[PATCH] Do not return number of bytes written for ioctl CIFS_IOC_COPYCHUNK_FILE

[Sachin Prabhu <sprabhu-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

commit 620d8745b35d ("Introduce cifs_copy_file_range()") changes the
behaviour of the cifs ioctl call CIFS_IOC_COPYCHUNK_FILE. In case of
successful writes, it now returns the number of bytes written. This
return value is treated as an error by the xfstest cifs/001. Depending
on the errno set at that time, this may or may not result in the test
failing.

The patch fixes this by setting the return value to 0 in case of
successful writes.

Fixes: commit 620d8745b35d ("Introduce cifs_copy_file_range()")
Reported-by: Eryu Guan <eguan-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Signed-off-by: Sachin Prabhu <sprabhu-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 fs/cifs/ioctl.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/cifs/ioctl.c b/fs/cifs/ioctl.c
index 265c45f..7f4bba5 100644
--- a/fs/cifs/ioctl.c
+++ b/fs/cifs/ioctl.c
@@ -74,7 +74,8 @@ static long cifs_ioctl_copychunk(unsigned int xid, struct file *dst_file,
 
 	rc = cifs_file_copychunk_range(xid, src_file.file, 0, dst_file, 0,
 					src_inode->i_size, 0);
-
+	if (rc > 0)
+		rc = 0;
 out_fput:
 	fdput(src_file);
 out_drop_write:
-- 
2.9.3