[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/affs/super.c b/fs/affs/super.c
index 6a52e787540..8765cba35bb 100644
--- a/fs/affs/super.c
+++ b/fs/affs/super.c
@@ -18,7 +18,7 @@
 
 extern struct timezone sys_tz;
 
-static int affs_statfs(struct super_block *sb, struct kstatfs *buf);
+static int affs_statfs(struct dentry *dentry, struct kstatfs *buf);
 static int affs_remount (struct super_block *sb, int *flags, char *data);
 
 static void
@@ -508,8 +508,9 @@ affs_remount(struct super_block *sb, int *flags, char *data)
 }
 
 static int
-affs_statfs(struct super_block *sb, struct kstatfs *buf)
+affs_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
+        struct super_block *sb = dentry->d_sb;
         int              free;
 
         pr_debug("AFFS: statfs() partsize=%d, reserved=%d\n",AFFS_SB(sb)->s_partition_size,