[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, 3 deletions

diff --git a/fs/ntfs/super.c b/fs/ntfs/super.c
index d5d5e969294f..0e14acea3f8b 100644
--- a/fs/ntfs/super.c
+++ b/fs/ntfs/super.c
@@ -2601,10 +2601,10 @@ static unsigned long __get_nr_free_mft_records(ntfs_volume *vol,
 
 /**
  * ntfs_statfs - return information about mounted NTFS volume
- * @sb:         super block of mounted volume
+ * @dentry:     dentry from mounted volume
  * @sfs:        statfs structure in which to return the information
  *
- * Return information about the mounted NTFS volume @sb in the statfs structure
+ * Return information about the mounted NTFS volume @dentry in the statfs structure
  * pointed to by @sfs (this is initialized with zeros before ntfs_statfs is
  * called). We interpret the values to be correct of the moment in time at
  * which we are called. Most values are variable otherwise and this isn't just
@@ -2617,8 +2617,9 @@ static unsigned long __get_nr_free_mft_records(ntfs_volume *vol,
  *
  * Return 0 on success or -errno on error.
  */
-static int ntfs_statfs(struct super_block *sb, struct kstatfs *sfs)
+static int ntfs_statfs(struct dentry *dentry, struct kstatfs *sfs)
 {
+        struct super_block *sb = dentry->d_sb;
         s64 size;
         ntfs_volume *vol = NTFS_SB(sb);
         ntfs_inode *mft_ni = NTFS_I(vol->mft_ino);