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path: root/block/elevator.c
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2017-03-02block: don't call ioc_exit_icq() with the queue lock held for blk-mqJens Axboe1-2/+0
For legacy scheduling, we always call ioc_exit_icq() with both the ioc and queue lock held. This poses a problem for blk-mq with scheduling, since the queue lock isn't what we use in the scheduler. And since we don't need the queue lock held for ioc exit there, don't grab it and leave any extra locking up to the blk-mq scheduler. Reported-by: Paolo Valente <paolo.valente@linaro.org> Tested-by: Paolo Valente <paolo.valente@linaro.org> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-02-22block: get rid of blk-mq default scheduler choice Kconfig entriesJens Axboe1-6/+13
The wording in the entries were poor and not understandable by even deities. Kill the selection for default block scheduler, and impose a policy with sane defaults. Architected-by: Linus Torvalds <torvalds@linux-foundation.org> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-02-17Merge branch 'for-4.11/next' into for-4.11/linus-mergeJens Axboe1-7/+9
Signed-off-by: Jens Axboe <axboe@fb.com>
2017-02-14elevator: fix loading wrong elevator type for blk-mq devicesJens Axboe1-4/+5
The old elevator= boot parameter blindly attempts to load the same scheduler for mq and !mq devices, leading to a crash if we specify the wrong one. Ensure that we only apply this boot parameter to old !mq devices. Signed-off-by: Jens Axboe <axboe@fb.com>
2017-02-08block: enumify ELEVATOR_*_MERGEChristoph Hellwig1-4/+6
Switch these constants to an enum, and make let the compiler ensure that all callers of blk_try_merge and elv_merge handle all potential values. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-02-01blk-mq-debug: Avoid that sparse complains about req_flags_t usageBart Van Assche1-1/+1
Avoid that sparse reports the following complaints: block/elevator.c:541:29: warning: incorrect type in assignment (different base types) block/elevator.c:541:29: expected bool [unsigned] [usertype] next_sorted block/elevator.c:541:29: got restricted req_flags_t block/blk-mq-debugfs.c:92:54: warning: cast from restricted req_flags_t Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-01-31block: introduce blk_rq_is_passthroughChristoph Hellwig1-2/+2
This can be used to check for fs vs non-fs requests and basically removes all knowledge of BLOCK_PC specific from the block layer, as well as preparing for removing the cmd_type field in struct request. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2017-01-19elevator: fix unnecessary put of elevator in failure caseJens Axboe1-4/+0
We already checked that e is NULL, so no point in calling elevator_put() to free it. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Fixes: dc877dbd088f ("blk-mq-sched: add framework for MQ capable IO schedulers") Signed-off-by: Jens Axboe <axboe@fb.com>
2017-01-17blk-mq-sched: allow setting of default IO schedulerJens Axboe1-1/+7
Add Kconfig entries to manage what devices get assigned an MQ scheduler, and add a blk-mq flag for drivers to opt out of scheduling. The latter is useful for admin type queues that still allocate a blk-mq queue and tag set, but aren't use for normal IO. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Omar Sandoval <osandov@fb.com>
2017-01-17blk-mq-sched: add framework for MQ capable IO schedulersJens Axboe1-45/+159
This adds a set of hooks that intercepts the blk-mq path of allocating/inserting/issuing/completing requests, allowing us to develop a scheduler within that framework. We reuse the existing elevator scheduler API on the registration side, but augment that with the scheduler flagging support for the blk-mq interfce, and with a separate set of ops hooks for MQ devices. We split driver and scheduler tags, so we can run the scheduling independently of device queue depth. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Omar Sandoval <osandov@fb.com>
2017-01-17block: move existing elevator ops to unionJens Axboe1-30/+30
Prep patch for adding MQ ops as well, since doing anon unions with named initializers doesn't work on older compilers. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com> Reviewed-by: Omar Sandoval <osandov@fb.com>
2016-12-09elevator: make the rqhash helpers exportedJens Axboe1-4/+4
Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Hannes Reinecke <hare@suse.com>
2016-10-28block: better op and flags encodingChristoph Hellwig1-2/+2
Now that we don't need the common flags to overflow outside the range of a 32-bit type we can encode them the same way for both the bio and request fields. This in addition allows us to place the operation first (and make some room for more ops while we're at it) and to stop having to shift around the operation values. In addition this allows passing around only one value in the block layer instead of two (and eventuall also in the file systems, but we can do that later) and thus clean up a lot of code. Last but not least this allows decreasing the size of the cmd_flags field in struct request to 32-bits. Various functions passing this value could also be updated, but I'd like to avoid the churn for now. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-10-28block: split out request-only flags into a new namespaceChristoph Hellwig1-17/+15
A lot of the REQ_* flags are only used on struct requests, and only of use to the block layer and a few drivers that dig into struct request internals. This patch adds a new req_flags_t rq_flags field to struct request for them, and thus dramatically shrinks the number of common requests. It also removes the unfortunate situation where we have to fit the fields from the same enum into 32 bits for struct bio and 64 bits for struct request. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Shaun Tancheff <shaun.tancheff@seagate.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-08-16block: Fix secure eraseAdrian Hunter1-1/+1
Commit 288dab8a35a0 ("block: add a separate operation type for secure erase") split REQ_OP_SECURE_ERASE from REQ_OP_DISCARD without considering all the places REQ_OP_DISCARD was being used to mean either. Fix those. Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Fixes: 288dab8a35a0 ("block: add a separate operation type for secure erase") Signed-off-by: Jens Axboe <axboe@fb.com>
2016-07-20block: do not merge requests without consulting with io schedulerTahsin Erdogan1-11/+11
Before merging a bio into an existing request, io scheduler is called to get its approval first. However, the requests that come from a plug flush may get merged by block layer without consulting with io scheduler. In case of CFQ, this can cause fairness problems. For instance, if a request gets merged into a low weight cgroup's request, high weight cgroup now will depend on low weight cgroup to get scheduled. If high weigt cgroup needs that io request to complete before submitting more requests, then it will also lose its timeslice. Following script demonstrates the problem. Group g1 has a low weight, g2 and g3 have equal high weights but g2's requests are adjacent to g1's requests so they are subject to merging. Due to these merges, g2 gets poor disk time allocation. cat > cfq-merge-repro.sh << "EOF" #!/bin/bash set -e IO_ROOT=/mnt-cgroup/io mkdir -p $IO_ROOT if ! mount | grep -qw $IO_ROOT; then mount -t cgroup none -oblkio $IO_ROOT fi cd $IO_ROOT for i in g1 g2 g3; do if [ -d $i ]; then rmdir $i fi done mkdir g1 && echo 10 > g1/blkio.weight mkdir g2 && echo 495 > g2/blkio.weight mkdir g3 && echo 495 > g3/blkio.weight RUNTIME=10 (echo $BASHPID > g1/cgroup.procs && fio --readonly --name name1 --filename /dev/sdb \ --rw read --size 64k --bs 64k --time_based \ --runtime=$RUNTIME --offset=0k &> /dev/null)& (echo $BASHPID > g2/cgroup.procs && fio --readonly --name name1 --filename /dev/sdb \ --rw read --size 64k --bs 64k --time_based \ --runtime=$RUNTIME --offset=64k &> /dev/null)& (echo $BASHPID > g3/cgroup.procs && fio --readonly --name name1 --filename /dev/sdb \ --rw read --size 64k --bs 64k --time_based \ --runtime=$RUNTIME --offset=256k &> /dev/null)& sleep $((RUNTIME+1)) for i in g1 g2 g3; do echo ---- $i ---- cat $i/blkio.time done EOF # ./cfq-merge-repro.sh ---- g1 ---- 8:16 162 ---- g2 ---- 8:16 165 ---- g3 ---- 8:16 686 After applying the patch: # ./cfq-merge-repro.sh ---- g1 ---- 8:16 90 ---- g2 ---- 8:16 445 ---- g3 ---- 8:16 471 Signed-off-by: Tahsin Erdogan <tahsin@google.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2016-06-07block: prepare elevator to use REQ_OPs.Mike Christie1-4/+3
This patch converts the elevator code to use separate variables for the operation and flags, and to check req_op for the REQ_OP. Signed-off-by: Mike Christie <mchristi@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-10-21block: check bio_mergeable() early before mergingMing Lei1-1/+1
After bio splitting is introduced, one bio can be splitted and it is marked as NOMERGE because it is too fat to be merged, so check bio_mergeable() earlier to avoid to try to merge it unnecessarily. Signed-off-by: Ming Lei <ming.lei@canonical.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-25Merge branch 'for-4.2/writeback' of git://git.kernel.dk/linux-blockLinus Torvalds1-1/+1
Pull cgroup writeback support from Jens Axboe: "This is the big pull request for adding cgroup writeback support. This code has been in development for a long time, and it has been simmering in for-next for a good chunk of this cycle too. This is one of those problems that has been talked about for at least half a decade, finally there's a solution and code to go with it. Also see last weeks writeup on LWN: http://lwn.net/Articles/648292/" * 'for-4.2/writeback' of git://git.kernel.dk/linux-block: (85 commits) writeback, blkio: add documentation for cgroup writeback support vfs, writeback: replace FS_CGROUP_WRITEBACK with SB_I_CGROUPWB writeback: do foreign inode detection iff cgroup writeback is enabled v9fs: fix error handling in v9fs_session_init() bdi: fix wrong error return value in cgwb_create() buffer: remove unusued 'ret' variable writeback: disassociate inodes from dying bdi_writebacks writeback: implement foreign cgroup inode bdi_writeback switching writeback: add lockdep annotation to inode_to_wb() writeback: use unlocked_inode_to_wb transaction in inode_congested() writeback: implement unlocked_inode_to_wb transaction and use it for stat updates writeback: implement [locked_]inode_to_wb_and_lock_list() writeback: implement foreign cgroup inode detection writeback: make writeback_control track the inode being written back writeback: relocate wb[_try]_get(), wb_put(), inode_{attach|detach}_wb() mm: vmscan: disable memcg direct reclaim stalling if cgroup writeback support is in use writeback: implement memcg writeback domain based throttling writeback: reset wb_domain->dirty_limit[_tstmp] when memcg domain size changes writeback: implement memcg wb_domain writeback: update wb_over_bg_thresh() to use wb_domain aware operations ...
2015-06-25Merge branch 'for-4.2/core' of git://git.kernel.dk/linux-blockLinus Torvalds1-0/+2
Pull core block IO update from Jens Axboe: "Nothing really major in here, mostly a collection of smaller optimizations and cleanups, mixed with various fixes. In more detail, this contains: - Addition of policy specific data to blkcg for block cgroups. From Arianna Avanzini. - Various cleanups around command types from Christoph. - Cleanup of the suspend block I/O path from Christoph. - Plugging updates from Shaohua and Jeff Moyer, for blk-mq. - Eliminating atomic inc/dec of both remaining IO count and reference count in a bio. From me. - Fixes for SG gap and chunk size support for data-less (discards) IO, so we can merge these better. From me. - Small restructuring of blk-mq shared tag support, freeing drivers from iterating hardware queues. From Keith Busch. - A few cfq-iosched tweaks, from Tahsin Erdogan and me. Makes the IOPS mode the default for non-rotational storage" * 'for-4.2/core' of git://git.kernel.dk/linux-block: (35 commits) cfq-iosched: fix other locations where blkcg_to_cfqgd() can return NULL cfq-iosched: fix sysfs oops when attempting to read unconfigured weights cfq-iosched: move group scheduling functions under ifdef cfq-iosched: fix the setting of IOPS mode on SSDs blktrace: Add blktrace.c to BLOCK LAYER in MAINTAINERS file block, cgroup: implement policy-specific per-blkcg data block: Make CFQ default to IOPS mode on SSDs block: add blk_set_queue_dying() to blkdev.h blk-mq: Shared tag enhancements block: don't honor chunk sizes for data-less IO block: only honor SG gap prevention for merges that contain data block: fix returnvar.cocci warnings block, dm: don't copy bios for request clones block: remove management of bi_remaining when restoring original bi_end_io block: replace trylock with mutex_lock in blkdev_reread_part() block: export blkdev_reread_part() and __blkdev_reread_part() suspend: simplify block I/O handling block: collapse bio bit space block: remove unused BIO_RW_BLOCK and BIO_EOF flags block: remove BIO_EOPNOTSUPP ...
2015-06-10cfq-iosched: fix the setting of IOPS mode on SSDsJens Axboe1-0/+2
A previous commit wanted to make CFQ default to IOPS mode on non-rotational storage, however it did so when the queue was initialized and the non-rotational flag is only set later on in the probe. Add an elevator hook that gets called off the add_disk() path, at that point we know that feature probing has finished, and we can reliably check for the various flags that drivers can set. Fixes: 41c0126b ("block: Make CFQ default to IOPS mode on SSDs") Tested-by: Romain Francoise <romain@orebokech.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-06-02blkcg: move block/blk-cgroup.h to include/linux/blk-cgroup.hTejun Heo1-1/+1
cgroup aware writeback support will require exposing some of blkcg details. In preprataion, move block/blk-cgroup.h to include/linux/blk-cgroup.h. This patch is pure file move. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2015-04-23elevator: fix double release of elevator moduleChao Yu1-5/+1
Our issue is descripted in below call path: ->elevator_init ->elevator_init_fn ->{cfq,deadline,noop}_init_queue ->elevator_alloc ->kzalloc_node fail to call kzalloc_node and then put module in elevator_alloc; fail to call elevator_init_fn and then put module again in elevator_init. Remove elevator_put invoking in error path of elevator_alloc to avoid double release issue. Signed-off-by: Chao Yu <chao2.yu@samsung.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
2014-12-04block / PM: Replace CONFIG_PM_RUNTIME with CONFIG_PMRafael J. Wysocki1-1/+1
After commit b2b49ccbdd54 (PM: Kconfig: Set PM_RUNTIME if PM_SLEEP is selected) PM_RUNTIME is always set if PM is set, so #ifdef blocks depending on CONFIG_PM_RUNTIME may now be changed to depend on CONFIG_PM. Replace CONFIG_PM_RUNTIME with CONFIG_PM in the block device core. Reviewed-by: Aaron Lu <aaron.lu@intel.com> Acked-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2014-10-23block: fix wrong error return in elevator_init()Sudip Mukherjee1-1/+3
while compiling integer err was showing as a set but unused variable. elevator_init_fn can be either cfq_init_queue or deadline_init_queue or noop_init_queue. all three of these functions are returning -ENOMEM if they fail to allocate the queue. so we should actually be returning the error code rather than returning 0 always. Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org> Signed-off-by: Jens Axboe <axboe@fb.com>
2014-06-22Revert "block: add __init to elv_register"Jens Axboe1-1/+1
This reverts commit b5097e956a4d2919ee248d6481e4204c5568ed5c. The original commit is buggy, we do use the registration functions at runtime, for instance when loading IO schedulers through sysfs. Reported-by: Damien Wyart <damien.wyart@gmail.com>
2014-06-11block: remove elv_abort_queue and blk_abort_flushesChristoph Hellwig1-20/+0
elv_abort_queue has no callers, and blk_abort_flushes is only called by elv_abort_queue. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
2014-06-10block: add __init to elv_registerFabian Frederick1-1/+1
elv_register is only called by elevator init functions: __init cfq_init __init deadline_init __init noop_init Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Fabian Frederick <fabf@skynet.be> Signed-off-by: Jens Axboe <axboe@fb.com>
2014-04-09block: fix regression with block enabled taggingJens Axboe1-0/+2
Martin reported that his test system would not boot with current git, it oopsed with this: BUG: unable to handle kernel paging request at ffff88046c6c9e80 IP: [<ffffffff812971e0>] blk_queue_start_tag+0x90/0x150 PGD 1ddf067 PUD 1de2067 PMD 47fc7d067 PTE 800000046c6c9060 Oops: 0002 [#1] SMP DEBUG_PAGEALLOC Modules linked in: sd_mod lpfc(+) scsi_transport_fc scsi_tgt oracleasm rpcsec_gss_krb5 ipv6 igb dca i2c_algo_bit i2c_core hwmon CPU: 3 PID: 87 Comm: kworker/u17:1 Not tainted 3.14.0+ #246 Hardware name: Supermicro X9DRX+-F/X9DRX+-F, BIOS 3.00 07/09/2013 Workqueue: events_unbound async_run_entry_fn task: ffff8802743c2150 ti: ffff880273d02000 task.ti: ffff880273d02000 RIP: 0010:[<ffffffff812971e0>] [<ffffffff812971e0>] blk_queue_start_tag+0x90/0x150 RSP: 0018:ffff880273d03a58 EFLAGS: 00010092 RAX: ffff88046c6c9e78 RBX: ffff880077208e78 RCX: 00000000fffc8da6 RDX: 00000000fffc186d RSI: 0000000000000009 RDI: 00000000fffc8d9d RBP: ffff880273d03a88 R08: 0000000000000001 R09: ffff8800021c2410 R10: 0000000000000005 R11: 0000000000015b30 R12: ffff88046c5bb8a0 R13: ffff88046c5c0890 R14: 000000000000001e R15: 000000000000001e FS: 0000000000000000(0000) GS:ffff880277b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff88046c6c9e80 CR3: 00000000018f6000 CR4: 00000000000407e0 Stack: ffff880273d03a98 ffff880474b18800 0000000000000000 ffff880474157000 ffff88046c5c0890 ffff880077208e78 ffff880273d03ae8 ffffffff813b9e62 ffff880200000010 ffff880474b18968 ffff880474b18848 ffff88046c5c0cd8 Call Trace: [<ffffffff813b9e62>] scsi_request_fn+0xf2/0x510 [<ffffffff81293167>] __blk_run_queue+0x37/0x50 [<ffffffff8129ac43>] blk_execute_rq_nowait+0xb3/0x130 [<ffffffff8129ad24>] blk_execute_rq+0x64/0xf0 [<ffffffff8108d2b0>] ? bit_waitqueue+0xd0/0xd0 [<ffffffff813bba35>] scsi_execute+0xe5/0x180 [<ffffffff813bbe4a>] scsi_execute_req_flags+0x9a/0x110 [<ffffffffa01b1304>] sd_spinup_disk+0x94/0x460 [sd_mod] [<ffffffff81160000>] ? __unmap_hugepage_range+0x200/0x2f0 [<ffffffffa01b2b9a>] sd_revalidate_disk+0xaa/0x3f0 [sd_mod] [<ffffffffa01b2fb8>] sd_probe_async+0xd8/0x200 [sd_mod] [<ffffffff8107703f>] async_run_entry_fn+0x3f/0x140 [<ffffffff8106a1c5>] process_one_work+0x175/0x410 [<ffffffff8106b373>] worker_thread+0x123/0x400 [<ffffffff8106b250>] ? manage_workers+0x160/0x160 [<ffffffff8107104e>] kthread+0xce/0xf0 [<ffffffff81070f80>] ? kthread_freezable_should_stop+0x70/0x70 [<ffffffff815f0bac>] ret_from_fork+0x7c/0xb0 [<ffffffff81070f80>] ? kthread_freezable_should_stop+0x70/0x70 Code: 48 0f ab 11 72 db 48 81 4b 40 00 00 10 00 89 83 08 01 00 00 48 89 df 49 8b 04 24 48 89 1c d0 e8 f7 a8 ff ff 49 8b 85 28 05 00 00 <48> 89 58 08 48 89 03 49 8d 85 28 05 00 00 48 89 43 08 49 89 9d RIP [<ffffffff812971e0>] blk_queue_start_tag+0x90/0x150 RSP <ffff880273d03a58> CR2: ffff88046c6c9e80 Martin bisected and found this to be the problem patch; commit 6d113398dcf4dfcd9787a4ead738b186f7b7ff0f Author: Jan Kara <jack@suse.cz> Date: Mon Feb 24 16:39:54 2014 +0100 block: Stop abusing rq->csd.list in blk-softirq and the problem was immediately apparent. The patch states that it is safe to reuse queuelist at completion time, since it is no longer used. However, that is not true if a device is using block enabled tagging. If that is the case, then the queuelist is reused to keep track of busy tags. If a device also ended up using softirq completions, we'd reuse ->queuelist for the IPI handling while block tagging was still using it. Boom. Fix this by adding a new ipi_list list head, and share the memory used with the request hash table. The hash table is never used after the request is moved to the dispatch list, which happens long before any potential completion of the request. Add a new request bit for this, so we don't have cases that check rq->hash while it could potentially have been reused for the IPI completion. Reported-by: Martin K. Petersen <martin.petersen@oracle.com> Tested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Jens Axboe <axboe@fb.com>
2013-11-23block: Abstract out bvec iteratorKent Overstreet1-1/+1
Immutable biovecs are going to require an explicit iterator. To implement immutable bvecs, a later patch is going to add a bi_bvec_done member to this struct; for now, this patch effectively just renames things. Signed-off-by: Kent Overstreet <kmo@daterainc.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: "Ed L. Cashin" <ecashin@coraid.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Lars Ellenberg <drbd-dev@lists.linbit.com> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Matthew Wilcox <willy@linux.intel.com> Cc: Geoff Levand <geoff@infradead.org> Cc: Yehuda Sadeh <yehuda@inktank.com> Cc: Sage Weil <sage@inktank.com> Cc: Alex Elder <elder@inktank.com> Cc: ceph-devel@vger.kernel.org Cc: Joshua Morris <josh.h.morris@us.ibm.com> Cc: Philip Kelleher <pjk1939@linux.vnet.ibm.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Neil Brown <neilb@suse.de> Cc: Alasdair Kergon <agk@redhat.com> Cc: Mike Snitzer <snitzer@redhat.com> Cc: dm-devel@redhat.com Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: linux390@de.ibm.com Cc: Boaz Harrosh <bharrosh@panasas.com> Cc: Benny Halevy <bhalevy@tonian.com> Cc: "James E.J. Bottomley" <JBottomley@parallels.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Nicholas A. Bellinger" <nab@linux-iscsi.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Chris Mason <chris.mason@fusionio.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Jaegeuk Kim <jaegeuk.kim@samsung.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Dave Kleikamp <shaggy@kernel.org> Cc: Joern Engel <joern@logfs.org> Cc: Prasad Joshi <prasadjoshi.linux@gmail.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Ben Myers <bpm@sgi.com> Cc: xfs@oss.sgi.com Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Len Brown <len.brown@intel.com> Cc: Pavel Machek <pavel@ucw.cz> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com> Cc: Ben Hutchings <ben@decadent.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Guo Chao <yan@linux.vnet.ibm.com> Cc: Tejun Heo <tj@kernel.org> Cc: Asai Thambi S P <asamymuthupa@micron.com> Cc: Selvan Mani <smani@micron.com> Cc: Sam Bradshaw <sbradshaw@micron.com> Cc: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Cc: "Roger Pau Monné" <roger.pau@citrix.com> Cc: Jan Beulich <jbeulich@suse.com> Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com> Cc: Ian Campbell <Ian.Campbell@citrix.com> Cc: Sebastian Ott <sebott@linux.vnet.ibm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Jiang Liu <jiang.liu@huawei.com> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Jerome Marchand <jmarchand@redhat.com> Cc: Joe Perches <joe@perches.com> Cc: Peng Tao <tao.peng@emc.com> Cc: Andy Adamson <andros@netapp.com> Cc: fanchaoting <fanchaoting@cn.fujitsu.com> Cc: Jie Liu <jeff.liu@oracle.com> Cc: Sunil Mushran <sunil.mushran@gmail.com> Cc: "Martin K. Petersen" <martin.petersen@oracle.com> Cc: Namjae Jeon <namjae.jeon@samsung.com> Cc: Pankaj Kumar <pankaj.km@samsung.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Mel Gorman <mgorman@suse.de>6
2013-11-08elevator: acquire q->sysfs_lock in elevator_change()Tomoki Sekiyama1-2/+14
Add locking of q->sysfs_lock into elevator_change() (an exported function) to ensure it is held to protect q->elevator from elevator_init(), even if elevator_change() is called from non-sysfs paths. sysfs path (elv_iosched_store) uses __elevator_change(), non-locking version, as the lock is already taken by elv_iosched_store(). Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama@hds.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2013-11-08elevator: Fix a race in elevator switching and md device initializationTomoki Sekiyama1-0/+6
The soft lockup below happens at the boot time of the system using dm multipath and the udev rules to switch scheduler. [ 356.127001] BUG: soft lockup - CPU#3 stuck for 22s! [sh:483] [ 356.127001] RIP: 0010:[<ffffffff81072a7d>] [<ffffffff81072a7d>] lock_timer_base.isra.35+0x1d/0x50 ... [ 356.127001] Call Trace: [ 356.127001] [<ffffffff81073810>] try_to_del_timer_sync+0x20/0x70 [ 356.127001] [<ffffffff8118b08a>] ? kmem_cache_alloc_node_trace+0x20a/0x230 [ 356.127001] [<ffffffff810738b2>] del_timer_sync+0x52/0x60 [ 356.127001] [<ffffffff812ece22>] cfq_exit_queue+0x32/0xf0 [ 356.127001] [<ffffffff812c98df>] elevator_exit+0x2f/0x50 [ 356.127001] [<ffffffff812c9f21>] elevator_change+0xf1/0x1c0 [ 356.127001] [<ffffffff812caa50>] elv_iosched_store+0x20/0x50 [ 356.127001] [<ffffffff812d1d09>] queue_attr_store+0x59/0xb0 [ 356.127001] [<ffffffff812143f6>] sysfs_write_file+0xc6/0x140 [ 356.127001] [<ffffffff811a326d>] vfs_write+0xbd/0x1e0 [ 356.127001] [<ffffffff811a3ca9>] SyS_write+0x49/0xa0 [ 356.127001] [<ffffffff8164e899>] system_call_fastpath+0x16/0x1b This is caused by a race between md device initialization by multipathd and shell script to switch the scheduler using sysfs. - multipathd: SyS_ioctl -> do_vfs_ioctl -> dm_ctl_ioctl -> ctl_ioctl -> table_load -> dm_setup_md_queue -> blk_init_allocated_queue -> elevator_init q->elevator = elevator_alloc(q, e); // not yet initialized - sh -c 'echo deadline > /sys/$DEVPATH/queue/scheduler': elevator_switch (in the call trace above) struct elevator_queue *old = q->elevator; q->elevator = elevator_alloc(q, new_e); elevator_exit(old); // lockup! (*) - multipathd: (cont.) err = e->ops.elevator_init_fn(q); // init fails; q->elevator is modified (*) When del_timer_sync() is called, lock_timer_base() will loop infinitely while timer->base == NULL. In this case, as timer will never initialized, it results in lockup. This patch introduces acquisition of q->sysfs_lock around elevator_init() into blk_init_allocated_queue(), to provide mutual exclusion between initialization of the q->scheduler and switching of the scheduler. This should fix this bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=902012 Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama@hds.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2013-09-11block: Convert kmalloc_node(...GFP_ZERO...) to kzalloc_node(...)Joe Perches1-1/+1
Use the helper function instead of __GFP_ZERO. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2013-07-03elevator: Fix a race in elevator switchingJianpeng Ma1-20/+5
There's a race between elevator switching and normal io operation. Because the allocation of struct elevator_queue and struct elevator_data don't in a atomic operation.So there are have chance to use NULL ->elevator_data. For example: Thread A: Thread B blk_queu_bio elevator_switch spin_lock_irq(q->queue_block) elevator_alloc elv_merge elevator_init_fn Because call elevator_alloc, it can't hold queue_lock and the ->elevator_data is NULL.So at the same time, threadA call elv_merge and nedd some info of elevator_data.So the crash happened. Move the elevator_alloc into func elevator_init_fn, it make the operations in a atomic operation. Using the follow method can easy reproduce this bug 1:dd if=/dev/sdb of=/dev/null 2:while true;do echo noop > scheduler;echo deadline > scheduler;done The test method also use this method. Signed-off-by: Jianpeng Ma <majianpeng@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2013-03-22block: implement runtime pm strategyLin Ming1-0/+26
When a request is added: If device is suspended or is suspending and the request is not a PM request, resume the device. When the last request finishes: Call pm_runtime_mark_last_busy(). When pick a request: If device is resuming/suspending, then only PM request is allowed to go. The idea and API is designed by Alan Stern and described here: http://marc.info/?l=linux-scsi&m=133727953625963&w=2 Signed-off-by: Lin Ming <ming.m.lin@intel.com> Signed-off-by: Aaron Lu <aaron.lu@intel.com> Acked-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2013-02-28Merge branch 'for-3.9/core' of git://git.kernel.dk/linux-blockLinus Torvalds1-19/+4
Pull block IO core bits from Jens Axboe: "Below are the core block IO bits for 3.9. It was delayed a few days since my workstation kept crashing every 2-8h after pulling it into current -git, but turns out it is a bug in the new pstate code (divide by zero, will report separately). In any case, it contains: - The big cfq/blkcg update from Tejun and and Vivek. - Additional block and writeback tracepoints from Tejun. - Improvement of the should sort (based on queues) logic in the plug flushing. - _io() variants of the wait_for_completion() interface, using io_schedule() instead of schedule() to contribute to io wait properly. - Various little fixes. You'll get two trivial merge conflicts, which should be easy enough to fix up" Fix up the trivial conflicts due to hlist traversal cleanups (commit b67bfe0d42ca: "hlist: drop the node parameter from iterators"). * 'for-3.9/core' of git://git.kernel.dk/linux-block: (39 commits) block: remove redundant check to bd_openers() block: use i_size_write() in bd_set_size() cfq: fix lock imbalance with failed allocations drivers/block/swim3.c: fix null pointer dereference block: don't select PERCPU_RWSEM block: account iowait time when waiting for completion of IO request sched: add wait_for_completion_io[_timeout] writeback: add more tracepoints block: add block_{touch|dirty}_buffer tracepoint buffer: make touch_buffer() an exported function block: add @req to bio_{front|back}_merge tracepoints block: add missing block_bio_complete() tracepoint block: Remove should_sort judgement when flush blk_plug block,elevator: use new hashtable implementation cfq-iosched: add hierarchical cfq_group statistics cfq-iosched: collect stats from dead cfqgs cfq-iosched: separate out cfqg_stats_reset() from cfq_pd_reset_stats() blkcg: make blkcg_print_blkgs() grab q locks instead of blkcg lock block: RCU free request_queue blkcg: implement blkg_[rw]stat_recursive_sum() and blkg_[rw]stat_merge() ...
2013-02-27hlist: drop the node parameter from iteratorsSasha Levin1-2/+2
I'm not sure why, but the hlist for each entry iterators were conceived list_for_each_entry(pos, head, member) The hlist ones were greedy and wanted an extra parameter: hlist_for_each_entry(tpos, pos, head, member) Why did they need an extra pos parameter? I'm not quite sure. Not only they don't really need it, it also prevents the iterator from looking exactly like the list iterator, which is unfortunate. Besides the semantic patch, there was some manual work required: - Fix up the actual hlist iterators in linux/list.h - Fix up the declaration of other iterators based on the hlist ones. - A very small amount of places were using the 'node' parameter, this was modified to use 'obj->member' instead. - Coccinelle didn't handle the hlist_for_each_entry_safe iterator properly, so those had to be fixed up manually. The semantic patch which is mostly the work of Peter Senna Tschudin is here: @@ iterator name hlist_for_each_entry, hlist_for_each_entry_continue, hlist_for_each_entry_from, hlist_for_each_entry_rcu, hlist_for_each_entry_rcu_bh, hlist_for_each_entry_continue_rcu_bh, for_each_busy_worker, ax25_uid_for_each, ax25_for_each, inet_bind_bucket_for_each, sctp_for_each_hentry, sk_for_each, sk_for_each_rcu, sk_for_each_from, sk_for_each_safe, sk_for_each_bound, hlist_for_each_entry_safe, hlist_for_each_entry_continue_rcu, nr_neigh_for_each, nr_neigh_for_each_safe, nr_node_for_each, nr_node_for_each_safe, for_each_gfn_indirect_valid_sp, for_each_gfn_sp, for_each_host; type T; expression a,c,d,e; identifier b; statement S; @@ -T b; <+... when != b ( hlist_for_each_entry(a, - b, c, d) S | hlist_for_each_entry_continue(a, - b, c) S | hlist_for_each_entry_from(a, - b, c) S | hlist_for_each_entry_rcu(a, - b, c, d) S | hlist_for_each_entry_rcu_bh(a, - b, c, d) S | hlist_for_each_entry_continue_rcu_bh(a, - b, c) S | for_each_busy_worker(a, c, - b, d) S | ax25_uid_for_each(a, - b, c) S | ax25_for_each(a, - b, c) S | inet_bind_bucket_for_each(a, - b, c) S | sctp_for_each_hentry(a, - b, c) S | sk_for_each(a, - b, c) S | sk_for_each_rcu(a, - b, c) S | sk_for_each_from -(a, b) +(a) S + sk_for_each_from(a) S | sk_for_each_safe(a, - b, c, d) S | sk_for_each_bound(a, - b, c) S | hlist_for_each_entry_safe(a, - b, c, d, e) S | hlist_for_each_entry_continue_rcu(a, - b, c) S | nr_neigh_for_each(a, - b, c) S | nr_neigh_for_each_safe(a, - b, c, d) S | nr_node_for_each(a, - b, c) S | nr_node_for_each_safe(a, - b, c, d) S | - for_each_gfn_sp(a, c, d, b) S + for_each_gfn_sp(a, c, d) S | - for_each_gfn_indirect_valid_sp(a, c, d, b) S + for_each_gfn_indirect_valid_sp(a, c, d) S | for_each_host(a, - b, c) S | for_each_host_safe(a, - b, c, d) S | for_each_mesh_entry(a, - b, c, d) S ) ...+> [akpm@linux-foundation.org: drop bogus change from net/ipv4/raw.c] [akpm@linux-foundation.org: drop bogus hunk from net/ipv6/raw.c] [akpm@linux-foundation.org: checkpatch fixes] [akpm@linux-foundation.org: fix warnings] [akpm@linux-foudnation.org: redo intrusive kvm changes] Tested-by: Peter Senna Tschudin <peter.senna@gmail.com> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Gleb Natapov <gleb@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-01-22block: don't request module during elevator initTejun Heo1-7/+12
Block layer allows selecting an elevator which is built as a module to be selected as system default via kernel param "elevator=". This is achieved by automatically invoking request_module() whenever a new block device is initialized and the elevator is not available. This led to an interesting deadlock problem involving async and module init. Block device probing running off an async job invokes request_module(). While the module is being loaded, it performs async_synchronize_full() which ends up waiting for the async job which is already waiting for request_module() to finish, leading to deadlock. Invoking request_module() from deep in block device init path is already nasty in itself. It seems best to avoid these situations from the beginning by moving on-demand module loading out of block init path. The previous patch made sure that the default elevator module is loaded early during boot if available. This patch removes on-demand loading of the default elevator from elevator init path. As the module would have been loaded during boot, userland-visible behavior difference should be minimal. For more details, please refer to the following thread. http://thread.gmane.org/gmane.linux.kernel/1420814 v2: The bool parameter was named @request_module which conflicted with request_module(). This built okay w/ CONFIG_MODULES because request_module() was defined as a macro. W/o CONFIG_MODULES, it causes build breakage. Rename the parameter to @try_loading. Reported by Fengguang. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Alex Riesen <raa.lkml@gmail.com> Cc: Fengguang Wu <fengguang.wu@intel.com>
2013-01-18init, block: try to load default elevator module early during bootTejun Heo1-0/+16
This patch adds default module loading and uses it to load the default block elevator. During boot, it's called right after initramfs or initrd is made available and right before control is passed to userland. This ensures that as long as the modules are available in the usual places in initramfs, initrd or the root filesystem, the default modules are loaded as soon as possible. This will replace the on-demand elevator module loading from elevator init path. v2: Fixed build breakage when !CONFIG_BLOCK. Reported by kbuild test robot. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Alex Riesen <raa.lkml@gmail.com> Cc: Fengguang We <fengguang.wu@intel.com>
2013-01-11block,elevator: use new hashtable implementationSasha Levin1-19/+4
Switch elevator to use the new hashtable implementation. This reduces the amount of generic unrelated code in the elevator. This also removes the dymanic allocation of the hash table. The size of the table is constant so there's no point in paying the price of an extra dereference when accessing it. This patch depends on d9b482c ("hashtable: introduce a small and naive hashtable") which was merged in v3.6. Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-11-09block: recursive merge requestsShaohua Li1-4/+12
In a workload, thread 1 accesses a, a+2, ..., thread 2 accesses a+1, a+3,.... When the requests are flushed to queue, a and a+1 are merged to (a, a+1), a+2 and a+3 too to (a+2, a+3), but (a, a+1) and (a+2, a+3) aren't merged. If we do recursive merge for such interleave access, some workloads throughput get improvement. A recent worload I'm checking on is swap, below change boostes the throughput around 5% ~ 10%. Signed-off-by: Shaohua Li <shli@fusionio.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-09-20block: Clean up special command handling logicMartin K. Petersen1-4/+2
Remove special-casing of non-rw fs style requests (discard). The nomerge flags are consolidated in blk_types.h, and rq_mergeable() and bio_mergeable() have been modified to use them. bio_is_rw() is used in place of bio_has_data() a few places. This is done to to distinguish true reads and writes from other fs type requests that carry a payload (e.g. write same). Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Acked-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-04-20blkcg: implement per-queue policy activationTejun Heo1-2/+0
All blkcg policies were assumed to be enabled on all request_queues. Due to various implementation obstacles, during the recent blkcg core updates, this was temporarily implemented as shooting down all !root blkgs on elevator switch and policy [de]registration combined with half-broken in-place root blkg updates. In addition to being buggy and racy, this meant losing all blkcg configurations across those events. Now that blkcg is cleaned up enough, this patch replaces the temporary implementation with proper per-queue policy activation. Each blkcg policy should call the new blkcg_[de]activate_policy() to enable and disable the policy on a specific queue. blkcg_activate_policy() allocates and installs policy data for the policy for all existing blkgs. blkcg_deactivate_policy() does the reverse. If a policy is not enabled for a given queue, blkg printing / config functions skip the respective blkg for the queue. blkcg_activate_policy() also takes care of root blkg creation, and cfq_init_queue() and blk_throtl_init() are updated accordingly. This replaces blkcg_bypass_{start|end}() and update_root_blkg_pd() unnecessary. Dropped. v2: cfq_init_queue() was returning uninitialized @ret on root_group alloc failure if !CONFIG_CFQ_GROUP_IOSCHED. Fixed. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06block: implement bio_associate_current()Tejun Heo1-2/+3
IO scheduling and cgroup are tied to the issuing task via io_context and cgroup of %current. Unfortunately, there are cases where IOs need to be routed via a different task which makes scheduling and cgroup limit enforcement applied completely incorrectly. For example, all bios delayed by blk-throttle end up being issued by a delayed work item and get assigned the io_context of the worker task which happens to serve the work item and dumped to the default block cgroup. This is double confusing as bios which aren't delayed end up in the correct cgroup and makes using blk-throttle and cfq propio together impossible. Any code which punts IO issuing to another task is affected which is getting more and more common (e.g. btrfs). As both io_context and cgroup are firmly tied to task including userland visible APIs to manipulate them, it makes a lot of sense to match up tasks to bios. This patch implements bio_associate_current() which associates the specified bio with %current. The bio will record the associated ioc and blkcg at that point and block layer will use the recorded ones regardless of which task actually ends up issuing the bio. bio release puts the associated ioc and blkcg. It grabs and remembers ioc and blkcg instead of the task itself because task may already be dead by the time the bio is issued making ioc and blkcg inaccessible and those are all block layer cares about. elevator_set_req_fn() is updated such that the bio elvdata is being allocated for is available to the elevator. This doesn't update block cgroup policies yet. Further patches will implement the support. -v2: #ifdef CONFIG_BLK_CGROUP added around bio->bi_ioc dereference in rq_ioc() to fix build breakage. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Kent Overstreet <koverstreet@google.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06blkcg: unify blkg's for blkcg policiesTejun Heo1-3/+2
Currently, blkg is per cgroup-queue-policy combination. This is unnatural and leads to various convolutions in partially used duplicate fields in blkg, config / stat access, and general management of blkgs. This patch make blkg's per cgroup-queue and let them serve all policies. blkgs are now created and destroyed by blkcg core proper. This will allow further consolidation of common management logic into blkcg core and API with better defined semantics and layering. As a transitional step to untangle blkg management, elvswitch and policy [de]registration, all blkgs except the root blkg are being shot down during elvswitch and bypass. This patch adds blkg_root_update() to update root blkg in place on policy change. This is hacky and racy but should be good enough as interim step until we get locking simplified and switch over to proper in-place update for all blkgs. -v2: Root blkgs need to be updated on elvswitch too and blkg_alloc() comment wasn't updated according to the function change. Fixed. Both pointed out by Vivek. -v3: v2 updated blkg_destroy_all() to invoke update_root_blkg_pd() for all policies. This freed root pd during elvswitch before the last queue finished exiting and led to oops. Directly invoke update_root_blkg_pd() only on BLKIO_POLICY_PROP from cfq_exit_queue(). This also is closer to what will be done with proper in-place blkg update. Reported by Vivek. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06blkcg: let blkcg core manage per-queue blkg list and counterTejun Heo1-2/+3
With the previous patch to move blkg list heads and counters to request_queue and blkg, logic to manage them in both policies are almost identical and can be moved to blkcg core. This patch moves blkg link logic into blkg_lookup_create(), implements common blkg unlink code in blkg_destroy(), and updates blkg_destory_all() so that it's policy specific and can skip root group. The updated blkg_destroy_all() is now used to both clear queue for bypassing and elv switching, and release all blkgs on q exit. This patch introduces a race window where policy [de]registration may race against queue blkg clearing. This can only be a problem on cfq unload and shouldn't be a real problem in practice (and we have many other places where this race already exists). Future patches will remove these unlikely races. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06blkcg: shoot down blkio_groups on elevator switchTejun Heo1-0/+3
Elevator switch may involve changes to blkcg policies. Implement shoot down of blkio_groups. Combined with the previous bypass updates, the end goal is updating blkcg core such that it can ensure that blkcg's being affected become quiescent and don't have any per-blkg data hanging around before commencing any policy updates. Until queues are made aware of the policies that applies to them, as an interim step, all per-policy blkg data will be shot down. * blk-throtl doesn't need this change as it can't be disabled for a live queue; however, update it anyway as the scheduled blkg unification requires this behavior change. This means that blk-throtl configuration will be unnecessarily lost over elevator switch. This oddity will be removed after blkcg learns to associate individual policies with request_queues. * blk-throtl dosen't shoot down root_tg. This is to ease transition. Unified blkg will always have persistent root group and not shooting down root_tg for now eases transition to that point by avoiding having to update td->root_tg and is safe as blk-throtl can never be disabled -v2: Vivek pointed out that group list is not guaranteed to be empty on return from clear function if it raced cgroup removal and lost. Fix it by waiting a bit and retrying. This kludge will soon be removed once locking is updated such that blkg is never in limbo state between blkcg and request_queue locks. blk-throtl no longer shoots down root_tg to avoid breaking td->root_tg. Also, Nest queue_lock inside blkio_list_lock not the other way around to avoid introduce possible deadlock via blkcg lock. -v3: blkcg_clear_queue() repositioned and renamed to blkg_destroy_all() to increase consistency with later changes. cfq_clear_queue() updated to check q->elevator before dereferencing it to avoid NULL dereference on not fully initialized queues (used by later change). Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06block: implement blk_queue_bypass_start/end()Tejun Heo1-22/+3
Rename and extend elv_queisce_start/end() to blk_queue_bypass_start/end() which are exported and supports nesting via @q->bypass_depth. Also add blk_queue_bypass() to test bypass state. This will be further extended and used for blkio_group management. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06elevator: make elevator_init_fn() return 0/-errnoTejun Heo1-10/+2
elevator_ops->elevator_init_fn() has a weird return value. It returns a void * which the caller should assign to q->elevator->elevator_data and %NULL return denotes init failure. Update such that it returns integer 0/-errno and sets elevator_data directly as necessary. This makes the interface more conventional and eases further cleanup. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2012-03-06elevator: clear auxiliary data earlier during elevator switchTejun Heo1-45/+45
Elevator switch tries hard to keep as much as context until new elevator is ready so that it can revert to the original state if initializing the new elevator fails for some reason. Unfortunately, with more auxiliary contexts to manage, this makes elevator init and exit paths too complex and fragile. This patch makes elevator_switch() unregister the current elevator and flush icq's before start initializing the new one. As we still keep the old elevator itself, the only difference is that we lose icq's on rare occassions of switching failure, which isn't critical at all. Note that this makes explicit elevator parameter to elevator_init_queue() and __elv_register_queue() unnecessary as they always can use the current elevator. This patch enables block cgroup cleanups. -v2: blk_add_trace_msg() prints elevator name from @new_e instead of @e->type as the local variable no longer exists. This caused build failure on CONFIG_BLK_DEV_IO_TRACE. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-13 10:53:04 +0000