kernel/linux.git/drivers/md/md.c, branch v5.4.50

md: don't flush workqueue unconditionally in md_open

2020-06-22T07:31:05+00:00

[ Upstream commit f6766ff6afff70e2aaf39e1511e16d471de7c3ae ] We need to check mddev->del_work before flush workqueu since the purpose of flush is to ensure the previous md is disappeared. Otherwise the similar deadlock appeared if LOCKDEP is enabled, it is due to md_open holds the bdev->bd_mutex before flush workqueue. kernel: [ 154.522645] ====================================================== kernel: [ 154.522647] WARNING: possible circular locking dependency detected kernel: [ 154.522650] 5.6.0-rc7-lp151.27-default #25 Tainted: G O kernel: [ 154.522651] ------------------------------------------------------ kernel: [ 154.522653] mdadm/2482 is trying to acquire lock: kernel: [ 154.522655] ffff888078529128 ((wq_completion)md_misc){+.+.}, at: flush_workqueue+0x84/0x4b0 kernel: [ 154.522673] kernel: [ 154.522673] but task is already holding lock: kernel: [ 154.522675] ffff88804efa9338 (&bdev->bd_mutex){+.+.}, at: __blkdev_get+0x79/0x590 kernel: [ 154.522691] kernel: [ 154.522691] which lock already depends on the new lock. kernel: [ 154.522691] kernel: [ 154.522694] kernel: [ 154.522694] the existing dependency chain (in reverse order) is: kernel: [ 154.522696] kernel: [ 154.522696] -> #4 (&bdev->bd_mutex){+.+.}: kernel: [ 154.522704] __mutex_lock+0x87/0x950 kernel: [ 154.522706] __blkdev_get+0x79/0x590 kernel: [ 154.522708] blkdev_get+0x65/0x140 kernel: [ 154.522709] blkdev_get_by_dev+0x2f/0x40 kernel: [ 154.522716] lock_rdev+0x3d/0x90 [md_mod] kernel: [ 154.522719] md_import_device+0xd6/0x1b0 [md_mod] kernel: [ 154.522723] new_dev_store+0x15e/0x210 [md_mod] kernel: [ 154.522728] md_attr_store+0x7a/0xc0 [md_mod] kernel: [ 154.522732] kernfs_fop_write+0x117/0x1b0 kernel: [ 154.522735] vfs_write+0xad/0x1a0 kernel: [ 154.522737] ksys_write+0xa4/0xe0 kernel: [ 154.522745] do_syscall_64+0x64/0x2b0 kernel: [ 154.522748] entry_SYSCALL_64_after_hwframe+0x49/0xbe kernel: [ 154.522749] kernel: [ 154.522749] -> #3 (&mddev->reconfig_mutex){+.+.}: kernel: [ 154.522752] __mutex_lock+0x87/0x950 kernel: [ 154.522756] new_dev_store+0xc9/0x210 [md_mod] kernel: [ 154.522759] md_attr_store+0x7a/0xc0 [md_mod] kernel: [ 154.522761] kernfs_fop_write+0x117/0x1b0 kernel: [ 154.522763] vfs_write+0xad/0x1a0 kernel: [ 154.522765] ksys_write+0xa4/0xe0 kernel: [ 154.522767] do_syscall_64+0x64/0x2b0 kernel: [ 154.522769] entry_SYSCALL_64_after_hwframe+0x49/0xbe kernel: [ 154.522770] kernel: [ 154.522770] -> #2 (kn->count#253){++++}: kernel: [ 154.522775] __kernfs_remove+0x253/0x2c0 kernel: [ 154.522778] kernfs_remove+0x1f/0x30 kernel: [ 154.522780] kobject_del+0x28/0x60 kernel: [ 154.522783] mddev_delayed_delete+0x24/0x30 [md_mod] kernel: [ 154.522786] process_one_work+0x2a7/0x5f0 kernel: [ 154.522788] worker_thread+0x2d/0x3d0 kernel: [ 154.522793] kthread+0x117/0x130 kernel: [ 154.522795] ret_from_fork+0x3a/0x50 kernel: [ 154.522796] kernel: [ 154.522796] -> #1 ((work_completion)(&mddev->del_work)){+.+.}: kernel: [ 154.522800] process_one_work+0x27e/0x5f0 kernel: [ 154.522802] worker_thread+0x2d/0x3d0 kernel: [ 154.522804] kthread+0x117/0x130 kernel: [ 154.522806] ret_from_fork+0x3a/0x50 kernel: [ 154.522807] kernel: [ 154.522807] -> #0 ((wq_completion)md_misc){+.+.}: kernel: [ 154.522813] __lock_acquire+0x1392/0x1690 kernel: [ 154.522816] lock_acquire+0xb4/0x1a0 kernel: [ 154.522818] flush_workqueue+0xab/0x4b0 kernel: [ 154.522821] md_open+0xb6/0xc0 [md_mod] kernel: [ 154.522823] __blkdev_get+0xea/0x590 kernel: [ 154.522825] blkdev_get+0x65/0x140 kernel: [ 154.522828] do_dentry_open+0x1d1/0x380 kernel: [ 154.522831] path_openat+0x567/0xcc0 kernel: [ 154.522834] do_filp_open+0x9b/0x110 kernel: [ 154.522836] do_sys_openat2+0x201/0x2a0 kernel: [ 154.522838] do_sys_open+0x57/0x80 kernel: [ 154.522840] do_syscall_64+0x64/0x2b0 kernel: [ 154.522842] entry_SYSCALL_64_after_hwframe+0x49/0xbe kernel: [ 154.522844] kernel: [ 154.522844] other info that might help us debug this: kernel: [ 154.522844] kernel: [ 154.522846] Chain exists of: kernel: [ 154.522846] (wq_completion)md_misc --> &mddev->reconfig_mutex --> &bdev->bd_mutex kernel: [ 154.522846] kernel: [ 154.522850] Possible unsafe locking scenario: kernel: [ 154.522850] kernel: [ 154.522852] CPU0 CPU1 kernel: [ 154.522853] ---- ---- kernel: [ 154.522854] lock(&bdev->bd_mutex); kernel: [ 154.522856] lock(&mddev->reconfig_mutex); kernel: [ 154.522858] lock(&bdev->bd_mutex); kernel: [ 154.522860] lock((wq_completion)md_misc); kernel: [ 154.522861] kernel: [ 154.522861] *** DEADLOCK *** kernel: [ 154.522861] kernel: [ 154.522864] 1 lock held by mdadm/2482: kernel: [ 154.522865] #0: ffff88804efa9338 (&bdev->bd_mutex){+.+.}, at: __blkdev_get+0x79/0x590 kernel: [ 154.522868] kernel: [ 154.522868] stack backtrace: kernel: [ 154.522873] CPU: 1 PID: 2482 Comm: mdadm Tainted: G O 5.6.0-rc7-lp151.27-default #25 kernel: [ 154.522875] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 kernel: [ 154.522878] Call Trace: kernel: [ 154.522881] dump_stack+0x8f/0xcb kernel: [ 154.522884] check_noncircular+0x194/0x1b0 kernel: [ 154.522888] ? __lock_acquire+0x1392/0x1690 kernel: [ 154.522890] __lock_acquire+0x1392/0x1690 kernel: [ 154.522893] lock_acquire+0xb4/0x1a0 kernel: [ 154.522895] ? flush_workqueue+0x84/0x4b0 kernel: [ 154.522898] flush_workqueue+0xab/0x4b0 kernel: [ 154.522900] ? flush_workqueue+0x84/0x4b0 kernel: [ 154.522905] ? md_open+0xb6/0xc0 [md_mod] kernel: [ 154.522908] md_open+0xb6/0xc0 [md_mod] kernel: [ 154.522910] __blkdev_get+0xea/0x590 kernel: [ 154.522912] ? bd_acquire+0xc0/0xc0 kernel: [ 154.522914] blkdev_get+0x65/0x140 kernel: [ 154.522916] ? bd_acquire+0xc0/0xc0 kernel: [ 154.522918] do_dentry_open+0x1d1/0x380 kernel: [ 154.522921] path_openat+0x567/0xcc0 kernel: [ 154.522923] ? __lock_acquire+0x380/0x1690 kernel: [ 154.522926] do_filp_open+0x9b/0x110 kernel: [ 154.522929] ? __alloc_fd+0xe5/0x1f0 kernel: [ 154.522935] ? kmem_cache_alloc+0x28c/0x630 kernel: [ 154.522939] ? do_sys_openat2+0x201/0x2a0 kernel: [ 154.522941] do_sys_openat2+0x201/0x2a0 kernel: [ 154.522944] do_sys_open+0x57/0x80 kernel: [ 154.522946] do_syscall_64+0x64/0x2b0 kernel: [ 154.522948] entry_SYSCALL_64_after_hwframe+0x49/0xbe kernel: [ 154.522951] RIP: 0033:0x7f98d279d9ae And md_alloc also flushed the same workqueue, but the thing is different here. Because all the paths call md_alloc don't hold bdev->bd_mutex, and the flush is necessary to avoid race condition, so leave it as it is. Signed-off-by: Guoqing Jiang Signed-off-by: Song Liu Signed-off-by: Sasha Levin

md: check arrays is suspended in mddev_detach before call quiesce operations

2020-04-17T08:50:04+00:00

[ Upstream commit 6b40bec3b13278d21fa6c1ae7a0bdf2e550eed5f ] Don't call quiesce(1) and quiesce(0) if array is already suspended, otherwise in level_store, the array is writable after mddev_detach in below part though the intention is to make array writable after resume. mddev_suspend(mddev); mddev_detach(mddev); ... mddev_resume(mddev); And it also causes calltrace as follows in [1]. [48005.653834] WARNING: CPU: 1 PID: 45380 at kernel/kthread.c:510 kthread_park+0x77/0x90 [...] [48005.653976] CPU: 1 PID: 45380 Comm: mdadm Tainted: G OE 5.4.10-arch1-1 #1 [48005.653979] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./J4105-ITX, BIOS P1.40 08/06/2018 [48005.653984] RIP: 0010:kthread_park+0x77/0x90 [48005.654015] Call Trace: [48005.654039] r5l_quiesce+0x3c/0x70 [raid456] [48005.654052] raid5_quiesce+0x228/0x2e0 [raid456] [48005.654073] mddev_detach+0x30/0x70 [md_mod] [48005.654090] level_store+0x202/0x670 [md_mod] [48005.654099] ? security_capable+0x40/0x60 [48005.654114] md_attr_store+0x7b/0xc0 [md_mod] [48005.654123] kernfs_fop_write+0xce/0x1b0 [48005.654132] vfs_write+0xb6/0x1a0 [48005.654138] ksys_write+0x67/0xe0 [48005.654146] do_syscall_64+0x4e/0x140 [48005.654155] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [48005.654161] RIP: 0033:0x7fa0c8737497 [1]: https://bugzilla.kernel.org/show_bug.cgi?id=206161 Signed-off-by: Guoqing Jiang Signed-off-by: Song Liu Signed-off-by: Sasha Levin

md: make sure desc_nr less than MD_SB_DISKS

2020-01-04T18:18:34+00:00

[ Upstream commit 3b7436cc9449d5ff7fa1c1fd5bc3edb6402ff5b8 ] For super_90_load, we need to make sure 'desc_nr' less than MD_SB_DISKS, avoiding invalid memory access of 'sb->disks'. Fixes: 228fc7d76db6 ("md: avoid invalid memory access for array sb->dev_roles") Signed-off-by: Yufen Yu Signed-off-by: Song Liu Signed-off-by: Sasha Levin

md: avoid invalid memory access for array sb->dev_roles

2019-12-31T15:46:02+00:00

[ Upstream commit 228fc7d76db68732677230a3c64337908fd298e3 ] we need to gurantee 'desc_nr' valid before access array of sb->dev_roles. In addition, we should avoid .load_super always return '0' when level is LEVEL_MULTIPATH, which is not expected. Reported-by: coverity-bot Addresses-Coverity-ID: 1487373 ("Memory - illegal accesses") Fixes: 6a5cb53aaa4e ("md: no longer compare spare disk superblock events in super_load") Signed-off-by: Yufen Yu Signed-off-by: Song Liu Signed-off-by: Sasha Levin

md: no longer compare spare disk superblock events in super_load

2019-12-31T15:44:19+00:00

[ Upstream commit 6a5cb53aaa4ef515ddeffa04ce18b771121127b4 ] We have a test case as follow: mdadm -CR /dev/md1 -l 1 -n 4 /dev/sd[a-d] \ --assume-clean --bitmap=internal mdadm -S /dev/md1 mdadm -A /dev/md1 /dev/sd[b-c] --run --force mdadm --zero /dev/sda mdadm /dev/md1 -a /dev/sda echo offline > /sys/block/sdc/device/state echo offline > /sys/block/sdb/device/state sleep 5 mdadm -S /dev/md1 echo running > /sys/block/sdb/device/state echo running > /sys/block/sdc/device/state mdadm -A /dev/md1 /dev/sd[a-c] --run --force When we readd /dev/sda to the array, it started to do recovery. After offline the other two disks in md1, the recovery have been interrupted and superblock update info cannot be written to the offline disks. While the spare disk (/dev/sda) can continue to update superblock info. After stopping the array and assemble it, we found the array run fail, with the follow kernel message: [ 172.986064] md: kicking non-fresh sdb from array! [ 173.004210] md: kicking non-fresh sdc from array! [ 173.022383] md/raid1:md1: active with 0 out of 4 mirrors [ 173.022406] md1: failed to create bitmap (-5) [ 173.023466] md: md1 stopped. Since both sdb and sdc have the value of 'sb->events' smaller than that in sda, they have been kicked from the array. However, the only remained disk sda is in 'spare' state before stop and it cannot be added to conf->mirrors[] array. In the end, raid array assemble and run fail. In fact, we can use the older disk sdb or sdc to assemble the array. That means we should not choose the 'spare' disk as the fresh disk in analyze_sbs(). To fix the problem, we do not compare superblock events when it is a spare disk, as same as validate_super. Signed-off-by: Yufen Yu Signed-off-by: Song Liu Signed-off-by: Sasha Levin

md: improve handling of bio with REQ_PREFLUSH in md_flush_request()

2019-12-17T18:56:14+00:00

commit 775d78319f1ceb32be8eb3b1202ccdc60e9cb7f1 upstream. If pers->make_request fails in md_flush_request(), the bio is lost. To fix this, pass back a bool to indicate if the original make_request call should continue to handle the I/O and instead of assuming the flush logic will push it to completion. Convert md_flush_request to return a bool and no longer calls the raid driver's make_request function. If the return is true, then the md flush logic has or will complete the bio and the md make_request call is done. If false, then the md make_request function needs to keep processing like it is a normal bio. Let the original call to md_handle_request handle any need to retry sending the bio to the raid driver's make_request function should it be needed. Also mark md_flush_request and the make_request function pointer as __must_check to issue warnings should these critical return values be ignored. Fixes: 2bc13b83e629 ("md: batch flush requests.") Cc: stable@vger.kernel.org # # v4.19+ Cc: NeilBrown Signed-off-by: David Jeffery Reviewed-by: Xiao Ni Signed-off-by: Song Liu Signed-off-by: Greg Kroah-Hartman

md: add feature flag MD_FEATURE_RAID0_LAYOUT

2019-09-13T20:10:06+00:00

Due to a bug introduced in Linux 3.14 we cannot determine the correctly layout for a multi-zone RAID0 array - there are two possibilities. It is possible to tell the kernel which to chose using a module parameter, but this can be clumsy to use. It would be best if the choice were recorded in the metadata. So add a feature flag for this purpose. If it is set, then the 'layout' field of the superblock is used to determine which layout to use. If this flag is not set, then mddev->layout gets set to -1, which causes the module parameter to be required. Acked-by: Guoqing Jiang Signed-off-by: NeilBrown Signed-off-by: Song Liu

md raid0/linear: Mark array as 'broken' and fail BIOs if a member is gone

2019-09-03T21:49:28+00:00

Currently md raid0/linear are not provided with any mechanism to validate if an array member got removed or failed. The driver keeps sending BIOs regardless of the state of array members, and kernel shows state 'clean' in the 'array_state' sysfs attribute. This leads to the following situation: if a raid0/linear array member is removed and the array is mounted, some user writing to this array won't realize that errors are happening unless they check dmesg or perform one fsync per written file. Despite udev signaling the member device is gone, 'mdadm' cannot issue the STOP_ARRAY ioctl successfully, given the array is mounted. In other words, no -EIO is returned and writes (except direct ones) appear normal. Meaning the user might think the wrote data is correctly stored in the array, but instead garbage was written given that raid0 does stripping (and so, it requires all its members to be working in order to not corrupt data). For md/linear, writes to the available members will work fine, but if the writes go to the missing member(s), it'll cause a file corruption situation, whereas the portion of the writes to the missing devices aren't written effectively. This patch changes this behavior: we check if the block device's gendisk is UP when submitting the BIO to the array member, and if it isn't, we flag the md device as MD_BROKEN and fail subsequent I/Os to that device; a read request to the array requiring data from a valid member is still completed. While flagging the device as MD_BROKEN, we also show a rate-limited warning in the kernel log. A new array state 'broken' was added too: it mimics the state 'clean' in every aspect, being useful only to distinguish if the array has some member missing. We rely on the MD_BROKEN flag to put the array in the 'broken' state. This state cannot be written in 'array_state' as it just shows one or more members of the array are missing but acts like 'clean', it wouldn't make sense to write it. With this patch, the filesystem reacts much faster to the event of missing array member: after some I/O errors, ext4 for instance aborts the journal and prevents corruption. Without this change, we're able to keep writing in the disk and after a machine reboot, e2fsck shows some severe fs errors that demand fixing. This patch was tested in ext4 and xfs filesystems, and requires a 'mdadm' counterpart to handle the 'broken' state. Cc: Song Liu Reviewed-by: NeilBrown Signed-off-by: Guilherme G. Piccoli Signed-off-by: Song Liu

md: don't report active array_state until after revalidate_disk() completes.

2019-08-27T19:36:37+00:00

Until revalidate_disk() has completed, the size of a new md array will appear to be zero. So we shouldn't report, through array_state, that the array is active until that time. udev rules check array_state to see if the array is ready. As soon as it appear to be zero, fsck can be run. If it find the size to be zero, it will fail. So add a new flag to provide an interlock between do_md_run() and array_state_show(). This flag is set while do_md_run() is active and it prevents array_state_show() from reporting that the array is active. Before do_md_run() is called, ->pers will be NULL so array is definitely not active. After do_md_run() is called, revalidate_disk() will have run and the array will be completely ready. We also move various sysfs_notify*() calls out of md_run() into do_md_run() after MD_NOT_READY is cleared. This ensure the information is ready before the notification is sent. Prior to v4.12, array_state_show() was called with the mddev->reconfig_mutex held, which provided exclusion with do_md_run(). Note that MD_NOT_READY cleared twice. This is deliberate to cover both success and error paths with minimal noise. Fixes: b7b17c9b67e5 ("md: remove mddev_lock() from md_attr_show()") Cc: stable@vger.kernel.org (v4.12++) Signed-off-by: NeilBrown Signed-off-by: Song Liu

md: only call set_in_sync() when it is expected to succeed.

2019-08-27T19:36:36+00:00

Since commit 4ad23a976413 ("MD: use per-cpu counter for writes_pending"), set_in_sync() is substantially more expensive: it can wait for a full RCU grace period which can be 10s of milliseconds. So we should only call it when the cost is justified. md_check_recovery() currently calls set_in_sync() every time it finds anything to do (on non-external active arrays). For an array performing resync or recovery, this will be quite often. Each call will introduce a delay to the md thread, which can noticeable affect IO submission latency. In md_check_recovery() we only need to call set_in_sync() if 'safemode' was non-zero at entry, meaning that there has been not recent IO. So we save this "safemode was nonzero" state, and only call set_in_sync() if it was non-zero. This measurably reduces mean and maximum IO submission latency during resync/recovery. Reported-and-tested-by: Jack Wang Fixes: 4ad23a976413 ("MD: use per-cpu counter for writes_pending") Cc: stable@vger.kernel.org (v4.12+) Signed-off-by: NeilBrown Signed-off-by: Song Liu