[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, 4 deletions

diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index c1ce284f8a94..7c35d582ec10 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -539,18 +539,18 @@ static int fat_remount(struct super_block *sb, int *flags, char *data)
         return 0;
 }
 
-static int fat_statfs(struct super_block *sb, struct kstatfs *buf)
+static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
-        struct msdos_sb_info *sbi = MSDOS_SB(sb);
+        struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
 
         /* If the count of free cluster is still unknown, counts it here. */
         if (sbi->free_clusters == -1) {
-                int err = fat_count_free_clusters(sb);
+                int err = fat_count_free_clusters(dentry->d_sb);
                 if (err)
                         return err;
         }
 
-        buf->f_type = sb->s_magic;
+        buf->f_type = dentry->d_sb->s_magic;
         buf->f_bsize = sbi->cluster_size;
         buf->f_blocks = sbi->max_cluster - FAT_START_ENT;
         buf->f_bfree = sbi->free_clusters;