pass a struct path to vfs_statfs

We'll need the path to implement the flags field for statvfs support.
We do have it available in all callers except:

 - ecryptfs_statfs.  This one doesn't actually need vfs_statfs but just
   needs to do a caller to the lower filesystem statfs method.
 - sys_ustat.  Add a non-exported statfs_by_dentry helper for it which
   doesn't won't be able to fill out the flags field later on.

In addition rename the helpers for statfs vs fstatfs to do_*statfs instead
of the misleading vfs prefix.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/alpha/kernel/osf_sys.c b/arch/alpha/kernel/osf_sys.c
index de9d397..88131c6 100644
--- a/arch/alpha/kernel/osf_sys.c
+++ b/arch/alpha/kernel/osf_sys.c
@@ -234,11 +234,11 @@
 }
 
 static int
-do_osf_statfs(struct dentry * dentry, struct osf_statfs __user *buffer,
+do_osf_statfs(struct path *path, struct osf_statfs __user *buffer,
 	      unsigned long bufsiz)
 {
 	struct kstatfs linux_stat;
-	int error = vfs_statfs(dentry, &linux_stat);
+	int error = vfs_statfs(path, &linux_stat);
 	if (!error)
 		error = linux_to_osf_statfs(&linux_stat, buffer, bufsiz);
 	return error;	
@@ -252,7 +252,7 @@
 
 	retval = user_path(pathname, &path);
 	if (!retval) {
-		retval = do_osf_statfs(path.dentry, buffer, bufsiz);
+		retval = do_osf_statfs(&path buffer, bufsiz);
 		path_put(&path);
 	}
 	return retval;
@@ -267,7 +267,7 @@
 	retval = -EBADF;
 	file = fget(fd);
 	if (file) {
-		retval = do_osf_statfs(file->f_path.dentry, buffer, bufsiz);
+		retval = do_osf_statfs(&file->f_path, buffer, bufsiz);
 		fput(file);
 	}
 	return retval;