mount: Turn into --external

Make --external support --ext-mount-map. The syntax is

 --ext-mount-map KEY:VAL == --external mnt[KEY]:VAL

Old option is kept for backward compatibility.

travis-ci: success for mnt: Deprecate --ext-mount-map for --external
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/crtools.c

@@ -827,10 +827,12 @@ usage:
 "                            file[mnt_id:inode]\n"
 "                            dev[maj:min]:VAL\n"
 "                            unix[ino]\n"
+"                            mnt[MOUNTPOINT]:COOKIE\n"
 "                        Formats of RES on restore:\n"
 "                            dev[VAL]:DEVPATH\n"
 "                            veth[IFNAME]:OUTNAME{@BRIDGE}\n"
 "                            macvlan[IFNAME]:OUTNAME\n"
+"                            mnt[COOKIE]:ROOT\n"
 "\n"
 "* Special resources support:\n"
 "     --" SK_EST_PARAM "  checkpoint/restore established TCP connections\n"
@@ -847,8 +849,6 @@ usage:
 "  --force-irmap         force resolving names for inotify/fsnotify watches\n"
 "  --irmap-scan-path FILE\n"
 "                        add a path the irmap hints to scan\n"
-"  -M|--ext-mount-map KEY:VALUE\n"
-"                        add external mount mapping\n"
 "  -M|--ext-mount-map auto\n"
 "                        attempt to autodetect external mount mappings\n"
 "  --enable-external-sharing\n"

criu/include/mount.h

@@ -10,24 +10,6 @@ struct pstree_item;
 struct fstype;
 struct ns_id;
 
-/*
- * Structure to keep external mount points resolving info.
- *
- * On dump the key is the mountpoint as seen from the mount
- * namespace, the val is some name that will be put into image
- * instead of the mount point's root path.
- *
- * On restore the key is the name from the image (the one
- * mentioned above) and the val is the path in criu's mount
- * namespace that will become the mount point's root, i.e. --
- * be bind mounted to the respective mountpoint.
- */
-struct ext_mount {
-	struct list_head	list;
-	char			*key;
-	char			*val;
-};
-
 #define MOUNT_INVALID_DEV	(0)
 
 struct mount_info {

criu/mount.c

@@ -45,29 +45,40 @@
 
 int ext_mount_add(char *key, char *val)
 {
-	struct ext_mount *em;
+	char *e_str;
 
-	em = xmalloc(sizeof(*em));
-	if (!em)
+	e_str = xmalloc(strlen(key) + strlen(val) + 8);
+	if (!e_str)
 		return -1;
 
-	em->key = key;
-	em->val = val;
-	list_add_tail(&em->list, &opts.ext_mounts);
-	pr_info("Added %s:%s ext mount mapping\n", key, val);
-	return 0;
+	/*
+	 * On dump the key is the mountpoint as seen from the mount
+	 * namespace, the val is some name that will be put into image
+	 * instead of the mount point's root path.
+	 *
+	 * On restore the key is the name from the image (the one
+	 * mentioned above) and the val is the path in criu's mount
+	 * namespace that will become the mount point's root, i.e. --
+	 * be bind mounted to the respective mountpoint.
+	 */
+
+	sprintf(e_str, "mnt[%s]:%s", key, val);
+	return add_external(e_str);
 }
 
 /* Lookup ext_mount by key field */
 static char *ext_mount_lookup(char *key)
 {
-	struct ext_mount *em;
+	char *v;
+	int len = strlen(key);
+	char mkey[len + 8];
 
-	list_for_each_entry(em, &opts.ext_mounts, list)
-		if (!strcmp(em->key, key))
-			return em->val;
+	sprintf(mkey, "mnt[%s]", key);
+	v = external_lookup_by_key(mkey);
+	if (IS_ERR(v))
+		v = NULL;
 
-	return NULL;
+	return v;
 }
 
 /*