From bdd198cd917643f92e3b7bec7146eb3f51fec92b Mon Sep 17 00:00:00 2001
From: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Date: Mon, 29 Jun 2020 18:04:41 +0300
Subject: [PATCH 185/245] mount: move root yard tree merge as early as possible

Let's merge mount trees under root_yard just after reading from image.

Cherry-picked from Virtuozzo criu:
https://src.openvz.org/projects/OVZ/repos/criu/commits/8e8ecdfdc

Changes: split only root yard part as a separate patch, and put root
yard alloc into merge_mount_trees.

Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
---
 criu/mount.c | 68 ++++++++++++++++++++++++++--------------------------
 1 file changed, 34 insertions(+), 34 deletions(-)

diff --git a/criu/mount.c b/criu/mount.c
index 30872f1ce..b2810b7a5 100644
--- a/criu/mount.c
+++ b/criu/mount.c
@@ -3271,6 +3271,37 @@ err:
 	return -1;
 }
 
+static int merge_mount_trees(void)
+{
+	struct ns_id *nsid;
+
+	root_yard_mp = mnt_entry_alloc(true);
+	if (!root_yard_mp)
+		return -1;
+
+	root_yard_mp->mountpoint = mnt_roots;
+	root_yard_mp->mounted = true;
+	root_yard_mp->mnt_bind_is_populated = true;
+	root_yard_mp->is_overmounted = false;
+	root_yard_mp->mnt_id = HELPER_MNT_ID;
+
+	/* Merge mount trees together under root_yard_mp */
+	for (nsid = ns_ids; nsid; nsid = nsid->next) {
+		struct mount_info *root;
+
+		if (nsid->nd != &mnt_ns_desc)
+			continue;
+
+		root = nsid->mnt.mntinfo_tree;
+
+		pr_debug("Mountpoint %d (@%s) moved to the root yard\n", root->mnt_id, root->mountpoint);
+		root->parent = root_yard_mp;
+		list_add(&root->siblings, &root_yard_mp->children);
+	}
+
+	return 0;
+}
+
 int read_mnt_ns_img(void)
 {
 	struct mount_info *pms = NULL;
@@ -3303,6 +3334,9 @@ int read_mnt_ns_img(void)
 	search_bindmounts();
 	prepare_is_overmounted();
 
+	if (merge_mount_trees())
+		return -1;
+
 	return 0;
 }
 
@@ -3401,27 +3435,6 @@ void fini_restore_mntns(void)
 	}
 }
 
-static int merge_mount_trees(struct mount_info *root_yard)
-{
-	struct ns_id *nsid;
-
-	/* Merge mount trees together under root_yard */
-	for (nsid = ns_ids; nsid; nsid = nsid->next) {
-		struct mount_info *root;
-
-		if (nsid->nd != &mnt_ns_desc)
-			continue;
-
-		root = nsid->mnt.mntinfo_tree;
-
-		pr_debug("Mountpoint %d (@%s) moved to the root yard\n", root->mnt_id, root->mountpoint);
-		root->parent = root_yard;
-		list_add(&root->siblings, &root_yard->children);
-	}
-
-	return 0;
-}
-
 /*
  * All nested mount namespaces are restore as sub-trees of the root namespace.
  */
@@ -3469,19 +3482,6 @@ static int populate_mnt_ns(void)
 	struct mount_info *cr_time = NULL;
 	int ret;
 
-	root_yard_mp = mnt_entry_alloc(true);
-	if (!root_yard_mp)
-		return -1;
-
-	root_yard_mp->mountpoint = mnt_roots;
-	root_yard_mp->mounted = true;
-	root_yard_mp->mnt_bind_is_populated = true;
-	root_yard_mp->is_overmounted = false;
-	root_yard_mp->mnt_id = HELPER_MNT_ID;
-
-	if (merge_mount_trees(root_yard_mp))
-		return -1;
-
 #ifdef CONFIG_BINFMT_MISC_VIRTUALIZED
 	if (!opts.has_binfmt_misc && !list_empty(&binfmt_misc_list)) {
 		/* Add to mount tree. Generic code will mount it later */
-- 
2.35.1