- 01 9月, 2015 1 次提交
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由 Qu Wenruo 提交于
At initializing time, for threshold-able workqueue, it's max_active of kernel workqueue should be 1 and grow if it hits threshold. But due to the bad naming, there is both 'max_active' for kernel workqueue and btrfs workqueue. So wrong value is given at workqueue initialization. This patch fixes it, and to avoid further misunderstanding, change the member name of btrfs_workqueue to 'current_active' and 'limit_active'. Also corresponding comment is added for readability. Reported-by: NAlex Lyakas <alex.btrfs@zadarastorage.com> Signed-off-by: NQu Wenruo <quwenruo@cn.fujitsu.com> Signed-off-by: NChris Mason <clm@fb.com>
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- 10 6月, 2015 1 次提交
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由 Zhao Lei 提交于
lockdep report following warning in test: [25176.843958] ================================= [25176.844519] [ INFO: inconsistent lock state ] [25176.845047] 4.1.0-rc3 #22 Tainted: G W [25176.845591] --------------------------------- [25176.846153] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. [25176.846713] fsstress/26661 [HC0[0]:SC1[1]:HE1:SE0] takes: [25176.847246] (&wr_ctx->wr_lock){+.?...}, at: [<ffffffffa04cdc6d>] scrub_free_ctx+0x2d/0xf0 [btrfs] [25176.847838] {SOFTIRQ-ON-W} state was registered at: [25176.848396] [<ffffffff810bf460>] __lock_acquire+0x6a0/0xe10 [25176.848955] [<ffffffff810bfd1e>] lock_acquire+0xce/0x2c0 [25176.849491] [<ffffffff816489af>] mutex_lock_nested+0x7f/0x410 [25176.850029] [<ffffffffa04d04ff>] scrub_stripe+0x4df/0x1080 [btrfs] [25176.850575] [<ffffffffa04d11b1>] scrub_chunk.isra.19+0x111/0x130 [btrfs] [25176.851110] [<ffffffffa04d144c>] scrub_enumerate_chunks+0x27c/0x510 [btrfs] [25176.851660] [<ffffffffa04d3b87>] btrfs_scrub_dev+0x1c7/0x6c0 [btrfs] [25176.852189] [<ffffffffa04e918e>] btrfs_dev_replace_start+0x36e/0x450 [btrfs] [25176.852771] [<ffffffffa04a98e0>] btrfs_ioctl+0x1e10/0x2d20 [btrfs] [25176.853315] [<ffffffff8121c5b8>] do_vfs_ioctl+0x318/0x570 [25176.853868] [<ffffffff8121c851>] SyS_ioctl+0x41/0x80 [25176.854406] [<ffffffff8164da17>] system_call_fastpath+0x12/0x6f [25176.854935] irq event stamp: 51506 [25176.855511] hardirqs last enabled at (51506): [<ffffffff810d4ce5>] vprintk_emit+0x225/0x5e0 [25176.856059] hardirqs last disabled at (51505): [<ffffffff810d4b77>] vprintk_emit+0xb7/0x5e0 [25176.856642] softirqs last enabled at (50886): [<ffffffff81067a23>] __do_softirq+0x363/0x640 [25176.857184] softirqs last disabled at (50949): [<ffffffff8106804d>] irq_exit+0x10d/0x120 [25176.857746] other info that might help us debug this: [25176.858845] Possible unsafe locking scenario: [25176.859981] CPU0 [25176.860537] ---- [25176.861059] lock(&wr_ctx->wr_lock); [25176.861705] <Interrupt> [25176.862272] lock(&wr_ctx->wr_lock); [25176.862881] *** DEADLOCK *** Reason: Above warning is caused by: Interrupt -> bio_endio() -> ... -> scrub_put_ctx() -> scrub_free_ctx() *1 -> ... -> mutex_lock(&wr_ctx->wr_lock); scrub_put_ctx() is allowed to be called in end_bio interrupt, but in code design, it will never call scrub_free_ctx(sctx) in interrupe context(above *1), because btrfs_scrub_dev() get one additional reference of sctx->refs, which makes scrub_free_ctx() only called withine btrfs_scrub_dev(). Now the code runs out of our wish, because free sequence in scrub_pending_bio_dec() have a gap. Current code: -----------------------------------+----------------------------------- scrub_pending_bio_dec() | btrfs_scrub_dev -----------------------------------+----------------------------------- atomic_dec(&sctx->bios_in_flight); | wake_up(&sctx->list_wait); | | scrub_put_ctx() | -> atomic_dec_and_test(&sctx->refs) scrub_put_ctx(sctx); | -> atomic_dec_and_test(&sctx->refs)| -> scrub_free_ctx() | -----------------------------------+----------------------------------- We expected: -----------------------------------+----------------------------------- scrub_pending_bio_dec() | btrfs_scrub_dev -----------------------------------+----------------------------------- atomic_dec(&sctx->bios_in_flight); | wake_up(&sctx->list_wait); | scrub_put_ctx(sctx); | -> atomic_dec_and_test(&sctx->refs)| | scrub_put_ctx() | -> atomic_dec_and_test(&sctx->refs) | -> scrub_free_ctx() -----------------------------------+----------------------------------- Fix: Move scrub_pending_bio_dec() to a workqueue, to avoid this function run in interrupt context. Tested by check tracelog in debug. Changelog v1->v2: Use workqueue instead of adjust function call sequence in v1, because v1 will introduce a bug pointed out by: Filipe David Manana <fdmanana@gmail.com> Reported-by: NQu Wenruo <quwenruo@cn.fujitsu.com> Signed-off-by: NZhao Lei <zhaolei@cn.fujitsu.com> Reviewed-by: NFilipe Manana <fdmanana@suse.com> Signed-off-by: NChris Mason <clm@fb.com>
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- 17 2月, 2015 1 次提交
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由 David Sterba 提交于
Through all the local wrappers to alloc_workqueue, __alloc_workqueue_key takes an unsigned int. Signed-off-by: NDavid Sterba <dsterba@suse.cz>
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- 18 9月, 2014 1 次提交
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由 Miao Xie 提交于
This patch implement data repair function when direct read fails. The detail of the implementation is: - When we find the data is not right, we try to read the data from the other mirror. - When the io on the mirror ends, we will insert the endio work into the dedicated btrfs workqueue, not common read endio workqueue, because the original endio work is still blocked in the btrfs endio workqueue, if we insert the endio work of the io on the mirror into that workqueue, deadlock would happen. - After we get right data, we write it back to the corrupted mirror. - And if the data on the new mirror is still corrupted, we will try next mirror until we read right data or all the mirrors are traversed. - After the above work, we set the uptodate flag according to the result. Signed-off-by: NMiao Xie <miaox@cn.fujitsu.com> Signed-off-by: NChris Mason <clm@fb.com>
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- 24 8月, 2014 1 次提交
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由 Liu Bo 提交于
This has been reported and discussed for a long time, and this hang occurs in both 3.15 and 3.16. Btrfs now migrates to use kernel workqueue, but it introduces this hang problem. Btrfs has a kind of work queued as an ordered way, which means that its ordered_func() must be processed in the way of FIFO, so it usually looks like -- normal_work_helper(arg) work = container_of(arg, struct btrfs_work, normal_work); work->func() <---- (we name it work X) for ordered_work in wq->ordered_list ordered_work->ordered_func() ordered_work->ordered_free() The hang is a rare case, first when we find free space, we get an uncached block group, then we go to read its free space cache inode for free space information, so it will file a readahead request btrfs_readpages() for page that is not in page cache __do_readpage() submit_extent_page() btrfs_submit_bio_hook() btrfs_bio_wq_end_io() submit_bio() end_workqueue_bio() <--(ret by the 1st endio) queue a work(named work Y) for the 2nd also the real endio() So the hang occurs when work Y's work_struct and work X's work_struct happens to share the same address. A bit more explanation, A,B,C -- struct btrfs_work arg -- struct work_struct kthread: worker_thread() pick up a work_struct from @worklist process_one_work(arg) worker->current_work = arg; <-- arg is A->normal_work worker->current_func(arg) normal_work_helper(arg) A = container_of(arg, struct btrfs_work, normal_work); A->func() A->ordered_func() A->ordered_free() <-- A gets freed B->ordered_func() submit_compressed_extents() find_free_extent() load_free_space_inode() ... <-- (the above readhead stack) end_workqueue_bio() btrfs_queue_work(work C) B->ordered_free() As if work A has a high priority in wq->ordered_list and there are more ordered works queued after it, such as B->ordered_func(), its memory could have been freed before normal_work_helper() returns, which means that kernel workqueue code worker_thread() still has worker->current_work pointer to be work A->normal_work's, ie. arg's address. Meanwhile, work C is allocated after work A is freed, work C->normal_work and work A->normal_work are likely to share the same address(I confirmed this with ftrace output, so I'm not just guessing, it's rare though). When another kthread picks up work C->normal_work to process, and finds our kthread is processing it(see find_worker_executing_work()), it'll think work C as a collision and skip then, which ends up nobody processing work C. So the situation is that our kthread is waiting forever on work C. Besides, there're other cases that can lead to deadlock, but the real problem is that all btrfs workqueue shares one work->func, -- normal_work_helper, so this makes each workqueue to have its own helper function, but only a wraper pf normal_work_helper. With this patch, I no long hit the above hang. Signed-off-by: NLiu Bo <bo.li.liu@oracle.com> Signed-off-by: NChris Mason <clm@fb.com>
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- 21 3月, 2014 1 次提交
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由 Qu Wenruo 提交于
Since most of the btrfs_workqueue is printed as pointer address, for easier analysis, add trace for btrfs_workqueue alloc/destroy. So it is possible to determine the workqueue that a given work belongs to(by comparing the wq pointer address with alloc trace event). Signed-off-by: NQu Wenruo <quenruo@cn.fujitsu.com> Signed-off-by: NChris Mason <clm@fb.com>
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- 11 3月, 2014 6 次提交
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由 Qu Wenruo 提交于
The new btrfs_workqueue still use open-coded function defition, this patch will change them into btrfs_func_t type which is much the same as kernel workqueue. Signed-off-by: NQu Wenruo <quwenruo@cn.fujitsu.com> Signed-off-by: NJosef Bacik <jbacik@fb.com>
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由 Qu Wenruo 提交于
Since the "_struct" suffix is mainly used for distinguish the differnt btrfs_work between the original and the newly created one, there is no need using the suffix since all btrfs_workers are changed into btrfs_workqueue. Also this patch fixed some codes whose code style is changed due to the too long "_struct" suffix. Signed-off-by: NQu Wenruo <quwenruo@cn.fujitsu.com> Tested-by: NDavid Sterba <dsterba@suse.cz> Signed-off-by: NJosef Bacik <jbacik@fb.com>
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由 Qu Wenruo 提交于
Since all the btrfs_worker is replaced with the newly created btrfs_workqueue, the old codes can be easily remove. Signed-off-by: NQuwenruo <quwenruo@cn.fujitsu.com> Tested-by: NDavid Sterba <dsterba@suse.cz> Signed-off-by: NJosef Bacik <jbacik@fb.com>
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由 Qu Wenruo 提交于
The original btrfs_workers has thresholding functions to dynamically create or destroy kthreads. Though there is no such function in kernel workqueue because the worker is not created manually, we can still use the workqueue_set_max_active to simulated the behavior, mainly to achieve a better HDD performance by setting a high threshold on submit_workers. (Sadly, no resource can be saved) So in this patch, extra workqueue pending counters are introduced to dynamically change the max active of each btrfs_workqueue_struct, hoping to restore the behavior of the original thresholding function. Also, workqueue_set_max_active use a mutex to protect workqueue_struct, which is not meant to be called too frequently, so a new interval mechanism is applied, that will only call workqueue_set_max_active after a count of work is queued. Hoping to balance both the random and sequence performance on HDD. Signed-off-by: NQu Wenruo <quwenruo@cn.fujitsu.com> Tested-by: NDavid Sterba <dsterba@suse.cz> Signed-off-by: NJosef Bacik <jbacik@fb.com>
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由 Qu Wenruo 提交于
Add high priority function to btrfs_workqueue. This is implemented by embedding a btrfs_workqueue into a btrfs_workqueue and use some helper functions to differ the normal priority wq and high priority wq. So the high priority wq is completely independent from the normal workqueue. Signed-off-by: NQu Wenruo <quwenruo@cn.fujitsu.com> Tested-by: NDavid Sterba <dsterba@suse.cz> Signed-off-by: NJosef Bacik <jbacik@fb.com>
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由 Qu Wenruo 提交于
Use kernel workqueue to implement a new btrfs_workqueue_struct, which has the ordering execution feature like the btrfs_worker. The func is executed in a concurrency way, and the ordred_func/ordered_free is executed in the sequence them are queued after the corresponding func is done. The new btrfs_workqueue works much like the original one, one workqueue for normal work and a list for ordered work. When a work is queued, ordered work will be added to the list and helper function will be queued into the workqueue. The helper function will execute a normal work and then check and execute as many ordered work as possible in the sequence they were queued. At this patch, high priority work queue or thresholding is not added yet. The high priority feature and thresholding will be added in the following patches. Signed-off-by: NQu Wenruo <quwenruo@cn.fujitsu.com> Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com> Tested-by: NDavid Sterba <dsterba@suse.cz> Signed-off-by: NJosef Bacik <jbacik@fb.com>
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- 05 10月, 2013 1 次提交
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由 Ilya Dryomov 提交于
The current implementation of worker threads in Btrfs has races in worker stopping code, which cause all kinds of panics and lockups when running btrfs/011 xfstest in a loop. The problem is that btrfs_stop_workers is unsynchronized with respect to check_idle_worker, check_busy_worker and __btrfs_start_workers. E.g., check_idle_worker race flow: btrfs_stop_workers(): check_idle_worker(aworker): - grabs the lock - splices the idle list into the working list - removes the first worker from the working list - releases the lock to wait for its kthread's completion - grabs the lock - if aworker is on the working list, moves aworker from the working list to the idle list - releases the lock - grabs the lock - puts the worker - removes the second worker from the working list ...... btrfs_stop_workers returns, aworker is on the idle list FS is umounted, memory is freed ...... aworker is waken up, fireworks ensue With this applied, I wasn't able to trigger the problem in 48 hours, whereas previously I could reliably reproduce at least one of these races within an hour. Reported-by: NDavid Sterba <dsterba@suse.cz> Signed-off-by: NIlya Dryomov <idryomov@gmail.com> Signed-off-by: NJosef Bacik <jbacik@fusionio.com>
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- 22 3月, 2012 1 次提交
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由 Jeff Mahoney 提交于
Signed-off-by: NJeff Mahoney <jeffm@suse.com>
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- 16 12月, 2011 1 次提交
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由 Josef Bacik 提交于
Al pointed out we have some random problems with the way we account for num_workers_starting in the async thread stuff. First of all we need to make sure to decrement num_workers_starting if we fail to start the worker, so make __btrfs_start_workers do this. Also fix __btrfs_start_workers so that it doesn't call btrfs_stop_workers(), there is no point in stopping everybody if we failed to create a worker. Also check_pending_worker_creates needs to call __btrfs_start_work in it's work function since it already increments num_workers_starting. People only start one worker at a time, so get rid of the num_workers argument everywhere, and make btrfs_queue_worker a void since it will always succeed. Thanks, Signed-off-by: NJosef Bacik <josef@redhat.com>
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- 05 10月, 2009 1 次提交
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由 Chris Mason 提交于
The btrfs async worker threads are used for a wide variety of things, including processing bio end_io functions. This means that when the endio threads aren't running, the rest of the FS isn't able to do the final processing required to clear PageWriteback. The endio threads also try to exit as they become idle and start more as the work piles up. The problem is that starting more threads means kthreadd may need to allocate ram, and that allocation may wait until the global number of writeback pages on the system is below a certain limit. The result of that throttling is that end IO threads wait on kthreadd, who is waiting on IO to end, which will never happen. This commit fixes the deadlock by handing off thread startup to a dedicated thread. It also fixes a bug where the on-demand thread creation was creating far too many threads because it didn't take into account threads being started by other procs. Signed-off-by: NChris Mason <chris.mason@oracle.com>
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- 12 9月, 2009 2 次提交
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由 Chris Mason 提交于
The btrfs worker thread spinlock was being used both for the queueing of IO and for the processing of ordered events. The ordered events never happen from end_io handlers, and so they don't need to use the _irq version of spinlocks. This adds a dedicated lock to the ordered lists so they don't have to run with irqs off. Signed-off-by: NChris Mason <chris.mason@oracle.com>
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由 Chris Mason 提交于
The Btrfs worker threads don't currently die off after they have been idle for a while, leading to a lot of threads sitting around doing nothing for each mount. Also, they are unable to start atomically (from end_io hanlders). This commit reworks the worker threads so they can be started from end_io handlers (just setting a flag that asks for a thread to be added at a later date) and so they can exit if they have been idle for a long time. Signed-off-by: NChris Mason <chris.mason@oracle.com>
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- 21 4月, 2009 1 次提交
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由 Chris Mason 提交于
Btrfs is using WRITE_SYNC_PLUG to send down synchronous IOs with a higher priority. But, the checksumming helper threads prevent it from being fully effective. There are two problems. First, a big queue of pending checksumming will delay the synchronous IO behind other lower priority writes. Second, the checksumming uses an ordered async work queue. The ordering makes sure that IOs are sent to the block layer in the same order they are sent to the checksumming threads. Usually this gives us less seeky IO. But, when we start mixing IO priorities, the lower priority IO can delay the higher priority IO. This patch solves both problems by adding a high priority list to the async helper threads, and a new btrfs_set_work_high_prio(), which is used to make put a new async work item onto the higher priority list. The ordering is still done on high priority IO, but all of the high priority bios are ordered separately from the low priority bios. This ordering is purely an IO optimization, it is not involved in data or metadata integrity. Signed-off-by: NChris Mason <chris.mason@oracle.com>
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- 07 11月, 2008 1 次提交
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由 Chris Mason 提交于
Btrfs uses kernel threads to create async work queues for cpu intensive operations such as checksumming and decompression. These work well, but they make it difficult to keep IO order intact. A single writepages call from pdflush or fsync will turn into a number of bios, and each bio is checksummed in parallel. Once the checksum is computed, the bio is sent down to the disk, and since we don't control the order in which the parallel operations happen, they might go down to the disk in almost any order. The code deals with this somewhat by having deep work queues for a single kernel thread, making it very likely that a single thread will process all the bios for a single inode. This patch introduces an explicitly ordered work queue. As work structs are placed into the queue they are put onto the tail of a list. They have three callbacks: ->func (cpu intensive processing here) ->ordered_func (order sensitive processing here) ->ordered_free (free the work struct, all processing is done) The work struct has three callbacks. The func callback does the cpu intensive work, and when it completes the work struct is marked as done. Every time a work struct completes, the list is checked to see if the head is marked as done. If so the ordered_func callback is used to do the order sensitive processing and the ordered_free callback is used to do any cleanup. Then we loop back and check the head of the list again. This patch also changes the checksumming code to use the ordered workqueues. One a 4 drive array, it increases streaming writes from 280MB/s to 350MB/s. Signed-off-by: NChris Mason <chris.mason@oracle.com>
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- 30 9月, 2008 1 次提交
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由 Chris Mason 提交于
This improves the comments at the top of many functions. It didn't dive into the guts of functions because I was trying to avoid merging problems with the new allocator and back reference work. extent-tree.c and volumes.c were both skipped, and there is definitely more work todo in cleaning and commenting the code. Signed-off-by: NChris Mason <chris.mason@oracle.com>
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- 25 9月, 2008 3 次提交
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由 Chris Mason 提交于
Signed-off-by: NChris Mason <chris.mason@oracle.com>
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由 Chris Mason 提交于
This changes the worker thread pool to maintain a list of idle threads, avoiding a complex search for a good thread to wake up. Threads have two states: idle - we try to reuse the last thread used in hopes of improving the batching ratios busy - each time a new work item is added to a busy task, the task is rotated to the end of the line. Signed-off-by: NChris Mason <chris.mason@oracle.com>
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由 Chris Mason 提交于
Btrfs has been using workqueues to spread the checksumming load across other CPUs in the system. But, workqueues only schedule work on the same CPU that queued the work, giving them a limited benefit for systems with higher CPU counts. This code adds a generic facility to schedule work with pools of kthreads, and changes the bio submission code to queue bios up. The queueing is important to make sure large numbers of procs on the system don't turn streaming workloads into random workloads by sending IO down concurrently. The end result of all of this is much higher performance (and CPU usage) when doing checksumming on large machines. Two worker pools are created, one for writes and one for endio processing. The two could deadlock if we tried to service both from a single pool. Signed-off-by: NChris Mason <chris.mason@oracle.com>
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