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* blkcg: remove blkcg->idTejun Heo2014-09-081-3/+0
| | | | | | | | | | | | | blkcg->id is a unique id given to each blkcg; however, the cgroup_subsys_state which each blkcg embeds already has ->serial_nr which can be used for the same purpose. Drop blkcg->id and replace its uses with blkcg->css.serial_nr. Rename cfq_cgroup->blkcg_id to ->blkcg_serial_nr and @id in check_blkcg_changed() to @serial_nr for consistency. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* Revert "block: add __init to blkcg_policy_register"Jens Axboe2014-06-231-2/+2
| | | | | | | This reverts commit a2d445d440003f2d70ee4cd4970ea82ace616fee. The original commit is buggy, we do use the registration functions at runtime for modular builds.
* blkcg: fix use-after-free in __blkg_release_rcu() by making blkcg_gq refcnt ↵Tejun Heo2014-06-231-10/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | an atomic_t Hello, So, this patch should do. Joe, Vivek, can one of you guys please verify that the oops goes away with this patch? Jens, the original thread can be read at http://thread.gmane.org/gmane.linux.kernel/1720729 The fix converts blkg->refcnt from int to atomic_t. It does some overhead but it should be minute compared to everything else which is going on and the involved cacheline bouncing, so I think it's highly unlikely to cause any noticeable difference. Also, the refcnt in question should be converted to a perpcu_ref for blk-mq anyway, so the atomic_t is likely to go away pretty soon anyway. Thanks. ------- 8< ------- __blkg_release_rcu() may be invoked after the associated request_queue is released with a RCU grace period inbetween. As such, the function and callbacks invoked from it must not dereference the associated request_queue. This is clearly indicated in the comment above the function. Unfortunately, while trying to fix a different issue, 2a4fd070ee85 ("blkcg: move bulk of blkcg_gq release operations to the RCU callback") ignored this and added [un]locking of @blkg->q->queue_lock to __blkg_release_rcu(). This of course can cause oops as the request_queue may be long gone by the time this code gets executed. general protection fault: 0000 [#1] SMP CPU: 21 PID: 30 Comm: rcuos/21 Not tainted 3.15.0 #1 Hardware name: Stratus ftServer 6400/G7LAZ, BIOS BIOS Version 6.3:57 12/25/2013 task: ffff880854021de0 ti: ffff88085403c000 task.ti: ffff88085403c000 RIP: 0010:[<ffffffff8162e9e5>] [<ffffffff8162e9e5>] _raw_spin_lock_irq+0x15/0x60 RSP: 0018:ffff88085403fdf0 EFLAGS: 00010086 RAX: 0000000000020000 RBX: 0000000000000010 RCX: 0000000000000000 RDX: 000060ef80008248 RSI: 0000000000000286 RDI: 6b6b6b6b6b6b6b6b RBP: ffff88085403fdf0 R08: 0000000000000286 R09: 0000000000009f39 R10: 0000000000020001 R11: 0000000000020001 R12: ffff88103c17a130 R13: ffff88103c17a080 R14: 0000000000000000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88107fca0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000006e5ab8 CR3: 000000000193d000 CR4: 00000000000407e0 Stack: ffff88085403fe18 ffffffff812cbfc2 ffff88103c17a130 0000000000000000 ffff88103c17a130 ffff88085403fec0 ffffffff810d1d28 ffff880854021de0 ffff880854021de0 ffff88107fcaec58 ffff88085403fe80 ffff88107fcaec30 Call Trace: [<ffffffff812cbfc2>] __blkg_release_rcu+0x72/0x150 [<ffffffff810d1d28>] rcu_nocb_kthread+0x1e8/0x300 [<ffffffff81091d81>] kthread+0xe1/0x100 [<ffffffff8163813c>] ret_from_fork+0x7c/0xb0 Code: ff 47 04 48 8b 7d 08 be 00 02 00 00 e8 55 48 a4 ff 5d c3 0f 1f 00 66 66 66 66 90 55 48 89 e5 +fa 66 66 90 66 66 90 b8 00 00 02 00 <f0> 0f c1 07 89 c2 c1 ea 10 66 39 c2 75 02 5d c3 83 e2 fe 0f +b7 RIP [<ffffffff8162e9e5>] _raw_spin_lock_irq+0x15/0x60 RSP <ffff88085403fdf0> The request_queue locking was added because blkcg_gq->refcnt is an int protected with the queue lock and __blkg_release_rcu() needs to put the parent. Let's fix it by making blkcg_gq->refcnt an atomic_t and dropping queue locking in the function. Given the general heavy weight of the current request_queue and blkcg operations, this is unlikely to cause any noticeable overhead. Moreover, blkcg_gq->refcnt is likely to be converted to percpu_ref in the near future, so whatever (most likely negligible) overhead it may add is temporary. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Joe Lawrence <joe.lawrence@stratus.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Link: http://lkml.kernel.org/g/alpine.DEB.2.02.1406081816540.17948@jlaw-desktop.mno.stratus.com Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe <axboe@fb.com>
* Merge branch 'for-linus' of git://git.kernel.dk/linux-blockLinus Torvalds2014-06-111-2/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull block layer fixes from Jens Axboe: "Final small batch of fixes to be included before -rc1. Some general cleanups in here as well, but some of the blk-mq fixes we need for the NVMe conversion and/or scsi-mq. The pull request contains: - Support for not merging across a specified "chunk size", if set by the driver. Some NVMe devices perform poorly for IO that crosses such a chunk, so we need to support it generically as part of request merging avoid having to do complicated split logic. From me. - Bump max tag depth to 10Ki tags. Some scsi devices have a huge shared tag space. Before we failed with EINVAL if a too large tag depth was specified, now we truncate it and pass back the actual value. From me. - Various blk-mq rq init fixes from me and others. - A fix for enter on a dying queue for blk-mq from Keith. This is needed to prevent oopsing on hot device removal. - Fixup for blk-mq timer addition from Ming Lei. - Small round of performance fixes for mtip32xx from Sam Bradshaw. - Minor stack leak fix from Rickard Strandqvist. - Two __init annotations from Fabian Frederick" * 'for-linus' of git://git.kernel.dk/linux-block: block: add __init to blkcg_policy_register block: add __init to elv_register block: ensure that bio_add_page() always accepts a page for an empty bio blk-mq: add timer in blk_mq_start_request blk-mq: always initialize request->start_time block: blk-exec.c: Cleaning up local variable address returnd mtip32xx: minor performance enhancements blk-mq: ->timeout should be cleared in blk_mq_rq_ctx_init() blk-mq: don't allow queue entering for a dying queue blk-mq: bump max tag depth to 10K tags block: add blk_rq_set_block_pc() block: add notion of a chunk size for request merging
| * block: add __init to blkcg_policy_registerFabian Frederick2014-06-101-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | blkcg_policy_register is only called by __init functions: __init cfq_init __init throtl_init Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Fabian Frederick <fabf@skynet.be> Signed-off-by: Jens Axboe <axboe@fb.com>
* | cgroup: remove css_parent()Tejun Heo2014-05-161-1/+1
|/ | | | | | | | | | | | | | | | | | | | | | | cgroup in general is moving towards using cgroup_subsys_state as the fundamental structural component and css_parent() was introduced to convert from using cgroup->parent to css->parent. It was quite some time ago and we're moving forward with making css more prominent. This patch drops the trivial wrapper css_parent() and let the users dereference css->parent. While at it, explicitly mark fields of css which are public and immutable. v2: New usage from device_cgroup.c converted. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: "David S. Miller" <davem@davemloft.net> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Johannes Weiner <hannes@cmpxchg.org>
* Merge branch 'for-3.15' of ↵Linus Torvalds2014-04-031-5/+9
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup updates from Tejun Heo: "A lot updates for cgroup: - The biggest one is cgroup's conversion to kernfs. cgroup took after the long abandoned vfs-entangled sysfs implementation and made it even more convoluted over time. cgroup's internal objects were fused with vfs objects which also brought in vfs locking and object lifetime rules. Naturally, there are places where vfs rules don't fit and nasty hacks, such as credential switching or lock dance interleaving inode mutex and cgroup_mutex with object serial number comparison thrown in to decide whether the operation is actually necessary, needed to be employed. After conversion to kernfs, internal object lifetime and locking rules are mostly isolated from vfs interactions allowing shedding of several nasty hacks and overall simplification. This will also allow implmentation of operations which may affect multiple cgroups which weren't possible before as it would have required nesting i_mutexes. - Various simplifications including dropping of module support, easier cgroup name/path handling, simplified cgroup file type handling and task_cg_lists optimization. - Prepatory changes for the planned unified hierarchy, which is still a patchset away from being actually operational. The dummy hierarchy is updated to serve as the default unified hierarchy. Controllers which aren't claimed by other hierarchies are associated with it, which BTW was what the dummy hierarchy was for anyway. - Various fixes from Li and others. This pull request includes some patches to add missing slab.h to various subsystems. This was triggered xattr.h include removal from cgroup.h. cgroup.h indirectly got included a lot of files which brought in xattr.h which brought in slab.h. There are several merge commits - one to pull in kernfs updates necessary for converting cgroup (already in upstream through driver-core), others for interfering changes in the fixes branch" * 'for-3.15' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (74 commits) cgroup: remove useless argument from cgroup_exit() cgroup: fix spurious lockdep warning in cgroup_exit() cgroup: Use RCU_INIT_POINTER(x, NULL) in cgroup.c cgroup: break kernfs active_ref protection in cgroup directory operations cgroup: fix cgroup_taskset walking order cgroup: implement CFTYPE_ONLY_ON_DFL cgroup: make cgrp_dfl_root mountable cgroup: drop const from @buffer of cftype->write_string() cgroup: rename cgroup_dummy_root and related names cgroup: move ->subsys_mask from cgroupfs_root to cgroup cgroup: treat cgroup_dummy_root as an equivalent hierarchy during rebinding cgroup: remove NULL checks from [pr_cont_]cgroup_{name|path}() cgroup: use cgroup_setup_root() to initialize cgroup_dummy_root cgroup: reorganize cgroup bootstrapping cgroup: relocate setting of CGRP_DEAD cpuset: use rcu_read_lock() to protect task_cs() cgroup_freezer: document freezer_fork() subtleties cgroup: update cgroup_transfer_tasks() to either succeed or fail cgroup: drop task_lock() protection around task->cgroups cgroup: update how a newly forked task gets associated with css_set ...
| * cgroup: remove cgroup->nameTejun Heo2014-02-121-4/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | cgroup->name handling became quite complicated over time involving dedicated struct cgroup_name for RCU protection. Now that cgroup is on kernfs, we can drop all of it and simply use kernfs_name/path() and friends. Replace cgroup->name and all related code with kernfs name/path constructs. * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top of kernfs counterparts, which involves semantic changes. pr_cont_cgroup_name() and pr_cont_cgroup_path() added. * cgroup->name handling dropped from cgroup_rename(). * All users of cgroup_name/path() updated to the new semantics. Users which were formatting the string just to printk them are converted to use pr_cont_cgroup_name/path() instead, which simplifies things quite a bit. As cgroup_name() no longer requires RCU read lock around it, RCU lockings which were protecting only cgroup_name() are removed. v2: Comment above oom_info_lock updated as suggested by Michal. v3: dummy_top doesn't have a kn associated and pr_cont_cgroup_name/path() ended up calling the matching kernfs functions with NULL kn leading to oops. Test for NULL kn and print "/" if so. This issue was reported by Fengguang Wu. v4: Rebased on top of 0ab02ca8f887 ("cgroup: protect modifications to cgroup_idr with cgroup_mutex"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Fengguang Wu <fengguang.wu@intel.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
| * cgroup: clean up cgroup_subsys names and initializationTejun Heo2014-02-081-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | cgroup_subsys is a bit messier than it needs to be. * The name of a subsys can be different from its internal identifier defined in cgroup_subsys.h. Most subsystems use the matching name but three - cpu, memory and perf_event - use different ones. * cgroup_subsys_id enums are postfixed with _subsys_id and each cgroup_subsys is postfixed with _subsys. cgroup.h is widely included throughout various subsystems, it doesn't and shouldn't have claim on such generic names which don't have any qualifier indicating that they belong to cgroup. * cgroup_subsys->subsys_id should always equal the matching cgroup_subsys_id enum; however, we require each controller to initialize it and then BUG if they don't match, which is a bit silly. This patch cleans up cgroup_subsys names and initialization by doing the followings. * cgroup_subsys_id enums are now postfixed with _cgrp_id, and each cgroup_subsys with _cgrp_subsys. * With the above, renaming subsys identifiers to match the userland visible names doesn't cause any naming conflicts. All non-matching identifiers are renamed to match the official names. cpu_cgroup -> cpu mem_cgroup -> memory perf -> perf_event * controllers no longer need to initialize ->subsys_id and ->name. They're generated in cgroup core and set automatically during boot. * Redundant cgroup_subsys declarations removed. * While updating BUG_ON()s in cgroup_init_early(), convert them to WARN()s. BUGging that early during boot is stupid - the kernel can't print anything, even through serial console and the trap handler doesn't even link stack frame properly for back-tracing. This patch doesn't introduce any behavior changes. v2: Rebased on top of fe1217c4f3f7 ("net: net_cls: move cgroupfs classid handling into core"). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Horman <nhorman@tuxdriver.com> Acked-by: "David S. Miller" <davem@davemloft.net> Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Ingo Molnar <mingo@redhat.com> Acked-by: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Serge E. Hallyn <serue@us.ibm.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Thomas Graf <tgraf@suug.ch>
* | net: Replace u64_stats_fetch_begin_bh to u64_stats_fetch_begin_irqEric W. Biederman2014-03-151-4/+4
|/ | | | | | | | | | | | | | | Replace the bh safe variant with the hard irq safe variant. We need a hard irq safe variant to deal with netpoll transmitting packets from hard irq context, and we need it in most if not all of the places using the bh safe variant. Except on 32bit uni-processor the code is exactly the same so don't bother with a bh variant, just have a hard irq safe variant that everyone can use. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* Update of blkg_stat and blkg_rwstat may happen in bh context.Hong Zhiguo2013-11-201-4/+4
| | | | | | | | | | | While u64_stats_fetch_retry is only preempt_disable on 32bit UP system. This is not enough to avoid preemption by bh and may read strange 64 bit value. Signed-off-by: Hong Zhiguo <zhiguohong@tencent.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: stable@kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: Use u64_stats_init() to initialize seqcountsPeter Zijlstra2013-11-131-0/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Now that seqcounts are lockdep enabled objects, we need to explicitly initialize runtime allocated seqcounts so that lockdep can track them. Without this patch, Fengguang was seeing: [ 4.127282] INFO: trying to register non-static key. [ 4.128027] the code is fine but needs lockdep annotation. [ 4.128027] turning off the locking correctness validator. [ 4.128027] CPU: 0 PID: 96 Comm: kworker/u4:1 Not tainted 3.12.0-next-20131108-10601-gbad570d #2 [ 4.128027] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ ... ] [ 4.128027] Call Trace: [ 4.128027] [<7908e744>] ? console_unlock+0x353/0x380 [ 4.128027] [<79dc7cf2>] dump_stack+0x48/0x60 [ 4.128027] [<7908953e>] __lock_acquire.isra.26+0x7e3/0xceb [ 4.128027] [<7908a1c5>] lock_acquire+0x71/0x9a [ 4.128027] [<794079aa>] ? blk_throtl_bio+0x1c3/0x485 [ 4.128027] [<7940658b>] throtl_update_dispatch_stats+0x7c/0x153 [ 4.128027] [<794079aa>] ? blk_throtl_bio+0x1c3/0x485 [ 4.128027] [<794079aa>] blk_throtl_bio+0x1c3/0x485 ... Use u64_stats_init() for all affected data structures, which initializes the seqcount. Reported-and-Tested-by: Fengguang Wu <fengguang.wu@intel.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Peter Zijlstra <peterz@infradead.org> [ Folded in another fix from the mailing list as well as a fix to that fix. Tweaked commit message. ] Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1384314134-6895-1-git-send-email-john.stultz@linaro.org [ So I actually think that the two SOBs from PeterZ are the right depiction of the patch route. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
* cgroup: make css_for_each_descendant() and friends include the origin css in ↵Tejun Heo2013-08-091-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | the iteration Previously, all css descendant iterators didn't include the origin (root of subtree) css in the iteration. The reasons were maintaining consistency with css_for_each_child() and that at the time of introduction more use cases needed skipping the origin anyway; however, given that css_is_descendant() considers self to be a descendant, omitting the origin css has become more confusing and looking at the accumulated use cases rather clearly indicates that including origin would result in simpler code overall. While this is a change which can easily lead to subtle bugs, cgroup API including the iterators has recently gone through major restructuring and no out-of-tree changes will be applicable without adjustments making this a relatively acceptable opportunity for this type of change. The conversions are mostly straight-forward. If the iteration block had explicit origin handling before or after, it's moved inside the iteration. If not, if (pos == origin) continue; is added. Some conversions add extra reference get/put around origin handling by consolidating origin handling and the rest. While the extra ref operations aren't strictly necessary, this shouldn't cause any noticeable difference. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Acked-by: Michal Hocko <mhocko@suse.cz> Cc: Jens Axboe <axboe@kernel.dk> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com>
* cgroup: make hierarchy iterators deal with cgroup_subsys_state instead of cgroupTejun Heo2013-08-091-16/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | cgroup is currently in the process of transitioning to using css (cgroup_subsys_state) as the primary handle instead of cgroup in subsystem API. For hierarchy iterators, this is beneficial because * In most cases, css is the only thing subsystems care about anyway. * On the planned unified hierarchy, iterations for different subsystems will need to skip over different subtrees of the hierarchy depending on which subsystems are enabled on each cgroup. Passing around css makes it unnecessary to explicitly specify the subsystem in question as css is intersection between cgroup and subsystem * For the planned unified hierarchy, css's would need to be created and destroyed dynamically independent from cgroup hierarchy. Having cgroup core manage css iteration makes enforcing deref rules a lot easier. Most subsystem conversions are straight-forward. Noteworthy changes are * blkio: cgroup_to_blkcg() is no longer used. Removed. * freezer: cgroup_freezer() is no longer used. Removed. * devices: cgroup_to_devcgroup() is no longer used. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com> Acked-by: Michal Hocko <mhocko@suse.cz> Acked-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Aristeu Rozanski <aris@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Jens Axboe <axboe@kernel.dk>
* cgroup: add css_parent()Tejun Heo2013-08-091-3/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | Currently, controllers have to explicitly follow the cgroup hierarchy to find the parent of a given css. cgroup is moving towards using cgroup_subsys_state as the main controller interface construct, so let's provide a way to climb the hierarchy using just csses. This patch implements css_parent() which, given a css, returns its parent. The function is guarnateed to valid non-NULL parent css as long as the target css is not at the top of the hierarchy. freezer, cpuset, cpu, cpuacct, hugetlb, memory, net_cls and devices are converted to use css_parent() instead of accessing cgroup->parent directly. * __parent_ca() is dropped from cpuacct and its usage is replaced with parent_ca(). The only difference between the two was NULL test on cgroup->parent which is now embedded in css_parent() making the distinction moot. Note that eventually a css->parent field will be added to css and the NULL check in css_parent() will go away. This patch shouldn't cause any behavior differences. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
* cgroup: add/update accessors which obtain subsys specific data from cssTejun Heo2013-08-091-4/+8
| | | | | | | | | | | | | | | | | | | | | | | | css (cgroup_subsys_state) is usually embedded in a subsys specific data structure. Subsystems either use container_of() directly to cast from css to such data structure or has an accessor function wrapping such cast. As cgroup as whole is moving towards using css as the main interface handle, add and update such accessors to ease dealing with css's. All accessors explicitly handle NULL input and return NULL in those cases. While this looks like an extra branch in the code, as all controllers specific data structures have css as the first field, the casting doesn't involve any offsetting and the compiler can trivially optimize out the branch. * blkio, freezer, cpuset, cpu, cpuacct and net_cls didn't have such accessor. Added. * memory, hugetlb and devices already had one but didn't explicitly handle NULL input. Updated. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
* cgroup: s/cgroup_subsys_state/cgroup_css/ s/task_subsys_state/task_css/Tejun Heo2013-08-091-3/+2
| | | | | | | | | | | | | | | | | | The names of the two struct cgroup_subsys_state accessors - cgroup_subsys_state() and task_subsys_state() - are somewhat awkward. The former clashes with the type name and the latter doesn't even indicate it's somehow related to cgroup. We're about to revamp large portion of cgroup API, so, let's rename them so that they're less awkward. Most per-controller usages of the accessors are localized in accessor wrappers and given the amount of scheduled changes, this isn't gonna add any noticeable headache. Rename cgroup_subsys_state() to cgroup_css() and task_subsys_state() to task_css(). This patch is pure rename. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Li Zefan <lizefan@huawei.com>
* blkcg: move bulk of blkcg_gq release operations to the RCU callbackTejun Heo2013-05-141-2/+2
| | | | | | | | | | | | | | | | | | | | | | Currently, when the last reference of a blkcg_gq is put, all then release operations sans the actual freeing happen directly in blkg_put(). As blkg_put() may be called under queue_lock, all pd_exit_fn()s may be too. This makes it impossible for pd_exit_fn()s to use del_timer_sync() on timers which grab the queue_lock which is an irq-safe lock due to the deadlock possibility described in the comment on top of del_timer_sync(). This can be easily avoided by perfoming the release operations in the RCU callback instead of directly from blkg_put(). This patch moves the blkcg_gq release operations to the RCU callback. As this leaves __blkg_release() with only call_rcu() invocation, blkg_rcu_free() is renamed to __blkg_release_rcu(), exported and call_rcu() invocation is now done directly from blkg_put() instead of going through __blkg_release() which is removed. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Vivek Goyal <vgoyal@redhat.com>
* blkcg: implement blkg_for_each_descendant_post()Tejun Heo2013-05-141-0/+14
| | | | | | | This will be used by blk-throttle hierarchy support. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Vivek Goyal <vgoyal@redhat.com>
* blkcg: move blkg_for_each_descendant_pre() to block/blk-cgroup.hTejun Heo2013-05-141-0/+20
| | | | | | | | | blk-throttle hierarchy support will make use of it. Move blkg_for_each_descendant_pre() from block/blk-cgroup.c to block/blk-cgroup.h. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Vivek Goyal <vgoyal@redhat.com>
* cgroup: fix cgroup_path() vs rename() raceLi Zefan2013-03-041-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | rename() will change dentry->d_name. The result of this race can be worse than seeing partially rewritten name, but we might access a stale pointer because rename() will re-allocate memory to hold a longer name. As accessing dentry->name must be protected by dentry->d_lock or parent inode's i_mutex, while on the other hand cgroup-path() can be called with some irq-safe spinlocks held, we can't generate cgroup path using dentry->d_name. Alternatively we make a copy of dentry->d_name and save it in cgrp->name when a cgroup is created, and update cgrp->name at rename(). v5: use flexible array instead of zero-size array. v4: - allocate root_cgroup_name and all root_cgroup->name points to it. - add cgroup_name() wrapper. v3: use kfree_rcu() instead of synchronize_rcu() in user-visible path. v2: make cgrp->name RCU safe. Signed-off-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* blkcg: implement blkg_[rw]stat_recursive_sum() and blkg_[rw]stat_merge()Tejun Heo2013-01-091-0/+35
| | | | | | | | | | | | | | | | Implement blkg_[rw]stat_recursive_sum() and blkg_[rw]stat_merge(). The former two collect the [rw]stats designated by the target policy data and offset from the pd's subtree. The latter two add one [rw]stat to another. Note that the recursive sum functions require the queue lock to be held on entry to make blkg online test reliable. This is necessary to properly handle stats of a dying blkg. These will be used to implement hierarchical stats. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Vivek Goyal <vgoyal@redhat.com>
* blkcg: s/blkg_rwstat_sum()/blkg_rwstat_total()/Tejun Heo2013-01-091-2/+2
| | | | | | | | Rename blkg_rwstat_sum() to blkg_rwstat_total(). sum will be used for summing up stats from multiple blkgs. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Vivek Goyal <vgoyal@redhat.com>
* blkcg: implement blkcg_policy->on/offline_pd_fn() and blkcg_gq->onlineTejun Heo2013-01-091-0/+7
| | | | | | | | | | | | | | | Add two blkcg_policy methods, ->online_pd_fn() and ->offline_pd_fn(), which are invoked as the policy_data gets activated and deactivated while holding both blkcg and q locks. Also, add blkcg_gq->online bool, which is set and cleared as the blkcg_gq gets activated and deactivated. This flag also is toggled while holding both blkcg and q locks. These will be used to implement hierarchical stats. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Vivek Goyal <vgoyal@redhat.com>
* blkcg: add blkg_policy_data->plidTejun Heo2013-01-091-1/+2
| | | | | | | | Add pd->plid so that the policy a pd belongs to can be identified easily. This will be used to implement hierarchical blkg_[rw]stats. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Vivek Goyal <vgoyal@redhat.com>
* cfq-iosched: add leaf_weightTejun Heo2013-01-091-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | cfq blkcg is about to grow proper hierarchy handling, where a child blkg's weight would nest inside the parent's. This makes tasks in a blkg to compete against both tasks in the sibling blkgs and the tasks of child blkgs. We're gonna use the existing weight as the group weight which decides the blkg's weight against its siblings. This patch introduces a new weight - leaf_weight - which decides the weight of a blkg against the child blkgs. It's named leaf_weight because another way to look at it is that each internal blkg nodes have a hidden child leaf node which contains all its tasks and leaf_weight is the weight of the leaf node and handled the same as the weight of the child blkgs. This patch only adds leaf_weight fields and exposes it to userland. The new weight isn't actually used anywhere yet. Note that cfq-iosched currently offcially supports only single level hierarchy and root blkgs compete with the first level blkgs - ie. root weight is basically being used as leaf_weight. For root blkgs, the two weights are kept in sync for backward compatibility. v2: cfqd->root_group->leaf_weight initialization was missing from cfq_init_queue() causing divide by zero when !CONFIG_CFQ_GROUP_SCHED. Fix it. Reported by Fengguang. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Fengguang Wu <fengguang.wu@intel.com>
* blkcg: make blkcg_gq's hierarchicalTejun Heo2013-01-091-0/+18
| | | | | | | | | | | | | | | | | | | | Currently a child blkg (blkcg_gq) can be created even if its parent doesn't exist. ie. Given a blkg, it's not guaranteed that its ancestors will exist. This makes it difficult to implement proper hierarchy support for blkcg policies. Always create blkgs recursively and make a child blkg hold a reference to its parent. blkg->parent is added so that finding the parent is easy. blkcg_parent() is also added in the process. This change can be visible to userland. e.g. while issuing IO in a nested cgroup didn't affect the ancestors at all, now it will initialize all ancestor blkgs and zero stats for the request_queue will always appear on them. While this is userland visible, this shouldn't cause any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Vivek Goyal <vgoyal@redhat.com>
* blkcg: implement per-blkg request allocationTejun Heo2012-06-271-0/+102
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, request_queue has one request_list to allocate requests from regardless of blkcg of the IO being issued. When the unified request pool is used up, cfq proportional IO limits become meaningless - whoever grabs the next request being freed wins the race regardless of the configured weights. This can be easily demonstrated by creating a blkio cgroup w/ very low weight, put a program which can issue a lot of random direct IOs there and running a sequential IO from a different cgroup. As soon as the request pool is used up, the sequential IO bandwidth crashes. This patch implements per-blkg request_list. Each blkg has its own request_list and any IO allocates its request from the matching blkg making blkcgs completely isolated in terms of request allocation. * Root blkcg uses the request_list embedded in each request_queue, which was renamed to @q->root_rl from @q->rq. While making blkcg rl handling a bit harier, this enables avoiding most overhead for root blkcg. * Queue fullness is properly per request_list but bdi isn't blkcg aware yet, so congestion state currently just follows the root blkcg. As writeback isn't aware of blkcg yet, this works okay for async congestion but readahead may get the wrong signals. It's better than blkcg completely collapsing with shared request_list but needs to be improved with future changes. * After this change, each block cgroup gets a full request pool making resource consumption of each cgroup higher. This makes allowing non-root users to create cgroups less desirable; however, note that allowing non-root users to directly manage cgroups is already severely broken regardless of this patch - each block cgroup consumes kernel memory and skews IO weight (IO weights are not hierarchical). v2: queue-sysfs.txt updated and patch description udpated as suggested by Vivek. v3: blk_get_rl() wasn't checking error return from blkg_lookup_create() and may cause oops on lookup failure. Fix it by falling back to root_rl on blkg lookup failures. This problem was spotted by Rakesh Iyer <rni@google.com>. v4: Updated to accomodate 458f27a982 "block: Avoid missed wakeup in request waitqueue". blk_drain_queue() now wakes up waiters on all blkg->rl on the target queue. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Vivek Goyal <vgoyal@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blkcg: inline bio_blkcg() and friendsTejun Heo2012-06-251-4/+22
| | | | | | | | | | | | Make bio_blkcg() and friends inline. They all are very simple and used only in few places. This patch is to prepare for further updates to request allocation path. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blkcg: use radix tree to index blkgs from blkcgTejun Heo2012-04-201-0/+6
| | | | | | | | | | | | | | | | | | | | blkg lookup is currently performed by traversing linked list anchored at blkcg->blkg_list. This is very unscalable and with blk-throttle enabled and enough request queues on the system, this can get very ugly quickly (blk-throttle performs look up on every bio submission). This patch makes blkcg use radix tree to index blkgs combined with simple last-looked-up hint. This is mostly identical to how icqs are indexed from ioc. Note that because __blkg_lookup() may be invoked without holding queue lock, hint is only updated from __blkg_lookup_create(). Due to cfq's cfqq caching, this makes hint updates overly lazy. This will be improved with scheduled blkcg aware request allocation. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blkcg: collapse blkcg_policy_ops into blkcg_policyTejun Heo2012-04-201-7/+5
| | | | | | | | | | | There's no reason to keep blkcg_policy_ops separate. Collapse it into blkcg_policy. This patch doesn't introduce any functional change. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blkcg: embed struct blkg_policy_data in policy specific dataTejun Heo2012-04-201-26/+34
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently blkg_policy_data carries policy specific data as char flex array instead of being embedded in policy specific data. This was forced by oddities around blkg allocation which are all gone now. This patch makes blkg_policy_data embedded in policy specific data - throtl_grp and cfq_group so that it's more conventional and consistent with how io_cq is handled. * blkcg_policy->pdata_size is renamed to ->pd_size. * Functions which used to take void *pdata now takes struct blkg_policy_data *pd. * blkg_to_pdata/pdata_to_blkg() updated to blkg_to_pd/pd_to_blkg(). * Dummy struct blkg_policy_data definition added. Dummy pdata_to_blkg() definition was unused and inconsistent with the non-dummy version - correct dummy pd_to_blkg() added. * throtl and cfq updated accordingly. * As dummy blkg_to_pd/pd_to_blkg() are provided, blkg_to_cfqg/cfqg_to_blkg() don't need to be ifdef'd. Moved outside ifdef block. This patch doesn't introduce any functional change. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blkcg: mass rename of blkcg APITejun Heo2012-04-201-55/+54
| | | | | | | | | | | | | | | | | | | | | | | | During the recent blkcg cleanup, most of blkcg API has changed to such extent that mass renaming wouldn't cause any noticeable pain. Take the chance and cleanup the naming. * Rename blkio_cgroup to blkcg. * Drop blkio / blkiocg prefixes and consistently use blkcg. * Rename blkio_group to blkcg_gq, which is consistent with io_cq but keep the blkg prefix / variable name. * Rename policy method type and field names to signify they're dealing with policy data. * Rename blkio_policy_type to blkcg_policy. This patch doesn't cause any functional change. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blkcg: style cleanups for blk-cgroup.hTejun Heo2012-04-201-56/+52
| | | | | | | | | | | | | | * Update indentation on struct field declarations. * Uniformly don't use "extern" on function declarations. * Merge the two #ifdef CONFIG_BLK_CGROUP blocks. All changes in this patch are cosmetic. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blkcg: remove blkio_group->path[]Tejun Heo2012-04-201-4/+17
| | | | | | | | | | blkio_group->path[] stores the path of the associated cgroup and is used only for debug messages. Just format the path from blkg->cgroup when printing debug messages. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blkcg: blkg_rwstat_read() was missing inlineTejun Heo2012-04-201-1/+1
| | | | | | | | | blkg_rwstat_read() in blk-cgroup.h was missing inline modifier causing compile warning depending on configuration. Add it. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blkcg: drop stuff unused after per-queue policy activation updateTejun Heo2012-04-201-5/+1
| | | | | | | | | | | | | | | | * All_q_list is unused. Drop all_q_{mutex|list}. * @for_root of blkg_lookup_create() is always %false when called from outside blk-cgroup.c proper. Factor out __blkg_lookup_create() so that it doesn't check whether @q is bypassing and use the underscored version for the @for_root callsite. * blkg_destroy_all() is used only from blkcg proper and @destroy_root is always %true. Make it static and drop @destroy_root. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blkcg: implement per-queue policy activationTejun Heo2012-04-201-4/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | All blkcg policies were assumed to be enabled on all request_queues. Due to various implementation obstacles, during the recent blkcg core updates, this was temporarily implemented as shooting down all !root blkgs on elevator switch and policy [de]registration combined with half-broken in-place root blkg updates. In addition to being buggy and racy, this meant losing all blkcg configurations across those events. Now that blkcg is cleaned up enough, this patch replaces the temporary implementation with proper per-queue policy activation. Each blkcg policy should call the new blkcg_[de]activate_policy() to enable and disable the policy on a specific queue. blkcg_activate_policy() allocates and installs policy data for the policy for all existing blkgs. blkcg_deactivate_policy() does the reverse. If a policy is not enabled for a given queue, blkg printing / config functions skip the respective blkg for the queue. blkcg_activate_policy() also takes care of root blkg creation, and cfq_init_queue() and blk_throtl_init() are updated accordingly. This replaces blkcg_bypass_{start|end}() and update_root_blkg_pd() unnecessary. Dropped. v2: cfq_init_queue() was returning uninitialized @ret on root_group alloc failure if !CONFIG_CFQ_GROUP_IOSCHED. Fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blkcg: make blkg_conf_prep() take @pol and return with queue lock heldTejun Heo2012-04-201-1/+2
| | | | | | | | | | | | | Add @pol to blkg_conf_prep() and let it return with queue lock held (to be released by blkg_conf_finish()). Note that @pol isn't used yet. This is to prepare for per-queue policy activation and doesn't cause any visible difference. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blkcg: remove static policy ID enumsTejun Heo2012-04-201-11/+4
| | | | | | | | | | | | | | Remove BLKIO_POLICY_* enums and let blkio_policy_register() allocate @pol->plid dynamically on registration. The maximum number of blkcg policies which can be registered at the same time is defined by BLKCG_MAX_POLS constant added to include/linux/blkdev.h. Note that blkio_policy_register() now may fail. Policy init functions updated accordingly and unnecessary ifdefs removed from cfq_init(). Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blkcg: use @pol instead of @plid in update_root_blkg_pd() and ↵Tejun Heo2012-04-201-3/+4
| | | | | | | | | | | | | | blkcg_print_blkgs() The two functions were taking "enum blkio_policy_id plid". Make them take "const struct blkio_policy_type *pol" instead. This is to prepare for per-queue policy activation and doesn't cause any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blkcg: kill blkio_list and replace blkio_list_lock with a mutexTejun Heo2012-04-201-1/+0
| | | | | | | | | | | | | | With blkio_policy[], blkio_list is redundant and hinders with per-queue policy activation. Remove it. Also, replace blkio_list_lock with a mutex blkcg_pol_mutex and let it protect the whole [un]registration. This is to prepare for per-queue policy activation and doesn't cause any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* cfq: fix build breakage & warningsTejun Heo2012-04-201-2/+2
| | | | | | | | | | | | | | * CFQ_WEIGHT_* defined inside CONFIG_BLK_CGROUP causes cfq-iosched.c compile failure when the config is disabled. Move it outside the ifdef block. * Dummy cfqg_stats_*() definitions were lacking inline modifiers causing unused functions warning if !CONFIG_CFQ_GROUP_IOSCHED. Add them. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blkcg: drop BLKCG_STAT_{PRIV|POL|OFF} macrosTejun Heo2012-04-011-9/+2
| | | | | | | | | | | | | | Now that all stat handling code lives in policy implementations, there's no need to encode policy ID in cft->private. * Export blkcg_prfill_[rw]stat() from blkcg, remove blkcg_print_[rw]stat(), and implement cfqg_print_[rw]stat() which use hard-code BLKIO_POLICY_PROP. * Use cft->private for offset of the target field directly and drop BLKCG_STAT_{PRIV|POL|OFF}(). Signed-off-by: Tejun Heo <tj@kernel.org>
* blkcg: pass around pd->pdata instead of pd itself in prfill functionsTejun Heo2012-04-011-3/+3
| | | | | | | | | Now that all conf and stat fields are moved into policy specific blkio_policy_data->pdata areas, there's no reason to use blkio_policy_data itself in prfill functions. Pass around @pd->pdata instead of @pd. Signed-off-by: Tejun Heo <tj@kernel.org>
* blkcg: move blkio_group_conf->iops and ->bps to blk-throttleTejun Heo2012-04-011-8/+0
| | | | | | | | | | blkio_cgroup_conf->iops and ->bps are owned by blk-throttle and has no reason to be defined in blkcg core. Drop them and let conf setting functions directly manipulate throtl_grp->bps[] and ->iops[]. This makes blkio_group_conf empty. Drop it. Signed-off-by: Tejun Heo <tj@kernel.org>
* blkcg: move blkio_group_conf->weight to cfqTejun Heo2012-04-011-6/+8
| | | | | | | | | | | | | | blkio_group_conf->weight is owned by cfq and has no reason to be defined in blkcg core. Replace it with cfq_group->dev_weight and let conf setting functions directly set it. If dev_weight is zero, the cfqg doesn't have device specific weight configured. Also, rename BLKIO_WEIGHT_* constants to CFQ_WEIGHT_* and rename blkio_cgroup->weight to blkio_cgroup->cfq_weight. We eventually want per-policy storage in blkio_cgroup but just mark the ownership of the field for now. Signed-off-by: Tejun Heo <tj@kernel.org>
* blkcg: move blkio_group_stats_cpu and friends to blk-throttle.cTejun Heo2012-04-011-13/+0
| | | | | | | | | | | | | | | | | | | | | | | | | blkio_group_stats_cpu is used only by blk-throtl and has no reason to be defined in blkcg core. * Move blkio_group_stats_cpu to blk-throttle.c and rename it to tg_stats_cpu. * blkg_policy_data->stats_cpu is replaced with throtl_grp->stats_cpu. prfill functions updated accordingly. * All related macros / functions are renamed so that they have tg_ prefix and the unnecessary @pol arguments are dropped. * Per-cpu stats allocation code is also moved from blk-cgroup.c to blk-throttle.c and gets simplified to only deal with BLKIO_POLICY_THROTL. percpu stat free is performed by the exit method throtl_exit_blkio_group(). * throtl_reset_group_stats() implemented for blkio_reset_group_stats_fn method so that tg->stats_cpu can be reset. Signed-off-by: Tejun Heo <tj@kernel.org>
* blkcg: move blkio_group_stats to cfq-iosched.cTejun Heo2012-04-011-41/+0
| | | | | | | | | | | | | | | | | | | | | | | | | blkio_group_stats contains only fields used by cfq and has no reason to be defined in blkcg core. * Move blkio_group_stats to cfq-iosched.c and rename it to cfqg_stats. * blkg_policy_data->stats is replaced with cfq_group->stats. blkg_prfill_[rw]stat() are updated to use offset against pd->pdata instead. * All related macros / functions are renamed so that they have cfqg_ prefix and the unnecessary @pol arguments are dropped. * All stat functions now take cfq_group * instead of blkio_group *. * lockdep assertion on queue lock dropped. Elevator runs under queue lock by default. There isn't much to be gained by adding lockdep assertions at stat function level. * cfqg_stats_reset() implemented for blkio_reset_group_stats_fn method so that cfqg->stats can be reset. Signed-off-by: Tejun Heo <tj@kernel.org>
* blkcg: add blkio_policy_ops operations for exit and stat resetTejun Heo2012-04-011-0/+4
| | | | | | | | Add blkio_policy_ops->blkio_exit_group_fn() and ->blkio_reset_group_stats_fn(). These will be used to further modularize blkcg policy implementation. Signed-off-by: Tejun Heo <tj@kernel.org>
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