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2019-11-06blkcg: make blkcg_print_stat() print stats only for online blkgsTejun Heo1-5/+8
blkcg_print_stat() iterates blkgs under RCU and doesn't test whether the blkg is online. This can call into pd_stat_fn() on a pd which is still being initialized leading to an oops. The heaviest operation - recursively summing up rwstat counters - is already done while holding the queue_lock. Expand queue_lock to cover the other operations and skip the blkg if it isn't online yet. The online state is protected by both blkcg and queue locks, so this guarantees that only online blkgs are processed. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Roman Gushchin <guro@fb.com> Cc: Josef Bacik <jbacik@fb.com> Fixes: 903d23f0a354 ("blk-cgroup: allow controllers to output their own stats") Cc: stable@vger.kernel.org # v4.19+ Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-15blkcg: Fix multiple bugs in blkcg_activate_policy()Tejun Heo1-18/+51
blkcg_activate_policy() has the following bugs. * cf09a8ee19ad ("blkcg: pass @q and @blkcg into blkcg_pol_alloc_pd_fn()") added @blkcg to ->pd_alloc_fn(); however, blkcg_activate_policy() ends up using pd's allocated for the root blkcg for all preallocations, so ->pd_init_fn() for non-root blkcgs can be passed in pd's which are allocated for the root blkcg. For blk-iocost, this means that ->pd_init_fn() can write beyond the end of the allocated object as it determines the length of the flex array at the end based on the blkcg's nesting level. * Each pd is initialized as they get allocated. If alloc fails, the policy will get freed with pd's initialized on it. * After the above partial failure, the partial pds are not freed. This patch fixes all the above issues by * Restructuring blkcg_activate_policy() so that alloc and init passes are separate. Init takes place only after all allocs succeeded and on failure all allocated pds are freed. * Unifying and fixing the cleanup of the remaining pd_prealloc. Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: cf09a8ee19ad ("blkcg: pass @q and @blkcg into blkcg_pol_alloc_pd_fn()") Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-14bfq: Fix bfq linkage errorPavel Begunkov1-0/+2
Since commit 795fe54c2a828099e ("bfq: Add per-device weight"), bfq uses blkg_conf_prep() and blkg_conf_finish(), which are not exported. So, it causes linkage error if bfq compiled as a module. Fixes: 795fe54c2a828099e ("bfq: Add per-device weight") Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-08-28blkcg: separate blkcg_conf_get_disk() out of blkg_conf_prep()Tejun Heo1-19/+43
Separate out blkcg_conf_get_disk() so that it can be used by blkcg policy interface file input parsers before the policy is actually enabled. This doesn't introduce any functional changes. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-08-28blkcg: make ->cpd_init_fn() optionalTejun Heo1-1/+2
For policies which can do enough initialization from ->cpd_alloc_fn(), make ->cpd_init_fn() optional. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-08-28blkcg: pass @q and @blkcg into blkcg_pol_alloc_pd_fn()Tejun Heo1-3/+3
Instead of @node, pass in @q and @blkcg so that the alloc function has more context. This doesn't cause any behavior change and will be used by io.weight implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-07-16blkcg: allow blkcg_policy->pd_stat() to print non-debug info tooTejun Heo1-6/+3
Currently, ->pd_stat() is called only when moduleparam blkcg_debug_stats is set which prevents it from printing non-debug policy-specific statistics. Let's move debug testing down so that ->pd_stat() can print non-debug stat too. This patch doesn't cause any visible behavior change. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-07-10blkcg: implement REQ_CGROUP_PUNTTejun Heo1-0/+53
When a shared kthread needs to issue a bio for a cgroup, doing so synchronously can lead to priority inversions as the kthread can be trapped waiting for that cgroup. This patch implements REQ_CGROUP_PUNT flag which makes submit_bio() punt the actual issuing to a dedicated per-blkcg work item to avoid such priority inversions. This will be used to fix priority inversions in btrfs compression and should be generally useful as we grow filesystem support for comprehensive IO control. Cc: Chris Mason <clm@fb.com> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-07-10cgroup, blkcg: Prepare some symbols for module and !CONFIG_CGROUP usagesTejun Heo1-0/+1
btrfs is going to use css_put() and wbc helpers to improve cgroup writeback support. Add dummy css_get() definition and export wbc helpers to prepare for module and !CONFIG_CGROUP builds. Reported-by: kbuild test robot <lkp@intel.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-07-10blk-cgroup: turn on psi memstall stuffJosef Bacik1-5/+7
With the psi stuff in place we can use the memstall flag to indicate pressure that happens from throttling. Signed-off-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-06-20blk-cgroup: move struct blkg_stat to bfqChristoph Hellwig1-56/+0
This structure and assorted infrastructure is only used by the bfq I/O scheduler. Move it there instead of bloating the common code. Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-06-20blk-cgroup: introduce a new struct blkg_rwstat_sampleChristoph Hellwig1-20/+19
When sampling the blkcg counts we don't need atomics or per-cpu variables. Introduce a new structure just containing plain u64 counters. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-06-20blk-cgroup: pass blkg_rwstat structures by referenceChristoph Hellwig1-15/+16
Returning a structure generates rather bad code, so switch to passing by reference. Also don't require the structure to be zeroed and add to the 0-initialized counters, but actually set the counters to the calculated value. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-06-20blk-cgroup: factor out a helper to read rwstat counterChristoph Hellwig1-3/+2
Trying to break up the crazy statements to something readable. Also switch to an unsigned counter as it can't ever turn negative. Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-06-15blkcg: blkcg_activate_policy() should initialize ancestors firstTejun Heo1-1/+2
When blkcg_activate_policy() is creating blkg_policy_data for existing blkgs, it did in the wrong order - descendants first. Fix it. None of the existing controllers seem affected by this. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-06-15blkcg: perpcu_ref init/exit should be done from blkg_alloc/free()Tejun Heo1-9/+4
blkg alloc is performed as a separate step from the rest of blkg creation so that GFP_KERNEL allocations can be used when creating blkgs from configuration file writes because otherwise user actions may fail due to failures of opportunistic GFP_NOWAIT allocations. While making blkgs use percpu_ref, 7fcf2b033b84 ("blkcg: change blkg reference counting to use percpu_ref") incorrectly added unconditional opportunistic percpu_ref_init() to blkg_create() breaking this guarantee. This patch moves percpu_ref_init() to blkg_alloc() so makes it use @gfp_mask that blkg_alloc() is called with. Also, percpu_ref_exit() is moved to blkg_free() for consistency. Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: 7fcf2b033b84 ("blkcg: change blkg reference counting to use percpu_ref") Cc: Dennis Zhou <dennis@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-06-15blkcg: update blkcg_print_stat() to handle larger outputsTejun Heo1-2/+6
Depending on the number of devices, blkcg stats can go over the default seqfile buf size. seqfile normally retries with a larger buffer but since the ->pd_stat() addition, blkcg_print_stat() doesn't tell seqfile that overflow has happened and the output gets printed truncated. Fix it by calling seq_commit() w/ -1 on possible overflows. Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: 903d23f0a354 ("blk-cgroup: allow controllers to output their own stats") Cc: stable@vger.kernel.org # v4.19+ Cc: Josef Bacik <jbacik@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-06-05block: Drop unlikely before IS_ERR(_OR_NULL)Kefeng Wang1-1/+1
IS_ERR(_OR_NULL) already contain an 'unlikely' compiler flag, so no need to do that again from its callers. Drop it. Cc: Jens Axboe <axboe@kernel.dk> Cc: linux-block@vger.kernel.org Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-30block: add SPDX tags to block layer files missing licensing informationChristoph Hellwig1-0/+1
Various block layer files do not have any licensing information at all. Add SPDX tags for the default kernel GPLv2 license to those. Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-03-20blkcg: Fix kernel-doc warningsBart Van Assche1-4/+5
Avoid that the following warnings are reported when building with W=1: block/blk-cgroup.c:1755: warning: Function parameter or member 'q' not described in 'blkcg_schedule_throttle' block/blk-cgroup.c:1755: warning: Function parameter or member 'use_memdelay' not described in 'blkcg_schedule_throttle' block/blk-cgroup.c:1779: warning: Function parameter or member 'blkg' not described in 'blkcg_add_delay' block/blk-cgroup.c:1779: warning: Function parameter or member 'now' not described in 'blkcg_add_delay' block/blk-cgroup.c:1779: warning: Function parameter or member 'delta' not described in 'blkcg_add_delay' Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-02-10blk-cgroup: Fix doc related to blkcg_exit_queueMarcos Paulo de Souza1-1/+1
Since 4cf6324b17e9, a portion of function blk_cleanup_queue was moved to a newly created function called blk_exit_queue, including the call of blkcg_exit_queue. So, adjust the documenation according. Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Marcos Paulo de Souza <marcos.souza.org@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-21blkcg: remove unused __blkg_release_rcu()Dennis Zhou1-23/+0
An earlier commit 7fcf2b033b84 ("blkcg: change blkg reference counting to use percpu_ref") moved around the release call from blkg_put() to be a part of the percpu_ref cleanup. Remove the additional unused code which should have been removed earlier. Signed-off-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-19block: save irq state in blkg_lookup_create()Ming Lei1-2/+4
blkg_lookup_create() may be called from pool_map() in which irq state is saved, so we have to do that in blkg_lookup_create(). Otherwise, the following lockdep warning can be triggered: [ 104.258537] ================================ [ 104.259129] WARNING: inconsistent lock state [ 104.259725] 4.20.0-rc6+ #545 Not tainted [ 104.260268] -------------------------------- [ 104.260865] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. [ 104.261727] swapper/49/0 [HC0[0]:SC1[1]:HE0:SE0] takes: [ 104.262444] 00000000db365b5d (&(&pool->lock)->rlock#3){+.?.}, at: thin_endio+0xcf/0x2a3 [dm_thin_pool] [ 104.263747] {SOFTIRQ-ON-W} state was registered at: [ 104.264417] _raw_spin_unlock_irq+0x29/0x4c [ 104.265014] blkg_lookup_create+0xdc/0xe6 [ 104.265609] bio_associate_blkg_from_css+0xd3/0x13f [ 104.266312] bio_associate_blkg+0x15a/0x1bb [ 104.266913] pool_map+0xe8/0x103 [dm_thin_pool] [ 104.267572] __map_bio+0x98/0x29c [dm_mod] [ 104.268162] __split_and_process_non_flush+0x29e/0x306 [dm_mod] [ 104.269003] __split_and_process_bio+0x16a/0x25b [dm_mod] [ 104.269971] __dm_make_request.isra.14+0xdc/0x124 [dm_mod] [ 104.270973] generic_make_request+0x3f5/0x68b [ 104.271676] process_prepared_mapping+0x166/0x1ef [dm_thin_pool] [ 104.272531] schedule_zero+0x239/0x273 [dm_thin_pool] [ 104.273245] process_cell+0x60c/0x6f1 [dm_thin_pool] [ 104.273967] do_worker+0x60c/0xca8 [dm_thin_pool] [ 104.274635] process_one_work+0x4eb/0x834 [ 104.275203] worker_thread+0x318/0x484 [ 104.275740] kthread+0x1d1/0x1e1 [ 104.276203] ret_from_fork+0x3a/0x50 [ 104.276714] irq event stamp: 170003 [ 104.277201] hardirqs last enabled at (170002): [<ffffffff81bcc33e>] _raw_spin_unlock_irqrestore+0x44/0x6b [ 104.278535] hardirqs last disabled at (170003): [<ffffffff81bcc1ad>] _raw_spin_lock_irqsave+0x20/0x55 [ 104.280273] softirqs last enabled at (169978): [<ffffffff810d13d4>] irq_enter+0x4c/0x73 [ 104.281617] softirqs last disabled at (169979): [<ffffffff810d1479>] irq_exit+0x7e/0x11d [ 104.282744] [ 104.282744] other info that might help us debug this: [ 104.283640] Possible unsafe locking scenario: [ 104.283640] [ 104.284452] CPU0 [ 104.284803] ---- [ 104.285150] lock(&(&pool->lock)->rlock#3); [ 104.285762] <Interrupt> [ 104.286130] lock(&(&pool->lock)->rlock#3); [ 104.286750] [ 104.286750] *** DEADLOCK *** [ 104.286750] [ 104.287564] no locks held by swapper/49/0. [ 104.288129] [ 104.288129] stack backtrace: [ 104.288738] CPU: 49 PID: 0 Comm: swapper/49 Not tainted 4.20.0-rc6+ #545 [ 104.289700] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-2.fc27 04/01/2014 [ 104.290858] Call Trace: [ 104.291204] <IRQ> [ 104.291502] dump_stack+0x9a/0xe6 [ 104.291968] mark_lock+0x56c/0x7a6 [ 104.292442] ? check_usage_backwards+0x209/0x209 [ 104.293086] __lock_acquire+0x400/0x15bf [ 104.293662] ? check_chain_key+0x150/0x1aa [ 104.294236] lock_acquire+0x1a6/0x1e3 [ 104.294768] ? thin_endio+0xcf/0x2a3 [dm_thin_pool] [ 104.295444] ? _raw_spin_unlock_irqrestore+0x44/0x6b [ 104.296143] ? process_prepared_discard_fail+0x36/0x36 [dm_thin_pool] [ 104.297031] _raw_spin_lock_irqsave+0x46/0x55 [ 104.297659] ? thin_endio+0xcf/0x2a3 [dm_thin_pool] [ 104.298335] thin_endio+0xcf/0x2a3 [dm_thin_pool] [ 104.298997] ? process_prepared_discard_fail+0x36/0x36 [dm_thin_pool] [ 104.299886] ? check_flags+0x20a/0x20a [ 104.300408] ? lock_acquire+0x1a6/0x1e3 [ 104.300954] ? process_prepared_discard_fail+0x36/0x36 [dm_thin_pool] [ 104.301865] clone_endio+0x1bb/0x22d [dm_mod] [ 104.302491] ? disable_write_zeroes+0x20/0x20 [dm_mod] [ 104.303200] ? bio_disassociate_blkg+0xc6/0x15f [ 104.303836] ? bio_endio+0x2b2/0x2da [ 104.304349] clone_endio+0x1f3/0x22d [dm_mod] [ 104.304978] ? disable_write_zeroes+0x20/0x20 [dm_mod] [ 104.305709] ? bio_disassociate_blkg+0xc6/0x15f [ 104.306333] ? bio_endio+0x2b2/0x2da [ 104.306853] clone_endio+0x1f3/0x22d [dm_mod] [ 104.307476] ? disable_write_zeroes+0x20/0x20 [dm_mod] [ 104.308185] ? bio_disassociate_blkg+0xc6/0x15f [ 104.308817] ? bio_endio+0x2b2/0x2da [ 104.309319] blk_update_request+0x2de/0x4cc [ 104.309927] blk_mq_end_request+0x2a/0x183 [ 104.310498] blk_done_softirq+0x16a/0x1a6 [ 104.311051] ? blk_softirq_cpu_dead+0xe2/0xe2 [ 104.311653] ? __lock_is_held+0x2a/0x87 [ 104.312186] __do_softirq+0x250/0x4e8 [ 104.312705] irq_exit+0x7e/0x11d [ 104.313157] call_function_single_interrupt+0xf/0x20 [ 104.313860] </IRQ> [ 104.314163] RIP: 0010:native_safe_halt+0x2/0x3 [ 104.314792] Code: 63 02 df f0 83 44 24 fc 00 48 89 df e8 cc 3f 7a ff 48 8b 03 a8 08 74 0b 65 81 25 9d 31 45 7e ff ff ff 7f 5b 5d 41 5c c3 fb f4 <c3> f4 c3 0f 1f 44 00 00 41 56 41 55 41 54 55 53 e8 a2 0d 5c ff e8 [ 104.317339] RSP: 0018:ffff888106c9fdc0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff04 [ 104.318390] RAX: 1ffff11020d92100 RBX: 0000000000000000 RCX: ffffffff81159ac7 [ 104.319366] RDX: 1ffffffff05d5e69 RSI: 0000000000000007 RDI: ffff888106c90d1c [ 104.320339] RBP: 0000000000000000 R08: dffffc0000000000 R09: 0000000000000001 [ 104.321313] R10: ffffed1025d57ba0 R11: ffffed1025d57b9f R12: 1ffff11020d93fbf [ 104.322328] R13: 0000000000000031 R14: ffff888106c90040 R15: 0000000000000000 [ 104.323307] ? lockdep_hardirqs_on+0x26b/0x278 [ 104.323927] default_idle+0xd9/0x1a8 [ 104.324427] do_idle+0x162/0x2b2 [ 104.324891] ? arch_cpu_idle_exit+0x28/0x28 [ 104.325467] ? mark_held_locks+0x28/0x7f [ 104.326031] ? _raw_spin_unlock_irqrestore+0x44/0x6b [ 104.326719] cpu_startup_entry+0x1d/0x1f [ 104.327261] start_secondary+0x2cb/0x308 [ 104.327806] ? set_cpu_sibling_map+0x8a3/0x8a3 [ 104.328421] secondary_startup_64+0xa4/0xb0 Fixes: b978962ad4f7f9 ("blkcg: update blkg_lookup_create() to do locking") Cc: Mike Snitzer <snitzer@redhat.com> Cc: Dennis Zhou <dennis@kernel.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-12blkcg: handle dying request_queue when associating a blkgDennis Zhou1-0/+6
Between v3 [1] and v4 [2] of the blkg association series, the association point moved from generic_make_request_checks(), which is called after the request enters the queue, to bio_set_dev(), which is when the bio is formed before submit_bio(). When the request_queue goes away, the blkgs supporting the request_queue are destroyed and then the q->root_blkg is set to %NULL. This patch adds a %NULL check to blkg_tryget_closest() to prevent the NPE caused by the above. It also adds a guard to see if the request_queue is dying when creating a blkg to prevent creating a blkg for a dead request_queue. [1] https://lore.kernel.org/lkml/20180911184137.35897-1-dennisszhou@gmail.com/ [2] https://lore.kernel.org/lkml/20181126211946.77067-1-dennis@kernel.org/ Fixes: 5cdf2e3fea5e ("blkcg: associate blkg when associating a device") Reported-and-tested-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-07blkcg: rename blkg_try_get() to blkg_tryget()Dennis Zhou1-2/+1
blkg reference counting now uses percpu_ref rather than atomic_t. Let's make this consistent with css_tryget. This renames blkg_try_get to blkg_tryget and now returns a bool rather than the blkg or %NULL. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-07blkcg: change blkg reference counting to use percpu_refDennis Zhou1-2/+39
Every bio is now associated with a blkg putting blkg_get, blkg_try_get, and blkg_put on the hot path. Switch over the refcnt in blkg to use percpu_ref. Signed-off-by: Dennis Zhou <dennis@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-07blkcg: convert blkg_lookup_create() to find closest blkgDennis Zhou1-7/+16
There are several scenarios where blkg_lookup_create() can fail such as the blkcg dying, request_queue is dying, or simply being OOM. Most handle this by simply falling back to the q->root_blkg and calling it a day. This patch implements the notion of closest blkg. During blkg_lookup_create(), if it fails to create, return the closest blkg found or the q->root_blkg. blkg_try_get_closest() is introduced and used during association so a bio is always attached to a blkg. Signed-off-by: Dennis Zhou <dennis@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-07blkcg: update blkg_lookup_create() to do lockingDennis Zhou1-3/+25
To know when to create a blkg, the general pattern is to do a blkg_lookup() and if that fails, lock and do the lookup again, and if that fails finally create. It doesn't make much sense for everyone who wants to do creation to write this themselves. This changes blkg_lookup_create() to do locking and implement this pattern. The old blkg_lookup_create() is renamed to __blkg_lookup_create(). If a call site wants to do its own error handling or already owns the queue lock, they can use __blkg_lookup_create(). This will be used in upcoming patches. Signed-off-by: Dennis Zhou <dennis@kernel.org> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-16block: add queue_is_mq() helperJens Axboe1-4/+4
Various spots check for q->mq_ops being non-NULL, but provide a helper to do this instead. Where the ->mq_ops != NULL check is redundant, remove it. Since mq == rq-based now that legacy is gone, get rid of the queue_is_rq_based() and just use queue_is_mq() everywhere. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-15block: remove the queue_lock indirectionChristoph Hellwig1-31/+31
With the legacy request path gone there is no good reason to keep queue_lock as a pointer, we can always use the embedded lock now. Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Fixed floppy and blk-cgroup missing conversions and half done edits. Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-15blk-cgroup: move locking into blkg_destroy_allChristoph Hellwig1-7/+2
Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-15blk-cgroup: consolidate error handling in blkcg_init_queueChristoph Hellwig1-12/+10
Use a goto label to merge two identical pieces of error handling code. Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-15block: remove a few unused exportsChristoph Hellwig1-6/+0
Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-15block: remove QUEUE_FLAG_BYPASS and ->bypassChristoph Hellwig1-15/+0
Unused since the removal of the legacy request code. Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07block: remove request_list codeJens Axboe1-47/+0
It's now dead code, nobody uses it. Reviewed-by: Hannes Reinecke <hare@suse.com> Tested-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07blk-cgroup: remove legacy queue bypassingJens Axboe1-8/+0
We only support mq devices now. Reviewed-by: Hannes Reinecke <hare@suse.com> Tested-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-01blkcg: revert blkcg cleanups seriesDennis Zhou1-85/+38
This reverts a series committed earlier due to null pointer exception bug report in [1]. It seems there are edge case interactions that I did not consider and will need some time to understand what causes the adverse interactions. The original series can be found in [2] with a follow up series in [3]. [1] https://www.spinics.net/lists/cgroups/msg20719.html [2] https://lore.kernel.org/lkml/20180911184137.35897-1-dennisszhou@gmail.com/ [3] https://lore.kernel.org/lkml/20181020185612.51587-1-dennis@kernel.org/ This reverts the following commits: d459d853c2ed, b2c3fa546705, 101246ec02b5, b3b9f24f5fcc, e2b0989954ae, f0fcb3ec89f3, c839e7a03f92, bdc2491708c4, 74b7c02a9bc1, 5bf9a1f3b4ef, a7b39b4e961c, 07b05bcc3213, 49f4c2dc2b50, 27e6fa996c53 Signed-off-by: Dennis Zhou <dennis@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-10-01Merge tag 'v4.19-rc6' into for-4.20/blockJens Axboe1-1/+3
Merge -rc6 in, for two reasons: 1) Resolve a trivial conflict in the blk-mq-tag.c documentation 2) A few important regression fixes went into upstream directly, so they aren't in the 4.20 branch. Signed-off-by: Jens Axboe <axboe@kernel.dk> * tag 'v4.19-rc6': (780 commits) Linux 4.19-rc6 MAINTAINERS: fix reference to moved drivers/{misc => auxdisplay}/panel.c cpufreq: qcom-kryo: Fix section annotations perf/core: Add sanity check to deal with pinned event failure xen/blkfront: correct purging of persistent grants Revert "xen/blkfront: When purging persistent grants, keep them in the buffer" selftests/powerpc: Fix Makefiles for headers_install change blk-mq: I/O and timer unplugs are inverted in blktrace dax: Fix deadlock in dax_lock_mapping_entry() x86/boot: Fix kexec booting failure in the SEV bit detection code bcache: add separate workqueue for journal_write to avoid deadlock drm/amd/display: Fix Edid emulation for linux drm/amd/display: Fix Vega10 lightup on S3 resume drm/amdgpu: Fix vce work queue was not cancelled when suspend Revert "drm/panel: Add device_link from panel device to DRM device" xen/blkfront: When purging persistent grants, keep them in the buffer clocksource/drivers/timer-atmel-pit: Properly handle error cases block: fix deadline elevator drain for zoned block devices ACPI / hotplug / PCI: Don't scan for non-hotplug bridges if slot is not bridge drm/syncobj: Don't leak fences when WAIT_FOR_SUBMIT is set ... Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21blkcg: rename blkg_try_get to blkg_trygetDennis Zhou (Facebook)1-2/+1
blkg reference counting now uses percpu_ref rather than atomic_t. Let's make this consistent with css_tryget. This renames blkg_try_get to blkg_tryget and now returns a bool rather than the blkg or NULL. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21blkcg: change blkg reference counting to use percpu_refDennis Zhou (Facebook)1-25/+39
Now that every bio is associated with a blkg, this puts the use of blkg_get, blkg_try_get, and blkg_put on the hot path. This switches over the refcnt in blkg to use percpu_ref. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21blkcg: convert blkg_lookup_create to find closest blkgDennis Zhou (Facebook)1-8/+17
There are several scenarios where blkg_lookup_create can fail. Examples include the blkcg dying, request_queue is dying, or simply being OOM. At the end of the day, most handle this by simply falling back to the q->root_blkg and calling it a day. This patch implements the notion of closest blkg. During blkg_lookup_create, if it fails to create, return the closest blkg found or the q->root_blkg. blkg_try_get_closest is introduced and used during association so a bio is always attached to a blkg. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-21blkcg: update blkg_lookup_create to do lockingDennis Zhou (Facebook)1-3/+28
To know when to create a blkg, the general pattern is to do a blkg_lookup and if that fails, lock and then do a lookup again and if that fails finally create. It doesn't make much sense for everyone who wants to do creation to write this themselves. This changes blkg_lookup_create to do locking and implement this pattern. The old blkg_lookup_create is renamed to __blkg_lookup_create. If a call site wants to do its own error handling or already owns the queue lock, they can use __blkg_lookup_create. This will be used in upcoming patches. Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-09-11blk-cgroup: increase number of supported policiesJens Axboe1-1/+3
After merging the iolatency policy, we potentially now have 4 policies being registered, but only support 3. This causes one of them to fail loading. Takashi reports that BFQ no longer works for him, because it fails to load due to policy registration failure. Bump to 5 policies, and also add a warning for when we have exceeded the global amount. If we have to touch this again, we should switch to a dynamic scheme instead. Reported-by: Takashi Iwai <tiwai@suse.de> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Tested-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-31blkcg: delay blkg destruction until after writeback has finishedDennis Zhou (Facebook)1-8/+45
Currently, blkcg destruction relies on a sequence of events: 1. Destruction starts. blkcg_css_offline() is called and blkgs release their reference to the blkcg. This immediately destroys the cgwbs (writeback). 2. With blkgs giving up their reference, the blkcg ref count should become zero and eventually call blkcg_css_free() which finally frees the blkcg. Jiufei Xue reported that there is a race between blkcg_bio_issue_check() and cgroup_rmdir(). To remedy this, blkg destruction becomes contingent on the completion of all writeback associated with the blkcg. A count of the number of cgwbs is maintained and once that goes to zero, blkg destruction can follow. This should prevent premature blkg destruction related to writeback. The new process for blkcg cleanup is as follows: 1. Destruction starts. blkcg_css_offline() is called which offlines writeback. Blkg destruction is delayed on the cgwb_refcnt count to avoid punting potentially large amounts of outstanding writeback to root while maintaining any ongoing policies. Here, the base cgwb_refcnt is put back. 2. When the cgwb_refcnt becomes zero, blkcg_destroy_blkgs() is called and handles destruction of blkgs. This is where the css reference held by each blkg is released. 3. Once the blkcg ref count goes to zero, blkcg_css_free() is called. This finally frees the blkg. It seems in the past blk-throttle didn't do the most understandable things with taking data from a blkg while associating with current. So, the simplification and unification of what blk-throttle is doing caused this. Fixes: 08e18eab0c579 ("block: add bi_blkg to the bio for cgroups") Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Cc: Jiufei Xue <jiufei.xue@linux.alibaba.com> Cc: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Tejun Heo <tj@kernel.org> Cc: Josef Bacik <josef@toxicpanda.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-31Revert "blk-throttle: fix race between blkcg_bio_issue_check() and cgroup_rmdir()"Dennis Zhou (Facebook)1-62/+16
This reverts commit 4c6994806f708559c2812b73501406e21ae5dcd0. Destroying blkgs is tricky because of the nature of the relationship. A blkg should go away when either a blkcg or a request_queue goes away. However, blkg's pin the blkcg to ensure they remain valid. To break this cycle, when a blkcg is offlined, blkgs put back their css ref. This eventually lets css_free() get called which frees the blkcg. The above commit (4c6994806f70) breaks this order of events by trying to destroy blkgs in css_free(). As the blkgs still hold references to the blkcg, css_free() is never called. The race between blkcg_bio_issue_check() and cgroup_rmdir() will be addressed in the following patch by delaying destruction of a blkg until all writeback associated with the blkcg has been finished. Fixes: 4c6994806f70 ("blk-throttle: fix race between blkcg_bio_issue_check() and cgroup_rmdir()") Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Cc: Jiufei Xue <jiufei.xue@linux.alibaba.com> Cc: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-01blk-cgroup: hold the queue ref during throttlingJosef Bacik1-1/+1
The blkg lifetime is protected by the queue lifetime, so we need to put the queue _after_ we're done using the blkg. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-18blkcg: Track DISCARD statistics and output them in cgroup io.statTejun Heo1-4/+9
Add tracking of REQ_OP_DISCARD ios to the per-cgroup io.stat. Two fields, dbytes and dios, to respectively count the total bytes and number of discards are added. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Andy Newell <newella@fb.com> Cc: Michael Callahan <michaelcallahan@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09block: introduce blk-iolatency io controllerJosef Bacik1-0/+8
Current IO controllers for the block layer are less than ideal for our use case. The io.max controller is great at hard limiting, but it is not work conserving. This patch introduces io.latency. You provide a latency target for your group and we monitor the io in short windows to make sure we are not exceeding those latency targets. This makes use of the rq-qos infrastructure and works much like the wbt stuff. There are a few differences from wbt - It's bio based, so the latency covers the whole block layer in addition to the actual io. - We will throttle all IO types that comes in here if we need to. - We use the mean latency over the 100ms window. This is because writes can be particularly fast, which could give us a false sense of the impact of other workloads on our protected workload. - By default there's no throttling, we set the queue_depth to INT_MAX so that we can have as many outstanding bio's as we're allowed to. Only at throttle time do we pay attention to the actual queue depth. - We backcharge cgroups for root cg issued IO and induce artificial delays in order to deal with cases like metadata only or swap heavy workloads. In testing this has worked out relatively well. Protected workloads will throttle noisy workloads down to 1 io at time if they are doing normal IO on their own, or induce up to a 1 second delay per syscall if they are doing a lot of root issued IO (metadata/swap IO). Our testing has revolved mostly around our production web servers where we have hhvm (the web server application) in a protected group and everything else in another group. We see slightly higher requests per second (RPS) on the test tier vs the control tier, and much more stable RPS across all machines in the test tier vs the control tier. Another test we run is a slow memory allocator in the unprotected group. Before this would eventually push us into swap and cause the whole box to die and not recover at all. With these patches we see slight RPS drops (usually 10-15%) before the memory consumer is properly killed and things recover within seconds. Signed-off-by: Josef Bacik <jbacik@fb.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09blkcg: add generic throttling mechanismJosef Bacik1-0/+220
Since IO can be issued from literally anywhere it's almost impossible to do throttling without having some sort of adverse effect somewhere else in the system because of locking or other dependencies. The best way to solve this is to do the throttling when we know we aren't holding any other kernel resources. Do this by tracking throttling in a per-blkg basis, and if we require throttling flag the task that it needs to check before it returns to user space and possibly sleep there. This is to address the case where a process is doing work that is generating IO that can't be throttled, whether that is directly with a lot of REQ_META IO, or indirectly by allocating so much memory that it is swamping the disk with REQ_SWAP. We can't use task_add_work as we don't want to induce a memory allocation in the IO path, so simply saving the request queue in the task and flagging it to do the notify_resume thing achieves the same result without the overhead of a memory allocation. Signed-off-by: Josef Bacik <jbacik@fb.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09blk-cgroup: allow controllers to output their own statsJosef Bacik1-3/+44
blk-iolatency has a few stats that it would like to print out, and instead of adding a bunch of crap to the generic code just provide a helper so that controllers can add stuff to the stat line if they want to. Hide it behind a boot option since it changes the output of io.stat from normal, and these stats are only interesting to developers. Signed-off-by: Josef Bacik <jbacik@fb.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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