Re: [PATCH 04/11] vfs: add missing checks to copy_file_range

[Olga Kornievskaia <olga.kornievskaia@gmail.com>]

On Wed, Dec 12, 2018 at 6:31 AM Luis Henriques <lhenriques@suse.com> wrote:
>
> Dave Chinner <david@fromorbit.com> writes:
>
> <snip>
>
> > +int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
> > +                      struct file *file_out, loff_t pos_out,
> > +                      size_t *req_count, unsigned int flags)
> > +{
>
> <snip>
>
> > +     /* Don't allow overlapped copying within the same file. */
> > +     if (inode_in == inode_out &&
> > +         pos_out + count > pos_in &&
> > +         pos_out < pos_in + count)
> > +             return -EINVAL;
>
> I was wondering if, with the above check, it would make sense to also
> have an extra patch changing some filesystems (ceph, nfs and cifs) to
> simply return -EOPNOTSUPP (instead of -EINVAL) when inode_in ==
> inode_out.  Something like the diff below (not tested!).
>
> This caught my attention when I was running the latest generic xfstests
> on ceph and realised that I had some new failures due to the recently
> added copy_file_range support in fsx by Darrick.  The failures were
> caused by the usage of the same fd both as source and destination.
>
> Cheers,
> --
> Luis
>
>
> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> index 189df668b6a0..c22ac60ec0ba 100644
> --- a/fs/ceph/file.c
> +++ b/fs/ceph/file.c
> @@ -1904,7 +1904,7 @@ static ssize_t ceph_copy_file_range(struct file *src_file, loff_t src_off,
>         bool do_final_copy = false;
>
>         if (src_inode == dst_inode)
> -               return -EINVAL;
> +               return -EOPNOTSUPP;
>         if (ceph_snap(dst_inode) != CEPH_NOSNAP)
>                 return -EROFS;
>
> diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
> index 865706edb307..d4f63eae531e 100644
> --- a/fs/cifs/cifsfs.c
> +++ b/fs/cifs/cifsfs.c
> @@ -1068,7 +1068,7 @@ ssize_t cifs_file_copychunk_range(unsigned int xid,
>         cifs_dbg(FYI, "copychunk range\n");
>
>         if (src_inode == target_inode) {
> -               rc = -EINVAL;
> +               rc = -EOPNOTSUPP;
>                 goto out;
>         }
>
> diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
> index 46d691ba04bc..910a2abade92 100644
> --- a/fs/nfs/nfs4file.c
> +++ b/fs/nfs/nfs4file.c
> @@ -136,7 +136,7 @@ static ssize_t nfs4_copy_file_range(struct file *file_in, loff_t pos_in,
>         ssize_t ret;
>
>         if (file_inode(file_in) == file_inode(file_out))
> -               return -EINVAL;
> +               return -EOPNOTSUPP;

Please don't change the NFS bits. This is against the NFS
specifications. RFC 7862 15.2.3

(snippet)
SAVED_FH and CURRENT_FH must be different files.  If SAVED_FH and
   CURRENT_FH refer to the same file, the operation MUST fail with
   NFS4ERR_INVAL.

>  retry:
>         ret = nfs42_proc_copy(file_in, pos_in, file_out, pos_out, count);
>         if (ret == -EAGAIN)