[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/ext2/super.c b/fs/ext2/super.c
index a4dfffac5967..a6c4d6e02324 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -39,7 +39,7 @@
 static void ext2_sync_super(struct super_block *sb,
                             struct ext2_super_block *es);
 static int ext2_remount (struct super_block * sb, int * flags, char * data);
-static int ext2_statfs (struct super_block * sb, struct kstatfs * buf);
+static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf);
 
 void ext2_error (struct super_block * sb, const char * function,
                  const char * fmt, ...)
@@ -1038,8 +1038,9 @@ restore_opts:
         return err;
 }
 
-static int ext2_statfs (struct super_block * sb, struct kstatfs * buf)
+static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
 {
+        struct super_block *sb = dentry->d_sb;
         struct ext2_sb_info *sbi = EXT2_SB(sb);
         unsigned long overhead;
         int i;