Merge pull request #403 from Ostrokrzew/zero

Introduce zero-metadata command

casadm/cas_lib.c

@@ -2926,3 +2926,47 @@ int check_cache_device(const char *device_path)
 
 	return SUCCESS;
 }
+
+int zero_md(const char *cache_device){
+	struct kcas_cache_check_device cmd_info;
+	char zero_page[4096] = {0};
+	int fd = 0;
+
+	/* check if given cache device exists */
+	fd = open(cache_device, O_RDONLY);
+	if (fd < 0) {
+		cas_printf(LOG_ERR, "Device '%s' not found.\n", cache_device);
+		return FAILURE;
+	}
+	close(fd);
+
+	/* don't delete metadata if cache is in use */
+	if (check_cache_already_added(cache_device) == FAILURE) {
+		cas_printf(LOG_ERR, "Cache device '%s' is already used as cache. "
+				"Please stop cache to clear metadata.\n", cache_device);
+		return FAILURE;
+	}
+
+	/* don't delete metadata if device hasn't got CAS's metadata */
+	_check_cache_device(cache_device, &cmd_info);
+	if (!cmd_info.is_cache_device) {
+		cas_printf(LOG_ERR, "Device '%s' does not contain OpenCAS's metadata.\n", cache_device);
+		return FAILURE;
+	}
+
+	fd = open(cache_device, O_WRONLY | O_SYNC);
+	if (fd < 0) {
+		cas_printf(LOG_ERR, "Error while opening '%s' to purge metadata.\n", cache_device);
+		return FAILURE;
+	}
+
+	if(write(fd, zero_page, 4096) != 4096) {
+		close(fd);
+		cas_printf(LOG_ERR, "Error while wiping out metadata from device '%s'.\n", cache_device);
+		return FAILURE;
+	}
+
+	close(fd);
+	cas_printf(LOG_INFO, "OpenCAS's metadata wiped succesfully from device '%s'.\n", cache_device);
+	return SUCCESS;
+}

casadm/cas_lib.h

@@ -267,6 +267,14 @@ int validate_str_stats_filters(const char* s);
 int validate_str_output_format(const char* s);
 int validate_str_metadata_mode(const char* s);
 
+/**
+ * @brief clear metadata
+ *
+ * @param[in] cache_device device to which zeroing cache's metadata applies
+ * @return 0 if succeed, 1 if failed
+ */
+int zero_md(const char *cache_device);
+
 /**
  * @brief calculate flush progress
  *

casadm/cas_main.c

@@ -1945,6 +1945,51 @@ void io_class_help(app *app_values, cli_command *cmd)
 
 static int handle_help();
 
+struct {
+	const char *device;
+} static zero_params = {
+	.device = ""
+};
+
+static cli_option zero_options[] = {
+	{'d', "device", "Path to device on which metadata would be cleared", 1, "DEVICE", CLI_OPTION_REQUIRED},
+	{0}
+};
+
+/* Parser of option for zeroing metadata command */
+int zero_handle_option(char *opt, const char **arg)
+{
+	if (!strcmp(opt, "device")) {
+		if(validate_device_name(arg[0]) == FAILURE)
+			return FAILURE;
+		zero_params.device = arg[0];
+
+	} else {
+		return FAILURE;
+	}
+
+	return 0;
+}
+
+int handle_zero()
+{
+	int cache_device = 0;
+
+	cache_device = open(zero_params.device, O_RDONLY);
+
+	if (cache_device < 0) {
+		cas_printf(LOG_ERR, "Couldn't open cache device %s.\n", zero_params.device);
+		return FAILURE;
+	}
+
+	if (close(cache_device) < 0) {
+		cas_printf(LOG_ERR, "Couldn't close the cache device.\n");
+		return FAILURE;
+	}
+
+	return zero_md(zero_params.device);
+}
+
 static cli_command cas_commands[] = {
 		{
 			.name = "start-cache",
@@ -2132,6 +2177,16 @@ static cli_command cas_commands[] = {
 			.handle = handle_help,
 			.help = NULL
 		},
+		{
+			.name = "zero-metadata",
+			.desc = "Clear metadata from caching device",
+			.long_desc = NULL,
+			.options = zero_options,
+			.command_handle_opts = zero_handle_option,
+			.handle = handle_zero,
+			.flags = CLI_SU_REQUIRED,
+			.help = NULL
+		},
 		{
 			.name = "script",
 			.options = script_params_options,