kernfs: move revalidate to be near lookup

While the dentry operation kernfs_dop_revalidate() is grouped with
dentry type functions it also has a strong affinity to the inode
operation ->lookup().

It makes sense to locate this function near to kernfs_iop_lookup()
because we will be adding VFS negative dentry caching to reduce path
lookup overhead for non-existent paths.

There's no functional change from this patch.

Signed-off-by: Ian Kent <raven@themaw.net>
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Link: https://lore.kernel.org/r/162375275365.232295.8995526416263659926.stgit@web.messagingengine.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/kernfs/dir.c

@@ -548,49 +548,6 @@ void kernfs_put(struct kernfs_node *kn)
 }
 EXPORT_SYMBOL_GPL(kernfs_put);
 
-static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
-{
-	struct kernfs_node *kn;
-
-	if (flags & LOOKUP_RCU)
-		return -ECHILD;
-
-	/* Always perform fresh lookup for negatives */
-	if (d_really_is_negative(dentry))
-		goto out_bad_unlocked;
-
-	kn = kernfs_dentry_node(dentry);
-	mutex_lock(&kernfs_mutex);
-
-	/* The kernfs node has been deactivated */
-	if (!kernfs_active(kn))
-		goto out_bad;
-
-	/* The kernfs node has been moved? */
-	if (kernfs_dentry_node(dentry->d_parent) != kn->parent)
-		goto out_bad;
-
-	/* The kernfs node has been renamed */
-	if (strcmp(dentry->d_name.name, kn->name) != 0)
-		goto out_bad;
-
-	/* The kernfs node has been moved to a different namespace */
-	if (kn->parent && kernfs_ns_enabled(kn->parent) &&
-	    kernfs_info(dentry->d_sb)->ns != kn->ns)
-		goto out_bad;
-
-	mutex_unlock(&kernfs_mutex);
-	return 1;
-out_bad:
-	mutex_unlock(&kernfs_mutex);
-out_bad_unlocked:
-	return 0;
-}
-
-const struct dentry_operations kernfs_dops = {
-	.d_revalidate	= kernfs_dop_revalidate,
-};
-
 /**
  * kernfs_node_from_dentry - determine kernfs_node associated with a dentry
  * @dentry: the dentry in question
@@ -1073,6 +1030,49 @@ struct kernfs_node *kernfs_create_empty_dir(struct kernfs_node *parent,
 	return ERR_PTR(rc);
 }
 
+static int kernfs_dop_revalidate(struct dentry *dentry, unsigned int flags)
+{
+	struct kernfs_node *kn;
+
+	if (flags & LOOKUP_RCU)
+		return -ECHILD;
+
+	/* Always perform fresh lookup for negatives */
+	if (d_really_is_negative(dentry))
+		goto out_bad_unlocked;
+
+	kn = kernfs_dentry_node(dentry);
+	mutex_lock(&kernfs_mutex);
+
+	/* The kernfs node has been deactivated */
+	if (!kernfs_active(kn))
+		goto out_bad;
+
+	/* The kernfs node has been moved? */
+	if (kernfs_dentry_node(dentry->d_parent) != kn->parent)
+		goto out_bad;
+
+	/* The kernfs node has been renamed */
+	if (strcmp(dentry->d_name.name, kn->name) != 0)
+		goto out_bad;
+
+	/* The kernfs node has been moved to a different namespace */
+	if (kn->parent && kernfs_ns_enabled(kn->parent) &&
+	    kernfs_info(dentry->d_sb)->ns != kn->ns)
+		goto out_bad;
+
+	mutex_unlock(&kernfs_mutex);
+	return 1;
+out_bad:
+	mutex_unlock(&kernfs_mutex);
+out_bad_unlocked:
+	return 0;
+}
+
+const struct dentry_operations kernfs_dops = {
+	.d_revalidate	= kernfs_dop_revalidate,
+};
+
 static struct dentry *kernfs_iop_lookup(struct inode *dir,
 					struct dentry *dentry,
 					unsigned int flags)