[SMB3][PATCH] fix copy_file_range when copying beyond end of source file

[Steve French]

Local file systems that I tried, seem to agree with xfstest and return
0 if you try to copy beyond end of src file but do create a zero
length target file

On Wed, Jun 19, 2019 at 9:14 PM ronnie sahlberg
<ronniesahlberg at gmail.com> wrote:
>
> On Thu, Jun 20, 2019 at 11:45 AM Steve French via samba-technical
> <samba-technical at lists.samba.org> wrote:
> >
> > Patch attached fixes the case where copy_file_range over an SMB3 mount
> > tries to go beyond the end of file of the source file.  This fixes
> > xfstests generic/430 and generic/431
> >
> > Amir's patches had added a similar change in the VFS layer, but
> > presumably harmless to have the check in cifs.ko as well to ensure
> > that we don't try to copy beyond end of the source file (otherwise
> > SMB3 servers will return an error on copychunk rather than doing the
> > partial copy (up to end of the source file) that copy_file_range
> > expects).
>
> + if (src_off >= inode->i_size) {
> + cifs_dbg(FYI, "nothing to do on copychunk\n");
> + goto cchunk_out; /* nothing to do */
> + } else if (src_off + len > inode->i_size) {
> + /* consider adding check to see if src oplocked */
> + len = inode->i_size - src_off;
> + cifs_dbg(FYI, "adjust copychunk len %lld less\n", len);
> + }
>
> This makes us return rc == 0 when this triggers. Is that what we want?
> Looking at "man copy_file_range" suggests we should return -EINVAL in
> both these cases.
>
>
>
> >
> >
> >
> > --
> > Thanks,
> >
> > Steve



-- 
Thanks,

Steve