bdev: use correct overlay module name

- Assume that the module name is "overlay" per default and not "overlayfs".
- Assume that the overlay version we are using requires a workdir.
- When we mount an overlay filesystem and we fail with ENODEV retry once with
  the module name we haven't already used.

Signed-off-by: Christian Brauner <cbrauner@suse.de>

diff --git a/src/lxc/bdev/lxcoverlay.c b/src/lxc/bdev/lxcoverlay.c
index 3caadbc4afe9753e78cb66036743431e136e3a89..e8d0f6d30baca2491d884d41774d99485dc3af26 100644 (file)
--- a/src/lxc/bdev/lxcoverlay.c
+++ b/src/lxc/bdev/lxcoverlay.c
@@ -39,6 +39,7 @@
 lxc_log_define(lxcoverlay, lxc);
 
 static char *ovl_name;
+static char *ovl_version[] = {"overlay", "overlayfs"};
 
 /* defined in lxccontainer.c: needs to become common helper */
 extern char *dir_new_path(char *src, const char *oldname, const char *name,
@@ -49,6 +50,9 @@ static int ovl_do_rsync(struct bdev *orig, struct bdev *new,
                        struct lxc_conf *conf);
 static int ovl_rsync(struct rsync_data *data);
 static int ovl_rsync_wrapper(void *data);
+static int ovl_remount_on_enodev(const char *lower, const char *target,
+                                const char *name, unsigned long mountflags,
+                                const void *options);
 
 int ovl_clonepaths(struct bdev *orig, struct bdev *new, const char *oldname,
                   const char *cname, const char *oldpath, const char *lxcpath,
@@ -408,23 +412,28 @@ int ovl_mount(struct bdev *bdev)
                return -1;
        }
 
-       // mount without workdir option for overlayfs before v21
-       ret = mount(lower, bdev->dest, ovl_name, MS_MGC_VAL | mntflags, options);
+        /* Assume we need a workdir as we are on a overlay version >= v22. */
+       ret = ovl_remount_on_enodev(lower, bdev->dest, ovl_name,
+                                   MS_MGC_VAL | mntflags, options_work);
        if (ret < 0) {
-               INFO("overlayfs: error mounting %s onto %s options %s. retry with workdir",
-                       lower, bdev->dest, options);
+               INFO("Overlayfs: Error mounting %s onto %s with options %s. "
+                    "Retrying without workdir: %s.",
+                    lower, bdev->dest, options_work, strerror(errno));
 
-               // retry with workdir option for overlayfs v22 and higher
-               ret = mount(lower, bdev->dest, ovl_name, MS_MGC_VAL | mntflags, options_work);
+                /* Assume we cannot use a workdir as we are on a version <= v21. */
+               ret = ovl_remount_on_enodev(lower, bdev->dest, ovl_name,
+                                         MS_MGC_VAL | mntflags, options);
                if (ret < 0)
-                       SYSERROR("overlayfs: error mounting %s onto %s options %s",
-                               lower, bdev->dest, options_work);
+                       SYSERROR("Overlayfs: Error mounting %s onto %s with "
+                                "options %s: %s.",
+                                lower, bdev->dest, options,
+                                strerror(errno));
                else
-                       INFO("overlayfs: mounted %s onto %s options %s",
-                               lower, bdev->dest, options_work);
+                       INFO("Overlayfs: Mounted %s onto %s with options %s.",
+                            lower, bdev->dest, options);
        } else {
-               INFO("overlayfs: mounted %s onto %s options %s",
-                       lower, bdev->dest, options);
+               INFO("Overlayfs: Mounted %s onto %s with options %s.", lower,
+                    bdev->dest, options_work);
        }
        return ret;
 }
@@ -652,6 +661,20 @@ err:
        return fret;
 }
 
+static int ovl_remount_on_enodev(const char *lower, const char *target,
+                                const char *name, unsigned long mountflags,
+                                const void *options)
+{
+        int ret;
+        ret = mount(lower, target, ovl_name, MS_MGC_VAL | mountflags, options);
+        if (ret < 0 && errno == ENODEV) /* Try other module name. */
+               ret = mount(lower, target,
+                           ovl_name == ovl_version[0] ? ovl_version[1]
+                                                      : ovl_version[0],
+                           MS_MGC_VAL | mountflags, options);
+        return ret;
+}
+
 static int ovl_rsync(struct rsync_data *data)
 {
        int ret;
@@ -700,7 +723,7 @@ static int ovl_rsync(struct rsync_data *data)
 
 static char *ovl_detect_name(void)
 {
-       char *v = "overlayfs";
+       char *v = ovl_version[0];
        char *line = NULL;
        size_t len = 0;
        FILE *f = fopen("/proc/filesystems", "r");
@@ -708,8 +731,8 @@ static char *ovl_detect_name(void)
                return v;
 
        while (getline(&line, &len, f) != -1) {
-               if (strcmp(line, "nodev\toverlay\n") == 0) {
-                       v = "overlay";
+               if (strcmp(line, "nodev\toverlayfs\n") == 0) {
+                       v = ovl_version[1];
                        break;
                }
        }