[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/befs/linuxvfs.c b/fs/befs/linuxvfs.c
index 6ed07a5f10c6..08201fab26cd 100644
--- a/fs/befs/linuxvfs.c
+++ b/fs/befs/linuxvfs.c
@@ -49,7 +49,7 @@ static int befs_nls2utf(struct super_block *sb, const char *in, int in_len,
                         char **out, int *out_len);
 static void befs_put_super(struct super_block *);
 static int befs_remount(struct super_block *, int *, char *);
-static int befs_statfs(struct super_block *, struct kstatfs *);
+static int befs_statfs(struct dentry *, struct kstatfs *);
 static int parse_options(char *, befs_mount_options *);
 
 static const struct super_operations befs_sops = {
@@ -880,8 +880,9 @@ befs_remount(struct super_block *sb, int *flags, char *data)
 }
 
 static int
-befs_statfs(struct super_block *sb, struct kstatfs *buf)
+befs_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
+        struct super_block *sb = dentry->d_sb;
 
         befs_debug(sb, "---> befs_statfs()");