fs/9p: don't set SB_NOATIME by default

When the user uses some syscall, for example mmap(v9fs_file_mmap), it
will not update atime even if user's was set mnt_flags without
MNT_NOATIME, because v9fs defaults to settine SB_NOATIME in
v9fs_set_super.

For supporting access time updating when the user mounts with relatime,
we should not set SB_NOATIME by default.

Link: http://lkml.kernel.org/r/5AB9A377.6080906@huawei.comSigned-off-by: NYiwen Jiang <jiangyiwen@huawei.com>
Reviewed-by: NGreg Kurz <groug@kaod.org>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Cc: Ron Minnich <rminnich@sandia.gov>
Cc: Latchesar Ionkov <lucho@ionkov.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fs/9p/vfs_super.c

@@ -94,7 +94,7 @@ v9fs_fill_super(struct super_block *sb, struct v9fs_session_info *v9ses,
 	if (v9ses->cache)
 		sb->s_bdi->ra_pages = (VM_MAX_READAHEAD * 1024)/PAGE_SIZE;
 
-	sb->s_flags |= SB_ACTIVE | SB_DIRSYNC | SB_NOATIME;
+	sb->s_flags |= SB_ACTIVE | SB_DIRSYNC;
 	if (!v9ses->cache)
 		sb->s_flags |= SB_SYNCHRONOUS;