On Thu, Jan 27, 2011 at 4:46 PM, Li Zefan <lizf@xxxxxxxxxxxxxx> 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 <lizf@xxxxxxxxxxxxxx>
> ---
> 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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