[PATCH] VFS: Permit filesystem to perform statfs with a known root dentry

Give the statfs superblock operation a dentry pointer rather than a superblock
pointer.

This complements the get_sb() patch.  That reduced the significance of
sb->s_root, allowing NFS to place a fake root there.  However, NFS does
require a dentry to use as a target for the statfs operation.  This permits
the root in the vfsmount to be used instead.

linux/mount.h has been added where necessary to make allyesconfig build
successfully.

Interest has also been expressed for use with the FUSE and XFS filesystems.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nathan Scott <nathans@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/jffs2/fs.c b/fs/jffs2/fs.c
index 7b6c24b..2900ec3 100644
--- a/fs/jffs2/fs.c
+++ b/fs/jffs2/fs.c
@@ -192,9 +192,9 @@
 	return rc;
 }
 
-int jffs2_statfs(struct super_block *sb, struct kstatfs *buf)
+int jffs2_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
-	struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);
+	struct jffs2_sb_info *c = JFFS2_SB_INFO(dentry->d_sb);
 	unsigned long avail;
 
 	buf->f_type = JFFS2_SUPER_MAGIC;