1. 19 Jan, 2017 2 commits
    • Chandan Rajendra's avatar
      Btrfs: Fix deadlock between direct IO and fast fsync · 97dcdea0
      Chandan Rajendra authored
      The following deadlock is seen when executing generic/113 test,
      
       ---------------------------------------------------------+----------------------------------------------------
        Direct I/O task                                           Fast fsync task
       ---------------------------------------------------------+----------------------------------------------------
        btrfs_direct_IO
          __blockdev_direct_IO
           do_blockdev_direct_IO
            do_direct_IO
             btrfs_get_blocks_direct
              while (blocks needs to written)
               get_more_blocks (first iteration)
                btrfs_get_blocks_direct
                 btrfs_create_dio_extent
                   down_read(&BTRFS_I(inode) >dio_sem)
                   Create and add extent map and ordered extent
                   up_read(&BTRFS_I(inode) >dio_sem)
                                                                  btrfs_sync_file
                                                                    btrfs_log_dentry_safe
                                                                     btrfs_log_inode_parent
                                                                      btrfs_log_inode
                                                                       btrfs_log_changed_extents
                                                                        down_write(&BTRFS_I(inode) >dio_sem)
                                                                         Collect new extent maps and ordered extents
                                                                          wait for ordered extent completion
               get_more_blocks (second iteration)
                btrfs_get_blocks_direct
                 btrfs_create_dio_extent
                   down_read(&BTRFS_I(inode) >dio_sem)
       --------------------------------------------------------------------------------------------------------------
      
      In the above description, Btrfs direct I/O code path has not yet started
      submitting bios for file range covered by the initial ordered
      extent. Meanwhile, The fast fsync task obtains the write semaphore and
      waits for I/O on the ordered extent to get completed. However, the
      Direct I/O task is now blocked on obtaining the read semaphore.
      
      To resolve the deadlock, this commit modifies the Direct I/O code path
      to obtain the read semaphore before invoking
      __blockdev_direct_IO(). The semaphore is then given up after
      __blockdev_direct_IO() returns. This allows the Direct I/O code to
      complete I/O on all the ordered extents it creates.
      Signed-off-by: default avatarChandan Rajendra <chandan@linux.vnet.ibm.com>
      Reviewed-by: default avatarFilipe Manana <fdmanana@suse.com>
      Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
      97dcdea0
    • Wang Xiaoguang's avatar
      btrfs: fix false enospc error when truncating heavily reflinked file · 47b5d646
      Wang Xiaoguang authored
      Below test script can reveal this bug:
          dd if=/dev/zero of=fs.img bs=$((1024*1024)) count=100
          dev=$(losetup --show -f fs.img)
          mkdir -p /mnt/mntpoint
          mkfs.btrfs  -f $dev
          mount $dev /mnt/mntpoint
          cd /mnt/mntpoint
      
          echo "workdir is: /mnt/mntpoint"
          blocksize=$((128 * 1024))
          dd if=/dev/zero of=testfile bs=$blocksize count=1
          sync
          count=$((17*1024*1024*1024/blocksize))
          echo "file size is:" $((count*blocksize))
          for ((i = 1; i <= $count; i++)); do
              dst_offset=$((blocksize * i))
              xfs_io -f -c "reflink testfile 0 $dst_offset $blocksize"\
                      testfile > /dev/null
          done
          sync
          truncate --size 0 testfile
      
      The last truncate operation will fail for ENOSPC reason, but indeed
      it should not fail.
      
      In btrfs_truncate(), we use a temporary block_rsv to do truncate
      operation. With every btrfs_truncate_inode_items() call, we migrate space
      to this block_rsv, but forget to cleanup previous reservation, which
      will make this block_rsv's reserved bytes keep growing, and this reserved
      space will only be released in the end of btrfs_truncate(), this metadata
      leak will impact other's metadata reservation. In this case, it's
      "btrfs_start_transaction(root, 2);" fails for enospc error, which make
      this truncate operation fail.
      
      Call btrfs_block_rsv_release() to fix this bug.
      Signed-off-by: default avatarWang Xiaoguang <wangxg.fnst@cn.fujitsu.com>
      Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
      Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
      47b5d646
  2. 11 Jan, 2017 1 commit
  3. 09 Jan, 2017 4 commits
  4. 04 Jan, 2017 1 commit
  5. 03 Jan, 2017 5 commits
  6. 19 Dec, 2016 1 commit
  7. 13 Dec, 2016 2 commits
    • Maxim Patlasov's avatar
      btrfs: limit async_work allocation and worker func duration · 2939e1a8
      Maxim Patlasov authored
      Problem statement: unprivileged user who has read-write access to more than
      one btrfs subvolume may easily consume all kernel memory (eventually
      triggering oom-killer).
      
      Reproducer (./mkrmdir below essentially loops over mkdir/rmdir):
      
      [root@kteam1 ~]# cat prep.sh
      
      DEV=/dev/sdb
      mkfs.btrfs -f $DEV
      mount $DEV /mnt
      for i in `seq 1 16`
      do
      	mkdir /mnt/$i
      	btrfs subvolume create /mnt/SV_$i
      	ID=`btrfs subvolume list /mnt |grep "SV_$i$" |cut -d ' ' -f 2`
      	mount -t btrfs -o subvolid=$ID $DEV /mnt/$i
      	chmod a+rwx /mnt/$i
      done
      
      [root@kteam1 ~]# sh prep.sh
      
      [maxim@kteam1 ~]$ for i in `seq 1 16`; do ./mkrmdir /mnt/$i 2000 2000 & done
      
      [root@kteam1 ~]# for i in `seq 1 4`; do grep "kmalloc-128" /proc/slabinfo | grep -v dma; sleep 60; done
      kmalloc-128        10144  10144    128   32    1 : tunables    0    0    0 : slabdata    317    317      0
      kmalloc-128       9992352 9992352    128   32    1 : tunables    0    0    0 : slabdata 312261 312261      0
      kmalloc-128       24226752 24226752    128   32    1 : tunables    0    0    0 : slabdata 757086 757086      0
      kmalloc-128       42754240 42754240    128   32    1 : tunables    0    0    0 : slabdata 1336070 1336070      0
      
      The huge numbers above come from insane number of async_work-s allocated
      and queued by btrfs_wq_run_delayed_node.
      
      The problem is caused by btrfs_wq_run_delayed_node() queuing more and more
      works if the number of delayed items is above BTRFS_DELAYED_BACKGROUND. The
      worker func (btrfs_async_run_delayed_root) processes at least
      BTRFS_DELAYED_BATCH items (if they are present in the list). So, the machinery
      works as expected while the list is almost empty. As soon as it is getting
      bigger, worker func starts to process more than one item at a time, it takes
      longer, and the chances to have async_works queued more than needed is getting
      higher.
      
      The problem above is worsened by another flaw of delayed-inode implementation:
      if async_work was queued in a throttling branch (number of items >=
      BTRFS_DELAYED_WRITEBACK), corresponding worker func won't quit until
      the number of items < BTRFS_DELAYED_BACKGROUND / 2. So, it is possible that
      the func occupies CPU infinitely (up to 30sec in my experiments): while the
      func is trying to drain the list, the user activity may add more and more
      items to the list.
      
      The patch fixes both problems in straightforward way: refuse queuing too
      many works in btrfs_wq_run_delayed_node and bail out of worker func if
      at least BTRFS_DELAYED_WRITEBACK items are processed.
      
      Changed in v2: remove support of thresh == NO_THRESHOLD.
      Signed-off-by: default avatarMaxim Patlasov <mpatlasov@virtuozzo.com>
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      Cc: stable@vger.kernel.org # v3.15+
      2939e1a8
    • Chris Mason's avatar
      Merge branch 'for-chris-4.10' of... · 5f52a2c5
      Chris Mason authored
      Merge branch 'for-chris-4.10' of git://git.kernel.org/pub/scm/linux/kernel/git/fdmanana/linux into for-linus-4.10
      
      Patches queued up by Filipe:
      
      The most important change is still the fix for the extent tree
      corruption that happens due to balance when qgroups are enabled (a
      regression introduced in 4.7 by a fix for a regression from the last
      qgroups rework). This has been hitting SLE and openSUSE users and QA
      very badly, where transactions keep getting aborted when running
      delayed references leaving the root filesystem in RO mode and nearly
      unusable.  There are fixes here that allow us to run xfstests again
      with the integrity checker enabled, which has been impossible since 4.8
      (apparently I'm the only one running xfstests with the integrity
      checker enabled, which is useful to validate dirtied leafs, like
      checking if there are keys out of order, etc).  The rest are just some
      trivial fixes, most of them tagged for stable, and two cleanups.
      Signed-off-by: default avatarChris Mason <clm@fb.com>
      5f52a2c5
  8. 11 Dec, 2016 1 commit
  9. 09 Dec, 2016 1 commit
  10. 06 Dec, 2016 20 commits
  11. 30 Nov, 2016 2 commits
    • Robbie Ko's avatar
      Btrfs: fix tree search logic when replaying directory entry deletes · 2a7bf53f
      Robbie Ko authored
      If a log tree has a layout like the following:
      
      leaf N:
              ...
              item 240 key (282 DIR_LOG_ITEM 0) itemoff 8189 itemsize 8
                      dir log end 1275809046
      leaf N + 1:
              item 0 key (282 DIR_LOG_ITEM 3936149215) itemoff 16275 itemsize 8
                      dir log end 18446744073709551615
              ...
      
      When we pass the value 1275809046 + 1 as the parameter start_ret to the
      function tree-log.c:find_dir_range() (done by replay_dir_deletes()), we
      end up with path->slots[0] having the value 239 (points to the last item
      of leaf N, item 240). Because the dir log item in that position has an
      offset value smaller than *start_ret (1275809046 + 1) we need to move on
      to the next leaf, however the logic for that is wrong since it compares
      the current slot to the number of items in the leaf, which is smaller
      and therefore we don't lookup for the next leaf but instead we set the
      slot to point to an item that does not exist, at slot 240, and we later
      operate on that slot which has unexpected content or in the worst case
      can result in an invalid memory access (accessing beyond the last page
      of leaf N's extent buffer).
      
      So fix the logic that checks when we need to lookup at the next leaf
      by first incrementing the slot and only after to check if that slot
      is beyond the last item of the current leaf.
      Signed-off-by: default avatarRobbie Ko <robbieko@synology.com>
      Reviewed-by: default avatarFilipe Manana <fdmanana@suse.com>
      Fixes: e02119d5 (Btrfs: Add a write ahead tree log to optimize synchronous operations)
      Cc: stable@vger.kernel.org  # 2.6.29+
      Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
      [Modified changelog for clarity and correctness]
      2a7bf53f
    • Robbie Ko's avatar
      Btrfs: fix deadlock caused by fsync when logging directory entries · ec125cfb
      Robbie Ko authored
      While logging new directory entries, at tree-log.c:log_new_dir_dentries(),
      after we call btrfs_search_forward() we get a leaf with a read lock on it,
      and without unlocking that leaf we can end up calling btrfs_iget() to get
      an inode pointer. The later (btrfs_iget()) can end up doing a read-only
      search on the same tree again, if the inode is not in memory already, which
      ends up causing a deadlock if some other task in the meanwhile started a
      write search on the tree and is attempting to write lock the same leaf
      that btrfs_search_forward() locked while holding write locks on upper
      levels of the tree blocking the read search from btrfs_iget(). In this
      scenario we get a deadlock.
      
      So fix this by releasing the search path before calling btrfs_iget() at
      tree-log.c:log_new_dir_dentries().
      
      Example trace of such deadlock:
      
      [ 4077.478852] kworker/u24:10  D ffff88107fc90640     0 14431      2 0x00000000
      [ 4077.486752] Workqueue: btrfs-endio-write btrfs_endio_write_helper [btrfs]
      [ 4077.494346]  ffff880ffa56bad0 0000000000000046 0000000000009000 ffff880ffa56bfd8
      [ 4077.502629]  ffff880ffa56bfd8 ffff881016ce21c0 ffffffffa06ecb26 ffff88101a5d6138
      [ 4077.510915]  ffff880ebb5173b0 ffff880ffa56baf8 ffff880ebb517410 ffff881016ce21c0
      [ 4077.519202] Call Trace:
      [ 4077.528752]  [<ffffffffa06ed5ed>] ? btrfs_tree_lock+0xdd/0x2f0 [btrfs]
      [ 4077.536049]  [<ffffffff81053680>] ? wake_up_atomic_t+0x30/0x30
      [ 4077.542574]  [<ffffffffa068cc1f>] ? btrfs_search_slot+0x79f/0xb10 [btrfs]
      [ 4077.550171]  [<ffffffffa06a5073>] ? btrfs_lookup_file_extent+0x33/0x40 [btrfs]
      [ 4077.558252]  [<ffffffffa06c600b>] ? __btrfs_drop_extents+0x13b/0xdf0 [btrfs]
      [ 4077.566140]  [<ffffffffa06fc9e2>] ? add_delayed_data_ref+0xe2/0x150 [btrfs]
      [ 4077.573928]  [<ffffffffa06fd629>] ? btrfs_add_delayed_data_ref+0x149/0x1d0 [btrfs]
      [ 4077.582399]  [<ffffffffa06cf3c0>] ? __set_extent_bit+0x4c0/0x5c0 [btrfs]
      [ 4077.589896]  [<ffffffffa06b4a64>] ? insert_reserved_file_extent.constprop.75+0xa4/0x320 [btrfs]
      [ 4077.599632]  [<ffffffffa06b206d>] ? start_transaction+0x8d/0x470 [btrfs]
      [ 4077.607134]  [<ffffffffa06bab57>] ? btrfs_finish_ordered_io+0x2e7/0x600 [btrfs]
      [ 4077.615329]  [<ffffffff8104cbc2>] ? process_one_work+0x142/0x3d0
      [ 4077.622043]  [<ffffffff8104d729>] ? worker_thread+0x109/0x3b0
      [ 4077.628459]  [<ffffffff8104d620>] ? manage_workers.isra.26+0x270/0x270
      [ 4077.635759]  [<ffffffff81052b0f>] ? kthread+0xaf/0xc0
      [ 4077.641404]  [<ffffffff81052a60>] ? kthread_create_on_node+0x110/0x110
      [ 4077.648696]  [<ffffffff814a9ac8>] ? ret_from_fork+0x58/0x90
      [ 4077.654926]  [<ffffffff81052a60>] ? kthread_create_on_node+0x110/0x110
      
      [ 4078.358087] kworker/u24:15  D ffff88107fcd0640     0 14436      2 0x00000000
      [ 4078.365981] Workqueue: btrfs-endio-write btrfs_endio_write_helper [btrfs]
      [ 4078.373574]  ffff880ffa57fad0 0000000000000046 0000000000009000 ffff880ffa57ffd8
      [ 4078.381864]  ffff880ffa57ffd8 ffff88103004d0a0 ffffffffa06ecb26 ffff88101a5d6138
      [ 4078.390163]  ffff880fbeffc298 ffff880ffa57faf8 ffff880fbeffc2f8 ffff88103004d0a0
      [ 4078.398466] Call Trace:
      [ 4078.408019]  [<ffffffffa06ed5ed>] ? btrfs_tree_lock+0xdd/0x2f0 [btrfs]
      [ 4078.415322]  [<ffffffff81053680>] ? wake_up_atomic_t+0x30/0x30
      [ 4078.421844]  [<ffffffffa068cc1f>] ? btrfs_search_slot+0x79f/0xb10 [btrfs]
      [ 4078.429438]  [<ffffffffa06a5073>] ? btrfs_lookup_file_extent+0x33/0x40 [btrfs]
      [ 4078.437518]  [<ffffffffa06c600b>] ? __btrfs_drop_extents+0x13b/0xdf0 [btrfs]
      [ 4078.445404]  [<ffffffffa06fc9e2>] ? add_delayed_data_ref+0xe2/0x150 [btrfs]
      [ 4078.453194]  [<ffffffffa06fd629>] ? btrfs_add_delayed_data_ref+0x149/0x1d0 [btrfs]
      [ 4078.461663]  [<ffffffffa06cf3c0>] ? __set_extent_bit+0x4c0/0x5c0 [btrfs]
      [ 4078.469161]  [<ffffffffa06b4a64>] ? insert_reserved_file_extent.constprop.75+0xa4/0x320 [btrfs]
      [ 4078.478893]  [<ffffffffa06b206d>] ? start_transaction+0x8d/0x470 [btrfs]
      [ 4078.486388]  [<ffffffffa06bab57>] ? btrfs_finish_ordered_io+0x2e7/0x600 [btrfs]
      [ 4078.494561]  [<ffffffff8104cbc2>] ? process_one_work+0x142/0x3d0
      [ 4078.501278]  [<ffffffff8104a507>] ? pwq_activate_delayed_work+0x27/0x40
      [ 4078.508673]  [<ffffffff8104d729>] ? worker_thread+0x109/0x3b0
      [ 4078.515098]  [<ffffffff8104d620>] ? manage_workers.isra.26+0x270/0x270
      [ 4078.522396]  [<ffffffff81052b0f>] ? kthread+0xaf/0xc0
      [ 4078.528032]  [<ffffffff81052a60>] ? kthread_create_on_node+0x110/0x110
      [ 4078.535325]  [<ffffffff814a9ac8>] ? ret_from_fork+0x58/0x90
      [ 4078.541552]  [<ffffffff81052a60>] ? kthread_create_on_node+0x110/0x110
      
      [ 4079.355824] user-space-program D ffff88107fd30640     0 32020      1 0x00000000
      [ 4079.363716]  ffff880eae8eba10 0000000000000086 0000000000009000 ffff880eae8ebfd8
      [ 4079.372003]  ffff880eae8ebfd8 ffff881016c162c0 ffffffffa06ecb26 ffff88101a5d6138
      [ 4079.380294]  ffff880fbed4b4c8 ffff880eae8eba38 ffff880fbed4b528 ffff881016c162c0
      [ 4079.388586] Call Trace:
      [ 4079.398134]  [<ffffffffa06ed595>] ? btrfs_tree_lock+0x85/0x2f0 [btrfs]
      [ 4079.405431]  [<ffffffff81053680>] ? wake_up_atomic_t+0x30/0x30
      [ 4079.411955]  [<ffffffffa06876fb>] ? btrfs_lock_root_node+0x2b/0x40 [btrfs]
      [ 4079.419644]  [<ffffffffa068ce83>] ? btrfs_search_slot+0xa03/0xb10 [btrfs]
      [ 4079.427237]  [<ffffffffa06aba52>] ? btrfs_buffer_uptodate+0x52/0x70 [btrfs]
      [ 4079.435041]  [<ffffffffa0689b60>] ? generic_bin_search.constprop.38+0x80/0x190 [btrfs]
      [ 4079.443897]  [<ffffffffa068ea44>] ? btrfs_insert_empty_items+0x74/0xd0 [btrfs]
      [ 4079.451975]  [<ffffffffa072c443>] ? copy_items+0x128/0x850 [btrfs]
      [ 4079.458890]  [<ffffffffa072da10>] ? btrfs_log_inode+0x629/0xbf3 [btrfs]
      [ 4079.466292]  [<ffffffffa06f34a1>] ? btrfs_log_inode_parent+0xc61/0xf30 [btrfs]
      [ 4079.474373]  [<ffffffffa06f45a9>] ? btrfs_log_dentry_safe+0x59/0x80 [btrfs]
      [ 4079.482161]  [<ffffffffa06c298d>] ? btrfs_sync_file+0x20d/0x330 [btrfs]
      [ 4079.489558]  [<ffffffff8112777c>] ? do_fsync+0x4c/0x80
      [ 4079.495300]  [<ffffffff81127a0a>] ? SyS_fdatasync+0xa/0x10
      [ 4079.501422]  [<ffffffff814a9b72>] ? system_call_fastpath+0x16/0x1b
      
      [ 4079.508334] user-space-program D ffff88107fc30640     0 32021      1 0x00000004
      [ 4079.516226]  ffff880eae8efbf8 0000000000000086 0000000000009000 ffff880eae8effd8
      [ 4079.524513]  ffff880eae8effd8 ffff881030279610 ffffffffa06ecb26 ffff88101a5d6138
      [ 4079.532802]  ffff880ebb671d88 ffff880eae8efc20 ffff880ebb671de8 ffff881030279610
      [ 4079.541092] Call Trace:
      [ 4079.550642]  [<ffffffffa06ed595>] ? btrfs_tree_lock+0x85/0x2f0 [btrfs]
      [ 4079.557941]  [<ffffffff81053680>] ? wake_up_atomic_t+0x30/0x30
      [ 4079.564463]  [<ffffffffa068cc1f>] ? btrfs_search_slot+0x79f/0xb10 [btrfs]
      [ 4079.572058]  [<ffffffffa06bb7d8>] ? btrfs_truncate_inode_items+0x168/0xb90 [btrfs]
      [ 4079.580526]  [<ffffffffa06b04be>] ? join_transaction.isra.15+0x1e/0x3a0 [btrfs]
      [ 4079.588701]  [<ffffffffa06b206d>] ? start_transaction+0x8d/0x470 [btrfs]
      [ 4079.596196]  [<ffffffffa0690ac6>] ? block_rsv_add_bytes+0x16/0x50 [btrfs]
      [ 4079.603789]  [<ffffffffa06bc2e9>] ? btrfs_truncate+0xe9/0x2e0 [btrfs]
      [ 4079.610994]  [<ffffffffa06bd00b>] ? btrfs_setattr+0x30b/0x410 [btrfs]
      [ 4079.618197]  [<ffffffff81117c1c>] ? notify_change+0x1dc/0x680
      [ 4079.624625]  [<ffffffff8123c8a4>] ? aa_path_perm+0xd4/0x160
      [ 4079.630854]  [<ffffffff810f4fcb>] ? do_truncate+0x5b/0x90
      [ 4079.636889]  [<ffffffff810f59fa>] ? do_sys_ftruncate.constprop.15+0x10a/0x160
      [ 4079.644869]  [<ffffffff8110d87b>] ? SyS_fcntl+0x5b/0x570
      [ 4079.650805]  [<ffffffff814a9b72>] ? system_call_fastpath+0x16/0x1b
      
      [ 4080.410607] user-space-program D ffff88107fc70640     0 32028  12639 0x00000004
      [ 4080.418489]  ffff880eaeccbbe0 0000000000000086 0000000000009000 ffff880eaeccbfd8
      [ 4080.426778]  ffff880eaeccbfd8 ffff880f317ef1e0 ffffffffa06ecb26 ffff88101a5d6138
      [ 4080.435067]  ffff880ef7e93928 ffff880f317ef1e0 ffff880eaeccbc08 ffff880f317ef1e0
      [ 4080.443353] Call Trace:
      [ 4080.452920]  [<ffffffffa06ed15d>] ? btrfs_tree_read_lock+0xdd/0x190 [btrfs]
      [ 4080.460703]  [<ffffffff81053680>] ? wake_up_atomic_t+0x30/0x30
      [ 4080.467225]  [<ffffffffa06876bb>] ? btrfs_read_lock_root_node+0x2b/0x40 [btrfs]
      [ 4080.475400]  [<ffffffffa068cc81>] ? btrfs_search_slot+0x801/0xb10 [btrfs]
      [ 4080.482994]  [<ffffffffa06b2df0>] ? btrfs_clean_one_deleted_snapshot+0xe0/0xe0 [btrfs]
      [ 4080.491857]  [<ffffffffa06a70a6>] ? btrfs_lookup_inode+0x26/0x90 [btrfs]
      [ 4080.499353]  [<ffffffff810ec42f>] ? kmem_cache_alloc+0xaf/0xc0
      [ 4080.505879]  [<ffffffffa06bd905>] ? btrfs_iget+0xd5/0x5d0 [btrfs]
      [ 4080.512696]  [<ffffffffa06caf04>] ? btrfs_get_token_64+0x104/0x120 [btrfs]
      [ 4080.520387]  [<ffffffffa06f341f>] ? btrfs_log_inode_parent+0xbdf/0xf30 [btrfs]
      [ 4080.528469]  [<ffffffffa06f45a9>] ? btrfs_log_dentry_safe+0x59/0x80 [btrfs]
      [ 4080.536258]  [<ffffffffa06c298d>] ? btrfs_sync_file+0x20d/0x330 [btrfs]
      [ 4080.543657]  [<ffffffff8112777c>] ? do_fsync+0x4c/0x80
      [ 4080.549399]  [<ffffffff81127a0a>] ? SyS_fdatasync+0xa/0x10
      [ 4080.555534]  [<ffffffff814a9b72>] ? system_call_fastpath+0x16/0x1b
      Signed-off-by: default avatarRobbie Ko <robbieko@synology.com>
      Reviewed-by: default avatarFilipe Manana <fdmanana@suse.com>
      Fixes: 2f2ff0ee (Btrfs: fix metadata inconsistencies after directory fsync)
      Cc: stable@vger.kernel.org # 4.1+
      Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
      [Modified changelog for clarity and correctness]
      ec125cfb