Re: [PATCH 2/2] overlayfs -- follow change to do_splice_direct interface

From: Miklos Szeredi
Date: Thu Jun 27 2013 - 12:37:50 EST


Thanks for the patches, Andy. I already pushed a similar set of fixes
to overlayfs.current (.v18) and to .v17 for the dentry_open() refcount
fix.

On Thu, Jun 27, 2013 at 6:26 PM, Andy Whitcroft <apw@xxxxxxxxxxxxx> wrote:
> The commit below changed the interface to do_splice_direct, follow that
> change in copy_up:
>
> commit 7995bd287134f6c8f80d94bebe7396f05a9bc42b
> Author: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> Date: Thu Jun 20 18:58:36 2013 +0400
>
> splice: don't pass the address of ->f_pos to methods
>
> Signed-off-by: Andy Whitcroft <apw@xxxxxxxxxxxxx>
> ---
> fs/overlayfs/copy_up.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
> index eef85e0..8e1b09f 100644
> --- a/fs/overlayfs/copy_up.c
> +++ b/fs/overlayfs/copy_up.c
> @@ -90,9 +90,10 @@ static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
>
> /* FIXME: copy up sparse files efficiently */
> while (len) {
> - loff_t offset = new_file->f_pos;
> size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
> long bytes;
> + loff_t pos = old_file->f_pos;
> + loff_t out_pos = new_file->f_pos;
>
> if (len < this_len)
> this_len = len;
> @@ -102,7 +103,7 @@ static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
> break;
> }
>
> - bytes = do_splice_direct(old_file, &offset, new_file, this_len,
> + bytes = do_splice_direct(old_file, &pos, new_file, &out_pos, this_len,


It is interesting how many people end up fixing this the wrong way ;)

Hint: how will the file offsets advance?

Thanks,
Miklos
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