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  1. 26 Jan, 2017 3 commits
  3. 19 Jan, 2017 3 commits
    • Liu Bo's avatar
      Btrfs: fix truncate down when no_holes feature is enabled · 91298eec
      Liu Bo authored 
      For such a file mapping,

[0-4k][hole][8k-12k]

In NO_HOLES mode, we don't have the [hole] extent any more.
Commit c1aa4575 ("Btrfs: fix shrinking truncate when the no_holes feature is enabled")
 fixed disk isize not being updated in NO_HOLES mode when data is not flushed.

However, even if data has been flushed, we can still have trouble
in updating disk isize since we updated disk isize to 'start' of
the last evicted extent.
Reviewed-by: default avatarChris Mason <clm@fb.com>
Signed-off-by: default avatarLiu Bo <bo.li.liu@oracle.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
      91298eec
    • 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
  5. 11 Jan, 2017 1 commit
  7. 09 Jan, 2017 4 commits
  9. 04 Jan, 2017 1 commit
  11. 03 Jan, 2017 5 commits
  13. 19 Dec, 2016 1 commit
  15. 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
  17. 11 Dec, 2016 1 commit
  19. 09 Dec, 2016 1 commit
  21. 06 Dec, 2016 18 commits
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