[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>

1 files changed, 3 insertions, 2 deletions

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index ff645a961bc8..937fbfc381bb 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -65,7 +65,7 @@ static int nfs_write_inode(struct inode *,int);
 static void nfs_delete_inode(struct inode *);
 static void nfs_clear_inode(struct inode *);
 static void nfs_umount_begin(struct super_block *);
-static int  nfs_statfs(struct super_block *, struct kstatfs *);
+static int  nfs_statfs(struct dentry *, struct kstatfs *);
 static int  nfs_show_options(struct seq_file *, struct vfsmount *);
 static int  nfs_show_stats(struct seq_file *, struct vfsmount *);
 static void nfs_zap_acl_cache(struct inode *);
@@ -534,8 +534,9 @@ nfs_fill_super(struct super_block *sb, struct nfs_mount_data *data, int silent)
 }
 
 static int
-nfs_statfs(struct super_block *sb, struct kstatfs *buf)
+nfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
+        struct super_block *sb = dentry->d_sb;
         struct nfs_server *server = NFS_SB(sb);
         unsigned char blockbits;
         unsigned long blockres;