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8876391e44
linux/drivers/md
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BingJing Chang 8876391e44 md: fix a potential deadlock of raid5/raid10 reshape 
There is a potential deadlock if mount/umount happens when
raid5_finish_reshape() tries to grow the size of emulated disk.

How the deadlock happens?
1) The raid5 resync thread finished reshape (expanding array).
2) The mount or umount thread holds VFS sb->s_umount lock and tries to
   write through critical data into raid5 emulated block device. So it
   waits for raid5 kernel thread handling stripes in order to finish it
   I/Os.
3) In the routine of raid5 kernel thread, md_check_recovery() will be
   called first in order to reap the raid5 resync thread. That is,
   raid5_finish_reshape() will be called. In this function, it will try
   to update conf and call VFS revalidate_disk() to grow the raid5
   emulated block device. It will try to acquire VFS sb->s_umount lock.
The raid5 kernel thread cannot continue, so no one can handle mount/
umount I/Os (stripes). Once the write-through I/Os cannot be finished,
mount/umount will not release sb->s_umount lock. The deadlock happens.

The raid5 kernel thread is an emulated block device. It is responible to
handle I/Os (stripes) from upper layers. The emulated block device
should not request any I/Os on itself. That is, it should not call VFS
layer functions. (If it did, it will try to acquire VFS locks to
guarantee the I/Os sequence.) So we have the resync thread to send
resync I/O requests and to wait for the results.

For solving this potential deadlock, we can put the size growth of the
emulated block device as the final step of reshape thread.

2017/12/29:
Thanks to Guoqing Jiang <gqjiang@suse.com>,
we confirmed that there is the same deadlock issue in raid10. It's
reproducible and can be fixed by this patch. For raid10.c, we can remove
the similar code to prevent deadlock as well since they has been called
before.

Reported-by: Alex Wu <alexwu@synology.com>
Reviewed-by: Alex Wu <alexwu@synology.com>
Reviewed-by: Chung-Chiang Cheng <cccheng@synology.com>
Signed-off-by: BingJing Chang <bingjingc@synology.com>
Signed-off-by: Shaohua Li <sh.li@alibaba-inc.com>
2018-02-25 10:39:15 -08:00
..
bcache bcache: fix for data collapse after re-attaching an attached device 2018-02-07 12:50:01 -07:00
persistent-data dm btree: fix serious bug in btree_split_beneath() 2018-01-17 09:07:55 -05:00
dm-bio-prison-v1.c dm bio prison: use rb_entry() rather than container_of() 2017-06-19 11:03:50 -04:00
dm-bio-prison-v1.h block: switch bios to blk_status_t 2017-06-09 09:27:32 -06:00
dm-bio-prison-v2.c dm bio prison: use rb_entry() rather than container_of() 2017-06-19 11:03:50 -04:00
dm-bio-prison-v2.h dm bio prison v2: new interface for the bio prison 2017-03-07 11:30:16 -05:00
dm-bio-record.h block: replace bi_bdev with a gendisk pointer and partitions index 2017-08-23 12:49:55 -06:00
dm-bufio.c dm bufio: eliminate unnecessary labels in dm_bufio_client_create() 2018-01-17 09:16:04 -05:00
dm-bufio.h dm integrity: optimize writing dm-bufio buffers that are partially changed 2017-08-28 11:47:17 -04:00
dm-builtin.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
dm-cache-background-tracker.c dm cache background tracker: limit amount of background work that may be issued at once 2017-11-10 15:45:03 -05:00
dm-cache-background-tracker.h dm cache: significant rework to leverage dm-bio-prison-v2 2017-03-07 13:28:31 -05:00
dm-cache-block-types.h linux: drop __bitwise__ everywhere 2016-12-16 00:13:41 +02:00
dm-cache-metadata.c dm cache: convert dm_cache_metadata.ref_count from atomic_t to refcount_t 2017-10-24 15:09:51 -04:00
dm-cache-metadata.h dm cache: significant rework to leverage dm-bio-prison-v2 2017-03-07 13:28:31 -05:00
dm-cache-policy-internal.h dm cache: significant rework to leverage dm-bio-prison-v2 2017-03-07 13:28:31 -05:00
dm-cache-policy-smq.c dm cache policy smq: allocate cache blocks in order 2017-11-10 15:45:05 -05:00
dm-cache-policy.c
dm-cache-policy.h dm cache: significant rework to leverage dm-bio-prison-v2 2017-03-07 13:28:31 -05:00
dm-cache-target.c dm: fix various targets to dm_register_target after module __init resources created 2017-12-04 10:23:10 -05:00
dm-core.h dm: various cleanups to md->queue initialization code 2018-01-29 13:44:55 -05:00
dm-crypt.c - DM core fixes to ensure that bio submission follows a depth-first tree 2018-01-31 11:05:47 -08:00
dm-delay.c dm: backfill missing calls to mutex_destroy() 2018-01-17 09:16:15 -05:00
dm-era-target.c dm: do not set 'discards_supported' in targets that do not need it 2017-11-16 16:33:54 -05:00
dm-exception-store.c
dm-exception-store.h
dm-flakey.c dm flakey: check for null arg_name in parse_features() 2018-01-17 09:16:13 -05:00
dm-integrity.c dm integrity: don't store cipher request on the stack 2018-01-17 09:08:57 -05:00
dm-io.c dm io: remove BIOSET_NEED_RESCUER flag from bios bioset 2017-12-13 12:15:56 -05:00
dm-ioctl.c vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
dm-kcopyd.c dm: backfill missing calls to mutex_destroy() 2018-01-17 09:16:15 -05:00
dm-linear.c - Some request-based DM core and DM multipath fixes and cleanups 2017-09-14 13:43:16 -07:00
dm-log-userspace-base.c
dm-log-userspace-transfer.c
dm-log-userspace-transfer.h
dm-log-writes.c dm log writes: fix max length used for kstrndup 2018-01-17 09:16:16 -05:00
dm-log.c block,fs: use REQ_* flags directly 2016-11-01 09:43:26 -06:00
dm-mpath.c - DM core fixes to ensure that bio submission follows a depth-first tree 2018-01-31 11:05:47 -08:00
dm-mpath.h
dm-path-selector.c
dm-path-selector.h
dm-queue-length.c dm mpath selector: more evenly distribute ties 2018-01-29 13:44:58 -05:00
dm-raid1.c md: Convert timers to use timer_setup() 2017-11-14 20:11:57 -07:00
dm-raid.c - DM core fixes to ensure that bio submission follows a depth-first tree 2018-01-31 11:05:47 -08:00
dm-region-hash.c
dm-round-robin.c dm round robin: revert "use percpu 'repeat_count' and 'current_path'" 2017-02-17 00:54:09 -05:00
dm-rq.c for-linus-20180204 2018-02-04 11:16:35 -08:00
dm-rq.h dm rq: do not update rq partially in each ending bio 2017-08-28 10:23:28 -04:00
dm-service-time.c dm mpath selector: more evenly distribute ties 2018-01-29 13:44:58 -05:00
dm-snap-persistent.c dm: make flush bios explicitly sync 2017-05-31 10:50:23 -04:00
dm-snap-transient.c
dm-snap.c dm snapshot: use mutex instead of rw_semaphore 2018-01-17 09:16:14 -05:00
dm-stats.c dm: backfill missing calls to mutex_destroy() 2018-01-17 09:16:15 -05:00
dm-stats.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
dm-stripe.c - Some request-based DM core and DM multipath fixes and cleanups 2017-09-14 13:43:16 -07:00
dm-switch.c locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE() 2017-10-25 11:01:08 +02:00
dm-sysfs.c
dm-table.c dm table: fix NVMe bio-based dm_table_determine_type() validation 2018-01-29 13:44:56 -05:00
dm-target.c dm: don't return errnos from ->map 2017-06-09 09:27:32 -06:00
dm-thin-metadata.c dm thin metadata: THIN_MAX_CONCURRENT_LOCKS should be 6 2018-01-17 09:07:54 -05:00
dm-thin-metadata.h
dm-thin.c dm thin: fix trailing semicolon in __remap_and_issue_shared_cell 2018-01-29 13:44:57 -05:00
dm-uevent.c
dm-uevent.h
dm-unstripe.c dm unstripe: fix target length versus number of stripes size check 2018-01-29 13:44:58 -05:00
dm-verity-fec.c dm verity fec: fix GFP flags used with mempool_alloc() 2017-07-26 15:55:44 -04:00
dm-verity-fec.h dm verity fec: limit error correction recursion 2017-03-16 09:37:31 -04:00
dm-verity-target.c Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-11-14 10:52:09 -08:00
dm-verity.h dm: move dm-verity to generic async completion 2017-11-03 22:11:20 +08:00
dm-zero.c dm: don't return errnos from ->map 2017-06-09 09:27:32 -06:00
dm-zoned-metadata.c dm: backfill missing calls to mutex_destroy() 2018-01-17 09:16:15 -05:00
dm-zoned-reclaim.c dm zoned: use GFP_NOIO in I/O path 2017-07-26 15:55:43 -04:00
dm-zoned-target.c dm: backfill missing calls to mutex_destroy() 2018-01-17 09:16:15 -05:00
dm-zoned.h dm zoned: drive-managed zoned block device target 2017-06-19 11:05:20 -04:00
dm.c dm: correctly handle chained bios in dec_pending() 2018-02-16 10:46:35 -05:00
dm.h dm: move dm_table_destroy() to same header as dm_table_create() 2018-01-17 09:16:06 -05:00
Kconfig dm: add unstriped target 2018-01-17 09:16:00 -05:00
Makefile dm: add unstriped target 2018-01-17 09:16:00 -05:00
md-bitmap.c Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md 2017-11-14 16:07:26 -08:00
md-bitmap.h Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md 2017-11-14 16:07:26 -08:00
md-cluster.c md-cluster: update document for raid10 2017-11-01 21:32:25 -07:00
md-cluster.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
md-faulty.c md: rename some drivers/md/ files to have an "md-" prefix 2017-10-16 19:06:36 -07:00
md-linear.c md: rename some drivers/md/ files to have an "md-" prefix 2017-10-16 19:06:36 -07:00
md-linear.h Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md 2017-11-14 16:07:26 -08:00
md-multipath.c md-multipath: Use seq_putc() in multipath_status() 2018-02-17 13:00:35 -08:00
md-multipath.h Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md 2017-11-14 16:07:26 -08:00
md.c md: fix a potential deadlock of raid5/raid10 reshape 2018-02-25 10:39:15 -08:00
md.h md: fix md_write_start() deadlock w/o metadata devices 2018-02-18 10:11:59 -08:00
raid0.c md: remove special meaning of ->quiesce(.., 2) 2017-11-01 21:32:20 -07:00
raid0.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
raid1-10.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
raid1.c md/raid1: Fix trailing semicolon 2018-02-17 12:58:29 -08:00
raid1.h md: document lifetime of internal rdev pointer. 2018-02-18 10:22:27 -08:00
raid5-cache.c raid5-ppl: PPL support for disks with write-back cache enabled 2018-01-15 14:29:42 -08:00
raid5-log.h raid5-ppl: fix handling flush requests 2018-02-21 09:40:40 -08:00
raid5-ppl.c raid5-ppl: fix handling flush requests 2018-02-21 09:40:40 -08:00
raid5.c md: fix a potential deadlock of raid5/raid10 reshape 2018-02-25 10:39:15 -08:00
raid5.h md: document lifetime of internal rdev pointer. 2018-02-18 10:22:27 -08:00
raid10.c md: fix a potential deadlock of raid5/raid10 reshape 2018-02-25 10:39:15 -08:00
raid10.h md: document lifetime of internal rdev pointer. 2018-02-18 10:22:27 -08:00