lvm2/lib/metadata/writecache_manip.c

/*
 * Copyright (C) 2014-2015 Red Hat, Inc. All rights reserved.
 *
 * This file is part of LVM2.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU Lesser General Public License v.2.1.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "lib/misc/lib.h"
#include "lib/metadata/metadata.h"
#include "lib/locking/locking.h"
#include "lib/misc/lvm-string.h"
#include "lib/commands/toolcontext.h"
#include "lib/display/display.h"
#include "lib/metadata/segtype.h"
#include "lib/activate/activate.h"
#include "lib/config/defaults.h"

int lv_is_writecache_origin(const struct logical_volume *lv)
{
	struct lv_segment *seg;

	/* Make sure there's exactly one segment in segs_using_this_lv! */
	if (dm_list_empty(&lv->segs_using_this_lv) ||
	    (dm_list_size(&lv->segs_using_this_lv) > 1))
		return 0;

	seg = get_only_segment_using_this_lv(lv);
	return seg && lv_is_writecache(seg->lv) && !lv_is_pending_delete(seg->lv) && (seg_lv(seg, 0) == lv);
}

int lv_is_writecache_cachevol(const struct logical_volume *lv)
{
	struct seg_list *sl;

	dm_list_iterate_items(sl, &lv->segs_using_this_lv) {
		if (!sl->seg || !sl->seg->lv || !sl->seg->writecache)
			continue;
		if (lv_is_writecache(sl->seg->lv) && (sl->seg->writecache == lv))
			return 1;
	}
	return 0;
}

static int _lv_writecache_detach(struct cmd_context *cmd, struct logical_volume *lv,
				 struct logical_volume *lv_fast)
{
	struct lv_segment *seg = first_seg(lv);
	struct logical_volume *origin;

	if (!seg_is_writecache(seg)) {
		log_error("LV %s segment is not writecache.", display_lvname(lv));
		return 0;
	}

	if (!seg->writecache) {
		log_error("LV %s writecache segment has no writecache.", display_lvname(lv));
		return 0;
	}

	if (!(origin = seg_lv(seg, 0))) {
		log_error("LV %s writecache segment has no origin", display_lvname(lv));
		return 0;
	}

	if (!remove_seg_from_segs_using_this_lv(seg->writecache, seg))
		return_0;

	lv_set_visible(seg->writecache);

	lv->status &= ~WRITECACHE;
	seg->writecache = NULL;

	lv_fast->status &= ~LV_CACHE_VOL;

	if (!remove_layer_from_lv(lv, origin))
		return_0;

	if (!lv_remove(origin))
		return_0;

	return 1;
}

static int _get_writecache_kernel_error(struct cmd_context *cmd,
					struct logical_volume *lv,
					uint32_t *kernel_error)
{
	struct lv_with_info_and_seg_status status;

	memset(&status, 0, sizeof(status));
	status.seg_status.type = SEG_STATUS_NONE;

	status.seg_status.seg = first_seg(lv);

	/* FIXME: why reporter_pool? */
	if (!(status.seg_status.mem = dm_pool_create("reporter_pool", 1024))) {
		log_error("Failed to get mem for LV status.");
		return 0;
	}

	if (!lv_info_with_seg_status(cmd, first_seg(lv), &status, 1, 1)) {
		log_error("Failed to get device mapper status for %s", display_lvname(lv));
		goto fail;
	}

	if (!status.info.exists) {
		log_error("No device mapper info exists for %s", display_lvname(lv));
		goto fail;
	}

	if (status.seg_status.type != SEG_STATUS_WRITECACHE) {
		log_error("Invalid device mapper status type (%d) for %s",
			  (uint32_t)status.seg_status.type, display_lvname(lv));
		goto fail;
	}

	*kernel_error = status.seg_status.writecache->error;

	dm_pool_destroy(status.seg_status.mem);
	return 1;

fail:
	dm_pool_destroy(status.seg_status.mem);
	return 0;
}

int lv_detach_writecache_cachevol(struct logical_volume *lv, int noflush)
{
	struct cmd_context *cmd = lv->vg->cmd;
	struct logical_volume *lv_fast;
	uint32_t kernel_error = 0;

	lv_fast = first_seg(lv)->writecache;

	if (noflush)
		goto detach;

	/*
	 * Activate LV internally since the LV needs to be active to flush.
	 * LV_TEMPORARY should keep the LV from being exposed to the user
	 * and being accessed.
	 */

	lv->status |= LV_TEMPORARY;

	if (!activate_lv(cmd, lv)) {
		log_error("Failed to activate LV %s for flushing writecache.", display_lvname(lv));
		return 0;
	}

	if (!sync_local_dev_names(cmd)) {
		log_error("Failed to sync local devices before detaching writecache.");
		return 0;
	}

	if (!lv_writecache_message(lv, "flush")) {
		log_error("Failed to flush writecache for %s.", display_lvname(lv));
		if (!deactivate_lv(cmd, lv))
			log_error("Failed to deactivate %s.", display_lvname(lv));
		return 0;
	}

	if (!_get_writecache_kernel_error(cmd, lv, &kernel_error)) {
		log_error("Failed to get writecache error status for %s.", display_lvname(lv));
		if (!deactivate_lv(cmd, lv))
			log_error("Failed to deactivate %s.", display_lvname(lv));
		return 0;
	}

	if (kernel_error) {
		log_error("Failed to flush writecache (error %u) for %s.", kernel_error, display_lvname(lv));
		deactivate_lv(cmd, lv);
		return 0;
	}

	if (!deactivate_lv(cmd, lv)) {
		log_error("Failed to deactivate LV %s for detaching writecache.", display_lvname(lv));
		return 0;
	}

	lv->status &= ~LV_TEMPORARY;

 detach:
	if (!_lv_writecache_detach(cmd, lv, lv_fast)) {
		log_error("Failed to detach writecache from %s", display_lvname(lv));
		return 0;
	}

	return 1;
}