From f9f99573d74dc8c002871d6f54adcdcdba251d45 Mon Sep 17 00:00:00 2001
From: Tycho Andersen <tycho.andersen@canonical.com>
Date: Thu, 9 Apr 2015 20:32:00 +0300
Subject: [PATCH] mnt: relax constraints on fuse mounts

1. If a fuse connection is present, but there are no fuse mounts of that type
   in the mount namespace, don't refuse to dump.
2. If there are mounts of that type in the container but they are external,
   we're going to bind them anyway, so there's no fuse-specific things that
   need to be done, so it is safe to dump.

v2: check that the fstype is fuse as well

Signed-off-by: Tycho Andersen <tycho.andersen@canonical.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
---
 mount.c            | 57 +++++++++++++++++++++++++++++++++++++++++++++-
 protobuf/mnt.proto |  1 +
 2 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/mount.c b/mount.c
index 15d571684..04ff8af05 100644
--- a/mount.c
+++ b/mount.c
@@ -1024,6 +1024,47 @@ out:
 	return ret;
 }
 
+static int fusectl_dump(struct mount_info *pm)
+{
+	int fd, ret = -1;
+	struct dirent *de;
+	DIR *fdir = NULL;
+
+	fd = open_mountpoint(pm);
+	if (fd < 0)
+		return -1;
+
+	fdir = fdopendir(fd);
+	if (fdir == NULL) {
+		close(fd);
+		return -1;
+	}
+
+	while ((de = readdir(fdir))) {
+		int id;
+		struct mount_info *it;
+
+		if (dir_dots(de))
+			continue;
+
+		if (sscanf(de->d_name, "%d", &id) != 1) {
+			pr_err("wrong number of items scanned in fusectl dump\n");
+			goto out;
+		}
+
+		for (it = mntinfo; it; it = it->next) {
+			if (it->fstype->code == FSTYPE__FUSE && id == minor(it->s_dev) && !it->external) {
+				pr_err("%s is a fuse mount but not external\n", it->mountpoint);
+				goto out;
+			}
+		}
+	}
+
+	ret = 0;
+out:
+	closedir(fdir);
+	return ret;
+}
 
 static int dump_empty_fs(struct mount_info *pm)
 {
@@ -1055,6 +1096,15 @@ out:
 	return ret;
 }
 
+/*
+ * Some fses (fuse) cannot be dumped, so we should always fail on dump/restore
+ * of these fses.
+ */
+static int always_fail(struct mount_info *pm)
+{
+	return -1;
+}
+
 static struct fstype fstypes[] = {
 	{
 		.name = "unsupported",
@@ -1102,7 +1152,7 @@ static struct fstype fstypes[] = {
 		.code = FSTYPE__SECURITYFS,
 	}, {
 		.name = "fusectl",
-		.dump = dump_empty_fs,
+		.dump = fusectl_dump,
 		.code = FSTYPE__FUSECTL,
 	}, {
 		.name = "debugfs",
@@ -1114,6 +1164,11 @@ static struct fstype fstypes[] = {
 		.name = "aufs",
 		.code = FSTYPE__AUFS,
 		.parse = aufs_parse,
+	}, {
+		.name = "fuse",
+		.code = FSTYPE__FUSE,
+		.dump = always_fail,
+		.restore = always_fail,
 	},
 };
 
diff --git a/protobuf/mnt.proto b/protobuf/mnt.proto
index 343bd6dd7..d0cd5dafb 100644
--- a/protobuf/mnt.proto
+++ b/protobuf/mnt.proto
@@ -16,6 +16,7 @@ enum fstype {
 	CGROUP			= 12;
 	AUFS			= 13;
 	MQUEUE			= 14;
+	FUSE			= 15;
 };
 
 message mnt_entry {