lib/metadata/lv_manip.c

/*
 * Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
 * Copyright (C) 2004-2014 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 "locking.h"
#include "pv_map.h"
#include "lvm-string.h"
#include "toolcontext.h"
#include "lv_alloc.h"
#include "pv_alloc.h"
#include "display.h"
#include "segtype.h"
#include "archiver.h"
#include "activate.h"
#include "str_list.h"
#include "defaults.h"
#include "lvm-exec.h"
#include "memlock.h"
#include "lvmlockd.h"

typedef enum {
	PREFERRED,
	USE_AREA,
	NEXT_PV,
	NEXT_AREA
} area_use_t;

/* FIXME: remove RAID_METADATA_AREA_LEN macro after defining 'raid_log_extents'*/
#define RAID_METADATA_AREA_LEN 1

/* FIXME These ended up getting used differently from first intended.  Refactor. */
/* Only one of A_CONTIGUOUS_TO_LVSEG, A_CLING_TO_LVSEG, A_CLING_TO_ALLOCED may be set */
#define A_CONTIGUOUS_TO_LVSEG	0x01	/* Must be contiguous to an existing segment */
#define A_CLING_TO_LVSEG	0x02	/* Must use same disks as existing LV segment */
#define A_CLING_TO_ALLOCED	0x04	/* Must use same disks as already-allocated segment */

#define A_CLING_BY_TAGS		0x08	/* Must match tags against existing segment */
#define A_CAN_SPLIT		0x10
#define A_AREA_COUNT_MATCHES	0x20	/* Existing lvseg has same number of areas as new segment */

#define A_POSITIONAL_FILL	0x40	/* Slots are positional and filled using PREFERRED */
#define A_PARTITION_BY_TAGS	0x80	/* No allocated area may share any tag with any other */

/*
 * Constant parameters during a single allocation attempt.
 */
struct alloc_parms {
	alloc_policy_t alloc;
	unsigned flags;		/* Holds A_* */
	struct lv_segment *prev_lvseg;
	uint32_t extents_still_needed;
};

/*
 * Holds varying state of each allocation attempt.
 */
struct alloc_state {
	const struct alloc_parms *alloc_parms;
	struct pv_area_used *areas;
	uint32_t areas_size;
	uint32_t log_area_count_still_needed;	/* Number of areas still needing to be allocated for the log */
	uint32_t allocated;	/* Total number of extents allocated so far */
	uint32_t num_positional_areas;	/* Number of parallel allocations that must be contiguous/cling */
};

struct lv_names {
	const char *old;
	const char *new;
};

enum {
	LV_TYPE_UNKNOWN,
	LV_TYPE_NONE,
	LV_TYPE_PUBLIC,
	LV_TYPE_PRIVATE,
	LV_TYPE_HISTORY,
	LV_TYPE_LINEAR,
	LV_TYPE_STRIPED,
	LV_TYPE_MIRROR,
	LV_TYPE_RAID,
	LV_TYPE_THIN,
	LV_TYPE_CACHE,
	LV_TYPE_SPARSE,
	LV_TYPE_ORIGIN,
	LV_TYPE_THINORIGIN,
	LV_TYPE_MULTITHINORIGIN,
	LV_TYPE_THICKORIGIN,
	LV_TYPE_MULTITHICKORIGIN,
	LV_TYPE_CACHEORIGIN,
	LV_TYPE_EXTTHINORIGIN,
	LV_TYPE_MULTIEXTTHINORIGIN,
	LV_TYPE_SNAPSHOT,
	LV_TYPE_THINSNAPSHOT,
	LV_TYPE_THICKSNAPSHOT,
	LV_TYPE_PVMOVE,
	LV_TYPE_IMAGE,
	LV_TYPE_LOG,
	LV_TYPE_METADATA,
	LV_TYPE_POOL,
	LV_TYPE_DATA,
	LV_TYPE_SPARE,
	LV_TYPE_VIRTUAL,
	LV_TYPE_RAID0,
	LV_TYPE_RAID0_META,
	LV_TYPE_RAID1,
	LV_TYPE_RAID10,
	LV_TYPE_RAID4,
	LV_TYPE_RAID5,
	LV_TYPE_RAID5_LA,
	LV_TYPE_RAID5_RA,
	LV_TYPE_RAID5_LS,
	LV_TYPE_RAID5_RS,
	LV_TYPE_RAID6,
	LV_TYPE_RAID6_ZR,
	LV_TYPE_RAID6_NR,
	LV_TYPE_RAID6_NC,
	LV_TYPE_LOCKD,
	LV_TYPE_SANLOCK
};

static const char *_lv_type_names[] = {
	[LV_TYPE_UNKNOWN] =				"unknown",
	[LV_TYPE_NONE] =				"none",
	[LV_TYPE_PUBLIC] =				"public",
	[LV_TYPE_PRIVATE] =				"private",
	[LV_TYPE_HISTORY] =				"history",
	[LV_TYPE_LINEAR] =				"linear",
	[LV_TYPE_STRIPED] =				"striped",
	[LV_TYPE_MIRROR] =				"mirror",
	[LV_TYPE_RAID] =				"raid",
	[LV_TYPE_THIN] =				"thin",
	[LV_TYPE_CACHE] =				"cache",
	[LV_TYPE_SPARSE] =				"sparse",
	[LV_TYPE_ORIGIN] =				"origin",
	[LV_TYPE_THINORIGIN] =				"thinorigin",
	[LV_TYPE_MULTITHINORIGIN] =			"multithinorigin",
	[LV_TYPE_THICKORIGIN] =				"thickorigin",
	[LV_TYPE_MULTITHICKORIGIN] =			"multithickorigin",
	[LV_TYPE_CACHEORIGIN] =				"cacheorigin",
	[LV_TYPE_EXTTHINORIGIN] =			"extthinorigin",
	[LV_TYPE_MULTIEXTTHINORIGIN] =			"multiextthinorigin",
	[LV_TYPE_SNAPSHOT] =				"snapshot",
	[LV_TYPE_THINSNAPSHOT] =			"thinsnapshot",
	[LV_TYPE_THICKSNAPSHOT] =			"thicksnapshot",
	[LV_TYPE_PVMOVE] =				"pvmove",
	[LV_TYPE_IMAGE] =				"image",
	[LV_TYPE_LOG] =					"log",
	[LV_TYPE_METADATA] =				"metadata",
	[LV_TYPE_POOL] =				"pool",
	[LV_TYPE_DATA] =				"data",
	[LV_TYPE_SPARE] =				"spare",
	[LV_TYPE_VIRTUAL] =				"virtual",
	[LV_TYPE_RAID0] =				SEG_TYPE_NAME_RAID0,
	[LV_TYPE_RAID0_META] =				SEG_TYPE_NAME_RAID0_META,
	[LV_TYPE_RAID1] =				SEG_TYPE_NAME_RAID1,
	[LV_TYPE_RAID10] =				SEG_TYPE_NAME_RAID10,
	[LV_TYPE_RAID4] =				SEG_TYPE_NAME_RAID4,
	[LV_TYPE_RAID5] =				SEG_TYPE_NAME_RAID5,
	[LV_TYPE_RAID5_LA] =				SEG_TYPE_NAME_RAID5_LA,
	[LV_TYPE_RAID5_RA] =				SEG_TYPE_NAME_RAID5_RA,
	[LV_TYPE_RAID5_LS] =				SEG_TYPE_NAME_RAID5_LS,
	[LV_TYPE_RAID5_RS] =				SEG_TYPE_NAME_RAID5_RS,
	[LV_TYPE_RAID6] =				SEG_TYPE_NAME_RAID6,
	[LV_TYPE_RAID6_ZR] =				SEG_TYPE_NAME_RAID6_ZR,
	[LV_TYPE_RAID6_NR] =				SEG_TYPE_NAME_RAID6_NR,
	[LV_TYPE_RAID6_NC] =				SEG_TYPE_NAME_RAID6_NC,
	[LV_TYPE_LOCKD] =				"lockd",
	[LV_TYPE_SANLOCK] =				"sanlock",
};

static int _lv_layout_and_role_mirror(struct dm_pool *mem,
				      const struct logical_volume *lv,
				      struct dm_list *layout,
				      struct dm_list *role,
				      int *public_lv)
{
	int top_level = 0;

	/* non-top-level LVs */
	if (lv_is_mirror_image(lv)) {
		if (!str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_MIRROR]) ||
		    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_IMAGE]))
			goto_bad;
	} else if (lv_is_mirror_log(lv)) {
		if (!str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_MIRROR]) ||
		    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_LOG]))
			goto_bad;
		if (lv_is_mirrored(lv) &&
		    !str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_MIRROR]))
			goto_bad;
	} else if (lv_is_pvmove(lv)) {
		if (!str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_PVMOVE]) ||
		    !str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_MIRROR]))
			goto_bad;
	} else
		top_level = 1;


	if (!top_level) {
		*public_lv = 0;
		return 1;
	}

	/* top-level LVs */
	if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_MIRROR]))
		goto_bad;

	return 1;
bad:
	return 0;
}

static int _lv_layout_and_role_raid(struct dm_pool *mem,
				    const struct logical_volume *lv,
				    struct dm_list *layout,
				    struct dm_list *role,
				    int *public_lv)
{
	int top_level = 0;
	const struct segment_type *segtype;

	/* non-top-level LVs */
	if (lv_is_raid_image(lv)) {
		if (!str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_RAID]) ||
		    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_IMAGE]))
			goto_bad;
	} else if (lv_is_raid_metadata(lv)) {
		if (!str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_RAID]) ||
		    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_METADATA]))
			goto_bad;
	} else if (lv_is_pvmove(lv)) {
		if (!str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_PVMOVE]) ||
		    !str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_RAID]))
			goto_bad;
	} else
		top_level = 1;

	if (!top_level) {
		*public_lv = 0;
		return 1;
	}

	/* top-level LVs */
	if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_RAID]))
		goto_bad;

	segtype = first_seg(lv)->segtype;

	if (segtype_is_raid0(segtype)) {
		if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_RAID0]))
			goto_bad;
	} else if (segtype_is_raid1(segtype)) {
		if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_RAID1]))
			goto_bad;
	} else if (segtype_is_raid10(segtype)) {
		if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_RAID10]))
			goto_bad;
	} else if (segtype_is_raid4(segtype)) {
		if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_RAID4]))
			goto_bad;
	} else if (segtype_is_any_raid5(segtype)) {
		if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_RAID5]))
			goto_bad;

		if (segtype_is_raid5_la(segtype)) {
			if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_RAID5_LA]))
				goto_bad;
		} else if (segtype_is_raid5_ra(segtype)) {
			if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_RAID5_RA]))
				goto_bad;
		} else if (segtype_is_raid5_ls(segtype)) {
			if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_RAID5_LS]))
				goto_bad;
		} else if (segtype_is_raid5_rs(segtype)) {
			if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_RAID5_RS]))
				goto_bad;
		}
	} else if (segtype_is_any_raid6(segtype)) {
		if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_RAID6]))
			goto_bad;

		if (segtype_is_raid6_zr(segtype)) {
			if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_RAID6_ZR]))
				goto_bad;
		} else if (segtype_is_raid6_nr(segtype)) {
			if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_RAID6_NR]))
				goto_bad;
		} else if (segtype_is_raid6_nc(segtype)) {
			if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_RAID6_NC]))
				goto_bad;
		}
	}

	return 1;
bad:
	return 0;
}

static int _lv_layout_and_role_thin(struct dm_pool *mem,
				    const struct logical_volume *lv,
				    struct dm_list *layout,
				    struct dm_list *role,
				    int *public_lv)
{
	int top_level = 0;
	unsigned snap_count;
	struct lv_segment *seg;

	/* non-top-level LVs */
	if (lv_is_thin_pool_metadata(lv)) {
		if (!str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_THIN]) ||
		    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_POOL]) ||
		    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_METADATA]))
			goto_bad;
	} else if (lv_is_thin_pool_data(lv)) {
		if (!str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_THIN]) ||
		    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_POOL]) ||
		    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_DATA]))
			goto_bad;
	} else
		top_level = 1;

	if (!top_level) {
		*public_lv = 0;
		return 1;
	}

	/* top-level LVs */
	if (lv_is_thin_volume(lv)) {
		if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_THIN]) ||
		    !str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_SPARSE]))
			goto_bad;
		if (lv_is_thin_origin(lv, &snap_count)) {
			if (!str_list_add(mem, role, _lv_type_names[LV_TYPE_ORIGIN]) ||
			    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_THINORIGIN]))
				goto_bad;
			if (snap_count > 1 &&
			    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_MULTITHINORIGIN]))
				goto_bad;
		}
		if ((seg = first_seg(lv)) && (seg->origin || seg->external_lv))
			if (!str_list_add(mem, role, _lv_type_names[LV_TYPE_SNAPSHOT]) ||
			    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_THINSNAPSHOT]))
				goto_bad;
	} else if (lv_is_thin_pool(lv)) {
		if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_THIN]) ||
		    !str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_POOL]))
			goto_bad;
		*public_lv = 0;
	}

	if (lv_is_external_origin(lv)) {
		if (!str_list_add(mem, role, _lv_type_names[LV_TYPE_ORIGIN]) ||
		    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_EXTTHINORIGIN]))
			goto_bad;
		if (lv->external_count > 1 &&
		    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_MULTIEXTTHINORIGIN]))
			goto_bad;
	}

	return 1;
bad:
	return 0;
}

static int _lv_layout_and_role_cache(struct dm_pool *mem,
				     const struct logical_volume *lv,
				     struct dm_list *layout,
				     struct dm_list *role,
				     int *public_lv)
{
	int top_level = 0;

	/* non-top-level LVs */
	if (lv_is_cache_pool_metadata(lv)) {
		if (!str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_CACHE]) ||
		    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_POOL]) ||
		    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_METADATA]))
			goto_bad;
	} else if (lv_is_cache_pool_data(lv)) {
		if (!str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_CACHE]) ||
		    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_POOL]) ||
		    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_DATA]))
			goto_bad;
		if (lv_is_cache(lv) &&
		    !str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_CACHE]))
			goto_bad;
	} else if (lv_is_cache_origin(lv)) {
		if (!str_list_add(mem, role, _lv_type_names[LV_TYPE_CACHE]) ||
		    !str_list_add(mem, role, _lv_type_names[LV_TYPE_ORIGIN]) ||
		    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_CACHEORIGIN]))
			goto_bad;
		if (lv_is_cache(lv) &&
		    !str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_CACHE]))
			goto_bad;
	} else
		top_level = 1;

	if (!top_level) {
		*public_lv = 0;
		return 1;
	}

	/* top-level LVs */
	if (lv_is_cache(lv) &&
	    !str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_CACHE]))
		goto_bad;
	else if (lv_is_cache_pool(lv)) {
		if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_CACHE]) ||
		    !str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_POOL]))
			goto_bad;
		*public_lv = 0;
	}

	return 1;
bad:
	return 0;
}

static int _lv_layout_and_role_thick_origin_snapshot(struct dm_pool *mem,
						     const struct logical_volume *lv,
						     struct dm_list *layout,
						     struct dm_list *role,
						     int *public_lv)
{
	if (lv_is_origin(lv)) {
		if (!str_list_add(mem, role, _lv_type_names[LV_TYPE_ORIGIN]) ||
		    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_THICKORIGIN]))
			goto_bad;
		/*
		 * Thin volumes are also marked with virtual flag, but we don't show "virtual"
		 * layout for thin LVs as they have their own keyword for layout - "thin"!
		 * So rule thin LVs out here!
		 */
		if (lv_is_virtual(lv) && !lv_is_thin_volume(lv)) {
			if (!str_list_add_no_dup_check(mem, layout, _lv_type_names[LV_TYPE_VIRTUAL]))
				goto_bad;
			*public_lv = 0;
		}
		if (lv->origin_count > 1 &&
		    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_MULTITHICKORIGIN]))
			goto_bad;
	} else if (lv_is_cow(lv)) {
		if (!str_list_add(mem, role, _lv_type_names[LV_TYPE_SNAPSHOT]) ||
		    !str_list_add_no_dup_check(mem, role, _lv_type_names[LV_TYPE_THICKSNAPSHOT]))
			goto_bad;
	}

	return 1;
bad:
	return 0;
}

int lv_layout_and_role(struct dm_pool *mem, const struct logical_volume *lv,
		       struct dm_list **layout, struct dm_list **role) {
	int linear, striped;
	struct lv_segment *seg;
	int public_lv = 1;

	*layout = *role = NULL;

	if (!(*layout = str_list_create(mem))) {
		log_error("LV layout list allocation failed");
		return 0;
	}

	if (!(*role = str_list_create(mem))) {
		log_error("LV role list allocation failed");
		goto bad;
	}

	if (lv_is_historical(lv)) {
		if (!str_list_add_no_dup_check(mem, *layout, _lv_type_names[LV_TYPE_NONE]) ||
		    !str_list_add_no_dup_check(mem, *role, _lv_type_names[LV_TYPE_HISTORY]))
			goto_bad;
	}

	/* Mirrors and related */
	if ((lv_is_mirror_type(lv) || lv_is_pvmove(lv)) &&
	    !_lv_layout_and_role_mirror(mem, lv, *layout, *role, &public_lv))
		goto_bad;

	/* RAIDs and related */
	if (lv_is_raid_type(lv) &&
	    !_lv_layout_and_role_raid(mem, lv, *layout, *role, &public_lv))
		goto_bad;

	/* Thins and related */
	if ((lv_is_thin_type(lv) || lv_is_external_origin(lv)) &&
	    !_lv_layout_and_role_thin(mem, lv, *layout, *role, &public_lv))
		goto_bad;

	/* Caches and related */
	if ((lv_is_cache_type(lv) || lv_is_cache_origin(lv)) &&
	    !_lv_layout_and_role_cache(mem, lv, *layout, *role, &public_lv))
		goto_bad;

	/* Pool-specific */
	if (lv_is_pool_metadata_spare(lv)) {
		if (!str_list_add_no_dup_check(mem, *role, _lv_type_names[LV_TYPE_POOL]) ||
		    !str_list_add_no_dup_check(mem, *role, _lv_type_names[LV_TYPE_SPARE]))
			goto_bad;
		public_lv = 0;
	}

	/* Old-style origins/snapshots, virtual origins */
	if (!_lv_layout_and_role_thick_origin_snapshot(mem, lv, *layout, *role, &public_lv))
		goto_bad;

	if (lv_is_lockd_sanlock_lv(lv)) {
		if (!str_list_add_no_dup_check(mem, *role, _lv_type_names[LV_TYPE_LOCKD]) ||
		    !str_list_add_no_dup_check(mem, *role, _lv_type_names[LV_TYPE_SANLOCK]))
			goto_bad;
		public_lv = 0;
	}

	/*
	 * If layout not yet determined, it must be either
	 * linear or striped or mixture of these two.
	 */
	if (dm_list_empty(*layout)) {
		linear = striped = 0;
		dm_list_iterate_items(seg, &lv->segments) {
			if (seg_is_linear(seg))
				linear = 1;
			else if (seg_is_striped(seg))
				striped = 1;
			else {
				/*
				 * This should not happen but if it does
				 * we'll see that there's "unknown" layout
				 * present. This means we forgot to detect
				 * the role above and we need add proper
				 * detection for such role!
				 */
				log_warn(INTERNAL_ERROR "WARNING: Failed to properly detect "
					 "layout and role for LV %s/%s.",
					 lv->vg->name, lv->name);
			}
		}

		if (linear &&
		    !str_list_add_no_dup_check(mem, *layout, _lv_type_names[LV_TYPE_LINEAR]))
			goto_bad;

		if (striped &&
		    !str_list_add_no_dup_check(mem, *layout, _lv_type_names[LV_TYPE_STRIPED]))
			goto_bad;

		if (!linear && !striped &&
		    !str_list_add_no_dup_check(mem, *layout, _lv_type_names[LV_TYPE_UNKNOWN]))
			goto_bad;
	}

	/* finally, add either 'public' or 'private' role to the LV */
	if (public_lv) {
		if (!str_list_add_h_no_dup_check(mem, *role, _lv_type_names[LV_TYPE_PUBLIC]))
			goto_bad;
	} else {
		if (!str_list_add_h_no_dup_check(mem, *role, _lv_type_names[LV_TYPE_PRIVATE]))
			goto_bad;
	}

	return 1;
bad:
	dm_pool_free(mem, *layout);

	return 0;
}
struct dm_list_and_mempool {
	struct dm_list *list;
	struct dm_pool *mem;
};
static int _get_pv_list_for_lv(struct logical_volume *lv, void *data)
{
	int dup_found;
	uint32_t s;
	struct pv_list *pvl;
	struct lv_segment *seg;
	struct dm_list *pvs = ((struct dm_list_and_mempool *)data)->list;
	struct dm_pool *mem = ((struct dm_list_and_mempool *)data)->mem;

	dm_list_iterate_items(seg, &lv->segments) {
		for (s = 0; s < seg->area_count; s++) {
			dup_found = 0;

			if (seg_type(seg, s) != AREA_PV)
				continue;

			/* do not add duplicates */
			dm_list_iterate_items(pvl, pvs)
				if (pvl->pv == seg_pv(seg, s))
					dup_found = 1;

			if (dup_found)
				continue;

			if (!(pvl = dm_pool_zalloc(mem, sizeof(*pvl)))) {
				log_error("Failed to allocate memory");
				return 0;
			}

			pvl->pv = seg_pv(seg, s);
			log_debug_metadata("  %s/%s uses %s", lv->vg->name,
					   lv->name, pv_dev_name(pvl->pv));

			dm_list_add(pvs, &pvl->list);
		}
	}

	return 1;
}

/*
 * get_pv_list_for_lv
 * @mem - mempool to allocate the list from.
 * @lv
 * @pvs - The list to add pv_list items to.
 *
 * 'pvs' is filled with 'pv_list' items for PVs that compose the LV.
 * If the 'pvs' list already has items in it, duplicates will not be
 * added.  So, it is safe to repeatedly call this function for different
 * LVs and build up a list of PVs for them all.
 *
 * Memory to create the list is obtained from the mempool provided.
 *
 * Returns: 1 on success, 0 on error
 */
int get_pv_list_for_lv(struct dm_pool *mem,
		       struct logical_volume *lv, struct dm_list *pvs)
{
	struct dm_list_and_mempool context = { pvs, mem };

	log_debug_metadata("Generating list of PVs that %s/%s uses:",
			   lv->vg->name, lv->name);

	if (!_get_pv_list_for_lv(lv, &context))
		return_0;

	return for_each_sub_lv(lv, &_get_pv_list_for_lv, &context);
}

/*
 * get_default_region_size
 * @cmd
 *
 * 'mirror_region_size' and 'raid_region_size' are effectively the same thing.
 * However, "raid" is more inclusive than "mirror", so the name has been
 * changed.  This function checks for the old setting and warns the user if
 * it is being overridden by the new setting (i.e. warn if both settings are
 * present).
 *
 * Note that the config files give defaults in kiB terms, but we
 * return the value in terms of sectors.
 *
 * Returns: default region_size in sectors
 */
static int _get_default_region_size(struct cmd_context *cmd)
{
	int mrs, rrs;

	/*
	 * 'mirror_region_size' is the old setting.  It is overridden
	 * by the new setting, 'raid_region_size'.
	 */
	mrs = 2 * find_config_tree_int(cmd, activation_mirror_region_size_CFG, NULL);
	rrs = 2 * find_config_tree_int(cmd, activation_raid_region_size_CFG, NULL);

	if (!mrs && !rrs)
		return DEFAULT_RAID_REGION_SIZE * 2;

	if (!mrs)
		return rrs;

	if (!rrs)
		return mrs;

	if (mrs != rrs)
		log_verbose("Overriding default 'mirror_region_size' setting"
			    " with 'raid_region_size' setting of %u kiB",
			    rrs / 2);

	return rrs;
}

static int _round_down_pow2(int r)
{
	/* Set all bits to the right of the leftmost set bit */
	r |= (r >> 1);
	r |= (r >> 2);
	r |= (r >> 4);
	r |= (r >> 8);
	r |= (r >> 16);

	/* Pull out the leftmost set bit */
	return r & ~(r >> 1);
}

int get_default_region_size(struct cmd_context *cmd)
{
	int region_size = _get_default_region_size(cmd);

	if (!is_power_of_2(region_size)) {
		region_size = _round_down_pow2(region_size);
		log_verbose("Reducing region size to %u kiB (power of 2).",
			    region_size / 2);
	}

	return region_size;
}

int add_seg_to_segs_using_this_lv(struct logical_volume *lv,
				  struct lv_segment *seg)
{
	struct seg_list *sl;

	dm_list_iterate_items(sl, &lv->segs_using_this_lv) {
		if (sl->seg == seg) {
			sl->count++;
			return 1;
		}
	}

	log_very_verbose("Adding %s:%" PRIu32 " as an user of %s",
			 seg->lv->name, seg->le, lv->name);

	if (!(sl = dm_pool_zalloc(lv->vg->vgmem, sizeof(*sl)))) {
		log_error("Failed to allocate segment list");
		return 0;
	}

	sl->count = 1;
	sl->seg = seg;
	dm_list_add(&lv->segs_using_this_lv, &sl->list);

	return 1;
}

int remove_seg_from_segs_using_this_lv(struct logical_volume *lv,
				       struct lv_segment *seg)
{
	struct seg_list *sl;

	dm_list_iterate_items(sl, &lv->segs_using_this_lv) {
		if (sl->seg != seg)
			continue;
		if (sl->count > 1)
			sl->count--;
		else {
			log_very_verbose("%s:%" PRIu32 " is no longer a user "
					 "of %s", seg->lv->name, seg->le,
					 lv->name);
			dm_list_del(&sl->list);
		}
		return 1;
	}

	log_error(INTERNAL_ERROR "Segment %s:%u is not a user of %s.",
                  seg->lv->name, seg->le, lv->name);
	return 0;
}

/*
 * This is a function specialized for the common case where there is
 * only one segment which uses the LV.
 * e.g. the LV is a layer inserted by insert_layer_for_lv().
 *
 * In general, walk through lv->segs_using_this_lv.
 */
struct lv_segment *get_only_segment_using_this_lv(const struct logical_volume *lv)
{
	struct seg_list *sl;

	if (!lv) {
		log_error(INTERNAL_ERROR "get_only_segment_using_this_lv() called with NULL LV.");
		return NULL;
	}

	dm_list_iterate_items(sl, &lv->segs_using_this_lv) {
		/* Needs to be he only item in list */
		if (!dm_list_end(&lv->segs_using_this_lv, &sl->list))
			break;

		if (sl->count != 1) {
			log_error("%s is expected to have only one segment using it, "
				  "while %s:%" PRIu32 " uses it %d times.",
				  display_lvname(lv), sl->seg->lv->name, sl->seg->le, sl->count);
			return NULL;
		}

		return sl->seg;
	}

	log_error("%s is expected to have only one segment using it, while it has %d.",
		  display_lvname(lv), dm_list_size(&lv->segs_using_this_lv));

	return NULL;
}

/*
 * PVs used by a segment of an LV
 */
struct seg_pvs {
	struct dm_list list;

	struct dm_list pvs;	/* struct pv_list */

	uint32_t le;
	uint32_t len;
};

static struct seg_pvs *_find_seg_pvs_by_le(struct dm_list *list, uint32_t le)
{
	struct seg_pvs *spvs;

	dm_list_iterate_items(spvs, list)
		if (le >= spvs->le && le < spvs->le + spvs->len)
			return spvs;

	return NULL;
}

/*
 * Find first unused LV number.
 */
uint32_t find_free_lvnum(struct logical_volume *lv)
{
	int lvnum_used[MAX_RESTRICTED_LVS + 1] = { 0 };
	uint32_t i = 0;
	struct lv_list *lvl;
	int lvnum;

	dm_list_iterate_items(lvl, &lv->vg->lvs) {
		lvnum = lvnum_from_lvid(&lvl->lv->lvid);
		if (lvnum <= MAX_RESTRICTED_LVS)
			lvnum_used[lvnum] = 1;
	}

	while (lvnum_used[i])
		i++;

	/* FIXME What if none are free? */

	return i;
}

dm_percent_t copy_percent(const struct logical_volume *lv)
{
	uint32_t numerator = 0u, denominator = 0u;
	struct lv_segment *seg;

	dm_list_iterate_items(seg, &lv->segments) {
		denominator += seg->area_len;

		/* FIXME Generalise name of 'extents_copied' field */
		if (((seg_is_raid(seg) && !seg_is_any_raid0(seg)) || seg_is_mirrored(seg)) &&
		    (seg->area_count > 1))
			numerator += seg->extents_copied;
		else
			numerator += seg->area_len;
	}

	return denominator ? dm_make_percent(numerator, denominator) : DM_PERCENT_100;
}

/* Round up extents to next stripe boundary for number of stripes */
static uint32_t _round_to_stripe_boundary(struct volume_group *vg, uint32_t extents,
					  uint32_t stripes, int extend)
{
	uint32_t size_rest, new_extents = extents;

	if (!stripes)
		return extents;

	/* Round up extents to stripe divisible amount */
	if ((size_rest = extents % stripes)) {
		new_extents += extend ? stripes - size_rest : -size_rest;
		log_print_unless_silent("Rounding size %s (%d extents) up to stripe boundary size %s (%d extents).",
					display_size(vg->cmd, (uint64_t) extents * vg->extent_size), extents,
					display_size(vg->cmd, (uint64_t) new_extents * vg->extent_size), new_extents);
	}

	return new_extents;
}

/*
 * All lv_segments get created here.
 */
struct lv_segment *alloc_lv_segment(const struct segment_type *segtype,
				    struct logical_volume *lv,
				    uint32_t le, uint32_t len,
				    uint64_t status,
				    uint32_t stripe_size,
				    struct logical_volume *log_lv,
				    uint32_t area_count,
				    uint32_t area_len,
				    uint32_t chunk_size,
				    uint32_t region_size,
				    uint32_t extents_copied,
				    struct lv_segment *pvmove_source_seg)
{
	struct lv_segment *seg;
	struct dm_pool *mem = lv->vg->vgmem;
	uint32_t areas_sz = area_count * sizeof(*seg->areas);

	if (!segtype) {
		log_error(INTERNAL_ERROR "alloc_lv_segment: Missing segtype.");
		return NULL;
	}

	if (!(seg = dm_pool_zalloc(mem, sizeof(*seg))))
		return_NULL;

	if (!(seg->areas = dm_pool_zalloc(mem, areas_sz))) {
		dm_pool_free(mem, seg);
		return_NULL;
	}

	if (segtype_is_raid(segtype) &&
	    !segtype_is_raid0(segtype) &&
	    !(seg->meta_areas = dm_pool_zalloc(mem, areas_sz))) {
		dm_pool_free(mem, seg); /* frees everything alloced since seg */
		return_NULL;
	}

	seg->segtype = segtype;
	seg->lv = lv;
	seg->le = le;
	seg->len = len;
	seg->status = status;
	seg->stripe_size = stripe_size;
	seg->area_count = area_count;
	seg->area_len = area_len;
	seg->chunk_size = chunk_size;
	seg->region_size = region_size;
	seg->extents_copied = extents_copied;
	seg->pvmove_source_seg = pvmove_source_seg;
	dm_list_init(&seg->tags);
	dm_list_init(&seg->origin_list);
	dm_list_init(&seg->thin_messages);

	if (log_lv && !attach_mirror_log(seg, log_lv))
		return_NULL;

	if (segtype_is_mirror(segtype))
		lv->status |= MIRROR;

	if (segtype_is_mirrored(segtype))
		lv->status |= MIRRORED;

	return seg;
}

static int _release_and_discard_lv_segment_area(struct lv_segment *seg, uint32_t s,
						uint32_t area_reduction, int with_discard)
{
	struct lv_segment *cache_seg;
	struct logical_volume *lv = seg_lv(seg, s);

	if (seg_type(seg, s) == AREA_UNASSIGNED)
		return 1;

	if (seg_type(seg, s) == AREA_PV) {
		if (with_discard && !discard_pv_segment(seg_pvseg(seg, s), area_reduction))
			return_0;

		if (!release_pv_segment(seg_pvseg(seg, s), area_reduction))
			return_0;

		if (seg->area_len == area_reduction)
			seg_type(seg, s) = AREA_UNASSIGNED;

		return 1;
	}

	if (lv_is_mirror_image(lv) ||
	    lv_is_thin_pool_data(lv) ||
	    lv_is_cache_pool_data(lv)) {
		if (!lv_reduce(lv, area_reduction))
			return_0; /* FIXME: any upper level reporting */
		return 1;
	}

	if (seg_is_cache_pool(seg) &&
	    !dm_list_empty(&seg->lv->segs_using_this_lv)) {
		if (!(cache_seg = get_only_segment_using_this_lv(seg->lv)))
			return_0;

		if (!lv_cache_remove(cache_seg->lv))
			return_0;
	}

	if (lv_is_raid_image(lv)) {
		/*
		 * FIXME: Use lv_reduce not lv_remove
		 *  We use lv_remove for now, because I haven't figured out
		 *  why lv_reduce won't remove the LV.
		lv_reduce(lv, area_reduction);
		*/
		if (area_reduction != seg->area_len) {
			log_error("Unable to reduce RAID LV - operation not implemented.");
			return_0;
		} else {
			if (!lv_remove(lv)) {
				log_error("Failed to remove RAID image %s",
					  lv->name);
				return 0;
			}
		}

		/* Remove metadata area if image has been removed */
		if (seg->meta_areas && seg_metalv(seg, s) && (area_reduction == seg->area_len)) {
			if (!lv_reduce(seg_metalv(seg, s),
				       seg_metalv(seg, s)->le_count)) {
				log_error("Failed to remove RAID meta-device %s",
					  seg_metalv(seg, s)->name);
				return 0;
			}
		}
		return 1;
	}

	if (area_reduction == seg->area_len) {
		log_very_verbose("Remove %s:%" PRIu32 "[%" PRIu32 "] from "
				 "the top of LV %s:%" PRIu32,
				 seg->lv->name, seg->le, s,
				 lv->name, seg_le(seg, s));

		if (!remove_seg_from_segs_using_this_lv(lv, seg))
			return_0;
		seg_lv(seg, s) = NULL;
		seg_le(seg, s) = 0;
		seg_type(seg, s) = AREA_UNASSIGNED;
	}

	return 1;
}

int release_and_discard_lv_segment_area(struct lv_segment *seg, uint32_t s, uint32_t area_reduction)
{
	return _release_and_discard_lv_segment_area(seg, s, area_reduction, 1);
}

int release_lv_segment_area(struct lv_segment *seg, uint32_t s, uint32_t area_reduction)
{
	return _release_and_discard_lv_segment_area(seg, s, area_reduction, 0);
}

/*
 * Move a segment area from one segment to another
 */
int move_lv_segment_area(struct lv_segment *seg_to, uint32_t area_to,
			 struct lv_segment *seg_from, uint32_t area_from)
{
	struct physical_volume *pv;
	struct logical_volume *lv;
	uint32_t pe, le;

	switch (seg_type(seg_from, area_from)) {
	case AREA_PV:
		pv = seg_pv(seg_from, area_from);
		pe = seg_pe(seg_from, area_from);

		if (!release_lv_segment_area(seg_from, area_from, seg_from->area_len))
			return_0;

		if (!release_lv_segment_area(seg_to, area_to, seg_to->area_len))
			return_0;

		if (!set_lv_segment_area_pv(seg_to, area_to, pv, pe))
			return_0;

		break;

	case AREA_LV:
		lv = seg_lv(seg_from, area_from);
		le = seg_le(seg_from, area_from);

		if (!release_lv_segment_area(seg_from, area_from, seg_from->area_len))
			return_0;

		if (!release_lv_segment_area(seg_to, area_to, seg_to->area_len))
			return_0;

		if (!set_lv_segment_area_lv(seg_to, area_to, lv, le, 0))
			return_0;

		break;

	case AREA_UNASSIGNED:
		if (!release_lv_segment_area(seg_to, area_to, seg_to->area_len))
			return_0;
	}

	return 1;
}

/*
 * Link part of a PV to an LV segment.
 */
int set_lv_segment_area_pv(struct lv_segment *seg, uint32_t area_num,
			   struct physical_volume *pv, uint32_t pe)
{
	seg->areas[area_num].type = AREA_PV;

	if (!(seg_pvseg(seg, area_num) =
	      assign_peg_to_lvseg(pv, pe, seg->area_len, seg, area_num)))
		return_0;

	return 1;
}

/*
 * Link one LV segment to another.  Assumes sizes already match.
 */
int set_lv_segment_area_lv(struct lv_segment *seg, uint32_t area_num,
			   struct logical_volume *lv, uint32_t le,
			   uint64_t status)
{
	log_very_verbose("Stack %s:%" PRIu32 "[%" PRIu32 "] on LV %s:%" PRIu32,
			 seg->lv->name, seg->le, area_num, lv->name, le);

	if (status & RAID_META) {
		seg->meta_areas[area_num].type = AREA_LV;
		seg_metalv(seg, area_num) = lv;
		if (le) {
			log_error(INTERNAL_ERROR "Meta le != 0");
			return 0;
		}
		seg_metale(seg, area_num) = 0;
	} else {
		seg->areas[area_num].type = AREA_LV;
		seg_lv(seg, area_num) = lv;
		seg_le(seg, area_num) = le;
	}
	lv->status |= status;

	if (!add_seg_to_segs_using_this_lv(lv, seg))
		return_0;

	return 1;
}

/*
 * Prepare for adding parallel areas to an existing segment.
 */
static int _lv_segment_add_areas(struct logical_volume *lv,
				 struct lv_segment *seg,
				 uint32_t new_area_count)
{
	struct lv_segment_area *newareas;
	uint32_t areas_sz = new_area_count * sizeof(*newareas);

	if (!(newareas = dm_pool_zalloc(lv->vg->cmd->mem, areas_sz)))
		return_0;

	memcpy(newareas, seg->areas, seg->area_count * sizeof(*seg->areas));

	seg->areas = newareas;
	seg->area_count = new_area_count;

	return 1;
}

static uint32_t _calc_area_multiple(const struct segment_type *segtype,
				    const uint32_t area_count,
				    const uint32_t stripes)
{
	if (!area_count)
		return 1;

	/* Striped */
	if (segtype_is_striped(segtype))
		return area_count;

	/* Parity RAID (e.g. RAID 4/5/6) */
	if (segtype_is_raid(segtype) && segtype->parity_devs) {
		/*
		 * As articulated in _alloc_init, we can tell by
		 * the area_count whether a replacement drive is
		 * being allocated; and if this is the case, then
		 * there is no area_multiple that should be used.
		 */
		if (area_count <= segtype->parity_devs)
			return 1;

		return area_count - segtype->parity_devs;
	}

	/*
	 * RAID10 - only has 2-way mirror right now.
	 *          If we are to move beyond 2-way RAID10, then
	 *          the 'stripes' argument will always need to
	 *          be given.
	 */
	if (!strcmp(segtype->name, _lv_type_names[LV_TYPE_RAID10])) {
		if (!stripes)
			return area_count / 2;
		return stripes;
	}

	/* Mirrored stripes */
	if (stripes)
		return stripes;

	/* Mirrored */
	return 1;
}

/*
 * Reduce the size of an lv_segment.  New size can be zero.
 */
static int _lv_segment_reduce(struct lv_segment *seg, uint32_t reduction)
{
	uint32_t area_reduction, s;

	/* Caller must ensure exact divisibility */
	if (seg_is_striped(seg)) {
		if (reduction % seg->area_count) {
			log_error("Segment extent reduction %" PRIu32
				  " not divisible by #stripes %" PRIu32,
				  reduction, seg->area_count);
			return 0;
		}
		area_reduction = (reduction / seg->area_count);
	} else
		area_reduction = reduction;

	for (s = 0; s < seg->area_count; s++)
		if (!release_and_discard_lv_segment_area(seg, s, area_reduction))
			return_0;

	seg->len -= reduction;
	seg->area_len -= area_reduction;

	return 1;
}

/*
 * Entry point for all LV reductions in size.
 */
static int _lv_reduce(struct logical_volume *lv, uint32_t extents, int delete)
{
	struct lv_segment *seg;
	uint32_t count = extents;
	uint32_t reduction;
	struct logical_volume *pool_lv;

	if (lv_is_merging_origin(lv)) {
		log_debug_metadata("Dropping snapshot merge of %s to removed origin %s.",
				   find_snapshot(lv)->lv->name, lv->name);
		clear_snapshot_merge(lv);
	}

	dm_list_iterate_back_items(seg, &lv->segments) {
		if (!count)
			break;

		if (seg->len <= count) {
			if (seg->merge_lv) {
				log_debug_metadata("Dropping snapshot merge of removed %s to origin %s.",
						   seg->lv->name, seg->merge_lv->name);
				clear_snapshot_merge(seg->merge_lv);
			}

			/* remove this segment completely */
			/* FIXME Check this is safe */
			if (seg->log_lv && !lv_remove(seg->log_lv))
				return_0;

			if (seg->metadata_lv && !lv_remove(seg->metadata_lv))
				return_0;

			/* Remove cache origin only when removing (not on lv_empty()) */
			if (delete && seg_is_cache(seg)) {
				if (lv_is_pending_delete(seg->lv)) {
					/* Just dropping reference on origin when pending delete */
					if (!remove_seg_from_segs_using_this_lv(seg_lv(seg, 0), seg))
						return_0;
					seg_lv(seg, 0) = NULL;
					seg_le(seg, 0) = 0;
					seg_type(seg, 0) = AREA_UNASSIGNED;
					if (seg->pool_lv && !detach_pool_lv(seg))
						return_0;
				} else if (!lv_remove(seg_lv(seg, 0)))
					return_0;
			}

			if ((pool_lv = seg->pool_lv)) {
				if (!detach_pool_lv(seg))
					return_0;
				/* When removing cached LV, remove pool as well */
				if (seg_is_cache(seg) && !lv_remove(pool_lv))
					return_0;
			}

			dm_list_del(&seg->list);
			reduction = seg->len;
		} else
			reduction = count;

		if (!_lv_segment_reduce(seg, reduction))
			return_0;
		count -= reduction;
	}

	lv->le_count -= extents;
	lv->size = (uint64_t) lv->le_count * lv->vg->extent_size;

	if (!delete)
		return 1;

	if (lv == lv->vg->pool_metadata_spare_lv) {
		lv->status &= ~POOL_METADATA_SPARE;
		lv->vg->pool_metadata_spare_lv = NULL;
	}

	/* Remove the LV if it is now empty */
	if (!lv->le_count && !unlink_lv_from_vg(lv))
		return_0;
	else if (lv->vg->fid->fmt->ops->lv_setup &&
		   !lv->vg->fid->fmt->ops->lv_setup(lv->vg->fid, lv))
		return_0;

	return 1;
}

/*
 * Empty an LV.
 */
int lv_empty(struct logical_volume *lv)
{
	return _lv_reduce(lv, lv->le_count, 0);
}

/*
 * Empty an LV and add error segment.
 */
int replace_lv_with_error_segment(struct logical_volume *lv)
{
	uint32_t len = lv->le_count;

	if (len && !lv_empty(lv))
		return_0;

	/* Minimum size required for a table. */
	if (!len)
		len = 1;

	/*
	 * Since we are replacing the whatever-was-there with
	 * an error segment, we should also clear any flags
	 * that suggest it is anything other than "error".
	 */
	/* FIXME Check for other flags that need removing */
	lv->status &= ~(MIRROR|MIRRORED|PVMOVE|LOCKED);

	/* FIXME Check for any attached LVs that will become orphans e.g. mirror logs */

	if (!lv_add_virtual_segment(lv, 0, len, get_segtype_from_string(lv->vg->cmd, SEG_TYPE_NAME_ERROR)))
		return_0;

	return 1;
}

int lv_refresh_suspend_resume(const struct logical_volume *lv)
{
	struct cmd_context *cmd = lv->vg->cmd;
	int r = 1;

	if (!cmd->partial_activation && lv_is_partial(lv)) {
		log_error("Refusing refresh of partial LV %s."
			  " Use '--activationmode partial' to override.",
			  display_lvname(lv));
		return 0;
	}

	if (!suspend_lv(cmd, lv)) {
		log_error("Failed to suspend %s.", display_lvname(lv));
		r = 0;
	}

	if (!resume_lv(cmd, lv)) {
		log_error("Failed to reactivate %s.", display_lvname(lv));
		r = 0;
	}

	return r;
}

/*
 * Remove given number of extents from LV.
 */
int lv_reduce(struct logical_volume *lv, uint32_t extents)
{
	return _lv_reduce(lv, extents, 1);
}

int historical_glv_remove(struct generic_logical_volume *glv)
{
	struct generic_logical_volume *origin_glv;
	struct glv_list *glvl, *user_glvl;
	struct historical_logical_volume *hlv;
	int reconnected;

	if (!glv || !glv->is_historical)
		return_0;

	hlv = glv->historical;

	if (!(glv = find_historical_glv(hlv->vg, hlv->name, 0, &glvl))) {
		if (!(find_historical_glv(hlv->vg, hlv->name, 1, NULL))) {
			log_error(INTERNAL_ERROR "historical_glv_remove: historical LV %s/-%s not found ",
				  hlv->vg->name, hlv->name);
			return 0;
		} else {
			log_verbose("Historical LV %s/-%s already on removed list ",
				    hlv->vg->name, hlv->name);
			return 1;
		}
	}

	if ((origin_glv = hlv->indirect_origin) &&
	    !remove_glv_from_indirect_glvs(origin_glv, glv))
		return_0;

	dm_list_iterate_items(user_glvl, &hlv->indirect_glvs) {
		reconnected = 0;
		if ((origin_glv && !origin_glv->is_historical) && !user_glvl->glv->is_historical)
			log_verbose("Removing historical connection between %s and %s.",
				     origin_glv->live->name, user_glvl->glv->live->name);
		else if (hlv->vg->cmd->record_historical_lvs) {
			if (!add_glv_to_indirect_glvs(hlv->vg->vgmem, origin_glv, user_glvl->glv))
				return_0;
			reconnected = 1;
		}

		if (!reconnected) {
			/*
			 * Break ancestry chain if we're removing historical LV and tracking
			 * historical LVs is switched off either via:
			 *   - "metadata/record_lvs_history=0" config
			 *   - "--nohistory" cmd line option
			 *
			 * Also, break the chain if we're unable to store such connection at all
			 * because we're removing the very last historical LV that was in between
			 * live LVs - pure live LVs can't store any indirect origin relation in
			 * metadata - we need at least one historical LV to do that!
			 */
			if (user_glvl->glv->is_historical)
				user_glvl->glv->historical->indirect_origin = NULL;
			else
				first_seg(user_glvl->glv->live)->indirect_origin = NULL;
		}
	}

	dm_list_move(&hlv->vg->removed_historical_lvs, &glvl->list);
	return 1;
}

/*
 * Completely remove an LV.
 */
int lv_remove(struct logical_volume *lv)
{
	if (lv_is_historical(lv))
		return historical_glv_remove(lv->this_glv);

	if (!lv_reduce(lv, lv->le_count))
		return_0;

	return 1;
}

/*
 * A set of contiguous physical extents allocated
 */
struct alloced_area {
	struct dm_list list;

	struct physical_volume *pv;
	uint32_t pe;
	uint32_t len;
};

/*
 * Details of an allocation attempt
 */
struct alloc_handle {
	struct cmd_context *cmd;
	struct dm_pool *mem;

	alloc_policy_t alloc;		/* Overall policy */
	int approx_alloc;		/* get as much as possible up to new_extents */
	uint32_t new_extents;		/* Number of new extents required */
	uint32_t area_count;		/* Number of parallel areas */
	uint32_t parity_count;		/* Adds to area_count, but not area_multiple */
	uint32_t area_multiple;		/* seg->len = area_len * area_multiple */
	uint32_t log_area_count;	/* Number of parallel logs */
	uint32_t metadata_area_count;   /* Number of parallel metadata areas */
	uint32_t log_len;		/* Length of log/metadata_area */
	uint32_t region_size;		/* Mirror region size */
	uint32_t total_area_len;	/* Total number of parallel extents */

	unsigned maximise_cling;
	unsigned mirror_logs_separate;	/* Force mirror logs on separate PVs? */

	/*
	 * RAID devices require a metadata area that accompanies each
	 * device.  During initial creation, it is best to look for space
	 * that is new_extents + log_len and then split that between two
	 * allocated areas when found.  'alloc_and_split_meta' indicates
	 * that this is the desired dynamic.
	 *
	 * This same idea is used by cache LVs to get the metadata device
	 * and data device allocated together.
	 */
	unsigned alloc_and_split_meta;
	unsigned split_metadata_is_allocated;	/* Metadata has been allocated */

	const struct dm_config_node *cling_tag_list_cn;

	struct dm_list *parallel_areas;	/* PVs to avoid */

	/*
	 * Contains area_count lists of areas allocated to data stripes
	 * followed by log_area_count lists of areas allocated to log stripes.
	 */
	struct dm_list alloced_areas[0];
};

/*
 * Returns log device size in extents, algorithm from kernel code
 */
#define BYTE_SHIFT 3
static uint32_t _mirror_log_extents(uint32_t region_size, uint32_t pe_size, uint32_t area_len)
{
	size_t area_size, bitset_size, log_size, region_count;

	area_size = (size_t)area_len * pe_size;
	region_count = dm_div_up(area_size, region_size);

	/* Work out how many "unsigned long"s we need to hold the bitset. */
	bitset_size = dm_round_up(region_count, sizeof(uint32_t) << BYTE_SHIFT);
	bitset_size >>= BYTE_SHIFT;

	/* Log device holds both header and bitset. */
	log_size = dm_round_up((MIRROR_LOG_OFFSET << SECTOR_SHIFT) + bitset_size, 1 << SECTOR_SHIFT);
	log_size >>= SECTOR_SHIFT;
	log_size = dm_div_up(log_size, pe_size);

	/*
	 * Kernel requires a mirror to be at least 1 region large.  So,
	 * if our mirror log is itself a mirror, it must be at least
	 * 1 region large.  This restriction may not be necessary for
	 * non-mirrored logs, but we apply the rule anyway.
	 *
	 * (The other option is to make the region size of the log
	 * mirror smaller than the mirror it is acting as a log for,
	 * but that really complicates things.  It's much easier to
	 * keep the region_size the same for both.)
	 */
	return (log_size > (region_size / pe_size)) ? log_size :
		(region_size / pe_size);
}

/* Is there enough total space or should we give up immediately? */
static int _sufficient_pes_free(struct alloc_handle *ah, struct dm_list *pvms,
				uint32_t allocated, uint32_t extents_still_needed)
{
	uint32_t area_extents_needed = (extents_still_needed - allocated) * ah->area_count / ah->area_multiple;
	uint32_t parity_extents_needed = (extents_still_needed - allocated) * ah->parity_count / ah->area_multiple;
	uint32_t metadata_extents_needed = ah->alloc_and_split_meta ? 0 : ah->metadata_area_count * RAID_METADATA_AREA_LEN; /* One each */
	uint32_t total_extents_needed = area_extents_needed + parity_extents_needed + metadata_extents_needed;
	uint32_t free_pes = pv_maps_size(pvms);

	if (total_extents_needed > free_pes) {
		log_error("Insufficient free space: %" PRIu32 " extents needed,"
			  " but only %" PRIu32 " available",
			  total_extents_needed, free_pes);
		return 0;
	}

	return 1;
}

/* For striped mirrors, all the areas are counted, through the mirror layer */
static uint32_t _stripes_per_mimage(struct lv_segment *seg)
{
	struct lv_segment *last_lvseg;

	if (seg_is_mirrored(seg) && seg->area_count && seg_type(seg, 0) == AREA_LV) {
		last_lvseg = dm_list_item(dm_list_last(&seg_lv(seg, 0)->segments), struct lv_segment);
		if (seg_is_striped(last_lvseg))
			return last_lvseg->area_count;
	}

	return 1;
}

static void _init_alloc_parms(struct alloc_handle *ah,
			      struct alloc_parms *alloc_parms,
			      alloc_policy_t alloc,
			      struct lv_segment *prev_lvseg, unsigned can_split,
			      uint32_t allocated, uint32_t extents_still_needed)
{
	alloc_parms->alloc = alloc;
	alloc_parms->prev_lvseg = prev_lvseg;
	alloc_parms->flags = 0;
	alloc_parms->extents_still_needed = extents_still_needed;

	/*
	 * Only attempt contiguous/cling allocation to previous segment
	 * areas if the number of areas matches.
	 */
	if (alloc_parms->prev_lvseg &&
	    ((ah->area_count + ah->parity_count) == prev_lvseg->area_count)) {
		alloc_parms->flags |= A_AREA_COUNT_MATCHES;

		/* Are there any preceding segments we must follow on from? */
		if (alloc_parms->alloc == ALLOC_CONTIGUOUS) {
			alloc_parms->flags |= A_CONTIGUOUS_TO_LVSEG;
			alloc_parms->flags |= A_POSITIONAL_FILL;
		} else if ((alloc_parms->alloc == ALLOC_CLING) ||
			   (alloc_parms->alloc == ALLOC_CLING_BY_TAGS)) {
			alloc_parms->flags |= A_CLING_TO_LVSEG;
			alloc_parms->flags |= A_POSITIONAL_FILL;
		}
	} else
		/*
		 * A cling allocation that follows a successful contiguous
		 * allocation must use the same PVs (or else fail).
		 */
		if ((alloc_parms->alloc == ALLOC_CLING) ||
		    (alloc_parms->alloc == ALLOC_CLING_BY_TAGS)) {
			alloc_parms->flags |= A_CLING_TO_ALLOCED;
			alloc_parms->flags |= A_POSITIONAL_FILL;
		}

	if (alloc_parms->alloc == ALLOC_CLING_BY_TAGS)
		alloc_parms->flags |= A_CLING_BY_TAGS;

	if (!(alloc_parms->alloc & A_POSITIONAL_FILL) &&
	    (alloc_parms->alloc == ALLOC_CONTIGUOUS) &&
	    ah->cling_tag_list_cn)
		alloc_parms->flags |= A_PARTITION_BY_TAGS;

	/*
	 * For normal allocations, if any extents have already been found
	 * for allocation, prefer to place further extents on the same disks as
	 * have already been used.
	 */
	if (ah->maximise_cling &&
	    (alloc_parms->alloc == ALLOC_NORMAL) &&
	    (allocated != alloc_parms->extents_still_needed))
		alloc_parms->flags |= A_CLING_TO_ALLOCED;

	if (can_split)
		alloc_parms->flags |= A_CAN_SPLIT;
}

static int _log_parallel_areas(struct dm_pool *mem, struct dm_list *parallel_areas)
{
	struct seg_pvs *spvs;
	struct pv_list *pvl;
	char *pvnames;

	if (!parallel_areas)
		return 1;

	dm_list_iterate_items(spvs, parallel_areas) {
		if (!dm_pool_begin_object(mem, 256)) {
			log_error("dm_pool_begin_object failed");
			return 0;
		}

		dm_list_iterate_items(pvl, &spvs->pvs) {
			if (!dm_pool_grow_object(mem, pv_dev_name(pvl->pv), strlen(pv_dev_name(pvl->pv)))) {
				log_error("dm_pool_grow_object failed");
				dm_pool_abandon_object(mem);
				return 0;
			}
			if (!dm_pool_grow_object(mem, " ", 1)) {
				log_error("dm_pool_grow_object failed");
				dm_pool_abandon_object(mem);
				return 0;
			}
		}

		if (!dm_pool_grow_object(mem, "\0", 1)) {
			log_error("dm_pool_grow_object failed");
			dm_pool_abandon_object(mem);
			return 0;
		}

		pvnames = dm_pool_end_object(mem);
		log_debug_alloc("Parallel PVs at LE %" PRIu32 " length %" PRIu32 ": %s",
				spvs->le, spvs->len, pvnames);
		dm_pool_free(mem, pvnames);
	}

	return 1;
}

/* Handles also stacking */
static int _setup_lv_size(struct logical_volume *lv, uint32_t extents)
{
	struct lv_segment *thin_pool_seg;

	lv->le_count = extents;
	lv->size = (uint64_t) extents * lv->vg->extent_size;

	if (lv_is_thin_pool_data(lv)) {
		if (!(thin_pool_seg = get_only_segment_using_this_lv(lv)))
			return_0;

		/* Update thin pool segment from the layered LV */
		thin_pool_seg->lv->le_count =
			thin_pool_seg->len =
			thin_pool_seg->area_len = lv->le_count;
		thin_pool_seg->lv->size = lv->size;
	}

	return 1;
}

static int _setup_alloced_segment(struct logical_volume *lv, uint64_t status,
				  uint32_t area_count,
				  uint32_t stripe_size,
				  const struct segment_type *segtype,
				  struct alloced_area *aa,
				  uint32_t region_size)
{
	uint32_t s, extents, area_multiple;
	struct lv_segment *seg;

	area_multiple = _calc_area_multiple(segtype, area_count, 0);
	extents = aa[0].len * area_multiple;

	if (!(seg = alloc_lv_segment(segtype, lv, lv->le_count, extents,
				     status, stripe_size, NULL,
				     area_count,
				     aa[0].len, 0u, region_size, 0u, NULL))) {
		log_error("Couldn't allocate new LV segment.");
		return 0;
	}

	for (s = 0; s < area_count; s++)
		if (!set_lv_segment_area_pv(seg, s, aa[s].pv, aa[s].pe))
			return_0;

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

	extents = aa[0].len * area_multiple;

	if (!_setup_lv_size(lv, lv->le_count + extents))
		return_0;

	return 1;
}

static int _setup_alloced_segments(struct logical_volume *lv,
				   struct dm_list *alloced_areas,
				   uint32_t area_count,
				   uint64_t status,
				   uint32_t stripe_size,
				   const struct segment_type *segtype,
				   uint32_t region_size)
{
	struct alloced_area *aa;

	dm_list_iterate_items(aa, &alloced_areas[0]) {
		if (!_setup_alloced_segment(lv, status, area_count,
					    stripe_size, segtype, aa,
					    region_size))
			return_0;
	}

	return 1;
}

/*
 * This function takes a list of pv_areas and adds them to allocated_areas.
 * If the complete area is not needed then it gets split.
 * The part used is removed from the pv_map so it can't be allocated twice.
 */
static int _alloc_parallel_area(struct alloc_handle *ah, uint32_t max_to_allocate,
				struct alloc_state *alloc_state, uint32_t ix_log_offset)
{
	uint32_t area_len, len;
	uint32_t s, smeta;
	uint32_t ix_log_skip = 0; /* How many areas to skip in middle of array to reach log areas */
	uint32_t total_area_count;
	struct alloced_area *aa;
	struct pv_area *pva;

	total_area_count = ah->area_count + ah->parity_count + alloc_state->log_area_count_still_needed;
	if (!total_area_count) {
		log_warn(INTERNAL_ERROR "_alloc_parallel_area called without any allocation to do.");
		return 1;
	}

	area_len = max_to_allocate / ah->area_multiple;

	/* Reduce area_len to the smallest of the areas */
	for (s = 0; s < ah->area_count + ah->parity_count; s++)
		if (area_len > alloc_state->areas[s].used)
			area_len = alloc_state->areas[s].used;

	len = (ah->alloc_and_split_meta && !ah->split_metadata_is_allocated) ? total_area_count * 2 : total_area_count;
	len *= sizeof(*aa);
	if (!(aa = dm_pool_alloc(ah->mem, len))) {
		log_error("alloced_area allocation failed");
		return 0;
	}

	/*
	 * Areas consists of area_count areas for data stripes, then
	 * ix_log_skip areas to skip, then log_area_count areas to use for the
	 * log, then some areas too small for the log.
	 */
	len = area_len;
	for (s = 0; s < total_area_count; s++) {
		if (s == (ah->area_count + ah->parity_count)) {
			ix_log_skip = ix_log_offset - ah->area_count;
			len = ah->log_len;
		}

		pva = alloc_state->areas[s + ix_log_skip].pva;
		if (ah->alloc_and_split_meta && !ah->split_metadata_is_allocated) {
			/*
			 * The metadata area goes at the front of the allocated
			 * space for now, but could easily go at the end (or
			 * middle!).
			 *
			 * Even though we split these two from the same
			 * allocation, we store the images at the beginning
			 * of the areas array and the metadata at the end.
			 */
			smeta = s + ah->area_count + ah->parity_count;
			aa[smeta].pv = pva->map->pv;
			aa[smeta].pe = pva->start;
			aa[smeta].len = ah->log_len;

			log_debug_alloc("Allocating parallel metadata area %" PRIu32
					" on %s start PE %" PRIu32
					" length %" PRIu32 ".",
					(smeta - (ah->area_count + ah->parity_count)),
					pv_dev_name(aa[smeta].pv), aa[smeta].pe,
					ah->log_len);

			consume_pv_area(pva, ah->log_len);
			dm_list_add(&ah->alloced_areas[smeta], &aa[smeta].list);
		}
		aa[s].len = (ah->alloc_and_split_meta && !ah->split_metadata_is_allocated) ? len - ah->log_len : len;
		/* Skip empty allocations */
		if (!aa[s].len)
			continue;

		aa[s].pv = pva->map->pv;
		aa[s].pe = pva->start;

		log_debug_alloc("Allocating parallel area %" PRIu32
				" on %s start PE %" PRIu32 " length %" PRIu32 ".",
				s, pv_dev_name(aa[s].pv), aa[s].pe, aa[s].len);

		consume_pv_area(pva, aa[s].len);

		dm_list_add(&ah->alloced_areas[s], &aa[s].list);
	}

	/* Only need to alloc metadata from the first batch */
	if (ah->alloc_and_split_meta)
		ah->split_metadata_is_allocated = 1;

	ah->total_area_len += area_len;

	alloc_state->allocated += area_len * ah->area_multiple;

	return 1;
}

/*
 * Call fn for each AREA_PV used by the LV segment at lv:le of length *max_seg_len.
 * If any constituent area contains more than one segment, max_seg_len is
 * reduced to cover only the first.
 * fn should return 0 on error, 1 to continue scanning or >1 to terminate without error.
 * In the last case, this function passes on the return code.
 * FIXME I think some callers are expecting this to check all PV segments used by an LV.
 */
static int _for_each_pv(struct cmd_context *cmd, struct logical_volume *lv,
			uint32_t le, uint32_t len, struct lv_segment *seg,
			uint32_t *max_seg_len,
			uint32_t first_area, uint32_t max_areas,
			int top_level_area_index,
			int only_single_area_segments,
			int (*fn)(struct cmd_context *cmd,
				  struct pv_segment *peg, uint32_t s,
				  void *data),
			void *data)
{
	uint32_t s;
	uint32_t remaining_seg_len, area_len, area_multiple;
	uint32_t stripes_per_mimage = 1;
	int r = 1;

	if (!seg && !(seg = find_seg_by_le(lv, le))) {
		log_error("Failed to find segment for %s extent %" PRIu32,
			  lv->name, le);
		return 0;
	}

	/* Remaining logical length of segment */
	remaining_seg_len = seg->len - (le - seg->le);

	if (remaining_seg_len > len)
		remaining_seg_len = len;

	if (max_seg_len && *max_seg_len > remaining_seg_len)
		*max_seg_len = remaining_seg_len;

	area_multiple = _calc_area_multiple(seg->segtype, seg->area_count, 0);
	area_len = (remaining_seg_len / area_multiple) ? : 1;

	/* For striped mirrors, all the areas are counted, through the mirror layer */
	if (top_level_area_index == -1)
		stripes_per_mimage = _stripes_per_mimage(seg);

	for (s = first_area;
	     s < seg->area_count && (!max_areas || s <= max_areas);
	     s++) {
		if (seg_type(seg, s) == AREA_LV) {
			if (!(r = _for_each_pv(cmd, seg_lv(seg, s),
					       seg_le(seg, s) +
					       (le - seg->le) / area_multiple,
					       area_len, NULL, max_seg_len, 0,
					       (stripes_per_mimage == 1) && only_single_area_segments ? 1U : 0U,
					       (top_level_area_index != -1) ? top_level_area_index : (int) (s * stripes_per_mimage),
					       only_single_area_segments, fn,
					       data)))
				stack;
		} else if (seg_type(seg, s) == AREA_PV)
			if (!(r = fn(cmd, seg_pvseg(seg, s), top_level_area_index != -1 ? (uint32_t) top_level_area_index + s : s, data)))
				stack;
		if (r != 1)
			return r;
	}

	/* FIXME only_single_area_segments used as workaround to skip log LV - needs new param? */
	if (!only_single_area_segments && seg_is_mirrored(seg) && seg->log_lv) {
		if (!(r = _for_each_pv(cmd, seg->log_lv, 0, seg->log_lv->le_count, NULL,
				       NULL, 0, 0, 0, only_single_area_segments,
				       fn, data)))
			stack;
		if (r != 1)
			return r;
	}

	/* FIXME Add snapshot cow, thin meta etc. */

/*
	if (!only_single_area_segments && !max_areas && seg_is_raid(seg)) {
		for (s = first_area; s < seg->area_count; s++) {
			if (seg_metalv(seg, s))
				if (!(r = _for_each_pv(cmd, seg_metalv(seg, s), 0, seg_metalv(seg, s)->le_count, NULL,
						       NULL, 0, 0, 0, 0, fn, data)))
					stack;
			if (r != 1)
				return r;
		}
	}
*/

	return 1;
}

static int _comp_area(const void *l, const void *r)
{
	const struct pv_area_used *lhs = (const struct pv_area_used *) l;
	const struct pv_area_used *rhs = (const struct pv_area_used *) r;

	if (lhs->used < rhs->used)
		return 1;

	else if (lhs->used > rhs->used)
		return -1;

	return 0;
}

/*
 * Search for pvseg that matches condition
 */
struct pv_match {
	int (*condition)(struct pv_match *pvmatch, struct pv_segment *pvseg, struct pv_area *pva);

	struct alloc_handle *ah;
	struct alloc_state *alloc_state;
	struct pv_area *pva;
	const struct dm_config_node *cling_tag_list_cn;
	int s;	/* Area index of match */
};

/*
 * Is PV area on the same PV?
 */
static int _is_same_pv(struct pv_match *pvmatch __attribute((unused)), struct pv_segment *pvseg, struct pv_area *pva)
{
	if (pvseg->pv != pva->map->pv)
		return 0;

	return 1;
}

/*
 * Does PV area have a tag listed in allocation/cling_tag_list that
 * matches EITHER a tag of the PV of the existing segment OR a tag in pv_tags?
 * If tags_list_str is set, then instead we generate a list of matching tags for printing.
 */
static int _match_pv_tags(const struct dm_config_node *cling_tag_list_cn,
			  struct physical_volume *pv1, uint32_t pv1_start_pe, uint32_t area_num,
			  struct physical_volume *pv2, struct dm_list *pv_tags, unsigned validate_only,
			  struct dm_pool *mem, const char **tags_list_str)
{
	const struct dm_config_value *cv;
	const char *str;
	const char *tag_matched;
	struct dm_list *tags_to_match = tags_list_str ? NULL : pv_tags ? : &pv2->tags;
	struct dm_str_list *sl;
	unsigned first_tag = 1;

	if (tags_list_str && !dm_pool_begin_object(mem, 256)) {
		log_error("PV tags string allocation failed");
		return 0;
	}

	for (cv = cling_tag_list_cn->v; cv; cv = cv->next) {
		if (cv->type != DM_CFG_STRING) {
			if (validate_only)
				log_warn("WARNING: Ignoring invalid string in config file entry "
					 "allocation/cling_tag_list");
			continue;
		}
		str = cv->v.str;
		if (!*str) {
			if (validate_only)
				log_warn("WARNING: Ignoring empty string in config file entry "
					 "allocation/cling_tag_list");
			continue;
		}

		if (*str != '@') {
			if (validate_only)
				log_warn("WARNING: Ignoring string not starting with @ in config file entry "
					 "allocation/cling_tag_list: %s", str);
			continue;
		}

		str++;

		if (!*str) {
			if (validate_only)
				log_warn("WARNING: Ignoring empty tag in config file entry "
					 "allocation/cling_tag_list");
			continue;
		}

		if (validate_only)
			continue;

		/* Wildcard matches any tag against any tag. */
		if (!strcmp(str, "*")) {
			if (tags_list_str) {
				dm_list_iterate_items(sl, &pv1->tags) {
					if (!first_tag && !dm_pool_grow_object(mem, ",", 0)) {
						dm_pool_abandon_object(mem);
						log_error("PV tags string extension failed.");
						return 0;
					}
					first_tag = 0;
					if (!dm_pool_grow_object(mem, sl->str, 0)) {
						dm_pool_abandon_object(mem);
						log_error("PV tags string extension failed.");
						return 0;
					}
				}
				continue;
			}
			if (!str_list_match_list(&pv1->tags, tags_to_match, &tag_matched))
				continue;
			else {
				if (!pv_tags)
					log_debug_alloc("Matched allocation PV tag %s on existing %s with free space on %s.",
							tag_matched, pv_dev_name(pv1), pv2 ? pv_dev_name(pv2) : "-");
				else
					log_debug_alloc("Eliminating allocation area %" PRIu32 " at PV %s start PE %" PRIu32
							" from consideration: PV tag %s already used.",
							area_num, pv_dev_name(pv1), pv1_start_pe, tag_matched);
				return 1;
			}
		}

		if (!str_list_match_item(&pv1->tags, str) ||
		    (tags_to_match && !str_list_match_item(tags_to_match, str)))
			continue;
		else {
			if (tags_list_str) {
				if (!first_tag && !dm_pool_grow_object(mem, ",", 0)) {
					dm_pool_abandon_object(mem);
					log_error("PV tags string extension failed.");
					return 0;
				}
				first_tag = 0;
				if (!dm_pool_grow_object(mem, str, 0)) {
					dm_pool_abandon_object(mem);
					log_error("PV tags string extension failed.");
					return 0;
				}
				continue;
			}
			if (!pv_tags)
				log_debug_alloc("Matched allocation PV tag %s on existing %s with free space on %s.",
						str, pv_dev_name(pv1), pv2 ? pv_dev_name(pv2) : "-");
			else
				log_debug_alloc("Eliminating allocation area %" PRIu32 " at PV %s start PE %" PRIu32
						" from consideration: PV tag %s already used.",
						area_num, pv_dev_name(pv1), pv1_start_pe, str);
			return 1;
		}
	}

	if (tags_list_str) {
		if (!dm_pool_grow_object(mem, "\0", 1)) {
			dm_pool_abandon_object(mem);
			log_error("PV tags string extension failed.");
			return 0;
		}
		*tags_list_str = dm_pool_end_object(mem);
		return 1;
	}

	return 0;
}

static int _validate_tag_list(const struct dm_config_node *cling_tag_list_cn)
{
	return _match_pv_tags(cling_tag_list_cn, NULL, 0, 0, NULL, NULL, 1, NULL, NULL);
}

static const char *_tags_list_str(struct alloc_handle *ah, struct physical_volume *pv1)
{
	const char *tags_list_str;

	if (!_match_pv_tags(ah->cling_tag_list_cn, pv1, 0, 0, NULL, NULL, 0, ah->mem, &tags_list_str))
		return_NULL;

	return tags_list_str;
}

/*
 * Does PV area have a tag listed in allocation/cling_tag_list that
 * matches a tag in the pv_tags list?
 */
static int _pv_has_matching_tag(const struct dm_config_node *cling_tag_list_cn,
				struct physical_volume *pv1, uint32_t pv1_start_pe, uint32_t area_num,
				struct dm_list *pv_tags)
{
	return _match_pv_tags(cling_tag_list_cn, pv1, pv1_start_pe, area_num, NULL, pv_tags, 0, NULL, NULL);
}

/*
 * Does PV area have a tag listed in allocation/cling_tag_list that
 * matches a tag of the PV of the existing segment?
 */
static int _pvs_have_matching_tag(const struct dm_config_node *cling_tag_list_cn,
				  struct physical_volume *pv1, struct physical_volume *pv2)
{
	return _match_pv_tags(cling_tag_list_cn, pv1, 0, 0, pv2, NULL, 0, NULL, NULL);
}

static int _has_matching_pv_tag(struct pv_match *pvmatch, struct pv_segment *pvseg, struct pv_area *pva)
{
	return _pvs_have_matching_tag(pvmatch->cling_tag_list_cn, pvseg->pv, pva->map->pv);
}

/*
 * Is PV area contiguous to PV segment?
 */
static int _is_contiguous(struct pv_match *pvmatch __attribute((unused)), struct pv_segment *pvseg, struct pv_area *pva)
{
	if (pvseg->pv != pva->map->pv)
		return 0;

	if (pvseg->pe + pvseg->len != pva->start)
		return 0;

	return 1;
}

static void _reserve_area(struct alloc_handle *ah, struct alloc_state *alloc_state, struct pv_area *pva,
			  uint32_t required, uint32_t ix_pva, uint32_t unreserved)
{
	struct pv_area_used *area_used = &alloc_state->areas[ix_pva];
	const char *pv_tag_list = NULL;

	if (ah->cling_tag_list_cn)
		pv_tag_list = _tags_list_str(ah, pva->map->pv);

	log_debug_alloc("%s allocation area %" PRIu32 " %s %s start PE %" PRIu32
			" length %" PRIu32 " leaving %" PRIu32 "%s%s.",
			area_used->pva ? "Changing   " : "Considering",
			ix_pva, area_used->pva ? "to" : "as",
			dev_name(pva->map->pv->dev), pva->start, required, unreserved,
			pv_tag_list ? " with PV tags: " : "",
			pv_tag_list ? : "");

	if (pv_tag_list)
		dm_pool_free(ah->mem, (void *)pv_tag_list);

	area_used->pva = pva;
	area_used->used = required;
}

static int _reserve_required_area(struct alloc_handle *ah, struct alloc_state *alloc_state, struct pv_area *pva,
				  uint32_t required, uint32_t ix_pva, uint32_t unreserved)
{
	uint32_t s;

	/* Expand areas array if needed after an area was split. */
	if (ix_pva >= alloc_state->areas_size) {
		alloc_state->areas_size *= 2;
		if (!(alloc_state->areas = dm_realloc(alloc_state->areas, sizeof(*alloc_state->areas) * (alloc_state->areas_size)))) {
			log_error("Memory reallocation for parallel areas failed.");
			return 0;
		}
		for (s = alloc_state->areas_size / 2; s < alloc_state->areas_size; s++)
			alloc_state->areas[s].pva = NULL;
	}

	_reserve_area(ah, alloc_state, pva, required, ix_pva, unreserved);

	return 1;
}

static int _is_condition(struct cmd_context *cmd __attribute__((unused)),
			 struct pv_segment *pvseg, uint32_t s,
			 void *data)
{
	struct pv_match *pvmatch = data;
	int positional = pvmatch->alloc_state->alloc_parms->flags & A_POSITIONAL_FILL;

	if (positional && pvmatch->alloc_state->areas[s].pva)
		return 1;	/* Area already assigned */

	if (!pvmatch->condition(pvmatch, pvseg, pvmatch->pva))
		return 1;	/* Continue */

	if (positional && (s >= pvmatch->alloc_state->num_positional_areas))
		return 1;

	/* FIXME The previous test should make this one redundant. */
	if (positional && (s >= pvmatch->alloc_state->areas_size))
		return 1;

	/*
	 * Only used for cling and contiguous policies (which only make one allocation per PV)
	 * so it's safe to say all the available space is used.
	 */
	if (positional)
		_reserve_required_area(pvmatch->ah, pvmatch->alloc_state, pvmatch->pva, pvmatch->pva->count, s, 0);

	return 2;	/* Finished */
}

/*
 * Is pva on same PV as any existing areas?
 */
static int _check_cling(struct alloc_handle *ah,
			const struct dm_config_node *cling_tag_list_cn,
			struct lv_segment *prev_lvseg, struct pv_area *pva,
			struct alloc_state *alloc_state)
{
	struct pv_match pvmatch;
	int r;
	uint32_t le, len;

	pvmatch.ah = ah;
	pvmatch.condition = cling_tag_list_cn ? _has_matching_pv_tag : _is_same_pv;
	pvmatch.alloc_state = alloc_state;
	pvmatch.pva = pva;
	pvmatch.cling_tag_list_cn = cling_tag_list_cn;

	if (ah->maximise_cling) {
		/* Check entire LV */
		le = 0;
		len = prev_lvseg->le + prev_lvseg->len;
	} else {
		/* Only check 1 LE at end of previous LV segment */
		le = prev_lvseg->le + prev_lvseg->len - 1;
		len = 1;
	}

	/* FIXME Cope with stacks by flattening */
	if (!(r = _for_each_pv(ah->cmd, prev_lvseg->lv, le, len, NULL, NULL,
			       0, 0, -1, 1,
			       _is_condition, &pvmatch)))
		stack;

	if (r != 2)
		return 0;

	return 1;
}

/*
 * Is pva contiguous to any existing areas or on the same PV?
 */
static int _check_contiguous(struct alloc_handle *ah,
			     struct lv_segment *prev_lvseg, struct pv_area *pva,
			     struct alloc_state *alloc_state)
{
	struct pv_match pvmatch;
	int r;

	pvmatch.ah = ah;
	pvmatch.condition = _is_contiguous;
	pvmatch.alloc_state = alloc_state;
	pvmatch.pva = pva;
	pvmatch.cling_tag_list_cn = NULL;

	/* FIXME Cope with stacks by flattening */
	if (!(r = _for_each_pv(ah->cmd, prev_lvseg->lv,
			       prev_lvseg->le + prev_lvseg->len - 1, 1, NULL, NULL,
			       0, 0, -1, 1,
			       _is_condition, &pvmatch)))
		stack;

	if (r != 2)
		return 0;

	return 1;
}

/*
 * Is pva on same PV as any areas already used in this allocation attempt?
 */
static int _check_cling_to_alloced(struct alloc_handle *ah, const struct dm_config_node *cling_tag_list_cn,
				   struct pv_area *pva, struct alloc_state *alloc_state)
{
	unsigned s;
	struct alloced_area *aa;
	int positional = alloc_state->alloc_parms->flags & A_POSITIONAL_FILL;

	/*
	 * Ignore log areas.  They are always allocated whole as part of the
	 * first allocation.  If they aren't yet set, we know we've nothing to do.
	 */
	if (alloc_state->log_area_count_still_needed)
		return 0;

	for (s = 0; s < ah->area_count; s++) {
		if (positional && alloc_state->areas[s].pva)
			continue;	/* Area already assigned */
		dm_list_iterate_items(aa, &ah->alloced_areas[s]) {
			if ((!cling_tag_list_cn && (pva->map->pv == aa[0].pv)) ||
			    (cling_tag_list_cn && _pvs_have_matching_tag(cling_tag_list_cn, pva->map->pv, aa[0].pv))) {
				if (positional)
					_reserve_required_area(ah, alloc_state, pva, pva->count, s, 0);
				return 1;
			}
		}
	}

	return 0;
}

static int _pv_is_parallel(struct physical_volume *pv, struct dm_list *parallel_pvs)
{
	struct pv_list *pvl;

	dm_list_iterate_items(pvl, parallel_pvs)
		if (pv == pvl->pv)
			return 1;

	return 0;
}

/*
 * Decide whether or not to try allocation from supplied area pva.
 * alloc_state->areas may get modified.
 */
static area_use_t _check_pva(struct alloc_handle *ah, struct pv_area *pva, uint32_t still_needed,
			     struct alloc_state *alloc_state,
			     unsigned already_found_one, unsigned iteration_count, unsigned log_iteration_count)
{
	const struct alloc_parms *alloc_parms = alloc_state->alloc_parms;
	unsigned s;

	/* Skip fully-reserved areas (which are not currently removed from the list). */
	if (!pva->unreserved)
		return NEXT_AREA;

	/* FIXME Should this test be removed? */
	if (iteration_count)
		/*
		* Don't use an area twice.
		*/
		for (s = 0; s < alloc_state->areas_size; s++)
			if (alloc_state->areas[s].pva == pva)
				return NEXT_AREA;

	/* If maximise_cling is set, perform several checks, otherwise perform exactly one. */
	if (!iteration_count && !log_iteration_count && alloc_parms->flags & (A_CONTIGUOUS_TO_LVSEG | A_CLING_TO_LVSEG | A_CLING_TO_ALLOCED)) {
		/* Contiguous? */
		if (((alloc_parms->flags & A_CONTIGUOUS_TO_LVSEG) ||
		     (ah->maximise_cling && (alloc_parms->flags & A_AREA_COUNT_MATCHES))) &&
		    _check_contiguous(ah, alloc_parms->prev_lvseg, pva, alloc_state))
			goto found;

		/* Try next area on same PV if looking for contiguous space */
		if (alloc_parms->flags & A_CONTIGUOUS_TO_LVSEG)
			return NEXT_AREA;

		/* Cling to prev_lvseg? */
		if (((alloc_parms->flags & A_CLING_TO_LVSEG) ||
		     (ah->maximise_cling && (alloc_parms->flags & A_AREA_COUNT_MATCHES))) &&
		    _check_cling(ah, NULL, alloc_parms->prev_lvseg, pva, alloc_state))
			/* If this PV is suitable, use this first area */
			goto found;

		/* Cling_to_alloced? */
		if ((alloc_parms->flags & A_CLING_TO_ALLOCED) &&
		    _check_cling_to_alloced(ah, NULL, pva, alloc_state))
			goto found;

		/* Cling_by_tags? */
		if (!(alloc_parms->flags & A_CLING_BY_TAGS) || !ah->cling_tag_list_cn)
			return NEXT_PV;

		if ((alloc_parms->flags & A_AREA_COUNT_MATCHES)) {
			if (_check_cling(ah, ah->cling_tag_list_cn, alloc_parms->prev_lvseg, pva, alloc_state))
				goto found;
		} else if (_check_cling_to_alloced(ah, ah->cling_tag_list_cn, pva, alloc_state))
			goto found;

		/* All areas on this PV give same result so pointless checking more */
		return NEXT_PV;
	}

	/* Normal/Anywhere */

	/* Is it big enough on its own? */
	if (pva->unreserved * ah->area_multiple < still_needed &&
	    ((!(alloc_parms->flags & A_CAN_SPLIT) && !ah->log_area_count) ||
	     (already_found_one && alloc_parms->alloc != ALLOC_ANYWHERE)))
		return NEXT_PV;

found:
	if (alloc_parms->flags & A_POSITIONAL_FILL)
		return PREFERRED;

	return USE_AREA;
}

/*
 * Decide how many extents we're trying to obtain from a given area.
 * Removes the extents from further consideration.
 */
static uint32_t _calc_required_extents(struct alloc_handle *ah, struct pv_area *pva, unsigned ix_pva, uint32_t max_to_allocate, alloc_policy_t alloc)
{
	uint32_t required = max_to_allocate / ah->area_multiple;

	/*
	 * Update amount unreserved - effectively splitting an area
	 * into two or more parts.  If the whole stripe doesn't fit,
	 * reduce amount we're looking for.
	 */
	if (alloc == ALLOC_ANYWHERE) {
		if (ix_pva >= ah->area_count + ah->parity_count)
			required = ah->log_len;
	} else if (required < ah->log_len)
		required = ah->log_len;

	if (required >= pva->unreserved) {
		required = pva->unreserved;
		pva->unreserved = 0;
	} else {
		pva->unreserved -= required;
		reinsert_changed_pv_area(pva);
	}

	return required;
}

static void _clear_areas(struct alloc_state *alloc_state)
{
	uint32_t s;

	alloc_state->num_positional_areas = 0;

	for (s = 0; s < alloc_state->areas_size; s++)
		alloc_state->areas[s].pva = NULL;
}

static void _reset_unreserved(struct dm_list *pvms)
{
	struct pv_map *pvm;
	struct pv_area *pva;

	dm_list_iterate_items(pvm, pvms)
		dm_list_iterate_items(pva, &pvm->areas)
			if (pva->unreserved != pva->count) {
				pva->unreserved = pva->count;
				reinsert_changed_pv_area(pva);
			}
}

static void _report_needed_allocation_space(struct alloc_handle *ah,
					    struct alloc_state *alloc_state,
					    struct dm_list *pvms)
{
	const char *metadata_type;
	uint32_t parallel_areas_count, parallel_area_size;
	uint32_t metadata_count, metadata_size;

	parallel_area_size = ah->new_extents - alloc_state->allocated;
	parallel_area_size /= ah->area_multiple;
	parallel_area_size -= (ah->alloc_and_split_meta && !ah->split_metadata_is_allocated) ? ah->log_len : 0;

	parallel_areas_count = ah->area_count + ah->parity_count;

	metadata_size = ah->log_len;
	if (ah->alloc_and_split_meta) {
		metadata_type = "metadata area";
		metadata_count = parallel_areas_count;
		if (ah->split_metadata_is_allocated)
			metadata_size = 0;
	} else {
		metadata_type = "mirror log";
		metadata_count = alloc_state->log_area_count_still_needed;
	}

	log_debug_alloc("Still need %s%" PRIu32 " total extents from %" PRIu32 " remaining (%" PRIu32 " positional slots):",
			ah->approx_alloc ? "up to " : "",
			parallel_area_size * parallel_areas_count + metadata_size * metadata_count, pv_maps_size(pvms),
			alloc_state->num_positional_areas);
	log_debug_alloc("  %" PRIu32 " (%" PRIu32 " data/%" PRIu32
			" parity) parallel areas of %" PRIu32 " extents each",
			parallel_areas_count, ah->area_count, ah->parity_count, parallel_area_size);
	log_debug_alloc("  %" PRIu32 " %s%s of %" PRIu32 " extents each",
			metadata_count, metadata_type,
			(metadata_count == 1) ? "" : "s",
			metadata_size);
}

/* Work through the array, removing any entries with tags already used by previous areas. */
static int _limit_to_one_area_per_tag(struct alloc_handle *ah, struct alloc_state *alloc_state,
				      uint32_t ix_log_offset, unsigned *ix)
{
	uint32_t	s = 0, u = 0;
	DM_LIST_INIT(pv_tags);

	while (s < alloc_state->areas_size && alloc_state->areas[s].pva) {
		/* Start again with an empty tag list when we reach the log devices */
		if (u == ix_log_offset)
			dm_list_init(&pv_tags);
		if (!_pv_has_matching_tag(ah->cling_tag_list_cn, alloc_state->areas[s].pva->map->pv, alloc_state->areas[s].pva->start, s, &pv_tags)) {
			/* The comparison fn will ignore any non-cling tags so just add everything */
			if (!str_list_add_list(ah->mem, &pv_tags, &alloc_state->areas[s].pva->map->pv->tags))
				return_0;

			if (s != u)
				alloc_state->areas[u] = alloc_state->areas[s];

			u++;
		} else
			(*ix)--;	/* One area removed */

		s++;
	}

	alloc_state->areas[u].pva = NULL;

	return 1;
}

/*
 * Returns 1 regardless of whether any space was found, except on error.
 */
static int _find_some_parallel_space(struct alloc_handle *ah,
				     struct dm_list *pvms, struct alloc_state *alloc_state,
				     struct dm_list *parallel_pvs, uint32_t max_to_allocate)
{
	const struct alloc_parms *alloc_parms = alloc_state->alloc_parms;
	unsigned ix = 0;
	unsigned last_ix;
	struct pv_map *pvm;
	struct pv_area *pva;
	unsigned preferred_count = 0;
	unsigned already_found_one;
	unsigned ix_log_offset; /* Offset to start of areas to use for log */
	unsigned too_small_for_log_count; /* How many too small for log? */
	unsigned iteration_count = 0; /* cling_to_alloced may need 2 iterations */
	unsigned log_iteration_count = 0; /* extra iteration for logs on data devices */
	struct alloced_area *aa;
	uint32_t s;
	uint32_t devices_needed = ah->area_count + ah->parity_count;
	uint32_t required;

	_clear_areas(alloc_state);
	_reset_unreserved(pvms);

	/* num_positional_areas holds the number of parallel allocations that must be contiguous/cling */
	/* These appear first in the array, so it is also the offset to the non-preferred allocations */
	/* At most one of A_CONTIGUOUS_TO_LVSEG, A_CLING_TO_LVSEG or A_CLING_TO_ALLOCED may be set */
	if (!(alloc_parms->flags & A_POSITIONAL_FILL))
		alloc_state->num_positional_areas = 0;
	else if (alloc_parms->flags & (A_CONTIGUOUS_TO_LVSEG | A_CLING_TO_LVSEG))
		alloc_state->num_positional_areas = _stripes_per_mimage(alloc_parms->prev_lvseg) * alloc_parms->prev_lvseg->area_count;
	else if (alloc_parms->flags & A_CLING_TO_ALLOCED)
		alloc_state->num_positional_areas = ah->area_count;

	if (alloc_parms->alloc == ALLOC_NORMAL || (alloc_parms->flags & A_CLING_TO_ALLOCED))
		log_debug_alloc("Cling_to_allocated is %sset",
				alloc_parms->flags & A_CLING_TO_ALLOCED ? "" : "not ");

	if (alloc_parms->flags & A_POSITIONAL_FILL)
		log_debug_alloc("%u preferred area(s) to be filled positionally.", alloc_state->num_positional_areas);
	else
		log_debug_alloc("Areas to be sorted and filled sequentially.");

	_report_needed_allocation_space(ah, alloc_state, pvms);

	/* ix holds the number of areas found on other PVs */
	do {
		if (log_iteration_count) {
			log_debug_alloc("Found %u areas for %" PRIu32 " parallel areas and %" PRIu32 " log areas so far.", ix, devices_needed, alloc_state->log_area_count_still_needed);
		} else if (iteration_count)
			log_debug_alloc("Filled %u out of %u preferred areas so far.", preferred_count, alloc_state->num_positional_areas);

		/*
		 * Provide for escape from the loop if no progress is made.
		 * This should not happen: ALLOC_ANYWHERE should be able to use
		 * all available space. (If there aren't enough extents, the code
		 * should not reach this point.)
		 */
		last_ix = ix;

		/*
		 * Put the smallest area of each PV that is at least the
		 * size we need into areas array.  If there isn't one
		 * that fits completely and we're allowed more than one
		 * LV segment, then take the largest remaining instead.
		 */
		dm_list_iterate_items(pvm, pvms) {
			/* PV-level checks */
			if (dm_list_empty(&pvm->areas))
				continue;	/* Next PV */

			if (alloc_parms->alloc != ALLOC_ANYWHERE) {
				/* Don't allocate onto the log PVs */
				if (ah->log_area_count)
					dm_list_iterate_items(aa, &ah->alloced_areas[ah->area_count])
						for (s = 0; s < ah->log_area_count; s++)
							if (!aa[s].pv)
								goto next_pv;

				/* FIXME Split into log and non-log parallel_pvs and only check the log ones if log_iteration? */
				/* (I've temporatily disabled the check.) */
				/* Avoid PVs used by existing parallel areas */
				if (!log_iteration_count && parallel_pvs && _pv_is_parallel(pvm->pv, parallel_pvs))
					goto next_pv;

				/*
				 * Avoid PVs already set aside for log.
				 * We only reach here if there were enough PVs for the main areas but
				 * not enough for the logs.
				 */
				if (log_iteration_count) {
					for (s = devices_needed; s < ix + alloc_state->num_positional_areas; s++)
						if (alloc_state->areas[s].pva && alloc_state->areas[s].pva->map->pv == pvm->pv)
							goto next_pv;
				/* On a second pass, avoid PVs already used in an uncommitted area */
				} else if (iteration_count)
					for (s = 0; s < devices_needed; s++)
						if (alloc_state->areas[s].pva && alloc_state->areas[s].pva->map->pv == pvm->pv)
							goto next_pv;
			}

			already_found_one = 0;
			/* First area in each list is the largest */
			dm_list_iterate_items(pva, &pvm->areas) {
				/*
				 * There are two types of allocations, which can't be mixed at present:
				 *
				 * PREFERRED are stored immediately in a specific parallel slot.
				 *   This is only used if the A_POSITIONAL_FILL flag is set.
				 *   This requires the number of slots to match, so if comparing with
				 *   prev_lvseg then A_AREA_COUNT_MATCHES must be set.
				 *
				 * USE_AREA are stored for later, then sorted and chosen from.
				 */
				switch(_check_pva(ah, pva, max_to_allocate,
						  alloc_state, already_found_one, iteration_count, log_iteration_count)) {

				case PREFERRED:
					preferred_count++;
					/* Fall through */

				case NEXT_PV:
					goto next_pv;

				case NEXT_AREA:
					continue;

				case USE_AREA:
					/*
					 * Except with ALLOC_ANYWHERE, replace first area with this
					 * one which is smaller but still big enough.
					 */
					if (!already_found_one ||
					    alloc_parms->alloc == ALLOC_ANYWHERE) {
						ix++;
						already_found_one = 1;
					}

					/* Reserve required amount of pva */
					required = _calc_required_extents(ah, pva, ix + alloc_state->num_positional_areas - 1, max_to_allocate, alloc_parms->alloc);
					if (!_reserve_required_area(ah, alloc_state, pva, required, ix + alloc_state->num_positional_areas - 1, pva->unreserved))
						return_0;
				}

			}

		next_pv:
			/* With ALLOC_ANYWHERE we ignore further PVs once we have at least enough areas */
			/* With cling and contiguous we stop if we found a match for *all* the areas */
			/* FIXME Rename these variables! */
			if ((alloc_parms->alloc == ALLOC_ANYWHERE &&
			    ix + alloc_state->num_positional_areas >= devices_needed + alloc_state->log_area_count_still_needed) ||
			    (preferred_count == alloc_state->num_positional_areas &&
			     (alloc_state->num_positional_areas == devices_needed + alloc_state->log_area_count_still_needed)))
				break;
		}
	} while ((alloc_parms->alloc == ALLOC_ANYWHERE && last_ix != ix && ix < devices_needed + alloc_state->log_area_count_still_needed) ||
		/* With cling_to_alloced and normal, if there were gaps in the preferred areas, have a second iteration */
		 (alloc_parms->alloc == ALLOC_NORMAL && preferred_count &&
		  (preferred_count < alloc_state->num_positional_areas || alloc_state->log_area_count_still_needed) &&
		  (alloc_parms->flags & A_CLING_TO_ALLOCED) && !iteration_count++) ||
		/* Extra iteration needed to fill log areas on PVs already used? */
		 (alloc_parms->alloc == ALLOC_NORMAL && preferred_count == alloc_state->num_positional_areas && !ah->mirror_logs_separate &&
		  (ix + preferred_count >= devices_needed) &&
		  (ix + preferred_count < devices_needed + alloc_state->log_area_count_still_needed) && !log_iteration_count++));

	/* Non-zero ix means at least one USE_AREA was returned */
	if (preferred_count < alloc_state->num_positional_areas && !(alloc_parms->flags & A_CLING_TO_ALLOCED) && !ix)
		return 1;

	if (ix + preferred_count < devices_needed + alloc_state->log_area_count_still_needed)
		return 1;

	/* Sort the areas so we allocate from the biggest */
	if (log_iteration_count) {
		if (ix > devices_needed + 1) {
			log_debug_alloc("Sorting %u log areas", ix - devices_needed);
			qsort(alloc_state->areas + devices_needed, ix - devices_needed, sizeof(*alloc_state->areas),
			      _comp_area);
		}
	} else if (ix > 1) {
		log_debug_alloc("Sorting %u areas", ix);
		qsort(alloc_state->areas + alloc_state->num_positional_areas, ix, sizeof(*alloc_state->areas),
		      _comp_area);
	}

	/* If there are gaps in our preferred areas, fill them from the sorted part of the array */
	if (preferred_count && preferred_count != alloc_state->num_positional_areas) {
		for (s = 0; s < devices_needed; s++)
			if (!alloc_state->areas[s].pva) {
				alloc_state->areas[s].pva = alloc_state->areas[alloc_state->num_positional_areas].pva;
				alloc_state->areas[s].used = alloc_state->areas[alloc_state->num_positional_areas].used;
				alloc_state->areas[alloc_state->num_positional_areas++].pva = NULL;
			}
	}

	/*
	 * First time around, if there's a log, allocate it on the
	 * smallest device that has space for it.
	 */
	too_small_for_log_count = 0;
	ix_log_offset = 0;

	/* FIXME This logic is due to its heritage and can be simplified! */
	if (alloc_state->log_area_count_still_needed) {
		/* How many areas are too small for the log? */
		while (too_small_for_log_count < alloc_state->num_positional_areas + ix &&
		       (*(alloc_state->areas + alloc_state->num_positional_areas + ix - 1 -
			  too_small_for_log_count)).used < ah->log_len)
			too_small_for_log_count++;
		ix_log_offset = alloc_state->num_positional_areas + ix - too_small_for_log_count - ah->log_area_count;
	}

	if (ix + alloc_state->num_positional_areas < devices_needed +
	    (alloc_state->log_area_count_still_needed ? alloc_state->log_area_count_still_needed +
				    too_small_for_log_count : 0))
		return 1;

	/*
	 * FIXME We should change the code to do separate calls for the log allocation
	 * and the data allocation so that _limit_to_one_area_per_tag doesn't have to guess
	 * where the split is going to occur.
	 */

	/*
	 * This code covers the initial allocation - after that there is something to 'cling' to
	 * and we shouldn't get this far.
	 * alloc_state->num_positional_areas is assumed to be 0 with A_PARTITION_BY_TAGS.
	 *
	 * FIXME Consider a second attempt with A_PARTITION_BY_TAGS if, for example, the largest area
	 * had all the tags set, but other areas don't.
	 */
	if ((alloc_parms->flags & A_PARTITION_BY_TAGS) && !alloc_state->num_positional_areas) {
		if (!_limit_to_one_area_per_tag(ah, alloc_state, ix_log_offset, &ix))
			return_0;

		/* Recalculate log position because we might have removed some areas from consideration */
		if (alloc_state->log_area_count_still_needed) {
			/* How many areas are too small for the log? */
			too_small_for_log_count = 0;
			while (too_small_for_log_count < ix &&
			       (*(alloc_state->areas + ix - 1 - too_small_for_log_count)).pva &&
			       (*(alloc_state->areas + ix - 1 - too_small_for_log_count)).used < ah->log_len)
				too_small_for_log_count++;
			if (ix < too_small_for_log_count + ah->log_area_count)
				return 1;
			ix_log_offset = ix - too_small_for_log_count - ah->log_area_count;
		}

		if (ix < devices_needed +
		    (alloc_state->log_area_count_still_needed ? alloc_state->log_area_count_still_needed +
					    too_small_for_log_count : 0))
			return 1;
	}

	/*
	 * Finally add the space identified to the list of areas to be used.
	 */
	if (!_alloc_parallel_area(ah, max_to_allocate, alloc_state, ix_log_offset))
		return_0;

	/*
	 * Log is always allocated first time.
	 */
	alloc_state->log_area_count_still_needed = 0;

	return 1;
}

/*
 * Choose sets of parallel areas to use, respecting any constraints
 * supplied in alloc_parms.
 */
static int _find_max_parallel_space_for_one_policy(struct alloc_handle *ah, struct alloc_parms *alloc_parms,
						   struct dm_list *pvms, struct alloc_state *alloc_state)
{
	uint32_t max_tmp;
	uint32_t max_to_allocate;	/* Maximum extents to allocate this time */
	uint32_t old_allocated;
	uint32_t next_le;
	struct seg_pvs *spvs;
	struct dm_list *parallel_pvs;

	alloc_state->alloc_parms = alloc_parms;

	/* FIXME This algorithm needs a lot of cleaning up! */
	/* FIXME anywhere doesn't find all space yet */
	do {
		parallel_pvs = NULL;
		max_to_allocate = alloc_parms->extents_still_needed - alloc_state->allocated;

		/*
		 * If there are existing parallel PVs, avoid them and reduce
		 * the maximum we can allocate in one go accordingly.
		 */
		if (ah->parallel_areas) {
			next_le = (alloc_parms->prev_lvseg ? alloc_parms->prev_lvseg->le + alloc_parms->prev_lvseg->len : 0) + alloc_state->allocated / ah->area_multiple;
			dm_list_iterate_items(spvs, ah->parallel_areas) {
				if (next_le >= spvs->le + spvs->len)
					continue;

				max_tmp = max_to_allocate +
					alloc_state->allocated;

				/*
				 * Because a request that groups metadata and
				 * data together will be split, we must adjust
				 * the comparison accordingly.
				 */
				if (ah->alloc_and_split_meta && !ah->split_metadata_is_allocated)
					max_tmp -= ah->log_len;
				if (max_tmp > (spvs->le + spvs->len) * ah->area_multiple) {
					max_to_allocate = (spvs->le + spvs->len) * ah->area_multiple - alloc_state->allocated;
					max_to_allocate += (ah->alloc_and_split_meta && !ah->split_metadata_is_allocated) ? ah->log_len : 0;
				}
				parallel_pvs = &spvs->pvs;
				break;
			}
		}

		old_allocated = alloc_state->allocated;

		if (!_find_some_parallel_space(ah, pvms, alloc_state, parallel_pvs, max_to_allocate))
			return_0;

		/*
		 * For ALLOC_CLING, if the number of areas matches and maximise_cling is
		 * set we allow two passes, first with A_POSITIONAL_FILL then without.
		 *
		 * If we didn't allocate anything this time with ALLOC_NORMAL and had
		 * A_CLING_TO_ALLOCED set, try again without it.
		 *
		 * For ALLOC_NORMAL, if we did allocate something without the
		 * flag set, set it and continue so that further allocations
		 * remain on the same disks where possible.
		 */
		if (old_allocated == alloc_state->allocated) {
			if (ah->maximise_cling && ((alloc_parms->alloc == ALLOC_CLING) || (alloc_parms->alloc == ALLOC_CLING_BY_TAGS)) &&
			    (alloc_parms->flags & A_CLING_TO_LVSEG) && (alloc_parms->flags & A_POSITIONAL_FILL))
				alloc_parms->flags &= ~A_POSITIONAL_FILL;
			else if ((alloc_parms->alloc == ALLOC_NORMAL) && (alloc_parms->flags & A_CLING_TO_ALLOCED))
				alloc_parms->flags &= ~A_CLING_TO_ALLOCED;
			else
				break;	/* Give up */
		} else if (ah->maximise_cling && alloc_parms->alloc == ALLOC_NORMAL &&