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    Subject[PATCH 3.14 09/92] Btrfs: fix inode eviction infinite loop after extent_same ioctl
    Date
    3.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Filipe Manana <fdmanana@suse.com>

    commit 113e8283869b9855c8b999796aadd506bbac155f upstream.

    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.

    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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    fs/btrfs/ioctl.c | 3 +++
    1 file changed, 3 insertions(+)

    --- a/fs/btrfs/ioctl.c
    +++ b/fs/btrfs/ioctl.c
    @@ -2708,6 +2708,9 @@ static int btrfs_extent_same(struct inod
    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);



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