fsnotify/fdinfo: use named constants instead of hardcoded values

MAX_HANDLE_SZ is equal to 128, but currently the size of pad is only 64
bytes, so exportfs_encode_inode_fh can return an error.

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/notify/fdinfo.c

@@ -42,15 +42,15 @@ static int show_mark_fhandle(struct seq_file *m, struct inode *inode)
 {
 	struct {
 		struct file_handle handle;
-		u8 pad[64];
+		u8 pad[MAX_HANDLE_SZ];
 	} f;
 	int size, ret, i;
 
 	f.handle.handle_bytes = sizeof(f.pad);
 	size = f.handle.handle_bytes >> 2;
 
 	ret = exportfs_encode_inode_fh(inode, (struct fid *)f.handle.f_handle, &size, 0);
-	if ((ret == 255) || (ret == -ENOSPC)) {
+	if ((ret == FILEID_INVALID) || (ret == -ENOSPC)) {
 		WARN_ONCE(1, "Can't encode file handler for inotify: %d\n", ret);
 		return 0;
 	}