[CRIU] [PATCH] mount: Add ability to restore ro tmpfs

[Cyrill Gorcunov]

In case if we've dumped read only tmpfs
we fail restoring it because it's mounted
with ro flags. Lets mount it with rw,
restore content and then remount as ro.

Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
---
 mount.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/mount.c b/mount.c
index e45b8b29866e..db5e8f19d6f7 100644
--- a/mount.c
+++ b/mount.c
@@ -1843,20 +1843,22 @@ skip_parent:
 	return 0;
 }
 
-#define MS_CHANGE_TYPE_MASK	\
-	(MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)
-
 static int do_new_mount(struct mount_info *mi)
 {
+	unsigned long mflags = MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE;
 	char *src;
 	struct fstype *tp = mi->fstype;
+	bool remount_ro = (tp->code == FSTYPE__TMPFS && mi->flags & MS_RDONLY);
 
 	src = resolve_source(mi);
 	if (!src)
 		return -1;
 
+	if (remount_ro)
+		mflags |= MS_RDONLY;
+
 	if (mount(src, mi->mountpoint, tp->name,
-			mi->flags & ~MS_CHANGE_TYPE_MASK, mi->options) < 0) {
+			mi->flags & ~mflags, mi->options) < 0) {
 		pr_perror("Can't mount at %s", mi->mountpoint);
 		return -1;
 	}
@@ -1871,6 +1873,9 @@ static int do_new_mount(struct mount_info *mi)
 	if (tp->restore && tp->restore(mi))
 		return -1;
 
+	if (remount_ro)
+		return mount(NULL, mi->mountpoint, tp->name,
+			     MS_REMOUNT | MS_RDONLY, NULL);
 	return 0;
 }
 
-- 
2.1.0