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* blk-mq: factor out a helper to iterate all tags for a request_queueChristoph Hellwig2015-10-011-11/+3
| | | | | | | | | And replace the blk_mq_tag_busy_iter with it - the driver use has been replaced with a new helper a while ago, and internal to the block we only need the new version. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: fix racy updates of rq->errorsChristoph Hellwig2015-10-011-6/+6
| | | | | | | | | | | | | | | blk_mq_complete_request may be a no-op if the request has already been completed by others means (e.g. a timeout or cancellation), but currently drivers have to set rq->errors before calling blk_mq_complete_request, which might leave us with the wrong error value. Add an error parameter to blk_mq_complete_request so that we can defer setting rq->errors until we known we won the race to complete the request. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Sagi Grimberg <sagig@mellanox.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: fix deadlock when reading cpu_listAkinobu Mita2015-09-291-0/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | CPU hotplug handling for blk-mq (blk_mq_queue_reinit) acquires all_q_mutex in blk_mq_queue_reinit_notify() and then removes sysfs entries by blk_mq_sysfs_unregister(). Removing sysfs entry needs to be blocked until the active reference of the kernfs_node to be zero. On the other hand, reading blk_mq_hw_sysfs_cpu sysfs entry (e.g. /sys/block/nullb0/mq/0/cpu_list) acquires all_q_mutex in blk_mq_hw_sysfs_cpus_show(). If these happen at the same time, a deadlock can happen. Because one can wait for the active reference to be zero with holding all_q_mutex, and the other tries to acquire all_q_mutex with holding the active reference. The reason that all_q_mutex is acquired in blk_mq_hw_sysfs_cpus_show() is to avoid reading an imcomplete hctx->cpumask. Since reading sysfs entry for blk-mq needs to acquire q->sysfs_lock, we can avoid deadlock and reading an imcomplete hctx->cpumask by protecting q->sysfs_lock while hctx->cpumask is being updated. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Reviewed-by: Ming Lei <tom.leiming@gmail.com> Cc: Ming Lei <tom.leiming@gmail.com> Cc: Wanpeng Li <wanpeng.li@hotmail.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: avoid inserting requests before establishing new mappingAkinobu Mita2015-09-291-14/+45
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Notifier callbacks for CPU_ONLINE action can be run on the other CPU than the CPU which was just onlined. So it is possible for the process running on the just onlined CPU to insert request and run hw queue before establishing new mapping which is done by blk_mq_queue_reinit_notify(). This can cause a problem when the CPU has just been onlined first time since the request queue was initialized. At this time ctx->index_hw for the CPU, which is the index in hctx->ctxs[] for this ctx, is still zero before blk_mq_queue_reinit_notify() is called by notifier callbacks for CPU_ONLINE action. For example, there is a single hw queue (hctx) and two CPU queues (ctx0 for CPU0, and ctx1 for CPU1). Now CPU1 is just onlined and a request is inserted into ctx1->rq_list and set bit0 in pending bitmap as ctx1->index_hw is still zero. And then while running hw queue, flush_busy_ctxs() finds bit0 is set in pending bitmap and tries to retrieve requests in hctx->ctxs[0]->rq_list. But htx->ctxs[0] is a pointer to ctx0, so the request in ctx1->rq_list is ignored. Fix it by ensuring that new mapping is established before onlined cpu starts running. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Reviewed-by: Ming Lei <tom.leiming@gmail.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Ming Lei <tom.leiming@gmail.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: fix q->mq_usage_counter access raceAkinobu Mita2015-09-291-3/+4
| | | | | | | | | | | | | | | | | | CPU hotplug handling for blk-mq (blk_mq_queue_reinit) accesses q->mq_usage_counter while freezing all request queues in all_q_list. On the other hand, q->mq_usage_counter is deinitialized in blk_mq_free_queue() before deleting the queue from all_q_list. So if CPU hotplug event occurs in the window, percpu_ref_kill() is called with q->mq_usage_counter which has already been marked dead, and it triggers warning. Fix it by deleting the queue from all_q_list earlier than destroying q->mq_usage_counter. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Reviewed-by: Ming Lei <tom.leiming@gmail.com> Cc: Ming Lei <tom.leiming@gmail.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: Fix use after of free q->mq_mapAkinobu Mita2015-09-291-5/+3
| | | | | | | | | | | | | | | | | | CPU hotplug handling for blk-mq (blk_mq_queue_reinit) updates q->mq_map by blk_mq_update_queue_map() for all request queues in all_q_list. On the other hand, q->mq_map is released before deleting the queue from all_q_list. So if CPU hotplug event occurs in the window, invalid memory access can happen. Fix it by releasing q->mq_map in blk_mq_release() to make it happen latter than removal from all_q_list. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Suggested-by: Ming Lei <tom.leiming@gmail.com> Reviewed-by: Ming Lei <tom.leiming@gmail.com> Cc: Ming Lei <tom.leiming@gmail.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: fix sysfs registration/unregistration raceAkinobu Mita2015-09-291-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is a race between cpu hotplug handling and adding/deleting gendisk for blk-mq, where both are trying to register and unregister the same sysfs entries. null_add_dev --> blk_mq_init_queue --> blk_mq_init_allocated_queue --> add to 'all_q_list' (*) --> add_disk --> blk_register_queue --> blk_mq_register_disk (++) null_del_dev --> del_gendisk --> blk_unregister_queue --> blk_mq_unregister_disk (--) --> blk_cleanup_queue --> blk_mq_free_queue --> del from 'all_q_list' (*) blk_mq_queue_reinit --> blk_mq_sysfs_unregister (-) --> blk_mq_sysfs_register (+) While the request queue is added to 'all_q_list' (*), blk_mq_queue_reinit() can be called for the queue anytime by CPU hotplug callback. But blk_mq_sysfs_unregister (-) and blk_mq_sysfs_register (+) in blk_mq_queue_reinit must not be called before blk_mq_register_disk (++) and after blk_mq_unregister_disk (--) is finished. Because '/sys/block/*/mq/' is not exists. There has already been BLK_MQ_F_SYSFS_UP flag in hctx->flags which can be used to track these sysfs stuff, but it is only fixing this issue partially. In order to fix it completely, we just need per-queue flag instead of per-hctx flag with appropriate locking. So this introduces q->mq_sysfs_init_done which is properly protected with all_q_mutex. Also, we need to ensure that blk_mq_map_swqueue() is called with all_q_mutex is held. Since hctx->nr_ctx is reset temporarily and updated in blk_mq_map_swqueue(), so we should avoid blk_mq_register_hctx() seeing the temporary hctx->nr_ctx value in CPU hotplug handling or adding/deleting gendisk . Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Reviewed-by: Ming Lei <tom.leiming@gmail.com> Cc: Ming Lei <tom.leiming@gmail.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: avoid setting hctx->tags->cpumask before allocationAkinobu Mita2015-09-291-1/+8
| | | | | | | | | | | | | When unmapped hw queue is remapped after CPU topology is changed, hctx->tags->cpumask has to be set after hctx->tags is setup in blk_mq_map_swqueue(), otherwise it causes null pointer dereference. Fixes: f26cdc8536 ("blk-mq: Shared tag enhancements") Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Keith Busch <keith.busch@intel.com> Cc: Ming Lei <tom.leiming@gmail.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: fix race between timeout and freeing requestMing Lei2015-08-151-15/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Inside timeout handler, blk_mq_tag_to_rq() is called to retrieve the request from one tag. This way is obviously wrong because the request can be freed any time and some fiedds of the request can't be trusted, then kernel oops might be triggered[1]. Currently wrt. blk_mq_tag_to_rq(), the only special case is that the flush request can share same tag with the request cloned from, and the two requests can't be active at the same time, so this patch fixes the above issue by updating tags->rqs[tag] with the active request(either flush rq or the request cloned from) of the tag. Also blk_mq_tag_to_rq() gets much simplified with this patch. Given blk_mq_tag_to_rq() is mainly for drivers and the caller must make sure the request can't be freed, so in bt_for_each() this helper is replaced with tags->rqs[tag]. [1] kernel oops log [ 439.696220] BUG: unable to handle kernel NULL pointer dereference at 0000000000000158^M [ 439.697162] IP: [<ffffffff812d89ba>] blk_mq_tag_to_rq+0x21/0x6e^M [ 439.700653] PGD 7ef765067 PUD 7ef764067 PMD 0 ^M [ 439.700653] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC ^M [ 439.700653] Dumping ftrace buffer:^M [ 439.700653] (ftrace buffer empty)^M [ 439.700653] Modules linked in: nbd ipv6 kvm_intel kvm serio_raw^M [ 439.700653] CPU: 6 PID: 2779 Comm: stress-ng-sigfd Not tainted 4.2.0-rc5-next-20150805+ #265^M [ 439.730500] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011^M [ 439.730500] task: ffff880605308000 ti: ffff88060530c000 task.ti: ffff88060530c000^M [ 439.730500] RIP: 0010:[<ffffffff812d89ba>] [<ffffffff812d89ba>] blk_mq_tag_to_rq+0x21/0x6e^M [ 439.730500] RSP: 0018:ffff880819203da0 EFLAGS: 00010283^M [ 439.730500] RAX: ffff880811b0e000 RBX: ffff8800bb465f00 RCX: 0000000000000002^M [ 439.730500] RDX: 0000000000000000 RSI: 0000000000000202 RDI: 0000000000000000^M [ 439.730500] RBP: ffff880819203db0 R08: 0000000000000002 R09: 0000000000000000^M [ 439.730500] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000202^M [ 439.730500] R13: ffff880814104800 R14: 0000000000000002 R15: ffff880811a2ea00^M [ 439.730500] FS: 00007f165b3f5740(0000) GS:ffff880819200000(0000) knlGS:0000000000000000^M [ 439.730500] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b^M [ 439.730500] CR2: 0000000000000158 CR3: 00000007ef766000 CR4: 00000000000006e0^M [ 439.730500] Stack:^M [ 439.730500] 0000000000000008 ffff8808114eed90 ffff880819203e00 ffffffff812dc104^M [ 439.755663] ffff880819203e40 ffffffff812d9f5e 0000020000000000 ffff8808114eed80^M [ 439.755663] Call Trace:^M [ 439.755663] <IRQ> ^M [ 439.755663] [<ffffffff812dc104>] bt_for_each+0x6e/0xc8^M [ 439.755663] [<ffffffff812d9f5e>] ? blk_mq_rq_timed_out+0x6a/0x6a^M [ 439.755663] [<ffffffff812d9f5e>] ? blk_mq_rq_timed_out+0x6a/0x6a^M [ 439.755663] [<ffffffff812dc1b3>] blk_mq_tag_busy_iter+0x55/0x5e^M [ 439.755663] [<ffffffff812d88b4>] ? blk_mq_bio_to_request+0x38/0x38^M [ 439.755663] [<ffffffff812d8911>] blk_mq_rq_timer+0x5d/0xd4^M [ 439.755663] [<ffffffff810a3e10>] call_timer_fn+0xf7/0x284^M [ 439.755663] [<ffffffff810a3d1e>] ? call_timer_fn+0x5/0x284^M [ 439.755663] [<ffffffff812d88b4>] ? blk_mq_bio_to_request+0x38/0x38^M [ 439.755663] [<ffffffff810a46d6>] run_timer_softirq+0x1ce/0x1f8^M [ 439.755663] [<ffffffff8104c367>] __do_softirq+0x181/0x3a4^M [ 439.755663] [<ffffffff8104c76e>] irq_exit+0x40/0x94^M [ 439.755663] [<ffffffff81031482>] smp_apic_timer_interrupt+0x33/0x3e^M [ 439.755663] [<ffffffff815559a4>] apic_timer_interrupt+0x84/0x90^M [ 439.755663] <EOI> ^M [ 439.755663] [<ffffffff81554350>] ? _raw_spin_unlock_irq+0x32/0x4a^M [ 439.755663] [<ffffffff8106a98b>] finish_task_switch+0xe0/0x163^M [ 439.755663] [<ffffffff8106a94d>] ? finish_task_switch+0xa2/0x163^M [ 439.755663] [<ffffffff81550066>] __schedule+0x469/0x6cd^M [ 439.755663] [<ffffffff8155039b>] schedule+0x82/0x9a^M [ 439.789267] [<ffffffff8119b28b>] signalfd_read+0x186/0x49a^M [ 439.790911] [<ffffffff8106d86a>] ? wake_up_q+0x47/0x47^M [ 439.790911] [<ffffffff811618c2>] __vfs_read+0x28/0x9f^M [ 439.790911] [<ffffffff8117a289>] ? __fget_light+0x4d/0x74^M [ 439.790911] [<ffffffff811620a7>] vfs_read+0x7a/0xc6^M [ 439.790911] [<ffffffff8116292b>] SyS_read+0x49/0x7f^M [ 439.790911] [<ffffffff81554c17>] entry_SYSCALL_64_fastpath+0x12/0x6f^M [ 439.790911] Code: 48 89 e5 e8 a9 b8 e7 ff 5d c3 0f 1f 44 00 00 55 89 f2 48 89 e5 41 54 41 89 f4 53 48 8b 47 60 48 8b 1c d0 48 8b 7b 30 48 8b 53 38 <48> 8b 87 58 01 00 00 48 85 c0 75 09 48 8b 97 88 0c 00 00 eb 10 ^M [ 439.790911] RIP [<ffffffff812d89ba>] blk_mq_tag_to_rq+0x21/0x6e^M [ 439.790911] RSP <ffff880819203da0>^M [ 439.790911] CR2: 0000000000000158^M [ 439.790911] ---[ end trace d40af58949325661 ]---^M Cc: <stable@vger.kernel.org> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* block: make generic_make_request handle arbitrarily sized biosKent Overstreet2015-08-131-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The way the block layer is currently written, it goes to great lengths to avoid having to split bios; upper layer code (such as bio_add_page()) checks what the underlying device can handle and tries to always create bios that don't need to be split. But this approach becomes unwieldy and eventually breaks down with stacked devices and devices with dynamic limits, and it adds a lot of complexity. If the block layer could split bios as needed, we could eliminate a lot of complexity elsewhere - particularly in stacked drivers. Code that creates bios can then create whatever size bios are convenient, and more importantly stacked drivers don't have to deal with both their own bio size limitations and the limitations of the (potentially multiple) devices underneath them. In the future this will let us delete merge_bvec_fn and a bunch of other code. We do this by adding calls to blk_queue_split() to the various make_request functions that need it - a few can already handle arbitrary size bios. Note that we add the call _after_ any call to blk_queue_bounce(); this means that blk_queue_split() and blk_recalc_rq_segments() don't need to be concerned with bouncing affecting segment merging. Some make_request_fn() callbacks were simple enough to audit and verify they don't need blk_queue_split() calls. The skipped ones are: * nfhd_make_request (arch/m68k/emu/nfblock.c) * axon_ram_make_request (arch/powerpc/sysdev/axonram.c) * simdisk_make_request (arch/xtensa/platforms/iss/simdisk.c) * brd_make_request (ramdisk - drivers/block/brd.c) * mtip_submit_request (drivers/block/mtip32xx/mtip32xx.c) * loop_make_request * null_queue_bio * bcache's make_request fns Some others are almost certainly safe to remove now, but will be left for future patches. Cc: Jens Axboe <axboe@kernel.dk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Ming Lei <ming.lei@canonical.com> Cc: Neil Brown <neilb@suse.de> Cc: Alasdair Kergon <agk@redhat.com> Cc: Mike Snitzer <snitzer@redhat.com> Cc: dm-devel@redhat.com Cc: Lars Ellenberg <drbd-dev@lists.linbit.com> Cc: drbd-user@lists.linbit.com Cc: Jiri Kosina <jkosina@suse.cz> Cc: Geoff Levand <geoff@infradead.org> Cc: Jim Paris <jim@jtan.com> Cc: Philip Kelleher <pjk1939@linux.vnet.ibm.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Oleg Drokin <oleg.drokin@intel.com> Cc: Andreas Dilger <andreas.dilger@intel.com> Acked-by: NeilBrown <neilb@suse.de> (for the 'md/md.c' bits) Acked-by: Mike Snitzer <snitzer@redhat.com> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com> [dpark: skip more mq-based drivers, resolve merge conflicts, etc.] Signed-off-by: Dongsu Park <dpark@posteo.net> Signed-off-by: Ming Lin <ming.l@ssi.samsung.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* block: add a bi_error field to struct bioChristoph Hellwig2015-07-291-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | Currently we have two different ways to signal an I/O error on a BIO: (1) by clearing the BIO_UPTODATE flag (2) by returning a Linux errno value to the bi_end_io callback The first one has the drawback of only communicating a single possible error (-EIO), and the second one has the drawback of not beeing persistent when bios are queued up, and are not passed along from child to parent bio in the ever more popular chaining scenario. Having both mechanisms available has the additional drawback of utterly confusing driver authors and introducing bugs where various I/O submitters only deal with one of them, and the others have to add boilerplate code to deal with both kinds of error returns. So add a new bi_error field to store an errno value directly in struct bio and remove the existing mechanisms to clean all this up. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: NeilBrown <neilb@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: set default timeout as 30 secondsMing Lei2015-07-161-1/+1
| | | | | | | | | | It is reasonable to set default timeout of request as 30 seconds instead of 30000 ticks, which may be 300 seconds if HZ is 100, for example, some arm64 based systems may choose 100 HZ. Signed-off-by: Ming Lei <ming.lei@canonical.com> Fixes: c76cbbcf4044 ("blk-mq: put blk_queue_rq_timeout together in blk_mq_init_queue()" Signed-off-by: Jens Axboe <axboe@fb.com>
* Merge branch 'for-4.2/core' of git://git.kernel.dk/linux-blockLinus Torvalds2015-06-251-61/+99
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull core block IO update from Jens Axboe: "Nothing really major in here, mostly a collection of smaller optimizations and cleanups, mixed with various fixes. In more detail, this contains: - Addition of policy specific data to blkcg for block cgroups. From Arianna Avanzini. - Various cleanups around command types from Christoph. - Cleanup of the suspend block I/O path from Christoph. - Plugging updates from Shaohua and Jeff Moyer, for blk-mq. - Eliminating atomic inc/dec of both remaining IO count and reference count in a bio. From me. - Fixes for SG gap and chunk size support for data-less (discards) IO, so we can merge these better. From me. - Small restructuring of blk-mq shared tag support, freeing drivers from iterating hardware queues. From Keith Busch. - A few cfq-iosched tweaks, from Tahsin Erdogan and me. Makes the IOPS mode the default for non-rotational storage" * 'for-4.2/core' of git://git.kernel.dk/linux-block: (35 commits) cfq-iosched: fix other locations where blkcg_to_cfqgd() can return NULL cfq-iosched: fix sysfs oops when attempting to read unconfigured weights cfq-iosched: move group scheduling functions under ifdef cfq-iosched: fix the setting of IOPS mode on SSDs blktrace: Add blktrace.c to BLOCK LAYER in MAINTAINERS file block, cgroup: implement policy-specific per-blkcg data block: Make CFQ default to IOPS mode on SSDs block: add blk_set_queue_dying() to blkdev.h blk-mq: Shared tag enhancements block: don't honor chunk sizes for data-less IO block: only honor SG gap prevention for merges that contain data block: fix returnvar.cocci warnings block, dm: don't copy bios for request clones block: remove management of bi_remaining when restoring original bi_end_io block: replace trylock with mutex_lock in blkdev_reread_part() block: export blkdev_reread_part() and __blkdev_reread_part() suspend: simplify block I/O handling block: collapse bio bit space block: remove unused BIO_RW_BLOCK and BIO_EOF flags block: remove BIO_EOPNOTSUPP ...
| * blk-mq: Shared tag enhancementsKeith Busch2015-06-011-2/+10
| | | | | | | | | | | | | | | | | | | | | | | | Storage controllers may expose multiple block devices that share hardware resources managed by blk-mq. This patch enhances the shared tags so a low-level driver can access the shared resources not tied to the unshared h/w contexts. This way the LLD can dynamically add and delete disks and request queues without having to track all the request_queue hctx's to iterate outstanding tags. Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * block: use an atomic_t for mq_freeze_depthChristoph Hellwig2015-05-191-14/+10
| | | | | | | | | | | | | | | | | | lockdep gets unhappy about the not disabling irqs when using the queue_lock around it. Instead of trying to fix that up just switch to an atomic_t and get rid of the lock. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: make plug work for mutiple disks and queuesShaohua Li2015-05-081-5/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Last patch makes plug work for multiple queue case. However it only works for single disk case, because it assumes only one request in the plug list. If a task is accessing multiple disks, eg MD/DM, the assumption is wrong. Let blk_attempt_plug_merge() record request from the same queue. V2: use NULL parameter in !mq case. Fix a bug. Add comments in blk_attempt_plug_merge to make it less (hopefully) confusion. Cc: Jens Axboe <axboe@fb.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: do limited block plug for multiple queue caseShaohua Li2015-05-081-23/+59
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | plug is still helpful for workload with IO merge, but it can be harmful otherwise especially with multiple hardware queues, as there is (supposed) no lock contention in this case and plug can introduce latency. For multiple queues, we do limited plug, eg plug only if there is request merge. If a request doesn't have merge with following request, the requet will be dispatched immediately. V2: check blk_queue_nomerges() as suggested by Jeff. Cc: Jens Axboe <axboe@fb.com> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: avoid re-initialize request which is failed in direct dispatchShaohua Li2015-05-081-0/+2
| | | | | | | | | | | | | | | | | | | | If we directly issue a request and it fails, we use blk_mq_merge_queue_io(). But we already assigned bio to a request in blk_mq_bio_to_request. blk_mq_merge_queue_io shouldn't run blk_mq_bio_to_request again. Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: fix plugging in blk_sq_make_requestJeff Moyer2015-05-081-22/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The following appears in blk_sq_make_request: /* * If we have multiple hardware queues, just go directly to * one of those for sync IO. */ We clearly don't have multiple hardware queues, here! This comment was introduced with this commit 07068d5b8e (blk-mq: split make request handler for multi and single queue): We want slightly different behavior from them: - On single queue devices, we currently use the per-process plug for deferred IO and for merging. - On multi queue devices, we don't use the per-process plug, but we want to go straight to hardware for SYNC IO. The old code had this: use_plug = !is_flush_fua && ((q->nr_hw_queues == 1) || !is_sync); and that was converted to: use_plug = !is_flush_fua && !is_sync; which is not equivalent. For the single queue case, that second half of the && expression is always true. So, what I think was actually inteded follows (and this more closely matches what is done in blk_queue_bio). V2: delete the 'likely', which should not be a big deal Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* | blk-mq: free hctx->ctxs in queue's release handlerMing Lei2015-06-091-2/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Now blk_cleanup_queue() can be called before calling del_gendisk()[1], inside which hctx->ctxs is touched from blk_mq_unregister_hctx(), but the variable has been freed by blk_cleanup_queue() at that time. So this patch moves freeing of hctx->ctxs into queue's release handler for fixing the oops reported by Stefan. [1], 6cd18e711dd8075 (block: destroy bdi before blockdev is unregistered) Reported-by: Stefan Seyfried <stefan.seyfried@googlemail.com> Cc: NeilBrown <neilb@suse.de> Cc: Christoph Hellwig <hch@lst.de> Cc: stable@vger.kernel.org (v4.0) Signed-off-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* | blk-mq: don't lose requests if a stopped queue restartsShaohua Li2015-05-041-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Normally if driver is busy to dispatch a request the logic is like below: block layer: driver: __blk_mq_run_hw_queue a. blk_mq_stop_hw_queue b. rq add to ctx->dispatch later: 1. blk_mq_start_hw_queue 2. __blk_mq_run_hw_queue But it's possible step 1-2 runs between a and b. And since rq isn't in ctx->dispatch yet, step 2 will not run rq. The rq might get lost if there are no subsequent requests kick in. Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* | blk-mq: fix CPU hotplug handlingMing Lei2015-04-231-21/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | hctx->tags has to be set as NULL in case that it is to be unmapped no matter if set->tags[hctx->queue_num] is NULL or not in blk_mq_map_swqueue() because shared tags can be freed already from another request queue. The same situation has to be considered during handling CPU online too. Unmapped hw queue can be remapped after CPU topo is changed, so we need to allocate tags for the hw queue in blk_mq_map_swqueue(). Then tags allocation for hw queue can be removed in hctx cpu online notifier, and it is reasonable to do that after mapping is updated. Cc: <stable@vger.kernel.org> Reported-by: Dongsu Park <dongsu.park@profitbricks.com> Tested-by: Dongsu Park <dongsu.park@profitbricks.com> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* | blk-mq: fix race between timeout and CPU hotplugMing Lei2015-04-231-3/+13
|/ | | | | | | | | | | | | | | | | Firstly during CPU hotplug, even queue is freezed, timeout handler still may come and access hctx->tags, which may cause use after free, so this patch deactivates timeout handler inside CPU hotplug notifier. Secondly, tags can be shared by more than one queues, so we have to check if the hctx has been unmapped, otherwise still use-after-free on tags can be triggered. Cc: <stable@vger.kernel.org> Reported-by: Dongsu Park <dongsu.park@profitbricks.com> Tested-by: Dongsu Park <dongsu.park@profitbricks.com> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: fix iteration of busy bitmapJens Axboe2015-04-171-3/+3
| | | | | | | | | | Commit 889fa31f00b2 was a bit too eager in reducing the loop count, so we ended up missing queues in some configurations. Ensure that our division rounds up, so that's not the case. Reported-by: Guenter Roeck <linux@roeck-us.net> Fixes: 889fa31f00b2 ("blk-mq: reduce unnecessary software queue looping") Signed-off-by: Jens Axboe <axboe@fb.com>
* Merge branch 'for-4.1/core' of git://git.kernel.dk/linux-blockLinus Torvalds2015-04-161-26/+41
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull block layer core bits from Jens Axboe: "This is the core pull request for 4.1. Not a lot of stuff in here for this round, mostly little fixes or optimizations. This pull request contains: - An optimization that speeds up queue runs on blk-mq, especially for the case where there's a large difference between nr_cpu_ids and the actual mapped software queues on a hardware queue. From Chong Yuan. - Honor node local allocations for requests on legacy devices. From David Rientjes. - Cleanup of blk_mq_rq_to_pdu() from me. - exit_aio() fixup from me, greatly speeding up exiting multiple IO contexts off exit_group(). For my particular test case, fio exit took ~6 seconds. A typical case of both exposing RCU grace periods to user space, and serializing exit of them. - Make blk_mq_queue_enter() honor the gfp mask passed in, so we only wait if __GFP_WAIT is set. From Keith Busch. - blk-mq exports and two added helpers from Mike Snitzer, which will be used by the dm-mq code. - Cleanups of blk-mq queue init from Wei Fang and Xiaoguang Wang" * 'for-4.1/core' of git://git.kernel.dk/linux-block: blk-mq: reduce unnecessary software queue looping aio: fix serial draining in exit_aio() blk-mq: cleanup blk_mq_rq_to_pdu() blk-mq: put blk_queue_rq_timeout together in blk_mq_init_queue() block: remove redundant check about 'set->nr_hw_queues' in blk_mq_alloc_tag_set() block: allocate request memory local to request queue blk-mq: don't wait in blk_mq_queue_enter() if __GFP_WAIT isn't set blk-mq: export blk_mq_run_hw_queues blk-mq: add blk_mq_init_allocated_queue and export blk_mq_register_disk
| * blk-mq: reduce unnecessary software queue loopingChong Yuan2015-04-151-4/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In flush_busy_ctxs() and blk_mq_hctx_has_pending(), regardless of how many ctxs assigned to one hctx, they will all loop hctx->ctx_map.map_size times. Here hctx->ctx_map.map_size is a const ALIGN(nr_cpu_ids, 8) / 8. Especially, flush_busy_ctxs() is in hot code path. And it's unnecessary. Change ->map_size to contain the actually mapped software queues, so we only loop for as many iterations as we have to. And remove cpumask setting and nr_ctx count in blk_mq_init_cpu_queues() since they are all re-done in blk_mq_map_swqueue(). blk_mq_map_swqueue(). Signed-off-by: Chong Yuan <chong.yuan@memblaze.com> Reviewed-by: Wenbo Wang <wenbo.wang@memblaze.com> Updated by me for formatting and commenting. Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: put blk_queue_rq_timeout together in blk_mq_init_queue()Wei Fang2015-03-301-4/+1
| | | | | | | | | | | | | | Don't assign ->rq_timeout twice. Signed-off-by: Wei Fang <fangwei1@huawei.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * block: remove redundant check about 'set->nr_hw_queues' in ↵Xiaoguang Wang2015-03-301-1/+1
| | | | | | | | | | | | | | | | | | | | blk_mq_alloc_tag_set() At the beginning of blk_mq_alloc_tag_set(), we have already checked whether 'set->nr_hw_queues' is zero, so here remove this redundant check. Signed-off-by: Xiaoguang Wang <wangxg.fnst@cn.fujitsu.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: don't wait in blk_mq_queue_enter() if __GFP_WAIT isn't setKeith Busch2015-03-131-3/+6
| | | | | | | | | | | | | | | | | | Return -EBUSY if we're unable to enter a queue immediately when allocating a blk-mq request without __GFP_WAIT. Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: export blk_mq_run_hw_queuesMike Snitzer2015-03-131-4/+4
| | | | | | | | | | | | | | | | | | | | | | Rename blk_mq_run_queues to blk_mq_run_hw_queues, add async argument, and export it. DM's suspend support must be able to run the queue without starting stopped hw queues. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: add blk_mq_init_allocated_queue and export blk_mq_register_diskMike Snitzer2015-03-131-10/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add a variant of blk_mq_init_queue that allows a previously allocated queue to be initialized. blk_mq_init_allocated_queue models blk_init_allocated_queue -- which was also created for DM's use. DM's approach to device creation requires a placeholder request_queue be allocated for use with alloc_dev() but the decision about what type of request_queue will be ultimately created is deferred until all component devices referenced in the DM table are processed to determine the table type (request-based, blk-mq request-based, or bio-based). Also, because of DM's late finalization of the request_queue type the call to blk_mq_register_disk() doesn't happen during alloc_dev(). Must export blk_mq_register_disk() so that DM can backfill the 'mq' dir once the blk-mq queue is fully allocated. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Reviewed-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* | blk-mq: initialize 'struct request' and associated data to zeroLinus Torvalds2015-04-111-3/+1
|/ | | | | | | | | | | | | | | | | | | | | | | Jan Engelhardt reports a strange oops with an invalid ->sense_buffer pointer in scsi_init_cmd_errh() with the blk-mq code. The sense_buffer pointer should have been initialized by the call to scsi_init_request() from blk_mq_init_rq_map(), but there seems to be some non-repeatable memory corruptor. This patch makes sure we initialize the whole struct request allocation (and the associated 'struct scsi_cmnd' for the SCSI case) to zero, by using __GFP_ZERO in the allocation. The old code initialized a couple of individual fields, leaving the rest undefined (although many of them are then initialized in later phases, like blk_mq_rq_ctx_init() etc. It's not entirely clear why this matters, but it's the rigth thing to do regardless, and with 4.0 imminent this is the defensive "let's just make sure everything is initialized properly" patch. Tested-by: Jan Engelhardt <jengelh@inai.de> Acked-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* blk-mq: fix use of incorrect goto label in blk_mq_init_queue error pathMike Snitzer2015-03-131-3/+3
| | | | | | | | | | If percpu_ref_init() fails the allocated q and hctxs must get cleaned up; using 'err_map' doesn't allow that to happen. Signed-off-by: Mike Snitzer <snitzer@redhat.com> Reviewed-by: Ming Lei <ming.lei@canonical.com> Cc: stable@kernel.org Signed-off-by: Jens Axboe <axboe@fb.com>
* Merge branch 'for-3.20/core' of git://git.kernel.dk/linux-blockLinus Torvalds2015-02-121-6/+7
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull core block IO changes from Jens Axboe: "This contains: - A series from Christoph that cleans up and refactors various parts of the REQ_BLOCK_PC handling. Contributions in that series from Dongsu Park and Kent Overstreet as well. - CFQ: - A bug fix for cfq for realtime IO scheduling from Jeff Moyer. - A stable patch fixing a potential crash in CFQ in OOM situations. From Konstantin Khlebnikov. - blk-mq: - Add support for tag allocation policies, from Shaohua. This is a prep patch enabling libata (and other SCSI parts) to use the blk-mq tagging, instead of rolling their own. - Various little tweaks from Keith and Mike, in preparation for DM blk-mq support. - Minor little fixes or tweaks from me. - A double free error fix from Tony Battersby. - The partition 4k issue fixes from Matthew and Boaz. - Add support for zero+unprovision for blkdev_issue_zeroout() from Martin" * 'for-3.20/core' of git://git.kernel.dk/linux-block: (27 commits) block: remove unused function blk_bio_map_sg block: handle the null_mapped flag correctly in blk_rq_map_user_iov blk-mq: fix double-free in error path block: prevent request-to-request merging with gaps if not allowed blk-mq: make blk_mq_run_queues() static dm: fix multipath regression due to initializing wrong request cfq-iosched: handle failure of cfq group allocation block: Quiesce zeroout wrapper block: rewrite and split __bio_copy_iov() block: merge __bio_map_user_iov into bio_map_user_iov block: merge __bio_map_kern into bio_map_kern block: pass iov_iter to the BLOCK_PC mapping functions block: add a helper to free bio bounce buffer pages block: use blk_rq_map_user_iov to implement blk_rq_map_user block: simplify bio_map_kern block: mark blk-mq devices as stackable block: keep established cmd_flags when cloning into a blk-mq request block: add blk-mq support to blk_insert_cloned_request() block: require blk_rq_prep_clone() be given an initialized clone request blk-mq: add tag allocation policy ...
| * blk-mq: make blk_mq_run_queues() staticJens Axboe2015-02-101-5/+4
| | | | | | | | | | | | | | | | We no longer use it outside of blk-mq.c, so we can make it static and stop exporting it. Additionally, kill the 'async' argument, as there's only one used of it. Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: add tag allocation policyShaohua Li2015-01-231-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is the blk-mq part to support tag allocation policy. The default allocation policy isn't changed (though it's not a strict FIFO). The new policy is round-robin for libata. But it's a try-best implementation. If multiple tasks are competing, the tags returned will be mixed (which is unavoidable even with !mq, as requests from different tasks can be mixed in queue) Cc: Jens Axboe <axboe@fb.com> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: export blk_mq_freeze_queue()Jens Axboe2015-01-021-0/+1
| | | | | | | | | | | | | | Commit b4c6a028774b exported the start and unfreeze, but we need the regular blk_mq_freeze_queue() for the loop conversion. Signed-off-by: Jens Axboe <axboe@fb.com>
* | blk-mq: release mq's kobjects in blk_release_queue()Ming Lei2015-01-291-7/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The kobject memory inside blk-mq hctx/ctx shouldn't have been freed before the kobject is released because driver core can access it freely before its release. We can't do that in all ctx/hctx/mq_kobj's release handler because it can be run before blk_cleanup_queue(). Given mq_kobj shouldn't have been introduced, this patch simply moves mq's release into blk_release_queue(). Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* | Revert "blk-mq: fix hctx/ctx kobject use-after-free"Ming Lei2015-01-291-1/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | This reverts commit 76d697d10769048e5721510100bf3a9413a56385. The commit 76d697d10769048 causes general protection fault reported from Bart Van Assche: https://lkml.org/lkml/2015/1/28/334 Reported-by: Bart Van Assche <bart.vanassche@sandisk.com> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* | blk-mq: fix hctx/ctx kobject use-after-freeMing Lei2015-01-201-5/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The kobject memory shouldn't have been freed before the kobject is released because driver core can access it freely before its release. This patch frees hctx in its release callback. For ctx, they share one single per-cpu variable which is associated with the request queue, so free ctx in q->mq_kobj's release handler. Signed-off-by: Sasha Levin <sasha.levin@oracle.com> (fix ctx kobjects) Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* | blk-mq: End unstarted requests on a dying queueKeith Busch2015-01-081-1/+10
| | | | | | | | | | | | | | | | | | | | | | Requests that haven't been started prior to a queue dying can be ended in error without waiting for them to start and time out. Signed-off-by: Keith Busch <keith.busch@intel.com> Added code comment to explain why this is done. Signed-off-by: Jens Axboe <axboe@fb.com>
* | blk-mq: Allow requests to never expireKeith Busch2015-01-081-1/+3
| | | | | | | | | | | | | | | | | | Some types of requests may be started that are not gauranteed to ever complete. This adds a request flag that a driver can use so mark the request as such. Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* | blk-mq: Add helper to abort requeued requestsJens Axboe2015-01-081-0/+20
| | | | | | | | | | | | | | Adds a helper function a driver can use to abort requeued requests in case any are pending when h/w queues are being removed. Signed-off-by: Jens Axboe <axboe@fb.com>
* | blk-mq: Let drivers cancel requeue_workKeith Busch2015-01-081-0/+6
| | | | | | | | | | | | | | | | | | | | Kicking requeued requests will start h/w queues in a work_queue, which may alter the driver's requested state to temporarily stop them. This patch exports a method to cancel the q->requeue_work so a driver can be assured stopped h/w queues won't be started up before it is ready. Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* | blk-mq: Export if requests were startedKeith Busch2015-01-081-0/+6
| | | | | | | | | | | | | | | | Drivers can iterate over all allocated request tags, but their callback needs a way to know if the driver started the request in the first place. Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* | blk-mq: Wake tasks entering queue on dyingKeith Busch2015-01-081-0/+7
| | | | | | | | | | | | | | | | | | | | | | When the queue is set to dying, wake up tasks that are waiting on frozen queue so they realize it is dying and abandon their request. Signed-off-by: Keith Busch <keith.busch@intel.com> Modified by me to add a code comment on the need for the wakeup. Signed-off-by: Jens Axboe <axboe@fb.com>
* | blk-mq: get rid of ->cmd_size in the hardware queueJens Axboe2015-01-071-1/+0
|/ | | | | | | | | We store it in the tag set, we don't need it in the hardware queue. While removing cmd_size, place ->queue_num further down to avoid a hole on 64-bit archs. It's not used in any fast paths, so we can safely move it. Signed-off-by: Jens Axboe <axboe@fb.com>
* block: wake up waiters when a queue is marked dyingJens Axboe2014-12-311-0/+10
| | | | | | | | | | | If it's dying, we can't expect new request to complete and come in an wake up other tasks waiting for requests. So after we have marked it as dying, wake up everybody currently waiting for a request. Once they wake, they will retry their allocation and fail appropriately due to the state of the queue. Tested-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: Export freeze/unfreeze functionsKeith Busch2014-12-201-2/+4
| | | | | | | Let drivers prevent entering a queue that isn't available. Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: Exit queue on alloc failureKeith Busch2014-12-201-1/+3
| | | | | | | Fixes usage counter when a request could not be allocated. Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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