[CRIU] [PATCH 3/4] mount: handle mnt_flags and sb_flags separatly

[Andrey Vagin]

They both can container the MS_READONLY flag. And in one case it will be
read-only bind-mount and in another case it will be read-only
super-block.

Signed-off-by: Andrey Vagin <avagin at openvz.org>
---
 include/proc_parse.h |  1 +
 mount.c              | 27 +++++++++++++++++++--------
 proc_parse.c         |  2 +-
 protobuf/mnt.proto   |  2 ++
 4 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/include/proc_parse.h b/include/proc_parse.h
index 42f8893..ed68c95 100644
--- a/include/proc_parse.h
+++ b/include/proc_parse.h
@@ -118,6 +118,7 @@ struct mount_info {
 	char		*mountpoint;
 	char		*ns_mountpoint;
 	unsigned	flags;
+	unsigned	sb_flags;
 	int		master_id;
 	int		shared_id;
 	struct fstype	*fstype;
diff --git a/mount.c b/mount.c
index 344d646..4589399 100644
--- a/mount.c
+++ b/mount.c
@@ -1598,6 +1598,8 @@ static int dump_one_mountpoint(struct mount_info *pm, struct cr_img *img)
 	me.root_dev		= pm->s_dev;
 	me.parent_mnt_id	= pm->parent_mnt_id;
 	me.flags		= pm->flags;
+	me.sb_flags		= pm->sb_flags;
+	me.has_sb_flags		= true;
 	me.mountpoint		= pm->mountpoint + 1;
 	me.source		= pm->source;
 	me.options		= pm->options;
@@ -1806,14 +1808,22 @@ static char *resolve_source(struct mount_info *mi)
 
 static int restore_shared_options(struct mount_info *mi, bool private, bool shared, bool slave)
 {
+	unsigned int mflags = MS_SHARED | MS_SLAVE | MS_PRIVATE;
+
 	pr_debug("%d:%s private %d shared %d slave %d\n",
 			mi->mnt_id, mi->mountpoint, private, shared, slave);
 
-	if (mi->flags & MS_UNBINDABLE) {
-		if (shared || slave)
-			pr_warn("%s has both unbindable and sharing, ignoring unbindable\n", mi->mountpoint);
-		else
-			return mount(NULL, mi->mountpoint, NULL, MS_UNBINDABLE, NULL);
+
+	mflags = mi->flags & (~mflags);
+
+	if ((mi->flags & MS_UNBINDABLE) && (shared || slave)) {
+		pr_warn("%s has both unbindable and sharing, ignoring unbindable\n", mi->mountpoint);
+		mflags &= ~MS_UNBINDABLE;
+	}
+
+	if (mount(NULL, mi->mountpoint, NULL, MS_REMOUNT | MS_BIND | mflags, NULL)) {
+		pr_perror("Unable to restore mount flags: %x\n", mi->flags);
+		return -1;
 	}
 
 	if (private && mount(NULL, mi->mountpoint, NULL, MS_PRIVATE, NULL)) {
@@ -1935,10 +1945,10 @@ skip_parent:
 
 static int do_new_mount(struct mount_info *mi)
 {
-	unsigned long mflags = MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE;
+	unsigned long mflags = 0;
 	char *src;
 	struct fstype *tp = mi->fstype;
-	bool remount_ro = (tp->restore && mi->flags & MS_RDONLY);
+	bool remount_ro = (tp->restore && mi->sb_flags & MS_RDONLY);
 
 	src = resolve_source(mi);
 	if (!src)
@@ -1948,7 +1958,7 @@ static int do_new_mount(struct mount_info *mi)
 		mflags |= MS_RDONLY;
 
 	if (mount(src, mi->mountpoint, tp->name,
-			mi->flags & ~mflags, mi->options) < 0) {
+			mi->sb_flags & ~mflags, mi->options) < 0) {
 		pr_perror("Can't mount at %s", mi->mountpoint);
 		return -1;
 	}
@@ -2324,6 +2334,7 @@ static int collect_mnt_from_image(struct mount_info **pms, struct ns_id *nsid)
 		pm->parent_mnt_id	= me->parent_mnt_id;
 		pm->s_dev		= me->root_dev;
 		pm->flags		= me->flags;
+		pm->sb_flags		= me->sb_flags;
 		pm->shared_id		= me->shared_id;
 		pm->master_id		= me->master_id;
 		pm->need_plugin		= me->with_plugin;
diff --git a/proc_parse.c b/proc_parse.c
index 1f58f7f..10fb2df 100644
--- a/proc_parse.c
+++ b/proc_parse.c
@@ -1078,7 +1078,7 @@ static int parse_mountinfo_ent(char *str, struct mount_info *new, char **fsname)
 	if (!new->options)
 		goto err;
 
-	if (parse_sb_opt(opt, &new->flags, new->options))
+	if (parse_sb_opt(opt, &new->sb_flags, new->options))
 		goto err;
 
 	ret = 0;
diff --git a/protobuf/mnt.proto b/protobuf/mnt.proto
index 6e58e1d..c6a1787 100644
--- a/protobuf/mnt.proto
+++ b/protobuf/mnt.proto
@@ -41,4 +41,6 @@ message mnt_entry {
 
 	optional string		fsname			= 14;
 	optional bool		internal_sharing	= 15;
+
+	optional uint32		sb_flags		= 16 [(criu).hex = true];
 }
-- 
2.1.0