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* block: make ioc get/put interface more conventional and fix race on alloctionfaux1232016-01-084-54/+82
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Ignoring copy_io() during fork, io_context can be allocated from two places - current_io_context() and set_task_ioprio(). The former is always called from local task while the latter can be called from different task. The synchornization between them are peculiar and dubious. * current_io_context() doesn't grab task_lock() and assumes that if it saw %NULL ->io_context, it would stay that way until allocation and assignment is complete. It has smp_wmb() between alloc/init and assignment. * set_task_ioprio() grabs task_lock() for assignment and does smp_read_barrier_depends() between "ioc = task->io_context" and "if (ioc)". Unfortunately, this doesn't achieve anything - the latter is not a dependent load of the former. ie, if ioc itself were being dereferenced "ioc->xxx", it would mean something (not sure what tho) but as the code currently stands, the dependent read barrier is noop. As only one of the the two test-assignment sequences is task_lock() protected, the task_lock() can't do much about race between the two. Nothing prevents current_io_context() and set_task_ioprio() allocating its own ioc for the same task and overwriting the other's. Also, set_task_ioprio() can race with exiting task and create a new ioc after exit_io_context() is finished. ioc get/put doesn't have any reason to be complex. The only hot path is accessing the existing ioc of %current, which is simple to achieve given that ->io_context is never destroyed as long as the task is alive. All other paths can happily go through task_lock() like all other task sub structures without impacting anything. This patch updates ioc get/put so that it becomes more conventional. * alloc_io_context() is replaced with get_task_io_context(). This is the only interface which can acquire access to ioc of another task. On return, the caller has an explicit reference to the object which should be put using put_io_context() afterwards. * The functionality of current_io_context() remains the same but when creating a new ioc, it shares the code path with get_task_io_context() and always goes through task_lock(). * get_io_context() now means incrementing ref on an ioc which the caller already has access to (be that an explicit refcnt or implicit %current one). * PF_EXITING inhibits creation of new io_context and once exit_io_context() is finished, it's guaranteed that both ioc acquisition functions return %NULL. * All users are updated. Most are trivial but smp_read_barrier_depends() removal from cfq_get_io_context() needs a bit of explanation. I suppose the original intention was to ensure ioc->ioprio is visible when set_task_ioprio() allocates new io_context and installs it; however, this wouldn't have worked because set_task_ioprio() doesn't have wmb between init and install. There are other problems with this which will be fixed in another patch. * While at it, use NUMA_NO_NODE instead of -1 for wildcard node specification. -v2: Vivek spotted contamination from debug patch. Removed. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> modified by faux123
* block: rename the return of two functionsPaul Bolle2016-01-081-20/+20
| | | | | | | | | If we rename the return of alloc_io_context() and get_io_context() from "ret" to "ioc" the code get's (a bit) more readable and (a lot) more grepable. Signed-off-by: Paul Bolle <pebolle@tiscali.nl> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* block: misc ioc cleanupsfaux1232016-01-081-14/+16
| | | | | | | | | | | | | | | | | | | * int return from put_io_context() wasn't used by anybody. Make it return void like other put functions and docbook-fy the function comment. * Reorder dummy declarations for !CONFIG_BLOCK case a bit. * Make alloc_ioc_context() use __GFP_ZERO allocation, take init out of if block and drop 0'ing. * Docbook-fy current_io_context() comment. This patch doesn't introduce any functional change. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk> modified by faux123
* block, cfq: move cfqd->cic_index to q->idfaux1232016-01-084-55/+26
| | | | | | | | | | | | | cfq allocates per-queue id using ida and uses it to index cic radix tree from io_context. Move it to q->id and allocate on queue init and free on queue release. This simplifies cfq a bit and will allow for further improvements of io context life-cycle management. This patch doesn't introduce any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk> modified by faux123
* block: add missing blk_queue_dead() checksTejun Heo2016-01-082-2/+25
| | | | | | | | | | | | | blk_insert_cloned_request(), blk_execute_rq_nowait() and blk_flush_plug_list() either didn't check whether the queue was dead or did it without holding queue_lock. Update them so that dead state is checked while holding queue_lock. AFAICS, this plugs all holes (requeue doesn't matter as the request is transitioning atomically from in_flight to queued). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: fix drain_all condition in blk_drain_queue()Tejun Heo2016-01-081-6/+18
| | | | | | | | | | When trying to drain all requests, blk_drain_queue() checked only q->rq.count[]; however, this only tracks REQ_ALLOCED requests. This patch updates blk_drain_queue() such that it looks at all the counters and queues so that request_queue is actually empty on completion. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: add blk_queue_dead()Tejun Heo2016-01-085-9/+9
| | | | | | | | | | There are a number of QUEUE_FLAG_DEAD tests. Add blk_queue_dead() macro and use it. This patch doesn't introduce any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: add missed trace_block_plugShaohua Li2016-01-081-1/+3
| | | | | | | | | | After flush plug list, the list has no request, so we need to add a trace_block_plug(). Signed-off-by: Shaohua Li <shaohua.li@intel.com> Reviewed-by: Namhyung Kim <namhyung@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: avoid unnecessary plug list flushShaohua Li2016-01-081-2/+0
| | | | | | | | | | get_request_wait() could sleep and flush the plug list. If the list is already flushed, don't flush again. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Reviewed-by: Namhyung Kim <namhyung@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: don't call blk_drain_queue() if elevator is not upTejun Heo2016-01-081-2/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | blk_cleanup_queue() may be called before elevator is set up on a queue which triggers the following oops. BUG: unable to handle kernel NULL pointer dereference at (null) IP: [<ffffffff8125a69c>] elv_drain_elevator+0x1c/0x70 ... Pid: 830, comm: kworker/0:2 Not tainted 3.1.0-next-20111025_64+ #1590 Bochs Bochs RIP: 0010:[<ffffffff8125a69c>] [<ffffffff8125a69c>] elv_drain_elevator+0x1c/0x70 ... Call Trace: [<ffffffff8125da92>] blk_drain_queue+0x42/0x70 [<ffffffff8125db90>] blk_cleanup_queue+0xd0/0x1c0 [<ffffffff81469640>] md_free+0x50/0x70 [<ffffffff8126f43b>] kobject_release+0x8b/0x1d0 [<ffffffff81270d56>] kref_put+0x36/0xa0 [<ffffffff8126f2b7>] kobject_put+0x27/0x60 [<ffffffff814693af>] mddev_delayed_delete+0x2f/0x40 [<ffffffff81083450>] process_one_work+0x100/0x3b0 [<ffffffff8108527f>] worker_thread+0x15f/0x3a0 [<ffffffff81089937>] kthread+0x87/0x90 [<ffffffff81621834>] kernel_thread_helper+0x4/0x10 Fix it by making blk_cleanup_queue() check whether q->elevator is set up before invoking blk_drain_queue. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blk-throttle: use queue_is_locked() instead of lockdep_is_held()Jens Axboe2016-01-081-1/+1
| | | | | | | We can't use the latter if !CONFIG_LOCKDEP. Reported-by: Sedat Dilek <sedat.dilek@googlemail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blk-throttle: Take blkcg->lock while traversing blkcg->policy_listVivek Goyal2016-01-081-14/+40
| | | | | | | | | | blkcg->policy_list is protected by blkcg->lock. Its not rcu protected list. So even for readers, they need to take blkcg->lock. There are few functions which were reading the list without taking lock. Fix it. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blk-throttle: Free up policy node associated with deleted ruleVivek Goyal2016-01-081-0/+1
| | | | | | | | | If a rule is being deleted, free up associated policy node. Otherwise that memory is leaked. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: warn if tag is greater than real_max_depth.Tao Ma2016-01-081-2/+4
| | | | | | | | | In case tag depth is reduced, it is max_depth not real_max_depth. So we should allow a request with tag >= max_depth, but for a tag >= real_max_depth, there really should be some problem. Signed-off-by: Tao Ma <boyu.mt@taobao.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blk-flush: move the queue kick intoJeff Moyer2016-01-082-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | A dm-multipath user reported[1] a problem when trying to boot a kernel with commit 4853abaae7e4a2af938115ce9071ef8684fb7af4 (block: fix flush machinery for stacking drivers with differring flush flags) applied. It turns out that an empty flush request can be sent into blk_insert_flush. When the BUG_ON was fixed to allow for this, I/O on the underlying device would stall. The reason is that blk_insert_cloned_request does not kick the queue. In the aforementioned commit, I had added a special case to kick the queue if data was sent down but the queue flags did not require a flush. A better solution is to push the queue kick up into blk_insert_cloned_request. This patch, along with a follow-on which fixes the BUG_ON, fixes the issue reported. [1] http://www.redhat.com/archives/dm-devel/2011-September/msg00154.html Reported-by: Christophe Saout <christophe@saout.de> Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> Stable note: 3.1 Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blk-flush: fix invalid BUG_ON in blk_insert_flushJeff Moyer2016-01-081-1/+1
| | | | | | | | | | | | | | | | | | | | A user reported a regression due to commit 4853abaae7e4a2af938115ce9071ef8684fb7af4 (block: fix flush machinery for stacking drivers with differring flush flags). Part of the problem is that blk_insert_flush required a single bio be attached to the request. In reality, having no attached bio is also a valid case, as can be observed with an empty flush. [1] http://www.redhat.com/archives/dm-devel/2011-September/msg00154.html Reported-by: Christophe Saout <christophe@saout.de> Signed-off-by: Jeff Moyer <jmoyer@redhat.com Acked-by: Tejun Heo <tj@kernel.org> Stable note: 3.1 Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: fix flush machinery for stacking drivers with differring flush flagsJeff Moyer2016-01-083-6/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit ae1b1539622fb46e51b4d13b3f9e5f4c713f86ae, block: reimplement FLUSH/FUA to support merge, introduced a performance regression when running any sort of fsyncing workload using dm-multipath and certain storage (in our case, an HP EVA). The test I ran was fs_mark, and it dropped from ~800 files/sec on ext4 to ~100 files/sec. It turns out that dm-multipath always advertised flush+fua support, and passed commands on down the stack, where those flags used to get stripped off. The above commit changed that behavior: static inline struct request *__elv_next_request(struct request_queue *q) { struct request *rq; while (1) { - while (!list_empty(&q->queue_head)) { + if (!list_empty(&q->queue_head)) { rq = list_entry_rq(q->queue_head.next); - if (!(rq->cmd_flags & (REQ_FLUSH | REQ_FUA)) || - (rq->cmd_flags & REQ_FLUSH_SEQ)) - return rq; - rq = blk_do_flush(q, rq); - if (rq) - return rq; + return rq; } Note that previously, a command would come in here, have REQ_FLUSH|REQ_FUA set, and then get handed off to blk_do_flush: struct request *blk_do_flush(struct request_queue *q, struct request *rq) { unsigned int fflags = q->flush_flags; /* may change, cache it */ bool has_flush = fflags & REQ_FLUSH, has_fua = fflags & REQ_FUA; bool do_preflush = has_flush && (rq->cmd_flags & REQ_FLUSH); bool do_postflush = has_flush && !has_fua && (rq->cmd_flags & REQ_FUA); unsigned skip = 0; ... if (blk_rq_sectors(rq) && !do_preflush && !do_postflush) { rq->cmd_flags &= ~REQ_FLUSH; if (!has_fua) rq->cmd_flags &= ~REQ_FUA; return rq; } So, the flush machinery was bypassed in such cases (q->flush_flags == 0 && rq->cmd_flags & (REQ_FLUSH|REQ_FUA)). Now, however, we don't get into the flush machinery at all. Instead, __elv_next_request just hands a request with flush and fua bits set to the scsi_request_fn, even if the underlying request_queue does not support flush or fua. The agreed upon approach is to fix the flush machinery to allow stacking. While this isn't used in practice (since there is only one request-based dm target, and that target will now reflect the flush flags of the underlying device), it does future-proof the solution, and make it function as designed. In order to make this work, I had to add a field to the struct request, inside the flush structure (to store the original req->end_io). Shaohua had suggested overloading the union with rb_node and completion_data, but the completion data is used by device mapper and can also be used by other drivers. So, I didn't see a way around the additional field. I tested this patch on an HP EVA with both ext4 and xfs, and it recovers the lost performance. Comments and other testers, as always, are appreciated. Cheers, Jeff Signed-off-by: Jeff Moyer <jmoyer@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* block: Remove the control of complete cpu from bio.Tao Ma2016-01-081-3/+1
| | | | | | | | | | | | | | | | | | | | | bio originally has the functionality to set the complete cpu, but it is broken. Chirstoph said that "This code is unused, and from the all the discussions lately pretty obviously broken. The only thing keeping it serves is creating more confusion and possibly more bugs." And Jens replied with "We can kill bio_set_completion_cpu(). I'm fine with leaving cpu control to the request based drivers, they are the only ones that can toggle the setting anyway". So this patch tries to remove all the work of controling complete cpu from a bio. Cc: Shaohua Li <shaohua.li@intel.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Tao Ma <boyu.mt@taobao.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: fix a typo in the blk-cgroup.h fileJie Liu2016-01-081-1/+1
| | | | | | | byptes -> bytes. Signed-off-by: Jie Liu <jeff.liu@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: fix request_queue lifetime handling by making blk_queue_cleanup() ↵Tejun Heo2016-01-085-29/+87
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | properly shutdown request_queue is refcounted but actually depdends on lifetime management from the queue owner - on blk_cleanup_queue(), block layer expects that there's no request passing through request_queue and no new one will. This is fundamentally broken. The queue owner (e.g. SCSI layer) doesn't have a way to know whether there are other active users before calling blk_cleanup_queue() and other users (e.g. bsg) don't have any guarantee that the queue is and would stay valid while it's holding a reference. With delay added in blk_queue_bio() before queue_lock is grabbed, the following oops can be easily triggered when a device is removed with in-flight IOs. sd 0:0:1:0: [sdb] Stopping disk ata1.01: disabled general protection fault: 0000 [#1] PREEMPT SMP CPU 2 Modules linked in: Pid: 648, comm: test_rawio Not tainted 3.1.0-rc3-work+ #56 Bochs Bochs RIP: 0010:[<ffffffff8137d651>] [<ffffffff8137d651>] elv_rqhash_find+0x61/0x100 ... Process test_rawio (pid: 648, threadinfo ffff880019efa000, task ffff880019ef8a80) ... Call Trace: [<ffffffff8137d774>] elv_merge+0x84/0xe0 [<ffffffff81385b54>] blk_queue_bio+0xf4/0x400 [<ffffffff813838ea>] generic_make_request+0xca/0x100 [<ffffffff81383994>] submit_bio+0x74/0x100 [<ffffffff811c53ec>] dio_bio_submit+0xbc/0xc0 [<ffffffff811c610e>] __blockdev_direct_IO+0x92e/0xb40 [<ffffffff811c39f7>] blkdev_direct_IO+0x57/0x60 [<ffffffff8113b1c5>] generic_file_aio_read+0x6d5/0x760 [<ffffffff8118c1ca>] do_sync_read+0xda/0x120 [<ffffffff8118ce55>] vfs_read+0xc5/0x180 [<ffffffff8118cfaa>] sys_pread64+0x9a/0xb0 [<ffffffff81afaf6b>] system_call_fastpath+0x16/0x1b This happens because blk_queue_cleanup() destroys the queue and elevator whether IOs are in progress or not and DEAD tests are sprinkled in the request processing path without proper synchronization. Similar problem exists for blk-throtl. On queue cleanup, blk-throtl is shutdown whether it has requests in it or not. Depending on timing, it either oopses or throttled bios are lost putting tasks which are waiting for bio completion into eternal D state. The way it should work is having the usual clear distinction between shutdown and release. Shutdown drains all currently pending requests, marks the queue dead, and performs partial teardown of the now unnecessary part of the queue. Even after shutdown is complete, reference holders are still allowed to issue requests to the queue although they will be immmediately failed. The rest of teardown happens on release. This patch makes the following changes to make blk_queue_cleanup() behave as proper shutdown. * QUEUE_FLAG_DEAD is now set while holding both q->exit_mutex and queue_lock. * Unsynchronized DEAD check in generic_make_request_checks() removed. This couldn't make any meaningful difference as the queue could die after the check. * blk_drain_queue() updated such that it can drain all requests and is now called during cleanup. * blk_throtl updated such that it checks DEAD on grabbing queue_lock, drains all throttled bios during cleanup and free td when queue is released. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: drop @tsk from attempt_plug_merge() and explain sync rulesTejun Heo2016-01-081-7/+21
| | | | | | | | | | | | | | | | attempt_plug_merge() accesses elevator without holding queue_lock and may call into ->elevator_bio_merge_fn(). The elvator is guaranteed to be valid because it's accessed iff the plugged list has requests and elevator is never exited with live requests, so as long as the elevator method can deal with unlocked access, this is safe. Explain the sync rules around attempt_plug_merge() and drop the unnecessary @tsk parameter. This patch doesn't introduce any functional change. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: make get_request[_wait]() fail if queue is deadTejun Heo2016-01-081-16/+38
| | | | | | | | | | | | | | | | | Currently get_request[_wait]() allocates request whether queue is dead or not. This patch makes get_request[_wait]() return NULL if @q is dead. blk_queue_bio() is updated to fail the submitted bio if request allocation fails. While at it, add docbook comments for get_request[_wait](). Note that the current code has rather unclear (there are spurious DEAD tests scattered around) assumption that the owner of a queue guarantees that no request travels block layer if the queue is dead and this patch in itself doesn't change much; however, this will allow fixing the broken assumption in the next patch. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: reorganize throtl_get_tg() and blk_throtl_bio()Tejun Heo2016-01-083-41/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | blk_throtl_bio() and throtl_get_tg() have rather unusual interface. * throtl_get_tg() returns pointer to a valid tg or ERR_PTR(-ENODEV), and drops queue_lock in the latter case. Different locking context depending on return value is error-prone and DEAD state is scheduled to be protected by queue_lock anyway. Move DEAD check inside queue_lock and return valid tg or NULL. * blk_throtl_bio() indicates return status both with its return value and in/out param **@bio. The former is used to indicate whether queue is found to be dead during throtl processing. The latter whether the bio is throttled. There's no point in returning DEAD check result from blk_throtl_bio(). The queue can die after blk_throtl_bio() is finished but before make_request_fn() grabs queue lock. Make it take *@bio instead and return boolean result indicating whether the request is throttled or not. This patch doesn't cause any visible functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: reorganize queue drainingTejun Heo2016-01-083-26/+40
| | | | | | | | | | | | | | | | | | Reorganize queue draining related code in preparation of queue exit changes. * Factor out actual draining from elv_quiesce_start() to blk_drain_queue(). * Make elv_quiesce_start/end() responsible for their own locking. * Replace open-coded ELVSWITCH clearing in elevator_switch() with elv_quiesce_end(). This patch doesn't cause any visible functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: drop unnecessary blk_get/put_queue() in scsi_cmd_ioctl() and blk_get_tg()Tejun Heo2016-01-082-9/+2
| | | | | | | | | | | | | | | | | | | | | | blk_get/put_queue() in scsi_cmd_ioctl() and throtl_get_tg() are completely bogus. The caller must have a reference to the queue on entry and taking an extra reference doesn't change anything. For scsi_cmd_ioctl(), the only effect is that it ends up checking QUEUE_FLAG_DEAD on entry; however, this is bogus as queue can die right after blk_get_queue(). Dead queue should be and is handled in request issue path (it's somewhat broken now but that's a separate problem and doesn't affect this one much). throtl_get_tg() incorrectly assumes that q is rcu freed. Also, it doesn't check return value of blk_get_queue(). If the queue is already dead, it ends up doing an extra put. Drop them. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: pass around REQ_* flags instead of broken down booleans during ↵Tejun Heo2016-01-081-19/+17
| | | | | | | | | | | | | | request alloc/free blk_alloc_request() and freed_request() take different combinations of REQ_* @flags, @priv and @is_sync when @flags is superset of the latter two. Make them take @flags only. This cleans up the code a bit and will ease updating allocation related REQ_* flags. This patch doesn't introduce any functional difference. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: move blk_throtl prototypes to block/blk.hTejun Heo2016-01-082-1/+15
| | | | | | | | | | | blk_throtl interface is block internal and there's no reason to have them in linux/blkdev.h. Move them to block/blk.h. This patch doesn't introduce any functional change. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: fix genhd refcounting in blkio_policy_parse_and_set()Tejun Heo2016-01-081-33/+23
| | | | | | | | | | | | | blkio_policy_parse_and_set() calls blkio_check_dev_num() to check whether the given dev_t is valid. blkio_check_dev_num() uses get_gendisk() for verification but never puts the returned genhd leaking the reference. This patch collapses blkio_check_dev_num() into its caller and updates it such that the genhd is put before returning. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block/blk-sysfs.c: fix kerneldoc referencesAndrew Morton2016-01-081-3/+3
| | | | | | | | The kerneldoc for blk_release_queue() is referring to blk_cleanup_queue(). Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@google.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: document blk-plugfaux1232016-01-081-0/+14
| | | | | | | | | | | | | | | | | | | | | | | | Thus spake Andrew Morton: "And I have the usual maintainability whine. If someone comes up to vmscan.c and sees it calling blk_start_plug(), how are they supposed to work out why that call is there? They go look at the blk_start_plug() definition and it is undocumented. I think we can do better than this?" Adapted from the LWN article - http://lwn.net/Articles/438256/ by Jens Axboe and from an earlier attempt by Shaohua Li to document blk-plug. [akpm@linux-foundation.org: grammatical and spelling tweaks] Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de> Cc: Shaohua Li <shaohua.li@intel.com> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@google.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Conflicts: include/linux/blkdev.h modified by faux123
* block: refactor generic_make_requestChristoph Hellwig2016-01-081-46/+49
| | | | | | | | | | | | | Move all the checks performed on a bio into a new helper, and call it as soon as bio is submitted even if it is a re-submission from ->make_request. We explicitly mark the new helper as beeing non-inlined as the stack usage for printing the block device name in the failure case is quite high and this a patch where we have to be extremely conservative about stack usage. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: Don't check QUEUE_FLAG_SAME_COMP in __blk_complete_requestTao Ma2016-01-081-1/+1
| | | | | | | | | | | In __blk_complete_request, we check both QUEUE_FLAG_SAME_COMP and req->cpu to decide whether we should use req->cpu. Actually the user can also select the complete cpu by either setting BIO_CPU_AFFINE or by calling bio_set_completion_cpu. Current solution makes these 2 ways don't work any more. So we'd better just check req->cpu. Signed-off-by: Tao Ma <boyu.mt@taobao.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: remove support for bio remapping from ->make_requestfaux1232016-01-081-91/+62
| | | | | | | | | | | | | | | | | | | | | | | | | | | | There is very little benefit in allowing to let a ->make_request instance update the bios device and sector and loop around it in __generic_make_request when we can archive the same through calling generic_make_request from the driver and letting the loop in generic_make_request handle it. Note that various drivers got the return value from ->make_request and returned non-zero values for errors. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: NeilBrown <neilb@suse.de> Signed-off-by: Jens Axboe <jaxboe@fusionio.com> Conflicts: block/blk-core.c drivers/md/raid1.c drivers/md/raid10.c drivers/staging/zram/zram_drv.c modified by faux123 Conflicts: drivers/block/umem.c Change-Id: I598876e1b7e31f13299512e58e01bb42c7db949d
* fail_make_request: cleanup should_fail_requestAkinobu Mita2016-01-081-14/+12
| | | | | | | | | | | This changes should_fail_request() to more usable wrapper function of should_fail(). It can avoid putting #ifdef CONFIG_FAIL_MAKE_REQUEST in the middle of a function. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* block: fix warning with calling smp_processor_id() in preemptible sectionJens Axboe2016-01-081-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | After commit 5757a6d7 introduced an unsafe calling of smp_processor_id(), with preempt debuggin turned on we spew a lot of: BUG: using smp_processor_id() in preemptible [00000000] code: kjournald/514 caller is __make_request+0x1b8/0x308 [<c0019f44>] (unwind_backtrace+0x0/0xe8) from [<c024b4cc>] (debug_smp_processor_id+0xbc/0xf0) [<c024b4cc>] (debug_smp_processor_id+0xbc/0xf0) from [<c0223d14>] (__make_request+0x1b8/0x308) [<c0223d14>] (__make_request+0x1b8/0x308) from [<c02215ac>] (generic_make_request+0x4dc/0x558) [<c02215ac>] (generic_make_request+0x4dc/0x558) from [<c022173c>] (submit_bio+0x114/0x138) [<c022173c>] (submit_bio+0x114/0x138) from [<c011f504>] (submit_bh+0x148/0x16c) [<c011f504>] (submit_bh+0x148/0x16c) from [<c0121ed8>] (__sync_dirty_buffer+0x88/0xd8) [<c0121ed8>] (__sync_dirty_buffer+0x88/0xd8) from [<c01aff78>] (journal_commit_transaction+0x1198/0x1688) [<c01aff78>] (journal_commit_transaction+0x1198/0x1688) from [<c01b4034>] (kjournald+0xb4/0x224) [<c01b4034>] (kjournald+0xb4/0x224) from [<c0069ea0>] (kthread+0x8c/0x94) [<c0069ea0>] (kthread+0x8c/0x94) from [<c00137f8>] (kernel_thread_exit+0x0/0x8) Fix this by just using raw_smp_processor_id(), it's just a hint after all. There's no pinning of the CPU or accessing per-cpu structures involved. Reported-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* block: rename __make_request() to blk_queue_bio()Jens Axboe2016-01-081-3/+3
| | | | | | Now that it's exported, lets put it in a more sane namespace. Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* block: export __make_requestChristoph Hellwig2016-01-081-3/+2
| | | | | | | | Avoid the hacks need for request based device mappers currently by simply exporting the symbol instead of trying to get it through the back door. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* elevator: use ELV_NAME_MAX instead of magic number 16 for chosen_elevatorWang Sheng-Hui2016-01-081-1/+1
| | | | | | | | We have ELV_NAME_MAX defined to 16, and hence we should use it instead of the magic nubmer 16 for elevator's name string. Signed-off-by: Wang Sheng-Hui <shhuiw@gmail.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* block: simplify force plug flush code a little bitShaohua Li2016-01-081-4/+1
| | | | | | | | | | | | | | Cleaning up the code a little bit. attempt_plug_merge() traverses the plug list anyway, we can do the request counting there, so stack size is reduced a little bit. The motivation here is I suspect if we should count the requests for each queue (task could handle multiple disks in the meantime), but my test doesn't show it's worthy doing. If somebody proves we should do it, below change will make that more easier. Signed-off-by: Shaohua Li <shli@kernel.org> Signed-off-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* block: change force plug flush call orderShaohua Li2016-01-081-3/+3
| | | | | | | | | | | | Do blk_flush_plug_list() first and then add new request aDo blk_flush_plug_list() first and then add new request aDo blk_flush_plug_list() first and then add new request at the tail. New request can't be merged to existing requests, but later new requests might be merged with this new one. If blk_flush_plug_list() is done later, the merge doesn't happen. Believe it or not, this fixes a 10% regression running sysbench workload. Signed-off-by: Shaohua Li <shli@kernel.org> Signed-off-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* block: Fix queue_flag update when rq_affinity goes from 2 to 1Eric Seppanen2016-01-081-4/+6
| | | | | | | | | | | Commit 5757a6d76cdf added the QUEUE_FLAG_SAME_FORCE flag, but fails to clear that flag when the current state is '2' (SAME_COMP + SAME_FORCE) and the new state is '1' (SAME_COMP). Acked-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Roland Dreier <roland@purestorage.com> Signed-off-by: Eric Seppanen <eric@purestorage.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* block: strict rq_affinityDan Williams2016-01-083-12/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | Some systems benefit from completions always being steered to the strict requester cpu rather than the looser "per-socket" steering that blk_cpu_to_group() attempts by default. This is because the first CPU in the group mask ends up being completely overloaded with work, while the others (including the original submitter) has power left to spare. Allow the strict mode to be set by writing '2' to the sysfs control file. This is identical to the scheme used for the nomerges file, where '2' is a more aggressive setting than just being turned on. echo 2 > /sys/block/<bdev>/queue/rq_affinity Cc: Christoph Hellwig <hch@infradead.org> Cc: Roland Dreier <roland@purestorage.com> Tested-by: Dave Jiang <dave.jiang@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com> Conflicts: include/linux/blkdev.h Change-Id: I9073251d611e61cdd6163975618c2a6d5bbbe45c
* cfq-iosched: Reduce linked group count upon group destructionVivek Goyal2016-01-081-0/+3
| | | | | | | | | | | | | | | | | | FQ keeps track of number of groups which are linked on blkcg->blkg_list. This is useful to avoid races between queue exit and cgroup exit code paths. So if at the request queue exit time linked group count is not zero, that means there are some group out there which is yet to be deleted under rcu read period and queue exit code should wait for on rcu period. In my previous patch I forgot to decrease the number of group count. So in current form, we nr_blkcg_linked_grps is always non-zero and we will always wait one rcu period (if BLK_CGROUP=y). The side effect of this is that it can increase boot time. I am surprised, nobody complained so far. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* CFQ: add think time check for groupShaohua Li2016-01-081-2/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently when the last queue of a group has no request, we don't expire the queue to hope request from the group comes soon, so the group doesn't miss its share. But if the think time is big, the assumption isn't correct and we just waste bandwidth. In such case, we don't do idle. [global] runtime=30 direct=1 [test1] cgroup=test1 cgroup_weight=1000 rw=randread ioengine=libaio size=500m runtime=30 directory=/mnt filename=file1 thinktime=9000 [test2] cgroup=test2 cgroup_weight=1000 rw=randread ioengine=libaio size=500m runtime=30 directory=/mnt filename=file2 patched base test1 64k 39k test2 548k 540k total 604k 578k group1 gets much better throughput because it waits less time. To check if the patch changes behavior of queue without think time. I also tried to give test1 2ms think time or no think time. The test result is stable. The thoughput doesn't change with/without the patch. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* CFQ: add think time check for service treeShaohua Li2016-01-081-4/+30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently when the last queue of a service tree has no request, we don't expire the queue to hope request from the service tree comes soon, so the service tree doesn't miss its share. But if the think time is big, the assumption isn't correct and we just waste bandwidth. In such case, we don't do idle. [global] runtime=10 direct=1 [test1] rw=randread ioengine=libaio size=500m directory=/mnt filename=file1 thinktime=9000 [test2] rw=read ioengine=libaio size=1G directory=/mnt filename=file2 patched base test1 41k/s 33k/s test2 15868k/s 15789k/s total 15902k/s 15817k/s A slightly better To check if the patch changes behavior of queue without think time. I also tried to give test1 2ms think time or no think time. The test has variation even without the patch, but the average throughput doesn't change with/without the patch. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* CFQ: move think time check variables to a separate structShaohua Li2016-01-081-16/+24
| | | | | | | | | | Move the variables to do think time check to a sepatate struct. This is to prepare adding think time check for service tree and group. No functional change. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* fixlet: Remove fs_excl from struct task.Justin TerAvest2016-01-081-27/+1
| | | | | | | | | | | | | | | | | fs_excl is a poor man's priority inheritance for filesystems to hint to the block layer that an operation is important. It was never clearly specified, not widely adopted, and will not prevent starvation in many cases (like across cgroups). fs_excl was introduced with the time sliced CFQ IO scheduler, to indicate when a process held FS exclusive resources and thus needed a boost. It doesn't cover all file systems, and it was never fully complete. Lets kill it. Signed-off-by: Justin TerAvest <teravest@google.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
* block: avoid unnecessary plug list flushShaohua Li2016-01-081-7/+9
| | | | | | | | | | get_request_wait() could sleep and flush the plug list. If the list is already flushed, don't flush again. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Reviewed-by: Namhyung Kim <namhyung@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block, sx8: kill blk_insert_request()Tejun Heo2016-01-081-48/+0
| | | | | | | | | | | | | | | The only user left for blk_insert_request() is sx8 and it can be trivially switched to use blk_execute_rq_nowait() - special requests aren't included in io stat and sx8 doesn't use block layer tagging. Switch sx8 and kill blk_insert_requeset(). This patch doesn't introduce any functional difference. Only compile tested. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Jeff Garzik <jgarzik@pobox.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* block: simplify force plug flush code a little bitShaohua Li2016-01-081-2/+8
| | | | | | | | | | | | | | | Cleaning up the code a little bit. attempt_plug_merge() traverses the plug list anyway, we can do the request counting there, so stack size is reduced a little bit. The motivation here is I suspect if we should count the requests for each queue (task could handle multiple disks in the meantime), but my test doesn't show it's worthy doing. If somebody proves we should do it, below change will make that more easier. Signed-off-by: Shaohua Li <shli@kernel.org> Signed-off-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com> merged conflict resolved by faux123
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