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* blkcg: fix incorrect read/write sync/async stat accountingTejun Heo2015-10-271-2/+2
| | | | | | | | | | | | While unifying how blkcg stats are collected, 77ea733884eb ("blkcg: move io_service_bytes and io_serviced stats into blkcg_gq") incorrectly used bio->flags instead of bio->rw to tell the IO type. This made IOs to be accounted as the wrong type. Fix it. Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: 77ea733884eb ("blkcg: move io_service_bytes and io_serviced stats into blkcg_gq") Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: use CGROUP_WEIGHT_* scale for io.weight on the unified hierarchyTejun Heo2015-08-181-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | cgroup is trying to make interface consistent across different controllers. For weight based resource control, the knob should have the range [1, 10000] and default to 100. This patch updates cfq-iosched so that the weight range conforms. The internal calculations have enough range and the widening of the weight range shouldn't cause any problem. * blkcg_policy->cpd_bind_fn() is added. If present, this is invoked when blkcg is attached to a hierarchy. * cfq_cpd_init() is updated to use the new default value on the unified hierarchy. * cfq_cpd_bind() callback is implemented to clear per-blkg configs and apply the default config matching the hierarchy type. * cfqd->root_group->[leaf_]weight initialization in cfq_init_queue() is moved into !CONFIG_CFQ_GROUP_IOSCHED block. cfq_cpd_bind() is now responsible for initializing the initial weights when blkcg is enabled. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Arianna Avanzini <avanzini.arianna@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: implement interface for the unified hierarchyTejun Heo2015-08-181-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | blkcg interface grew to be the biggest of all controllers and unfortunately most inconsistent too. The interface files are inconsistent with a number of cloes duplicates. Some files have recursive variants while others don't. There's distinction between normal and leaf weights which isn't intuitive and there are a lot of stat knobs which don't make much sense outside of debugging and expose too much implementation details to userland. In the unified hierarchy, everything is always hierarchical and internal nodes can't have tasks rendering the two structural issues twisting the current interface. The interface has to be updated in a significant anyway and this is a good chance to revamp it as a whole. This patch implements blkcg interface for the unified hierarchy. * (from a previous patch) blkcg is identified by "io" instead of "blkio" on the unified hierarchy. Given that the whole interface is updated anyway, the rename shouldn't carry noticeable conversion overhead. * The original interface consisted of 27 files is replaced with the following three files. blkio.stat : per-blkcg stats blkio.weight : per-cgroup and per-cgroup-queue weight settings blkio.max : per-cgroup-queue bps and iops max limits Documentation/cgroups/unified-hierarchy.txt updated accordingly. v2: blkcg_policy->dfl_cftypes wasn't removed on blkcg_policy_unregister() corrupting the cftypes list. Fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: misc preparations for unified hierarchy interfaceTejun Heo2015-08-181-0/+1
| | | | | | | | | * Export blkg_dev_name() * Drop unnecessary @cft from __cfq_set_weight(). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: move body parsing from blkg_conf_prep() to its callersTejun Heo2015-08-181-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | Currently, blkg_conf_prep() expects input to be of the following form MAJ:MIN NUM and reads the NUM part into blkg_conf_ctx->v. This is quite restrictive and gets in the way in implementing blkcg interface for the unified hierarchy. This patch updates blkg_conf_prep() so that it expects MAJ:MIN BODY_STR where BODY_STR is an arbitrary string. blkg_conf_ctx->v is replaced with ->body which is a char pointer pointing to the start of BODY_STR. Parsing of the body is moved to blkg_conf_prep()'s callers. To allow using, for example, strsep() on blkg_conf_ctx->val, it is a non-const pointer and to accommodate that const is dropped from @input too. This doesn't cause any behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: mark existing cftypes as legacyTejun Heo2015-08-181-1/+1
| | | | | | | | | | | | | | | blkcg is about to grow interface for the unified hierarchy. Add legacy to existing cftypes. * blkcg_policy->cftypes -> blkcg_policy->legacy_cftypes * blk-cgroup.c:blkcg_files -> blkcg_legacy_files * cfq-iosched.c:cfq_blkcg_files -> cfq_blkcg_legacy_files * blk-throttle.c:throtl_files -> throtl_legacy_files Pure renames. No functional change. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: rename subsystem name from blkio to ioTejun Heo2015-08-181-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | blkio interface has become messy over time and is currently the largest. In addition to the inconsistent naming scheme, it has multiple stat files which report more or less the same thing, a number of debug stat files which expose internal details which shouldn't have been part of the public interface in the first place, recursive and non-recursive stats and leaf and non-leaf knobs. Both recursive vs. non-recursive and leaf vs. non-leaf distinctions don't make any sense on the unified hierarchy as only leaf cgroups can contain processes. cgroups is going through a major interface revision with the unified hierarchy involving significant fundamental usage changes and given that a significant portion of the interface doesn't make sense anymore, it's a good time to reorganize the interface. As the first step, this patch renames the external visible subsystem name from "blkio" to "io". This is more concise, matches the other two major subsystem names, "cpu" and "memory", and better suited as blkcg will be involved in anything writeback related too whether an actual block device is involved or not. As the subsystem legacy_name is set to "blkio", the only userland visible change outside the unified hierarchy is that blkcg is reported as "io" instead of "blkio" in the subsystem initialized message during boot. On the unified hierarchy, blkcg now appears as "io". Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: cgroups@vger.kernel.org Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: move io_service_bytes and io_serviced stats into blkcg_gqTejun Heo2015-08-181-0/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, both cfq-iosched and blk-throttle keep track of io_service_bytes and io_serviced stats. While keeping track of them separately may be useful during development, it doesn't make much sense otherwise. Also, blk-throttle was counting bio's as IOs while cfq-iosched request's, which is more confusing than informative. This patch adds ->stat_bytes and ->stat_ios to blkg (blkcg_gq), removes the counterparts from cfq-iosched and blk-throttle and let them print from the common blkg counters. The common counters are incremented during bio issue in blkcg_bio_issue_check(). The outputs are still filtered by whether the policy has blkg_policy_data on a given blkg, so cfq's output won't show up if it has never been used for a given blkg. The only times when the outputs would differ significantly are when policies are attached on the fly or elevators are switched back and forth. Those are quite exceptional operations and I don't think they warrant keeping separate counters. v3: Update blkio-controller.txt accordingly. v2: Account IOs during bio issues instead of request completions so that bio-based drivers can be handled the same way. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: make blkg_[rw]stat_recursive_sum() to be able to index into blkcg_gqTejun Heo2015-08-181-3/+4
| | | | | | | | | | | | | | | | Currently, blkg_[rw]stat_recursive_sum() assume that the target counter is located in pd (blkg_policy_data); however, some counters are planned to be moved to blkg (blkcg_gq). This patch updates blkg_[rw]stat_recursive_sum() to take blkg and blkg_policy pointers instead of pd. If policy is NULL, it indexes into blkg. If non-NULL, into the blkg's pd of the policy. The existing usages are updated to maintain the current behaviors. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: make blkcg_[rw]stat per-cpuTejun Heo2015-08-181-53/+67
| | | | | | | | | | | | | | | | | | | | | | | | | | | | blkcg_[rw]stat are used as stat counters for blkcg policies. It isn't per-cpu by itself and blk-throttle makes it per-cpu by wrapping around it. This patch makes blkcg_[rw]stat per-cpu and drop the ad-hoc per-cpu wrapping in blk-throttle. * blkg_[rw]stat->cnt is replaced with cpu_cnt which is struct percpu_counter. This makes syncp unnecessary as remote accesses are handled by percpu_counter itself. * blkg_[rw]stat_init() can now fail due to percpu allocation failure and thus are updated to return int. * percpu_counters need explicit freeing. blkg_[rw]stat_exit() added. * As blkg_rwstat->cpu_cnt[] can't be read directly anymore, reading and summing results are stored in ->aux_cnt[] instead. * Custom per-cpu stat implementation in blk-throttle is removed. This makes all blkcg stat counters per-cpu without complicating policy implmentations. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: add blkg_[rw]stat->aux_cnt and replace cfq_group->dead_stats with itTejun Heo2015-08-181-13/+33
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | cgroup stats are local to each cgroup and doesn't propagate to ancestors by default. When recursive stats are necessary, the sum is calculated over all the descendants. This initially was for backward compatibility to support both group-local and recursive stats but this mode of operation makes general sense as stat update is much hotter thafn reporting those stats. This however ends up losing recursive stats when a child is removed. To work around this, cfq-iosched adds its stats to its parent cfq_group->dead_stats which is summed up together when calculating recursive stats. It's planned that the core stats will be moved to blkcg_gq, so we want to move the mechanism for keeping track of the stats of dead children from cfq to blkcg core. This patch adds blkg_[rw]stat->aux_cnt which are atomic64_t's keeping track of auxiliary counts which are excluded when reading local counts but included for recursive. blkg_[rw]stat_merge() which were used by cfq to implement dead_stats are replaced by blkg_[rw]stat_add_aux(), and cfq now forwards stats of a dead cgroup to the aux counts of parent->stats instead of separate ->dead_stats. This will also help making blkg_[rw]stats per-cpu. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: consolidate blkg creation in blkcg_bio_issue_check()Tejun Heo2015-08-181-2/+38
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | blkg (blkcg_gq) currently is created by blkcg policies invoking blkg_lookup_create() which ends up repeating about the same code in different policies. Theoretically, this can avoid the overhead of looking and/or creating blkg's if blkcg is enabled but no policy is in use; however, the cost of blkg lookup / creation is very low especially if only the root blkcg is in use which is highly likely if no blkcg policy is in active use - it boils down to a single very predictable conditional and surrounding RCU protection. This patch consolidates blkg creation to a new function blkcg_bio_issue_check() which is called during bio issue from generic_make_request_checks(). blkcg_bio_issue_check() is now the only function which tries to create missing blkg's. The subsequent policy and request_list operations just perform blkg_lookup() and if missing falls back to the root. * blk_get_rl() no longer tries to create blkg. It uses blkg_lookup() instead of blkg_lookup_create(). * blk_throtl_bio() is now called from blkcg_bio_issue_check() with rcu read locked and blkg already looked up. Both throtl_lookup_tg() and throtl_lookup_create_tg() are dropped. * cfq is similarly updated. cfq_lookup_create_cfqg() is replaced with cfq_lookup_cfqg()which uses blkg_lookup(). This consolidates blkg handling and avoids unnecessary blkg creation retries under memory pressure. In addition, this provides a common bio entry point into blkcg where things like common accounting can be performed. v2: Build fixes for !CONFIG_CFQ_GROUP_IOSCHED and !CONFIG_BLK_DEV_THROTTLING. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Arianna Avanzini <avanzini.arianna@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: move root blkg lookup optimization from throtl_lookup_tg() to ↵Tejun Heo2015-08-181-0/+3
| | | | | | | | | | | | | | | __blkg_lookup() Currently, both throttle and cfq policies implement their own root blkg (blkcg_gq) lookup fast path. This patch moves root blkg optimization from throtl_lookup_tg() to __blkg_lookup(). cfq-iosched currently doesn't use blkg_lookup() but will be converted and drop the optimization too. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Arianna Avanzini <avanzini.arianna@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: inline [__]blkg_lookup()Tejun Heo2015-08-181-4/+45
| | | | | | | | | | | | | | | | | blkg_lookup() checks whether the target queue is bypassing and, if not, calls __blkg_lookup() which first checks the lookup hint and then performs radix tree walk. The operations upto hint checking are trivial and there are many users of this function. This patch inlines blkg_lookup() and the fast path part of __blkg_lookup(). The radix tree lookup and hint update are now in blkg_lookup_slowpath(). This will help consolidating blkg handling by easing moving root blkcg short-circuit to inlined lookup fast path. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Arianna Avanzini <avanzini.arianna@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: replace blkcg_policy->cpd_size with ->cpd_alloc/free_fn() methodsTejun Heo2015-08-181-7/+10
| | | | | | | | | | | | | | | | | | | | | | | | Each active policy has a cpd (blkcg_policy_data) on each blkcg. The cpd's were allocated by blkcg core and each policy could request to allocate extra space at the end by setting blkcg_policy->cpd_size larger than the size of cpd. This is a bit unusual but blkg (blkcg_gq) policy data used to be handled this way too so it made sense to be consistent; however, blkg policy data switched to alloc/free callbacks. This patch makes similar changes to cpd handling. blkcg_policy->cpd_alloc/free_fn() are added to replace ->cpd_size. As cpd allocation is now done from policy side, it can simply allocate a larger area which embeds cpd at the beginning. As ->cpd_alloc_fn() may be able to perform all necessary initializations, this patch makes ->cpd_init_fn() optional. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Arianna Avanzini <avanzini.arianna@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: minor updates around blkcg_policy_dataTejun Heo2015-08-181-4/+10
| | | | | | | | | | | | | | | | | | | | * Rename blkcg->pd[] to blkcg->cpd[] so that cpd is consistently used for blkcg_policy_data. * Make blkcg_policy->cpd_init_fn() take blkcg_policy_data instead of blkcg. This makes it consistent with blkg_policy_data methods and to-be-added cpd alloc/free methods. * blkcg_policy_data->blkcg and cpd_to_blkcg() added so that cpd_init_fn() can determine the associated blkcg from blkcg_policy_data. v2: blkcg_policy_data->blkcg initializations were missing. Added. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Arianna Avanzini <avanzini.arianna@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: make blkcg_policy methods take a pointer to blkcg_policy_dataTejun Heo2015-08-181-4/+4
| | | | | | | | | | | | | | | | | The newly added ->pd_alloc_fn() and ->pd_free_fn() deal with pd (blkg_policy_data) while the older ones use blkg (blkcg_gq). As using blkg doesn't make sense for ->pd_alloc_fn() and after allocation pd can always be mapped to blkg and given that these are policy-specific methods, it makes sense to converge on pd. This patch makes all methods deal with pd instead of blkg. Most conversions are trivial. In blk-cgroup.c, a couple method invocation sites now test whether pd exists instead of policy state for consistency. This shouldn't cause any behavioral differences. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-throttle: clean up blkg_policy_data alloc/init/exit/free methodsTejun Heo2015-08-181-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | With the recent addition of alloc and free methods, things became messier. This patch reorganizes them according to the followings. * ->pd_alloc_fn() Responsible for allocation and static initializations - the ones which can be done independent of where the pd might be attached. * ->pd_init_fn() Initializations which require the knowledge of where the pd is attached. * ->pd_free_fn() The counter part of pd_alloc_fn(). Static de-init and freeing. This leaves ->pd_exit_fn() without any users. Removed. While at it, collapse an one liner function throtl_pd_exit(), which has only one user, into its user. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: replace blkcg_policy->pd_size with ->pd_alloc/free_fn() methodsTejun Heo2015-08-181-9/+9
| | | | | | | | | | | | | | | | | | | | | | | A blkg (blkcg_gq) represents the relationship between a cgroup and request_queue. Each active policy has a pd (blkg_policy_data) on each blkg. The pd's were allocated by blkcg core and each policy could request to allocate extra space at the end by setting blkcg_policy->pd_size larger than the size of pd. This is a bit unusual but was done this way mostly to simplify error handling and all the existing use cases could be handled this way; however, this is becoming too restrictive now that percpu memory can be allocated without blocking. This introduces two new mandatory blkcg_policy methods - pd_alloc_fn() and pd_free_fn() - which are used to allocate and release pd for a given policy. As pd allocation is now done from policy side, it can simply allocate a larger area which embeds pd at the beginning. This change makes ->pd_size pointless. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: restructure blkg_policy_data allocation in blkcg_activate_policy()Tejun Heo2015-08-181-3/+0
| | | | | | | | | | | | | | | | | | When a policy gets activated, it needs to allocate and install its policy data on all existing blkg's (blkcg_gq's). Because blkg iteration is protected by a spinlock, it currently counts the total number of blkg's in the system, allocates the matching number of policy data on a list and installs them during a single iteration. This can be simplified by using speculative GFP_NOWAIT allocations while iterating and falling back to a preallocated policy data on failure. If the preallocated one has already been consumed, it releases the lock, preallocate with GFP_KERNEL and then restarts the iteration. This can be a bit more expensive than before but policy activation is a very cold path and shouldn't matter. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: remove unnecessary request_list->blkg NULL test in blk_put_rl()Tejun Heo2015-08-181-2/+1
| | | | | | | | | | Since ec13b1d6f0a0 ("blkcg: always create the blkcg_gq for the root blkcg"), a request_list always has its blkg associated. Drop unnecessary rl->blkg NULL test from blk_put_rl(). Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: fix blkcg_policy_data allocation bugTejun Heo2015-07-091-8/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | e48453c386f3 ("block, cgroup: implement policy-specific per-blkcg data") updated per-blkcg policy data to be dynamically allocated. When a policy is registered, its policy data aren't created. Instead, when the policy is activated on a queue, the policy data are allocated if there are blkg's (blkcg_gq's) which are attached to a given blkcg. This is buggy. Consider the following scenario. 1. A blkcg is created. No blkg's attached yet. 2. The policy is registered. No policy data is allocated. 3. The policy is activated on a queue. As the above blkcg doesn't have any blkg's, it won't allocate the matching blkcg_policy_data. 4. An IO is issued from the blkcg and blkg is created and the blkcg still doesn't have the matching policy data allocated. With cfq-iosched, this leads to an oops. It also doesn't free policy data on policy unregistration assuming that freeing of all policy data on blkcg destruction should take care of it; however, this also is incorrect. 1. A blkcg has policy data. 2. The policy gets unregistered but the policy data remains. 3. Another policy gets registered on the same slot. 4. Later, the new policy tries to allocate policy data on the previous blkcg but the slot is already occupied and gets skipped. The policy ends up operating on the policy data of the previous policy. There's no reason to manage blkcg_policy_data lazily. The reason we do lazy allocation of blkg's is that the number of all possible blkg's is the product of cgroups and block devices which can reach a surprising level. blkcg_policy_data is contrained by the number of cgroups and shouldn't be a problem. This patch makes blkcg_policy_data to be allocated for all existing blkcg's on policy registration and freed on unregistration and removes blkcg_policy_data handling from policy [de]activation paths. This makes that blkcg_policy_data are created and removed with the policy they belong to and fixes the above described problems. Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: e48453c386f3 ("block, cgroup: implement policy-specific per-blkcg data") Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Arianna Avanzini <avanzini.arianna@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: implement all_blkcgs listTejun Heo2015-07-091-0/+1
| | | | | | | | | | | Add all_blkcgs list goes through blkcg->all_blkcgs_node and is protected by blkcg_pol_mutex. This will be used to fix blkcg_policy_data allocation bug. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Arianna Avanzini <avanzini.arianna@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* Merge branch 'for-4.2/writeback' of git://git.kernel.dk/linux-blockLinus Torvalds2015-06-251-8/+32
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull cgroup writeback support from Jens Axboe: "This is the big pull request for adding cgroup writeback support. This code has been in development for a long time, and it has been simmering in for-next for a good chunk of this cycle too. This is one of those problems that has been talked about for at least half a decade, finally there's a solution and code to go with it. Also see last weeks writeup on LWN: http://lwn.net/Articles/648292/" * 'for-4.2/writeback' of git://git.kernel.dk/linux-block: (85 commits) writeback, blkio: add documentation for cgroup writeback support vfs, writeback: replace FS_CGROUP_WRITEBACK with SB_I_CGROUPWB writeback: do foreign inode detection iff cgroup writeback is enabled v9fs: fix error handling in v9fs_session_init() bdi: fix wrong error return value in cgwb_create() buffer: remove unusued 'ret' variable writeback: disassociate inodes from dying bdi_writebacks writeback: implement foreign cgroup inode bdi_writeback switching writeback: add lockdep annotation to inode_to_wb() writeback: use unlocked_inode_to_wb transaction in inode_congested() writeback: implement unlocked_inode_to_wb transaction and use it for stat updates writeback: implement [locked_]inode_to_wb_and_lock_list() writeback: implement foreign cgroup inode detection writeback: make writeback_control track the inode being written back writeback: relocate wb[_try]_get(), wb_put(), inode_{attach|detach}_wb() mm: vmscan: disable memcg direct reclaim stalling if cgroup writeback support is in use writeback: implement memcg writeback domain based throttling writeback: reset wb_domain->dirty_limit[_tstmp] when memcg domain size changes writeback: implement memcg wb_domain writeback: update wb_over_bg_thresh() to use wb_domain aware operations ...
* writeback, blkcg: associate each blkcg_gq with the corresponding ↵Tejun Heo2015-06-021-0/+6
| | | | | | | | | | | | | | | | | | | | | bdi_writeback_congested A blkg (blkcg_gq) can be congested and decongested independently from other blkgs on the same request_queue. Accordingly, for cgroup writeback support, the congestion status at bdi (backing_dev_info) should be split and updated separately from matching blkg's. This patch prepares by adding blkg->wb_congested and associating a blkg with its matching per-blkcg bdi_writeback_congested on creation. v2: Updated to associate bdi_writeback_congested instead of bdi_writeback. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* writeback: make backing_dev_info host cgroup-specific bdi_writebacksTejun Heo2015-06-021-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For the planned cgroup writeback support, on each bdi (backing_dev_info), each memcg will be served by a separate wb (bdi_writeback). This patch updates bdi so that a bdi can host multiple wbs (bdi_writebacks). On the default hierarchy, blkcg implicitly enables memcg. This allows using memcg's page ownership for attributing writeback IOs, and every memcg - blkcg combination can be served by its own wb by assigning a dedicated wb to each memcg. This means that there may be multiple wb's of a bdi mapped to the same blkcg. As congested state is per blkcg - bdi combination, those wb's should share the same congested state. This is achieved by tracking congested state via bdi_writeback_congested structs which are keyed by blkcg. bdi->wb remains unchanged and will keep serving the root cgroup. cgwb's (cgroup wb's) for non-root cgroups are created on-demand or looked up while dirtying an inode according to the memcg of the page being dirtied or current task. Each cgwb is indexed on bdi->cgwb_tree by its memcg id. Once an inode is associated with its wb, it can be retrieved using inode_to_wb(). Currently, none of the filesystems has FS_CGROUP_WRITEBACK and all pages will keep being associated with bdi->wb. v3: inode_attach_wb() in account_page_dirtied() moved inside mapping_cap_account_dirty() block where it's known to be !NULL. Also, an unnecessary NULL check before kfree() removed. Both detected by the kbuild bot. v2: Updated so that wb association is per inode and wb is per memcg rather than blkcg. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: kbuild test robot <fengguang.wu@intel.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: implement task_get_blkcg_css()Tejun Heo2015-06-021-0/+12
| | | | | | | | | | Implement a wrapper around task_get_css() to acquire the blkcg css for a given task. The wrapper is necessary for cgroup writeback support as there will be places outside blkcg proper trying to acquire blkcg_css and blkio_cgrp_id will be undefined when !CONFIG_BLK_CGROUP. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: add blkcg_root_cssTejun Heo2015-06-021-0/+3
| | | | | | | | | | | | | | Add global constant blkcg_root_css which points to &blkcg_root.css. This will be used by cgroup writeback support. If blkcg is disabled, it's defined as ERR_PTR(-EINVAL). v2: The declarations moved to include/linux/blk-cgroup.h as suggested by Vivek. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Jens Axboe <axboe@fb.com>
* update !CONFIG_BLK_CGROUP dummies in include/linux/blk-cgroup.hTejun Heo2015-06-021-2/+5
| | | | | | | | | | | | | | | | The header file will be used more widely with the pending cgroup writeback support and the current set of dummy declarations aren't enough to handle different config combinations. Update as follows. * Drop the struct cgroup declaration. None of the dummy defs need it. * Define blkcg as an empty struct instead of just declaring it. * Wrap dummy function defs in CONFIG_BLOCK. Some functions use block data types and none of them are to be used w/o block enabled. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkcg: move block/blk-cgroup.h to include/linux/blk-cgroup.hTejun Heo2015-06-021-0/+603
cgroup aware writeback support will require exposing some of blkcg details. In preprataion, move block/blk-cgroup.h to include/linux/blk-cgroup.h. This patch is pure file move. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
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