discover: Keep track of available ramdisk devices

Store information on available ramdisk devices when they are recognised
by udev, and add functions to 'reserve' and 'release' these devices.

This will be used to associate device-mapper snapshots with a backing
ramdisk in a following patch.

Signed-off-by: Samuel Mendoza-Jonas <sam.mj@au1.ibm.com>

2 files changed, 112 insertions, 0 deletions

diff --git a/discover/device-handler.c b/discover/device-handler.c
index d2b50b5..cd16399 100644
--- a/discover/device-handler.c
+++ b/discover/device-handler.c
@@ -56,6 +56,9 @@ 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 +322,7 @@ 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 +337,17 @@ 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);
 }
@@ -750,6 +759,95 @@ void device_handler_add_device(struct device_handler *handler,
 		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
  * array, but has only just been initialised by the hotplug source.
  */
diff --git a/discover/device-handler.h b/discover/device-handler.h
index b592c46..5877733 100644
--- a/discover/device-handler.h
+++ b/discover/device-handler.h
@@ -26,6 +26,7 @@ struct discover_device {
 
 	char			*mount_path;
 	const char		*device_path;
+	struct ramdisk_device	*ramdisk;
 	bool			mounted;
 	bool			mounted_rw;
 	bool			unmount;
@@ -59,6 +60,14 @@ struct discover_context {
 	void			*test_data;
 };
 
+struct ramdisk_device {
+	const char	*path;
+	char		*snapshot;
+	char		*origin;
+	char		*base;
+	unsigned int	sectors;
+};
+
 struct device_handler *device_handler_init(struct discover_server *server,
 		struct waitset *waitset, int dry_run);
 
@@ -72,6 +81,11 @@ struct discover_device *discover_device_create(struct device_handler *handler,
 		const char *id);
 void device_handler_add_device(struct device_handler *handler,
 		struct discover_device *device);
+void device_handler_add_ramdisk(struct device_handler *handler,
+		const char *path);
+struct ramdisk_device *device_handler_get_ramdisk(
+		struct device_handler *handler);
+void device_handler_release_ramdisk(struct discover_device *device);
 int device_handler_discover(struct device_handler *handler,
 		struct discover_device *dev);
 int device_handler_dhcp(struct device_handler *handler,