_check_expired() can easily read STARTED from N-2'th iteration, deadline from N-1'th, blk_mark_rq_complete() against Nth instance. In fact, it's pretty easy to make blk_mq_check_expired() terminate a later instance of a request. If we induce 5 sec delay before time_after_eq() test in blk_mq_check_expired(), shorten the timeout to 2s, and issue back-to-back large IOs, blk-mq starts timing out requests spuriously pretty quickly. Nothing actually timed out. It just made the call on a recycle instance of a request and then terminated a later instance long after the original instance finished. The scenario isn't theoretical either. This patch replaces the broken synchronization mechanism with a RCU and generation number based one. 1. Each request has a u64 generation + state value, which can be updated only by the request owner. Whenever a request becomes in-flight, the generation number gets bumped up too. This provides the basis for the timeout path to distinguish different recycle instances of the request. Also, marking a request in-flight and setting its deadline are protected with a seqcount so that the timeout path can fetch both values coherently. 2. The timeout path fetches the generation, state and deadline. If the verdict is timeout, it records the generation into a dedicated request abortion field and does RCU wait. 3. The completion path is also protected by RCU (from the previous patch) and checks whether the current generation number and state match the abortion field. If so, it skips completion. 4. The timeout path, after RCU wait, scans requests again and terminates the ones whose generation and state still match the ones requested for abortion. By now, the timeout path knows that either the generation number and state changed if it lost the race or the completion will yield to it and can safely timeout the request. While it's more lines of code, it's conceptually simpler, doesn't depend on direct use of subtle memory ordering or coherence, and hopefully doesn't terminate the wrong instance. While this change makes REQ_ATOM_COMPLETE synchronization unnecessary between issue/complete and timeout paths, REQ_ATOM_COMPLETE isn't removed yet as it's still used in other places. Future patches will move all state tracking to the new mechanism and remove all bitops in the hot paths. Note that this patch adds a comment explaining a race condition in BLK_EH_RESET_TIMER path. The race has always been there and this patch doesn't change it. It's just documenting the existing race. v2: - Fixed BLK_EH_RESET_TIMER handling as pointed out by Jianchao. - s/request->gstate_seqc/request->gstate_seq/ as suggested by Peter. - READ_ONCE() added in blk_mq_rq_update_state() as suggested by Peter. v3: - Fixed possible extended seqcount / u64_stats_sync read looping spotted by Peter. - MQ_RQ_IDLE was incorrectly being set in complete_request instead of free_request. Fixed. v4: - Rebased on top of hctx_lock() refactoring patch. - Added comment explaining the use of hctx_lock() in completion path. v5: - Added comments requested by Bart. - Note the addition of BLK_EH_RESET_TIMER race condition in the commit message. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: "jianchao.wang" <jianchao.w.wang@oracle.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Bart Van Assche <Bart.VanAssche@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09blk-mq: protect completion path with RCUTejun Heo
Currently, blk-mq protects only the issue path with RCU. This patch puts the completion path under the same RCU protection. This will be used to synchronize issue/completion against timeout by later patches, which will also add the comments. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09blk-mq: move hctx lock/unlock into a helperJens Axboe
Move the RCU vs SRCU logic into lock/unlock helpers, which makes the actual functional bits within the locked region much easier to read. tj: Reordered in front of timeout revamp patches and added the missing blk_mq_run_hw_queue() conversion. Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09block, bfq: release oom-queue ref to root group on exitPaolo Valente
On scheduler init, a reference to the root group, and a reference to its corresponding blkg are taken for the oom queue. Yet these references are not released on scheduler exit, which prevents these objects from be freed. This commit adds the missing reference releases. Reported-by: Davide Ferrari <davideferrari8@gmail.com> Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09block, bfq: put async queues for root bfq groups tooPaolo Valente
For each pair [device for which bfq is selected as I/O scheduler, group in blkio/io], bfq maintains a corresponding bfq group. Each such bfq group contains a set of async queues, with each async queue created on demand, i.e., when some I/O request arrives for it. On creation, an async queue gets an extra reference, to make sure that the queue is not freed as long as its bfq group exists. Accordingly, to allow the queue to be freed after the group exited, this extra reference must released on group exit. The above holds also for a bfq root group, i.e., for the bfq group corresponding to the root blkio/io root for a given device. Yet, by mistake, the references to the existing async queues of a root group are not released when the latter exits. This causes a memory leak when the instance of bfq for a given device exits. In a similar vein, bfqg_stats_xfer_dead is not executed for a root group. This commit fixes bfq_pd_offline so that the latter executes the above missing operations for a root group too. Reported-by: Holger Hoffstätte <holger@applied-asynchrony.com> Reported-by: Guoqing Jiang <gqjiang@suse.com> Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Signed-off-by: Davide Ferrari <davideferrari8@gmail.com> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-09blk-mq: fix kernel oops in blk_mq_tag_idle()Ming Lei
HW queues may be unmapped in some cases, such as blk_mq_update_nr_hw_queues(), then we need to check it before calling blk_mq_tag_idle(), otherwise the following kernel oops can be triggered, so fix it by checking if the hw queue is unmapped since it doesn't make sense to idle the tags any more after hw queues are unmapped. [ 440.771298] Workqueue: nvme-wq nvme_rdma_del_ctrl_work [nvme_rdma] [ 440.779104] task: ffff894bae755ee0 ti: ffff893bf9bc8000 task.ti: ffff893bf9bc8000 [ 440.788359] RIP: 0010:[<ffffffffb730e2b4>] [<ffffffffb730e2b4>] __blk_mq_tag_idle+0x24/0x40 [ 440.798697] RSP: 0018:ffff893bf9bcbd10 EFLAGS: 00010286 [ 440.805538] RAX: 0000000000000000 RBX: ffff895bb131dc00 RCX: 000000000000011f [ 440.814426] RDX: 00000000ffffffff RSI: 0000000000000120 RDI: ffff895bb131dc00 [ 440.823301] RBP: ffff893bf9bcbd10 R08: 000000000001b860 R09: 4a51d361c00c0000 [ 440.832193] R10: b5907f32b4cc7003 R11: ffffd6cabfb57000 R12: ffff894bafd1e008 [ 440.841091] R13: 0000000000000001 R14: ffff895baf770000 R15: 0000000000000080 [ 440.849988] FS: 0000000000000000(0000) GS:ffff894bbdcc0000(0000) knlGS:0000000000000000 [ 440.859955] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 440.867274] CR2: 0000000000000008 CR3: 000000103d098000 CR4: 00000000001407e0 [ 440.876169] Call Trace: [ 440.879818] [<ffffffffb7309d68>] blk_mq_exit_hctx+0xd8/0xe0 [ 440.887051] [<ffffffffb730dc40>] blk_mq_free_queue+0xf0/0x160 [ 440.894465] [<ffffffffb72ff679>] blk_cleanup_queue+0xd9/0x150 [ 440.901881] [<ffffffffc08a802b>] nvme_ns_remove+0x5b/0xb0 [nvme_core] [ 440.910068] [<ffffffffc08a811b>] nvme_remove_namespaces+0x3b/0x60 [nvme_core] [ 440.919026] [<ffffffffc08b817b>] __nvme_rdma_remove_ctrl+0x2b/0xb0 [nvme_rdma] [ 440.928079] [<ffffffffc08b8237>] nvme_rdma_del_ctrl_work+0x17/0x20 [nvme_rdma] [ 440.937126] [<ffffffffb70ab58a>] process_one_work+0x17a/0x440 [ 440.944517] [<ffffffffb70ac3a8>] worker_thread+0x278/0x3c0 [ 440.951607] [<ffffffffb70ac130>] ? manage_workers.isra.24+0x2a0/0x2a0 [ 440.959760] [<ffffffffb70b352f>] kthread+0xcf/0xe0 [ 440.966055] [<ffffffffb70b3460>] ? insert_kthread_work+0x40/0x40 [ 440.973715] [<ffffffffb76d8658>] ret_from_fork+0x58/0x90 [ 440.980586] [<ffffffffb70b3460>] ? insert_kthread_work+0x40/0x40 [ 440.988229] Code: 5b 41 5c 5d c3 66 90 0f 1f 44 00 00 48 8b 87 20 01 00 00 f0 0f ba 77 40 01 19 d2 85 d2 75 08 c3 0f 1f 80 00 00 00 00 55 48 89 e5 <f0> ff 48 08 48 8d 78 10 e8 7f 0f 05 00 5d c3 0f 1f 00 66 2e 0f [ 441.011620] RIP [<ffffffffb730e2b4>] __blk_mq_tag_idle+0x24/0x40 [ 441.019301] RSP <ffff893bf9bcbd10> [ 441.024052] CR2: 0000000000000008 Reported-by: Zhang Yi <yizhan@redhat.com> Tested-by: Zhang Yi <yizhan@redhat.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-06blk-mq: fix race between updating nr_hw_queues and switching io schedMing Lei
In both elevator_switch_mq() and blk_mq_update_nr_hw_queues(), sched tags can be allocated, and q->nr_hw_queue is used, and race is inevitable, for example: blk_mq_init_sched() may trigger use-after-free on hctx, which is freed in blk_mq_realloc_hw_ctxs() when nr_hw_queues is decreased. This patch fixes the race be holding q->sysfs_lock. Reviewed-by: Christoph Hellwig <hch@lst.de> Reported-by: Yi Zhang <yi.zhang@redhat.com> Tested-by: Yi Zhang <yi.zhang@redhat.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-06blk-mq: avoid to map CPU into stale hw queueMing Lei
blk_mq_pci_map_queues() may not map one CPU into any hw queue, but its previous map isn't cleared yet, and may point to one stale hw queue index. This patch fixes the following issue by clearing the mapping table before setting it up in blk_mq_pci_map_queues(). This patches fixes this following issue reported by Zhang Yi: [ 101.202734] BUG: unable to handle kernel NULL pointer dereference at 0000000094d3013f [ 101.211487] IP: blk_mq_map_swqueue+0xbc/0x200 [ 101.216346] PGD 0 P4D 0 [ 101.219171] Oops: 0000 [#1] SMP [ 101.222674] Modules linked in: sunrpc ipmi_ssif vfat fat intel_rapl sb_edac x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel intel_cstate intel_uncore mxm_wmi intel_rapl_perf iTCO_wdt ipmi_si ipmi_devintf pcspkr iTCO_vendor_support sg dcdbas ipmi_msghandler wmi mei_me lpc_ich shpchp mei acpi_power_meter dm_multipath ip_tables xfs libcrc32c sd_mod mgag200 i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm ahci libahci crc32c_intel libata tg3 nvme nvme_core megaraid_sas ptp i2c_core pps_core dm_mirror dm_region_hash dm_log dm_mod [ 101.284881] CPU: 0 PID: 504 Comm: kworker/u25:5 Not tainted 4.15.0-rc2 #1 [ 101.292455] Hardware name: Dell Inc. PowerEdge R730xd/072T6D, BIOS 2.5.5 08/16/2017 [ 101.301001] Workqueue: nvme-wq nvme_reset_work [nvme] [ 101.306636] task: 00000000f2c53190 task.stack: 000000002da874f9 [ 101.313241] RIP: 0010:blk_mq_map_swqueue+0xbc/0x200 [ 101.318681] RSP: 0018:ffffc9000234fd70 EFLAGS: 00010282 [ 101.324511] RAX: ffff88047ffc9480 RBX: ffff88047e130850 RCX: 0000000000000000 [ 101.332471] RDX: ffffe8ffffd40580 RSI: ffff88047e509b40 RDI: ffff88046f37a008 [ 101.340432] RBP: 000000000000000b R08: ffff88046f37a008 R09: 0000000011f94280 [ 101.348392] R10: ffff88047ffd4d00 R11: 0000000000000000 R12: ffff88046f37a008 [ 101.356353] R13: ffff88047e130f38 R14: 000000000000000b R15: ffff88046f37a558 [ 101.364314] FS: 0000000000000000(0000) GS:ffff880277c00000(0000) knlGS:0000000000000000 [ 101.373342] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 101.379753] CR2: 0000000000000098 CR3: 000000047f409004 CR4: 00000000001606f0 [ 101.387714] Call Trace: [ 101.390445] blk_mq_update_nr_hw_queues+0xbf/0x130 [ 101.395791] nvme_reset_work+0x6f4/0xc06 [nvme] [ 101.400848] ? pick_next_task_fair+0x290/0x5f0 [ 101.405807] ? __switch_to+0x1f5/0x430 [ 101.409988] ? put_prev_entity+0x2f/0xd0 [ 101.414365] process_one_work+0x141/0x340 [ 101.418836] worker_thread+0x47/0x3e0 [ 101.422921] kthread+0xf5/0x130 [ 101.426424] ? rescuer_thread+0x380/0x380 [ 101.430896] ? kthread_associate_blkcg+0x90/0x90 [ 101.436048] ret_from_fork+0x1f/0x30 [ 101.440034] Code: 48 83 3c ca 00 0f 84 2b 01 00 00 48 63 cd 48 8b 93 10 01 00 00 8b 0c 88 48 8b 83 20 01 00 00 4a 03 14 f5 60 04 af 81 48 8b 0c c8 <48> 8b 81 98 00 00 00 f0 4c 0f ab 30 8b 81 f8 00 00 00 89 42 44 [ 101.461116] RIP: blk_mq_map_swqueue+0xbc/0x200 RSP: ffffc9000234fd70 [ 101.468205] CR2: 0000000000000098 [ 101.471907] ---[ end trace 5fe710f98228a3ca ]--- [ 101.482489] Kernel panic - not syncing: Fatal exception [ 101.488505] Kernel Offset: disabled [ 101.497752] ---[ end Kernel panic - not syncing: Fatal exception Reviewed-by: Christoph Hellwig <hch@lst.de> Suggested-by: Christoph Hellwig <hch@lst.de> Reported-by: Yi Zhang <yi.zhang@redhat.com> Tested-by: Yi Zhang <yi.zhang@redhat.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-06blk-mq: quiesce queue during switching io sched and updating nr_requestsMing Lei
Dispatch may still be in-progress after queue is frozen, so we have to quiesce queue before switching IO scheduler and updating nr_requests. Also when switching io schedulers, blk_mq_run_hw_queue() may still be called somewhere(such as from nvme_reset_work()), and io scheduler's per-hctx data may not be setup yet, so cause oops even inside blk_mq_hctx_has_pending(), such as it can be run just between: ret = e->ops.mq.init_sched(q, e); AND ret = e->ops.mq.init_hctx(hctx, i) inside blk_mq_init_sched(). This reverts commit 7a148c2fcff8330(block: don't call blk_mq_quiesce_queue() after queue is frozen) basically, and makes sure blk_mq_hctx_has_pending won't be called if queue is quiesced. Reviewed-by: Christoph Hellwig <hch@lst.de> Fixes: 7a148c2fcff83309(block: don't call blk_mq_quiesce_queue() after queue is frozen) Reported-by: Yi Zhang <yi.zhang@redhat.com> Tested-by: Yi Zhang <yi.zhang@redhat.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-06blk-mq: quiesce queue before freeing queueMing Lei
After queue is frozen, dispatch still may happen, for example: 1) requests are submitted from several contexts 2) requests from all these contexts are inserted to queue, but may dispatch to LLD in one of these paths, but other paths sill need to move on even all these requests are completed(that means blk_mq_freeze_queue_wait() returns at that time) 3) dispatch after queue freezing still moves on and causes use-after-free, because request queue is freed This patch quiesces queue after it is frozen, and makes sure all in-progress dispatch are completed. This patch fixes the following kernel crash when running heavy IOs vs. deleting device: [ 36.719251] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 [ 36.720318] IP: kyber_has_work+0x14/0x40 [ 36.720847] PGD 254bf5067 P4D 254bf5067 PUD 255e6a067 PMD 0 [ 36.721584] Oops: 0000 [#1] PREEMPT SMP [ 36.722105] Dumping ftrace buffer: [ 36.722570] (ftrace buffer empty) [ 36.723057] Modules linked in: scsi_debug ebtable_filter ebtables ip6table_filter ip6_tables tcm_loop iscsi_target_mod target_core_file target_core_iblock target_core_pscsi target_core_mod xt_CHECKSUM iptable_mangle ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack libcrc32c bridge stp llc fuse iptable_filter ip_tables sd_mod sg btrfs xor zstd_decompress zstd_compress xxhash raid6_pq mptsas mptscsih bcache crc32c_intel ahci mptbase libahci serio_raw scsi_transport_sas nvme libata shpchp lpc_ich virtio_scsi nvme_core binfmt_misc dm_mod iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi null_blk configs [ 36.733438] CPU: 2 PID: 2374 Comm: fio Not tainted 4.15.0-rc2.blk_mq_quiesce+ #714 [ 36.735143] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.9.3-1.fc25 04/01/2014 [ 36.736688] RIP: 0010:kyber_has_work+0x14/0x40 [ 36.737515] RSP: 0018:ffffc9000209bca0 EFLAGS: 00010202 [ 36.738431] RAX: 0000000000000008 RBX: ffff88025578bfc8 RCX: ffff880257bf4ed0 [ 36.739581] RDX: 0000000000000038 RSI: ffffffff81a98c6d RDI: ffff88025578bfc8 [ 36.740730] RBP: ffff880253cebfc8 R08: ffffc9000209bda0 R09: ffff8802554f3480 [ 36.741885] R10: ffffc9000209be60 R11: ffff880263f72538 R12: ffff88025573e9e8 [ 36.743036] R13: ffff88025578bfd0 R14: 0000000000000001 R15: 0000000000000000 [ 36.744189] FS: 00007f9b9bee67c0(0000) GS:ffff88027fc80000(0000) knlGS:0000000000000000 [ 36.746617] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 36.748483] CR2: 0000000000000008 CR3: 0000000254bf4001 CR4: 00000000003606e0 [ 36.750164] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 36.751455] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 36.752796] Call Trace: [ 36.753992] blk_mq_do_dispatch_sched+0x7f/0xe0 [ 36.755110] blk_mq_sched_dispatch_requests+0x119/0x190 [ 36.756179] __blk_mq_run_hw_queue+0x83/0x90 [ 36.757144] __blk_mq_delay_run_hw_queue+0xaf/0x110 [ 36.758046] blk_mq_run_hw_queue+0x24/0x70 [ 36.758845] blk_mq_flush_plug_list+0x1e7/0x270 [ 36.759676] blk_flush_plug_list+0xd6/0x240 [ 36.760463] blk_finish_plug+0x27/0x40 [ 36.761195] do_io_submit+0x19b/0x780 [ 36.761921] ? entry_SYSCALL_64_fastpath+0x1a/0x7d [ 36.762788] entry_SYSCALL_64_fastpath+0x1a/0x7d [ 36.763639] RIP: 0033:0x7f9b9699f697 [ 36.764352] RSP: 002b:00007ffc10f991b8 EFLAGS: 00000206 ORIG_RAX: 00000000000000d1 [ 36.765773] RAX: ffffffffffffffda RBX: 00000000008f6f00 RCX: 00007f9b9699f697 [ 36.766965] RDX: 0000000000a5e6c0 RSI: 0000000000000001 RDI: 00007f9b8462a000 [ 36.768377] RBP: 0000000000000000 R08: 0000000000000001 R09: 00000000008f6420 [ 36.769649] R10: 00007f9b846e5000 R11: 0000000000000206 R12: 00007f9b795d6a70 [ 36.770807] R13: 00007f9b795e4140 R14: 00007f9b795e3fe0 R15: 0000000100000000 [ 36.771955] Code: 83 c7 10 e9 3f 68 d1 ff 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 8b 97 b0 00 00 00 48 8d 42 08 48 83 c2 38 <48> 3b 00 74 06 b8 01 00 00 00 c3 48 3b 40 08 75 f4 48 83 c0 10 [ 36.775004] RIP: kyber_has_work+0x14/0x40 RSP: ffffc9000209bca0 [ 36.776012] CR2: 0000000000000008 [ 36.776690] ---[ end trace 4045cbce364ff2a4 ]--- [ 36.777527] Kernel panic - not syncing: Fatal exception [ 36.778526] Dumping ftrace buffer: [ 36.779313] (ftrace buffer empty) [ 36.780081] Kernel Offset: disabled [ 36.780877] ---[ end Kernel panic - not syncing: Fatal exception Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: stable@vger.kernel.org Tested-by: Yi Zhang <yi.zhang@redhat.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-06mq-deadline: make it clear that __dd_dispatch_request() works on all hw queuesJens Axboe
Don't pass in the hardware queue to __dd_dispatch_request(), since it leads the reader to believe that we are returning a request for that specific hardware queue. That's not how mq-deadline works, the state for determining which request to serve next is shared across all hardware queues for a device. Reviewed-by: Omar Sandoval <osandov@fb.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-06block: blk-merge: remove unnecessary checkMing Lei
In this case, 'sectors' can't be zero at all, so remove the check and let the bio be split. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-06block: blk-merge: try to make front segments in full sizeMing Lei
When merging one bvec into segment, if the bvec is too big to merge, current policy is to move the whole bvec into another new segment. This patchset changes the policy into trying to maximize size of front segments, that means in above situation, part of bvec is merged into current segment, and the remainder is put into next segment. This patch prepares for support multipage bvec because it can be quite common to see this case and we should try to make front segments in full size. Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-06blk-merge: compute bio->bi_seg_front_size efficientlyMing Lei
It is enough to check and compute bio->bi_seg_front_size just after the 1st segment is found, but current code checks that for each bvec, which is inefficient. This patch follows the way in __blk_recalc_rq_segments() for computing bio->bi_seg_front_size, and it is more efficient and code becomes more readable too. Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-06block: move bio_alloc_pages() to bcacheMing Lei
bcache is the only user of bio_alloc_pages(), so move this function into bcache, and avoid it being misused in the future. Also rename it to bch_bio_allo_pages() since it is bcache only. Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-06block: bounce: don't access bio->bi_io_vec in copy_to_high_bio_irqMing Lei
Firstly this patch introduces BVEC_ITER_ALL_INIT for iterating one bio from start to end. As we need to support multipage bvecs, don't access bio->bi_io_vec in copy_to_high_bio_irq(), and just use the standard iterator for that. Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-06block: bounce: avoid direct access to bvec tableMing Lei
We will support multipage bvecs in the future, so change to iterator way for getting bv_page of bvec from original bio. Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-05block, bfq: remove batches of confusing ifdefsPaolo Valente
Commit a33801e8b473 ("block, bfq: move debug blkio stats behind CONFIG_DEBUG_BLK_CGROUP") introduced two batches of confusing ifdefs: one reported in [1], plus a similar one in another function. This commit removes both batches, in the way suggested in [1]. [1] https://www.spinics.net/lists/linux-block/msg20043.html Fixes: a33801e8b473 ("block, bfq: move debug blkio stats behind CONFIG_DEBUG_BLK_CGROUP") Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Tested-by: Luca Miccio <lucmiccio@gmail.com> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-05block, bfq: consider also past I/O in soft real-time detectionPaolo Valente
BFQ privileges the I/O of soft real-time applications, such as video players, to guarantee to these application a high bandwidth and a low latency. In this respect, it is not easy to correctly detect when an application is soft real-time. A particularly nasty false positive is that of an I/O-bound application that occasionally happens to meet all requirements to be deemed as soft real-time. After being detected as soft real-time, such an application monopolizes the device. Fortunately, BFQ will realize soon that the application is actually not soft real-time and suspend every privilege. Yet, the application may happen again to be wrongly detected as soft real-time, and so on. As highlighted by our tests, this problem causes BFQ to occasionally fail to guarantee a high responsiveness, in the presence of heavy background I/O workloads. The reason is that the background workload happens to be detected as soft real-time, more or less frequently, during the execution of the interactive task under test. To give an idea, because of this problem, Libreoffice Writer occasionally takes 8 seconds, instead of 3, to start up, if there are sequential reads and writes in the background, on a Kingston SSDNow V300. This commit addresses this issue by leveraging the following facts. The reason why some applications are detected as soft real-time despite all BFQ checks to avoid false positives, is simply that, during high CPU or storage-device load, I/O-bound applications may happen to do I/O slowly enough to meet all soft real-time requirements, and pass all BFQ extra checks. Yet, this happens only for limited time periods: slow-speed time intervals are usually interspersed between other time intervals during which these applications do I/O at a very high speed. To exploit these facts, this commit introduces a little change, in the detection of soft real-time behavior, to systematically consider also the recent past: the higher the speed was in the recent past, the later next I/O should arrive for the application to be considered as soft real-time. At the beginning of a slow-speed interval, the minimum arrival time allowed for the next I/O usually happens to still be so high, to fall *after* the end of the slow-speed period itself. As a consequence, the application does not risk to be deemed as soft real-time during the slow-speed interval. Then, during the next high-speed interval, the application cannot, evidently, be deemed as soft real-time (exactly because of its speed), and so on. This extra filtering proved to be rather effective: in the above test, the frequency of false positives became so low that the start-up time was 3 seconds in all iterations (apart from occasional outliers, caused by page-cache-management issues, which are out of the scope of this commit, and cannot be solved by an I/O scheduler). Tested-by: Lee Tibbert <lee.tibbert@gmail.com> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-05block, bfq: remove superfluous check in queue-merging setupAngelo Ruocco
When two or more processes do I/O in a way that the their requests are sequential in respect to one another, BFQ merges the bfq_queues associated with the processes. This way the overall I/O pattern becomes sequential, and thus there is a boost in througput. These cooperating processes usually start or restart to do I/O shortly after each other. So, in order to avoid merging non-cooperating processes, BFQ ensures that none of these queues has been in weight raising for too long. In this respect, from commit "block, bfq-sq, bfq-mq: let a queue be merged only shortly after being created", BFQ checks whether any queue (and not only weight-raised ones) is doing I/O continuously from too long to be merged. This new additional check makes the first one useless: a queue doing I/O from long enough, if being weight-raised, is also a queue in weight raising for too long to be merged. Accordingly, this commit removes the first check. Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com> Signed-off-by: Paolo Valente <paolo.valente@linaro.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-05block, bfq: let a queue be merged only shortly after starting I/OPaolo Valente
In BFQ and CFQ, two processes are said to be cooperating if they do I/O in such a way that the union of their I/O requests yields a sequential I/O pattern. To get such a sequential I/O pattern out of the non-sequential pattern of each cooperating process, BFQ and CFQ merge the queues associated with these processes. In more detail, cooperating processes, and thus their associated queues, usually start, or restart, to do I/O shortly after each other. This is the case, e.g., for the I/O threads of KVM/QEMU and of the dump utility. Basing on this assumption, this commit allows a bfq_queue to be merged only during a short time interval (100ms) after it starts, or re-starts, to do I/O. This filtering provides two important benefits. First, it greatly reduces the probability that two non-cooperating processes have their queues merged by mistake, if they just happen to do I/O close to each other for a short time interval. These spurious merges cause loss of service guarantees. A low-weight bfq_queue may unjustly get more than its expected share of the throughput: if such a low-weight queue is merged with a high-weight queue, then the I/O for the low-weight queue is served as if the queue had a high weight. This may damage other high-weight queues unexpectedly. For instance, because of this issue, lxterminal occasionally took 7.5 seconds to start, instead of 6.5 seconds, when some sequential readers and writers did I/O in the background on a FUJITSU MHX2300BT HDD. The reason is that the bfq_queues associated with some of the readers or the writers were merged with the high-weight queues of some processes that had to do some urgent but little I/O. The readers then exploited the inherited high weight for all or most of their I/O, during the start-up of terminal. The filtering introduced by this commit eliminated any outlier caused by spurious queue merges in our start-up time tests. This filtering also provides a little boost of the throughput sustainable by BFQ: 3-4%, depending on the CPU. The reason is that, once a bfq_queue cannot be merged any longer, this commit makes BFQ stop updating the data needed to handle merging for the queue. Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-05block, bfq: check low_latency flag in bfq_bfqq_save_state()Angelo Ruocco
A just-created bfq_queue will certainly be deemed as interactive on the arrival of its first I/O request, if the low_latency flag is set. Yet, if the queue is merged with another queue on the arrival of its first I/O request, it will not have the chance to be flagged as interactive. Nevertheless, if the queue is then split soon enough, it has to be flagged as interactive after the split. To handle this early-merge scenario correctly, BFQ saves the state of the queue, on the merge, as if the latter had already been deemed interactive. So, if the queue is split soon, it will get weight-raised, because the previous state of the queue is resumed on the split. Unfortunately, in the act of saving the state of the newly-created queue, BFQ doesn't check whether the low_latency flag is set, and this causes early-merged queues to be then weight-raised, on queue splits, even if low_latency is off. This commit addresses this problem by adding the missing check. Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-05block, bfq: add missing rq_pos_tree update on rq removalPaolo Valente
If two processes do I/O close to each other, then BFQ merges the bfq_queues associated with these processes, to get a more sequential I/O, and thus a higher throughput. In this respect, to detect whether two processes are doing I/O close to each other, BFQ keeps a list of the head-of-line I/O requests of all active bfq_queues. The list is ordered by initial sectors, and implemented through a red-black tree (rq_pos_tree). Unfortunately, the update of the rq_pos_tree was incomplete, because the tree was not updated on the removal of the head-of-line I/O request of a bfq_queue, in case the queue did not remain empty. This commit adds the missing update. Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-05block, bfq: increase threshold to deem I/O as randomPaolo Valente
If two processes do I/O close to each other, i.e., are cooperating processes in BFQ (and CFQ'S) nomenclature, then BFQ merges their associated bfq_queues, so as to get sequential I/O from the union of the I/O requests of the processes, and thus reach a higher throughput. A merged queue is then split if its I/O stops being sequential. In this respect, BFQ deems the I/O of a bfq_queue as (mostly) sequential only if less than 4 I/O requests are random, out of the last 32 requests inserted into the queue. Unfortunately, extensive testing (with the interleaved_io benchmark of the S suite [1], and with real applications spawning cooperating processes) has clearly shown that, with such a low threshold, only a rather low I/O throughput may be reached when several cooperating processes do I/O. In particular, the outcome of each test run was bimodal: if queue merging occurred and was stable during the test, then the throughput was close to the peak rate of the storage device, otherwise the throughput was arbitrarily low (usually around 1/10 of the peak rate with a rotational device). The probability to get the unlucky outcomes grew with the number of cooperating processes: it was already significant with 5 processes, and close to one with 7 or more processes. The cause of the low throughput in the unlucky runs was that the merged queues containing the I/O of these cooperating processes were soon split, because they contained more random I/O requests than those tolerated by the 4/32 threshold, but - that I/O would have however allowed the storage device to reach peak throughput or almost peak throughput; - in contrast, the I/O of these processes, if served individually (from separate queues) yielded a rather low throughput. So we repeated our tests with increasing values of the threshold, until we found the minimum value (19) for which we obtained maximum throughput, reliably, with at least up to 9 cooperating processes. Then we checked that the use of that higher threshold value did not cause any regression for any other benchmark in the suite [1]. This commit raises the threshold to such a higher value. [1] https://github.com/Algodev-github/S Signed-off-by: Angelo Ruocco <angeloruocco90@gmail.com> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-05deadline-iosched: Introduce zone locking supportDamien Le Moal
Introduce zone write locking to avoid write request reordering with zoned block devices. This is achieved using a finer selection of the next request to dispatch: 1) Any non-write request is always allowed to proceed. 2) Any write to a conventional zone is always allowed to proceed. 3) For a write to a sequential zone, the zone lock is first checked. a) If the zone is not locked, the write is allowed to proceed after its target zone is locked. b) If the zone is locked, the write request is skipped and the next request in the dispatch queue tested (back to step 1). For a write request that has locked its target zone, the zone is unlocked either when the request completes and the method deadline_request_completed() is called, or when the request is requeued using the method deadline_add_request(). Requests targeting a locked zone are always left in the scheduler queue to preserve the initial write order. If no write request can be dispatched, allow reads to be dispatched even if the write batch is not done. If the device used is not a zoned block device, or if zoned block device support is disabled, this patch does not modify deadline behavior. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-05deadline-iosched: Introduce dispatch helpersDamien Le Moal
Avoid directly referencing the next_rq and fifo_list arrays using the helper functions deadline_next_request() and deadline_fifo_request() to facilitate changes in the dispatch request selection in deadline_dispatch_requests() for zoned block devices. While at it, also remove the unnecessary forward declaration of the function deadline_move_request(). Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-05mq-deadline: Introduce zone locking supportDamien Le Moal
Introduce zone write locking to avoid write request reordering with zoned block devices. This is achieved using a finer selection of the next request to dispatch: 1) Any non-write request is always allowed to proceed. 2) Any write to a conventional zone is always allowed to proceed. 3) For a write to a sequential zone, the zone lock is first checked. a) If the zone is not locked, the write is allowed to proceed after its target zone is locked. b) If the zone is locked, the write request is skipped and the next request in the dispatch queue tested (back to step 1). For a write request that has locked its target zone, the zone is unlocked either when the request completes with a call to the method deadline_request_completed() or when the request is requeued using dd_insert_request(). Requests targeting a locked zone are always left in the scheduler queue to preserve the lba ordering for write requests. If no write request can be dispatched, allow reads to be dispatched even if the write batch is not done. If the device used is not a zoned block device, or if zoned block device support is disabled, this patch does not modify mq-deadline behavior. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-05mq-deadline: Introduce dispatch helpersDamien Le Moal
Avoid directly referencing the next_rq and fifo_list arrays using the helper functions deadline_next_request() and deadline_fifo_request() to facilitate changes in the dispatch request selection in __dd_dispatch_request() for zoned block devices. Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Bart Van Assche <Bart.VanAssche@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-05block: introduce zoned block devices zone write lockingChristoph Hellwig
Components relying only on the request_queue structure for accessing block devices (e.g. I/O schedulers) have a limited knowledged of the device characteristics. In particular, the device capacity cannot be easily discovered, which for a zoned block device also result in the inability to easily know the number of zones of the device (the zone size is indicated by the chunk_sectors field of the queue limits). Introduce the nr_zones field to the request_queue structure to simplify access to this information. Also, add the bitmap seq_zone_bitmap which indicates which zones of the device are sequential zones (write preferred or write required) and the bitmap seq_zones_wlock which indicates if a zone is write locked, that is, if a write request targeting a zone was dispatched to the device. These fields are initialized by the low level block device driver (sd.c for ZBC/ZAC disks). They are not initialized by stacking drivers (device mappers) handling zoned block devices (e.g. dm-linear). Using this, I/O schedulers can introduce zone write locking to control request dispatching to a zoned block device and avoid write request reordering by limiting to at most a single write request per zone outside of the scheduler at any time. Based on previous patches from Damien Le Moal. Signed-off-by: Christoph Hellwig <hch@lst.de> [Damien] * Fixed comments and identation in blkdev.h * Changed helper functions * Fixed this commit message Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-05block: drain queue before waiting for q_usage_counter becoming zeroMing Lei
Now we track legacy requests with .q_usage_counter in commit 055f6e18e08f ("block: Make q_usage_counter also track legacy requests"), but that commit never runs and drains legacy queue before waiting for this counter becoming zero, then IO hang is caused in the test of pulling disk during IO. This patch fixes the issue by draining requests before waiting for q_usage_counter becoming zero, both Mauricio and chenxiang reported this issue, and observed that it can be fixed by this patch. Link: https://marc.info/?l=linux-block&m=151192424731797&w=2 Fixes: 055f6e18e08f("block: Make q_usage_counter also track legacy requests") Cc: Wen Xiong <wenxiong@us.ibm.com> Tested-by: "chenxiang (M)" <chenxiang66@hisilicon.com> Tested-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-01-05blk-mq: remove confusing comment of blk_mq_sched_dispatch_requestsLiu Bo
Commit de1482974080 ("blk-mq: introduce .get_budget and .put_budget in blk_mq_ops") changes the function to return bool type, and then commit 1f460b63d4b3 ("blk-mq: don't restart queue when .get_budget returns BLK_STS_RESOURCE") changes it back to void, but the comment remains. Signed-off-by: Liu Bo <bo.li.liu@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-12-22blk-mq: improve heavily contended tag caseJens Axboe
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>
2017-12-20block-throttle: avoid double chargeShaohua Li
If a bio is throttled and split after throttling, the bio could be resubmited and enters the throttling again. This will cause part of the bio to be charged multiple times. If the cgroup has an IO limit, the double charge will significantly harm the performance. The bio split becomes quite common after arbitrary bio size change. To fix this, we always set the BIO_THROTTLED flag if a bio is throttled. If the bio is cloned/split, we copy the flag to new bio too to avoid a double charge. However, cloned bio could be directed to a new disk, keeping the flag be a problem. The observation is we always set new disk for the bio in this case, so we can clear the flag in bio_set_dev(). This issue exists for a long time, arbitrary bio size change just makes it worse, so this should go into stable at least since v4.2. V1-> V2: Not add extra field in bio based on discussion with Tejun Cc: Vivek Goyal <vgoyal@redhat.com> Cc: stable@vger.kernel.org Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-12-18block: fix blk_rq_append_bioJens Axboe
Commit caa4b02476e3(blk-map: call blk_queue_bounce from blk_rq_append_bio) moves blk_queue_bounce() into blk_rq_append_bio(), but don't consider the fact that the bounced bio becomes invisible to caller since the parameter type is 'struct bio *'. Make it a pointer to a pointer to a bio, so the caller sees the right bio also after a bounce. Fixes: caa4b02476e3 ("blk-map: call blk_queue_bounce from blk_rq_append_bio") Cc: Christoph Hellwig <hch@lst.de> Reported-by: Michele Ballabio <barra_cuda@katamail.com> (handling failure of blk_rq_append_bio(), only call bio_get() after blk_rq_append_bio() returns OK) Tested-by: Michele Ballabio <barra_cuda@katamail.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-12-18block: don't let passthrough IO go into .make_request_fn()Ming Lei
Commit a8821f3f3("block: Improvements to bounce-buffer handling") tries to make sure that the bio to .make_request_fn won't exceed BIO_MAX_PAGES, but ignores that passthrough I/O can use blk_queue_bounce() too. Especially, passthrough IO may not be sector-aligned, and the check of 'sectors < bio_sectors(*bio_orig)' inside __blk_queue_bounce() may become true even though the max bvec number doesn't exceed BIO_MAX_PAGES, then cause the bio splitted, and the original passthrough bio is submited to generic_make_request(). This patch fixes this issue by checking if the bio is passthrough IO, and use bio_kmalloc() to allocate the cloned passthrough bio. Cc: NeilBrown <neilb@suse.com> Fixes: a8821f3f3("block: Improvements to bounce-buffer handling") Tested-by: Michele Ballabio <barra_cuda@katamail.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-12-06kyber: fix another domain token wait queue hangOmar Sandoval
Commit 8cf466602028 ("kyber: fix hang on domain token wait queue") fixed a hang caused by leaving wait entries on the domain token wait queue after the __sbitmap_queue_get() retry succeeded, making that wait entry a "dud" which won't in turn wake more entries up. However, we can also get a dud entry if kyber_get_domain_token() fails once but is then called again and succeeds. This can happen if the hardware queue is rerun for some other reason, or, more likely, kyber_dispatch_request() tries the same domain twice. The fix is to remove our entry from the wait queue whenever we successfully get a token. The only complication is that we might be on one of many wait queues in the struct sbitmap_queue, but that's easily fixed by remembering which wait queue we were put on. While we're here, only initialize the wait queue entry once instead of on every wait, and use spin_lock_irq() instead of spin_lock_irqsave(), since this is always called from process context with irqs enabled. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-12-01Merge branch 'for-linus' of git://git.kernel.dk/linux-blockLinus Torvalds
Pull block fixes from Jens Axboe: "A selection of fixes/changes that should make it into this series. This contains: - NVMe, two merges, containing: - pci-e, rdma, and fc fixes - Device quirks - Fix for a badblocks leak in null_blk - bcache fix from Rui Hua for a race condition regression where -EINTR was returned to upper layers that didn't expect it. - Regression fix for blktrace for a bug introduced in this series. - blktrace cleanup for cgroup id. - bdi registration error handling. - Small series with cleanups for blk-wbt. - Various little fixes for typos and the like. Nothing earth shattering, most important are the NVMe and bcache fixes" * 'for-linus' of git://git.kernel.dk/linux-block: (34 commits) nvme-pci: fix NULL pointer dereference in nvme_free_host_mem() nvme-rdma: fix memory leak during queue allocation blktrace: fix trace mutex deadlock nvme-rdma: Use mr pool nvme-rdma: Check remotely invalidated rkey matches our expected rkey nvme-rdma: wait for local invalidation before completing a request nvme-rdma: don't complete requests before a send work request has completed nvme-rdma: don't suppress send completions bcache: check return value of register_shrinker bcache: recover data from backing when data is clean bcache: Fix building error on MIPS bcache: add a comment in journal bucket reading nvme-fc: don't use bit masks for set/test_bit() numbers blk-wbt: fix comments typo blk-wbt: move wbt_clear_stat to common place in wbt_done blk-sysfs: remove NULL pointer checking in queue_wb_lat_store blk-wbt: remove duplicated setting in wbt_init nvme-pci: add quirk for delay before CHK RDY for WDC SN200 block: remove useless assignment in bio_split null_blk: fix dev->badblocks leak ...
2017-11-27block: annotate ->poll() instancesAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-11-23blk-wbt: fix comments typoweiping zhang
Signed-off-by: weiping zhang <zhangweiping@didichuxing.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>