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81fe48e9aa
linux-next/drivers/md
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NeilBrown 81fe48e9aa md: fix test in md_write_start() 
md_write_start() needs to clear the in_sync flag is it is set, or if
there might be a race with set_in_sync() such that the later will
set it very soon.  In the later case it is sufficient to take the
spinlock to synchronize with set_in_sync(), and then set the flag
if needed.

The current test is incorrect.
It should be:
  if "flag is set" or "race is possible"

"flag is set" is trivially "mddev->in_sync".
"race is possible" should be tested by "mddev->sync_checkers".

If sync_checkers is 0, then there can be no race.  set_in_sync() will
wait in percpu_ref_switch_to_atomic_sync() for an RCU grace period,
and as md_write_start() holds the rcu_read_lock(), set_in_sync() will
be sure ot see the update to writes_pending.

If sync_checkers is > 0, there could be race.  If md_write_start()
happened entirely between
		if (!mddev->in_sync &&
		    percpu_ref_is_zero(&mddev->writes_pending)) {
and
			mddev->in_sync = 1;
in set_in_sync(), then it would not see that is_sync had been set,
and set_in_sync() would not see that writes_pending had been
incremented.

This bug means that in_sync is sometimes not set when it should be.
Consequently there is a small chance that the array will be marked as
"clean" when in fact it is inconsistent.

Fixes: 4ad23a9764 ("MD: use per-cpu counter for writes_pending")
cc: stable@vger.kernel.org (v4.12+)
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>
2017-08-08 07:42:36 -07:00
..
bcache Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-07-03 13:08:04 -07:00
persistent-data dm space map disk: fix some book keeping in the disk space map 2017-05-15 15:09:50 -04:00
bitmap.c md/bitmap: don't read page from device with Bitmap_sync 2017-07-10 10:30:41 -07:00
bitmap.h md: move bitmap_destroy to the beginning of __md_stop 2017-03-16 16:55:58 -07:00
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
dm-bufio.c dm bufio: fix error code in dm_bufio_write_dirty_buffers() 2017-07-25 10:11:15 -04:00
dm-bufio.h dm bufio: add sector start offset to dm-bufio interface 2017-03-07 13:28:33 -05:00
dm-builtin.c dm: move request-based code out to dm-rq.[hc] 2016-06-10 15:15:44 -04:00
dm-cache-background-tracker.c dm cache: handle kmalloc failure allocating background_tracker struct 2017-05-17 09:44:53 -04:00
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 metadata: fail operations if fail_io mode has been established 2017-05-05 14:40:13 -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: don't do any writebacks unless IDLE 2017-05-14 21:54:33 -04:00
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 block: switch bios to blk_status_t 2017-06-09 09:27:32 -06:00
dm-core.h dm: add basic support for using the select or poll function 2017-06-19 11:03:49 -04:00
dm-crypt.c dm crypt: add big-endian variant of plain64 IV 2017-06-19 11:03:50 -04:00
dm-delay.c dm: mark targets that pass integrity data 2017-04-24 12:04:32 -04:00
dm-era-target.c dm block manager: remove an unused argument from dm_block_manager_create() 2017-04-27 17:08:41 -04:00
dm-exception-store.c - Revert a dm-multipath change that caused a regression for unprivledged 2015-11-04 21:19:53 -08:00
dm-exception-store.h dm snapshot: fix hung bios when copy error occurs 2016-01-08 20:03:05 -05:00
dm-flakey.c dm flakey: add support for zoned block devices 2017-06-19 11:03:51 -04:00
dm-integrity.c dm integrity: test for corrupted disk format during table load 2017-07-25 10:11:14 -04:00
dm-io.c Merge branch 'for-4.13/block' of git://git.kernel.dk/linux-block 2017-07-03 10:34:51 -07:00
dm-ioctl.c dm ioctl: report event number in DM_LIST_DEVICES 2017-06-19 11:03:50 -04:00
dm-kcopyd.c dm kcopyd: add sequential write feature 2017-06-19 11:03:51 -04:00
dm-linear.c libnvdimm for 4.13 2017-07-07 09:44:06 -07:00
dm-log-userspace-base.c dm: drop NULL test before kmem_cache_destroy() and mempool_destroy() 2015-10-31 19:06:00 -04:00
dm-log-userspace-transfer.c
dm-log-userspace-transfer.h
dm-log-writes.c block: switch bios to blk_status_t 2017-06-09 09:27:32 -06:00
dm-log.c block,fs: use REQ_* flags directly 2016-11-01 09:43:26 -06:00
dm-mpath.c dm: missing break in process_queued_bios() 2017-06-14 08:22:55 -06:00
dm-mpath.h
dm-path-selector.c
dm-path-selector.h dm path selector: remove 'repeat_count' return from .select_path hook 2016-02-22 22:34:42 -05:00
dm-queue-length.c dm path selector: remove 'repeat_count' return from .select_path hook 2016-02-22 22:34:42 -05:00
dm-raid1.c Merge branch 'for-4.13/block' of git://git.kernel.dk/linux-block 2017-07-03 10:34:51 -07:00
dm-raid.c dm raid: bump target version 2017-07-25 14:54:20 -04:00
dm-region-hash.c block: rename bio bi_rw to bi_opf 2016-08-07 14:41:02 -06:00
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 blk-mq: use the introduced blk_mq_unquiesce_queue() 2017-06-18 14:20:04 -06:00
dm-rq.h block: introduce new block status code type 2017-06-09 09:27:32 -06:00
dm-service-time.c dm path selector: remove 'repeat_count' return from .select_path hook 2016-02-22 22:34:42 -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 snapshot: fix hung bios when copy error occurs 2016-01-08 20:03:05 -05:00
dm-snap.c block: switch bios to blk_status_t 2017-06-09 09:27:32 -06:00
dm-stats.c mm: introduce kv[mz]alloc helpers 2017-05-08 17:15:12 -07:00
dm-stats.h dm stats: support precise timestamps 2015-06-17 12:40:40 -04:00
dm-stripe.c libnvdimm for 4.13 2017-07-07 09:44:06 -07:00
dm-switch.c dm switch: simplify conditional in alloc_region_table() 2015-10-31 19:06:06 -04:00
dm-sysfs.c dm: move request-based code out to dm-rq.[hc] 2016-06-10 15:15:44 -04:00
dm-table.c dm, dax: Make sure dm_dax_flush() is called if device supports it 2017-07-26 15:55:44 -04:00
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: call precommit before saving the roots 2017-05-15 15:09:49 -04:00
dm-thin-metadata.h dm thin: fix a race condition between discarding and provisioning a block 2016-07-20 12:43:35 -04:00
dm-thin.c Merge branch 'for-4.13/block' of git://git.kernel.dk/linux-block 2017-07-03 10:34:51 -07:00
dm-uevent.c
dm-uevent.h
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 Linux 4.12-rc5 2017-06-12 08:30:13 -06:00
dm-verity.h dm verity: switch to using asynchronous hash crypto API 2017-04-24 15:37:04 -04:00
dm-zero.c dm: don't return errnos from ->map 2017-06-09 09:27:32 -06:00
dm-zoned-metadata.c dm zoned: use GFP_NOIO in I/O path 2017-07-26 15:55:43 -04:00
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 zoned: use GFP_NOIO in I/O path 2017-07-26 15:55:43 -04:00
dm-zoned.h dm zoned: drive-managed zoned block device target 2017-06-19 11:05:20 -04:00
dm.c Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2017-07-11 15:36:52 -07:00
dm.h dm: introduce enum dm_queue_mode to cleanup related code 2017-04-27 17:08:44 -04:00
faulty.c md: fix deadlock between mddev_suspend() and md_write_start() 2017-06-13 10:18:01 -07:00
Kconfig dm zoned: drive-managed zoned block device target 2017-06-19 11:05:20 -04:00
linear.c md: fix deadlock between mddev_suspend() and md_write_start() 2017-06-13 10:18:01 -07:00
linear.h md linear: fix a race between linear_add() and linear_congested() 2017-02-13 09:17:50 -08:00
Makefile dm zoned: drive-managed zoned block device target 2017-06-19 11:05:20 -04:00
md-cluster.c md-cluster: fix potential lock issue in add_new_disk 2017-05-21 20:37:09 -07:00
md-cluster.h md-cluster: add the support for resize 2017-03-16 16:55:50 -07:00
md.c md: fix test in md_write_start() 2017-08-08 07:42:36 -07:00
md.h md: raid1-10: move raid1/raid10 common code into raid1-10.c 2017-07-21 12:47:20 -07:00
multipath.c Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md 2017-07-08 12:50:18 -07:00
multipath.h
raid0.c md: fix deadlock between mddev_suspend() and md_write_start() 2017-06-13 10:18:01 -07:00
raid0.h block: kill merge_bvec_fn() completely 2015-08-13 12:31:57 -06:00
raid1-10.c md: raid1-10: move raid1/raid10 common code into raid1-10.c 2017-07-21 12:47:20 -07:00
raid1.c md: simplify code with bio_io_error 2017-07-21 13:16:52 -07:00
raid1.h md/raid1: Use a new variable to count flighting sync requests 2017-04-27 14:01:16 -07:00
raid5-cache.c blk: replace bioset_create_nobvec() with a flags arg to bioset_create() 2017-06-18 12:40:59 -06:00
raid5-log.h md/r5cache: gracefully handle journal device errors for writeback mode 2017-05-11 22:11:11 -07:00
raid5-ppl.c raid5-ppl: use BIOSET_NEED_BVECS when creating bioset 2017-07-12 09:26:37 -07:00
raid5.c md/raid5: add thread_group worker async_tx_issue_pending_all 2017-07-24 07:49:15 -07:00
raid5.h - A major update for DM cache that reduces the latency for deciding 2017-05-03 10:31:20 -07:00
raid10.c md: simplify code with bio_io_error 2017-07-21 13:16:52 -07:00
raid10.h md/raid10: simplify the splitting of requests. 2017-04-11 10:13:02 -07:00