X-Git-Url: http://git.archive.openwrt.org/?p=project%2Ffstools.git;a=blobdiff_plain;f=libfstools%2Fmount.c;h=e095455eebe702c513833c5860c1768fec8f2133;hp=efcfcd8bcf15283a958e83f2cf3caa0e072af316;hb=1a57eb9b7cc5e772d1090a23c51fdd4a01ec5df0;hpb=9303a84fb4bcf84ebcf58f2afdd7cac7dde0161f

diff --git a/libfstools/mount.c b/libfstools/mount.c
index efcfcd8..e095455 100644
--- a/libfstools/mount.c
+++ b/libfstools/mount.c
@@ -90,11 +90,45 @@ fopivot(char *rw_root, char *ro_root)
 	}
 
 	snprintf(overlay, sizeof(overlay), "overlayfs:%s", rw_root);
-	snprintf(lowerdir, sizeof(lowerdir), "lowerdir=/,upperdir=%s", rw_root);
 
+	/*
+	 * First, try to mount without a workdir, for overlayfs v22 and before.
+	 * If it fails, it means that we are probably using a v23 and
+	 * later versions that require a workdir
+	 */
+	snprintf(lowerdir, sizeof(lowerdir), "lowerdir=/,upperdir=%s", rw_root);
 	if (mount(overlay, "/mnt", "overlayfs", MS_NOATIME, lowerdir)) {
-		fprintf(stderr, "mount failed: %s\n", strerror(errno));
-		return -1;
+		char upperdir[64], workdir[64], upgrade[64], upgrade_dest[64];
+		struct stat st;
+
+		snprintf(upperdir, sizeof(upperdir), "%s/upper", rw_root);
+		snprintf(workdir, sizeof(workdir), "%s/work", rw_root);
+		snprintf(upgrade, sizeof(upgrade), "%s/sysupgrade.tgz", rw_root);
+		snprintf(upgrade_dest, sizeof(upgrade_dest), "%s/sysupgrade.tgz", upperdir);
+		snprintf(lowerdir, sizeof(lowerdir), "lowerdir=/,upperdir=%s,workdir=%s",
+			 upperdir, workdir);
+
+		/*
+		 * Overlay FS v23 and later requires both a upper and
+		 * a work directory, both on the same filesystem, but
+		 * not part of the same subtree.
+		 * We can't really deal with these constraints without
+		 * creating two new subdirectories in /overlay.
+		 */
+		mkdir(upperdir, 0755);
+		mkdir(workdir, 0755);
+
+		if (stat(upgrade, &st) == 0)
+		    rename(upgrade, upgrade_dest);
+
+		/* Mainlined overlayfs has been renamed to "overlay", try that first */
+		if (mount(overlay, "/mnt", "overlay", MS_NOATIME, lowerdir)) {
+			if (mount(overlay, "/mnt", "overlayfs", MS_NOATIME, lowerdir)) {
+				fprintf(stderr, "mount failed: %s, options %s\n",
+					strerror(errno), lowerdir);
+				return -1;
+			}
+		}
 	}
 
 	return pivot("/mnt", ro_root);