saner calling conventions for unlazy_child()

same as for the previous commit - instead of 0/-ECHILD make
it return true/false, rename to try_to_unlazy_child().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namei.c

@@ -705,19 +705,19 @@ static bool try_to_unlazy(struct nameidata *nd)
 }
 
 /**
- * unlazy_child - try to switch to ref-walk mode.
+ * try_to_unlazy_next - try to switch to ref-walk mode.
  * @nd: nameidata pathwalk data
- * @dentry: child of nd->path.dentry
- * @seq: seq number to check dentry against
- * Returns: 0 on success, -ECHILD on failure
+ * @dentry: next dentry to step into
+ * @seq: seq number to check @dentry against
+ * Returns: true on success, false on failure
  *
- * unlazy_child attempts to legitimize the current nd->path, nd->root and dentry
- * for ref-walk mode.  @dentry must be a path found by a do_lookup call on
- * @nd.  Must be called from rcu-walk context.
- * Nothing should touch nameidata between unlazy_child() failure and
+ * Similar to to try_to_unlazy(), but here we have the next dentry already
+ * picked by rcu-walk and want to legitimize that in addition to the current
+ * nd->path and nd->root for ref-walk mode.  Must be called from rcu-walk context.
+ * Nothing should touch nameidata between try_to_unlazy_next() failure and
  * terminate_walk().
  */
-static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned seq)
+static bool try_to_unlazy_next(struct nameidata *nd, struct dentry *dentry, unsigned seq)
 {
 	BUG_ON(!(nd->flags & LOOKUP_RCU));
 
@@ -747,7 +747,7 @@ static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned se
 	if (unlikely(!legitimize_root(nd)))
 		goto out_dput;
 	rcu_read_unlock();
-	return 0;
+	return true;
 
 out2:
 	nd->path.mnt = NULL;
@@ -755,11 +755,11 @@ static int unlazy_child(struct nameidata *nd, struct dentry *dentry, unsigned se
 	nd->path.dentry = NULL;
 out:
 	rcu_read_unlock();
-	return -ECHILD;
+	return false;
 out_dput:
 	rcu_read_unlock();
 	dput(dentry);
-	return -ECHILD;
+	return false;
 }
 
 static inline int d_revalidate(struct dentry *dentry, unsigned int flags)
@@ -1372,7 +1372,7 @@ static inline int handle_mounts(struct nameidata *nd, struct dentry *dentry,
 			return -ENOENT;
 		if (likely(__follow_mount_rcu(nd, path, inode, seqp)))
 			return 0;
-		if (unlazy_child(nd, dentry, seq))
+		if (!try_to_unlazy_next(nd, dentry, seq))
 			return -ECHILD;
 		// *path might've been clobbered by __follow_mount_rcu()
 		path->mnt = nd->path.mnt;
@@ -1493,7 +1493,7 @@ static struct dentry *lookup_fast(struct nameidata *nd,
 		status = d_revalidate(dentry, nd->flags);
 		if (likely(status > 0))
 			return dentry;
-		if (unlazy_child(nd, dentry, seq))
+		if (!try_to_unlazy_next(nd, dentry, seq))
 			return ERR_PTR(-ECHILD);
 		if (status == -ECHILD)
 			/* we'd been told to redo it in non-rcu mode */