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Btrfs: fix inode eviction infinite loop after extent_same ioctl

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If we pass a length of 0 to the extent_same ioctl, we end up locking an
extent range with a start offset greater then its end offset (if the
destination file's offset is greater than zero). This results in a warning
from extent_io.c:insert_state through the following call chain:

  btrfs_extent_same()
    btrfs_double_lock()
      lock_extent_range()
        lock_extent(inode->io_tree, offset, offset + len - 1)
          lock_extent_bits()
            __set_extent_bit()
              insert_state()
                --> WARN_ON(end < start)

This leads to an infinite loop when evicting the inode. This is the same
problem that my previous patch titled
"Btrfs: fix inode eviction infinite loop after cloning into it" addressed
but for the extent_same ioctl instead of the clone ioctl.

CC: <stable@vger.kernel.org>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Filipe Manana 2015-03-30 18:26:47 +01:00 committed by Chris Mason
parent df858e7672
commit 113e828386
1 changed files with 3 additions and 0 deletions
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3
fs/btrfs/ioctl.c
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@ -2897,6 +2897,9 @@ static int btrfs_extent_same(struct inode *src, u64 loff, u64 len,
if (src == dst)
return -EINVAL;
if (len == 0)
return 0;
btrfs_double_lock(src, loff, dst, dst_loff, len);
ret = extent_same_check_offsets(src, loff, len);