* [PATCH v2 0/3] btrfs: scrub: fix scrub_lock
@ 2018-11-29 9:25 Anand Jain
2018-11-29 9:25 ` [PATCH v2 1/3] btrfs: scrub: maintain the unlock order in scrub thread Anand Jain
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Anand Jain @ 2018-11-29 9:25 UTC (permalink / raw)
To: linux-btrfs
Idea was to fix the circular locking dependency warning as in patch 2/3,
and in the process also fixes the other identified cleanups patches 1/3,3/3
and they aren't dependent on 2ttch /3.
Anand Jain (3):
btrfs: scrub: maintain the unlock order in scrub thread
btrfs: scrub: fix circular locking dependency warning
btrfs: add lockdep check for scrub_lock in scrub_workers_get
fs/btrfs/scrub.c | 22 +++++++++++-----------
3 files changed, 13 insertions(+), 13 deletions(-)
--
1.8.3.1
^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH v2 1/3] btrfs: scrub: maintain the unlock order in scrub thread 2018-11-29 9:25 [PATCH v2 0/3] btrfs: scrub: fix scrub_lock Anand Jain @ 2018-11-29 9:25 ` Anand Jain 2018-11-29 10:36 ` Filipe Manana 2018-11-29 9:25 ` [PATCH v2 2/3] btrfs: scrub: fix circular locking dependency warning Anand Jain 2018-11-29 9:25 ` [PATCH v2 3/3] btrfs: scrub: add scrub_lock lockdep check in scrub_workers_get Anand Jain 2 siblings, 1 reply; 6+ messages in thread From: Anand Jain @ 2018-11-29 9:25 UTC (permalink / raw) To: linux-btrfs The device_list_mutex and scrub_lock creates a nested locks in btrfs_scrub_dev(). During lock the order is device_list_mutex and then scrub_lock, and during unlock, the order is device_list_mutex and then scrub_lock. Fix this to the lock order of scrub_lock and then device_list_mutex. Signed-off-by: Anand Jain <anand.jain@oracle.com> --- v1->v2: change the order of lock acquire first scrub_lock and then device_list_mutex, which matches with the order of unlock. The extra line which are now in the scrub_lock are ok to be under the scrub_lock. fs/btrfs/scrub.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index 902819d3cf41..a9d6fc3b01d4 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -3813,28 +3813,29 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start, return -EINVAL; } - + mutex_lock(&fs_info->scrub_lock); mutex_lock(&fs_info->fs_devices->device_list_mutex); dev = btrfs_find_device(fs_info, devid, NULL, NULL); if (!dev || (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state) && !is_dev_replace)) { mutex_unlock(&fs_info->fs_devices->device_list_mutex); + mutex_unlock(&fs_info->scrub_lock); return -ENODEV; } if (!is_dev_replace && !readonly && !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state)) { mutex_unlock(&fs_info->fs_devices->device_list_mutex); + mutex_unlock(&fs_info->scrub_lock); btrfs_err_in_rcu(fs_info, "scrub: device %s is not writable", rcu_str_deref(dev->name)); return -EROFS; } - mutex_lock(&fs_info->scrub_lock); if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &dev->dev_state) || test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &dev->dev_state)) { - mutex_unlock(&fs_info->scrub_lock); mutex_unlock(&fs_info->fs_devices->device_list_mutex); + mutex_unlock(&fs_info->scrub_lock); return -EIO; } @@ -3843,23 +3844,23 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start, (!is_dev_replace && btrfs_dev_replace_is_ongoing(&fs_info->dev_replace))) { btrfs_dev_replace_read_unlock(&fs_info->dev_replace); - mutex_unlock(&fs_info->scrub_lock); mutex_unlock(&fs_info->fs_devices->device_list_mutex); + mutex_unlock(&fs_info->scrub_lock); return -EINPROGRESS; } btrfs_dev_replace_read_unlock(&fs_info->dev_replace); ret = scrub_workers_get(fs_info, is_dev_replace); if (ret) { - mutex_unlock(&fs_info->scrub_lock); mutex_unlock(&fs_info->fs_devices->device_list_mutex); + mutex_unlock(&fs_info->scrub_lock); return ret; } sctx = scrub_setup_ctx(dev, is_dev_replace); if (IS_ERR(sctx)) { - mutex_unlock(&fs_info->scrub_lock); mutex_unlock(&fs_info->fs_devices->device_list_mutex); + mutex_unlock(&fs_info->scrub_lock); scrub_workers_put(fs_info); return PTR_ERR(sctx); } -- 1.8.3.1 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v2 1/3] btrfs: scrub: maintain the unlock order in scrub thread 2018-11-29 9:25 ` [PATCH v2 1/3] btrfs: scrub: maintain the unlock order in scrub thread Anand Jain @ 2018-11-29 10:36 ` Filipe Manana 2018-11-30 1:00 ` Anand Jain 0 siblings, 1 reply; 6+ messages in thread From: Filipe Manana @ 2018-11-29 10:36 UTC (permalink / raw) To: Anand Jain; +Cc: linux-btrfs On Thu, Nov 29, 2018 at 9:27 AM Anand Jain <anand.jain@oracle.com> wrote: > > The device_list_mutex and scrub_lock creates a nested locks in > btrfs_scrub_dev(). > > During lock the order is device_list_mutex and then scrub_lock, and during > unlock, the order is device_list_mutex and then scrub_lock. > Fix this to the lock order of scrub_lock and then device_list_mutex. > > Signed-off-by: Anand Jain <anand.jain@oracle.com> > --- > v1->v2: change the order of lock acquire first scrub_lock and then > device_list_mutex, which matches with the order of unlock. > The extra line which are now in the scrub_lock are ok to be > under the scrub_lock. I don't get it. What problem does this patch fixes? Doesn't seem any functional fix to me, nor performance gain (by the contrary, the scrub_lock is now held for a longer time than needed), nor makes anything more readable or "beautiful". > fs/btrfs/scrub.c | 13 +++++++------ > 1 file changed, 7 insertions(+), 6 deletions(-) > > diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c > index 902819d3cf41..a9d6fc3b01d4 100644 > --- a/fs/btrfs/scrub.c > +++ b/fs/btrfs/scrub.c > @@ -3813,28 +3813,29 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start, > return -EINVAL; > } > > - > + mutex_lock(&fs_info->scrub_lock); > mutex_lock(&fs_info->fs_devices->device_list_mutex); > dev = btrfs_find_device(fs_info, devid, NULL, NULL); > if (!dev || (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state) && > !is_dev_replace)) { > mutex_unlock(&fs_info->fs_devices->device_list_mutex); > + mutex_unlock(&fs_info->scrub_lock); > return -ENODEV; > } > > if (!is_dev_replace && !readonly && > !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state)) { > mutex_unlock(&fs_info->fs_devices->device_list_mutex); > + mutex_unlock(&fs_info->scrub_lock); > btrfs_err_in_rcu(fs_info, "scrub: device %s is not writable", > rcu_str_deref(dev->name)); > return -EROFS; > } > > - mutex_lock(&fs_info->scrub_lock); > if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &dev->dev_state) || > test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &dev->dev_state)) { > - mutex_unlock(&fs_info->scrub_lock); > mutex_unlock(&fs_info->fs_devices->device_list_mutex); > + mutex_unlock(&fs_info->scrub_lock); > return -EIO; > } > > @@ -3843,23 +3844,23 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start, > (!is_dev_replace && > btrfs_dev_replace_is_ongoing(&fs_info->dev_replace))) { > btrfs_dev_replace_read_unlock(&fs_info->dev_replace); > - mutex_unlock(&fs_info->scrub_lock); > mutex_unlock(&fs_info->fs_devices->device_list_mutex); > + mutex_unlock(&fs_info->scrub_lock); > return -EINPROGRESS; > } > btrfs_dev_replace_read_unlock(&fs_info->dev_replace); > > ret = scrub_workers_get(fs_info, is_dev_replace); > if (ret) { > - mutex_unlock(&fs_info->scrub_lock); > mutex_unlock(&fs_info->fs_devices->device_list_mutex); > + mutex_unlock(&fs_info->scrub_lock); > return ret; > } > > sctx = scrub_setup_ctx(dev, is_dev_replace); > if (IS_ERR(sctx)) { > - mutex_unlock(&fs_info->scrub_lock); > mutex_unlock(&fs_info->fs_devices->device_list_mutex); > + mutex_unlock(&fs_info->scrub_lock); > scrub_workers_put(fs_info); > return PTR_ERR(sctx); > } > -- > 1.8.3.1 -- Filipe David Manana, “Whether you think you can, or you think you can't — you're right.” ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2 1/3] btrfs: scrub: maintain the unlock order in scrub thread 2018-11-29 10:36 ` Filipe Manana @ 2018-11-30 1:00 ` Anand Jain 0 siblings, 0 replies; 6+ messages in thread From: Anand Jain @ 2018-11-30 1:00 UTC (permalink / raw) To: fdmanana; +Cc: linux-btrfs On 11/29/2018 06:36 PM, Filipe Manana wrote: > On Thu, Nov 29, 2018 at 9:27 AM Anand Jain <anand.jain@oracle.com> wrote: >> >> The device_list_mutex and scrub_lock creates a nested locks in >> btrfs_scrub_dev(). >> >> During lock the order is device_list_mutex and then scrub_lock, and during >> unlock, the order is device_list_mutex and then scrub_lock. >> Fix this to the lock order of scrub_lock and then device_list_mutex. >> >> Signed-off-by: Anand Jain <anand.jain@oracle.com> >> --- >> v1->v2: change the order of lock acquire first scrub_lock and then >> device_list_mutex, which matches with the order of unlock. >> The extra line which are now in the scrub_lock are ok to be >> under the scrub_lock. > > I don't get it. > What problem does this patch fixes? > Doesn't seem any functional fix to me, nor performance gain (by the > contrary, the scrub_lock is now held for a longer time than needed), > nor makes anything more readable or "beautiful". btrfs_scrub_dev() isn't following the lock and unlock FILO order. Such as lock-a lock-b .. unlock-b unlock-a. So this patch is trying to fix it. This patch fixes the order but I think you mean to say as __scrub_blocked_if_needed() calls unlock scrub_lock. oops my bad this patch is wrong. Scrub concurrency needs overhaul including the dependency on the user land btrfs-progs, which I was trying to avoid. but looks like its better to fix that as well. As of now I am NACK this patch. Thanks, Anand >> fs/btrfs/scrub.c | 13 +++++++------ >> 1 file changed, 7 insertions(+), 6 deletions(-) >> >> diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c >> index 902819d3cf41..a9d6fc3b01d4 100644 >> --- a/fs/btrfs/scrub.c >> +++ b/fs/btrfs/scrub.c >> @@ -3813,28 +3813,29 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start, >> return -EINVAL; >> } >> >> - >> + mutex_lock(&fs_info->scrub_lock); >> mutex_lock(&fs_info->fs_devices->device_list_mutex); >> dev = btrfs_find_device(fs_info, devid, NULL, NULL); >> if (!dev || (test_bit(BTRFS_DEV_STATE_MISSING, &dev->dev_state) && >> !is_dev_replace)) { >> mutex_unlock(&fs_info->fs_devices->device_list_mutex); >> + mutex_unlock(&fs_info->scrub_lock); >> return -ENODEV; >> } >> >> if (!is_dev_replace && !readonly && >> !test_bit(BTRFS_DEV_STATE_WRITEABLE, &dev->dev_state)) { >> mutex_unlock(&fs_info->fs_devices->device_list_mutex); >> + mutex_unlock(&fs_info->scrub_lock); >> btrfs_err_in_rcu(fs_info, "scrub: device %s is not writable", >> rcu_str_deref(dev->name)); >> return -EROFS; >> } >> >> - mutex_lock(&fs_info->scrub_lock); >> if (!test_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &dev->dev_state) || >> test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &dev->dev_state)) { >> - mutex_unlock(&fs_info->scrub_lock); >> mutex_unlock(&fs_info->fs_devices->device_list_mutex); >> + mutex_unlock(&fs_info->scrub_lock); >> return -EIO; >> } >> >> @@ -3843,23 +3844,23 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start, >> (!is_dev_replace && >> btrfs_dev_replace_is_ongoing(&fs_info->dev_replace))) { >> btrfs_dev_replace_read_unlock(&fs_info->dev_replace); >> - mutex_unlock(&fs_info->scrub_lock); >> mutex_unlock(&fs_info->fs_devices->device_list_mutex); >> + mutex_unlock(&fs_info->scrub_lock); >> return -EINPROGRESS; >> } >> btrfs_dev_replace_read_unlock(&fs_info->dev_replace); >> >> ret = scrub_workers_get(fs_info, is_dev_replace); >> if (ret) { >> - mutex_unlock(&fs_info->scrub_lock); >> mutex_unlock(&fs_info->fs_devices->device_list_mutex); >> + mutex_unlock(&fs_info->scrub_lock); >> return ret; >> } >> >> sctx = scrub_setup_ctx(dev, is_dev_replace); >> if (IS_ERR(sctx)) { >> - mutex_unlock(&fs_info->scrub_lock); >> mutex_unlock(&fs_info->fs_devices->device_list_mutex); >> + mutex_unlock(&fs_info->scrub_lock); >> scrub_workers_put(fs_info); >> return PTR_ERR(sctx); >> } >> -- >> 1.8.3.1 > > > ^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v2 2/3] btrfs: scrub: fix circular locking dependency warning 2018-11-29 9:25 [PATCH v2 0/3] btrfs: scrub: fix scrub_lock Anand Jain 2018-11-29 9:25 ` [PATCH v2 1/3] btrfs: scrub: maintain the unlock order in scrub thread Anand Jain @ 2018-11-29 9:25 ` Anand Jain 2018-11-29 9:25 ` [PATCH v2 3/3] btrfs: scrub: add scrub_lock lockdep check in scrub_workers_get Anand Jain 2 siblings, 0 replies; 6+ messages in thread From: Anand Jain @ 2018-11-29 9:25 UTC (permalink / raw) To: linux-btrfs Circular locking dependency check reports warning[1], that's because the btrfs_scrub_dev() calls the stack #0 below with, the fs_info::scrub_lock held. The test case leading to this warning.. mkfs.btrfs -fq /dev/sdb && mount /dev/sdb /btrfs btrfs scrub start -B /btrfs In fact we have fs_info::scrub_workers_refcnt to tack if the init and destroy of the scrub workers are needed. So once we have incremented and decremented the fs_info::scrub_workers_refcnt value in the thread, its ok to drop the scrub_lock, and then actually do the btrfs_destroy_workqueue() part. So this patch drops the scrub_lock before calling btrfs_destroy_workqueue(). [1] [ 76.146826] ====================================================== [ 76.147086] WARNING: possible circular locking dependency detected [ 76.147316] 4.20.0-rc3+ #41 Not tainted [ 76.147489] ------------------------------------------------------ [ 76.147722] btrfs/4065 is trying to acquire lock: [ 76.147984] 0000000038593bc0 ((wq_completion)"%s-%s""btrfs", name){+.+.}, at: flush_workqueue+0x70/0x4d0 [ 76.148337] but task is already holding lock: [ 76.148594] 0000000062392ab7 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x316/0x5d0 [btrfs] [ 76.148909] which lock already depends on the new lock. [ 76.149191] the existing dependency chain (in reverse order) is: [ 76.149446] -> #3 (&fs_info->scrub_lock){+.+.}: [ 76.149707] btrfs_scrub_dev+0x11f/0x5d0 [btrfs] [ 76.149924] btrfs_ioctl+0x1ac3/0x2d80 [btrfs] [ 76.150216] do_vfs_ioctl+0xa9/0x6d0 [ 76.150468] ksys_ioctl+0x60/0x90 [ 76.150716] __x64_sys_ioctl+0x16/0x20 [ 76.150911] do_syscall_64+0x50/0x180 [ 76.151182] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 76.151469] -> #2 (&fs_devs->device_list_mutex){+.+.}: [ 76.151851] reada_start_machine_worker+0xca/0x3f0 [btrfs] [ 76.152195] normal_work_helper+0xf0/0x4c0 [btrfs] [ 76.152489] process_one_work+0x1f4/0x520 [ 76.152751] worker_thread+0x46/0x3d0 [ 76.153715] kthread+0xf8/0x130 [ 76.153912] ret_from_fork+0x3a/0x50 [ 76.154178] -> #1 ((work_completion)(&work->normal_work)){+.+.}: [ 76.154575] worker_thread+0x46/0x3d0 [ 76.154828] kthread+0xf8/0x130 [ 76.155108] ret_from_fork+0x3a/0x50 [ 76.155357] -> #0 ((wq_completion)"%s-%s""btrfs", name){+.+.}: [ 76.155751] flush_workqueue+0x9a/0x4d0 [ 76.155911] drain_workqueue+0xca/0x1a0 [ 76.156182] destroy_workqueue+0x17/0x230 [ 76.156455] btrfs_destroy_workqueue+0x5d/0x1c0 [btrfs] [ 76.156756] scrub_workers_put+0x2e/0x60 [btrfs] [ 76.156931] btrfs_scrub_dev+0x329/0x5d0 [btrfs] [ 76.157219] btrfs_ioctl+0x1ac3/0x2d80 [btrfs] [ 76.157491] do_vfs_ioctl+0xa9/0x6d0 [ 76.157742] ksys_ioctl+0x60/0x90 [ 76.157910] __x64_sys_ioctl+0x16/0x20 [ 76.158177] do_syscall_64+0x50/0x180 [ 76.158429] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 76.158716] other info that might help us debug this: [ 76.158908] Chain exists of: (wq_completion)"%s-%s""btrfs", name --> &fs_devs->device_list_mutex --> &fs_info->scrub_lock [ 76.159629] Possible unsafe locking scenario: [ 76.160607] CPU0 CPU1 [ 76.160934] ---- ---- [ 76.161210] lock(&fs_info->scrub_lock); [ 76.161458] lock(&fs_devs->device_list_mutex); [ 76.161805] lock(&fs_info->scrub_lock); [ 76.161909] lock((wq_completion)"%s-%s""btrfs", name); [ 76.162201] *** DEADLOCK *** [ 76.162627] 2 locks held by btrfs/4065: [ 76.162897] #0: 00000000bef2775b (sb_writers#12){.+.+}, at: mnt_want_write_file+0x24/0x50 [ 76.163335] #1: 0000000062392ab7 (&fs_info->scrub_lock){+.+.}, at: btrfs_scrub_dev+0x316/0x5d0 [btrfs] [ 76.163796] stack backtrace: [ 76.163911] CPU: 1 PID: 4065 Comm: btrfs Not tainted 4.20.0-rc3+ #41 [ 76.164228] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006 [ 76.164646] Call Trace: [ 76.164872] dump_stack+0x5e/0x8b [ 76.165128] print_circular_bug.isra.37+0x1f1/0x1fe [ 76.165398] __lock_acquire+0x14aa/0x1620 [ 76.165652] lock_acquire+0xb0/0x190 [ 76.165910] ? flush_workqueue+0x70/0x4d0 [ 76.166175] flush_workqueue+0x9a/0x4d0 [ 76.166420] ? flush_workqueue+0x70/0x4d0 [ 76.166671] ? drain_workqueue+0x52/0x1a0 [ 76.166911] drain_workqueue+0xca/0x1a0 [ 76.167167] destroy_workqueue+0x17/0x230 [ 76.167428] btrfs_destroy_workqueue+0x5d/0x1c0 [btrfs] [ 76.167720] scrub_workers_put+0x2e/0x60 [btrfs] [ 76.168233] btrfs_scrub_dev+0x329/0x5d0 [btrfs] [ 76.168504] ? __sb_start_write+0x121/0x1b0 [ 76.168759] ? mnt_want_write_file+0x24/0x50 [ 76.169654] btrfs_ioctl+0x1ac3/0x2d80 [btrfs] [ 76.169934] ? find_held_lock+0x2d/0x90 [ 76.170204] ? find_held_lock+0x2d/0x90 [ 76.170450] do_vfs_ioctl+0xa9/0x6d0 [ 76.170690] ? __fget+0x101/0x1f0 [ 76.170910] ? __fget+0x5/0x1f0 [ 76.171157] ksys_ioctl+0x60/0x90 [ 76.171391] __x64_sys_ioctl+0x16/0x20 [ 76.171634] do_syscall_64+0x50/0x180 [ 76.171892] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 76.172186] RIP: 0033:0x7f61d422e567 [ 76.172425] Code: 44 00 00 48 8b 05 29 09 2d 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d f9 08 2d 00 f7 d8 64 89 01 48 [ 76.172911] RSP: 002b:00007f61d3936d68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 76.173328] RAX: ffffffffffffffda RBX: 00000000019026b0 RCX: 00007f61d422e567 [ 76.173649] RDX: 00000000019026b0 RSI: 00000000c400941b RDI: 0000000000000003 [ 76.173909] RBP: 0000000000000000 R08: 00007f61d3937700 R09: 0000000000000000 [ 76.174244] R10: 00007f61d3937700 R11: 0000000000000246 R12: 0000000000000000 [ 76.174566] R13: 0000000000801000 R14: 0000000000000000 R15: 00007f61d3937700 [ 76.175217] btrfs (4065) used greatest stack depth: 11424 bytes left Signed-off-by: Anand Jain <anand.jain@oracle.com> --- v1->v2: none fs/btrfs/scrub.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index b5a19ba38ab7..9ade0659f017 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -3757,10 +3757,13 @@ static noinline_for_stack int scrub_workers_get(struct btrfs_fs_info *fs_info, static noinline_for_stack void scrub_workers_put(struct btrfs_fs_info *fs_info) { + lockdep_assert_held(&fs_info->scrub_lock); if (--fs_info->scrub_workers_refcnt == 0) { + mutex_unlock(&fs_info->scrub_lock); btrfs_destroy_workqueue(fs_info->scrub_workers); btrfs_destroy_workqueue(fs_info->scrub_wr_completion_workers); btrfs_destroy_workqueue(fs_info->scrub_parity_workers); + mutex_lock(&fs_info->scrub_lock); } WARN_ON(fs_info->scrub_workers_refcnt < 0); } -- 1.8.3.1 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH v2 3/3] btrfs: scrub: add scrub_lock lockdep check in scrub_workers_get 2018-11-29 9:25 [PATCH v2 0/3] btrfs: scrub: fix scrub_lock Anand Jain 2018-11-29 9:25 ` [PATCH v2 1/3] btrfs: scrub: maintain the unlock order in scrub thread Anand Jain 2018-11-29 9:25 ` [PATCH v2 2/3] btrfs: scrub: fix circular locking dependency warning Anand Jain @ 2018-11-29 9:25 ` Anand Jain 2 siblings, 0 replies; 6+ messages in thread From: Anand Jain @ 2018-11-29 9:25 UTC (permalink / raw) To: linux-btrfs scrub_workers_refcnt is protected by scrub_lock, add lockdep_assert_held() function in scrub_workers_get(). Signed-off-by: Anand Jain <anand.jain@oracle.com> Suggested-by: Nikolay Borisov <nborisov@suse.com> --- v2: born fs/btrfs/scrub.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index 9ade0659f017..84ef1f0d371e 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -3726,6 +3726,8 @@ static noinline_for_stack int scrub_workers_get(struct btrfs_fs_info *fs_info, unsigned int flags = WQ_FREEZABLE | WQ_UNBOUND; int max_active = fs_info->thread_pool_size; + lockdep_assert_held(&fs_info->scrub_lock); + if (fs_info->scrub_workers_refcnt == 0) { fs_info->scrub_workers = btrfs_alloc_workqueue(fs_info, "scrub", flags, is_dev_replace ? 1 : max_active, 4); -- 1.8.3.1 ^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2018-11-30 1:00 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2018-11-29 9:25 [PATCH v2 0/3] btrfs: scrub: fix scrub_lock Anand Jain 2018-11-29 9:25 ` [PATCH v2 1/3] btrfs: scrub: maintain the unlock order in scrub thread Anand Jain 2018-11-29 10:36 ` Filipe Manana 2018-11-30 1:00 ` Anand Jain 2018-11-29 9:25 ` [PATCH v2 2/3] btrfs: scrub: fix circular locking dependency warning Anand Jain 2018-11-29 9:25 ` [PATCH v2 3/3] btrfs: scrub: add scrub_lock lockdep check in scrub_workers_get Anand Jain
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