+
+static inline const char *get_device_path(struct discover_device *dev)
+{
+ return dev->ramdisk ? dev->ramdisk->snapshot : dev->device_path;
+}
+
+static char *check_subvols(struct discover_device *dev)
+{
+ const char *fstype = discover_device_get_param(dev, "ID_FS_TYPE");
+ struct stat sb;
+ char *path;
+ int rc;
+
+ if (strncmp(fstype, "btrfs", strlen("btrfs")))
+ return dev->mount_path;
+
+ /* On btrfs a device's root may be under a subvolume path */
+ path = join_paths(dev, dev->mount_path, "@");
+ rc = stat(path, &sb);
+ if (!rc && S_ISDIR(sb.st_mode)) {
+ pb_debug("Using '%s' for btrfs root path\n", path);
+ return path;
+ }
+
+ talloc_free(path);
+ return dev->mount_path;
+}
+
+static bool check_existing_mount(struct discover_device *dev)
+{
+ struct stat devstat, mntstat;
+ const char *device_path;
+ struct mntent *mnt;
+ FILE *fp;
+ int rc;
+
+ device_path = get_device_path(dev);
+
+ rc = stat(device_path, &devstat);
+ if (rc) {
+ pb_debug("%s: stat failed: %s\n", __func__, strerror(errno));
+ return false;
+ }
+
+ if (!S_ISBLK(devstat.st_mode)) {
+ pb_debug("%s: %s isn't a block device?\n", __func__,
+ dev->device_path);
+ return false;
+ }
+
+ fp = fopen("/proc/self/mounts", "r");
+
+ for (;;) {
+ mnt = getmntent(fp);
+ if (!mnt)
+ break;
+
+ if (!mnt->mnt_fsname || mnt->mnt_fsname[0] != '/')
+ continue;
+
+ rc = stat(mnt->mnt_fsname, &mntstat);
+ if (rc)
+ continue;
+
+ if (!S_ISBLK(mntstat.st_mode))
+ continue;
+
+ if (mntstat.st_rdev == devstat.st_rdev) {
+ dev->mount_path = talloc_strdup(dev, mnt->mnt_dir);
+ dev->root_path = check_subvols(dev);
+ dev->mounted_rw = !!hasmntopt(mnt, "rw");
+ dev->mounted = true;
+ dev->unmount = false;
+
+ pb_debug("%s: %s is already mounted (r%c) at %s\n",
+ __func__, dev->device_path,
+ dev->mounted_rw ? 'w' : 'o',
+ mnt->mnt_dir);
+ break;
+ }
+ }
+
+ fclose(fp);
+
+ return mnt != NULL;
+}
+
+/*
+ * Attempt to mount a filesystem safely, while handling certain filesytem-
+ * specific options
+ */
+static int try_mount(const char *device_path, const char *mount_path,
+ const char *fstype, unsigned long flags,
+ bool have_snapshot)
+{
+ const char *fs, *safe_opts;
+ int rc;
+
+ /* Mount ext3 as ext4 instead so 'norecovery' can be used */
+ if (strncmp(fstype, "ext3", strlen("ext3")) == 0) {
+ pb_debug("Mounting ext3 filesystem as ext4\n");
+ fs = "ext4";
+ } else
+ fs = fstype;
+
+ if (strncmp(fs, "xfs", strlen("xfs")) == 0 ||
+ strncmp(fs, "ext4", strlen("ext4")) == 0)
+ safe_opts = "norecovery";
+ else
+ safe_opts = NULL;
+
+ errno = 0;
+ /* If no snapshot is available don't attempt recovery */
+ if (!have_snapshot)
+ return mount(device_path, mount_path, fs, flags, safe_opts);
+
+ rc = mount(device_path, mount_path, fs, flags, NULL);
+
+ if (!rc)
+ return rc;
+
+ /* Mounting failed; some filesystems will fail to mount if a recovery
+ * journal exists (eg. cross-endian XFS), so try again with norecovery
+ * where that option is available.
+ * If mounting read-write just return the error as norecovery is not a
+ * valid option */
+ if ((flags & MS_RDONLY) != MS_RDONLY || !safe_opts)
+ return rc;
+
+ errno = 0;
+ return mount(device_path, mount_path, fs, flags, safe_opts);
+}
+
+static int mount_device(struct discover_device *dev)
+{
+ const char *fstype, *device_path;
+ int rc;
+
+ if (!dev->device_path)
+ return -1;
+
+ if (dev->mounted)
+ return 0;
+
+ if (check_existing_mount(dev))
+ return 0;
+
+ fstype = discover_device_get_param(dev, "ID_FS_TYPE");
+ if (!fstype)
+ return 0;
+
+ dev->mount_path = join_paths(dev, mount_base(),
+ dev->device_path);
+
+ if (pb_mkdir_recursive(dev->mount_path)) {
+ pb_log("couldn't create mount directory %s: %s\n",
+ dev->mount_path, strerror(errno));
+ goto err_free;
+ }
+
+ device_path = get_device_path(dev);
+
+ pb_log("mounting device %s read-only\n", dev->device_path);
+ rc = try_mount(device_path, dev->mount_path, fstype,
+ MS_RDONLY | MS_SILENT, dev->ramdisk);
+
+ if (!rc) {
+ dev->mounted = true;
+ dev->mounted_rw = false;
+ dev->unmount = true;
+ dev->root_path = check_subvols(dev);
+ return 0;
+ }
+
+ pb_log("couldn't mount device %s: mount failed: %s\n",
+ device_path, strerror(errno));
+
+ /* If mount fails clean up any snapshot */
+ devmapper_destroy_snapshot(dev);
+
+ pb_rmdir_recursive(mount_base(), dev->mount_path);
+err_free:
+ talloc_free(dev->mount_path);
+ dev->mount_path = NULL;
+ return -1;
+}
+
+static int umount_device(struct discover_device *dev)
+{
+ const char *device_path;
+ int rc;
+
+ if (!dev->mounted || !dev->unmount)
+ return 0;
+
+ device_path = get_device_path(dev);
+
+ pb_log("unmounting device %s\n", device_path);
+ rc = umount(dev->mount_path);
+ if (rc)
+ return -1;
+
+ dev->mounted = false;
+ devmapper_destroy_snapshot(dev);
+
+ pb_rmdir_recursive(mount_base(), dev->mount_path);
+
+ talloc_free(dev->mount_path);
+ dev->mount_path = NULL;
+ dev->root_path = NULL;
+
+ return 0;
+}
+
+int device_request_write(struct discover_device *dev, bool *release)
+{
+ const char *fstype, *device_path;
+ const struct config *config;
+ int rc;
+
+ *release = false;
+
+ config = config_get();
+ if (!config->allow_writes)
+ return -1;
+
+ if (!dev->mounted)
+ return -1;
+
+ if (dev->mounted_rw)
+ return 0;
+
+ fstype = discover_device_get_param(dev, "ID_FS_TYPE");
+
+ device_path = get_device_path(dev);
+
+ pb_log("remounting device %s read-write\n", device_path);
+
+ rc = umount(dev->mount_path);
+ if (rc) {
+ pb_log("Failed to unmount %s: %s\n",
+ dev->mount_path, strerror(errno));
+ return -1;
+ }
+
+ rc = try_mount(device_path, dev->mount_path, fstype,
+ MS_SILENT, dev->ramdisk);
+ if (rc)
+ goto mount_ro;
+
+ dev->mounted_rw = true;
+ *release = true;
+ return 0;
+
+mount_ro:
+ pb_log("Unable to remount device %s read-write: %s\n",
+ device_path, strerror(errno));
+ rc = try_mount(device_path, dev->mount_path, fstype,
+ MS_RDONLY | MS_SILENT, dev->ramdisk);
+ if (rc)
+ pb_log("Unable to recover mount for %s: %s\n",
+ device_path, strerror(errno));
+ return -1;
+}
+
+void device_release_write(struct discover_device *dev, bool release)
+{
+ const char *fstype, *device_path;
+
+ if (!release)
+ return;
+
+ device_path = get_device_path(dev);
+
+ fstype = discover_device_get_param(dev, "ID_FS_TYPE");
+
+ pb_log("remounting device %s read-only\n", device_path);
+
+ if (umount(dev->mount_path)) {
+ pb_log("Failed to unmount %s\n", dev->mount_path);
+ return;
+ }
+ dev->mounted_rw = dev->mounted = false;
+
+ if (dev->ramdisk) {
+ devmapper_merge_snapshot(dev);
+ /* device_path becomes stale after merge */
+ device_path = get_device_path(dev);
+ }
+
+ if (try_mount(device_path, dev->mount_path, fstype,
+ MS_RDONLY | MS_SILENT, dev->ramdisk))
+ pb_log("Failed to remount %s read-only: %s\n",
+ device_path, strerror(errno));
+ else
+ dev->mounted = true;
+}
+
+#else
+
+static void device_handler_update_lang(const char *lang __attribute__((unused)))
+{
+}
+
+static int device_handler_init_sources(
+ struct device_handler *handler __attribute__((unused)))
+{
+ return 0;
+}
+
+static void device_handler_reinit_sources(
+ struct device_handler *handler __attribute__((unused)))
+{
+}
+
+static int umount_device(struct discover_device *dev __attribute__((unused)))
+{
+ return 0;
+}
+
+static int __attribute__((unused)) mount_device(
+ struct discover_device *dev __attribute__((unused)))
+{
+ return 0;
+}
+
+int device_request_write(struct discover_device *dev __attribute__((unused)),
+ bool *release)
+{
+ *release = true;
+ return 0;
+}
+
+void device_release_write(struct discover_device *dev __attribute__((unused)),
+ bool release __attribute__((unused)))
+{
+}
+
+#endif
+