[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, 4 insertions, 2 deletions

diff --git a/fs/qnx4/inode.c b/fs/qnx4/inode.c
index e6cca5cd4b44..2f24c46f72a1 100644
--- a/fs/qnx4/inode.c
+++ b/fs/qnx4/inode.c
@@ -128,7 +128,7 @@ static struct inode *qnx4_alloc_inode(struct super_block *sb);
 static void qnx4_destroy_inode(struct inode *inode);
 static void qnx4_read_inode(struct inode *);
 static int qnx4_remount(struct super_block *sb, int *flags, char *data);
-static int qnx4_statfs(struct super_block *, struct kstatfs *);
+static int qnx4_statfs(struct dentry *, struct kstatfs *);
 
 static struct super_operations qnx4_sops =
 {
@@ -282,8 +282,10 @@ unsigned long qnx4_block_map( struct inode *inode, long iblock )
         return block;
 }
 
-static int qnx4_statfs(struct super_block *sb, struct kstatfs *buf)
+static int qnx4_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
+        struct super_block *sb = dentry->d_sb;
+
         lock_kernel();
 
         buf->f_type    = sb->s_magic;