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

[ronnie sahlberg]

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