inotify: Sort marks by wd before collecting them

The inotify_add_watch generates wd-s one-by one. We cannot
request for one, thus we call this syscall till the required
wd is generated.

Thus, if we want to restore several wd-s for an inotify, we
have to put them in ascending order. Otherwise we may restore
watch with higher wd earlier and will thus not be able to
generate the lower wd in a reasonable time.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

fsnotify.c

@@ -417,20 +417,38 @@ static struct file_desc_ops fanotify_desc_ops = {
 	.open = open_fanotify_fd,
 };
 
+static struct fsnotify_file_info *find_inotify_info(unsigned id)
+{
+	struct fsnotify_file_info *p;
+
+	list_for_each_entry(p, &inotify_info_head, list)
+		if (p->ife->id == id)
+			return p;
+
+	pr_err("Can't find inotify with id 0x%08x\n", id);
+	return NULL;
+}
+
 static int collect_inotify_mark(struct fsnotify_mark_info *mark)
 {
 	struct fsnotify_file_info *p;
+	struct fsnotify_mark_info *m;
 
-	list_for_each_entry(p, &inotify_info_head, list) {
-		if (p->ife->id == mark->iwe->id) {
-			list_add(&mark->list, &p->marks);
+	p = find_inotify_info(mark->iwe->id);
+	if (!p)
+		return -1;
+
+	/*
+	 * We should put marks in wd ascending order. See comment
+	 * in restore_one_inotify() for explanation.
+	 */
+	list_for_each_entry(m, &p->marks, list)
+		if (m->iwe->wd > mark->iwe->wd)
+			break;
+
+	list_add_tail(&mark->list, &m->list);
 	mark->remap = lookup_ghost_remap(mark->iwe->s_dev, mark->iwe->i_ino);
 	return 0;
-		}
-	}
-
-	pr_err("Can't find inotify with id 0x%08x\n", mark->iwe->id);
-	return -1;
 }
 
 static int collect_fanotify_mark(struct fsnotify_mark_info *mark)