overlay: fix race condition when switching to jffs2

[project/fstools.git] / libfstools / overlay.c

diff --git a/libfstools/overlay.c b/libfstools/overlay.c
index cdac23e..8423a57 100644 (file)
--- a/libfstools/overlay.c
+++ b/libfstools/overlay.c
@@ -102,16 +102,16 @@ static int
 overlay_mount(struct volume *v, char *fs)
 {
        if (mkdir("/tmp/overlay", 0755)) {
-               ULOG_ERR("failed to mkdir /tmp/overlay: %s\n", strerror(errno));
+               ULOG_ERR("failed to mkdir /tmp/overlay: %m\n");
                return -1;
        }
 
        if (mount(v->blk, "/tmp/overlay", fs, MS_NOATIME, NULL)) {
-               ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %s\n", fs, v->blk, strerror(errno));
+               ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %m\n", fs, v->blk);
                return -1;
        }
 
-       return volume_init(v);
+       return 0;
 }
 
 static int
@@ -129,27 +129,27 @@ switch2jffs(struct volume *v)
        ret = mount(v->blk, "/rom/overlay", "jffs2", MS_NOATIME, NULL);
        unlink("/tmp/.switch_jffs2");
        if (ret) {
-               ULOG_ERR("failed - mount -t jffs2 %s /rom/overlay: %s\n", v->blk, strerror(errno));
+               ULOG_ERR("failed - mount -t jffs2 %s /rom/overlay: %m\n", v->blk);
                return -1;
        }
 
        if (mount("none", "/", NULL, MS_NOATIME | MS_REMOUNT, 0)) {
-               ULOG_ERR("failed - mount -o remount,ro none: %s\n", strerror(errno));
+               ULOG_ERR("failed - mount -o remount,ro none: %m\n");
                return -1;
        }
 
        if (system("cp -a /tmp/root/* /rom/overlay")) {
-               ULOG_ERR("failed - cp -a /tmp/root/* /rom/overlay: %s\n", strerror(errno));
+               ULOG_ERR("failed - cp -a /tmp/root/* /rom/overlay: %m\n");
                return -1;
        }
 
        if (pivot("/rom", "/mnt")) {
-               ULOG_ERR("failed - pivot /rom /mnt: %s\n", strerror(errno));
+               ULOG_ERR("failed - pivot /rom /mnt: %m\n");
                return -1;
        }
 
        if (mount_move("/mnt", "/tmp/root", "")) {
-               ULOG_ERR("failed - mount -o move /mnt /tmp/root %s\n", strerror(errno));
+               ULOG_ERR("failed - mount -o move /mnt /tmp/root %m\n");
                return -1;
        }
 
@@ -192,64 +192,75 @@ handle_whiteout(const char *dir)
        return 0;
 }
 
+static char *overlay_fs_name(int type)
+{
+       switch (type) {
+               case FS_EXT4:
+                       return "ext4";
+               case FS_F2FS:
+                       return "f2fs";
+               case FS_UBIFS:
+                       return "ubifs";
+               case FS_JFFS2:
+               default:
+                       return "jffs2";
+       }
+}
+
 int
 jffs2_switch(struct volume *v)
 {
-       char *mp;
-       int ret = -1;
+       char *mp, *fs_name;
+       int type;
 
        if (find_overlay_mount("overlayfs:/tmp/root"))
                return -1;
 
        if (find_filesystem("overlay")) {
                ULOG_ERR("overlayfs not supported by kernel\n");
-               return ret;
+               return -1;
        }
 
+       volume_init(v);
        mp = find_mount_point(v->blk, 0);
        if (mp) {
                ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk, mp);
                return -1;
        }
 
-       switch (volume_identify(v)) {
+       type = volume_identify(v);
+       fs_name = overlay_fs_name(type);
+
+       switch (type) {
        case FS_NONE:
                ULOG_ERR("no jffs2 marker found\n");
                /* fall through */
 
        case FS_DEADCODE:
-               ret = switch2jffs(v);
-               if (!ret) {
-                       ULOG_INFO("performing overlay whiteout\n");
-                       umount2("/tmp/root", MNT_DETACH);
-                       foreachdir("/overlay/", handle_whiteout);
-               }
-               break;
+               if (switch2jffs(v))
+                       return -1;
 
-       case FS_JFFS2:
-               ret = overlay_mount(v, "jffs2");
-               if (ret)
-                       break;
-               if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
-                       ULOG_ERR("switching to jffs2 failed\n");
-                       ret = -1;
-               }
+               ULOG_INFO("performing overlay whiteout\n");
+               umount2("/tmp/root", MNT_DETACH);
+               foreachdir("/overlay/", handle_whiteout);
+
+               /* try hard to be in sync */
+               ULOG_INFO("syncronizing overlay\n");
+               system("cp -a /tmp/root/upper/* / 2>/dev/null");
                break;
 
+       case FS_EXT4:
+       case FS_F2FS:
        case FS_UBIFS:
-               ret = overlay_mount(v, "ubifs");
-               if (ret)
-                       break;
+               if (overlay_mount(v, fs_name))
+                       return -1;
                if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
-                       ULOG_ERR("switching to ubifs failed\n");
-                       ret = -1;
+                       ULOG_ERR("switching to %s failed\n", fs_name);
+                       return -1;
                }
                break;
        }
 
-       if (ret)
-               return ret;
-
        sync();
        fs_state_set("/overlay", FS_STATE_READY);
        return 0;
@@ -257,30 +268,20 @@ jffs2_switch(struct volume *v)
 
 static int overlay_mount_fs(struct volume *v)
 {
-       char *fstype;
+       char *fstype = overlay_fs_name(volume_identify(v));
 
        if (mkdir("/tmp/overlay", 0755)) {
-               ULOG_ERR("failed to mkdir /tmp/overlay: %s\n", strerror(errno));
+               ULOG_ERR("failed to mkdir /tmp/overlay: %m\n");
                return -1;
        }
 
-       fstype = "jffs2";
-
-       switch (volume_identify(v)) {
-       case FS_UBIFS:
-               fstype = "ubifs";
-               break;
-       }
-
-       volume_init(v);
-
        if (mount(v->blk, "/tmp/overlay", fstype, MS_NOATIME, NULL)) {
-               ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %s\n",
-                        fstype, v->blk, strerror(errno));
+               ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %m\n",
+                        fstype, v->blk);
                return -1;
        }
 
-       return -1;
+       return 0;
 }
 
 enum fs_state fs_state_get(const char *dir)
@@ -325,7 +326,7 @@ int fs_state_set(const char *dir, enum fs_state state)
 
 int mount_overlay(struct volume *v)
 {
-       char *mp;
+       char *mp, *fs_name;
 
        if (!v)
                return -1;
@@ -359,9 +360,10 @@ int mount_overlay(struct volume *v)
                break;
        }
 
-       ULOG_INFO("switching to jffs2 overlay\n");
+       fs_name = overlay_fs_name(volume_identify(v));
+       ULOG_INFO("switching to %s overlay\n", fs_name);
        if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
-               ULOG_ERR("switching to jffs2 failed - fallback to ramoverlay\n");
+               ULOG_ERR("switching to %s failed - fallback to ramoverlay\n", fs_name);
                return ramoverlay();
        }