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  1. 06 Aug, 2015 7 commits
    • Michal Hocko's avatar
      ext4: replace open coded nofail allocation in ext4_free_blocks() · 61bd00c1
      Michal Hocko authored 
      commit 7444a072 upstream.

ext4_free_blocks is looping around the allocation request and mimics
__GFP_NOFAIL behavior without any allocation fallback strategy. Let's
remove the open coded loop and replace it with __GFP_NOFAIL. Without the
flag the allocator has no way to find out never-fail requirement and
cannot help in any way.
Signed-off-by: default avatarMichal Hocko <mhocko@suse.cz>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
      61bd00c1
    • Eryu Guan's avatar
      ext4: correctly migrate a file with a hole at the beginning · 4e792b2a
      Eryu Guan authored 
      commit 8974fec7 upstream.

Currently ext4_ind_migrate() doesn't correctly handle a file which
contains a hole at the beginning of the file.  This caused the migration
to be done incorrectly, and then if there is a subsequent following
delayed allocation write to the "hole", this would reclaim the same data
blocks again and results in fs corruption.

  # assmuing 4k block size ext4, with delalloc enabled
  # skip the first block and write to the second block
  xfs_io -fc "pwrite 4k 4k" -c "fsync" /mnt/ext4/testfile

  # converting to indirect-mapped file, which would move the data blocks
  # to the beginning of the file, but extent status cache still marks
  # that region as a hole
  chattr -e /mnt/ext4/testfile

  # delayed allocation writes to the "hole", reclaim the same data block
  # again, results in i_blocks corruption
  xfs_io -c "pwrite 0 4k" /mnt/ext4/testfile
  umount /mnt/ext4
  e2fsck -nf /dev/sda6
  ...
  Inode 53, i_blocks is 16, should be 8.  Fix? no
  ...
Signed-off-by: default avatarEryu Guan <guaneryu@gmail.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
      4e792b2a
    • Eryu Guan's avatar
      ext4: be more strict when migrating to non-extent based file · 261c583a
      Eryu Guan authored 
      commit d6f123a9 upstream.

Currently the check in ext4_ind_migrate() is not enough before doing the
real conversion:

a) delayed allocated extents could bypass the check on eh->eh_entries
   and eh->eh_depth

This can be demonstrated by this script

  xfs_io -fc "pwrite 0 4k" -c "pwrite 8k 4k" /mnt/ext4/testfile
  chattr -e /mnt/ext4/testfile

where testfile has two extents but still be converted to non-extent
based file format.

b) only extent length is checked but not the offset, which would result
   in data lose (delalloc) or fs corruption (nodelalloc), because
   non-extent based file only supports at most (12 + 2^10 + 2^20 + 2^30)
   blocks

This can be demostrated by

  xfs_io -fc "pwrite 5T 4k" /mnt/ext4/testfile
  chattr -e /mnt/ext4/testfile
  sync

If delalloc is enabled, dmesg prints
  EXT4-fs warning (device dm-4): ext4_block_to_path:105: block 1342177280 > max in inode 53
  EXT4-fs (dm-4): Delayed block allocation failed for inode 53 at logical offset 1342177280 with max blocks 1 with error 5
  EXT4-fs (dm-4): This should not happen!! Data will be lost

If delalloc is disabled, e2fsck -nf shows corruption
  Inode 53, i_size is 5497558142976, should be 4096.  Fix? no

Fix the two issues by

a) forcing all delayed allocation blocks to be allocated before checking
   eh->eh_depth and eh->eh_entries
b) limiting the last logical block of the extent is within direct map
Signed-off-by: default avatarEryu Guan <guaneryu@gmail.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
      261c583a
    • Lukas Czerner's avatar
      ext4: fix reservation release on invalidatepage for delalloc fs · e726980a
      Lukas Czerner authored 
      commit 9705acd6 upstream.

On delalloc enabled file system on invalidatepage operation
in ext4_da_page_release_reservation() we want to clear the delayed
buffer and remove the extent covering the delayed buffer from the extent
status tree.

However currently there is a bug where on the systems with page size >
block size we will always remove extents from the start of the page
regardless where the actual delayed buffers are positioned in the page.
This leads to the errors like this:

EXT4-fs warning (device loop0): ext4_da_release_space:1225:
ext4_da_release_space: ino 13, to_free 1 with only 0 reserved data
blocks

This however can cause data loss on writeback time if the file system is
in ENOSPC condition because we're releasing reservation for someones
else delayed buffer.

Fix this by only removing extents that corresponds to the part of the
page we want to invalidate.

This problem is reproducible by the following fio receipt (however I was
only able to reproduce it with fio-2.1 or older.

[global]
bs=8k
iodepth=1024
iodepth_batch=60
randrepeat=1
size=1m
directory=/mnt/test
numjobs=20
[job1]
ioengine=sync
bs=1k
direct=1
rw=randread
filename=file1:file2
[job2]
ioengine=libaio
rw=randwrite
direct=1
filename=file1:file2
[job3]
bs=1k
ioengine=posixaio
rw=randwrite
direct=1
filename=file1:file2
[job5]
bs=1k
ioengine=sync
rw=randread
filename=file1:file2
[job7]
ioengine=libaio
rw=randwrite
filename=file1:file2
[job8]
ioengine=posixaio
rw=randwrite
filename=file1:file2
[job10]
ioengine=mmap
rw=randwrite
bs=1k
filename=file1:file2
[job11]
ioengine=mmap
rw=randwrite
direct=1
filename=file1:file2
Signed-off-by: default avatarLukas Czerner <lczerner@redhat.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
      e726980a
    • Filipe Manana's avatar
      Btrfs: fix fsync data loss after append write · f5880941
      Filipe Manana authored 
      commit e4545de5 upstream.

If we do an append write to a file (which increases its inode's i_size)
that does not have the flag BTRFS_INODE_NEEDS_FULL_SYNC set in its inode,
and the previous transaction added a new hard link to the file, which sets
the flag BTRFS_INODE_COPY_EVERYTHING in the file's inode, and then fsync
the file, the inode's new i_size isn't logged. This has the consequence
that after the fsync log is replayed, the file size remains what it was
before the append write operation, which means users/applications will
not be able to read the data that was successsfully fsync'ed before.

This happens because neither the inode item nor the delayed inode get
their i_size updated when the append write is made - doing so would
require starting a transaction in the buffered write path, something that
we do not do intentionally for performance reasons.

Fix this by making sure that when the flag BTRFS_INODE_COPY_EVERYTHING is
set the inode is logged with its current i_size (log the in-memory inode
into the log tree).

This issue is not a recent regression and is easy to reproduce with the
following test case for fstests:

  seq=`basename $0`
  seqres=$RESULT_DIR/$seq
  echo "QA output created by $seq"

  here=`pwd`
  tmp=/tmp/$$
  status=1	# failure is the default!

  _cleanup()
  {
          _cleanup_flakey
          rm -f $tmp.*
  }
  trap "_cleanup; exit \$status" 0 1 2 3 15

  # get standard environment, filters and checks
  . ./common/rc
  . ./common/filter
  . ./common/dmflakey

  # real QA test starts here
  _supported_fs generic
  _supported_os Linux
  _need_to_be_root
  _require_scratch
  _require_dm_flakey
  _require_metadata_journaling $SCRATCH_DEV

  _crash_and_mount()
  {
          # Simulate a crash/power loss.
          _load_flakey_table $FLAKEY_DROP_WRITES
          _unmount_flakey
          # Allow writes again and mount. This makes the fs replay its fsync log.
          _load_flakey_table $FLAKEY_ALLOW_WRITES
          _mount_flakey
  }

  rm -f $seqres.full

  _scratch_mkfs >> $seqres.full 2>&1
  _init_flakey
  _mount_flakey

  # Create the test file with some initial data and then fsync it.
  # The fsync here is only needed to trigger the issue in btrfs, as it causes the
  # the flag BTRFS_INODE_NEEDS_FULL_SYNC to be removed from the btrfs inode.
  $XFS_IO_PROG -f -c "pwrite -S 0xaa 0 32k" \
                  -c "fsync" \
                  $SCRATCH_MNT/foo | _filter_xfs_io
  sync

  # Add a hard link to our file.
  # On btrfs this sets the flag BTRFS_INODE_COPY_EVERYTHING on the btrfs inode,
  # which is a necessary condition to trigger the issue.
  ln $SCRATCH_MNT/foo $SCRATCH_MNT/bar

  # Sync the filesystem to force a commit of the current btrfs transaction, this
  # is a necessary condition to trigger the bug on btrfs.
  sync

  # Now append more data to our file, increasing its size, and fsync the file.
  # In btrfs because the inode flag BTRFS_INODE_COPY_EVERYTHING was set and the
  # write path did not update the inode item in the btree nor the delayed inode
  # item (in memory struture) in the current transaction (created by the fsync
  # handler), the fsync did not record the inode's new i_size in the fsync
  # log/journal. This made the data unavailable after the fsync log/journal is
  # replayed.
  $XFS_IO_PROG -c "pwrite -S 0xbb 32K 32K" \
               -c "fsync" \
               $SCRATCH_MNT/foo | _filter_xfs_io

  echo "File content after fsync and before crash:"
  od -t x1 $SCRATCH_MNT/foo

  _crash_and_mount

  echo "File content after crash and log replay:"
  od -t x1 $SCRATCH_MNT/foo

  status=0
  exit

The expected file output before and after the crash/power failure expects the
appended data to be available, which is:

  0000000 aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa
  *
  0100000 bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb
  *
  0200000
Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Reviewed-by: default avatarLiu Bo <bo.li.liu@oracle.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
      f5880941
    • Filipe Manana's avatar
      Btrfs: fix race between caching kthread and returning inode to inode cache · 13321418
      Filipe Manana authored 
      commit ae9d8f17 upstream.

While the inode cache caching kthread is calling btrfs_unpin_free_ino(),
we could have a concurrent call to btrfs_return_ino() that adds a new
entry to the root's free space cache of pinned inodes. This concurrent
call does not acquire the fs_info->commit_root_sem before adding a new
entry if the caching state is BTRFS_CACHE_FINISHED, which is a problem
because the caching kthread calls btrfs_unpin_free_ino() after setting
the caching state to BTRFS_CACHE_FINISHED and therefore races with
the task calling btrfs_return_ino(), which is adding a new entry, while
the former (caching kthread) is navigating the cache's rbtree, removing
and freeing nodes from the cache's rbtree without acquiring the spinlock
that protects the rbtree.

This race resulted in memory corruption due to double free of struct
btrfs_free_space objects because both tasks can end up doing freeing the
same objects. Note that adding a new entry can result in merging it with
other entries in the cache, in which case those entries are freed.
This is particularly important as btrfs_free_space structures are also
used for the block group free space caches.

This memory corruption can be detected by a debugging kernel, which
reports it with the following trace:

[132408.501148] slab error in verify_redzone_free(): cache `btrfs_free_space': double free detected
[132408.505075] CPU: 15 PID: 12248 Comm: btrfs-ino-cache Tainted: G        W       4.1.0-rc5-btrfs-next-10+ #1
[132408.505075] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.8.1-0-g4adadbd-20150316_085822-nilsson.home.kraxel.org 04/01/2014
[132408.505075]  ffff880023e7d320 ffff880163d73cd8 ffffffff8145eec7 ffffffff81095dce
[132408.505075]  ffff880009735d40 ffff880163d73ce8 ffffffff81154e1e ffff880163d73d68
[132408.505075]  ffffffff81155733 ffffffffa054a95a ffff8801b6099f00 ffffffffa0505b5f
[132408.505075] Call Trace:
[132408.505075]  [<ffffffff8145eec7>] dump_stack+0x4f/0x7b
[132408.505075]  [<ffffffff81095dce>] ? console_unlock+0x356/0x3a2
[132408.505075]  [<ffffffff81154e1e>] __slab_error.isra.28+0x25/0x36
[132408.505075]  [<ffffffff81155733>] __cache_free+0xe2/0x4b6
[132408.505075]  [<ffffffffa054a95a>] ? __btrfs_add_free_space+0x2f0/0x343 [btrfs]
[132408.505075]  [<ffffffffa0505b5f>] ? btrfs_unpin_free_ino+0x8e/0x99 [btrfs]
[132408.505075]  [<ffffffff810f3b30>] ? time_hardirqs_off+0x15/0x28
[132408.505075]  [<ffffffff81084d42>] ? trace_hardirqs_off+0xd/0xf
[132408.505075]  [<ffffffff811563a1>] ? kfree+0xb6/0x14e
[132408.505075]  [<ffffffff811563d0>] kfree+0xe5/0x14e
[132408.505075]  [<ffffffffa0505b5f>] btrfs_unpin_free_ino+0x8e/0x99 [btrfs]
[132408.505075]  [<ffffffffa0505e08>] caching_kthread+0x29e/0x2d9 [btrfs]
[132408.505075]  [<ffffffffa0505b6a>] ? btrfs_unpin_free_ino+0x99/0x99 [btrfs]
[132408.505075]  [<ffffffff8106698f>] kthread+0xef/0xf7
[132408.505075]  [<ffffffff810f3b08>] ? time_hardirqs_on+0x15/0x28
[132408.505075]  [<ffffffff810668a0>] ? __kthread_parkme+0xad/0xad
[132408.505075]  [<ffffffff814653d2>] ret_from_fork+0x42/0x70
[132408.505075]  [<ffffffff810668a0>] ? __kthread_parkme+0xad/0xad
[132408.505075] ffff880023e7d320: redzone 1:0x9f911029d74e35b, redzone 2:0x9f911029d74e35b.
[132409.501654] slab: double free detected in cache 'btrfs_free_space', objp ffff880023e7d320
[132409.503355] ------------[ cut here ]------------
[132409.504241] kernel BUG at mm/slab.c:2571!

Therefore fix this by having btrfs_unpin_free_ino() acquire the lock
that protects the rbtree while doing the searches and removing entries.

Fixes: 1c70d8fb ("Btrfs: fix inode caching vs tree log")
Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: default avatarLuis Henriques <luis.henriques@canonical.com>
Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
      13321418
    • Filipe Manana's avatar
      Btrfs: use kmem_cache_free when freeing entry in inode cache · 6c7f16ec
      Filipe Manana authored 
      commit c3f4a168 upstream.

The free space entries are allocated using kmem_cache_zalloc(),
through __btrfs_add_free_space(), therefore we should use
kmem_cache_free() and not kfree() to avoid any confusion and
any potential problem. Looking at the kfree() definition at
mm/slab.c it has the following comment:

  /*
   * (...)
   *
   * Don't free memory not originally allocated by kmalloc()
   * or you will run into trouble.
   */

So better be safe and use kmem_cache_free().
Signed-off-by: default avatarFilipe Manana <fdmanana@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.cz>
Signed-off-by: default avatarChris Mason <clm@fb.com>
Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
      6c7f16ec
  3. 04 Aug, 2015 1 commit
  5. 30 Jul, 2015 9 commits
  7. 28 Jul, 2015 1 commit
  9. 23 Jul, 2015 22 commits
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