From: Murphy Zhou <jencce.kernel@xxxxxxxxx> commit 979a2665eb6c603ddce0ab374041ab101827b2e7 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@xxxxxxxxx> Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx> Reviewed-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx> CC: Stable <stable@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/cifs/smb2ops.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/cifs/smb2ops.c +++ b/fs/cifs/smb2ops.c @@ -3315,7 +3315,7 @@ static int smb3_fiemap(struct cifs_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; }