Commit Graph

307 Commits

Author SHA1 Message Date
Tejun Heo
4308a434e5 blkcg: don't offline parent blkcg first
blkcg->cgwb_refcnt is used to delay blkcg offlining so that blkgs
don't get offlined while there are active cgwbs on them.  However, it
ends up making offlining unordered sometimes causing parents to be
offlined before children.

Let's fix this by making child blkcgs pin the parents' online states.

Note that pin/unpin names are chosen over get/put intentionally
because css uses get/put online for something different.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-04-01 14:56:44 -06:00
Tejun Heo
d866dbf617 blkcg: rename blkcg->cgwb_refcnt to ->online_pin and always use it
blkcg->cgwb_refcnt is used to delay blkcg offlining so that blkgs
don't get offlined while there are active cgwbs on them.  However, it
ends up making offlining unordered sometimes causing parents to be
offlined before children.

To fix it, we want child blkcgs to pin the parents' online states
turning the refcnt into a more generic online pinning mechanism.

In prepartion,

* blkcg->cgwb_refcnt -> blkcg->online_pin
* blkcg_cgwb_get/put() -> blkcg_pin/unpin_online()
* Take them out of CONFIG_CGROUP_WRITEBACK

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-04-01 14:56:42 -06:00
Christoph Hellwig
3d745ea5b0 block: simplify queue allocation
Current make_request based drivers use either blk_alloc_queue_node or
blk_alloc_queue to allocate a queue, and then set up the make_request_fn
function pointer and a few parameters using the blk_queue_make_request
helper.  Simplify this by passing the make_request pointer to
blk_alloc_queue, and while at it merge the _node variant into the main
helper by always passing a node_id, and remove the superfluous gfp_mask
parameter.  A lower-level __blk_alloc_queue is kept for the blk-mq case.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-03-27 10:23:43 -06:00
Guoqing Jiang
5addeae1be blk-cgroup: remove blkcg_drain_queue
Since blk_drain_queue had already been removed, so this function
is not needed anymore.

Signed-off-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-12-12 09:26:55 -07:00
Tejun Heo
1d156646e0 blk-cgroup: separate out blkg_rwstat under CONFIG_BLK_CGROUP_RWSTAT
blkg_rwstat is now only used by bfq-iosched and blk-throtl when on
cgroup1.  Let's move it into its own files and gate it behind a config
option.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-11-07 12:28:13 -07:00
Tejun Heo
f733164829 blk-cgroup: reimplement basic IO stats using cgroup rstat
blk-cgroup has been using blkg_rwstat to track basic IO stats.
Unfortunately, reading recursive stats scales badly as itinvolves
walking all descendants.  On systems with a huge number of cgroups
(dead or alive), this can lead to substantial CPU cost when reading IO
stats.

This patch reimplements basic IO stats using cgroup rstat which uses
more memory but makes recursive stat reading O(# descendants which
have been active since last reading) instead of O(# descendants).

* blk-cgroup core no longer uses sync/async stats.  Introduce new stat
  enums - BLKG_IOSTAT_{READ|WRITE|DISCARD}.

* Add blkg_iostat[_set] which encapsulates byte and io stats, last
  values for propagation delta calculation and u64_stats_sync for
  correctness on 32bit archs.

* Update the new percpu stat counters directly and implement
  blkcg_rstat_flush() to implement propagation.

* blkg_print_stat() can now bring the stats up to date by calling
  cgroup_rstat_flush() and print them instead of directly summing up
  all descendants.

* It now allocates 96 bytes per cpu.  It used to be 40 bytes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Dan Schatzberg <dschatzberg@fb.com>
Cc: Daniel Xu <dlxu@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-11-07 12:28:13 -07:00
Tejun Heo
8a80d5d663 blk-cgroup: remove now unused blkg_print_stat_{bytes|ios}_recursive()
These don't have users anymore.  Remove them.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-11-07 12:28:13 -07:00
Tejun Heo
b0814361a2 blkcg: make blkcg_print_stat() print stats only for online blkgs
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: 903d23f0a3 ("blk-cgroup: allow controllers to output their own stats")
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-11-06 17:08:38 -07:00
Tejun Heo
9d179b8654 blkcg: Fix multiple bugs in blkcg_activate_policy()
blkcg_activate_policy() has the following bugs.

* cf09a8ee19 ("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: cf09a8ee19 ("blkcg: pass @q and @blkcg into blkcg_pol_alloc_pd_fn()")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-15 10:13:00 -06:00
Pavel Begunkov
89f3b6d62f bfq: Fix bfq linkage error
Since commit 795fe54c2a ("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: 795fe54c2a ("bfq: Add per-device weight")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-09-14 11:33:43 -06:00
Tejun Heo
015d254cb0 blkcg: separate blkcg_conf_get_disk() out of blkg_conf_prep()
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>
2019-08-28 21:17:04 -06:00
Tejun Heo
86a5bba5c2 blkcg: make ->cpd_init_fn() optional
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>
2019-08-28 21:17:03 -06:00
Tejun Heo
cf09a8ee19 blkcg: pass @q and @blkcg into blkcg_pol_alloc_pd_fn()
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>
2019-08-28 21:17:01 -06:00
Tejun Heo
07b0fdecb2 blkcg: allow blkcg_policy->pd_stat() to print non-debug info too
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>
2019-07-16 10:06:39 -06:00
Tejun Heo
d3f77dfdc7 blkcg: implement REQ_CGROUP_PUNT
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>
2019-07-10 09:00:57 -06:00
Tejun Heo
9b0eb69b75 cgroup, blkcg: Prepare some symbols for module and !CONFIG_CGROUP usages
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>
2019-07-10 09:00:57 -06:00
Josef Bacik
fd112c7465 blk-cgroup: turn on psi memstall stuff
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>
2019-07-10 09:00:57 -06:00
Christoph Hellwig
c0ce79dca5 blk-cgroup: move struct blkg_stat to bfq
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>
2019-06-20 10:32:34 -06:00
Christoph Hellwig
7af6fd9112 blk-cgroup: introduce a new struct blkg_rwstat_sample
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>
2019-06-20 10:32:34 -06:00
Christoph Hellwig
5d0b6e48cb blk-cgroup: pass blkg_rwstat structures by reference
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>
2019-06-20 10:32:34 -06:00
Christoph Hellwig
239eeb0857 blk-cgroup: factor out a helper to read rwstat counter
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>
2019-06-20 10:32:34 -06:00
Tejun Heo
71c814077d blkcg: blkcg_activate_policy() should initialize ancestors first
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>
2019-06-15 10:39:40 -06:00
Tejun Heo
ef069b97fe blkcg: perpcu_ref init/exit should be done from blkg_alloc/free()
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, 7fcf2b033b ("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: 7fcf2b033b ("blkcg: change blkg reference counting to use percpu_ref")
Cc: Dennis Zhou <dennis@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-06-15 10:39:39 -06:00
Tejun Heo
f539da82f2 blkcg: update blkcg_print_stat() to handle larger outputs
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: 903d23f0a3 ("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>
2019-06-15 10:39:37 -06:00
Kefeng Wang
98d669b491 block: Drop unlikely before IS_ERR(_OR_NULL)
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>
2019-06-05 08:22:24 -06:00
Christoph Hellwig
3dcf60bcb6 block: add SPDX tags to block layer files missing licensing information
Various block layer files do not have any licensing information at all.
Add SPDX tags for the default kernel GPLv2 license to those.

Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-30 16:12:03 -06:00
Bart Van Assche
537d71b3f7 blkcg: Fix kernel-doc warnings
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>
2019-03-20 14:39:09 -06:00
Marcos Paulo de Souza
7585d5082e blk-cgroup: Fix doc related to blkcg_exit_queue
Since 4cf6324b17, 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>
2019-02-10 08:24:08 -07:00
Dennis Zhou
6b4505352e blkcg: remove unused __blkg_release_rcu()
An earlier commit 7fcf2b033b ("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>
2018-12-21 08:47:58 -07:00
Ming Lei
3a762de55b block: save irq state in blkg_lookup_create()
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: b978962ad4 ("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>
2018-12-19 09:35:45 -07:00
Dennis Zhou
0273ac349f blkcg: handle dying request_queue when associating a blkg
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: 5cdf2e3fea ("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>
2018-12-12 17:43:33 -07:00
Dennis Zhou
7754f669ff blkcg: rename blkg_try_get() to blkg_tryget()
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>
2018-12-07 22:26:38 -07:00
Dennis Zhou
7fcf2b033b blkcg: change blkg reference counting to use percpu_ref
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>
2018-12-07 22:26:38 -07:00
Dennis Zhou
beea9da07d blkcg: convert blkg_lookup_create() to find closest blkg
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>
2018-12-07 22:26:36 -07:00
Dennis Zhou
b978962ad4 blkcg: update blkg_lookup_create() to do locking
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>
2018-12-07 22:26:36 -07:00
Jens Axboe
344e9ffcbd block: add queue_is_mq() helper
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>
2018-11-16 08:34:06 -07:00
Christoph Hellwig
0d945c1f96 block: remove the queue_lock indirection
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>
2018-11-15 12:17:28 -07:00
Christoph Hellwig
7fb1763de6 blk-cgroup: move locking into blkg_destroy_all
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-15 12:13:28 -07:00
Christoph Hellwig
04be60b5e4 blk-cgroup: consolidate error handling in blkcg_init_queue
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>
2018-11-15 12:13:26 -07:00
Christoph Hellwig
b6676f653f block: remove a few unused exports
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-15 12:13:25 -07:00
Christoph Hellwig
8f4236d900 block: remove QUEUE_FLAG_BYPASS and ->bypass
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>
2018-11-15 12:13:15 -07:00
Jens Axboe
db6d995235 block: remove request_list code
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>
2018-11-07 13:42:33 -07:00
Jens Axboe
2cdf2caecd blk-cgroup: remove legacy queue bypassing
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>
2018-11-07 13:42:32 -07:00
Dennis Zhou
b5f2954d30 blkcg: revert blkcg cleanups series
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:
d459d853c2, b2c3fa5467, 101246ec02, b3b9f24f5f, e2b0989954,
f0fcb3ec89, c839e7a03f, bdc2491708, 74b7c02a9b, 5bf9a1f3b4,
a7b39b4e96, 07b05bcc32, 49f4c2dc2b, 27e6fa996c

Signed-off-by: Dennis Zhou <dennis@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-01 19:59:53 -06:00
Jens Axboe
c0aac682fa This is the 4.19-rc6 release
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Merge tag 'v4.19-rc6' into for-4.20/block

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>
2018-10-01 08:58:57 -06:00
Dennis Zhou (Facebook)
101246ec02 blkcg: rename blkg_try_get to blkg_tryget
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>
2018-09-21 20:29:19 -06:00
Dennis Zhou (Facebook)
b3b9f24f5f blkcg: change blkg reference counting to use percpu_ref
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>
2018-09-21 20:29:18 -06:00
Dennis Zhou (Facebook)
07b05bcc32 blkcg: convert blkg_lookup_create to find closest blkg
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>
2018-09-21 20:29:05 -06:00
Dennis Zhou (Facebook)
49f4c2dc2b blkcg: update blkg_lookup_create to do locking
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>
2018-09-21 20:29:03 -06:00
Jens Axboe
01c5f85aeb blk-cgroup: increase number of supported policies
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>
2018-09-11 10:59:53 -06:00