X-Git-Url: http://git.ozlabs.org/?p=petitboot;a=blobdiff_plain;f=discover%2Fdevice-handler.c;h=346cb0221d7f08e8b5bcbd7b72f33c596f344f8b;hp=d2b50b5e36c3e170ad478ca12bbd93e819fcef50;hb=a50d5fe279db71cf85fabeb675c99b167ec63dcb;hpb=fa5c9dfa37957d45b13424ade53d477f0b123102

diff --git a/discover/device-handler.c b/discover/device-handler.c
index d2b50b5..346cb02 100644
--- a/discover/device-handler.c
+++ b/discover/device-handler.c
@@ -26,6 +26,7 @@
 
 #include "device-handler.h"
 #include "discover-server.h"
+#include "devmapper.h"
 #include "user-event.h"
 #include "platform.h"
 #include "event.h"
@@ -56,6 +57,9 @@ struct device_handler {
 	struct discover_device	**devices;
 	unsigned int		n_devices;
 
+	struct ramdisk_device	**ramdisks;
+	unsigned int		n_ramdisks;
+
 	struct waitset		*waitset;
 	struct waiter		*timeout_waiter;
 	bool			autoboot_enabled;
@@ -319,6 +323,7 @@ struct device_handler *device_handler_init(struct discover_server *server,
 void device_handler_reinit(struct device_handler *handler)
 {
 	struct discover_boot_option *opt, *tmp;
+	struct ramdisk_device *ramdisk;
 	unsigned int i;
 
 	device_handler_cancel_default(handler);
@@ -333,12 +338,17 @@ void device_handler_reinit(struct device_handler *handler)
 	for (i = 0; i < handler->n_devices; i++) {
 		discover_server_notify_device_remove(handler->server,
 				handler->devices[i]->device);
+		ramdisk = handler->devices[i]->ramdisk;
 		talloc_free(handler->devices[i]);
+		talloc_free(ramdisk);
 	}
 
 	talloc_free(handler->devices);
 	handler->devices = NULL;
 	handler->n_devices = 0;
+	talloc_free(handler->ramdisks);
+	handler->ramdisks = NULL;
+	handler->n_ramdisks = 0;
 
 	device_handler_reinit_sources(handler);
 }
@@ -349,6 +359,15 @@ void device_handler_remove(struct device_handler *handler,
 	struct discover_boot_option *opt, *tmp;
 	unsigned int i;
 
+	list_for_each_entry_safe(&device->boot_options, opt, tmp, list) {
+		if (opt == handler->default_boot_option) {
+			pb_log("Default option %s cancelled since device removed",
+					opt->option->name);
+			device_handler_cancel_default(handler);
+			break;
+		}
+	}
+
 	for (i = 0; i < handler->n_devices; i++)
 		if (handler->devices[i] == device)
 			break;
@@ -386,7 +405,7 @@ void device_handler_remove(struct device_handler *handler,
 	talloc_free(device);
 }
 
-static void boot_status(void *arg, struct boot_status *status)
+void device_handler_boot_status(void *arg, struct boot_status *status)
 {
 	struct device_handler *handler = arg;
 
@@ -435,8 +454,11 @@ static int default_timeout(void *arg)
 
 	pb_log("Timeout expired, booting default option %s\n", opt->option->id);
 
+	platform_pre_boot();
+
 	handler->pending_boot = boot(handler, handler->default_boot_option,
-			NULL, handler->dry_run, boot_status, handler);
+			NULL, handler->dry_run, device_handler_boot_status,
+			handler);
 	handler->pending_boot_is_default = true;
 	return 0;
 }
@@ -447,6 +469,7 @@ struct {
 } device_type_map[] = {
 	{ IPMI_BOOTDEV_NETWORK, DEVICE_TYPE_NETWORK },
 	{ IPMI_BOOTDEV_DISK, DEVICE_TYPE_DISK },
+	{ IPMI_BOOTDEV_DISK, DEVICE_TYPE_USB },
 	{ IPMI_BOOTDEV_CDROM, DEVICE_TYPE_OPTICAL },
 };
 
@@ -590,6 +613,7 @@ static bool __attribute__((used)) boot_option_is_resolved(
 	return resource_is_resolved(opt->boot_image) &&
 		resource_is_resolved(opt->initrd) &&
 		resource_is_resolved(opt->dtb) &&
+		resource_is_resolved(opt->args_sig_file) &&
 		resource_is_resolved(opt->icon);
 }
 
@@ -615,6 +639,8 @@ static bool boot_option_resolve(struct discover_boot_option *opt,
 	return resource_resolve(opt->boot_image, "boot_image", opt, handler) &&
 		resource_resolve(opt->initrd, "initrd", opt, handler) &&
 		resource_resolve(opt->dtb, "dtb", opt, handler) &&
+		resource_resolve(opt->args_sig_file, "args_sig_file", opt,
+			handler) &&
 		resource_resolve(opt->icon, "icon", opt, handler);
 }
 
@@ -629,6 +655,7 @@ static void boot_option_finalise(struct device_handler *handler,
 	assert(!opt->option->dtb_file);
 	assert(!opt->option->icon_file);
 	assert(!opt->option->device_id);
+	assert(!opt->option->args_sig_file);
 
 	if (opt->boot_image)
 		opt->option->boot_image_file = opt->boot_image->url->full;
@@ -638,6 +665,8 @@ static void boot_option_finalise(struct device_handler *handler,
 		opt->option->dtb_file = opt->dtb->url->full;
 	if (opt->icon)
 		opt->option->icon_file = opt->icon->url->full;
+	if (opt->args_sig_file)
+		opt->option->args_sig_file = opt->args_sig_file->url->full;
 
 	opt->option->device_id = opt->device->device->id;
 
@@ -694,60 +723,105 @@ struct discover_context *device_handler_discover_context_create(
 	return ctx;
 }
 
-/**
- * context_commit - Commit a temporary discovery context to the handler,
- * and notify the clients about any new options / devices
- */
-void device_handler_discover_context_commit(struct device_handler *handler,
-		struct discover_context *ctx)
+void device_handler_add_device(struct device_handler *handler,
+		struct discover_device *device)
 {
-	struct discover_device *dev = ctx->device;
-	struct discover_boot_option *opt, *tmp;
+	handler->n_devices++;
+	handler->devices = talloc_realloc(handler, handler->devices,
+				struct discover_device *, handler->n_devices);
+	handler->devices[handler->n_devices - 1] = device;
 
-	if (!device_lookup_by_id(handler, dev->device->id))
-		device_handler_add_device(handler, dev);
+	if (device->device->type == DEVICE_TYPE_NETWORK)
+		network_register_device(handler->network, device);
+}
 
-	/* move boot options from the context to the device */
-	list_for_each_entry_safe(&ctx->boot_options, opt, tmp, list) {
-		list_remove(&opt->list);
+void device_handler_add_ramdisk(struct device_handler *handler,
+		const char *path)
+{
+	struct ramdisk_device *dev;
+	unsigned int i;
 
-		if (boot_option_resolve(opt, handler)) {
-			pb_log("boot option %s is resolved, "
-					"sending to clients\n",
-					opt->option->id);
-			list_add_tail(&dev->boot_options, &opt->list);
-			talloc_steal(dev, opt);
-			boot_option_finalise(handler, opt);
-			notify_boot_option(handler, opt);
+	if (!path)
+		return;
+
+	for (i = 0; i < handler->n_ramdisks; i++)
+		if (!strcmp(handler->ramdisks[i]->path, path))
+			return;
+
+	dev = talloc_zero(handler, struct ramdisk_device);
+	if (!dev) {
+		pb_log("Failed to allocate memory to track %s\n", path);
+		return;
+	}
+
+	dev->path = talloc_strdup(handler, path);
+
+	handler->ramdisks = talloc_realloc(handler, handler->ramdisks,
+				struct ramdisk_device *,
+				handler->n_ramdisks + 1);
+	if (!handler->ramdisks) {
+		pb_log("Failed to reallocate memory"
+		       "- ramdisk tracking inconsistent!\n");
+		return;
+	}
+
+	handler->ramdisks[i] = dev;
+	i = handler->n_ramdisks++;
+}
+
+struct ramdisk_device *device_handler_get_ramdisk(
+		struct device_handler *handler)
+{
+	unsigned int i;
+	char *name;
+	dev_t id;
+
+	/* Check if free ramdisk exists */
+	for (i = 0; i < handler->n_ramdisks; i++)
+		if (!handler->ramdisks[i]->snapshot &&
+		    !handler->ramdisks[i]->origin &&
+		    !handler->ramdisks[i]->base)
+			return handler->ramdisks[i];
+
+	/* Otherwise create a new one */
+	name = talloc_asprintf(handler, "/dev/ram%d",
+			handler->n_ramdisks);
+	if (!name) {
+		pb_debug("Failed to allocate memory to name /dev/ram%d",
+			handler->n_ramdisks);
+		return NULL;
+	}
+
+	id = makedev(1, handler->n_ramdisks);
+	if (mknod(name, S_IFBLK, id)) {
+		if (errno == EEXIST) {
+			/* We haven't yet received updates for existing
+			 * ramdisks - add and use this one */
+			pb_debug("Using untracked ramdisk %s\n", name);
 		} else {
-			if (!opt->source->resolve_resource) {
-				pb_log("parser %s gave us an unresolved "
-					"resource (%s), but no way to "
-					"resolve it\n",
-					opt->source->name, opt->option->id);
-				talloc_free(opt);
-			} else {
-				pb_log("boot option %s is unresolved, "
-						"adding to queue\n",
-						opt->option->id);
-				list_add(&handler->unresolved_boot_options,
-						&opt->list);
-				talloc_steal(handler, opt);
-			}
+			pb_log("Failed to create new ramdisk %s: %s\n",
+			       name, strerror(errno));
+			return NULL;
 		}
 	}
+	device_handler_add_ramdisk(handler, name);
+	talloc_free(name);
+
+	return handler->ramdisks[i];
 }
 
-void device_handler_add_device(struct device_handler *handler,
-		struct discover_device *device)
+void device_handler_release_ramdisk(struct discover_device *device)
 {
-	handler->n_devices++;
-	handler->devices = talloc_realloc(handler, handler->devices,
-				struct discover_device *, handler->n_devices);
-	handler->devices[handler->n_devices - 1] = device;
+	struct ramdisk_device *ramdisk = device->ramdisk;
 
-	if (device->device->type == DEVICE_TYPE_NETWORK)
-		network_register_device(handler->network, device);
+	talloc_free(ramdisk->snapshot);
+	talloc_free(ramdisk->origin);
+	talloc_free(ramdisk->base);
+
+	ramdisk->snapshot = ramdisk->origin = ramdisk->base = NULL;
+	ramdisk->sectors = 0;
+
+	device->ramdisk = NULL;
 }
 
 /* Start discovery on a hotplugged device. The device will be in our devices
@@ -762,10 +836,16 @@ int device_handler_discover(struct device_handler *handler,
 
 	status = talloc_zero(handler, struct boot_status);
 	status->type = BOOT_STATUS_INFO;
-	status->message = talloc_asprintf(status, "Processing %s device %s",
+	/*
+	 * TRANSLATORS: this string will be passed the type and identifier
+	 * of the device. For example, the first parameter could be "Disk",
+	 * (which will be translated accordingly) and the second a Linux device
+	 * identifier like 'sda1' (which will not be translated)
+	 */
+	status->message = talloc_asprintf(status, _("Processing %s device %s"),
 				device_type_display_name(dev->device->type),
 				dev->device->id);
-	boot_status(handler, status);
+	device_handler_boot_status(handler, status);
 
 	process_boot_option_queue(handler);
 
@@ -787,12 +867,16 @@ int device_handler_discover(struct device_handler *handler,
 	device_handler_discover_context_commit(handler, ctx);
 
 out:
-	status->message = talloc_asprintf(status,"Processing %s complete\n",
+	/*
+	 * TRANSLATORS: the format specifier in this string is a Linux
+	 * device identifier, like 'sda1'
+	 */
+	status->message = talloc_asprintf(status,_("Processing %s complete"),
 				dev->device->id);
-	boot_status(handler, status);
+	device_handler_boot_status(handler, status);
 
 	talloc_free(status);
-	talloc_free(ctx);
+	talloc_unlink(handler, ctx);
 
 	return 0;
 }
@@ -806,24 +890,33 @@ int device_handler_dhcp(struct device_handler *handler,
 
 	status = talloc_zero(handler, struct boot_status);
 	status->type = BOOT_STATUS_INFO;
-	status->message = talloc_asprintf(status, "Processing dhcp event on %s",
+	/*
+	 * TRANSLATORS: this format specifier will be the name of a network
+	 * device, like 'eth0'.
+	 */
+	status->message = talloc_asprintf(status, _("Processing dhcp event on %s"),
 				dev->device->id);
-	boot_status(handler, status);
+	device_handler_boot_status(handler, status);
 
 	/* create our context */
 	ctx = device_handler_discover_context_create(handler, dev);
+	talloc_steal(ctx, event);
 	ctx->event = event;
 
 	iterate_parsers(ctx);
 
 	device_handler_discover_context_commit(handler, ctx);
 
-	status->message = talloc_asprintf(status,"Processing %s complete\n",
+	/*
+	 * TRANSLATORS: this format specifier will be the name of a network
+	 * device, like 'eth0'.
+	 */
+	status->message = talloc_asprintf(status,_("Processing %s complete"),
 				dev->device->id);
-	boot_status(handler, status);
+	device_handler_boot_status(handler, status);
 
 	talloc_free(status);
-	talloc_free(ctx);
+	talloc_unlink(handler, ctx);
 
 	return 0;
 }
@@ -837,8 +930,8 @@ int device_handler_conf(struct device_handler *handler,
 
 	status = talloc_zero(handler, struct boot_status);
 	status->type = BOOT_STATUS_INFO;
-	status->message = talloc_asprintf(status, "Processing user config");
-	boot_status(handler, status);
+	status->message = talloc_asprintf(status, _("Processing user config"));
+	device_handler_boot_status(handler, status);
 
 	/* create our context */
 	ctx = device_handler_discover_context_create(handler, dev);
@@ -849,11 +942,11 @@ int device_handler_conf(struct device_handler *handler,
 	device_handler_discover_context_commit(handler, ctx);
 
 	status->message = talloc_asprintf(status,
-				"Processing user config complete");
-	boot_status(handler, status);
+				_("Processing user config complete"));
+	device_handler_boot_status(handler, status);
 
 	talloc_free(status);
-	talloc_free(ctx);
+	talloc_unlink(handler, ctx);
 
 	return 0;
 }
@@ -889,7 +982,7 @@ void device_handler_boot(struct device_handler *handler,
 	platform_pre_boot();
 
 	handler->pending_boot = boot(handler, opt, cmd, handler->dry_run,
-			boot_status, handler);
+			device_handler_boot_status, handler);
 	handler->pending_boot_is_default = false;
 }
 
@@ -981,10 +1074,12 @@ static char *device_from_addr(void *ctx, struct pb_url *url)
 
 	rc = process_run_sync(p);
 
-	if (rc) {
+	if (rc || p->exit_status) {
 		/* ip has complained for some reason; most likely
 		 * there is no route to the host - bail out */
-		pb_debug("%s: No route to %s\n",__func__,url->host);
+		pb_debug("%s: `ip` returns non-zero exit status\n", __func__);
+		pb_debug("ip buf: %s\n", p->stdout_buf);
+		process_release(p);
 		return NULL;
 	}
 
@@ -1007,9 +1102,8 @@ static char *device_from_addr(void *ctx, struct pb_url *url)
 	return dev;
 }
 
-
 void device_handler_process_url(struct device_handler *handler,
-		const char *url)
+		const char *url, const char *mac, const char *ip)
 {
 	struct discover_context *ctx;
 	struct discover_device *dev;
@@ -1035,20 +1129,38 @@ void device_handler_process_url(struct device_handler *handler,
 	event->type = EVENT_TYPE_USER;
 	event->action = EVENT_ACTION_CONF;
 
-	event->params = talloc_array(event, struct param, 1);
-	param = &event->params[0];
-	param->name = talloc_strdup(event, "pxeconffile");
-	param->value = talloc_strdup(event, url);
-	event->n_params = 1;
+	if (url[strlen(url) - 1] == '/') {
+		event->params = talloc_array(event, struct param, 3);
+		param = &event->params[0];
+		param->name = talloc_strdup(event, "pxepathprefix");
+		param->value = talloc_strdup(event, url);
+		param = &event->params[1];
+		param->name = talloc_strdup(event, "mac");
+		param->value = talloc_strdup(event, mac);
+		param = &event->params[2];
+		param->name = talloc_strdup(event, "ip");
+		param->value = talloc_strdup(event, ip);
+		event->n_params = 3;
+	} else {
+		event->params = talloc_array(event, struct param, 1);
+		param = &event->params[0];
+		param->name = talloc_strdup(event, "pxeconffile");
+		param->value = talloc_strdup(event, url);
+		event->n_params = 1;
+	}
 
 	pb_url = pb_url_parse(event, event->params->value);
-	if (!pb_url || !pb_url->host) {
+	if (!pb_url || (pb_url->scheme != pb_url_file && !pb_url->host)) {
 		status->message = talloc_asprintf(handler,
 					_("Invalid config URL!"));
 		goto msg;
 	}
 
-	event->device = device_from_addr(event, pb_url);
+	if (pb_url->scheme == pb_url_file)
+		event->device = talloc_asprintf(event, "local");
+	else
+		event->device = device_from_addr(event, pb_url);
+
 	if (!event->device) {
 		status->message = talloc_asprintf(status,
 					_("Unable to route to host %s"),
@@ -1057,25 +1169,80 @@ void device_handler_process_url(struct device_handler *handler,
 	}
 
 	dev = discover_device_create(handler, event->device);
+	if (pb_url->scheme == pb_url_file)
+		dev->device->type = DEVICE_TYPE_ANY;
 	ctx = device_handler_discover_context_create(handler, dev);
+	talloc_steal(ctx, event);
 	ctx->event = event;
 
 	iterate_parsers(ctx);
 
 	device_handler_discover_context_commit(handler, ctx);
 
-	talloc_free(ctx);
+	talloc_unlink(handler, ctx);
 
 	status->type = BOOT_STATUS_INFO;
 	status->message = talloc_asprintf(status, _("Config file %s parsed"),
 					pb_url->file);
 msg:
-	boot_status(handler, status);
+	device_handler_boot_status(handler, status);
 	talloc_free(status);
 }
 
 #ifndef PETITBOOT_TEST
 
+/**
+ * context_commit - Commit a temporary discovery context to the handler,
+ * and notify the clients about any new options / devices
+ */
+void device_handler_discover_context_commit(struct device_handler *handler,
+		struct discover_context *ctx)
+{
+	struct discover_device *dev = ctx->device;
+	struct discover_boot_option *opt, *tmp;
+
+	if (!device_lookup_by_id(handler, dev->device->id))
+		device_handler_add_device(handler, dev);
+
+	/* move boot options from the context to the device */
+	list_for_each_entry_safe(&ctx->boot_options, opt, tmp, list) {
+		list_remove(&opt->list);
+
+		/* All boot options need at least a kernel image */
+		if (!opt->boot_image || !opt->boot_image->url) {
+			pb_log("boot option %s is missing boot image, ignoring\n",
+				opt->option->id);
+			talloc_free(opt);
+			continue;
+		}
+
+		if (boot_option_resolve(opt, handler)) {
+			pb_log("boot option %s is resolved, "
+					"sending to clients\n",
+					opt->option->id);
+			list_add_tail(&dev->boot_options, &opt->list);
+			talloc_steal(dev, opt);
+			boot_option_finalise(handler, opt);
+			notify_boot_option(handler, opt);
+		} else {
+			if (!opt->source->resolve_resource) {
+				pb_log("parser %s gave us an unresolved "
+					"resource (%s), but no way to "
+					"resolve it\n",
+					opt->source->name, opt->option->id);
+				talloc_free(opt);
+			} else {
+				pb_log("boot option %s is unresolved, "
+						"adding to queue\n",
+						opt->option->id);
+				list_add(&handler->unresolved_boot_options,
+						&opt->list);
+				talloc_steal(handler, opt);
+			}
+		}
+	}
+}
+
 static void device_handler_update_lang(const char *lang)
 {
 	const char *cur_lang;
@@ -1125,28 +1292,44 @@ static void device_handler_reinit_sources(struct device_handler *handler)
 			handler->dry_run);
 }
 
-static const char *fs_parameters(unsigned int rw_flags, const char *fstype)
+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)
 {
-	if ((rw_flags | MS_RDONLY) != MS_RDONLY)
-		return "";
+	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;
 
-	/* Avoid writing back to the disk on journaled filesystems */
-	if (!strncmp(fstype, "ext4", strlen("ext4")))
-		return "norecovery";
-	if (!strncmp(fstype, "xfs", strlen("xfs")))
-		return "norecovery";
+	/* 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;
+	}
 
-	return "";
+	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;
 
-	rc = stat(dev->device_path, &devstat);
+	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;
@@ -1177,6 +1360,7 @@ static bool check_existing_mount(struct discover_device *dev)
 
 		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;
@@ -1194,9 +1378,55 @@ static bool check_existing_mount(struct discover_device *dev)
 	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;
+	const char *fstype, *device_path;
 	int rc;
 
 	if (!dev->device_path)
@@ -1212,13 +1442,6 @@ static int mount_device(struct discover_device *dev)
 	if (!fstype)
 		return 0;
 
-	/* ext3 treats the norecovery option as an error, so mount the device
-	 * as an ext4 filesystem instead */
-	if (!strncmp(fstype, "ext3", strlen("ext3"))) {
-		pb_debug("Mounting ext3 filesystem as ext4\n");
-		fstype = talloc_asprintf(dev, "ext4");
-	}
-
 	dev->mount_path = join_paths(dev, mount_base(),
 					dev->device_path);
 
@@ -1228,20 +1451,25 @@ static int mount_device(struct discover_device *dev)
 		goto err_free;
 	}
 
+	device_path = get_device_path(dev);
+
 	pb_log("mounting device %s read-only\n", dev->device_path);
-	errno = 0;
-	rc = mount(dev->device_path, dev->mount_path, fstype,
-			MS_RDONLY | MS_SILENT,
-			fs_parameters(MS_RDONLY, fstype));
+	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",
-			dev->device_path, strerror(errno));
+			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:
@@ -1252,33 +1480,43 @@ err_free:
 
 static int umount_device(struct discover_device *dev)
 {
+	const char *device_path;
 	int rc;
 
 	if (!dev->mounted || !dev->unmount)
 		return 0;
 
-	pb_log("unmounting device %s\n", dev->device_path);
+	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;
+	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;
 
@@ -1287,16 +1525,19 @@ int device_request_write(struct discover_device *dev, bool *release)
 
 	fstype = discover_device_get_param(dev, "ID_FS_TYPE");
 
-	pb_log("remounting device %s read-write\n", dev->device_path);
+	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\n", dev->mount_path);
+		pb_log("Failed to unmount %s: %s\n",
+		       dev->mount_path, strerror(errno));
 		return -1;
 	}
-	rc = mount(dev->device_path, dev->mount_path, fstype,
-			MS_SILENT,
-			fs_parameters(MS_REMOUNT, fstype));
+
+	rc = try_mount(device_path, dev->mount_path, fstype,
+		       MS_SILENT, dev->ramdisk);
 	if (rc)
 		goto mount_ro;
 
@@ -1305,33 +1546,93 @@ int device_request_write(struct discover_device *dev, bool *release)
 	return 0;
 
 mount_ro:
-	pb_log("Unable to remount device %s read-write\n", dev->device_path);
-	rc = mount(dev->device_path, dev->mount_path, fstype,
-			MS_RDONLY | MS_SILENT,
-			fs_parameters(MS_RDONLY, fstype));
+	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\n", dev->device_path);
+		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;
+	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", dev->device_path);
-	mount(dev->device_path, dev->mount_path, "",
-			MS_REMOUNT | MS_RDONLY | MS_SILENT,
-			fs_parameters(MS_RDONLY, fstype));
-	dev->mounted_rw = false;
+	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;
+}
+
+void device_sync_snapshots(struct device_handler *handler, const char *device)
+{
+	struct discover_device *dev = NULL;
+	unsigned int i;
+
+	if (device) {
+		/* Find matching device and sync */
+		dev = device_lookup_by_name(handler, device);
+		if (!dev) {
+			pb_log("%s: device name '%s' unrecognised\n",
+				__func__, device);
+			return;
+		}
+		if (dev->ramdisk)
+			device_release_write(dev, true);
+		else
+			pb_log("%s has no snapshot to merge, skipping\n",
+				dev->device->id);
+		return;
+	}
+
+	/* Otherwise sync all relevant devices */
+	for (i = 0; i < handler->n_devices; i++) {
+		dev = handler->devices[i];
+		if (dev->device->type != DEVICE_TYPE_DISK &&
+			dev->device->type != DEVICE_TYPE_USB)
+			continue;
+		if (dev->ramdisk)
+			device_release_write(dev, true);
+		else
+			pb_log("%s has no snapshot to merge, skipping\n",
+				dev->device->id);
+	}
 }
 
 #else
 
+void device_handler_discover_context_commit(
+		struct device_handler *handler __attribute__((unused)),
+		struct discover_context *ctx __attribute__((unused)))
+{
+	pb_log("%s stubbed out for test cases\n", __func__);
+}
+
 static void device_handler_update_lang(const char *lang __attribute__((unused)))
 {
 }
@@ -1370,5 +1671,10 @@ void device_release_write(struct discover_device *dev __attribute__((unused)),
 {
 }
 
-#endif
+void device_sync_snapshots(
+		struct device_handler *handler __attribute__((unused)),
+		const char *device __attribute__((unused)))
+{
+}
 
+#endif