CIFS: fiemap: do not return EINVAL if get nothing

If we call fiemap on a truncated file with none blocks allocated,
it makes sense we get nothing from this call. No output means
no blocks have been counted, but the call succeeded. It's a valid
response.

Simple example reproducer:
xfs_io -f 'truncate 2M' -c 'fiemap -v' /cifssch/testfile
xfs_io: ioctl(FS_IOC_FIEMAP) ["/cifssch/testfile"]: Invalid argument

Signed-off-by: Murphy Zhou <jencce.kernel@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
CC: Stable <stable@vger.kernel.org>

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 3dddd20c5e2bd17aff56d4cac1fb12d830c86bcc..cfe9b800ea8c2e45ec5eff688a4da5ee181f694f 100644 (file)
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -3419,7 +3419,7 @@ static int smb3_fiemap(struct cifs_tcon *tcon,
        if (rc)
                goto out;
 
-       if (out_data_len < sizeof(struct file_allocated_range_buffer)) {
+       if (out_data_len && out_data_len < sizeof(struct file_allocated_range_buffer)) {
                rc = -EINVAL;
                goto out;
        }