/*-
 *   BSD LICENSE
 *
 *   Copyright (c) Intel Corporation.
 *   All rights reserved.
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *     * Neither the name of Intel Corporation nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "spdk/likely.h"
#include "spdk_internal/log.h"
#include "spdk/ftl.h"

#include "ftl_reloc.h"
#include "ftl_core.h"
#include "ftl_io.h"
#include "ftl_rwb.h"
#include "ftl_band.h"
#include "ftl_debug.h"

/* Maximum active reloc moves */
#define FTL_RELOC_MAX_MOVES 256

struct ftl_reloc;
struct ftl_band_reloc;

enum ftl_reloc_move_state {
	FTL_RELOC_STATE_READ_LBA_MAP,
	FTL_RELOC_STATE_READ,
	FTL_RELOC_STATE_WRITE,
};

struct ftl_reloc_move {
	struct ftl_band_reloc			*breloc;

	/* Start ppa */
	struct ftl_ppa				ppa;

	/* Number of logical blocks */
	size_t					lbk_cnt;

	/* Data buffer */
	void					*data;

	/* Move state (read lba_map, read, write) */
	enum ftl_reloc_move_state		state;

	/* IO associated with move */
	struct ftl_io				*io;
};

struct ftl_band_reloc {
	struct ftl_reloc			*parent;

	/* Band being relocated */
	struct ftl_band				*band;

	/* Number of logical blocks to be relocated */
	size_t					num_lbks;

	/* Bitmap of logical blocks to be relocated */
	struct spdk_bit_array			*reloc_map;

	/* Indicates band being acitvely processed */
	int					active;
	/* The band is being defragged */
	bool					defrag;

	/* Reloc map iterator */
	struct {
		/* Array of chunk offsets */
		size_t				*chk_offset;

		/* Currently chunk */
		size_t				chk_current;
	} iter;

	/* Number of outstanding moves */
	size_t					num_outstanding;

	/* Pool of move objects */
	struct ftl_reloc_move			*moves;

	/* Move queue */
	struct spdk_ring			*move_queue;

	TAILQ_ENTRY(ftl_band_reloc)		entry;
};

struct ftl_reloc {
	/* Device associated with relocate */
	struct spdk_ftl_dev			*dev;

	/* Indicates relocate is about to halt */
	bool					halt;

	/* Maximum number of IOs per band */
	size_t					max_qdepth;

	/* Maximum number of active band relocates */
	size_t					max_active;

	/* Maximum transfer size (in logical blocks) per single IO */
	size_t					xfer_size;
	/* Number of bands being defragged */
	size_t					num_defrag_bands;

	/* Array of band relocates */
	struct ftl_band_reloc			*brelocs;

	/* Number of active/priority band relocates */
	size_t					num_active;

	/* Priority band relocates queue */
	TAILQ_HEAD(, ftl_band_reloc)		prio_queue;

	/* Active band relocates queue */
	TAILQ_HEAD(, ftl_band_reloc)		active_queue;

	/* Pending band relocates queue */
	TAILQ_HEAD(, ftl_band_reloc)		pending_queue;
};

bool
ftl_reloc_is_defrag_active(const struct ftl_reloc *reloc)
{
	return reloc->num_defrag_bands > 0;
}

static size_t
ftl_reloc_iter_chk_offset(struct ftl_band_reloc *breloc)
{
	size_t chunk = breloc->iter.chk_current;

	return breloc->iter.chk_offset[chunk];
}

static size_t
ftl_reloc_iter_chk_done(struct ftl_band_reloc *breloc)
{
	size_t num_lbks = ftl_dev_lbks_in_chunk(breloc->parent->dev);

	return ftl_reloc_iter_chk_offset(breloc) == num_lbks;
}

static void
ftl_reloc_clr_lbk(struct ftl_band_reloc *breloc, size_t lbkoff)
{
	if (!spdk_bit_array_get(breloc->reloc_map, lbkoff)) {
		return;
	}

	spdk_bit_array_clear(breloc->reloc_map, lbkoff);
	assert(breloc->num_lbks);
	breloc->num_lbks--;
}

static void
ftl_reloc_read_lba_map_cb(struct ftl_io *io, void *arg, int status)
{
	struct ftl_reloc_move *move = arg;
	struct ftl_band_reloc *breloc = move->breloc;

	breloc->num_outstanding--;
	assert(status == 0);
	move->state = FTL_RELOC_STATE_WRITE;
	spdk_ring_enqueue(breloc->move_queue, (void **)&move, 1, NULL);
}

static int
ftl_reloc_read_lba_map(struct ftl_band_reloc *breloc, struct ftl_reloc_move *move)
{
	struct ftl_band *band = breloc->band;

	breloc->num_outstanding++;
	return ftl_band_read_lba_map(band, ftl_band_lbkoff_from_ppa(band, move->ppa),
				     move->lbk_cnt, ftl_reloc_read_lba_map_cb, move);
}

static void
ftl_reloc_prep(struct ftl_band_reloc *breloc)
{
	struct ftl_band *band = breloc->band;
	struct ftl_reloc *reloc = breloc->parent;
	struct ftl_reloc_move *move;
	size_t i;

	breloc->active = 1;
	reloc->num_active++;

	if (!band->high_prio) {
		if (band->lba_map.ref_cnt == 0) {
			if (ftl_band_alloc_lba_map(band)) {
				assert(false);
			}
		} else {
			ftl_band_acquire_lba_map(band);
		}
	}

	for (i = 0; i < reloc->max_qdepth; ++i) {
		move = &breloc->moves[i];
		move->state = FTL_RELOC_STATE_READ;
		spdk_ring_enqueue(breloc->move_queue, (void **)&move, 1, NULL);
	}
}

static void
ftl_reloc_free_move(struct ftl_band_reloc *breloc, struct ftl_reloc_move *move)
{
	assert(move);
	spdk_dma_free(move->data);
	memset(move, 0, sizeof(*move));
	move->state = FTL_RELOC_STATE_READ;
	spdk_ring_enqueue(breloc->move_queue, (void **)&move, 1, NULL);
}

static void
ftl_reloc_write_cb(struct ftl_io *io, void *arg, int status)
{
	struct ftl_reloc_move *move = arg;
	struct ftl_ppa ppa = move->ppa;
	struct ftl_band_reloc *breloc = move->breloc;
	size_t i;

	breloc->num_outstanding--;

	if (status) {
		SPDK_ERRLOG("Reloc write failed with status: %d\n", status);
		assert(false);
		return;
	}

	for (i = 0; i < move->lbk_cnt; ++i) {
		ppa.lbk = move->ppa.lbk + i;
		size_t lbkoff = ftl_band_lbkoff_from_ppa(breloc->band, ppa);
		ftl_reloc_clr_lbk(breloc, lbkoff);
	}

	ftl_reloc_free_move(breloc, move);
}

static void
ftl_reloc_read_cb(struct ftl_io *io, void *arg, int status)
{
	struct ftl_reloc_move *move = arg;
	struct ftl_band_reloc *breloc = move->breloc;

	breloc->num_outstanding--;

	/* TODO: We should handle fail on relocation read. We need to inform */
	/* user that this group of blocks is bad (update l2p with bad block address and */
	/* put it to lba_map/sector_lba). Maybe we could also retry read with smaller granularity? */
	if (status) {
		SPDK_ERRLOG("Reloc read failed with status: %d\n", status);
		assert(false);
		return;
	}

	move->state = FTL_RELOC_STATE_READ_LBA_MAP;
	move->io = NULL;
	spdk_ring_enqueue(breloc->move_queue, (void **)&move, 1, NULL);
}

static void
ftl_reloc_iter_reset(struct ftl_band_reloc *breloc)
{
	memset(breloc->iter.chk_offset, 0, ftl_dev_num_punits(breloc->band->dev) *
	       sizeof(*breloc->iter.chk_offset));
	breloc->iter.chk_current = 0;
}

static size_t
ftl_reloc_iter_lbkoff(struct ftl_band_reloc *breloc)
{
	size_t chk_offset = breloc->iter.chk_current * ftl_dev_lbks_in_chunk(breloc->parent->dev);

	return breloc->iter.chk_offset[breloc->iter.chk_current] + chk_offset;
}

static void
ftl_reloc_iter_next_chk(struct ftl_band_reloc *breloc)
{
	size_t num_chk = ftl_dev_num_punits(breloc->band->dev);

	breloc->iter.chk_current = (breloc->iter.chk_current + 1) % num_chk;
}

static int
ftl_reloc_lbk_valid(struct ftl_band_reloc *breloc, size_t lbkoff)
{
	struct ftl_ppa ppa = ftl_band_ppa_from_lbkoff(breloc->band, lbkoff);

	return ftl_ppa_is_written(breloc->band, ppa) &&
	       spdk_bit_array_get(breloc->reloc_map, lbkoff) &&
	       ftl_band_lbkoff_valid(breloc->band, lbkoff);
}

static int
ftl_reloc_iter_next(struct ftl_band_reloc *breloc, size_t *lbkoff)
{
	size_t chunk = breloc->iter.chk_current;

	*lbkoff = ftl_reloc_iter_lbkoff(breloc);

	if (ftl_reloc_iter_chk_done(breloc)) {
		return 0;
	}

	breloc->iter.chk_offset[chunk]++;

	if (!ftl_reloc_lbk_valid(breloc, *lbkoff)) {
		ftl_reloc_clr_lbk(breloc, *lbkoff);
		return 0;
	}

	return 1;
}

static int
ftl_reloc_first_valid_lbk(struct ftl_band_reloc *breloc, size_t *lbkoff)
{
	size_t i, num_lbks = ftl_dev_lbks_in_chunk(breloc->parent->dev);

	for (i = ftl_reloc_iter_chk_offset(breloc); i < num_lbks; ++i) {
		if (ftl_reloc_iter_next(breloc, lbkoff)) {
			return 1;
		}
	}

	return 0;
}

static int
ftl_reloc_iter_done(struct ftl_band_reloc *breloc)
{
	size_t i;
	size_t num_chks = ftl_dev_num_punits(breloc->band->dev);
	size_t num_lbks = ftl_dev_lbks_in_chunk(breloc->parent->dev);

	for (i = 0; i < num_chks; ++i) {
		if (breloc->iter.chk_offset[i] != num_lbks) {
			return 0;
		}
	}

	return 1;
}

static size_t
ftl_reloc_find_valid_lbks(struct ftl_band_reloc *breloc,
			  size_t num_lbk, struct ftl_ppa *ppa)
{
	size_t lbkoff, lbk_cnt = 0;

	if (!ftl_reloc_first_valid_lbk(breloc, &lbkoff)) {
		return 0;
	}

	*ppa = ftl_band_ppa_from_lbkoff(breloc->band, lbkoff);

	for (lbk_cnt = 1; lbk_cnt < num_lbk; lbk_cnt++) {
		if (!ftl_reloc_iter_next(breloc, &lbkoff)) {
			break;
		}
	}

	return lbk_cnt;
}

static size_t
ftl_reloc_next_lbks(struct ftl_band_reloc *breloc, struct ftl_ppa *ppa)
{
	size_t i, lbk_cnt = 0;
	struct spdk_ftl_dev *dev = breloc->parent->dev;

	for (i = 0; i < ftl_dev_num_punits(dev); ++i) {
		lbk_cnt = ftl_reloc_find_valid_lbks(breloc, breloc->parent->xfer_size, ppa);
		ftl_reloc_iter_next_chk(breloc);

		if (lbk_cnt || ftl_reloc_iter_done(breloc)) {
			break;
		}
	}

	return lbk_cnt;
}

static struct ftl_io *
ftl_reloc_io_init(struct ftl_band_reloc *breloc, struct ftl_reloc_move *move,
		  ftl_io_fn fn, enum ftl_io_type io_type, int flags)
{
	size_t lbkoff, i;
	struct ftl_ppa ppa = move->ppa;
	struct ftl_io *io = NULL;
	struct ftl_io_init_opts opts = {
		.dev		= breloc->parent->dev,
		.band		= breloc->band,
		.size		= sizeof(*io),
		.flags		= flags | FTL_IO_INTERNAL | FTL_IO_PPA_MODE,
		.type		= io_type,
		.lbk_cnt	= move->lbk_cnt,
		.data		= move->data,
		.cb_fn		= fn,
	};

	io = ftl_io_init_internal(&opts);
	if (!io) {
		return NULL;
	}

	io->cb_ctx = move;
	io->ppa = move->ppa;

	if (flags & FTL_IO_VECTOR_LBA) {
		for (i = 0; i < io->lbk_cnt; ++i, ++ppa.lbk) {
			lbkoff = ftl_band_lbkoff_from_ppa(breloc->band, ppa);

			if (!ftl_band_lbkoff_valid(breloc->band, lbkoff)) {
				io->lba.vector[i] = FTL_LBA_INVALID;
				continue;
			}

			io->lba.vector[i] = breloc->band->lba_map.map[lbkoff];
		}
	}

	ftl_trace_lba_io_init(io->dev, io);

	return io;
}

static int
ftl_reloc_write(struct ftl_band_reloc *breloc, struct ftl_reloc_move *move)
{
	int io_flags =  FTL_IO_WEAK | FTL_IO_VECTOR_LBA | FTL_IO_BYPASS_CACHE;

	if (spdk_likely(!move->io)) {
		move->io = ftl_reloc_io_init(breloc, move, ftl_reloc_write_cb,
					     FTL_IO_WRITE, io_flags);
		if (!move->io) {
			ftl_reloc_free_move(breloc, move);
			return -ENOMEM;
		}
	}

	breloc->num_outstanding++;
	ftl_io_write(move->io);
	return 0;
}

static int
ftl_reloc_read(struct ftl_band_reloc *breloc, struct ftl_reloc_move *move)
{
	struct ftl_ppa ppa = {};

	move->lbk_cnt = ftl_reloc_next_lbks(breloc, &ppa);
	move->breloc = breloc;
	move->ppa = ppa;

	if (!move->lbk_cnt) {
		return 0;
	}

	move->data = spdk_dma_malloc(FTL_BLOCK_SIZE * move->lbk_cnt, 4096, NULL);
	if (!move->data) {
		return -1;
	}

	move->io = ftl_reloc_io_init(breloc, move, ftl_reloc_read_cb, FTL_IO_READ, 0);
	if (!move->io) {
		ftl_reloc_free_move(breloc, move);
		SPDK_ERRLOG("Failed to initialize io for relocation.");
		return -1;
	}

	breloc->num_outstanding++;
	ftl_io_read(move->io);
	return 0;
}

static void
ftl_reloc_process_moves(struct ftl_band_reloc *breloc)
{
	int rc = 0;
	size_t i, num_moves;
	struct ftl_reloc_move *moves[FTL_RELOC_MAX_MOVES] = {0};
	struct ftl_reloc *reloc = breloc->parent;
	struct ftl_reloc_move *move;

	num_moves = spdk_ring_dequeue(breloc->move_queue, (void **)moves, reloc->max_qdepth);

	for (i = 0; i < num_moves; ++i) {
		move = moves[i];
		assert(move != NULL);
		switch (move->state) {
		case FTL_RELOC_STATE_READ_LBA_MAP:
			rc = ftl_reloc_read_lba_map(breloc, move);
			break;
		case FTL_RELOC_STATE_READ:
			rc = ftl_reloc_read(breloc, move);
			break;
		case FTL_RELOC_STATE_WRITE:
			rc = ftl_reloc_write(breloc, move);
			break;
		default:
			assert(false);
			break;
		}

		if (rc) {
			SPDK_ERRLOG("Move queue processing failed\n");
			assert(false);
		}
	}
}

static bool
ftl_reloc_done(struct ftl_band_reloc *breloc)
{
	return !breloc->num_outstanding && !spdk_ring_count(breloc->move_queue);
}

static void
ftl_reloc_release(struct ftl_band_reloc *breloc)
{
	struct ftl_reloc *reloc = breloc->parent;
	struct ftl_band *band = breloc->band;

	if (band->high_prio && breloc->num_lbks == 0) {
		band->high_prio = 0;
		TAILQ_REMOVE(&reloc->prio_queue, breloc, entry);
	} else if (!band->high_prio) {
		TAILQ_REMOVE(&reloc->active_queue, breloc, entry);
	}

	ftl_reloc_iter_reset(breloc);

	ftl_band_release_lba_map(band);

	breloc->active = 0;
	reloc->num_active--;

	if (!band->high_prio && breloc->num_lbks) {
		TAILQ_INSERT_TAIL(&reloc->pending_queue, breloc, entry);
		return;
	}

	if (ftl_band_empty(band) && band->state == FTL_BAND_STATE_CLOSED) {
		ftl_band_set_state(breloc->band, FTL_BAND_STATE_FREE);

		if (breloc->defrag) {
			breloc->defrag = false;
			assert(reloc->num_defrag_bands > 0);
			reloc->num_defrag_bands--;
		}
	}
}

static void
ftl_process_reloc(struct ftl_band_reloc *breloc)
{
	ftl_reloc_process_moves(breloc);

	if (ftl_reloc_done(breloc)) {
		ftl_reloc_release(breloc);
	}
}

static int
ftl_band_reloc_init(struct ftl_reloc *reloc, struct ftl_band_reloc *breloc,
		    struct ftl_band *band)
{
	breloc->band = band;
	breloc->parent = reloc;

	breloc->reloc_map = spdk_bit_array_create(ftl_num_band_lbks(reloc->dev));
	if (!breloc->reloc_map) {
		SPDK_ERRLOG("Failed to initialize reloc map");
		return -1;
	}

	breloc->iter.chk_offset = calloc(ftl_dev_num_punits(band->dev),
					 sizeof(*breloc->iter.chk_offset));
	if (!breloc->iter.chk_offset) {
		SPDK_ERRLOG("Failed to initialize reloc iterator");
		return -1;
	}

	breloc->move_queue = spdk_ring_create(SPDK_RING_TYPE_MP_SC,
					      reloc->max_qdepth * 2,
					      SPDK_ENV_SOCKET_ID_ANY);
	if (!breloc->move_queue) {
		SPDK_ERRLOG("Failed to initialize reloc write queue");
		return -1;
	}

	breloc->moves = calloc(reloc->max_qdepth, sizeof(*breloc->moves));
	if (!breloc->moves) {
		return -1;
	}

	return 0;
}

static void
ftl_band_reloc_free(struct ftl_band_reloc *breloc)
{
	struct ftl_reloc *reloc;
	struct ftl_reloc_move *moves[FTL_RELOC_MAX_MOVES] = {};
	size_t i, num_moves;

	if (!breloc) {
		return;
	}

	assert(breloc->num_outstanding == 0);
	reloc = breloc->parent;

	/* Drain write queue if there is active band relocation during shutdown */
	if (breloc->active) {
		assert(reloc->halt);
		num_moves = spdk_ring_dequeue(breloc->move_queue, (void **)&moves, reloc->max_qdepth);
		for (i = 0; i < num_moves; ++i) {
			ftl_reloc_free_move(breloc, moves[i]);
		}
	}

	spdk_ring_free(breloc->move_queue);
	spdk_bit_array_free(&breloc->reloc_map);
	free(breloc->iter.chk_offset);
	free(breloc->moves);
}

static void
ftl_reloc_add_active_queue(struct ftl_band_reloc *breloc)
{
	struct ftl_reloc *reloc = breloc->parent;

	TAILQ_REMOVE(&reloc->pending_queue, breloc, entry);
	TAILQ_INSERT_HEAD(&reloc->active_queue, breloc, entry);
	ftl_reloc_prep(breloc);
}

struct ftl_reloc *
ftl_reloc_init(struct spdk_ftl_dev *dev)
{
#define POOL_NAME_LEN 128
	struct ftl_reloc *reloc;
	char pool_name[POOL_NAME_LEN];
	int rc;
	size_t i;

	reloc = calloc(1, sizeof(*reloc));
	if (!reloc) {
		return NULL;
	}

	reloc->dev = dev;
	reloc->halt = true;
	reloc->max_qdepth = dev->conf.max_reloc_qdepth;
	reloc->max_active = dev->conf.max_active_relocs;
	reloc->xfer_size = dev->xfer_size;
	reloc->num_defrag_bands = 0;

	if (reloc->max_qdepth > FTL_RELOC_MAX_MOVES) {
		goto error;
	}

	reloc->brelocs = calloc(ftl_dev_num_bands(dev), sizeof(*reloc->brelocs));
	if (!reloc->brelocs) {
		goto error;
	}

	for (i = 0; i < ftl_dev_num_bands(reloc->dev); ++i) {
		if (ftl_band_reloc_init(reloc, &reloc->brelocs[i], &dev->bands[i])) {
			goto error;
		}
	}

	rc = snprintf(pool_name, sizeof(pool_name), "%s-%s", dev->name, "reloc-io-pool");
	if (rc < 0 || rc >= POOL_NAME_LEN) {
		goto error;
	}

	TAILQ_INIT(&reloc->pending_queue);
	TAILQ_INIT(&reloc->active_queue);
	TAILQ_INIT(&reloc->prio_queue);

	return reloc;
error:
	ftl_reloc_free(reloc);
	return NULL;
}

void
ftl_reloc_free(struct ftl_reloc *reloc)
{
	size_t i;

	if (!reloc) {
		return;
	}

	for (i = 0; i < ftl_dev_num_bands(reloc->dev); ++i) {
		ftl_band_reloc_free(&reloc->brelocs[i]);
	}

	free(reloc->brelocs);
	free(reloc);
}

bool
ftl_reloc_is_halted(const struct ftl_reloc *reloc)
{
	return reloc->halt;
}

void
ftl_reloc_halt(struct ftl_reloc *reloc)
{
	reloc->halt = true;
}

void
ftl_reloc_resume(struct ftl_reloc *reloc)
{
	reloc->halt = false;
}

void
ftl_reloc(struct ftl_reloc *reloc)
{
	struct ftl_band_reloc *breloc, *tbreloc;

	if (ftl_reloc_is_halted(reloc)) {
		return;
	}

	/* Process first band from priority queue and return */
	breloc = TAILQ_FIRST(&reloc->prio_queue);
	if (breloc) {
		if (!breloc->active) {
			ftl_reloc_prep(breloc);
		}
		ftl_process_reloc(breloc);
		return;
	}

	TAILQ_FOREACH_SAFE(breloc, &reloc->pending_queue, entry, tbreloc) {
		if (reloc->num_active == reloc->max_active) {
			break;
		}

		/* TODO: Add handling relocation on open bands */
		if (breloc->band->state != FTL_BAND_STATE_CLOSED) {
			continue;
		}

		ftl_reloc_add_active_queue(breloc);
	}

	TAILQ_FOREACH_SAFE(breloc, &reloc->active_queue, entry, tbreloc) {
		ftl_process_reloc(breloc);
	}
}

void
ftl_reloc_add(struct ftl_reloc *reloc, struct ftl_band *band, size_t offset,
	      size_t num_lbks, int prio, bool is_defrag)
{
	struct ftl_band_reloc *breloc = &reloc->brelocs[band->id];
	size_t i, prev_lbks = breloc->num_lbks;

	/* No need to add anything if already at high prio - whole band should be relocated */
	if (!prio && band->high_prio) {
		return;
	}

	pthread_spin_lock(&band->lba_map.lock);
	if (band->lba_map.num_vld == 0) {
		pthread_spin_unlock(&band->lba_map.lock);

		/* If the band is closed and has no valid blocks, free it */
		if (band->state == FTL_BAND_STATE_CLOSED) {
			ftl_band_set_state(band, FTL_BAND_STATE_FREE);
		}

		return;
	}
	pthread_spin_unlock(&band->lba_map.lock);

	for (i = offset; i < offset + num_lbks; ++i) {
		if (spdk_bit_array_get(breloc->reloc_map, i)) {
			continue;
		}
		spdk_bit_array_set(breloc->reloc_map, i);
		breloc->num_lbks++;
	}

	if (!prio && prev_lbks == breloc->num_lbks) {
		return;
	}

	/* If the band is coming from the defrag process, mark it appropriately */
	if (is_defrag) {
		assert(offset == 0 && num_lbks == ftl_num_band_lbks(band->dev));
		reloc->num_defrag_bands++;
		breloc->defrag = true;
	}

	if (!prev_lbks && !prio && !breloc->active) {
		TAILQ_INSERT_HEAD(&reloc->pending_queue, breloc, entry);
	}

	if (prio) {
		struct ftl_band_reloc *iter_breloc;

		/* If priority band is already on pending or active queue, remove it from it */
		TAILQ_FOREACH(iter_breloc, &reloc->pending_queue, entry) {
			if (breloc == iter_breloc) {
				TAILQ_REMOVE(&reloc->pending_queue, breloc, entry);
				break;
			}
		}

		TAILQ_FOREACH(iter_breloc, &reloc->active_queue, entry) {
			if (breloc == iter_breloc) {
				TAILQ_REMOVE(&reloc->active_queue, breloc, entry);
				break;
			}
		}

		TAILQ_INSERT_TAIL(&reloc->prio_queue, breloc, entry);
		ftl_band_acquire_lba_map(breloc->band);
	}
}