[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, 2 insertions, 2 deletions

diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c
index 04035e08f5c1..8e0d37743e7c 100644
--- a/fs/hostfs/hostfs_kern.c
+++ b/fs/hostfs/hostfs_kern.c
@@ -239,7 +239,7 @@ static int read_inode(struct inode *ino)
         return(err);
 }
 
-int hostfs_statfs(struct super_block *sb, struct kstatfs *sf)
+int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
 {
         /* do_statfs uses struct statfs64 internally, but the linux kernel
          * struct statfs still has 32-bit versions for most of these fields,
@@ -252,7 +252,7 @@ int hostfs_statfs(struct super_block *sb, struct kstatfs *sf)
         long long f_files;
         long long f_ffree;
 
-        err = do_statfs(HOSTFS_I(sb->s_root->d_inode)->host_filename,
+        err = do_statfs(HOSTFS_I(dentry->d_sb->s_root->d_inode)->host_filename,
                         &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
                         &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
                         &sf->f_namelen, sf->f_spare);