lib/metadata/snapshot_manip.c - manifest_repos/lvm2 - Git at Google

 /*
  * Copyright (C) 2002-2004 Sistina Software, Inc. All rights reserved.
  * Copyright (C) 2004-2006 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.h"
 #include "metadata.h"
 #include "segtype.h"
 #include "locking.h"
 #include "toolcontext.h"
 #include "lv_alloc.h"
 #include "activate.h"

 #define SNAPSHOT_MIN_CHUNKS	3       /* Minimum number of chunks in snapshot */

 int lv_is_origin(const struct logical_volume *lv)
 {
 	return lv->origin_count ? 1 : 0;
 }

 int lv_is_cow(const struct logical_volume *lv)
 {
 	/* Make sure a merging thin origin isn't confused as a cow LV */
 	return (!lv_is_thin_volume(lv) && !lv_is_origin(lv) && lv->snapshot) ? 1 : 0;
 }

 struct logical_volume *find_cow(const struct logical_volume *snap)
 {
 	return first_seg(snap)->cow;
 }

 /*
  * Some kernels have a bug that they may leak space in the snapshot on crash.
  * If the kernel is buggy, we add some extra space.
  */
 static uint64_t _cow_extra_chunks(struct cmd_context *cmd, uint64_t n_chunks)
 {
 	const struct segment_type *segtype;
 	unsigned attrs = 0;

 	if (activation() &&
 	    (segtype = get_segtype_from_string(cmd, SEG_TYPE_NAME_SNAPSHOT)) &&
 	    segtype->ops->target_present &&
 	    segtype->ops->target_present(cmd, NULL, &attrs) &&
 	    (attrs & SNAPSHOT_FEATURE_FIXED_LEAK))
 		return 0;

 	return (n_chunks + 63) / 64;
 }

 static uint64_t _cow_max_size(struct cmd_context *cmd, uint64_t origin_size, uint32_t chunk_size)
 {
 	/* Snapshot disk layout:
 	 *    COW is divided into chunks
 	 *        1st. chunk is reserved for header
 	 *        2nd. chunk is the 1st. metadata chunk
 	 *        3rd. chunk is the 1st. data chunk
 	 */

 	uint64_t origin_chunks = (origin_size + chunk_size - 1) / chunk_size;
 	uint64_t chunks_per_metadata_area = (uint64_t)chunk_size << (SECTOR_SHIFT - 4);

 	/*
 	 * Note: if origin_chunks is divisible by chunks_per_metadata_area, we
 	 * need one extra metadata chunk as a terminator.
 	 */
 	uint64_t metadata_chunks = (origin_chunks + chunks_per_metadata_area) / chunks_per_metadata_area;
 	uint64_t n_chunks = 1 + origin_chunks + metadata_chunks;

 	return (n_chunks + _cow_extra_chunks(cmd, n_chunks)) * chunk_size;
 }

 uint32_t cow_max_extents(const struct logical_volume *origin, uint32_t chunk_size)
 {
 	uint64_t size = _cow_max_size(origin->vg->cmd, origin->size, chunk_size);
 	uint32_t extent_size = origin->vg->extent_size;
 	uint64_t max_size = (uint64_t) MAX_EXTENT_COUNT * extent_size;

 	if (size % extent_size)
 		size += extent_size - size % extent_size;

 	if (size > max_size)
 		size = max_size; /* Origin is too big for 100% snapshot anyway */

 	return (uint32_t) (size / extent_size);
 }

 int cow_has_min_chunks(const struct volume_group *vg, uint32_t cow_extents, uint32_t chunk_size)
 {
 	if (((uint64_t)vg->extent_size * cow_extents) >= (SNAPSHOT_MIN_CHUNKS * chunk_size))
 		return 1;

 	log_error("Snapshot volume cannot be smaller than " DM_TO_STRING(SNAPSHOT_MIN_CHUNKS)
 		  " chunks (%u extents, %s).", (unsigned)
 		  (((uint64_t) SNAPSHOT_MIN_CHUNKS * chunk_size +
 		    vg->extent_size - 1) / vg->extent_size),
 		  display_size(vg->cmd, (uint64_t) SNAPSHOT_MIN_CHUNKS * chunk_size));

 	return 0;
 }

 int lv_is_cow_covering_origin(const struct logical_volume *lv)
 {
 	return lv_is_cow(lv) &&
 		(lv->size >= _cow_max_size(lv->vg->cmd, origin_from_cow(lv)->size,
 					   find_snapshot(lv)->chunk_size));
 }

 int lv_is_visible(const struct logical_volume *lv)
 {
 	if (lv_is_historical(lv))
 		return 1;

 	if (lv->status & SNAPSHOT)
 		return 0;

 	if (lv_is_cow(lv)) {
 		if (lv_is_virtual_origin(origin_from_cow(lv)))
 			return 1;

 		if (lv_is_merging_cow(lv))
 			return 0;

 		return lv_is_visible(origin_from_cow(lv));
 	}

 	return lv->status & VISIBLE_LV ? 1 : 0;
 }

 int lv_is_merging_cow(const struct logical_volume *cow)
 {
 	struct lv_segment *snap_seg;

 	if (!lv_is_cow(cow))
 		return 0;

 	snap_seg = find_snapshot(cow);

 	/* checks lv_segment's status to see if snapshot is merging */
 	return (snap_seg && (snap_seg->status & MERGING)) ? 1 : 0;
 }

 struct lv_segment *find_snapshot(const struct logical_volume *lv)
 {
 	return lv->snapshot;
 }

 /* Given a cow LV, return its origin */
 struct logical_volume *origin_from_cow(const struct logical_volume *lv)
 {
 	if (lv->snapshot)
 		return lv->snapshot->origin;
 	return NULL;
 }

 void init_snapshot_seg(struct lv_segment *seg, struct logical_volume *origin,
 		       struct logical_volume *cow, uint32_t chunk_size, int merge)
 {
 	seg->chunk_size = chunk_size;
 	seg->origin = origin;
 	seg->cow = cow;

 	lv_set_hidden(cow);

 	cow->snapshot = seg;

 	origin->origin_count++;

 	/* FIXME Assumes an invisible origin belongs to a sparse device */
 	if (!lv_is_visible(origin))
 		origin->status |= VIRTUAL_ORIGIN;

 	seg->lv->status |= (SNAPSHOT | VIRTUAL);
 	if (merge)
 		init_snapshot_merge(seg, origin);

 	dm_list_add(&origin->snapshot_segs, &seg->origin_list);
 }

 void init_snapshot_merge(struct lv_segment *snap_seg,
 			 struct logical_volume *origin)
 {
 	snap_seg->status |= MERGING;
 	origin->snapshot = snap_seg;
 	origin->status |= MERGING;

 	if (seg_is_thin_volume(snap_seg)) {
 		snap_seg->merge_lv = origin;
 		/* Making thin LV invisible with regular log */
 		lv_set_hidden(snap_seg->lv);
 		return;
 	}

 	/*
 	 * Even though lv_is_visible(snap_seg->lv) returns 0,
 	 * the snap_seg->lv (name: snapshotX) is _not_ hidden;
 	 * this is part of the lvm2 snapshot fiction.  Must
 	 * clear VISIBLE_LV directly (lv_set_visible can't)
 	 * - snap_seg->lv->status is used to control whether 'lv'
 	 *   (with user provided snapshot LV name) is visible
 	 * - this also enables vg_validate() to succeed with
 	 *   merge metadata (snap_seg->lv is now "internal")
 	 */
 	snap_seg->lv->status &= ~VISIBLE_LV;
 }

 void clear_snapshot_merge(struct logical_volume *origin)
 {
 	/* clear merge attributes */
 	if (origin->snapshot->merge_lv)
 		/* Removed thin volume has to be visible */
 		lv_set_visible(origin->snapshot->lv);

 	origin->snapshot->merge_lv = NULL;
 	origin->snapshot->status &= ~MERGING;
 	origin->snapshot = NULL;
 	origin->status &= ~MERGING;
 }

 static struct lv_segment *_alloc_snapshot_seg(struct logical_volume *lv)
 {
 	struct lv_segment *seg;
 	const struct segment_type *segtype;

 	segtype = get_segtype_from_string(lv->vg->cmd, SEG_TYPE_NAME_SNAPSHOT);
 	if (!segtype) {
 		log_error("Failed to find snapshot segtype");
 		return NULL;
 	}

 	if (!(seg = alloc_lv_segment(segtype, lv, 0, lv->le_count, 0, 0,
 				     NULL, 0, lv->le_count, 0, 0, 0, NULL))) {
 		log_error("Couldn't allocate new snapshot segment.");
 		return NULL;
 	}

 	dm_list_add(&lv->segments, &seg->list);

 	return seg;
 }

 int vg_add_snapshot(struct logical_volume *origin,
 		    struct logical_volume *cow, union lvid *lvid,
 		    uint32_t extent_count, uint32_t chunk_size)
 {
 	struct logical_volume *snap;
 	struct lv_segment *seg;

 	/*
 	 * Is the cow device already being used ?
 	 */
 	if (lv_is_cow(cow)) {
 		log_error("'%s' is already in use as a snapshot.", cow->name);
 		return 0;
 	}

 	if (cow == origin) {
 		log_error("Snapshot and origin LVs must differ.");
 		return 0;
 	}

 	if (!(snap = lv_create_empty("snapshot%d",
 				     lvid, LVM_READ | LVM_WRITE | VISIBLE_LV,
 				     ALLOC_INHERIT, origin->vg)))
 		return_0;

 	snap->le_count = extent_count;

 	if (!(seg = _alloc_snapshot_seg(snap)))
 		return_0;

 	init_snapshot_seg(seg, origin, cow, chunk_size, 0);

 	return 1;
 }

 int vg_remove_snapshot(struct logical_volume *cow)
 {
 	int merging_snapshot = 0;
 	struct logical_volume *origin = origin_from_cow(cow);
 	int is_origin_active = lv_is_active(origin);

 	if (is_origin_active &&
 	    lv_is_virtual_origin(origin)) {
 		if (!deactivate_lv(origin->vg->cmd, origin)) {
 			log_error("Failed to deactivate logical volume \"%s\"",
 				  origin->name);
 			return 0;
 		}
 		is_origin_active = 0;
 	}

 	dm_list_del(&cow->snapshot->origin_list);
 	origin->origin_count--;

 	if (lv_is_merging_origin(origin) &&
 	    (find_snapshot(origin) == find_snapshot(cow))) {
 		clear_snapshot_merge(origin);
 		/*
 		 * preload origin IFF "snapshot-merge" target is active
 		 * - IMPORTANT: avoids preload if inactivate merge is pending
 		 */
 		if (lv_has_target_type(origin->vg->vgmem, origin, NULL,
 				       TARGET_NAME_SNAPSHOT_MERGE)) {
 			/*
 			 * preload origin to:
 			 * - allow proper release of -cow
 			 * - avoid allocations with other devices suspended
 			 *   when transitioning from "snapshot-merge" to
 			 *   "snapshot-origin after a merge completes.
 			 */
 			merging_snapshot = 1;
 		}
 	}

 	if (!lv_remove(cow->snapshot->lv)) {
 		log_error("Failed to remove internal snapshot LV %s",
 			  cow->snapshot->lv->name);
 		return 0;
 	}

 	cow->snapshot = NULL;
 	lv_set_visible(cow);

 	/* format1 must do the change in one step, with the commit last. */
 	if (!(origin->vg->fid->fmt->features & FMT_MDAS)) {
 		/* Get the lock for COW volume */
 		if (is_origin_active && !activate_lv(cow->vg->cmd, cow)) {
 			log_error("Unable to activate logical volume \"%s\"",
 				  cow->name);
 			return 0;
 		}
 		return 1;
 	}

 	if (!vg_write(origin->vg))
 		return_0;

 	/* Skip call suspend, if device is not active */
 	if (is_origin_active && !suspend_lv(origin->vg->cmd, origin)) {
 		log_error("Failed to refresh %s without snapshot.",
 			  origin->name);
 		vg_revert(origin->vg);
 		return 0;
 	}
 	if (!vg_commit(origin->vg))
 		return_0;

 	if (is_origin_active) {
 		/*
 		 * If the snapshot was active and the COW LV is taken away
 		 * the LV lock on cluster has to be grabbed, so use
 		 * activate_lv() which resumes suspend cow device.
 		 */
 		if (!merging_snapshot && !activate_lv(cow->vg->cmd, cow)) {
 			log_error("Failed to activate %s.", cow->name);
 			return 0;
 		}

 		if (!resume_lv(origin->vg->cmd, origin)) {
 			log_error("Failed to resume %s.", origin->name);
 			return 0;
 		}

 		/*
 		 * For merged snapshot and clustered VG activate cow LV so
 		 * the following call to deactivate_lv() can clean-up table
 		 * entries. For this clustered lock need to be held.
 		 */
 		if (vg_is_clustered(cow->vg) &&
 		    merging_snapshot && !activate_lv(cow->vg->cmd, cow)) {
 			log_error("Failed to activate %s.", cow->name);
 			return 0;
 		}
 	}

 	return 1;
 }
	/*
	* Copyright (C) 2002-2004 Sistina Software, Inc. All rights reserved.
	* Copyright (C) 2004-2006 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.h"
	#include "metadata.h"
	#include "segtype.h"
	#include "locking.h"
	#include "toolcontext.h"
	#include "lv_alloc.h"
	#include "activate.h"

	#define SNAPSHOT_MIN_CHUNKS 3 /* Minimum number of chunks in snapshot */

	int lv_is_origin(const struct logical_volume *lv)
	{
	return lv->origin_count ? 1 : 0;
	}

	int lv_is_cow(const struct logical_volume *lv)
	{
	/* Make sure a merging thin origin isn't confused as a cow LV */
	return (!lv_is_thin_volume(lv) && !lv_is_origin(lv) && lv->snapshot) ? 1 : 0;
	}

	struct logical_volume find_cow(const struct logical_volume snap)
	{
	return first_seg(snap)->cow;
	}

	/*
	* Some kernels have a bug that they may leak space in the snapshot on crash.
	* If the kernel is buggy, we add some extra space.
	*/
	static uint64_t _cow_extra_chunks(struct cmd_context *cmd, uint64_t n_chunks)
	{
	const struct segment_type *segtype;
	unsigned attrs = 0;

	if (activation() &&
	(segtype = get_segtype_from_string(cmd, SEG_TYPE_NAME_SNAPSHOT)) &&
	segtype->ops->target_present &&
	segtype->ops->target_present(cmd, NULL, &attrs) &&
	(attrs & SNAPSHOT_FEATURE_FIXED_LEAK))
	return 0;

	return (n_chunks + 63) / 64;
	}

	static uint64_t _cow_max_size(struct cmd_context *cmd, uint64_t origin_size, uint32_t chunk_size)
	{
	/* Snapshot disk layout:
	* COW is divided into chunks
	* 1st. chunk is reserved for header
	* 2nd. chunk is the 1st. metadata chunk
	* 3rd. chunk is the 1st. data chunk
	*/

	uint64_t origin_chunks = (origin_size + chunk_size - 1) / chunk_size;
	uint64_t chunks_per_metadata_area = (uint64_t)chunk_size << (SECTOR_SHIFT - 4);

	/*
	* Note: if origin_chunks is divisible by chunks_per_metadata_area, we
	* need one extra metadata chunk as a terminator.
	*/
	uint64_t metadata_chunks = (origin_chunks + chunks_per_metadata_area) / chunks_per_metadata_area;
	uint64_t n_chunks = 1 + origin_chunks + metadata_chunks;

	return (n_chunks + _cow_extra_chunks(cmd, n_chunks)) * chunk_size;
	}

	uint32_t cow_max_extents(const struct logical_volume *origin, uint32_t chunk_size)
	{
	uint64_t size = _cow_max_size(origin->vg->cmd, origin->size, chunk_size);
	uint32_t extent_size = origin->vg->extent_size;
	uint64_t max_size = (uint64_t) MAX_EXTENT_COUNT * extent_size;

	if (size % extent_size)
	size += extent_size - size % extent_size;

	if (size > max_size)
	size = max_size; /* Origin is too big for 100% snapshot anyway */

	return (uint32_t) (size / extent_size);
	}

	int cow_has_min_chunks(const struct volume_group *vg, uint32_t cow_extents, uint32_t chunk_size)
	{
	if (((uint64_t)vg->extent_size * cow_extents) >= (SNAPSHOT_MIN_CHUNKS * chunk_size))
	return 1;

	log_error("Snapshot volume cannot be smaller than " DM_TO_STRING(SNAPSHOT_MIN_CHUNKS)
	" chunks (%u extents, %s).", (unsigned)
	(((uint64_t) SNAPSHOT_MIN_CHUNKS * chunk_size +
	vg->extent_size - 1) / vg->extent_size),
	display_size(vg->cmd, (uint64_t) SNAPSHOT_MIN_CHUNKS * chunk_size));

	return 0;
	}

	int lv_is_cow_covering_origin(const struct logical_volume *lv)
	{
	return lv_is_cow(lv) &&
	(lv->size >= _cow_max_size(lv->vg->cmd, origin_from_cow(lv)->size,
	find_snapshot(lv)->chunk_size));
	}

	int lv_is_visible(const struct logical_volume *lv)
	{
	if (lv_is_historical(lv))
	return 1;

	if (lv->status & SNAPSHOT)
	return 0;

	if (lv_is_cow(lv)) {
	if (lv_is_virtual_origin(origin_from_cow(lv)))
	return 1;

	if (lv_is_merging_cow(lv))
	return 0;

	return lv_is_visible(origin_from_cow(lv));
	}

	return lv->status & VISIBLE_LV ? 1 : 0;
	}

	int lv_is_merging_cow(const struct logical_volume *cow)
	{
	struct lv_segment *snap_seg;

	if (!lv_is_cow(cow))
	return 0;

	snap_seg = find_snapshot(cow);

	/* checks lv_segment's status to see if snapshot is merging */
	return (snap_seg && (snap_seg->status & MERGING)) ? 1 : 0;
	}

	struct lv_segment find_snapshot(const struct logical_volume lv)
	{
	return lv->snapshot;
	}

	/* Given a cow LV, return its origin */
	struct logical_volume origin_from_cow(const struct logical_volume lv)
	{
	if (lv->snapshot)
	return lv->snapshot->origin;
	return NULL;
	}

	void init_snapshot_seg(struct lv_segment seg, struct logical_volume origin,
	struct logical_volume *cow, uint32_t chunk_size, int merge)
	{
	seg->chunk_size = chunk_size;
	seg->origin = origin;
	seg->cow = cow;

	lv_set_hidden(cow);

	cow->snapshot = seg;

	origin->origin_count++;

	/* FIXME Assumes an invisible origin belongs to a sparse device */
	if (!lv_is_visible(origin))
	origin->status \|= VIRTUAL_ORIGIN;

	seg->lv->status \|= (SNAPSHOT \| VIRTUAL);
	if (merge)
	init_snapshot_merge(seg, origin);

	dm_list_add(&origin->snapshot_segs, &seg->origin_list);
	}

	void init_snapshot_merge(struct lv_segment *snap_seg,
	struct logical_volume *origin)
	{
	snap_seg->status \|= MERGING;
	origin->snapshot = snap_seg;
	origin->status \|= MERGING;

	if (seg_is_thin_volume(snap_seg)) {
	snap_seg->merge_lv = origin;
	/* Making thin LV invisible with regular log */
	lv_set_hidden(snap_seg->lv);
	return;
	}

	/*
	* Even though lv_is_visible(snap_seg->lv) returns 0,
	* the snap_seg->lv (name: snapshotX) is _not_ hidden;
	* this is part of the lvm2 snapshot fiction. Must
	* clear VISIBLE_LV directly (lv_set_visible can't)
	* - snap_seg->lv->status is used to control whether 'lv'
	* (with user provided snapshot LV name) is visible
	* - this also enables vg_validate() to succeed with
	* merge metadata (snap_seg->lv is now "internal")
	*/
	snap_seg->lv->status &= ~VISIBLE_LV;
	}

	void clear_snapshot_merge(struct logical_volume *origin)
	{
	/* clear merge attributes */
	if (origin->snapshot->merge_lv)
	/* Removed thin volume has to be visible */
	lv_set_visible(origin->snapshot->lv);

	origin->snapshot->merge_lv = NULL;
	origin->snapshot->status &= ~MERGING;
	origin->snapshot = NULL;
	origin->status &= ~MERGING;
	}

	static struct lv_segment _alloc_snapshot_seg(struct logical_volume lv)
	{
	struct lv_segment *seg;
	const struct segment_type *segtype;

	segtype = get_segtype_from_string(lv->vg->cmd, SEG_TYPE_NAME_SNAPSHOT);
	if (!segtype) {
	log_error("Failed to find snapshot segtype");
	return NULL;
	}

	if (!(seg = alloc_lv_segment(segtype, lv, 0, lv->le_count, 0, 0,
	NULL, 0, lv->le_count, 0, 0, 0, NULL))) {
	log_error("Couldn't allocate new snapshot segment.");
	return NULL;
	}

	dm_list_add(&lv->segments, &seg->list);

	return seg;
	}

	int vg_add_snapshot(struct logical_volume *origin,
	struct logical_volume cow, union lvid lvid,
	uint32_t extent_count, uint32_t chunk_size)
	{
	struct logical_volume *snap;
	struct lv_segment *seg;

	/*
	* Is the cow device already being used ?
	*/
	if (lv_is_cow(cow)) {
	log_error("'%s' is already in use as a snapshot.", cow->name);
	return 0;
	}

	if (cow == origin) {
	log_error("Snapshot and origin LVs must differ.");
	return 0;
	}

	if (!(snap = lv_create_empty("snapshot%d",
	lvid, LVM_READ \| LVM_WRITE \| VISIBLE_LV,
	ALLOC_INHERIT, origin->vg)))
	return_0;

	snap->le_count = extent_count;

	if (!(seg = _alloc_snapshot_seg(snap)))
	return_0;

	init_snapshot_seg(seg, origin, cow, chunk_size, 0);

	return 1;
	}

	int vg_remove_snapshot(struct logical_volume *cow)
	{
	int merging_snapshot = 0;
	struct logical_volume *origin = origin_from_cow(cow);
	int is_origin_active = lv_is_active(origin);

	if (is_origin_active &&
	lv_is_virtual_origin(origin)) {
	if (!deactivate_lv(origin->vg->cmd, origin)) {
	log_error("Failed to deactivate logical volume \"%s\"",
	origin->name);
	return 0;
	}
	is_origin_active = 0;
	}

	dm_list_del(&cow->snapshot->origin_list);
	origin->origin_count--;

	if (lv_is_merging_origin(origin) &&
	(find_snapshot(origin) == find_snapshot(cow))) {
	clear_snapshot_merge(origin);
	/*
	* preload origin IFF "snapshot-merge" target is active
	* - IMPORTANT: avoids preload if inactivate merge is pending
	*/
	if (lv_has_target_type(origin->vg->vgmem, origin, NULL,
	TARGET_NAME_SNAPSHOT_MERGE)) {
	/*
	* preload origin to:
	* - allow proper release of -cow
	* - avoid allocations with other devices suspended
	* when transitioning from "snapshot-merge" to
	* "snapshot-origin after a merge completes.
	*/
	merging_snapshot = 1;
	}
	}

	if (!lv_remove(cow->snapshot->lv)) {
	log_error("Failed to remove internal snapshot LV %s",
	cow->snapshot->lv->name);
	return 0;
	}

	cow->snapshot = NULL;
	lv_set_visible(cow);

	/* format1 must do the change in one step, with the commit last. */
	if (!(origin->vg->fid->fmt->features & FMT_MDAS)) {
	/* Get the lock for COW volume */
	if (is_origin_active && !activate_lv(cow->vg->cmd, cow)) {
	log_error("Unable to activate logical volume \"%s\"",
	cow->name);
	return 0;
	}
	return 1;
	}

	if (!vg_write(origin->vg))
	return_0;

	/* Skip call suspend, if device is not active */
	if (is_origin_active && !suspend_lv(origin->vg->cmd, origin)) {
	log_error("Failed to refresh %s without snapshot.",
	origin->name);
	vg_revert(origin->vg);
	return 0;
	}
	if (!vg_commit(origin->vg))
	return_0;

	if (is_origin_active) {
	/*
	* If the snapshot was active and the COW LV is taken away
	* the LV lock on cluster has to be grabbed, so use
	* activate_lv() which resumes suspend cow device.
	*/
	if (!merging_snapshot && !activate_lv(cow->vg->cmd, cow)) {
	log_error("Failed to activate %s.", cow->name);
	return 0;
	}

	if (!resume_lv(origin->vg->cmd, origin)) {
	log_error("Failed to resume %s.", origin->name);
	return 0;
	}

	/*
	* For merged snapshot and clustered VG activate cow LV so
	* the following call to deactivate_lv() can clean-up table
	* entries. For this clustered lock need to be held.
	*/
	if (vg_is_clustered(cow->vg) &&
	merging_snapshot && !activate_lv(cow->vg->cmd, cow)) {
	log_error("Failed to activate %s.", cow->name);
	return 0;
	}
	}

	return 1;
	}