]> git.ozlabs.org Git - petitboot/blobdiff - discover/device-handler.c
ui/ncurses: Interpret left/right keys as up/down
[petitboot] / discover / device-handler.c
index dd3aee92ca35d0385880b190f60a379494152ad8..43b9541aba9187c2198593f88f85cd5699763b60 100644 (file)
@@ -5,6 +5,7 @@
 #include <string.h>
 #include <errno.h>
 #include <mntent.h>
+#include <locale.h>
 #include <sys/stat.h>
 #include <sys/wait.h>
 #include <sys/mount.h>
 #include <system/system.h>
 #include <process/process.h>
 #include <url/url.h>
+#include <i18n/i18n.h>
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+#include <arpa/inet.h>
 
 #include "device-handler.h"
 #include "discover-server.h"
+#include "devmapper.h"
 #include "user-event.h"
 #include "platform.h"
 #include "event.h"
 #include "boot.h"
 #include "udev.h"
 #include "network.h"
+#include "ipmi.h"
+
+enum default_priority {
+       DEFAULT_PRIORITY_REMOTE         = 1,
+       DEFAULT_PRIORITY_LOCAL_FIRST    = 2,
+       DEFAULT_PRIORITY_LOCAL_LAST     = 0xfe,
+       DEFAULT_PRIORITY_DISABLED       = 0xff,
+};
 
 struct device_handler {
        struct discover_server  *server;
@@ -41,12 +57,17 @@ 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;
        unsigned int            sec_to_boot;
 
        struct discover_boot_option *default_boot_option;
+       int                     default_boot_option_priority;
+
        struct list             unresolved_boot_options;
 
        struct boot_task        *pending_boot;
@@ -59,6 +80,8 @@ static int umount_device(struct discover_device *dev);
 static int device_handler_init_sources(struct device_handler *handler);
 static void device_handler_reinit_sources(struct device_handler *handler);
 
+static void device_handler_update_lang(const char *lang);
+
 void discover_context_add_boot_option(struct discover_context *ctx,
                struct discover_boot_option *boot_option)
 {
@@ -285,6 +308,9 @@ struct device_handler *device_handler_init(struct discover_server *server,
 
        parser_init();
 
+       if (config_get()->safe_mode)
+               return handler;
+
        rc = device_handler_init_sources(handler);
        if (rc) {
                talloc_free(handler);
@@ -297,6 +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);
@@ -308,13 +335,20 @@ void device_handler_reinit(struct device_handler *handler)
        list_init(&handler->unresolved_boot_options);
 
        /* drop all devices */
-       for (i = 0; i < handler->n_devices; i++)
+       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);
 }
@@ -344,6 +378,11 @@ void device_handler_remove(struct device_handler *handler,
                talloc_free(opt);
        }
 
+       /* if this is a network device, we have to unregister it from the
+        * network code */
+       if (device->device->type == DEVICE_TYPE_NETWORK)
+               network_unregister_device(handler->network, device);
+
        handler->n_devices--;
        memmove(&handler->devices[i], &handler->devices[i + 1],
                (handler->n_devices - i) * sizeof(handler->devices[0]));
@@ -373,7 +412,7 @@ static void countdown_status(struct device_handler *handler,
        status.progress = -1;
        status.detail = NULL;
        status.message = talloc_asprintf(handler,
-                       "Booting %s in %u sec", opt->option->name, sec);
+                       _("Booting in %d sec: %s"), sec, opt->option->name);
 
        discover_server_notify_boot_status(handler->server, &status);
 
@@ -406,61 +445,133 @@ 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);
        handler->pending_boot_is_default = true;
        return 0;
 }
 
-static bool priority_match(struct boot_priority *prio,
-               struct discover_boot_option *opt)
+struct {
+       enum ipmi_bootdev       ipmi_type;
+       enum device_type        device_type;
+} 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 },
+};
+
+static bool ipmi_device_type_matches(enum ipmi_bootdev ipmi_type,
+               enum device_type device_type)
 {
-       return prio->type == opt->device->device->type ||
-               prio->type == DEVICE_TYPE_ANY;
+       unsigned int i;
+
+       for (i = 0; i < ARRAY_SIZE(device_type_map); i++) {
+               if (device_type_map[i].device_type == device_type)
+                       return device_type_map[i].ipmi_type == ipmi_type;
+       }
+
+       return false;
 }
 
-static int default_option_priority(struct discover_boot_option *opt)
+static int autoboot_option_priority(const struct config *config,
+                               struct discover_boot_option *opt)
 {
-       const struct config *config;
-       struct boot_priority *prio;
+       enum device_type type = opt->device->device->type;
+       const char *uuid = opt->device->uuid;
+       struct autoboot_option *auto_opt;
        unsigned int i;
 
+       for (i = 0; i < config->n_autoboot_opts; i++) {
+               auto_opt = &config->autoboot_opts[i];
+               if (auto_opt->boot_type == BOOT_DEVICE_UUID)
+                       if (!strcmp(auto_opt->uuid, uuid))
+                               return DEFAULT_PRIORITY_LOCAL_FIRST + i;
+
+               if (auto_opt->boot_type == BOOT_DEVICE_TYPE)
+                       if (auto_opt->type == type ||
+                           auto_opt->type == DEVICE_TYPE_ANY)
+                               return DEFAULT_PRIORITY_LOCAL_FIRST + i;
+       }
+
+       return -1;
+}
+
+/*
+ * We have different priorities to resolve conflicts between boot options that
+ * report to be the default for their device. This function assigns a priority
+ * for these options.
+ */
+static enum default_priority default_option_priority(
+               struct discover_boot_option *opt)
+{
+       const struct config *config;
+
        config = config_get();
 
-       for (i = 0; i < config->n_boot_priorities; i++) {
-               prio = &config->boot_priorities[i];
-               if (priority_match(prio, opt))
-                       return prio->priority;
+       /* We give highest priority to IPMI-configured boot options. If
+        * we have an IPMI bootdev configuration set, then we don't allow
+        * any other defaults */
+       if (config->ipmi_bootdev) {
+               bool ipmi_match = ipmi_device_type_matches(config->ipmi_bootdev,
+                               opt->device->device->type);
+               if (ipmi_match)
+                       return DEFAULT_PRIORITY_REMOTE;
+
+               pb_debug("handler: disabled default priority due to "
+                               "non-matching IPMI type %x\n",
+                               config->ipmi_bootdev);
+               return DEFAULT_PRIORITY_DISABLED;
        }
 
-       return 0;
+       /* Next, try to match the option against the user-defined autoboot
+        * options, either by device UUID or type. */
+       if (config->n_autoboot_opts) {
+               int boot_match = autoboot_option_priority(config, opt);
+               if (boot_match > 0)
+                       return boot_match;
+       }
+
+       /* If the option didn't match any entry in the array, it is disabled */
+       pb_debug("handler: disabled default priority due to "
+                       "non-matching UUID or type\n");
+       return DEFAULT_PRIORITY_DISABLED;
 }
 
 static void set_default(struct device_handler *handler,
                struct discover_boot_option *opt)
 {
-       int new_prio;
+       enum default_priority cur_prio, new_prio;
 
        if (!handler->autoboot_enabled)
                return;
 
+       pb_debug("handler: new default option: %s\n", opt->option->id);
+
        new_prio = default_option_priority(opt);
 
-       /* A negative priority indicates that we don't want to boot this device
-        * by default */
-       if (new_prio < 0)
+       /* Anything outside our range prevents a default boot */
+       if (new_prio >= DEFAULT_PRIORITY_DISABLED)
                return;
 
+       pb_debug("handler: calculated priority %d\n", new_prio);
+
        /* Resolve any conflicts: if we have a new default option, it only
         * replaces the current if it has a higher priority. */
        if (handler->default_boot_option) {
-               int cur_prio;
 
-               cur_prio = default_option_priority(
-                                       handler->default_boot_option);
+               cur_prio = handler->default_boot_option_priority;
 
-               if (new_prio > cur_prio) {
+               if (new_prio < cur_prio) {
+                       pb_log("handler: new prio %d beats "
+                                       "old prio %d for %s\n",
+                                       new_prio, cur_prio,
+                                       handler->default_boot_option
+                                               ->option->id);
                        handler->default_boot_option = opt;
+                       handler->default_boot_option_priority = new_prio;
                        /* extend the timeout a little, so the user sees some
                         * indication of the change */
                        handler->sec_to_boot += 2;
@@ -471,8 +582,9 @@ static void set_default(struct device_handler *handler,
 
        handler->sec_to_boot = config_get()->autoboot_timeout_sec;
        handler->default_boot_option = opt;
+       handler->default_boot_option_priority = new_prio;
 
-       pb_log("Boot option %s set as default, timeout %u sec.\n",
+       pb_log("handler: boot option %s set as default, timeout %u sec.\n",
               opt->option->id, handler->sec_to_boot);
 
        default_timeout(handler);
@@ -589,6 +701,7 @@ struct discover_context *device_handler_discover_context_create(
 
        ctx = talloc_zero(handler, struct discover_context);
        ctx->device = device;
+       ctx->network = handler->network;
        list_init(&ctx->boot_options);
 
        return ctx;
@@ -646,6 +759,97 @@ void device_handler_add_device(struct device_handler *handler,
                                struct discover_device *, handler->n_devices);
        handler->devices[handler->n_devices - 1] = device;
 
+       if (device->device->type == DEVICE_TYPE_NETWORK)
+               network_register_device(handler->network, device);
+}
+
+void device_handler_add_ramdisk(struct device_handler *handler,
+               const char *path)
+{
+       struct ramdisk_device *dev;
+       unsigned int i;
+
+       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 {
+                       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_release_ramdisk(struct discover_device *device)
+{
+       struct ramdisk_device *ramdisk = device->ramdisk;
+
+       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
@@ -655,8 +859,22 @@ int device_handler_discover(struct device_handler *handler,
                struct discover_device *dev)
 {
        struct discover_context *ctx;
+       struct boot_status *status;
        int rc;
 
+       status = talloc_zero(handler, struct boot_status);
+       status->type = BOOT_STATUS_INFO;
+       /*
+        * 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);
+
        process_boot_option_queue(handler);
 
        /* create our context */
@@ -677,6 +895,15 @@ int device_handler_discover(struct device_handler *handler,
        device_handler_discover_context_commit(handler, ctx);
 
 out:
+       /*
+        * 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);
+
+       talloc_free(status);
        talloc_free(ctx);
 
        return 0;
@@ -687,6 +914,17 @@ int device_handler_dhcp(struct device_handler *handler,
                struct discover_device *dev, struct event *event)
 {
        struct discover_context *ctx;
+       struct boot_status *status;
+
+       status = talloc_zero(handler, struct boot_status);
+       status->type = BOOT_STATUS_INFO;
+       /*
+        * 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);
 
        /* create our context */
        ctx = device_handler_discover_context_create(handler, dev);
@@ -696,6 +934,15 @@ int device_handler_dhcp(struct device_handler *handler,
 
        device_handler_discover_context_commit(handler, ctx);
 
+       /*
+        * 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);
+
+       talloc_free(status);
        talloc_free(ctx);
 
        return 0;
@@ -705,19 +952,30 @@ int device_handler_dhcp(struct device_handler *handler,
 int device_handler_conf(struct device_handler *handler,
                struct discover_device *dev, struct pb_url *url)
 {
-        struct discover_context *ctx;
+       struct discover_context *ctx;
+       struct boot_status *status;
+
+       status = talloc_zero(handler, struct boot_status);
+       status->type = BOOT_STATUS_INFO;
+       status->message = talloc_asprintf(status, _("Processing user config"));
+       boot_status(handler, status);
 
-        /* create our context */
-        ctx = device_handler_discover_context_create(handler, dev);
-        ctx->conf_url = url;
+       /* create our context */
+       ctx = device_handler_discover_context_create(handler, dev);
+       ctx->conf_url = url;
 
-        iterate_parsers(ctx);
+       iterate_parsers(ctx);
 
-        device_handler_discover_context_commit(handler, ctx);
+       device_handler_discover_context_commit(handler, ctx);
 
-        talloc_free(ctx);
+       status->message = talloc_asprintf(status,
+                               _("Processing user config complete"));
+       boot_status(handler, status);
 
-        return 0;
+       talloc_free(status);
+       talloc_free(ctx);
+
+       return 0;
 }
 
 static struct discover_boot_option *find_boot_option_by_id(
@@ -747,6 +1005,9 @@ void device_handler_boot(struct device_handler *handler,
 
        if (handler->pending_boot)
                boot_cancel(handler->pending_boot);
+
+       platform_pre_boot();
+
        handler->pending_boot = boot(handler, opt, cmd, handler->dry_run,
                        boot_status, handler);
        handler->pending_boot_is_default = false;
@@ -779,7 +1040,7 @@ void device_handler_cancel_default(struct device_handler *handler)
        status.type = BOOT_STATUS_INFO;
        status.progress = -1;
        status.detail = NULL;
-       status.message = "Default boot cancelled";
+       status.message = _("Default boot cancelled");
 
        discover_server_notify_boot_status(handler->server, &status);
 }
@@ -787,13 +1048,183 @@ void device_handler_cancel_default(struct device_handler *handler)
 void device_handler_update_config(struct device_handler *handler,
                struct config *config)
 {
-       config_set(config);
+       int rc;
+
+       rc = config_set(config);
+       if (rc)
+               return;
+
        discover_server_notify_config(handler->server, config);
+       device_handler_update_lang(config->lang);
        device_handler_reinit(handler);
 }
 
+static char *device_from_addr(void *ctx, struct pb_url *url)
+{
+       char *ipaddr, *buf, *tok, *dev = NULL;
+       const char *delim = " ";
+       struct sockaddr_in *ip;
+       struct sockaddr_in si;
+       struct addrinfo *res;
+       struct process *p;
+       int rc;
+
+       /* Note: IPv4 only */
+       rc = inet_pton(AF_INET, url->host, &(si.sin_addr));
+       if (rc > 0) {
+               ipaddr = url->host;
+       } else {
+               /* need to turn hostname into a valid IP */
+               rc = getaddrinfo(url->host, NULL, NULL, &res);
+               if (rc) {
+                       pb_debug("%s: Invalid URL\n",__func__);
+                       return NULL;
+               }
+               ipaddr = talloc_array(ctx,char,INET_ADDRSTRLEN);
+               ip = (struct sockaddr_in *) res->ai_addr;
+               inet_ntop(AF_INET, &(ip->sin_addr), ipaddr, INET_ADDRSTRLEN);
+               freeaddrinfo(res);
+       }
+
+       const char *argv[] = {
+               pb_system_apps.ip,
+               "route", "show", "to", "match",
+               ipaddr,
+               NULL
+       };
+
+       p = process_create(ctx);
+
+       p->path = pb_system_apps.ip;
+       p->argv = argv;
+       p->keep_stdout = true;
+
+       rc = process_run_sync(p);
+
+       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: `ip` returns non-zero exit status\n", __func__);
+               pb_debug("ip buf: %s\n", p->stdout_buf);
+               process_release(p);
+               return NULL;
+       }
+
+       buf = p->stdout_buf;
+       /* If a route is found, ip-route output will be of the form
+        * "... dev DEVNAME ... " */
+       tok = strtok(buf, delim);
+       while (tok) {
+               if (!strcmp(tok, "dev")) {
+                       tok = strtok(NULL, delim);
+                       dev = talloc_strdup(ctx, tok);
+                       break;
+               }
+               tok = strtok(NULL, delim);
+       }
+
+       process_release(p);
+       if (dev)
+               pb_debug("%s: Found interface '%s'\n", __func__,dev);
+       return dev;
+}
+
+void device_handler_process_url(struct device_handler *handler,
+               const char *url, const char *mac, const char *ip)
+{
+       struct discover_context *ctx;
+       struct discover_device *dev;
+       struct boot_status *status;
+       struct pb_url *pb_url;
+       struct event *event;
+       struct param *param;
+
+       status = talloc(handler, struct boot_status);
+
+       status->type = BOOT_STATUS_ERROR;
+       status->progress = 0;
+       status->detail = talloc_asprintf(status,
+                       _("Received config URL %s"), url);
+
+       if (!handler->network) {
+               status->message = talloc_asprintf(handler,
+                                       _("No network configured"));
+               goto msg;
+       }
+
+       event = talloc(handler, struct event);
+       event->type = EVENT_TYPE_USER;
+       event->action = EVENT_ACTION_CONF;
+
+       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) {
+               status->message = talloc_asprintf(handler,
+                                       _("Invalid config URL!"));
+               goto msg;
+       }
+
+       event->device = device_from_addr(event, pb_url);
+       if (!event->device) {
+               status->message = talloc_asprintf(status,
+                                       _("Unable to route to host %s"),
+                                       pb_url->host);
+               goto msg;
+       }
+
+       dev = discover_device_create(handler, event->device);
+       ctx = device_handler_discover_context_create(handler, dev);
+       ctx->event = event;
+
+       iterate_parsers(ctx);
+
+       device_handler_discover_context_commit(handler, ctx);
+
+       talloc_free(ctx);
+
+       status->type = BOOT_STATUS_INFO;
+       status->message = talloc_asprintf(status, _("Config file %s parsed"),
+                                       pb_url->file);
+msg:
+       boot_status(handler, status);
+       talloc_free(status);
+}
+
 #ifndef PETITBOOT_TEST
 
+static void device_handler_update_lang(const char *lang)
+{
+       const char *cur_lang;
+
+       if (!lang)
+               return;
+
+       cur_lang = setlocale(LC_ALL, NULL);
+       if (cur_lang && !strcmp(cur_lang, lang))
+               return;
+
+       setlocale(LC_ALL, lang);
+}
+
 static int device_handler_init_sources(struct device_handler *handler)
 {
        /* init our device sources: udev, network and user events */
@@ -815,6 +1246,13 @@ static int device_handler_init_sources(struct device_handler *handler)
 
 static void device_handler_reinit_sources(struct device_handler *handler)
 {
+       /* if we haven't initialised sources previously (becuase we started in
+        * safe mode), then init once here. */
+       if (!(handler->udev || handler->network || handler->user_event)) {
+               device_handler_init_sources(handler);
+               return;
+       }
+
        udev_reinit(handler->udev);
 
        network_shutdown(handler->network);
@@ -822,14 +1260,44 @@ static void device_handler_reinit_sources(struct device_handler *handler)
                        handler->dry_run);
 }
 
+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;
 
-       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;
@@ -860,6 +1328,7 @@ 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;
@@ -877,9 +1346,55 @@ 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)
@@ -904,19 +1419,25 @@ 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, "");
+       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:
@@ -927,62 +1448,121 @@ 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, *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;
 
-       pb_log("remounting device %s read-write\n", dev->device_path);
-       rc = mount(dev->device_path, dev->mount_path, "",
-                       MS_REMOUNT | MS_SILENT, "");
-       if (rc)
+       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;
 
-       pb_log("remounting device %s read-only\n", dev->device_path);
-       mount(dev->device_path, dev->mount_path, "",
-                       MS_REMOUNT | MS_RDONLY | MS_SILENT, "");
-       dev->mounted_rw = false;
+       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)))
 {