posix_fadvise succeeds on FIFO.

[Valentine Barshak <vbarshak@ru.mvista.com>]

Hello all.
The following issue has been found with posix_fadvise:
the system call succeeds on a pipe or FIFO, although it has to fail with 
EINVAL return value on linux.
I've attached a small test for posix_fadvise and a patch for linux 
kernel 2.6.14 that fixes the problem.
The patch makes posix_fadvise return ESPIPE on FIFO/pipe in order to be 
fully POSIX-compliant.
Please, take a look at these. Is it really a bug in kernel?
Thanks.

#define _GNU_SOURCE
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <errno.h>

int main()
{
	int retval, fd;

	if (mkfifo("fifo", 0666) < 0) {
		printf("create fifo error\n");
		return 1;
	}
	
	fd = open("fifo", O_RDWR);
	if (fd < 0) {
		printf("open fifo error\n");
		remove("fifo");
		return 1;
	}
	
	retval = posix_fadvise(fd, 0, 0, POSIX_FADV_NORMAL);
	if (retval) {
		printf("Expected fail - The fd argument is associated with a pipe or FIFO.\n");
		if (retval != ESPIPE)
			printf("Unexpected ERRNO %d (Expected %d)\n", retval, ESPIPE);
	} else
		printf("Unexpected success  - The fd argument is associated with a pipe or FIFO.\n");

	close(fd);
	remove("fifo");

	if (retval)
		return 0;
	return 1;
}

--- a/mm/fadvise.c 2005-10-10 22:54:29.000000000 +0400
+++ b/mm/fadvise.c 2005-12-06 23:04:19.980711464 +0300
@@ -37,6 +37,11 @@
        if (!file)
                return -EBADF;
 
+       if (S_ISFIFO(file->f_dentry->d_inode->i_mode)) {
+               ret = -ESPIPE;
+               goto out;
+       }
+
        mapping = file->f_mapping;
        if (!mapping || len < 0) {
                ret = -EINVAL;