CIFS: fiemap: do not return EINVAL if get nothing

commit a0c902f92c84e6bb072373b4fe43b25c90012c7f upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 99420608d2ec510a72ad84f45ca82828edb0f271..76eacffb24d86e1061ef6541644f00cf3f694a43 100644 (file)
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -3252,7 +3252,7 @@ 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;
        }