On Fri, Oct 5, 2018 at 3:46 AM Darrick J. Wong <darrick.wong@xxxxxxxxxx> wrote:
>
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Don't bother calling the filesystem for a zero-length dedupe request;
> we can return zero and exit.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> fs/read_write.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
>
> diff --git a/fs/read_write.c b/fs/read_write.c
> index 973d3da78c09..99b2f809180c 100644
> --- a/fs/read_write.c
> +++ b/fs/read_write.c
> @@ -1966,6 +1966,11 @@ int vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
> if (!dst_file->f_op->dedupe_file_range)
> goto out_drop_write;
>
> + if (len == 0) {
> + ret = 0;
> + goto out_drop_write;
> + }
> +
> ret = dst_file->f_op->dedupe_file_range(src_file, src_pos,
> dst_file, dst_pos, len);
I suppose it is best to let user get the same errors he would get
before this change rather than skipping zero length copy at
vfs_dedupe_file_range() level, so looks fine.
Thanks,
Amir.
