[patch 2/5] samples/vfs: avoid warning in statx override

[Andrew Morton <akpm@linux-foundation.org>]

From: Kees Cook <keescook@chromium.org>
Subject: samples/vfs: avoid warning in statx override

Something changed recently to uncover this warning:

samples/vfs/test-statx.c:24:15: warning: `struct foo' declared inside parameter list will not be visible outside of this definition or declaration
   24 | #define statx foo
      |               ^~~

Which is due the use of "struct statx" (here, "struct foo") in a function
prototype argument list before it has been defined:

 int
 # 56 "/usr/include/x86_64-linux-gnu/bits/statx-generic.h"
    foo
 # 56 "/usr/include/x86_64-linux-gnu/bits/statx-generic.h" 3 4
          (int __dirfd, const char *__restrict __path, int __flags,
            unsigned int __mask, struct
 # 57 "/usr/include/x86_64-linux-gnu/bits/statx-generic.h"
                                       foo
 # 57 "/usr/include/x86_64-linux-gnu/bits/statx-generic.h" 3 4
                                             *__restrict __buf)
   __attribute__ ((__nothrow__ , __leaf__)) __attribute__ ((__nonnull__ (2, 5)));

Add explicit struct before #include to avoid warning.

Link: http://lkml.kernel.org/r/202006282213.C516EA6@keescook
Fixes: f1b5618e013a ("vfs: Add a sample program for the new mount API")
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Miklos Szeredi <mszeredi@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 samples/vfs/test-statx.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/samples/vfs/test-statx.c~samples-vfs-avoid-warning-in-statx-override
+++ a/samples/vfs/test-statx.c
@@ -23,6 +23,8 @@
 #include <linux/fcntl.h>
 #define statx foo
 #define statx_timestamp foo_timestamp
+struct statx;
+struct statx_timestamp;
 #include <sys/stat.h>
 #undef statx
 #undef statx_timestamp
_