add f_flags to struct statfs(64)

Add a flags field to help glibc implementing statvfs(3) efficiently.

We copy the flag values from glibc, and add a new ST_VALID flag to
denote that f_flags is implemented.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/asm-generic/statfs.h b/include/asm-generic/statfs.h
index 3b4fb3e..0fd28e0 100644
--- a/include/asm-generic/statfs.h
+++ b/include/asm-generic/statfs.h
@@ -33,7 +33,8 @@
 	__kernel_fsid_t f_fsid;
 	__statfs_word f_namelen;
 	__statfs_word f_frsize;
-	__statfs_word f_spare[5];
+	__statfs_word f_flags;
+	__statfs_word f_spare[4];
 };
 
 /*
@@ -55,7 +56,8 @@
 	__kernel_fsid_t f_fsid;
 	__statfs_word f_namelen;
 	__statfs_word f_frsize;
-	__statfs_word f_spare[5];
+	__statfs_word f_flags;
+	__statfs_word f_spare[4];
 } ARCH_PACK_STATFS64;
 
 /* 
@@ -77,7 +79,8 @@
 	__kernel_fsid_t f_fsid;
 	__u32 f_namelen;
 	__u32 f_frsize;
-	__u32 f_spare[5];
+	__u32 f_flags;
+	__u32 f_spare[4];
 } ARCH_PACK_COMPAT_STATFS64;
 
 #endif