On Thu, Jan 27, 2011 at 4:46 PM, Li Zefan <l...@cn.fujitsu.com> wrote:
> Suppose:
> - the source extent is: [0, 100]
> - the src offset is 10
> - the clone length is 90
> - the dest offset is 0
>
> This statement:
>
>        new_key.offset = key.offset + destoff - off
>
> will produce such an extent for the dest file:
>
>        [ino, BTRFS_EXTENT_DATA_KEY, -10]
>
> , which is obviously wrong.
>
> Signed-off-by: Li Zefan <l...@cn.fujitsu.com>
> ---
>  fs/btrfs/ioctl.c |    5 ++++-
>  1 files changed, 4 insertions(+), 1 deletions(-)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index f87552a..1b61dab 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -1788,7 +1788,10 @@ static noinline long btrfs_ioctl_clone(struct file 
> *file, unsigned long srcfd,
>
>                        memcpy(&new_key, &key, sizeof(new_key));
>                        new_key.objectid = inode->i_ino;
> -                       new_key.offset = key.offset + destoff - off;
> +                       if (off <= key.offset)
> +                               new_key.offset = key.offset + destoff - off;
> +                       else
> +                               new_key.offset = destoff;
>
>                        trans = btrfs_start_transaction(root, 1);
>                        if (IS_ERR(trans)) {

This is a disk format change, will cause Oops when deleting or
truncating the file.
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