linux-toradex.git/fs/btrfs, branch v3.2.73 Linux kernel for Apalis and Colibri modules btrfs: skip waiting on ordered range for special files 2015-10-13T02:46:09+00:00 Jeff Mahoney jeffm@suse.com 2015-09-12T01:44:17+00:00 6910b17342022468f9793c70d57a835d44187bd7 commit a30e577c96f59b1e1678ea5462432b09bf7d5cbc upstream. In btrfs_evict_inode, we properly truncate the page cache for evicted inodes but then we call btrfs_wait_ordered_range for every inode as well. It's the right thing to do for regular files but results in incorrect behavior for device inodes for block devices. filemap_fdatawrite_range gets called with inode->i_mapping which gets resolved to the block device inode before getting passed to wbc_attach_fdatawrite_inode and ultimately to inode_to_bdi. What happens next depends on whether there's an open file handle associated with the inode. If there is, we write to the block device, which is unexpected behavior. If there isn't, we through normally and inode->i_data is used. We can also end up racing against open/close which can result in crashes when i_mapping points to a block device inode that has been closed. Since there can't be any page cache associated with special file inodes, it's safe to skip the btrfs_wait_ordered_range call entirely and avoid the problem. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=100911 Tested-by: Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de> Signed-off-by: Jeff Mahoney <jeffm@suse.com> Reviewed-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit a30e577c96f59b1e1678ea5462432b09bf7d5cbc upstream.

In btrfs_evict_inode, we properly truncate the page cache for evicted
inodes but then we call btrfs_wait_ordered_range for every inode as well.
It's the right thing to do for regular files but results in incorrect
behavior for device inodes for block devices.

filemap_fdatawrite_range gets called with inode->i_mapping which gets
resolved to the block device inode before getting passed to
wbc_attach_fdatawrite_inode and ultimately to inode_to_bdi.  What happens
next depends on whether there's an open file handle associated with the
inode.  If there is, we write to the block device, which is unexpected
behavior.  If there isn't, we through normally and inode->i_data is used.
We can also end up racing against open/close which can result in crashes
when i_mapping points to a block device inode that has been closed.

Since there can't be any page cache associated with special file inodes,
it's safe to skip the btrfs_wait_ordered_range call entirely and avoid
the problem.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=100911
Tested-by: Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de>
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Btrfs: fix read corruption of compressed and shared extents 2015-10-13T02:46:09+00:00 Filipe Manana fdmanana@suse.com 2015-09-14T08:09:31+00:00 e52ea4cc8b0298e06c28469c8e8b8d9cecaed0f3 commit 005efedf2c7d0a270ffbe28d8997b03844f3e3e7 upstream. If a file has a range pointing to a compressed extent, followed by another range that points to the same compressed extent and a read operation attempts to read both ranges (either completely or part of them), the pages that correspond to the second range are incorrectly filled with zeroes. Consider the following example: File layout [0 - 8K] [8K - 24K] | | | | points to extent X, points to extent X, offset 4K, length of 8K offset 0, length 16K [extent X, compressed length = 4K uncompressed length = 16K] If a readpages() call spans the 2 ranges, a single bio to read the extent is submitted - extent_io.c:submit_extent_page() would only create a new bio to cover the second range pointing to the extent if the extent it points to had a different logical address than the extent associated with the first range. This has a consequence of the compressed read end io handler (compression.c:end_compressed_bio_read()) finish once the extent is decompressed into the pages covering the first range, leaving the remaining pages (belonging to the second range) filled with zeroes (done by compression.c:btrfs_clear_biovec_end()). So fix this by submitting the current bio whenever we find a range pointing to a compressed extent that was preceded by a range with a different extent map. This is the simplest solution for this corner case. Making the end io callback populate both ranges (or more, if we have multiple pointing to the same extent) is a much more complex solution since each bio is tightly coupled with a single extent map and the extent maps associated to the ranges pointing to the shared extent can have different offsets and lengths. The following test case for fstests triggers the issue: seq=`basename $0` seqres=$RESULT_DIR/$seq echo "QA output created by $seq" tmp=/tmp/$$ status=1 # failure is the default! trap "_cleanup; exit \$status" 0 1 2 3 15 _cleanup() { rm -f $tmp.* } # get standard environment, filters and checks . ./common/rc . ./common/filter # real QA test starts here _need_to_be_root _supported_fs btrfs _supported_os Linux _require_scratch _require_cloner rm -f $seqres.full test_clone_and_read_compressed_extent() { local mount_opts=$1 _scratch_mkfs >>$seqres.full 2>&1 _scratch_mount $mount_opts # Create a test file with a single extent that is compressed (the # data we write into it is highly compressible no matter which # compression algorithm is used, zlib or lzo). $XFS_IO_PROG -f -c "pwrite -S 0xaa 0K 4K" \ -c "pwrite -S 0xbb 4K 8K" \ -c "pwrite -S 0xcc 12K 4K" \ $SCRATCH_MNT/foo | _filter_xfs_io # Now clone our extent into an adjacent offset. $CLONER_PROG -s $((4 * 1024)) -d $((16 * 1024)) -l $((8 * 1024)) \ $SCRATCH_MNT/foo $SCRATCH_MNT/foo # Same as before but for this file we clone the extent into a lower # file offset. $XFS_IO_PROG -f -c "pwrite -S 0xaa 8K 4K" \ -c "pwrite -S 0xbb 12K 8K" \ -c "pwrite -S 0xcc 20K 4K" \ $SCRATCH_MNT/bar | _filter_xfs_io $CLONER_PROG -s $((12 * 1024)) -d 0 -l $((8 * 1024)) \ $SCRATCH_MNT/bar $SCRATCH_MNT/bar echo "File digests before unmounting filesystem:" md5sum $SCRATCH_MNT/foo | _filter_scratch md5sum $SCRATCH_MNT/bar | _filter_scratch # Evicting the inode or clearing the page cache before reading # again the file would also trigger the bug - reads were returning # all bytes in the range corresponding to the second reference to # the extent with a value of 0, but the correct data was persisted # (it was a bug exclusively in the read path). The issue happened # only if the same readpages() call targeted pages belonging to the # first and second ranges that point to the same compressed extent. _scratch_remount echo "File digests after mounting filesystem again:" # Must match the same digests we got before. md5sum $SCRATCH_MNT/foo | _filter_scratch md5sum $SCRATCH_MNT/bar | _filter_scratch } echo -e "\nTesting with zlib compression..." test_clone_and_read_compressed_extent "-o compress=zlib" _scratch_unmount echo -e "\nTesting with lzo compression..." test_clone_and_read_compressed_extent "-o compress=lzo" status=0 exit Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: Qu Wenruo<quwenruo@cn.fujitsu.com> Reviewed-by: Liu Bo <bo.li.liu@oracle.com> [bwh: Backported to 3.2: - Maintain prev_em_start in both functions calling __extent_read_full_page() in a loop - Adjust context and order] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 005efedf2c7d0a270ffbe28d8997b03844f3e3e7 upstream.

If a file has a range pointing to a compressed extent, followed by
another range that points to the same compressed extent and a read
operation attempts to read both ranges (either completely or part of
them), the pages that correspond to the second range are incorrectly
filled with zeroes.

Consider the following example:

  File layout
  [0 - 8K]                      [8K - 24K]
      |                             |
      |                             |
   points to extent X,         points to extent X,
   offset 4K, length of 8K     offset 0, length 16K

  [extent X, compressed length = 4K uncompressed length = 16K]

If a readpages() call spans the 2 ranges, a single bio to read the extent
is submitted - extent_io.c:submit_extent_page() would only create a new
bio to cover the second range pointing to the extent if the extent it
points to had a different logical address than the extent associated with
the first range. This has a consequence of the compressed read end io
handler (compression.c:end_compressed_bio_read()) finish once the extent
is decompressed into the pages covering the first range, leaving the
remaining pages (belonging to the second range) filled with zeroes (done
by compression.c:btrfs_clear_biovec_end()).

So fix this by submitting the current bio whenever we find a range
pointing to a compressed extent that was preceded by a range with a
different extent map. This is the simplest solution for this corner
case. Making the end io callback populate both ranges (or more, if we
have multiple pointing to the same extent) is a much more complex
solution since each bio is tightly coupled with a single extent map and
the extent maps associated to the ranges pointing to the shared extent
can have different offsets and lengths.

The following test case for fstests triggers the issue:

  seq=`basename $0`
  seqres=$RESULT_DIR/$seq
  echo "QA output created by $seq"
  tmp=/tmp/$$
  status=1	# failure is the default!
  trap "_cleanup; exit \$status" 0 1 2 3 15

  _cleanup()
  {
      rm -f $tmp.*
  }

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

  # real QA test starts here
  _need_to_be_root
  _supported_fs btrfs
  _supported_os Linux
  _require_scratch
  _require_cloner

  rm -f $seqres.full

  test_clone_and_read_compressed_extent()
  {
      local mount_opts=$1

      _scratch_mkfs >>$seqres.full 2>&1
      _scratch_mount $mount_opts

      # Create a test file with a single extent that is compressed (the
      # data we write into it is highly compressible no matter which
      # compression algorithm is used, zlib or lzo).
      $XFS_IO_PROG -f -c "pwrite -S 0xaa 0K 4K"        \
                      -c "pwrite -S 0xbb 4K 8K"        \
                      -c "pwrite -S 0xcc 12K 4K"       \
                      $SCRATCH_MNT/foo | _filter_xfs_io

      # Now clone our extent into an adjacent offset.
      $CLONER_PROG -s $((4 * 1024)) -d $((16 * 1024)) -l $((8 * 1024)) \
          $SCRATCH_MNT/foo $SCRATCH_MNT/foo

      # Same as before but for this file we clone the extent into a lower
      # file offset.
      $XFS_IO_PROG -f -c "pwrite -S 0xaa 8K 4K"         \
                      -c "pwrite -S 0xbb 12K 8K"        \
                      -c "pwrite -S 0xcc 20K 4K"        \
                      $SCRATCH_MNT/bar | _filter_xfs_io

      $CLONER_PROG -s $((12 * 1024)) -d 0 -l $((8 * 1024)) \
          $SCRATCH_MNT/bar $SCRATCH_MNT/bar

      echo "File digests before unmounting filesystem:"
      md5sum $SCRATCH_MNT/foo | _filter_scratch
      md5sum $SCRATCH_MNT/bar | _filter_scratch

      # Evicting the inode or clearing the page cache before reading
      # again the file would also trigger the bug - reads were returning
      # all bytes in the range corresponding to the second reference to
      # the extent with a value of 0, but the correct data was persisted
      # (it was a bug exclusively in the read path). The issue happened
      # only if the same readpages() call targeted pages belonging to the
      # first and second ranges that point to the same compressed extent.
      _scratch_remount

      echo "File digests after mounting filesystem again:"
      # Must match the same digests we got before.
      md5sum $SCRATCH_MNT/foo | _filter_scratch
      md5sum $SCRATCH_MNT/bar | _filter_scratch
  }

  echo -e "\nTesting with zlib compression..."
  test_clone_and_read_compressed_extent "-o compress=zlib"

  _scratch_unmount

  echo -e "\nTesting with lzo compression..."
  test_clone_and_read_compressed_extent "-o compress=lzo"

  status=0
  exit

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Qu Wenruo<quwenruo@cn.fujitsu.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
[bwh: Backported to 3.2:
 - Maintain prev_em_start in both functions calling __extent_read_full_page()
   in a loop
 - Adjust context and order]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Btrfs: fix file corruption after cloning inline extents 2015-08-12T14:33:21+00:00 Filipe Manana fdmanana@suse.com 2015-07-14T15:09:39+00:00 ea1f670125b9047bc30f7fd42231b05315dffd58 commit ed958762644b404654a6f5d23e869f496fe127c6 upstream. Using the clone ioctl (or extent_same ioctl, which calls the same extent cloning function as well) we end up allowing copy an inline extent from the source file into a non-zero offset of the destination file. This is something not expected and that the btrfs code is not prepared to deal with - all inline extents must be at a file offset equals to 0. For example, the following excerpt of a test case for fstests triggers a crash/BUG_ON() on a write operation after an inline extent is cloned into a non-zero offset: _scratch_mkfs >>$seqres.full 2>&1 _scratch_mount # Create our test files. File foo has the same 2K of data at offset 4K # as file bar has at its offset 0. $XFS_IO_PROG -f -s -c "pwrite -S 0xaa 0 4K" \ -c "pwrite -S 0xbb 4k 2K" \ -c "pwrite -S 0xcc 8K 4K" \ $SCRATCH_MNT/foo | _filter_xfs_io # File bar consists of a single inline extent (2K size). $XFS_IO_PROG -f -s -c "pwrite -S 0xbb 0 2K" \ $SCRATCH_MNT/bar | _filter_xfs_io # Now call the clone ioctl to clone the extent of file bar into file # foo at its offset 4K. This made file foo have an inline extent at # offset 4K, something which the btrfs code can not deal with in future # IO operations because all inline extents are supposed to start at an # offset of 0, resulting in all sorts of chaos. # So here we validate that clone ioctl returns an EOPNOTSUPP, which is # what it returns for other cases dealing with inlined extents. $CLONER_PROG -s 0 -d $((4 * 1024)) -l $((2 * 1024)) \ $SCRATCH_MNT/bar $SCRATCH_MNT/foo # Because of the inline extent at offset 4K, the following write made # the kernel crash with a BUG_ON(). $XFS_IO_PROG -c "pwrite -S 0xdd 6K 2K" $SCRATCH_MNT/foo | _filter_xfs_io status=0 exit The stack trace of the BUG_ON() triggered by the last write is: [152154.035903] ------------[ cut here ]------------ [152154.036424] kernel BUG at mm/page-writeback.c:2286! [152154.036424] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC [152154.036424] Modules linked in: btrfs dm_flakey dm_mod crc32c_generic xor raid6_pq nfsd auth_rpcgss oid_registry nfs_acl nfs lockd grace fscache sunrpc loop fuse parport_pc acpi_cpu$ [152154.036424] CPU: 2 PID: 17873 Comm: xfs_io Tainted: G W 4.1.0-rc6-btrfs-next-11+ #2 [152154.036424] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.8.1-0-g4adadbd-20150316_085822-nilsson.home.kraxel.org 04/01/2014 [152154.036424] task: ffff880429f70990 ti: ffff880429efc000 task.ti: ffff880429efc000 [152154.036424] RIP: 0010:[<ffffffff8111a9d5>] [<ffffffff8111a9d5>] clear_page_dirty_for_io+0x1e/0x90 [152154.036424] RSP: 0018:ffff880429effc68 EFLAGS: 00010246 [152154.036424] RAX: 0200000000000806 RBX: ffffea0006a6d8f0 RCX: 0000000000000001 [152154.036424] RDX: 0000000000000000 RSI: ffffffff81155d1b RDI: ffffea0006a6d8f0 [152154.036424] RBP: ffff880429effc78 R08: ffff8801ce389fe0 R09: 0000000000000001 [152154.036424] R10: 0000000000002000 R11: ffffffffffffffff R12: ffff8800200dce68 [152154.036424] R13: 0000000000000000 R14: ffff8800200dcc88 R15: ffff8803d5736d80 [152154.036424] FS: 00007fbf119f6700(0000) GS:ffff88043d280000(0000) knlGS:0000000000000000 [152154.036424] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [152154.036424] CR2: 0000000001bdc000 CR3: 00000003aa555000 CR4: 00000000000006e0 [152154.036424] Stack: [152154.036424] ffff8803d5736d80 0000000000000001 ffff880429effcd8 ffffffffa04e97c1 [152154.036424] ffff880429effd68 ffff880429effd60 0000000000000001 ffff8800200dc9c8 [152154.036424] 0000000000000001 ffff8800200dcc88 0000000000000000 0000000000001000 [152154.036424] Call Trace: [152154.036424] [<ffffffffa04e97c1>] lock_and_cleanup_extent_if_need+0x147/0x18d [btrfs] [152154.036424] [<ffffffffa04ea82c>] __btrfs_buffered_write+0x245/0x4c8 [btrfs] [152154.036424] [<ffffffffa04ed14b>] ? btrfs_file_write_iter+0x150/0x3e0 [btrfs] [152154.036424] [<ffffffffa04ed15a>] ? btrfs_file_write_iter+0x15f/0x3e0 [btrfs] [152154.036424] [<ffffffffa04ed2c7>] btrfs_file_write_iter+0x2cc/0x3e0 [btrfs] [152154.036424] [<ffffffff81165a4a>] __vfs_write+0x7c/0xa5 [152154.036424] [<ffffffff81165f89>] vfs_write+0xa0/0xe4 [152154.036424] [<ffffffff81166855>] SyS_pwrite64+0x64/0x82 [152154.036424] [<ffffffff81465197>] system_call_fastpath+0x12/0x6f [152154.036424] Code: 48 89 c7 e8 0f ff ff ff 5b 41 5c 5d c3 0f 1f 44 00 00 55 48 89 e5 41 54 53 48 89 fb e8 ae ef 00 00 49 89 c4 48 8b 03 a8 01 75 02 <0f> 0b 4d 85 e4 74 59 49 8b 3c 2$ [152154.036424] RIP [<ffffffff8111a9d5>] clear_page_dirty_for_io+0x1e/0x90 [152154.036424] RSP <ffff880429effc68> [152154.242621] ---[ end trace e3d3376b23a57041 ]--- Fix this by returning the error EOPNOTSUPP if an attempt to copy an inline extent into a non-zero offset happens, just like what is done for other scenarios that would require copying/splitting inline extents, which were introduced by the following commits: 00fdf13a2e9f ("Btrfs: fix a crash of clone with inline extents's split") 3f9e3df8da3c ("btrfs: replace error code from btrfs_drop_extents") Signed-off-by: Filipe Manana <fdmanana@suse.com> [bwh: Backported to 3.2: test new_key.offset as last_dest_end isn't defined in this function] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit ed958762644b404654a6f5d23e869f496fe127c6 upstream.

Using the clone ioctl (or extent_same ioctl, which calls the same extent
cloning function as well) we end up allowing copy an inline extent from
the source file into a non-zero offset of the destination file. This is
something not expected and that the btrfs code is not prepared to deal
with - all inline extents must be at a file offset equals to 0.

For example, the following excerpt of a test case for fstests triggers
a crash/BUG_ON() on a write operation after an inline extent is cloned
into a non-zero offset:

  _scratch_mkfs >>$seqres.full 2>&1
  _scratch_mount

  # Create our test files. File foo has the same 2K of data at offset 4K
  # as file bar has at its offset 0.
  $XFS_IO_PROG -f -s -c "pwrite -S 0xaa 0 4K" \
      -c "pwrite -S 0xbb 4k 2K" \
      -c "pwrite -S 0xcc 8K 4K" \
      $SCRATCH_MNT/foo | _filter_xfs_io

  # File bar consists of a single inline extent (2K size).
  $XFS_IO_PROG -f -s -c "pwrite -S 0xbb 0 2K" \
     $SCRATCH_MNT/bar | _filter_xfs_io

  # Now call the clone ioctl to clone the extent of file bar into file
  # foo at its offset 4K. This made file foo have an inline extent at
  # offset 4K, something which the btrfs code can not deal with in future
  # IO operations because all inline extents are supposed to start at an
  # offset of 0, resulting in all sorts of chaos.
  # So here we validate that clone ioctl returns an EOPNOTSUPP, which is
  # what it returns for other cases dealing with inlined extents.
  $CLONER_PROG -s 0 -d $((4 * 1024)) -l $((2 * 1024)) \
      $SCRATCH_MNT/bar $SCRATCH_MNT/foo

  # Because of the inline extent at offset 4K, the following write made
  # the kernel crash with a BUG_ON().
  $XFS_IO_PROG -c "pwrite -S 0xdd 6K 2K" $SCRATCH_MNT/foo | _filter_xfs_io

  status=0
  exit

The stack trace of the BUG_ON() triggered by the last write is:

  [152154.035903] ------------[ cut here ]------------
  [152154.036424] kernel BUG at mm/page-writeback.c:2286!
  [152154.036424] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
  [152154.036424] Modules linked in: btrfs dm_flakey dm_mod crc32c_generic xor raid6_pq nfsd auth_rpcgss oid_registry nfs_acl nfs lockd grace fscache sunrpc loop fuse parport_pc acpi_cpu$
  [152154.036424] CPU: 2 PID: 17873 Comm: xfs_io Tainted: G        W       4.1.0-rc6-btrfs-next-11+ #2
  [152154.036424] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.8.1-0-g4adadbd-20150316_085822-nilsson.home.kraxel.org 04/01/2014
  [152154.036424] task: ffff880429f70990 ti: ffff880429efc000 task.ti: ffff880429efc000
  [152154.036424] RIP: 0010:[<ffffffff8111a9d5>]  [<ffffffff8111a9d5>] clear_page_dirty_for_io+0x1e/0x90
  [152154.036424] RSP: 0018:ffff880429effc68  EFLAGS: 00010246
  [152154.036424] RAX: 0200000000000806 RBX: ffffea0006a6d8f0 RCX: 0000000000000001
  [152154.036424] RDX: 0000000000000000 RSI: ffffffff81155d1b RDI: ffffea0006a6d8f0
  [152154.036424] RBP: ffff880429effc78 R08: ffff8801ce389fe0 R09: 0000000000000001
  [152154.036424] R10: 0000000000002000 R11: ffffffffffffffff R12: ffff8800200dce68
  [152154.036424] R13: 0000000000000000 R14: ffff8800200dcc88 R15: ffff8803d5736d80
  [152154.036424] FS:  00007fbf119f6700(0000) GS:ffff88043d280000(0000) knlGS:0000000000000000
  [152154.036424] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  [152154.036424] CR2: 0000000001bdc000 CR3: 00000003aa555000 CR4: 00000000000006e0
  [152154.036424] Stack:
  [152154.036424]  ffff8803d5736d80 0000000000000001 ffff880429effcd8 ffffffffa04e97c1
  [152154.036424]  ffff880429effd68 ffff880429effd60 0000000000000001 ffff8800200dc9c8
  [152154.036424]  0000000000000001 ffff8800200dcc88 0000000000000000 0000000000001000
  [152154.036424] Call Trace:
  [152154.036424]  [<ffffffffa04e97c1>] lock_and_cleanup_extent_if_need+0x147/0x18d [btrfs]
  [152154.036424]  [<ffffffffa04ea82c>] __btrfs_buffered_write+0x245/0x4c8 [btrfs]
  [152154.036424]  [<ffffffffa04ed14b>] ? btrfs_file_write_iter+0x150/0x3e0 [btrfs]
  [152154.036424]  [<ffffffffa04ed15a>] ? btrfs_file_write_iter+0x15f/0x3e0 [btrfs]
  [152154.036424]  [<ffffffffa04ed2c7>] btrfs_file_write_iter+0x2cc/0x3e0 [btrfs]
  [152154.036424]  [<ffffffff81165a4a>] __vfs_write+0x7c/0xa5
  [152154.036424]  [<ffffffff81165f89>] vfs_write+0xa0/0xe4
  [152154.036424]  [<ffffffff81166855>] SyS_pwrite64+0x64/0x82
  [152154.036424]  [<ffffffff81465197>] system_call_fastpath+0x12/0x6f
  [152154.036424] Code: 48 89 c7 e8 0f ff ff ff 5b 41 5c 5d c3 0f 1f 44 00 00 55 48 89 e5 41 54 53 48 89 fb e8 ae ef 00 00 49 89 c4 48 8b 03 a8 01 75 02 <0f> 0b 4d 85 e4 74 59 49 8b 3c 2$
  [152154.036424] RIP  [<ffffffff8111a9d5>] clear_page_dirty_for_io+0x1e/0x90
  [152154.036424]  RSP <ffff880429effc68>
  [152154.242621] ---[ end trace e3d3376b23a57041 ]---

Fix this by returning the error EOPNOTSUPP if an attempt to copy an
inline extent into a non-zero offset happens, just like what is done for
other scenarios that would require copying/splitting inline extents,
which were introduced by the following commits:

   00fdf13a2e9f ("Btrfs: fix a crash of clone with inline extents's split")
   3f9e3df8da3c ("btrfs: replace error code from btrfs_drop_extents")

Signed-off-by: Filipe Manana <fdmanana@suse.com>
[bwh: Backported to 3.2: test new_key.offset as last_dest_end isn't defined
 in this function]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Btrfs: fix race between caching kthread and returning inode to inode cache 2015-08-12T14:33:18+00:00 Filipe Manana fdmanana@suse.com 2015-06-13T05:52:57+00:00 3e05b16a56a9ffc6cd01d155c8599df7d17a8893 commit ae9d8f17118551bedd797406a6768b87c2146234 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: 1c70d8fb4dfa ("Btrfs: fix inode caching vs tree log") Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Chris Mason <clm@fb.com> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit ae9d8f17118551bedd797406a6768b87c2146234 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: 1c70d8fb4dfa ("Btrfs: fix inode caching vs tree log")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Btrfs: use kmem_cache_free when freeing entry in inode cache 2015-08-12T14:33:18+00:00 Filipe Manana fdmanana@suse.com 2015-06-13T05:52:56+00:00 c6bbfa525c51fd10970b7cb0ed295c5e7ee27511 commit c3f4a1685bb87e59c886ee68f7967eae07d4dffa 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: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.cz> Signed-off-by: Chris Mason <clm@fb.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit c3f4a1685bb87e59c886ee68f7967eae07d4dffa 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: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Btrfs: fix inode eviction infinite loop after cloning into it 2015-08-06T23:32:04+00:00 Filipe Manana fdmanana@suse.com 2015-03-30T17:23:59+00:00 aae89a4f7996bb0f5ded693fb1768f2faa9f4ace commit ccccf3d67294714af2d72a6fd6fd7d73b01c9329 upstream. If we attempt to clone a 0 length region into a file we can end up inserting a range in the inode's extent_io tree with a start offset that is greater then the end offset, which triggers immediately the following warning: [ 3914.619057] WARNING: CPU: 17 PID: 4199 at fs/btrfs/extent_io.c:435 insert_state+0x4b/0x10b [btrfs]() [ 3914.620886] BTRFS: end < start 4095 4096 (...) [ 3914.638093] Call Trace: [ 3914.638636] [<ffffffff81425fd9>] dump_stack+0x4c/0x65 [ 3914.639620] [<ffffffff81045390>] warn_slowpath_common+0xa1/0xbb [ 3914.640789] [<ffffffffa03ca44f>] ? insert_state+0x4b/0x10b [btrfs] [ 3914.642041] [<ffffffff810453f0>] warn_slowpath_fmt+0x46/0x48 [ 3914.643236] [<ffffffffa03ca44f>] insert_state+0x4b/0x10b [btrfs] [ 3914.644441] [<ffffffffa03ca729>] __set_extent_bit+0x107/0x3f4 [btrfs] [ 3914.645711] [<ffffffffa03cb256>] lock_extent_bits+0x65/0x1bf [btrfs] [ 3914.646914] [<ffffffff8142b2fb>] ? _raw_spin_unlock+0x28/0x33 [ 3914.648058] [<ffffffffa03cbac4>] ? test_range_bit+0xcc/0xde [btrfs] [ 3914.650105] [<ffffffffa03cb3c3>] lock_extent+0x13/0x15 [btrfs] [ 3914.651361] [<ffffffffa03db39e>] lock_extent_range+0x3d/0xcd [btrfs] [ 3914.652761] [<ffffffffa03de1fe>] btrfs_ioctl_clone+0x278/0x388 [btrfs] [ 3914.654128] [<ffffffff811226dd>] ? might_fault+0x58/0xb5 [ 3914.655320] [<ffffffffa03e0909>] btrfs_ioctl+0xb51/0x2195 [btrfs] (...) [ 3914.669271] ---[ end trace 14843d3e2e622fc1 ]--- This later makes the inode eviction handler enter an infinite loop that keeps dumping the following warning over and over: [ 3915.117629] WARNING: CPU: 22 PID: 4228 at fs/btrfs/extent_io.c:435 insert_state+0x4b/0x10b [btrfs]() [ 3915.119913] BTRFS: end < start 4095 4096 (...) [ 3915.137394] Call Trace: [ 3915.137913] [<ffffffff81425fd9>] dump_stack+0x4c/0x65 [ 3915.139154] [<ffffffff81045390>] warn_slowpath_common+0xa1/0xbb [ 3915.140316] [<ffffffffa03ca44f>] ? insert_state+0x4b/0x10b [btrfs] [ 3915.141505] [<ffffffff810453f0>] warn_slowpath_fmt+0x46/0x48 [ 3915.142709] [<ffffffffa03ca44f>] insert_state+0x4b/0x10b [btrfs] [ 3915.143849] [<ffffffffa03ca729>] __set_extent_bit+0x107/0x3f4 [btrfs] [ 3915.145120] [<ffffffffa038c1e3>] ? btrfs_kill_super+0x17/0x23 [btrfs] [ 3915.146352] [<ffffffff811548f6>] ? deactivate_locked_super+0x3b/0x50 [ 3915.147565] [<ffffffffa03cb256>] lock_extent_bits+0x65/0x1bf [btrfs] [ 3915.148785] [<ffffffff8142b7e2>] ? _raw_write_unlock+0x28/0x33 [ 3915.149931] [<ffffffffa03bc325>] btrfs_evict_inode+0x196/0x482 [btrfs] [ 3915.151154] [<ffffffff81168904>] evict+0xa0/0x148 [ 3915.152094] [<ffffffff811689e5>] dispose_list+0x39/0x43 [ 3915.153081] [<ffffffff81169564>] evict_inodes+0xdc/0xeb [ 3915.154062] [<ffffffff81154418>] generic_shutdown_super+0x49/0xef [ 3915.155193] [<ffffffff811546d1>] kill_anon_super+0x13/0x1e [ 3915.156274] [<ffffffffa038c1e3>] btrfs_kill_super+0x17/0x23 [btrfs] (...) [ 3915.167404] ---[ end trace 14843d3e2e622fc2 ]--- So just bail out of the clone ioctl if the length of the region to clone is zero, without locking any extent range, in order to prevent this issue (same behaviour as a pwrite with a 0 length for example). This is trivial to reproduce. For example, the steps for the test I just made for fstests: mkfs.btrfs -f SCRATCH_DEV mount SCRATCH_DEV $SCRATCH_MNT touch $SCRATCH_MNT/foo touch $SCRATCH_MNT/bar $CLONER_PROG -s 0 -d 4096 -l 0 $SCRATCH_MNT/foo $SCRATCH_MNT/bar umount $SCRATCH_MNT A test case for fstests follows soon. Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: Omar Sandoval <osandov@osandov.com> Signed-off-by: Chris Mason <clm@fb.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit ccccf3d67294714af2d72a6fd6fd7d73b01c9329 upstream.

If we attempt to clone a 0 length region into a file we can end up
inserting a range in the inode's extent_io tree with a start offset
that is greater then the end offset, which triggers immediately the
following warning:

[ 3914.619057] WARNING: CPU: 17 PID: 4199 at fs/btrfs/extent_io.c:435 insert_state+0x4b/0x10b [btrfs]()
[ 3914.620886] BTRFS: end < start 4095 4096
(...)
[ 3914.638093] Call Trace:
[ 3914.638636]  [<ffffffff81425fd9>] dump_stack+0x4c/0x65
[ 3914.639620]  [<ffffffff81045390>] warn_slowpath_common+0xa1/0xbb
[ 3914.640789]  [<ffffffffa03ca44f>] ? insert_state+0x4b/0x10b [btrfs]
[ 3914.642041]  [<ffffffff810453f0>] warn_slowpath_fmt+0x46/0x48
[ 3914.643236]  [<ffffffffa03ca44f>] insert_state+0x4b/0x10b [btrfs]
[ 3914.644441]  [<ffffffffa03ca729>] __set_extent_bit+0x107/0x3f4 [btrfs]
[ 3914.645711]  [<ffffffffa03cb256>] lock_extent_bits+0x65/0x1bf [btrfs]
[ 3914.646914]  [<ffffffff8142b2fb>] ? _raw_spin_unlock+0x28/0x33
[ 3914.648058]  [<ffffffffa03cbac4>] ? test_range_bit+0xcc/0xde [btrfs]
[ 3914.650105]  [<ffffffffa03cb3c3>] lock_extent+0x13/0x15 [btrfs]
[ 3914.651361]  [<ffffffffa03db39e>] lock_extent_range+0x3d/0xcd [btrfs]
[ 3914.652761]  [<ffffffffa03de1fe>] btrfs_ioctl_clone+0x278/0x388 [btrfs]
[ 3914.654128]  [<ffffffff811226dd>] ? might_fault+0x58/0xb5
[ 3914.655320]  [<ffffffffa03e0909>] btrfs_ioctl+0xb51/0x2195 [btrfs]
(...)
[ 3914.669271] ---[ end trace 14843d3e2e622fc1 ]---

This later makes the inode eviction handler enter an infinite loop that
keeps dumping the following warning over and over:

[ 3915.117629] WARNING: CPU: 22 PID: 4228 at fs/btrfs/extent_io.c:435 insert_state+0x4b/0x10b [btrfs]()
[ 3915.119913] BTRFS: end < start 4095 4096
(...)
[ 3915.137394] Call Trace:
[ 3915.137913]  [<ffffffff81425fd9>] dump_stack+0x4c/0x65
[ 3915.139154]  [<ffffffff81045390>] warn_slowpath_common+0xa1/0xbb
[ 3915.140316]  [<ffffffffa03ca44f>] ? insert_state+0x4b/0x10b [btrfs]
[ 3915.141505]  [<ffffffff810453f0>] warn_slowpath_fmt+0x46/0x48
[ 3915.142709]  [<ffffffffa03ca44f>] insert_state+0x4b/0x10b [btrfs]
[ 3915.143849]  [<ffffffffa03ca729>] __set_extent_bit+0x107/0x3f4 [btrfs]
[ 3915.145120]  [<ffffffffa038c1e3>] ? btrfs_kill_super+0x17/0x23 [btrfs]
[ 3915.146352]  [<ffffffff811548f6>] ? deactivate_locked_super+0x3b/0x50
[ 3915.147565]  [<ffffffffa03cb256>] lock_extent_bits+0x65/0x1bf [btrfs]
[ 3915.148785]  [<ffffffff8142b7e2>] ? _raw_write_unlock+0x28/0x33
[ 3915.149931]  [<ffffffffa03bc325>] btrfs_evict_inode+0x196/0x482 [btrfs]
[ 3915.151154]  [<ffffffff81168904>] evict+0xa0/0x148
[ 3915.152094]  [<ffffffff811689e5>] dispose_list+0x39/0x43
[ 3915.153081]  [<ffffffff81169564>] evict_inodes+0xdc/0xeb
[ 3915.154062]  [<ffffffff81154418>] generic_shutdown_super+0x49/0xef
[ 3915.155193]  [<ffffffff811546d1>] kill_anon_super+0x13/0x1e
[ 3915.156274]  [<ffffffffa038c1e3>] btrfs_kill_super+0x17/0x23 [btrfs]
(...)
[ 3915.167404] ---[ end trace 14843d3e2e622fc2 ]---

So just bail out of the clone ioctl if the length of the region to clone
is zero, without locking any extent range, in order to prevent this issue
(same behaviour as a pwrite with a 0 length for example).

This is trivial to reproduce. For example, the steps for the test I just
made for fstests:

  mkfs.btrfs -f SCRATCH_DEV
  mount SCRATCH_DEV $SCRATCH_MNT

  touch $SCRATCH_MNT/foo
  touch $SCRATCH_MNT/bar

  $CLONER_PROG -s 0 -d 4096 -l 0 $SCRATCH_MNT/foo $SCRATCH_MNT/bar
  umount $SCRATCH_MNT

A test case for fstests follows soon.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
btrfs: don't accept bare namespace as a valid xattr 2015-08-06T23:32:01+00:00 David Sterba dsterba@suse.cz 2015-03-25T18:26:41+00:00 07489bed80696168a3e43212f63832e55e18b4ae commit 3c3b04d10ff1811a27f86684ccd2f5ba6983211d upstream. Due to insufficient check in btrfs_is_valid_xattr, this unexpectedly works: $ touch file $ setfattr -n user. -v 1 file $ getfattr -d file user.="1" ie. the missing attribute name after the namespace. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=94291 Reported-by: William Douglas <william.douglas@intel.com> Signed-off-by: David Sterba <dsterba@suse.cz> Signed-off-by: Chris Mason <clm@fb.com> [bwh: Backported to 3.2: XATTR_BTRFS_PREFIX is not supported] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 3c3b04d10ff1811a27f86684ccd2f5ba6983211d upstream.

Due to insufficient check in btrfs_is_valid_xattr, this unexpectedly
works:

 $ touch file
 $ setfattr -n user. -v 1 file
 $ getfattr -d file
user.="1"

ie. the missing attribute name after the namespace.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=94291
Reported-by: William Douglas <william.douglas@intel.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
[bwh: Backported to 3.2: XATTR_BTRFS_PREFIX is not supported]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Btrfs: fix log tree corruption when fs mounted with -o discard 2015-08-06T23:32:01+00:00 Filipe Manana fdmanana@suse.com 2015-03-23T14:07:40+00:00 d7aac3477aa40744eb9c101a163a910d4bc7b27a commit dcc82f4783ad91d4ab654f89f37ae9291cdc846a upstream. While committing a transaction we free the log roots before we write the new super block. Freeing the log roots implies marking the disk location of every node/leaf (metadata extent) as pinned before the new super block is written. This is to prevent the disk location of log metadata extents from being reused before the new super block is written, otherwise we would have a corrupted log tree if before the new super block is written a crash/reboot happens and the location of any log tree metadata extent ended up being reused and rewritten. Even though we pinned the log tree's metadata extents, we were issuing a discard against them if the fs was mounted with the -o discard option, resulting in corruption of the log tree if a crash/reboot happened before writing the new super block - the next time the fs was mounted, during the log replay process we would find nodes/leafs of the log btree with a content full of zeroes, causing the process to fail and require the use of the tool btrfs-zero-log to wipeout the log tree (and all data previously fsynced becoming lost forever). Fix this by not doing a discard when pinning an extent. The discard will be done later when it's safe (after the new super block is committed) at extent-tree.c:btrfs_finish_extent_commit(). Fixes: e688b7252f78 (Btrfs: fix extent pinning bugs in the tree log) Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Chris Mason <clm@fb.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit dcc82f4783ad91d4ab654f89f37ae9291cdc846a upstream.

While committing a transaction we free the log roots before we write the
new super block. Freeing the log roots implies marking the disk location
of every node/leaf (metadata extent) as pinned before the new super block
is written. This is to prevent the disk location of log metadata extents
from being reused before the new super block is written, otherwise we
would have a corrupted log tree if before the new super block is written
a crash/reboot happens and the location of any log tree metadata extent
ended up being reused and rewritten.

Even though we pinned the log tree's metadata extents, we were issuing a
discard against them if the fs was mounted with the -o discard option,
resulting in corruption of the log tree if a crash/reboot happened before
writing the new super block - the next time the fs was mounted, during
the log replay process we would find nodes/leafs of the log btree with
a content full of zeroes, causing the process to fail and require the
use of the tool btrfs-zero-log to wipeout the log tree (and all data
previously fsynced becoming lost forever).

Fix this by not doing a discard when pinning an extent. The discard will
be done later when it's safe (after the new super block is committed) at
extent-tree.c:btrfs_finish_extent_commit().

Fixes: e688b7252f78 (Btrfs: fix extent pinning bugs in the tree log)
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Btrfs: fix fs corruption on transaction abort if device supports discard 2015-02-20T00:49:30+00:00 Filipe Manana fdmanana@suse.com 2014-12-07T21:31:47+00:00 ef8977c12383dcd642c33c047ac65d95270fcb1f commit 678886bdc6378c1cbd5072da2c5a3035000214e3 upstream. When we abort a transaction we iterate over all the ranges marked as dirty in fs_info->freed_extents[0] and fs_info->freed_extents[1], clear them from those trees, add them back (unpin) to the free space caches and, if the fs was mounted with "-o discard", perform a discard on those regions. Also, after adding the regions to the free space caches, a fitrim ioctl call can see those ranges in a block group's free space cache and perform a discard on the ranges, so the same issue can happen without "-o discard" as well. This causes corruption, affecting one or multiple btree nodes (in the worst case leaving the fs unmountable) because some of those ranges (the ones in the fs_info->pinned_extents tree) correspond to btree nodes/leafs that are referred by the last committed super block - breaking the rule that anything that was committed by a transaction is untouched until the next transaction commits successfully. I ran into this while running in a loop (for several hours) the fstest that I recently submitted: [PATCH] fstests: add btrfs test to stress chunk allocation/removal and fstrim The corruption always happened when a transaction aborted and then fsck complained like this: _check_btrfs_filesystem: filesystem on /dev/sdc is inconsistent *** fsck.btrfs output *** Check tree block failed, want=94945280, have=0 Check tree block failed, want=94945280, have=0 Check tree block failed, want=94945280, have=0 Check tree block failed, want=94945280, have=0 Check tree block failed, want=94945280, have=0 read block failed check_tree_block Couldn't open file system In this case 94945280 corresponded to the root of a tree. Using frace what I observed was the following sequence of steps happened: 1) transaction N started, fs_info->pinned_extents pointed to fs_info->freed_extents[0]; 2) node/eb 94945280 is created; 3) eb is persisted to disk; 4) transaction N commit starts, fs_info->pinned_extents now points to fs_info->freed_extents[1], and transaction N completes; 5) transaction N + 1 starts; 6) eb is COWed, and btrfs_free_tree_block() called for this eb; 7) eb range (94945280 to 94945280 + 16Kb) is added to fs_info->pinned_extents (fs_info->freed_extents[1]); 8) Something goes wrong in transaction N + 1, like hitting ENOSPC for example, and the transaction is aborted, turning the fs into readonly mode. The stack trace I got for example: [112065.253935] [<ffffffff8140c7b6>] dump_stack+0x4d/0x66 [112065.254271] [<ffffffff81042984>] warn_slowpath_common+0x7f/0x98 [112065.254567] [<ffffffffa0325990>] ? __btrfs_abort_transaction+0x50/0x10b [btrfs] [112065.261674] [<ffffffff810429e5>] warn_slowpath_fmt+0x48/0x50 [112065.261922] [<ffffffffa032949e>] ? btrfs_free_path+0x26/0x29 [btrfs] [112065.262211] [<ffffffffa0325990>] __btrfs_abort_transaction+0x50/0x10b [btrfs] [112065.262545] [<ffffffffa036b1d6>] btrfs_remove_chunk+0x537/0x58b [btrfs] [112065.262771] [<ffffffffa033840f>] btrfs_delete_unused_bgs+0x1de/0x21b [btrfs] [112065.263105] [<ffffffffa0343106>] cleaner_kthread+0x100/0x12f [btrfs] (...) [112065.264493] ---[ end trace dd7903a975a31a08 ]--- [112065.264673] BTRFS: error (device sdc) in btrfs_remove_chunk:2625: errno=-28 No space left [112065.264997] BTRFS info (device sdc): forced readonly 9) The clear kthread sees that the BTRFS_FS_STATE_ERROR bit is set in fs_info->fs_state and calls btrfs_cleanup_transaction(), which in turn calls btrfs_destroy_pinned_extent(); 10) Then btrfs_destroy_pinned_extent() iterates over all the ranges marked as dirty in fs_info->freed_extents[], and for each one it calls discard, if the fs was mounted with "-o discard", and adds the range to the free space cache of the respective block group; 11) btrfs_trim_block_group(), invoked from the fitrim ioctl code path, sees the free space entries and performs a discard; 12) After an umount and mount (or fsck), our eb's location on disk was full of zeroes, and it should have been untouched, because it was marked as dirty in the fs_info->pinned_extents tree, and therefore used by the trees that the last committed superblock points to. Fix this by not performing a discard and not adding the ranges to the free space caches - it's useless from this point since the fs is now in readonly mode and we won't write free space caches to disk anymore (otherwise we would leak space) nor any new superblock. By not adding the ranges to the free space caches, it prevents other code paths from allocating that space and write to it as well, therefore being safer and simpler. This isn't a new problem, as it's been present since 2011 (git commit acce952b0263825da32cf10489413dec78053347). Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Chris Mason <clm@fb.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 678886bdc6378c1cbd5072da2c5a3035000214e3 upstream.

When we abort a transaction we iterate over all the ranges marked as dirty
in fs_info->freed_extents[0] and fs_info->freed_extents[1], clear them
from those trees, add them back (unpin) to the free space caches and, if
the fs was mounted with "-o discard", perform a discard on those regions.
Also, after adding the regions to the free space caches, a fitrim ioctl call
can see those ranges in a block group's free space cache and perform a discard
on the ranges, so the same issue can happen without "-o discard" as well.

This causes corruption, affecting one or multiple btree nodes (in the worst
case leaving the fs unmountable) because some of those ranges (the ones in
the fs_info->pinned_extents tree) correspond to btree nodes/leafs that are
referred by the last committed super block - breaking the rule that anything
that was committed by a transaction is untouched until the next transaction
commits successfully.

I ran into this while running in a loop (for several hours) the fstest that
I recently submitted:

  [PATCH] fstests: add btrfs test to stress chunk allocation/removal and fstrim

The corruption always happened when a transaction aborted and then fsck complained
like this:

   _check_btrfs_filesystem: filesystem on /dev/sdc is inconsistent
   *** fsck.btrfs output ***
   Check tree block failed, want=94945280, have=0
   Check tree block failed, want=94945280, have=0
   Check tree block failed, want=94945280, have=0
   Check tree block failed, want=94945280, have=0
   Check tree block failed, want=94945280, have=0
   read block failed check_tree_block
   Couldn't open file system

In this case 94945280 corresponded to the root of a tree.
Using frace what I observed was the following sequence of steps happened:

   1) transaction N started, fs_info->pinned_extents pointed to
      fs_info->freed_extents[0];

   2) node/eb 94945280 is created;

   3) eb is persisted to disk;

   4) transaction N commit starts, fs_info->pinned_extents now points to
      fs_info->freed_extents[1], and transaction N completes;

   5) transaction N + 1 starts;

   6) eb is COWed, and btrfs_free_tree_block() called for this eb;

   7) eb range (94945280 to 94945280 + 16Kb) is added to
      fs_info->pinned_extents (fs_info->freed_extents[1]);

   8) Something goes wrong in transaction N + 1, like hitting ENOSPC
      for example, and the transaction is aborted, turning the fs into
      readonly mode. The stack trace I got for example:

      [112065.253935]  [<ffffffff8140c7b6>] dump_stack+0x4d/0x66
      [112065.254271]  [<ffffffff81042984>] warn_slowpath_common+0x7f/0x98
      [112065.254567]  [<ffffffffa0325990>] ? __btrfs_abort_transaction+0x50/0x10b [btrfs]
      [112065.261674]  [<ffffffff810429e5>] warn_slowpath_fmt+0x48/0x50
      [112065.261922]  [<ffffffffa032949e>] ? btrfs_free_path+0x26/0x29 [btrfs]
      [112065.262211]  [<ffffffffa0325990>] __btrfs_abort_transaction+0x50/0x10b [btrfs]
      [112065.262545]  [<ffffffffa036b1d6>] btrfs_remove_chunk+0x537/0x58b [btrfs]
      [112065.262771]  [<ffffffffa033840f>] btrfs_delete_unused_bgs+0x1de/0x21b [btrfs]
      [112065.263105]  [<ffffffffa0343106>] cleaner_kthread+0x100/0x12f [btrfs]
      (...)
      [112065.264493] ---[ end trace dd7903a975a31a08 ]---
      [112065.264673] BTRFS: error (device sdc) in btrfs_remove_chunk:2625: errno=-28 No space left
      [112065.264997] BTRFS info (device sdc): forced readonly

   9) The clear kthread sees that the BTRFS_FS_STATE_ERROR bit is set in
      fs_info->fs_state and calls btrfs_cleanup_transaction(), which in
      turn calls btrfs_destroy_pinned_extent();

   10) Then btrfs_destroy_pinned_extent() iterates over all the ranges
       marked as dirty in fs_info->freed_extents[], and for each one
       it calls discard, if the fs was mounted with "-o discard", and
       adds the range to the free space cache of the respective block
       group;

   11) btrfs_trim_block_group(), invoked from the fitrim ioctl code path,
       sees the free space entries and performs a discard;

   12) After an umount and mount (or fsck), our eb's location on disk was full
       of zeroes, and it should have been untouched, because it was marked as
       dirty in the fs_info->pinned_extents tree, and therefore used by the
       trees that the last committed superblock points to.

Fix this by not performing a discard and not adding the ranges to the free space
caches - it's useless from this point since the fs is now in readonly mode and
we won't write free space caches to disk anymore (otherwise we would leak space)
nor any new superblock. By not adding the ranges to the free space caches, it
prevents other code paths from allocating that space and write to it as well,
therefore being safer and simpler.

This isn't a new problem, as it's been present since 2011 (git commit
acce952b0263825da32cf10489413dec78053347).

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Btrfs: fix csum tree corruption, duplicate and outdated checksums 2014-09-13T22:41:44+00:00 Filipe Manana fdmanana@suse.com 2014-08-09T20:22:27+00:00 b055da332c8bbe143214a477cebc3ffc357c64f9 commit 27b9a8122ff71a8cadfbffb9c4f0694300464f3b upstream. Under rare circumstances we can end up leaving 2 versions of a checksum for the same file extent range. The reason for this is that after calling btrfs_next_leaf we process slot 0 of the leaf it returns, instead of processing the slot set in path->slots[0]. Most of the time (by far) path->slots[0] is 0, but after btrfs_next_leaf() releases the path and before it searches for the next leaf, another task might cause a split of the next leaf, which migrates some of its keys to the leaf we were processing before calling btrfs_next_leaf(). In this case btrfs_next_leaf() returns again the same leaf but with path->slots[0] having a slot number corresponding to the first new key it got, that is, a slot number that didn't exist before calling btrfs_next_leaf(), as the leaf now has more keys than it had before. So we must really process the returned leaf starting at path->slots[0] always, as it isn't always 0, and the key at slot 0 can have an offset much lower than our search offset/bytenr. For example, consider the following scenario, where we have: sums->bytenr: 40157184, sums->len: 16384, sums end: 40173568 four 4kb file data blocks with offsets 40157184, 40161280, 40165376, 40169472 Leaf N: slot = 0 slot = btrfs_header_nritems() - 1 |-------------------------------------------------------------------| | [(CSUM CSUM 39239680), size 8] ... [(CSUM CSUM 40116224), size 4] | |-------------------------------------------------------------------| Leaf N + 1: slot = 0 slot = btrfs_header_nritems() - 1 |--------------------------------------------------------------------| | [(CSUM CSUM 40161280), size 32] ... [((CSUM CSUM 40615936), size 8 | |--------------------------------------------------------------------| Because we are at the last slot of leaf N, we call btrfs_next_leaf() to find the next highest key, which releases the current path and then searches for that next key. However after releasing the path and before finding that next key, the item at slot 0 of leaf N + 1 gets moved to leaf N, due to a call to ctree.c:push_leaf_left() (via ctree.c:split_leaf()), and therefore btrfs_next_leaf() will returns us a path again with leaf N but with the slot pointing to its new last key (CSUM CSUM 40161280). This new version of leaf N is then: slot = 0 slot = btrfs_header_nritems() - 2 slot = btrfs_header_nritems() - 1 |----------------------------------------------------------------------------------------------------| | [(CSUM CSUM 39239680), size 8] ... [(CSUM CSUM 40116224), size 4] [(CSUM CSUM 40161280), size 32] | |----------------------------------------------------------------------------------------------------| And incorrecly using slot 0, makes us set next_offset to 39239680 and we jump into the "insert:" label, which will set tmp to: tmp = min((sums->len - total_bytes) >> blocksize_bits, (next_offset - file_key.offset) >> blocksize_bits) = min((16384 - 0) >> 12, (39239680 - 40157184) >> 12) = min(4, (u64)-917504 = 18446744073708634112 >> 12) = 4 and ins_size = csum_size * tmp = 4 * 4 = 16 bytes. In other words, we insert a new csum item in the tree with key (CSUM_OBJECTID CSUM_KEY 40157184 = sums->bytenr) that contains the checksums for all the data (4 blocks of 4096 bytes each = sums->len). Which is wrong, because the item with key (CSUM CSUM 40161280) (the one that was moved from leaf N + 1 to the end of leaf N) contains the old checksums of the last 12288 bytes of our data and won't get those old checksums removed. So this leaves us 2 different checksums for 3 4kb blocks of data in the tree, and breaks the logical rule: Key_N+1.offset >= Key_N.offset + length_of_data_its_checksums_cover An obvious bad effect of this is that a subsequent csum tree lookup to get the checksum of any of the blocks with logical offset of 40161280, 40165376 or 40169472 (the last 3 4kb blocks of file data), will get the old checksums. Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Chris Mason <clm@fb.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 27b9a8122ff71a8cadfbffb9c4f0694300464f3b upstream.

Under rare circumstances we can end up leaving 2 versions of a checksum
for the same file extent range.

The reason for this is that after calling btrfs_next_leaf we process
slot 0 of the leaf it returns, instead of processing the slot set in
path->slots[0]. Most of the time (by far) path->slots[0] is 0, but after
btrfs_next_leaf() releases the path and before it searches for the next
leaf, another task might cause a split of the next leaf, which migrates
some of its keys to the leaf we were processing before calling
btrfs_next_leaf(). In this case btrfs_next_leaf() returns again the
same leaf but with path->slots[0] having a slot number corresponding
to the first new key it got, that is, a slot number that didn't exist
before calling btrfs_next_leaf(), as the leaf now has more keys than
it had before. So we must really process the returned leaf starting at
path->slots[0] always, as it isn't always 0, and the key at slot 0 can
have an offset much lower than our search offset/bytenr.

For example, consider the following scenario, where we have:

sums->bytenr: 40157184, sums->len: 16384, sums end: 40173568
four 4kb file data blocks with offsets 40157184, 40161280, 40165376, 40169472

  Leaf N:

    slot = 0                           slot = btrfs_header_nritems() - 1
  |-------------------------------------------------------------------|
  | [(CSUM CSUM 39239680), size 8] ... [(CSUM CSUM 40116224), size 4] |
  |-------------------------------------------------------------------|

  Leaf N + 1:

      slot = 0                          slot = btrfs_header_nritems() - 1
  |--------------------------------------------------------------------|
  | [(CSUM CSUM 40161280), size 32] ... [((CSUM CSUM 40615936), size 8 |
  |--------------------------------------------------------------------|

Because we are at the last slot of leaf N, we call btrfs_next_leaf() to
find the next highest key, which releases the current path and then searches
for that next key. However after releasing the path and before finding that
next key, the item at slot 0 of leaf N + 1 gets moved to leaf N, due to a call
to ctree.c:push_leaf_left() (via ctree.c:split_leaf()), and therefore
btrfs_next_leaf() will returns us a path again with leaf N but with the slot
pointing to its new last key (CSUM CSUM 40161280). This new version of leaf N
is then:

    slot = 0                        slot = btrfs_header_nritems() - 2  slot = btrfs_header_nritems() - 1
  |----------------------------------------------------------------------------------------------------|
  | [(CSUM CSUM 39239680), size 8] ... [(CSUM CSUM 40116224), size 4]  [(CSUM CSUM 40161280), size 32] |
  |----------------------------------------------------------------------------------------------------|

And incorrecly using slot 0, makes us set next_offset to 39239680 and we jump
into the "insert:" label, which will set tmp to:

    tmp = min((sums->len - total_bytes) >> blocksize_bits,
        (next_offset - file_key.offset) >> blocksize_bits) =
    min((16384 - 0) >> 12, (39239680 - 40157184) >> 12) =
    min(4, (u64)-917504 = 18446744073708634112 >> 12) = 4

and

   ins_size = csum_size * tmp = 4 * 4 = 16 bytes.

In other words, we insert a new csum item in the tree with key
(CSUM_OBJECTID CSUM_KEY 40157184 = sums->bytenr) that contains the checksums
for all the data (4 blocks of 4096 bytes each = sums->len). Which is wrong,
because the item with key (CSUM CSUM 40161280) (the one that was moved from
leaf N + 1 to the end of leaf N) contains the old checksums of the last 12288
bytes of our data and won't get those old checksums removed.

So this leaves us 2 different checksums for 3 4kb blocks of data in the tree,
and breaks the logical rule:

   Key_N+1.offset >= Key_N.offset + length_of_data_its_checksums_cover

An obvious bad effect of this is that a subsequent csum tree lookup to get
the checksum of any of the blocks with logical offset of 40161280, 40165376
or 40169472 (the last 3 4kb blocks of file data), will get the old checksums.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>