[CRIU] [PATCH 06/16] restore: collect vma-s before creating children (v2)

[Andrey Vagin]

A private vma's should be inherited by children for
restoring copy-on-write regions.

v2: free parent's vma-s in this patch.

Signed-off-by: Andrey Vagin <avagin at openvz.org>
---
 cr-restore.c | 53 +++++++++++++++++++++++++++++++++--------------------
 1 file changed, 33 insertions(+), 20 deletions(-)

diff --git a/cr-restore.c b/cr-restore.c
index 276cf49..87f5e26 100644
--- a/cr-restore.c
+++ b/cr-restore.c
@@ -62,9 +62,12 @@
 static struct pstree_item *current;
 
 static int restore_task_with_children(void *);
-static int sigreturn_restore(pid_t pid, CoreEntry *core, struct list_head *vmas, int nr_vmas);
+static int sigreturn_restore(pid_t pid, CoreEntry *core);
 static int prepare_restorer_blob(void);
 
+static LIST_HEAD(rst_vma_list);
+static int rst_nr_vmas;
+
 static int shmem_remap(void *old_addr, void *new_addr, unsigned long size)
 {
 	void *ret;
@@ -176,17 +179,21 @@ err:
 	return ret;
 }
 
-static int read_vmas(int pid, struct list_head *vmas, int *nr_vmas)
+static int read_vmas(int pid)
 {
-	int fd, ret = -1;
+	int fd, ret = 0;
+	LIST_HEAD(old);
+	struct vma_area *vma;
+
+	list_replace_init(&rst_vma_list, &old);
 
+	/* Skip errors, because a zombie doesn't have an image of vmas */
 	fd = open_image_ro(CR_FD_VMAS, pid);
 	if (fd < 0)
-		return fd;
+		goto out;
 
-	*nr_vmas = 0;
+	rst_nr_vmas = 0;
 	while (1) {
-		struct vma_area *vma;
 		VmaEntry *e;
 
 		ret = -1;
@@ -198,8 +205,8 @@ static int read_vmas(int pid, struct list_head *vmas, int *nr_vmas)
 		if (ret <= 0)
 			break;
 
-		(*nr_vmas)++;
-		list_add_tail(&vma->list, vmas);
+		rst_nr_vmas++;
+		list_add_tail(&vma->list, &rst_vma_list);
 
 		if (e->fd != -1) {
 			ret = -1;
@@ -213,6 +220,14 @@ static int read_vmas(int pid, struct list_head *vmas, int *nr_vmas)
 	}
 
 	close(fd);
+
+out:
+	while (!list_empty(&old)) {
+		vma = list_first_entry(&old, struct vma_area, list);
+		list_del(&vma->list);
+		xfree(vma);
+	}
+
 	return ret;
 }
 
@@ -255,18 +270,13 @@ static int open_vmas(int pid, struct list_head *vmas)
 
 static int prepare_and_sigreturn(int pid, CoreEntry *core)
 {
-	int err, nr_vmas;
-	LIST_HEAD(vma_list);
+	int err;
 
-	err = read_vmas(pid, &vma_list, &nr_vmas);
+	err = open_vmas(pid, &rst_vma_list);
 	if (err)
 		return err;
 
-	err = open_vmas(pid, &vma_list);
-	if (err)
-		return err;
-
-	return sigreturn_restore(pid, core, &vma_list, nr_vmas);
+	return sigreturn_restore(pid, core);
 }
 
 static rt_sigaction_t sigchld_act;
@@ -851,6 +861,9 @@ static int restore_task_with_children(void *_arg)
 		exit(1);
 	}
 
+	if (read_vmas(pid))
+		exit(1);
+
 	pr_info("Restoring children:\n");
 	list_for_each_entry(child, &current->children, sibling) {
 		if (!restore_before_setsid(child))
@@ -1362,7 +1375,7 @@ static int prep_sched_info(struct rst_sched_param *sp, ThreadCoreEntry *tc)
 	return 0;
 }
 
-static int sigreturn_restore(pid_t pid, CoreEntry *core, struct list_head *tgt_vmas, int nr_vmas)
+static int sigreturn_restore(pid_t pid, CoreEntry *core)
 {
 	long restore_task_vma_len;
 	long restore_thread_vma_len, self_vmas_len, vmas_len;
@@ -1396,7 +1409,7 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core, struct list_head *tgt_v
 	mark_stack_vma((long) &self_vma_list, &self_vma_list);
 
 	self_vmas_len = round_up((ret + 1) * sizeof(VmaEntry), PAGE_SIZE);
-	vmas_len = round_up((nr_vmas + 1) * sizeof(VmaEntry), PAGE_SIZE);
+	vmas_len = round_up((rst_nr_vmas + 1) * sizeof(VmaEntry), PAGE_SIZE);
 
 	/* pr_info_vma_list(&self_vma_list); */
 
@@ -1424,7 +1437,7 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core, struct list_head *tgt_v
 				SHMEMS_SIZE + TASK_ENTRIES_SIZE +
 				self_vmas_len + vmas_len +
 				rst_tcp_socks_size;
-	exec_mem_hint = restorer_get_vma_hint(pid, tgt_vmas, &self_vma_list,
+	exec_mem_hint = restorer_get_vma_hint(pid, &rst_vma_list, &self_vma_list,
 					      restore_bootstrap_len);
 	if (exec_mem_hint == -1) {
 		pr_err("No suitable area for task_restore bootstrap (%ldK)\n",
@@ -1497,7 +1510,7 @@ static int sigreturn_restore(pid_t pid, CoreEntry *core, struct list_head *tgt_v
 		goto err;
 
 	mem += self_vmas_len;
-	task_args->tgt_vmas = vma_list_remap(mem, vmas_len, tgt_vmas);
+	task_args->tgt_vmas = vma_list_remap(mem, vmas_len, &rst_vma_list);
 	if (!task_args->tgt_vmas)
 		goto err;
 
-- 
1.7.11.7