linux_dsm_epyc7002/include/linux/blk-cgroup.h

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License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 21:07:57 +07:00
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _BLK_CGROUP_H
#define _BLK_CGROUP_H
/*
* Common Block IO controller cgroup interface
*
* Based on ideas and code from CFQ, CFS and BFQ:
* Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
*
* Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
* Paolo Valente <paolo.valente@unimore.it>
*
* Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
* Nauman Rafique <nauman@google.com>
*/
#include <linux/cgroup.h>
#include <linux/percpu_counter.h>
#include <linux/seq_file.h>
#include <linux/radix-tree.h>
blkcg: implement per-blkg request allocation 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>
2012-06-27 05:05:44 +07:00
#include <linux/blkdev.h>
blkcg: fix use-after-free in __blkg_release_rcu() by making blkcg_gq refcnt 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>
2014-06-20 04:42:57 +07:00
#include <linux/atomic.h>
#include <linux/kthread.h>
/* percpu_counter batch for blkg_[rw]stats, per-cpu drift doesn't matter */
#define BLKG_STAT_CPU_BATCH (INT_MAX / 2)
/* Max limits for throttle policy */
#define THROTL_IOPS_MAX UINT_MAX
#ifdef CONFIG_BLK_CGROUP
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
enum blkg_rwstat_type {
BLKG_RWSTAT_READ,
BLKG_RWSTAT_WRITE,
BLKG_RWSTAT_SYNC,
BLKG_RWSTAT_ASYNC,
BLKG_RWSTAT_DISCARD,
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
BLKG_RWSTAT_NR,
BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR,
};
struct blkcg_gq;
struct blkcg {
struct cgroup_subsys_state css;
spinlock_t lock;
struct radix_tree_root blkg_tree;
struct blkcg_gq __rcu *blkg_hint;
struct hlist_head blkg_list;
struct blkcg_policy_data *cpd[BLKCG_MAX_POLS];
writeback: make backing_dev_info host cgroup-specific bdi_writebacks 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>
2015-05-23 04:13:37 +07:00
struct list_head all_blkcgs_node;
writeback: make backing_dev_info host cgroup-specific bdi_writebacks 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>
2015-05-23 04:13:37 +07:00
#ifdef CONFIG_CGROUP_WRITEBACK
struct list_head cgwb_list;
#endif
};
/*
* blkg_[rw]stat->aux_cnt is excluded for local stats but included for
* recursive. Used to carry stats of dead children, and, for blkg_rwstat,
* to carry result values from read and sum operations.
*/
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
struct blkg_stat {
struct percpu_counter cpu_cnt;
atomic64_t aux_cnt;
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
};
struct blkg_rwstat {
struct percpu_counter cpu_cnt[BLKG_RWSTAT_NR];
atomic64_t aux_cnt[BLKG_RWSTAT_NR];
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
};
/*
* A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
* request_queue (q). This is used by blkcg policies which need to track
* information per blkcg - q pair.
*
* There can be multiple active blkcg policies and each blkg:policy pair is
* represented by a blkg_policy_data which is allocated and freed by each
* policy's pd_alloc/free_fn() methods. A policy can allocate private data
* area by allocating larger data structure which embeds blkg_policy_data
* at the beginning.
*/
struct blkg_policy_data {
/* the blkg and policy id this per-policy data belongs to */
struct blkcg_gq *blkg;
int plid;
};
block, cgroup: implement policy-specific per-blkcg data The block IO (blkio) controller enables the block layer to provide service guarantees in a hierarchical fashion. Specifically, service guarantees are provided by registered request-accounting policies. As of now, a proportional-share and a throttling policy are available. They are implemented, respectively, by the CFQ I/O scheduler and the blk-throttle subsystem. Unfortunately, as for adding new policies, the current implementation of the block IO controller is only halfway ready to allow new policies to be plugged in. This commit provides a solution to make the block IO controller fully ready to handle new policies. In what follows, we first describe briefly the current state, and then list the changes made by this commit. The throttling policy does not need any per-cgroup information to perform its task. In contrast, the proportional share policy uses, for each cgroup, both the weight assigned by the user to the cgroup, and a set of dynamically- computed weights, one for each device. The first, user-defined weight is stored in the blkcg data structure: the block IO controller allocates a private blkcg data structure for each cgroup in the blkio cgroups hierarchy (regardless of which policy is active). In other words, the block IO controller internally mirrors the blkio cgroups with private blkcg data structures. On the other hand, for each cgroup and device, the corresponding dynamically- computed weight is maintained in the following, different way. For each device, the block IO controller keeps a private blkcg_gq structure for each cgroup in blkio. In other words, block IO also keeps one private mirror copy of the blkio cgroups hierarchy for each device, made of blkcg_gq structures. Each blkcg_gq structure keeps per-policy information in a generic array of dynamically-allocated 'dedicated' data structures, one for each registered policy (so currently the array contains two elements). To be inserted into the generic array, each dedicated data structure embeds a generic blkg_policy_data structure. Consider now the array contained in the blkcg_gq structure corresponding to a given pair of cgroup and device: one of the elements of the array contains the dedicated data structure for the proportional-share policy, and this dedicated data structure contains the dynamically-computed weight for that pair of cgroup and device. The generic strategy adopted for storing per-policy data in blkcg_gq structures is already capable of handling new policies, whereas the one adopted with blkcg structures is not, because per-policy data are hard-coded in the blkcg structures themselves (currently only data related to the proportional- share policy). This commit addresses the above issues through the following changes: . It generalizes blkcg structures so that per-policy data are stored in the same way as in blkcg_gq structures. Specifically, it lets also the blkcg structure store per-policy data in a generic array of dynamically-allocated dedicated data structures. We will refer to these data structures as blkcg dedicated data structures, to distinguish them from the dedicated data structures inserted in the generic arrays kept by blkcg_gq structures. To allow blkcg dedicated data structures to be inserted in the generic array inside a blkcg structure, this commit also introduces a new blkcg_policy_data structure, which is the equivalent of blkg_policy_data for blkcg dedicated data structures. . It adds to the blkcg_policy structure, i.e., to the descriptor of a policy, a cpd_size field and a cpd_init field, to be initialized by the policy with, respectively, the size of the blkcg dedicated data structures, and the address of a constructor function for blkcg dedicated data structures. . It moves the CFQ-specific fields embedded in the blkcg data structure (i.e., the fields related to the proportional-share policy), into a new blkcg dedicated data structure called cfq_group_data. Signed-off-by: Paolo Valente <paolo.valente@unimore.it> Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-06 04:38:42 +07:00
/*
* Policies that need to keep per-blkcg data which is independent from any
* request_queue associated to it should implement cpd_alloc/free_fn()
* methods. A policy can allocate private data area by allocating larger
* data structure which embeds blkcg_policy_data at the beginning.
* cpd_init() is invoked to let each policy handle per-blkcg data.
block, cgroup: implement policy-specific per-blkcg data The block IO (blkio) controller enables the block layer to provide service guarantees in a hierarchical fashion. Specifically, service guarantees are provided by registered request-accounting policies. As of now, a proportional-share and a throttling policy are available. They are implemented, respectively, by the CFQ I/O scheduler and the blk-throttle subsystem. Unfortunately, as for adding new policies, the current implementation of the block IO controller is only halfway ready to allow new policies to be plugged in. This commit provides a solution to make the block IO controller fully ready to handle new policies. In what follows, we first describe briefly the current state, and then list the changes made by this commit. The throttling policy does not need any per-cgroup information to perform its task. In contrast, the proportional share policy uses, for each cgroup, both the weight assigned by the user to the cgroup, and a set of dynamically- computed weights, one for each device. The first, user-defined weight is stored in the blkcg data structure: the block IO controller allocates a private blkcg data structure for each cgroup in the blkio cgroups hierarchy (regardless of which policy is active). In other words, the block IO controller internally mirrors the blkio cgroups with private blkcg data structures. On the other hand, for each cgroup and device, the corresponding dynamically- computed weight is maintained in the following, different way. For each device, the block IO controller keeps a private blkcg_gq structure for each cgroup in blkio. In other words, block IO also keeps one private mirror copy of the blkio cgroups hierarchy for each device, made of blkcg_gq structures. Each blkcg_gq structure keeps per-policy information in a generic array of dynamically-allocated 'dedicated' data structures, one for each registered policy (so currently the array contains two elements). To be inserted into the generic array, each dedicated data structure embeds a generic blkg_policy_data structure. Consider now the array contained in the blkcg_gq structure corresponding to a given pair of cgroup and device: one of the elements of the array contains the dedicated data structure for the proportional-share policy, and this dedicated data structure contains the dynamically-computed weight for that pair of cgroup and device. The generic strategy adopted for storing per-policy data in blkcg_gq structures is already capable of handling new policies, whereas the one adopted with blkcg structures is not, because per-policy data are hard-coded in the blkcg structures themselves (currently only data related to the proportional- share policy). This commit addresses the above issues through the following changes: . It generalizes blkcg structures so that per-policy data are stored in the same way as in blkcg_gq structures. Specifically, it lets also the blkcg structure store per-policy data in a generic array of dynamically-allocated dedicated data structures. We will refer to these data structures as blkcg dedicated data structures, to distinguish them from the dedicated data structures inserted in the generic arrays kept by blkcg_gq structures. To allow blkcg dedicated data structures to be inserted in the generic array inside a blkcg structure, this commit also introduces a new blkcg_policy_data structure, which is the equivalent of blkg_policy_data for blkcg dedicated data structures. . It adds to the blkcg_policy structure, i.e., to the descriptor of a policy, a cpd_size field and a cpd_init field, to be initialized by the policy with, respectively, the size of the blkcg dedicated data structures, and the address of a constructor function for blkcg dedicated data structures. . It moves the CFQ-specific fields embedded in the blkcg data structure (i.e., the fields related to the proportional-share policy), into a new blkcg dedicated data structure called cfq_group_data. Signed-off-by: Paolo Valente <paolo.valente@unimore.it> Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-06 04:38:42 +07:00
*/
struct blkcg_policy_data {
/* the blkcg and policy id this per-policy data belongs to */
struct blkcg *blkcg;
block, cgroup: implement policy-specific per-blkcg data The block IO (blkio) controller enables the block layer to provide service guarantees in a hierarchical fashion. Specifically, service guarantees are provided by registered request-accounting policies. As of now, a proportional-share and a throttling policy are available. They are implemented, respectively, by the CFQ I/O scheduler and the blk-throttle subsystem. Unfortunately, as for adding new policies, the current implementation of the block IO controller is only halfway ready to allow new policies to be plugged in. This commit provides a solution to make the block IO controller fully ready to handle new policies. In what follows, we first describe briefly the current state, and then list the changes made by this commit. The throttling policy does not need any per-cgroup information to perform its task. In contrast, the proportional share policy uses, for each cgroup, both the weight assigned by the user to the cgroup, and a set of dynamically- computed weights, one for each device. The first, user-defined weight is stored in the blkcg data structure: the block IO controller allocates a private blkcg data structure for each cgroup in the blkio cgroups hierarchy (regardless of which policy is active). In other words, the block IO controller internally mirrors the blkio cgroups with private blkcg data structures. On the other hand, for each cgroup and device, the corresponding dynamically- computed weight is maintained in the following, different way. For each device, the block IO controller keeps a private blkcg_gq structure for each cgroup in blkio. In other words, block IO also keeps one private mirror copy of the blkio cgroups hierarchy for each device, made of blkcg_gq structures. Each blkcg_gq structure keeps per-policy information in a generic array of dynamically-allocated 'dedicated' data structures, one for each registered policy (so currently the array contains two elements). To be inserted into the generic array, each dedicated data structure embeds a generic blkg_policy_data structure. Consider now the array contained in the blkcg_gq structure corresponding to a given pair of cgroup and device: one of the elements of the array contains the dedicated data structure for the proportional-share policy, and this dedicated data structure contains the dynamically-computed weight for that pair of cgroup and device. The generic strategy adopted for storing per-policy data in blkcg_gq structures is already capable of handling new policies, whereas the one adopted with blkcg structures is not, because per-policy data are hard-coded in the blkcg structures themselves (currently only data related to the proportional- share policy). This commit addresses the above issues through the following changes: . It generalizes blkcg structures so that per-policy data are stored in the same way as in blkcg_gq structures. Specifically, it lets also the blkcg structure store per-policy data in a generic array of dynamically-allocated dedicated data structures. We will refer to these data structures as blkcg dedicated data structures, to distinguish them from the dedicated data structures inserted in the generic arrays kept by blkcg_gq structures. To allow blkcg dedicated data structures to be inserted in the generic array inside a blkcg structure, this commit also introduces a new blkcg_policy_data structure, which is the equivalent of blkg_policy_data for blkcg dedicated data structures. . It adds to the blkcg_policy structure, i.e., to the descriptor of a policy, a cpd_size field and a cpd_init field, to be initialized by the policy with, respectively, the size of the blkcg dedicated data structures, and the address of a constructor function for blkcg dedicated data structures. . It moves the CFQ-specific fields embedded in the blkcg data structure (i.e., the fields related to the proportional-share policy), into a new blkcg dedicated data structure called cfq_group_data. Signed-off-by: Paolo Valente <paolo.valente@unimore.it> Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-06 04:38:42 +07:00
int plid;
};
/* association between a blk cgroup and a request queue */
struct blkcg_gq {
/* Pointer to the associated request_queue */
struct request_queue *q;
struct list_head q_node;
struct hlist_node blkcg_node;
struct blkcg *blkcg;
/*
* Each blkg gets congested separately and the congestion state is
* propagated to the matching bdi_writeback_congested.
*/
struct bdi_writeback_congested *wb_congested;
/* all non-root blkcg_gq's are guaranteed to have access to parent */
struct blkcg_gq *parent;
blkcg: implement per-blkg request allocation 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>
2012-06-27 05:05:44 +07:00
/* request allocation list for this blkcg-q pair */
struct request_list rl;
/* reference count */
blkcg: fix use-after-free in __blkg_release_rcu() by making blkcg_gq refcnt 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>
2014-06-20 04:42:57 +07:00
atomic_t refcnt;
/* is this blkg online? protected by both blkcg and q locks */
bool online;
struct blkg_rwstat stat_bytes;
struct blkg_rwstat stat_ios;
struct blkg_policy_data *pd[BLKCG_MAX_POLS];
struct rcu_head rcu_head;
atomic_t use_delay;
atomic64_t delay_nsec;
atomic64_t delay_start;
u64 last_delay;
int last_use;
};
typedef struct blkcg_policy_data *(blkcg_pol_alloc_cpd_fn)(gfp_t gfp);
typedef void (blkcg_pol_init_cpd_fn)(struct blkcg_policy_data *cpd);
typedef void (blkcg_pol_free_cpd_fn)(struct blkcg_policy_data *cpd);
typedef void (blkcg_pol_bind_cpd_fn)(struct blkcg_policy_data *cpd);
typedef struct blkg_policy_data *(blkcg_pol_alloc_pd_fn)(gfp_t gfp, int node);
typedef void (blkcg_pol_init_pd_fn)(struct blkg_policy_data *pd);
typedef void (blkcg_pol_online_pd_fn)(struct blkg_policy_data *pd);
typedef void (blkcg_pol_offline_pd_fn)(struct blkg_policy_data *pd);
typedef void (blkcg_pol_free_pd_fn)(struct blkg_policy_data *pd);
typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkg_policy_data *pd);
typedef size_t (blkcg_pol_stat_pd_fn)(struct blkg_policy_data *pd, char *buf,
size_t size);
struct blkcg_policy {
int plid;
/* cgroup files for the policy */
blkcg: implement interface for the unified hierarchy 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>
2015-08-19 04:55:34 +07:00
struct cftype *dfl_cftypes;
struct cftype *legacy_cftypes;
/* operations */
blkcg_pol_alloc_cpd_fn *cpd_alloc_fn;
block, cgroup: implement policy-specific per-blkcg data The block IO (blkio) controller enables the block layer to provide service guarantees in a hierarchical fashion. Specifically, service guarantees are provided by registered request-accounting policies. As of now, a proportional-share and a throttling policy are available. They are implemented, respectively, by the CFQ I/O scheduler and the blk-throttle subsystem. Unfortunately, as for adding new policies, the current implementation of the block IO controller is only halfway ready to allow new policies to be plugged in. This commit provides a solution to make the block IO controller fully ready to handle new policies. In what follows, we first describe briefly the current state, and then list the changes made by this commit. The throttling policy does not need any per-cgroup information to perform its task. In contrast, the proportional share policy uses, for each cgroup, both the weight assigned by the user to the cgroup, and a set of dynamically- computed weights, one for each device. The first, user-defined weight is stored in the blkcg data structure: the block IO controller allocates a private blkcg data structure for each cgroup in the blkio cgroups hierarchy (regardless of which policy is active). In other words, the block IO controller internally mirrors the blkio cgroups with private blkcg data structures. On the other hand, for each cgroup and device, the corresponding dynamically- computed weight is maintained in the following, different way. For each device, the block IO controller keeps a private blkcg_gq structure for each cgroup in blkio. In other words, block IO also keeps one private mirror copy of the blkio cgroups hierarchy for each device, made of blkcg_gq structures. Each blkcg_gq structure keeps per-policy information in a generic array of dynamically-allocated 'dedicated' data structures, one for each registered policy (so currently the array contains two elements). To be inserted into the generic array, each dedicated data structure embeds a generic blkg_policy_data structure. Consider now the array contained in the blkcg_gq structure corresponding to a given pair of cgroup and device: one of the elements of the array contains the dedicated data structure for the proportional-share policy, and this dedicated data structure contains the dynamically-computed weight for that pair of cgroup and device. The generic strategy adopted for storing per-policy data in blkcg_gq structures is already capable of handling new policies, whereas the one adopted with blkcg structures is not, because per-policy data are hard-coded in the blkcg structures themselves (currently only data related to the proportional- share policy). This commit addresses the above issues through the following changes: . It generalizes blkcg structures so that per-policy data are stored in the same way as in blkcg_gq structures. Specifically, it lets also the blkcg structure store per-policy data in a generic array of dynamically-allocated dedicated data structures. We will refer to these data structures as blkcg dedicated data structures, to distinguish them from the dedicated data structures inserted in the generic arrays kept by blkcg_gq structures. To allow blkcg dedicated data structures to be inserted in the generic array inside a blkcg structure, this commit also introduces a new blkcg_policy_data structure, which is the equivalent of blkg_policy_data for blkcg dedicated data structures. . It adds to the blkcg_policy structure, i.e., to the descriptor of a policy, a cpd_size field and a cpd_init field, to be initialized by the policy with, respectively, the size of the blkcg dedicated data structures, and the address of a constructor function for blkcg dedicated data structures. . It moves the CFQ-specific fields embedded in the blkcg data structure (i.e., the fields related to the proportional-share policy), into a new blkcg dedicated data structure called cfq_group_data. Signed-off-by: Paolo Valente <paolo.valente@unimore.it> Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-06 04:38:42 +07:00
blkcg_pol_init_cpd_fn *cpd_init_fn;
blkcg_pol_free_cpd_fn *cpd_free_fn;
blkcg_pol_bind_cpd_fn *cpd_bind_fn;
blkcg_pol_alloc_pd_fn *pd_alloc_fn;
blkcg_pol_init_pd_fn *pd_init_fn;
blkcg_pol_online_pd_fn *pd_online_fn;
blkcg_pol_offline_pd_fn *pd_offline_fn;
blkcg_pol_free_pd_fn *pd_free_fn;
blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn;
blkcg_pol_stat_pd_fn *pd_stat_fn;
};
extern struct blkcg blkcg_root;
extern struct cgroup_subsys_state * const blkcg_root_css;
struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg,
struct request_queue *q, bool update_hint);
struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
struct request_queue *q);
int blkcg_init_queue(struct request_queue *q);
void blkcg_drain_queue(struct request_queue *q);
void blkcg_exit_queue(struct request_queue *q);
/* Blkio controller policy registration */
int blkcg_policy_register(struct blkcg_policy *pol);
void blkcg_policy_unregister(struct blkcg_policy *pol);
int blkcg_activate_policy(struct request_queue *q,
const struct blkcg_policy *pol);
void blkcg_deactivate_policy(struct request_queue *q,
const struct blkcg_policy *pol);
const char *blkg_dev_name(struct blkcg_gq *blkg);
void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
u64 (*prfill)(struct seq_file *,
struct blkg_policy_data *, int),
const struct blkcg_policy *pol, int data,
bool show_total);
u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
const struct blkg_rwstat *rwstat);
u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
int off);
int blkg_print_stat_bytes(struct seq_file *sf, void *v);
int blkg_print_stat_ios(struct seq_file *sf, void *v);
int blkg_print_stat_bytes_recursive(struct seq_file *sf, void *v);
int blkg_print_stat_ios_recursive(struct seq_file *sf, void *v);
u64 blkg_stat_recursive_sum(struct blkcg_gq *blkg,
struct blkcg_policy *pol, int off);
struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkcg_gq *blkg,
struct blkcg_policy *pol, int off);
struct blkg_conf_ctx {
struct gendisk *disk;
struct blkcg_gq *blkg;
char *body;
};
int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
char *input, struct blkg_conf_ctx *ctx);
void blkg_conf_finish(struct blkg_conf_ctx *ctx);
static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
{
return css ? container_of(css, struct blkcg, css) : NULL;
}
static inline struct blkcg *bio_blkcg(struct bio *bio)
{
struct cgroup_subsys_state *css;
if (bio && bio->bi_css)
return css_to_blkcg(bio->bi_css);
css = kthread_blkcg();
if (css)
return css_to_blkcg(css);
return css_to_blkcg(task_css(current, io_cgrp_id));
}
static inline bool blk_cgroup_congested(void)
{
struct cgroup_subsys_state *css;
bool ret = false;
rcu_read_lock();
css = kthread_blkcg();
if (!css)
css = task_css(current, io_cgrp_id);
while (css) {
if (atomic_read(&css->cgroup->congestion_count)) {
ret = true;
break;
}
css = css->parent;
}
rcu_read_unlock();
return ret;
}
/**
* bio_issue_as_root_blkg - see if this bio needs to be issued as root blkg
* @return: true if this bio needs to be submitted with the root blkg context.
*
* In order to avoid priority inversions we sometimes need to issue a bio as if
* it were attached to the root blkg, and then backcharge to the actual owning
* blkg. The idea is we do bio_blkcg() to look up the actual context for the
* bio and attach the appropriate blkg to the bio. Then we call this helper and
* if it is true run with the root blkg for that queue and then do any
* backcharging to the originating cgroup once the io is complete.
*/
static inline bool bio_issue_as_root_blkg(struct bio *bio)
{
return (bio->bi_opf & (REQ_META | REQ_SWAP)) != 0;
}
/**
* blkcg_parent - get the parent of a blkcg
* @blkcg: blkcg of interest
*
* Return the parent blkcg of @blkcg. Can be called anytime.
*/
static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
{
return css_to_blkcg(blkcg->css.parent);
}
/**
* __blkg_lookup - internal version of blkg_lookup()
* @blkcg: blkcg of interest
* @q: request_queue of interest
* @update_hint: whether to update lookup hint with the result or not
*
* This is internal version and shouldn't be used by policy
* implementations. Looks up blkgs for the @blkcg - @q pair regardless of
* @q's bypass state. If @update_hint is %true, the caller should be
* holding @q->queue_lock and lookup hint is updated on success.
*/
static inline struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg,
struct request_queue *q,
bool update_hint)
{
struct blkcg_gq *blkg;
if (blkcg == &blkcg_root)
return q->root_blkg;
blkg = rcu_dereference(blkcg->blkg_hint);
if (blkg && blkg->q == q)
return blkg;
return blkg_lookup_slowpath(blkcg, q, update_hint);
}
/**
* blkg_lookup - lookup blkg for the specified blkcg - q pair
* @blkcg: blkcg of interest
* @q: request_queue of interest
*
* Lookup blkg for the @blkcg - @q pair. This function should be called
* under RCU read lock and is guaranteed to return %NULL if @q is bypassing
* - see blk_queue_bypass_start() for details.
*/
static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg,
struct request_queue *q)
{
WARN_ON_ONCE(!rcu_read_lock_held());
if (unlikely(blk_queue_bypass(q)))
return NULL;
return __blkg_lookup(blkcg, q, false);
}
/**
* blk_queue_root_blkg - return blkg for the (blkcg_root, @q) pair
* @q: request_queue of interest
*
* Lookup blkg for @q at the root level. See also blkg_lookup().
*/
static inline struct blkcg_gq *blk_queue_root_blkg(struct request_queue *q)
{
return q->root_blkg;
}
/**
* blkg_to_pdata - get policy private data
* @blkg: blkg of interest
* @pol: policy of interest
*
* Return pointer to private data associated with the @blkg-@pol pair.
*/
static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
struct blkcg_policy *pol)
{
return blkg ? blkg->pd[pol->plid] : NULL;
}
block, cgroup: implement policy-specific per-blkcg data The block IO (blkio) controller enables the block layer to provide service guarantees in a hierarchical fashion. Specifically, service guarantees are provided by registered request-accounting policies. As of now, a proportional-share and a throttling policy are available. They are implemented, respectively, by the CFQ I/O scheduler and the blk-throttle subsystem. Unfortunately, as for adding new policies, the current implementation of the block IO controller is only halfway ready to allow new policies to be plugged in. This commit provides a solution to make the block IO controller fully ready to handle new policies. In what follows, we first describe briefly the current state, and then list the changes made by this commit. The throttling policy does not need any per-cgroup information to perform its task. In contrast, the proportional share policy uses, for each cgroup, both the weight assigned by the user to the cgroup, and a set of dynamically- computed weights, one for each device. The first, user-defined weight is stored in the blkcg data structure: the block IO controller allocates a private blkcg data structure for each cgroup in the blkio cgroups hierarchy (regardless of which policy is active). In other words, the block IO controller internally mirrors the blkio cgroups with private blkcg data structures. On the other hand, for each cgroup and device, the corresponding dynamically- computed weight is maintained in the following, different way. For each device, the block IO controller keeps a private blkcg_gq structure for each cgroup in blkio. In other words, block IO also keeps one private mirror copy of the blkio cgroups hierarchy for each device, made of blkcg_gq structures. Each blkcg_gq structure keeps per-policy information in a generic array of dynamically-allocated 'dedicated' data structures, one for each registered policy (so currently the array contains two elements). To be inserted into the generic array, each dedicated data structure embeds a generic blkg_policy_data structure. Consider now the array contained in the blkcg_gq structure corresponding to a given pair of cgroup and device: one of the elements of the array contains the dedicated data structure for the proportional-share policy, and this dedicated data structure contains the dynamically-computed weight for that pair of cgroup and device. The generic strategy adopted for storing per-policy data in blkcg_gq structures is already capable of handling new policies, whereas the one adopted with blkcg structures is not, because per-policy data are hard-coded in the blkcg structures themselves (currently only data related to the proportional- share policy). This commit addresses the above issues through the following changes: . It generalizes blkcg structures so that per-policy data are stored in the same way as in blkcg_gq structures. Specifically, it lets also the blkcg structure store per-policy data in a generic array of dynamically-allocated dedicated data structures. We will refer to these data structures as blkcg dedicated data structures, to distinguish them from the dedicated data structures inserted in the generic arrays kept by blkcg_gq structures. To allow blkcg dedicated data structures to be inserted in the generic array inside a blkcg structure, this commit also introduces a new blkcg_policy_data structure, which is the equivalent of blkg_policy_data for blkcg dedicated data structures. . It adds to the blkcg_policy structure, i.e., to the descriptor of a policy, a cpd_size field and a cpd_init field, to be initialized by the policy with, respectively, the size of the blkcg dedicated data structures, and the address of a constructor function for blkcg dedicated data structures. . It moves the CFQ-specific fields embedded in the blkcg data structure (i.e., the fields related to the proportional-share policy), into a new blkcg dedicated data structure called cfq_group_data. Signed-off-by: Paolo Valente <paolo.valente@unimore.it> Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-06 04:38:42 +07:00
static inline struct blkcg_policy_data *blkcg_to_cpd(struct blkcg *blkcg,
struct blkcg_policy *pol)
{
return blkcg ? blkcg->cpd[pol->plid] : NULL;
block, cgroup: implement policy-specific per-blkcg data The block IO (blkio) controller enables the block layer to provide service guarantees in a hierarchical fashion. Specifically, service guarantees are provided by registered request-accounting policies. As of now, a proportional-share and a throttling policy are available. They are implemented, respectively, by the CFQ I/O scheduler and the blk-throttle subsystem. Unfortunately, as for adding new policies, the current implementation of the block IO controller is only halfway ready to allow new policies to be plugged in. This commit provides a solution to make the block IO controller fully ready to handle new policies. In what follows, we first describe briefly the current state, and then list the changes made by this commit. The throttling policy does not need any per-cgroup information to perform its task. In contrast, the proportional share policy uses, for each cgroup, both the weight assigned by the user to the cgroup, and a set of dynamically- computed weights, one for each device. The first, user-defined weight is stored in the blkcg data structure: the block IO controller allocates a private blkcg data structure for each cgroup in the blkio cgroups hierarchy (regardless of which policy is active). In other words, the block IO controller internally mirrors the blkio cgroups with private blkcg data structures. On the other hand, for each cgroup and device, the corresponding dynamically- computed weight is maintained in the following, different way. For each device, the block IO controller keeps a private blkcg_gq structure for each cgroup in blkio. In other words, block IO also keeps one private mirror copy of the blkio cgroups hierarchy for each device, made of blkcg_gq structures. Each blkcg_gq structure keeps per-policy information in a generic array of dynamically-allocated 'dedicated' data structures, one for each registered policy (so currently the array contains two elements). To be inserted into the generic array, each dedicated data structure embeds a generic blkg_policy_data structure. Consider now the array contained in the blkcg_gq structure corresponding to a given pair of cgroup and device: one of the elements of the array contains the dedicated data structure for the proportional-share policy, and this dedicated data structure contains the dynamically-computed weight for that pair of cgroup and device. The generic strategy adopted for storing per-policy data in blkcg_gq structures is already capable of handling new policies, whereas the one adopted with blkcg structures is not, because per-policy data are hard-coded in the blkcg structures themselves (currently only data related to the proportional- share policy). This commit addresses the above issues through the following changes: . It generalizes blkcg structures so that per-policy data are stored in the same way as in blkcg_gq structures. Specifically, it lets also the blkcg structure store per-policy data in a generic array of dynamically-allocated dedicated data structures. We will refer to these data structures as blkcg dedicated data structures, to distinguish them from the dedicated data structures inserted in the generic arrays kept by blkcg_gq structures. To allow blkcg dedicated data structures to be inserted in the generic array inside a blkcg structure, this commit also introduces a new blkcg_policy_data structure, which is the equivalent of blkg_policy_data for blkcg dedicated data structures. . It adds to the blkcg_policy structure, i.e., to the descriptor of a policy, a cpd_size field and a cpd_init field, to be initialized by the policy with, respectively, the size of the blkcg dedicated data structures, and the address of a constructor function for blkcg dedicated data structures. . It moves the CFQ-specific fields embedded in the blkcg data structure (i.e., the fields related to the proportional-share policy), into a new blkcg dedicated data structure called cfq_group_data. Signed-off-by: Paolo Valente <paolo.valente@unimore.it> Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-06 04:38:42 +07:00
}
/**
* pdata_to_blkg - get blkg associated with policy private data
* @pd: policy private data of interest
*
* @pd is policy private data. Determine the blkg it's associated with.
*/
static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
{
return pd ? pd->blkg : NULL;
}
static inline struct blkcg *cpd_to_blkcg(struct blkcg_policy_data *cpd)
{
return cpd ? cpd->blkcg : NULL;
}
/**
* blkg_path - format cgroup path of blkg
* @blkg: blkg of interest
* @buf: target buffer
* @buflen: target buffer length
*
* Format the path of the cgroup of @blkg into @buf.
*/
static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
{
return cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
}
/**
* blkg_get - get a blkg reference
* @blkg: blkg to get
*
blkcg: fix use-after-free in __blkg_release_rcu() by making blkcg_gq refcnt 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>
2014-06-20 04:42:57 +07:00
* The caller should be holding an existing reference.
*/
static inline void blkg_get(struct blkcg_gq *blkg)
{
blkcg: fix use-after-free in __blkg_release_rcu() by making blkcg_gq refcnt 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>
2014-06-20 04:42:57 +07:00
WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
atomic_inc(&blkg->refcnt);
}
/**
* blkg_try_get - try and get a blkg reference
* @blkg: blkg to get
*
* This is for use when doing an RCU lookup of the blkg. We may be in the midst
* of freeing this blkg, so we can only use it if the refcnt is not zero.
*/
static inline struct blkcg_gq *blkg_try_get(struct blkcg_gq *blkg)
{
if (atomic_inc_not_zero(&blkg->refcnt))
return blkg;
return NULL;
}
void __blkg_release_rcu(struct rcu_head *rcu);
/**
* blkg_put - put a blkg reference
* @blkg: blkg to put
*/
static inline void blkg_put(struct blkcg_gq *blkg)
{
blkcg: fix use-after-free in __blkg_release_rcu() by making blkcg_gq refcnt 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>
2014-06-20 04:42:57 +07:00
WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
if (atomic_dec_and_test(&blkg->refcnt))
call_rcu(&blkg->rcu_head, __blkg_release_rcu);
}
/**
* blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
* @d_blkg: loop cursor pointing to the current descendant
2013-08-09 07:11:25 +07:00
* @pos_css: used for iteration
* @p_blkg: target blkg to walk descendants of
*
* Walk @c_blkg through the descendants of @p_blkg. Must be used with RCU
* read locked. If called under either blkcg or queue lock, the iteration
* is guaranteed to include all and only online blkgs. The caller may
2013-08-09 07:11:25 +07:00
* update @pos_css by calling css_rightmost_descendant() to skip subtree.
cgroup: make css_for_each_descendant() and friends include the origin css in 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>
2013-08-09 07:11:27 +07:00
* @p_blkg is included in the iteration and the first node to be visited.
*/
2013-08-09 07:11:25 +07:00
#define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg) \
css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css) \
if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css), \
(p_blkg)->q, false)))
/**
* blkg_for_each_descendant_post - post-order walk of a blkg's descendants
* @d_blkg: loop cursor pointing to the current descendant
2013-08-09 07:11:25 +07:00
* @pos_css: used for iteration
* @p_blkg: target blkg to walk descendants of
*
* Similar to blkg_for_each_descendant_pre() but performs post-order
cgroup: make css_for_each_descendant() and friends include the origin css in 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>
2013-08-09 07:11:27 +07:00
* traversal instead. Synchronization rules are the same. @p_blkg is
* included in the iteration and the last node to be visited.
*/
2013-08-09 07:11:25 +07:00
#define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg) \
css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css) \
if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css), \
(p_blkg)->q, false)))
blkcg: implement per-blkg request allocation 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>
2012-06-27 05:05:44 +07:00
/**
* blk_get_rl - get request_list to use
* @q: request_queue of interest
* @bio: bio which will be attached to the allocated request (may be %NULL)
*
* The caller wants to allocate a request from @q to use for @bio. Find
* the request_list to use and obtain a reference on it. Should be called
* under queue_lock. This function is guaranteed to return non-%NULL
* request_list.
*/
static inline struct request_list *blk_get_rl(struct request_queue *q,
struct bio *bio)
{
struct blkcg *blkcg;
struct blkcg_gq *blkg;
rcu_read_lock();
blkcg = bio_blkcg(bio);
/* bypass blkg lookup and use @q->root_rl directly for root */
if (blkcg == &blkcg_root)
goto root_rl;
/*
* Try to use blkg->rl. blkg lookup may fail under memory pressure
* or if either the blkcg or queue is going away. Fall back to
* root_rl in such cases.
*/
blkcg: consolidate blkg creation in blkcg_bio_issue_check() 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>
2015-08-19 04:55:20 +07:00
blkg = blkg_lookup(blkcg, q);
if (unlikely(!blkg))
blkcg: implement per-blkg request allocation 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>
2012-06-27 05:05:44 +07:00
goto root_rl;
blkg_get(blkg);
rcu_read_unlock();
return &blkg->rl;
root_rl:
rcu_read_unlock();
return &q->root_rl;
}
/**
* blk_put_rl - put request_list
* @rl: request_list to put
*
* Put the reference acquired by blk_get_rl(). Should be called under
* queue_lock.
*/
static inline void blk_put_rl(struct request_list *rl)
{
if (rl->blkg->blkcg != &blkcg_root)
blkcg: implement per-blkg request allocation 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>
2012-06-27 05:05:44 +07:00
blkg_put(rl->blkg);
}
/**
* blk_rq_set_rl - associate a request with a request_list
* @rq: request of interest
* @rl: target request_list
*
* Associate @rq with @rl so that accounting and freeing can know the
* request_list @rq came from.
*/
static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
{
rq->rl = rl;
}
/**
* blk_rq_rl - return the request_list a request came from
* @rq: request of interest
*
* Return the request_list @rq is allocated from.
*/
static inline struct request_list *blk_rq_rl(struct request *rq)
{
return rq->rl;
}
struct request_list *__blk_queue_next_rl(struct request_list *rl,
struct request_queue *q);
/**
* blk_queue_for_each_rl - iterate through all request_lists of a request_queue
*
* Should be used under queue_lock.
*/
#define blk_queue_for_each_rl(rl, q) \
for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
static inline int blkg_stat_init(struct blkg_stat *stat, gfp_t gfp)
block: Use u64_stats_init() to initialize seqcounts 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>
2013-11-13 10:42:14 +07:00
{
int ret;
ret = percpu_counter_init(&stat->cpu_cnt, 0, gfp);
if (ret)
return ret;
atomic64_set(&stat->aux_cnt, 0);
return 0;
}
static inline void blkg_stat_exit(struct blkg_stat *stat)
{
percpu_counter_destroy(&stat->cpu_cnt);
block: Use u64_stats_init() to initialize seqcounts 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>
2013-11-13 10:42:14 +07:00
}
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
/**
* blkg_stat_add - add a value to a blkg_stat
* @stat: target blkg_stat
* @val: value to add
*
* Add @val to @stat. The caller must ensure that IRQ on the same CPU
* don't re-enter this function for the same counter.
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
*/
static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
{
percpu_counter_add_batch(&stat->cpu_cnt, val, BLKG_STAT_CPU_BATCH);
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
}
/**
* blkg_stat_read - read the current value of a blkg_stat
* @stat: blkg_stat to read
*/
static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
{
return percpu_counter_sum_positive(&stat->cpu_cnt);
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
}
/**
* blkg_stat_reset - reset a blkg_stat
* @stat: blkg_stat to reset
*/
static inline void blkg_stat_reset(struct blkg_stat *stat)
{
percpu_counter_set(&stat->cpu_cnt, 0);
atomic64_set(&stat->aux_cnt, 0);
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
}
/**
* blkg_stat_add_aux - add a blkg_stat into another's aux count
* @to: the destination blkg_stat
* @from: the source
*
* Add @from's count including the aux one to @to's aux count.
*/
static inline void blkg_stat_add_aux(struct blkg_stat *to,
struct blkg_stat *from)
{
atomic64_add(blkg_stat_read(from) + atomic64_read(&from->aux_cnt),
&to->aux_cnt);
}
static inline int blkg_rwstat_init(struct blkg_rwstat *rwstat, gfp_t gfp)
block: Use u64_stats_init() to initialize seqcounts 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>
2013-11-13 10:42:14 +07:00
{
int i, ret;
for (i = 0; i < BLKG_RWSTAT_NR; i++) {
ret = percpu_counter_init(&rwstat->cpu_cnt[i], 0, gfp);
if (ret) {
while (--i >= 0)
percpu_counter_destroy(&rwstat->cpu_cnt[i]);
return ret;
}
atomic64_set(&rwstat->aux_cnt[i], 0);
}
return 0;
}
static inline void blkg_rwstat_exit(struct blkg_rwstat *rwstat)
{
int i;
for (i = 0; i < BLKG_RWSTAT_NR; i++)
percpu_counter_destroy(&rwstat->cpu_cnt[i]);
block: Use u64_stats_init() to initialize seqcounts 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>
2013-11-13 10:42:14 +07:00
}
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
/**
* blkg_rwstat_add - add a value to a blkg_rwstat
* @rwstat: target blkg_rwstat
* @op: REQ_OP and flags
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
* @val: value to add
*
* Add @val to @rwstat. The counters are chosen according to @rw. The
* caller is responsible for synchronizing calls to this function.
*/
static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
unsigned int op, uint64_t val)
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
{
struct percpu_counter *cnt;
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
if (op_is_discard(op))
cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_DISCARD];
else if (op_is_write(op))
cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_WRITE];
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
else
cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_READ];
percpu_counter_add_batch(cnt, val, BLKG_STAT_CPU_BATCH);
if (op_is_sync(op))
cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_SYNC];
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
else
cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_ASYNC];
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
percpu_counter_add_batch(cnt, val, BLKG_STAT_CPU_BATCH);
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
}
/**
* blkg_rwstat_read - read the current values of a blkg_rwstat
* @rwstat: blkg_rwstat to read
*
* Read the current snapshot of @rwstat and return it in the aux counts.
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
*/
static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
{
struct blkg_rwstat result;
int i;
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
for (i = 0; i < BLKG_RWSTAT_NR; i++)
atomic64_set(&result.aux_cnt[i],
percpu_counter_sum_positive(&rwstat->cpu_cnt[i]));
return result;
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
}
/**
* blkg_rwstat_total - read the total count of a blkg_rwstat
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
* @rwstat: blkg_rwstat to read
*
* Return the total count of @rwstat regardless of the IO direction. This
* function can be called without synchronization and takes care of u64
* atomicity.
*/
static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat)
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
{
struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
return atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
}
/**
* blkg_rwstat_reset - reset a blkg_rwstat
* @rwstat: blkg_rwstat to reset
*/
static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
{
int i;
for (i = 0; i < BLKG_RWSTAT_NR; i++) {
percpu_counter_set(&rwstat->cpu_cnt[i], 0);
atomic64_set(&rwstat->aux_cnt[i], 0);
}
blkcg: introduce blkg_stat and blkg_rwstat blkcg uses u64_stats_sync to avoid reading wrong u64 statistic values on 32bit archs and some stat counters have subtypes to distinguish read/writes and sync/async IOs. The stat code paths are confusing and involve a lot of going back and forth between blkcg core and specific policy implementations, and synchronization and subtype handling are open coded in blkcg core. This patch introduces struct blkg_stat and blkg_rwstat which, with accompanying operations, encapsulate stat updating and accessing with proper synchronization. blkg_stat is simple u64 counter with 64bit read-access protection. blkg_rwstat is the one with rw and [a]sync subcounters and takes @rw flags to distinguish IO subtypes (%REQ_WRITE and %REQ_SYNC) and replaces stat_sub_type indexed arrays. All counters in blkio_group_stats and blkio_group_stats_cpu are replaced with either blkg_stat or blkg_rwstat along with all users. This does add one u64_stats_sync per counter and increase stats_sync operations but they're empty/noops on 64bit archs and blkcg doesn't have too many counters, especially with DEBUG_BLK_CGROUP off. While the currently resulting code isn't necessarily simpler at the moment, this will enable further clean up of blkcg stats code. - BLKIO_STAT_{READ|WRITE|SYNC|ASYNC|TOTAL} renamed to BLKG_RWSTAT_{READ|WRITE|SYNC|ASYNC|TOTAL}. - blkg_stat_add() replaces blkio_add_stat() and blkio_check_and_dec_stat(). Note that BUG_ON() on underflow in the latter function no longer exists. It's *way* better to have underflowed stat counters than oopsing. - blkio_group_stats->dequeue is now a proper u64 stat counter instead of ulong. - reset_stats() updated to clear each stat counters individually and BLKG_STATS_DEBUG_CLEAR_{START|SIZE} are removed. - Some functions reconstruct rw flags from direction and sync booleans. This will be removed by future patches. Signed-off-by: Tejun Heo <tj@kernel.org>
2012-04-02 04:38:42 +07:00
}
/**
* blkg_rwstat_add_aux - add a blkg_rwstat into another's aux count
* @to: the destination blkg_rwstat
* @from: the source
*
* Add @from's count including the aux one to @to's aux count.
*/
static inline void blkg_rwstat_add_aux(struct blkg_rwstat *to,
struct blkg_rwstat *from)
{
u64 sum[BLKG_RWSTAT_NR];
int i;
for (i = 0; i < BLKG_RWSTAT_NR; i++)
sum[i] = percpu_counter_sum_positive(&from->cpu_cnt[i]);
for (i = 0; i < BLKG_RWSTAT_NR; i++)
atomic64_add(sum[i] + atomic64_read(&from->aux_cnt[i]),
&to->aux_cnt[i]);
}
blkcg: consolidate blkg creation in blkcg_bio_issue_check() 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>
2015-08-19 04:55:20 +07:00
#ifdef CONFIG_BLK_DEV_THROTTLING
extern bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
struct bio *bio);
#else
static inline bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
struct bio *bio) { return false; }
#endif
static inline bool blkcg_bio_issue_check(struct request_queue *q,
struct bio *bio)
{
struct blkcg *blkcg;
struct blkcg_gq *blkg;
bool throtl = false;
rcu_read_lock();
blkcg = bio_blkcg(bio);
/* associate blkcg if bio hasn't attached one */
bio_associate_blkcg(bio, &blkcg->css);
blkcg: consolidate blkg creation in blkcg_bio_issue_check() 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>
2015-08-19 04:55:20 +07:00
blkg = blkg_lookup(blkcg, q);
if (unlikely(!blkg)) {
spin_lock_irq(q->queue_lock);
blkg = blkg_lookup_create(blkcg, q);
if (IS_ERR(blkg))
blkg = NULL;
spin_unlock_irq(q->queue_lock);
}
throtl = blk_throtl_bio(q, blkg, bio);
if (!throtl) {
blkg = blkg ?: q->root_blkg;
/*
* If the bio is flagged with BIO_QUEUE_ENTERED it means this
* is a split bio and we would have already accounted for the
* size of the bio.
*/
if (!bio_flagged(bio, BIO_QUEUE_ENTERED))
blkg_rwstat_add(&blkg->stat_bytes, bio->bi_opf,
bio->bi_iter.bi_size);
blkg_rwstat_add(&blkg->stat_ios, bio->bi_opf, 1);
}
blkcg: consolidate blkg creation in blkcg_bio_issue_check() 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>
2015-08-19 04:55:20 +07:00
rcu_read_unlock();
return !throtl;
}
static inline void blkcg_use_delay(struct blkcg_gq *blkg)
{
if (atomic_add_return(1, &blkg->use_delay) == 1)
atomic_inc(&blkg->blkcg->css.cgroup->congestion_count);
}
static inline int blkcg_unuse_delay(struct blkcg_gq *blkg)
{
int old = atomic_read(&blkg->use_delay);
if (old == 0)
return 0;
/*
* We do this song and dance because we can race with somebody else
* adding or removing delay. If we just did an atomic_dec we'd end up
* negative and we'd already be in trouble. We need to subtract 1 and
* then check to see if we were the last delay so we can drop the
* congestion count on the cgroup.
*/
while (old) {
int cur = atomic_cmpxchg(&blkg->use_delay, old, old - 1);
if (cur == old)
break;
old = cur;
}
if (old == 0)
return 0;
if (old == 1)
atomic_dec(&blkg->blkcg->css.cgroup->congestion_count);
return 1;
}
static inline void blkcg_clear_delay(struct blkcg_gq *blkg)
{
int old = atomic_read(&blkg->use_delay);
if (!old)
return;
/* We only want 1 person clearing the congestion count for this blkg. */
while (old) {
int cur = atomic_cmpxchg(&blkg->use_delay, old, 0);
if (cur == old) {
atomic_dec(&blkg->blkcg->css.cgroup->congestion_count);
break;
}
old = cur;
}
}
void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta);
void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay);
void blkcg_maybe_throttle_current(void);
#else /* CONFIG_BLK_CGROUP */
struct blkcg {
};
struct blkg_policy_data {
};
block, cgroup: implement policy-specific per-blkcg data The block IO (blkio) controller enables the block layer to provide service guarantees in a hierarchical fashion. Specifically, service guarantees are provided by registered request-accounting policies. As of now, a proportional-share and a throttling policy are available. They are implemented, respectively, by the CFQ I/O scheduler and the blk-throttle subsystem. Unfortunately, as for adding new policies, the current implementation of the block IO controller is only halfway ready to allow new policies to be plugged in. This commit provides a solution to make the block IO controller fully ready to handle new policies. In what follows, we first describe briefly the current state, and then list the changes made by this commit. The throttling policy does not need any per-cgroup information to perform its task. In contrast, the proportional share policy uses, for each cgroup, both the weight assigned by the user to the cgroup, and a set of dynamically- computed weights, one for each device. The first, user-defined weight is stored in the blkcg data structure: the block IO controller allocates a private blkcg data structure for each cgroup in the blkio cgroups hierarchy (regardless of which policy is active). In other words, the block IO controller internally mirrors the blkio cgroups with private blkcg data structures. On the other hand, for each cgroup and device, the corresponding dynamically- computed weight is maintained in the following, different way. For each device, the block IO controller keeps a private blkcg_gq structure for each cgroup in blkio. In other words, block IO also keeps one private mirror copy of the blkio cgroups hierarchy for each device, made of blkcg_gq structures. Each blkcg_gq structure keeps per-policy information in a generic array of dynamically-allocated 'dedicated' data structures, one for each registered policy (so currently the array contains two elements). To be inserted into the generic array, each dedicated data structure embeds a generic blkg_policy_data structure. Consider now the array contained in the blkcg_gq structure corresponding to a given pair of cgroup and device: one of the elements of the array contains the dedicated data structure for the proportional-share policy, and this dedicated data structure contains the dynamically-computed weight for that pair of cgroup and device. The generic strategy adopted for storing per-policy data in blkcg_gq structures is already capable of handling new policies, whereas the one adopted with blkcg structures is not, because per-policy data are hard-coded in the blkcg structures themselves (currently only data related to the proportional- share policy). This commit addresses the above issues through the following changes: . It generalizes blkcg structures so that per-policy data are stored in the same way as in blkcg_gq structures. Specifically, it lets also the blkcg structure store per-policy data in a generic array of dynamically-allocated dedicated data structures. We will refer to these data structures as blkcg dedicated data structures, to distinguish them from the dedicated data structures inserted in the generic arrays kept by blkcg_gq structures. To allow blkcg dedicated data structures to be inserted in the generic array inside a blkcg structure, this commit also introduces a new blkcg_policy_data structure, which is the equivalent of blkg_policy_data for blkcg dedicated data structures. . It adds to the blkcg_policy structure, i.e., to the descriptor of a policy, a cpd_size field and a cpd_init field, to be initialized by the policy with, respectively, the size of the blkcg dedicated data structures, and the address of a constructor function for blkcg dedicated data structures. . It moves the CFQ-specific fields embedded in the blkcg data structure (i.e., the fields related to the proportional-share policy), into a new blkcg dedicated data structure called cfq_group_data. Signed-off-by: Paolo Valente <paolo.valente@unimore.it> Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-06 04:38:42 +07:00
struct blkcg_policy_data {
};
struct blkcg_gq {
};
struct blkcg_policy {
};
#define blkcg_root_css ((struct cgroup_subsys_state *)ERR_PTR(-EINVAL))
static inline void blkcg_maybe_throttle_current(void) { }
static inline bool blk_cgroup_congested(void) { return false; }
#ifdef CONFIG_BLOCK
static inline void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay) { }
static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
static inline struct blkcg_gq *blk_queue_root_blkg(struct request_queue *q)
{ return NULL; }
static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
static inline void blkcg_drain_queue(struct request_queue *q) { }
static inline void blkcg_exit_queue(struct request_queue *q) { }
static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
static inline int blkcg_activate_policy(struct request_queue *q,
const struct blkcg_policy *pol) { return 0; }
static inline void blkcg_deactivate_policy(struct request_queue *q,
const struct blkcg_policy *pol) { }
static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
blkcg: implement per-blkg request allocation 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>
2012-06-27 05:05:44 +07:00
static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
struct blkcg_policy *pol) { return NULL; }
static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
static inline void blkg_get(struct blkcg_gq *blkg) { }
static inline void blkg_put(struct blkcg_gq *blkg) { }
blkcg: implement per-blkg request allocation 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>
2012-06-27 05:05:44 +07:00
static inline struct request_list *blk_get_rl(struct request_queue *q,
struct bio *bio) { return &q->root_rl; }
static inline void blk_put_rl(struct request_list *rl) { }
static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
blkcg: consolidate blkg creation in blkcg_bio_issue_check() 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>
2015-08-19 04:55:20 +07:00
static inline bool blkcg_bio_issue_check(struct request_queue *q,
struct bio *bio) { return true; }
blkcg: implement per-blkg request allocation 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>
2012-06-27 05:05:44 +07:00
#define blk_queue_for_each_rl(rl, q) \
for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
#endif /* CONFIG_BLOCK */
#endif /* CONFIG_BLK_CGROUP */
#endif /* _BLK_CGROUP_H */