Adding upstream version 16.2.11+ds.upstream/16.2.11+dsupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1350 insertions, 0 deletions

diff --git a/src/spdk/lib/ftl/ftl_restore.c b/src/spdk/lib/ftl/ftl_restore.c
new file mode 100644
index 000000000..6f626645d
--- /dev/null
+++ b/src/spdk/lib/ftl/ftl_restore.c
@@ -0,0 +1,1350 @@
+/*-
+ *   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/stdinc.h"
+#include "spdk/ftl.h"
+#include "spdk/util.h"
+#include "spdk/likely.h"
+#include "spdk/string.h"
+#include "spdk/crc32.h"
+
+#include "ftl_core.h"
+#include "ftl_band.h"
+#include "ftl_io.h"
+
+struct ftl_restore_band {
+	struct ftl_restore		*parent;
+	/* Associated band */
+	struct ftl_band			*band;
+	/* Status of retrieving this band's metadata */
+	enum ftl_md_status		md_status;
+	/* Padded queue link  */
+	STAILQ_ENTRY(ftl_restore_band)	stailq;
+};
+
+struct ftl_nv_cache_restore;
+
+/* Describes single phase to be restored from non-volatile cache */
+struct ftl_nv_cache_range {
+	struct ftl_nv_cache_restore	*parent;
+	/* Start offset */
+	uint64_t			start_addr;
+	/* Last block's address */
+	uint64_t			last_addr;
+	/*
+	 * Number of blocks (can be smaller than the difference between the last
+	 * and the starting block due to range overlap)
+	 */
+	uint64_t			num_blocks;
+	/* Number of blocks already recovered */
+	uint64_t			num_recovered;
+	/* Current address during recovery */
+	uint64_t			current_addr;
+	/* Phase of the range */
+	unsigned int			phase;
+	/* Indicates whether the data from this range needs to be recovered */
+	bool				recovery;
+};
+
+struct ftl_nv_cache_block {
+	struct ftl_nv_cache_restore	*parent;
+	/* Data buffer */
+	void				*buf;
+	/* Metadata buffer */
+	void				*md_buf;
+	/* Block offset within the cache */
+	uint64_t			offset;
+};
+
+struct ftl_nv_cache_restore {
+	struct ftl_nv_cache		*nv_cache;
+	/* IO channel to use */
+	struct spdk_io_channel		*ioch;
+	/*
+	 * Non-volatile cache ranges. The ranges can overlap, as we have no
+	 * control over the order of completions. The phase of the range is the
+	 * index within the table. The range with index 0 marks blocks that were
+	 * never written.
+	 */
+	struct ftl_nv_cache_range	range[FTL_NV_CACHE_PHASE_COUNT];
+#define FTL_NV_CACHE_RESTORE_DEPTH 128
+	/* Non-volatile cache buffers */
+	struct ftl_nv_cache_block	block[FTL_NV_CACHE_RESTORE_DEPTH];
+	/* Current address */
+	uint64_t			current_addr;
+	/* Number of outstanding requests */
+	size_t				num_outstanding;
+	/* Recovery/scan status */
+	int				status;
+	/* Current phase of the recovery */
+	unsigned int			phase;
+};
+
+struct ftl_restore {
+	struct spdk_ftl_dev		*dev;
+	/* Completion callback (called for each phase of the restoration) */
+	ftl_restore_fn			cb;
+	/* Completion callback context */
+	void				*cb_arg;
+	/* Number of inflight IOs */
+	unsigned int			num_ios;
+	/* Current band number (index in the below bands array) */
+	unsigned int			current;
+	/* Array of bands */
+	struct ftl_restore_band		*bands;
+	/* Queue of bands to be padded (due to unsafe shutdown) */
+	STAILQ_HEAD(, ftl_restore_band) pad_bands;
+	/* Status of the padding */
+	int				pad_status;
+	/* Metadata buffer */
+	void				*md_buf;
+	/* LBA map buffer */
+	void				*lba_map;
+	/* Indicates we're in the final phase of the restoration */
+	bool				final_phase;
+	/* Non-volatile cache recovery */
+	struct ftl_nv_cache_restore	nv_cache;
+};
+
+static int
+ftl_restore_tail_md(struct ftl_restore_band *rband);
+static void
+ftl_pad_zone_cb(struct ftl_io *io, void *arg, int status);
+static void
+ftl_restore_pad_band(struct ftl_restore_band *rband);
+
+static void
+ftl_restore_free(struct ftl_restore *restore)
+{
+	unsigned int i;
+
+	if (!restore) {
+		return;
+	}
+
+	for (i = 0; i < FTL_NV_CACHE_RESTORE_DEPTH; ++i) {
+		spdk_dma_free(restore->nv_cache.block[i].buf);
+	}
+
+	spdk_dma_free(restore->md_buf);
+	free(restore->bands);
+	free(restore);
+}
+
+static struct ftl_restore *
+ftl_restore_init(struct spdk_ftl_dev *dev, ftl_restore_fn cb, void *cb_arg)
+{
+	struct ftl_restore *restore;
+	struct ftl_restore_band *rband;
+	size_t i;
+
+	restore = calloc(1, sizeof(*restore));
+	if (!restore) {
+		goto error;
+	}
+
+	restore->dev = dev;
+	restore->cb = cb;
+	restore->cb_arg = cb_arg;
+	restore->final_phase = false;
+
+	restore->bands = calloc(ftl_get_num_bands(dev), sizeof(*restore->bands));
+	if (!restore->bands) {
+		goto error;
+	}
+
+	STAILQ_INIT(&restore->pad_bands);
+
+	for (i = 0; i < ftl_get_num_bands(dev); ++i) {
+		rband = &restore->bands[i];
+		rband->band = &dev->bands[i];
+		rband->parent = restore;
+		rband->md_status = FTL_MD_NO_MD;
+	}
+
+	/* Allocate buffer capable of holding head mds of all bands */
+	restore->md_buf = spdk_dma_zmalloc(ftl_get_num_bands(dev) * ftl_head_md_num_blocks(dev) *
+					   FTL_BLOCK_SIZE, 0, NULL);
+	if (!restore->md_buf) {
+		goto error;
+	}
+
+	return restore;
+error:
+	ftl_restore_free(restore);
+	return NULL;
+}
+
+static void
+ftl_restore_complete(struct ftl_restore *restore, int status)
+{
+	struct ftl_restore *ctx = status ? NULL : restore;
+	bool final_phase = restore->final_phase;
+
+	restore->cb(ctx, status, restore->cb_arg);
+	if (status || final_phase) {
+		ftl_restore_free(restore);
+	}
+}
+
+static int
+ftl_band_cmp(const void *lband, const void *rband)
+{
+	uint64_t lseq = ((struct ftl_restore_band *)lband)->band->seq;
+	uint64_t rseq = ((struct ftl_restore_band *)rband)->band->seq;
+
+	if (lseq < rseq) {
+		return -1;
+	} else {
+		return 1;
+	}
+}
+
+static int
+ftl_restore_check_seq(const struct ftl_restore *restore)
+{
+	const struct spdk_ftl_dev *dev = restore->dev;
+	const struct ftl_restore_band *rband;
+	const struct ftl_band *next_band;
+	size_t i;
+
+	for (i = 0; i < ftl_get_num_bands(dev); ++i) {
+		rband = &restore->bands[i];
+		if (rband->md_status != FTL_MD_SUCCESS) {
+			continue;
+		}
+
+		next_band = LIST_NEXT(rband->band, list_entry);
+		if (next_band && rband->band->seq == next_band->seq) {
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+static bool
+ftl_restore_head_valid(struct spdk_ftl_dev *dev, struct ftl_restore *restore, size_t *num_valid)
+{
+	struct ftl_restore_band *rband;
+	size_t i;
+
+	for (i = 0; i < ftl_get_num_bands(dev); ++i) {
+		rband = &restore->bands[i];
+
+		if (rband->md_status != FTL_MD_SUCCESS &&
+		    rband->md_status != FTL_MD_NO_MD &&
+		    rband->md_status != FTL_MD_IO_FAILURE) {
+			SPDK_ERRLOG("Inconsistent head metadata found on band %u\n",
+				    rband->band->id);
+			return false;
+		}
+
+		if (rband->md_status == FTL_MD_SUCCESS) {
+			(*num_valid)++;
+		}
+	}
+
+	return true;
+}
+
+static void
+ftl_restore_head_complete(struct ftl_restore *restore)
+{
+	struct spdk_ftl_dev *dev = restore->dev;
+	size_t num_valid = 0;
+	int status = -EIO;
+
+	if (!ftl_restore_head_valid(dev, restore, &num_valid)) {
+		goto out;
+	}
+
+	if (num_valid == 0) {
+		SPDK_ERRLOG("Couldn't find any valid bands\n");
+		goto out;
+	}
+
+	/* Sort bands in sequence number ascending order */
+	qsort(restore->bands, ftl_get_num_bands(dev), sizeof(struct ftl_restore_band),
+	      ftl_band_cmp);
+
+	if (ftl_restore_check_seq(restore)) {
+		SPDK_ERRLOG("Band sequence consistency failed\n");
+		goto out;
+	}
+
+	dev->num_lbas = dev->global_md.num_lbas;
+	status = 0;
+out:
+	ftl_restore_complete(restore, status);
+}
+
+static void
+ftl_restore_head_cb(struct ftl_io *io, void *ctx, int status)
+{
+	struct ftl_restore_band *rband = ctx;
+	struct ftl_restore *restore = rband->parent;
+	unsigned int num_ios;
+
+	rband->md_status = status;
+	num_ios = __atomic_fetch_sub(&restore->num_ios, 1, __ATOMIC_SEQ_CST);
+	assert(num_ios > 0);
+
+	if (num_ios == 1) {
+		ftl_restore_head_complete(restore);
+	}
+}
+
+static void
+ftl_restore_head_md(void *ctx)
+{
+	struct ftl_restore *restore = ctx;
+	struct spdk_ftl_dev *dev = restore->dev;
+	struct ftl_restore_band *rband;
+	struct ftl_lba_map *lba_map;
+	unsigned int num_failed = 0, num_ios;
+	size_t i;
+
+	restore->num_ios = ftl_get_num_bands(dev);
+
+	for (i = 0; i < ftl_get_num_bands(dev); ++i) {
+		rband = &restore->bands[i];
+		lba_map = &rband->band->lba_map;
+
+		lba_map->dma_buf = restore->md_buf + i * ftl_head_md_num_blocks(dev) * FTL_BLOCK_SIZE;
+
+		if (ftl_band_read_head_md(rband->band, ftl_restore_head_cb, rband)) {
+			if (spdk_likely(rband->band->num_zones)) {
+				SPDK_ERRLOG("Failed to read metadata on band %zu\n", i);
+
+				rband->md_status = FTL_MD_INVALID_CRC;
+
+				/* If the first IO fails, don't bother sending anything else */
+				if (i == 0) {
+					ftl_restore_complete(restore, -EIO);
+				}
+			}
+
+			num_failed++;
+		}
+	}
+
+	if (spdk_unlikely(num_failed > 0)) {
+		num_ios = __atomic_fetch_sub(&restore->num_ios, num_failed, __ATOMIC_SEQ_CST);
+		if (num_ios == num_failed) {
+			ftl_restore_complete(restore, -EIO);
+		}
+	}
+}
+
+int
+ftl_restore_md(struct spdk_ftl_dev *dev, ftl_restore_fn cb, void *cb_arg)
+{
+	struct ftl_restore *restore;
+
+	restore = ftl_restore_init(dev, cb, cb_arg);
+	if (!restore) {
+		return -ENOMEM;
+	}
+
+	spdk_thread_send_msg(ftl_get_core_thread(dev), ftl_restore_head_md, restore);
+
+	return 0;
+}
+
+static int
+ftl_restore_l2p(struct ftl_band *band)
+{
+	struct spdk_ftl_dev *dev = band->dev;
+	struct ftl_addr addr;
+	uint64_t lba;
+	size_t i;
+
+	for (i = 0; i < ftl_get_num_blocks_in_band(band->dev); ++i) {
+		if (!spdk_bit_array_get(band->lba_map.vld, i)) {
+			continue;
+		}
+
+		lba = band->lba_map.map[i];
+		if (lba >= dev->num_lbas) {
+			return -1;
+		}
+
+		addr = ftl_l2p_get(dev, lba);
+		if (!ftl_addr_invalid(addr)) {
+			ftl_invalidate_addr(dev, addr);
+		}
+
+		addr = ftl_band_addr_from_block_offset(band, i);
+
+		ftl_band_set_addr(band, lba, addr);
+		ftl_l2p_set(dev, lba, addr);
+	}
+
+	return 0;
+}
+
+static struct ftl_restore_band *
+ftl_restore_next_band(struct ftl_restore *restore)
+{
+	struct ftl_restore_band *rband;
+
+	for (; restore->current < ftl_get_num_bands(restore->dev); ++restore->current) {
+		rband = &restore->bands[restore->current];
+
+		if (spdk_likely(rband->band->num_zones) &&
+		    rband->md_status == FTL_MD_SUCCESS) {
+			restore->current++;
+			return rband;
+		}
+	}
+
+	return NULL;
+}
+
+static void
+ftl_nv_cache_restore_complete(struct ftl_nv_cache_restore *restore, int status)
+{
+	struct ftl_restore *ftl_restore = SPDK_CONTAINEROF(restore, struct ftl_restore, nv_cache);
+
+	restore->status = restore->status ? : status;
+	if (restore->num_outstanding == 0) {
+		ftl_restore_complete(ftl_restore, restore->status);
+	}
+}
+
+static void ftl_nv_cache_block_read_cb(struct spdk_bdev_io *bdev_io, bool success, void *cb_arg);
+
+static void
+ftl_nv_cache_restore_done(struct ftl_nv_cache_restore *restore, uint64_t current_addr)
+{
+	struct ftl_nv_cache *nv_cache = restore->nv_cache;
+
+	pthread_spin_lock(&nv_cache->lock);
+	nv_cache->current_addr = current_addr;
+	nv_cache->ready = true;
+	pthread_spin_unlock(&nv_cache->lock);
+
+	SPDK_DEBUGLOG(SPDK_LOG_FTL_INIT, "Enabling non-volatile cache (phase: %u, addr: %"
+		      PRIu64")\n", nv_cache->phase, current_addr);
+
+	ftl_nv_cache_restore_complete(restore, 0);
+}
+
+static void
+ftl_nv_cache_write_header_cb(struct spdk_bdev_io *bdev_io, bool success, void *cb_arg)
+{
+	struct ftl_nv_cache_restore *restore = cb_arg;
+
+	spdk_bdev_free_io(bdev_io);
+	if (spdk_unlikely(!success)) {
+		SPDK_ERRLOG("Unable to write the non-volatile cache metadata header\n");
+		ftl_nv_cache_restore_complete(restore, -EIO);
+		return;
+	}
+
+	ftl_nv_cache_restore_done(restore, FTL_NV_CACHE_DATA_OFFSET);
+}
+
+static void
+ftl_nv_cache_scrub_cb(struct spdk_bdev_io *bdev_io, bool success, void *cb_arg)
+{
+	struct ftl_nv_cache_restore *restore = cb_arg;
+	struct ftl_nv_cache *nv_cache = restore->nv_cache;
+	int rc;
+
+	spdk_bdev_free_io(bdev_io);
+	if (spdk_unlikely(!success)) {
+		SPDK_ERRLOG("Scrubbing non-volatile cache failed\n");
+		ftl_nv_cache_restore_complete(restore, -EIO);
+		return;
+	}
+
+	nv_cache->phase = 1;
+	rc = ftl_nv_cache_write_header(nv_cache, false, ftl_nv_cache_write_header_cb, restore);
+	if (spdk_unlikely(rc != 0)) {
+		SPDK_ERRLOG("Unable to write the non-volatile cache metadata header: %s\n",
+			    spdk_strerror(-rc));
+		ftl_nv_cache_restore_complete(restore, -EIO);
+	}
+}
+
+static void
+ftl_nv_cache_scrub_header_cb(struct spdk_bdev_io *bdev_io, bool success, void *cb_arg)
+{
+	struct ftl_nv_cache_restore *restore = cb_arg;
+	struct ftl_nv_cache *nv_cache = restore->nv_cache;
+	int rc;
+
+	spdk_bdev_free_io(bdev_io);
+	if (spdk_unlikely(!success)) {
+		SPDK_ERRLOG("Unable to write non-volatile cache metadata header\n");
+		ftl_nv_cache_restore_complete(restore, -EIO);
+		return;
+	}
+
+	rc = ftl_nv_cache_scrub(nv_cache, ftl_nv_cache_scrub_cb, restore);
+	if (spdk_unlikely(rc != 0)) {
+		SPDK_ERRLOG("Unable to scrub the non-volatile cache: %s\n", spdk_strerror(-rc));
+		ftl_nv_cache_restore_complete(restore, rc);
+	}
+}
+
+static void
+ftl_nv_cache_band_flush_cb(void *ctx, int status)
+{
+	struct ftl_nv_cache_restore *restore = ctx;
+	struct ftl_nv_cache *nv_cache = restore->nv_cache;
+	int rc;
+
+	if (spdk_unlikely(status != 0)) {
+		SPDK_ERRLOG("Flushing active bands failed: %s\n", spdk_strerror(-status));
+		ftl_nv_cache_restore_complete(restore, status);
+		return;
+	}
+
+	/*
+	 * Use phase 0 to indicate that the cache is being scrubbed. If the power is lost during
+	 * this process, we'll know it needs to be resumed.
+	 */
+	nv_cache->phase = 0;
+	rc = ftl_nv_cache_write_header(nv_cache, false, ftl_nv_cache_scrub_header_cb, restore);
+	if (spdk_unlikely(rc != 0)) {
+		SPDK_ERRLOG("Unable to write non-volatile cache metadata header: %s\n",
+			    spdk_strerror(-rc));
+		ftl_nv_cache_restore_complete(restore, rc);
+	}
+}
+
+static void
+ftl_nv_cache_wbuf_flush_cb(void *ctx, int status)
+{
+	struct ftl_nv_cache_restore *restore = ctx;
+	struct ftl_nv_cache *nv_cache = restore->nv_cache;
+	struct spdk_ftl_dev *dev = SPDK_CONTAINEROF(nv_cache, struct spdk_ftl_dev, nv_cache);
+	int rc;
+
+	if (spdk_unlikely(status != 0)) {
+		SPDK_ERRLOG("Flushing the write buffer failed: %s\n", spdk_strerror(-status));
+		ftl_nv_cache_restore_complete(restore, status);
+		return;
+	}
+
+	rc = ftl_flush_active_bands(dev, ftl_nv_cache_band_flush_cb, restore);
+	if (spdk_unlikely(rc != 0)) {
+		SPDK_ERRLOG("Unable to flush active bands: %s\n", spdk_strerror(-rc));
+		ftl_nv_cache_restore_complete(restore, rc);
+	}
+}
+
+static void
+ftl_nv_cache_recovery_done(struct ftl_nv_cache_restore *restore)
+{
+	struct ftl_nv_cache *nv_cache = restore->nv_cache;
+	struct ftl_nv_cache_range *range_prev, *range_current;
+	struct spdk_ftl_dev *dev = SPDK_CONTAINEROF(nv_cache, struct spdk_ftl_dev, nv_cache);
+	struct spdk_bdev *bdev;
+	uint64_t current_addr;
+	int rc;
+
+	range_prev = &restore->range[ftl_nv_cache_prev_phase(nv_cache->phase)];
+	range_current = &restore->range[nv_cache->phase];
+	bdev = spdk_bdev_desc_get_bdev(nv_cache->bdev_desc);
+
+	/*
+	 * If there are more than two ranges or the ranges overlap, scrub the non-volatile cache to
+	 * make sure that any subsequent power loss will find the cache in usable state
+	 */
+	if ((range_prev->num_blocks + range_current->num_blocks < nv_cache->num_data_blocks) ||
+	    (range_prev->start_addr < range_current->last_addr &&
+	     range_current->start_addr < range_prev->last_addr)) {
+		SPDK_DEBUGLOG(SPDK_LOG_FTL_INIT, "Non-volatile cache inconsistency detected\n");
+
+		rc = ftl_flush_wbuf(dev, ftl_nv_cache_wbuf_flush_cb, restore);
+		if (spdk_unlikely(rc != 0)) {
+			SPDK_ERRLOG("Unable to flush the write buffer: %s\n", spdk_strerror(-rc));
+			ftl_nv_cache_restore_complete(restore, rc);
+		}
+
+		return;
+	}
+
+	/* The latest phase is the one written in the header (set in nvc_cache->phase) */
+	current_addr = range_current->last_addr + 1;
+
+	/*
+	 * The first range might be empty (only the header was written) or the range might
+	 * end at the last available address, in which case set current address to the
+	 * beginning of the device.
+	 */
+	if (range_current->num_blocks == 0 || current_addr >= spdk_bdev_get_num_blocks(bdev)) {
+		current_addr = FTL_NV_CACHE_DATA_OFFSET;
+	}
+
+	ftl_nv_cache_restore_done(restore, current_addr);
+}
+
+static void
+ftl_nv_cache_recover_block(struct ftl_nv_cache_block *block)
+{
+	struct ftl_nv_cache_restore *restore = block->parent;
+	struct ftl_nv_cache *nv_cache = restore->nv_cache;
+	struct ftl_nv_cache_range *range = &restore->range[restore->phase];
+	int rc;
+
+	assert(range->current_addr <= range->last_addr);
+
+	restore->num_outstanding++;
+	block->offset = range->current_addr++;
+	rc = spdk_bdev_read_blocks_with_md(nv_cache->bdev_desc, restore->ioch,
+					   block->buf, block->md_buf,
+					   block->offset, 1, ftl_nv_cache_block_read_cb,
+					   block);
+	if (spdk_unlikely(rc != 0)) {
+		SPDK_ERRLOG("Non-volatile cache restoration failed on block %"PRIu64" (%s)\n",
+			    block->offset, spdk_strerror(-rc));
+		restore->num_outstanding--;
+		ftl_nv_cache_restore_complete(restore, rc);
+	}
+}
+
+static void
+ftl_nv_cache_recover_range(struct ftl_nv_cache_restore *restore)
+{
+	struct ftl_nv_cache_range *range;
+	unsigned int phase = restore->phase;
+
+	do {
+		/* Find first range with non-zero number of blocks that is marked for recovery */
+		range = &restore->range[phase];
+		if (range->recovery && range->num_recovered < range->num_blocks) {
+			break;
+		}
+
+		phase = ftl_nv_cache_next_phase(phase);
+	} while (phase != restore->phase);
+
+	/* There are no ranges to be recovered, we're done */
+	if (range->num_recovered == range->num_blocks || !range->recovery) {
+		SPDK_DEBUGLOG(SPDK_LOG_FTL_INIT, "Non-volatile cache recovery done\n");
+		ftl_nv_cache_recovery_done(restore);
+		return;
+	}
+
+	range->current_addr = range->start_addr;
+	restore->phase = phase;
+
+	SPDK_DEBUGLOG(SPDK_LOG_FTL_INIT, "Recovering range %u %"PRIu64"-%"PRIu64" (%"PRIu64")\n",
+		      phase, range->start_addr, range->last_addr, range->num_blocks);
+
+	ftl_nv_cache_recover_block(&restore->block[0]);
+}
+
+static void
+ftl_nv_cache_write_cb(struct ftl_io *io, void *cb_arg, int status)
+{
+	struct ftl_nv_cache_block *block = cb_arg;
+	struct ftl_nv_cache_restore *restore = block->parent;
+	struct ftl_nv_cache_range *range = &restore->range[restore->phase];
+
+	restore->num_outstanding--;
+	if (status != 0) {
+		SPDK_ERRLOG("Non-volatile cache restoration failed on block %"PRIu64" (%s)\n",
+			    block->offset, spdk_strerror(-status));
+		ftl_nv_cache_restore_complete(restore, -ENOMEM);
+		return;
+	}
+
+	range->num_recovered++;
+	if (range->current_addr <= range->last_addr) {
+		ftl_nv_cache_recover_block(block);
+	} else if (restore->num_outstanding == 0) {
+		assert(range->num_recovered == range->num_blocks);
+		ftl_nv_cache_recover_range(restore);
+	}
+}
+
+static struct ftl_io *
+ftl_nv_cache_alloc_io(struct ftl_nv_cache_block *block, uint64_t lba)
+{
+	struct ftl_restore *restore = SPDK_CONTAINEROF(block->parent, struct ftl_restore, nv_cache);
+	struct ftl_io_init_opts opts = {
+		.dev		= restore->dev,
+		.io		= NULL,
+		.flags		= FTL_IO_BYPASS_CACHE,
+		.type		= FTL_IO_WRITE,
+		.num_blocks	= 1,
+		.cb_fn		= ftl_nv_cache_write_cb,
+		.cb_ctx		= block,
+		.iovs		= {
+			{
+				.iov_base = block->buf,
+				.iov_len = FTL_BLOCK_SIZE,
+			}
+		},
+		.iovcnt		= 1,
+	};
+	struct ftl_io *io;
+
+	io = ftl_io_init_internal(&opts);
+	if (spdk_unlikely(!io)) {
+		return NULL;
+	}
+
+	io->lba.single = lba;
+	return io;
+}
+
+static void
+ftl_nv_cache_block_read_cb(struct spdk_bdev_io *bdev_io, bool success, void *cb_arg)
+{
+	struct ftl_nv_cache_block *block = cb_arg;
+	struct ftl_nv_cache_restore *restore = block->parent;
+	struct ftl_nv_cache_range *range = &restore->range[restore->phase];
+	struct ftl_io *io;
+	unsigned int phase;
+	uint64_t lba;
+
+	spdk_bdev_free_io(bdev_io);
+	restore->num_outstanding--;
+
+	if (!success) {
+		SPDK_ERRLOG("Non-volatile cache restoration failed on block %"PRIu64"\n",
+			    block->offset);
+		ftl_nv_cache_restore_complete(restore, -EIO);
+		return;
+	}
+
+	ftl_nv_cache_unpack_lba(*(uint64_t *)block->md_buf, &lba, &phase);
+	if (spdk_unlikely(phase != restore->phase)) {
+		if (range->current_addr < range->last_addr) {
+			ftl_nv_cache_recover_block(block);
+		} else if (restore->num_outstanding == 0) {
+			ftl_nv_cache_recover_range(restore);
+		}
+
+		return;
+	}
+
+	io = ftl_nv_cache_alloc_io(block, lba);
+	if (spdk_unlikely(!io)) {
+		SPDK_ERRLOG("Failed to allocate ftl_io during non-volatile cache recovery\n");
+		ftl_nv_cache_restore_complete(restore, -ENOMEM);
+		return;
+	}
+
+	restore->num_outstanding++;
+	ftl_io_write(io);
+}
+
+/*
+ * Since we have no control over the order in which the requests complete in regards to their
+ * submission, the cache can be in either of the following states:
+ *  - [1 1 1 1 1 1 1 1 1 1]: simplest case, whole cache contains single phase (although it should be
+ *			     very rare),
+ *  - [1 1 1 1 3 3 3 3 3 3]: two phases, changing somewhere in the middle with no overlap. This is
+ *			     the state left by clean shutdown,
+ *  - [1 1 1 1 3 1 3 3 3 3]: similar to the above, but this time the two ranges overlap. This
+ *			     happens when completions are reordered during unsafe shutdown,
+ *  - [2 1 2 1 1 1 1 3 1 3]: three different phases, each one of which can overlap with
+ *			     previous/next one. The data from the oldest phase doesn't need to be
+ *			     recovered, as it was already being written to, which means it's
+ *			     already on the main storage.
+ */
+static void
+ftl_nv_cache_scan_done(struct ftl_nv_cache_restore *restore)
+{
+	struct ftl_nv_cache *nv_cache = restore->nv_cache;
+#if defined(DEBUG)
+	struct ftl_nv_cache_range *range;
+	uint64_t i, num_blocks = 0;
+
+	for (i = 0; i < FTL_NV_CACHE_PHASE_COUNT; ++i) {
+		range = &restore->range[i];
+		SPDK_DEBUGLOG(SPDK_LOG_FTL_INIT, "Range %"PRIu64": %"PRIu64"-%"PRIu64" (%" PRIu64
+			      ")\n", i, range->start_addr, range->last_addr, range->num_blocks);
+		num_blocks += range->num_blocks;
+	}
+	assert(num_blocks == nv_cache->num_data_blocks);
+#endif
+	restore->phase = ftl_nv_cache_prev_phase(nv_cache->phase);
+
+	/*
+	 * Only the latest two phases need to be recovered. The third one, even if present,
+	 * already has to be stored on the main storage, as it's already started to be
+	 * overwritten (only present here because of reordering of requests' completions).
+	 */
+	restore->range[nv_cache->phase].recovery = true;
+	restore->range[restore->phase].recovery = true;
+
+	ftl_nv_cache_recover_range(restore);
+}
+
+static int ftl_nv_cache_scan_block(struct ftl_nv_cache_block *block);
+
+static void
+ftl_nv_cache_scan_cb(struct spdk_bdev_io *bdev_io, bool success, void *cb_arg)
+{
+	struct ftl_nv_cache_block *block = cb_arg;
+	struct ftl_nv_cache_restore *restore = block->parent;
+	struct ftl_nv_cache_range *range;
+	struct spdk_bdev *bdev;
+	unsigned int phase;
+	uint64_t lba;
+
+	restore->num_outstanding--;
+	bdev = spdk_bdev_desc_get_bdev(restore->nv_cache->bdev_desc);
+	spdk_bdev_free_io(bdev_io);
+
+	if (!success) {
+		SPDK_ERRLOG("Non-volatile cache scan failed on block %"PRIu64"\n",
+			    block->offset);
+		ftl_nv_cache_restore_complete(restore, -EIO);
+		return;
+	}
+
+	/* If we've already hit an error, don't bother with scanning anything else */
+	if (spdk_unlikely(restore->status != 0)) {
+		ftl_nv_cache_restore_complete(restore, restore->status);
+		return;
+	}
+
+	ftl_nv_cache_unpack_lba(*(uint64_t *)block->md_buf, &lba, &phase);
+	range = &restore->range[phase];
+	range->num_blocks++;
+
+	if (range->start_addr == FTL_LBA_INVALID || range->start_addr > block->offset) {
+		range->start_addr = block->offset;
+	}
+
+	if (range->last_addr == FTL_LBA_INVALID || range->last_addr < block->offset) {
+		range->last_addr = block->offset;
+	}
+
+	/* All the blocks were read, once they're all completed and we're finished */
+	if (restore->current_addr == spdk_bdev_get_num_blocks(bdev)) {
+		if (restore->num_outstanding == 0) {
+			ftl_nv_cache_scan_done(restore);
+		}
+
+		return;
+	}
+
+	ftl_nv_cache_scan_block(block);
+}
+
+static int
+ftl_nv_cache_scan_block(struct ftl_nv_cache_block *block)
+{
+	struct ftl_nv_cache_restore *restore = block->parent;
+	struct ftl_nv_cache *nv_cache = restore->nv_cache;
+	int rc;
+
+	restore->num_outstanding++;
+	block->offset = restore->current_addr++;
+	rc = spdk_bdev_read_blocks_with_md(nv_cache->bdev_desc, restore->ioch,
+					   block->buf, block->md_buf,
+					   block->offset, 1, ftl_nv_cache_scan_cb,
+					   block);
+	if (spdk_unlikely(rc != 0)) {
+		SPDK_ERRLOG("Non-volatile cache scan failed on block %"PRIu64" (%s)\n",
+			    block->offset, spdk_strerror(-rc));
+		restore->num_outstanding--;
+		ftl_nv_cache_restore_complete(restore, rc);
+		return rc;
+	}
+
+	return 0;
+}
+
+static void
+ftl_nv_cache_clean_header_cb(struct spdk_bdev_io *bdev_io, bool success, void *cb_arg)
+{
+	struct ftl_nv_cache_restore *restore = cb_arg;
+
+	spdk_bdev_free_io(bdev_io);
+	if (spdk_unlikely(!success)) {
+		SPDK_ERRLOG("Unable to write the non-volatile cache metadata header\n");
+		ftl_nv_cache_restore_complete(restore, -EIO);
+		return;
+	}
+
+	ftl_nv_cache_restore_done(restore, restore->current_addr);
+}
+
+static bool
+ftl_nv_cache_header_valid(struct spdk_ftl_dev *dev, const struct ftl_nv_cache_header *hdr)
+{
+	struct spdk_bdev *bdev = spdk_bdev_desc_get_bdev(dev->nv_cache.bdev_desc);
+	uint32_t checksum;
+
+	checksum = spdk_crc32c_update(hdr, offsetof(struct ftl_nv_cache_header, checksum), 0);
+	if (checksum != hdr->checksum) {
+		SPDK_ERRLOG("Invalid header checksum (found: %"PRIu32", expected: %"PRIu32")\n",
+			    checksum, hdr->checksum);
+		return false;
+	}
+
+	if (hdr->version != FTL_NV_CACHE_HEADER_VERSION) {
+		SPDK_ERRLOG("Invalid header version (found: %"PRIu32", expected: %"PRIu32")\n",
+			    hdr->version, FTL_NV_CACHE_HEADER_VERSION);
+		return false;
+	}
+
+	if (hdr->size != spdk_bdev_get_num_blocks(bdev)) {
+		SPDK_ERRLOG("Unexpected size of the non-volatile cache bdev (%"PRIu64", expected: %"
+			    PRIu64")\n", hdr->size, spdk_bdev_get_num_blocks(bdev));
+		return false;
+	}
+
+	if (spdk_uuid_compare(&hdr->uuid, &dev->uuid)) {
+		SPDK_ERRLOG("Invalid device UUID\n");
+		return false;
+	}
+
+	if (!ftl_nv_cache_phase_is_valid(hdr->phase) && hdr->phase != 0) {
+		return false;
+	}
+
+	if ((hdr->current_addr >= spdk_bdev_get_num_blocks(bdev) ||
+	     hdr->current_addr  < FTL_NV_CACHE_DATA_OFFSET) &&
+	    (hdr->current_addr != FTL_LBA_INVALID)) {
+		SPDK_ERRLOG("Unexpected value of non-volatile cache's current address: %"PRIu64"\n",
+			    hdr->current_addr);
+		return false;
+	}
+
+	return true;
+}
+
+static void
+ftl_nv_cache_read_header_cb(struct spdk_bdev_io *bdev_io, bool success, void *cb_arg)
+{
+	struct ftl_restore *restore = cb_arg;
+	struct spdk_ftl_dev *dev = restore->dev;
+	struct ftl_nv_cache *nv_cache = &dev->nv_cache;
+	struct ftl_nv_cache_header *hdr;
+	struct iovec *iov = NULL;
+	int iov_cnt = 0, i, rc;
+
+	if (!success) {
+		SPDK_ERRLOG("Unable to read non-volatile cache metadata header\n");
+		ftl_restore_complete(restore, -ENOTRECOVERABLE);
+		goto out;
+	}
+
+	spdk_bdev_io_get_iovec(bdev_io, &iov, &iov_cnt);
+	assert(iov != NULL);
+	hdr = iov[0].iov_base;
+
+	if (!ftl_nv_cache_header_valid(dev, hdr)) {
+		ftl_restore_complete(restore, -ENOTRECOVERABLE);
+		goto out;
+	}
+
+	/* Remember the latest phase */
+	nv_cache->phase = hdr->phase;
+
+	/* If the phase equals zero, we lost power during recovery. We need to finish it up
+	 * by scrubbing the device once again.
+	 */
+	if (hdr->phase == 0) {
+		SPDK_DEBUGLOG(SPDK_LOG_FTL_INIT, "Detected phase 0, restarting scrub\n");
+		rc = ftl_nv_cache_scrub(nv_cache, ftl_nv_cache_scrub_cb, restore);
+		if (spdk_unlikely(rc != 0)) {
+			SPDK_ERRLOG("Unable to scrub the non-volatile cache: %s\n",
+				    spdk_strerror(-rc));
+			ftl_restore_complete(restore, -ENOTRECOVERABLE);
+		}
+
+		goto out;
+	}
+
+	/* Valid current_addr means that the shutdown was clean, so we just need to overwrite the
+	 * header to make sure that any power loss occurring before the cache is wrapped won't be
+	 * mistaken for a clean shutdown.
+	 */
+	if (hdr->current_addr != FTL_LBA_INVALID) {
+		restore->nv_cache.current_addr = hdr->current_addr;
+
+		rc = ftl_nv_cache_write_header(nv_cache, false, ftl_nv_cache_clean_header_cb,
+					       &restore->nv_cache);
+		if (spdk_unlikely(rc != 0)) {
+			SPDK_ERRLOG("Failed to overwrite the non-volatile cache header: %s\n",
+				    spdk_strerror(-rc));
+			ftl_restore_complete(restore, -ENOTRECOVERABLE);
+		}
+
+		goto out;
+	}
+
+	/* Otherwise the shutdown was unexpected, so we need to recover the data from the cache */
+	restore->nv_cache.current_addr = FTL_NV_CACHE_DATA_OFFSET;
+
+	for (i = 0; i < FTL_NV_CACHE_RESTORE_DEPTH; ++i) {
+		if (ftl_nv_cache_scan_block(&restore->nv_cache.block[i])) {
+			break;
+		}
+	}
+out:
+	spdk_bdev_free_io(bdev_io);
+}
+
+void
+ftl_restore_nv_cache(struct ftl_restore *restore, ftl_restore_fn cb, void *cb_arg)
+{
+	struct spdk_ftl_dev *dev = restore->dev;
+	struct spdk_bdev *bdev;
+	struct ftl_nv_cache *nv_cache = &dev->nv_cache;
+	struct ftl_io_channel *ioch;
+	struct ftl_nv_cache_restore *nvc_restore = &restore->nv_cache;
+	struct ftl_nv_cache_block *block;
+	size_t alignment;
+	int rc, i;
+
+	ioch = ftl_io_channel_get_ctx(ftl_get_io_channel(dev));
+	bdev = spdk_bdev_desc_get_bdev(nv_cache->bdev_desc);
+	alignment = spdk_max(spdk_bdev_get_buf_align(bdev), sizeof(uint64_t));
+
+	nvc_restore->nv_cache = nv_cache;
+	nvc_restore->ioch = ioch->cache_ioch;
+
+	restore->final_phase = true;
+	restore->cb = cb;
+	restore->cb_arg = cb_arg;
+
+	for (i = 0; i < FTL_NV_CACHE_RESTORE_DEPTH; ++i) {
+		block = &nvc_restore->block[i];
+		block->parent = nvc_restore;
+		block->buf = spdk_dma_zmalloc(spdk_bdev_get_block_size(bdev) +
+					      spdk_bdev_get_md_size(bdev),
+					      alignment, NULL);
+		if (!block->buf) {
+			/* The memory will be freed in ftl_restore_free */
+			SPDK_ERRLOG("Unable to allocate memory\n");
+			ftl_restore_complete(restore, -ENOMEM);
+			return;
+		}
+
+		block->md_buf = (char *)block->buf + spdk_bdev_get_block_size(bdev);
+	}
+
+	for (i = 0; i < FTL_NV_CACHE_PHASE_COUNT; ++i) {
+		nvc_restore->range[i].parent = nvc_restore;
+		nvc_restore->range[i].start_addr = FTL_LBA_INVALID;
+		nvc_restore->range[i].last_addr = FTL_LBA_INVALID;
+		nvc_restore->range[i].num_blocks = 0;
+		nvc_restore->range[i].recovery = false;
+		nvc_restore->range[i].phase = i;
+	}
+
+	rc = spdk_bdev_read_blocks(nv_cache->bdev_desc, ioch->cache_ioch, nv_cache->dma_buf,
+				   0, FTL_NV_CACHE_DATA_OFFSET, ftl_nv_cache_read_header_cb, restore);
+	if (spdk_unlikely(rc != 0)) {
+		SPDK_ERRLOG("Failed to read non-volatile cache metadata header: %s\n",
+			    spdk_strerror(-rc));
+		ftl_restore_complete(restore, rc);
+	}
+}
+
+static bool
+ftl_pad_zone_pad_finish(struct ftl_restore_band *rband, bool direct_access)
+{
+	struct ftl_restore *restore = rband->parent;
+	struct ftl_restore_band *next_band;
+	size_t i, num_pad_zones = 0;
+
+	if (spdk_unlikely(restore->pad_status && !restore->num_ios)) {
+		if (direct_access) {
+			/* In case of any errors found we want to clear direct access. */
+			/* Direct access bands have their own allocated md, which would be lost */
+			/* on restore complete otherwise. */
+			rband->band->state = FTL_BAND_STATE_CLOSED;
+			ftl_band_set_direct_access(rband->band, false);
+		}
+		ftl_restore_complete(restore, restore->pad_status);
+		return true;
+	}
+
+	for (i = 0; i < rband->band->num_zones; ++i) {
+		if (rband->band->zone_buf[i].info.state != SPDK_BDEV_ZONE_STATE_FULL) {
+			num_pad_zones++;
+		}
+	}
+
+	/* Finished all zones in a band, check if all bands are done */
+	if (num_pad_zones == 0) {
+		if (direct_access) {
+			rband->band->state = FTL_BAND_STATE_CLOSED;
+			ftl_band_set_direct_access(rband->band, false);
+		}
+
+		next_band = STAILQ_NEXT(rband, stailq);
+		if (!next_band) {
+			ftl_restore_complete(restore, restore->pad_status);
+			return true;
+		} else {
+			/* Start off padding in the next band */
+			ftl_restore_pad_band(next_band);
+			return true;
+		}
+	}
+
+	return false;
+}
+
+static struct ftl_io *
+ftl_restore_init_pad_io(struct ftl_restore_band *rband, void *buffer,
+			struct ftl_addr addr)
+{
+	struct ftl_band *band = rband->band;
+	struct spdk_ftl_dev *dev = band->dev;
+	int flags = FTL_IO_PAD | FTL_IO_INTERNAL | FTL_IO_PHYSICAL_MODE | FTL_IO_MD |
+		    FTL_IO_DIRECT_ACCESS;
+	struct ftl_io_init_opts opts = {
+		.dev		= dev,
+		.io		= NULL,
+		.band		= band,
+		.size		= sizeof(struct ftl_io),
+		.flags		= flags,
+		.type		= FTL_IO_WRITE,
+		.num_blocks	= dev->xfer_size,
+		.cb_fn		= ftl_pad_zone_cb,
+		.cb_ctx		= rband,
+		.iovs		= {
+			{
+				.iov_base = buffer,
+				.iov_len = dev->xfer_size * FTL_BLOCK_SIZE,
+			}
+		},
+		.iovcnt		= 1,
+		.parent		= NULL,
+	};
+	struct ftl_io *io;
+
+	io = ftl_io_init_internal(&opts);
+	if (spdk_unlikely(!io)) {
+		return NULL;
+	}
+
+	io->addr = addr;
+	rband->parent->num_ios++;
+
+	return io;
+}
+
+static void
+ftl_pad_zone_cb(struct ftl_io *io, void *arg, int status)
+{
+	struct ftl_restore_band *rband = arg;
+	struct ftl_restore *restore = rband->parent;
+	struct ftl_band *band = io->band;
+	struct ftl_zone *zone;
+	struct ftl_io *new_io;
+	uint64_t offset;
+
+	restore->num_ios--;
+	/* TODO check for next unit error vs early close error */
+	if (status) {
+		restore->pad_status = status;
+		goto end;
+	}
+
+	offset = io->addr.offset % ftl_get_num_blocks_in_zone(restore->dev);
+	if (offset + io->num_blocks == ftl_get_num_blocks_in_zone(restore->dev)) {
+		zone = ftl_band_zone_from_addr(band, io->addr);
+		zone->info.state = SPDK_BDEV_ZONE_STATE_FULL;
+	} else {
+		struct ftl_addr addr = io->addr;
+		addr.offset += io->num_blocks;
+		new_io = ftl_restore_init_pad_io(rband, io->iov[0].iov_base, addr);
+		if (spdk_unlikely(!new_io)) {
+			restore->pad_status = -ENOMEM;
+			goto end;
+		}
+
+		ftl_io_write(new_io);
+		return;
+	}
+
+end:
+	spdk_dma_free(io->iov[0].iov_base);
+	ftl_pad_zone_pad_finish(rband, true);
+}
+
+static void
+ftl_restore_pad_band(struct ftl_restore_band *rband)
+{
+	struct ftl_restore *restore = rband->parent;
+	struct ftl_band *band = rband->band;
+	struct spdk_ftl_dev *dev = band->dev;
+	void *buffer = NULL;
+	struct ftl_io *io;
+	struct ftl_addr addr;
+	size_t i;
+	int rc = 0;
+
+	/* Check if some zones are not closed */
+	if (ftl_pad_zone_pad_finish(rband, false)) {
+		/*
+		 * If we're here, end meta wasn't recognized, but the whole band is written
+		 * Assume the band was padded and ignore it
+		 */
+		return;
+	}
+
+	band->state = FTL_BAND_STATE_OPEN;
+	rc = ftl_band_set_direct_access(band, true);
+	if (rc) {
+		ftl_restore_complete(restore, rc);
+		return;
+	}
+
+	for (i = 0; i < band->num_zones; ++i) {
+		if (band->zone_buf[i].info.state == SPDK_BDEV_ZONE_STATE_FULL) {
+			continue;
+		}
+
+		addr.offset = band->zone_buf[i].info.write_pointer;
+
+		buffer = spdk_dma_zmalloc(FTL_BLOCK_SIZE * dev->xfer_size, 0, NULL);
+		if (spdk_unlikely(!buffer)) {
+			rc = -ENOMEM;
+			goto error;
+		}
+
+		io = ftl_restore_init_pad_io(rband, buffer, addr);
+		if (spdk_unlikely(!io)) {
+			rc = -ENOMEM;
+			spdk_dma_free(buffer);
+			goto error;
+		}
+
+		ftl_io_write(io);
+	}
+
+	return;
+
+error:
+	restore->pad_status = rc;
+	ftl_pad_zone_pad_finish(rband, true);
+}
+
+static void
+ftl_restore_pad_open_bands(void *ctx)
+{
+	struct ftl_restore *restore = ctx;
+
+	ftl_restore_pad_band(STAILQ_FIRST(&restore->pad_bands));
+}
+
+static void
+ftl_restore_tail_md_cb(struct ftl_io *io, void *ctx, int status)
+{
+	struct ftl_restore_band *rband = ctx;
+	struct ftl_restore *restore = rband->parent;
+	struct spdk_ftl_dev *dev = restore->dev;
+
+	if (status) {
+		if (!dev->conf.allow_open_bands) {
+			SPDK_ERRLOG("%s while restoring tail md in band %u.\n",
+				    spdk_strerror(-status), rband->band->id);
+			ftl_band_release_lba_map(rband->band);
+			ftl_restore_complete(restore, status);
+			return;
+		} else {
+			SPDK_ERRLOG("%s while restoring tail md. Will attempt to pad band %u.\n",
+				    spdk_strerror(-status), rband->band->id);
+			STAILQ_INSERT_TAIL(&restore->pad_bands, rband, stailq);
+		}
+	}
+
+	if (!status && ftl_restore_l2p(rband->band)) {
+		ftl_band_release_lba_map(rband->band);
+		ftl_restore_complete(restore, -ENOTRECOVERABLE);
+		return;
+	}
+	ftl_band_release_lba_map(rband->band);
+
+	rband = ftl_restore_next_band(restore);
+	if (!rband) {
+		if (!STAILQ_EMPTY(&restore->pad_bands)) {
+			spdk_thread_send_msg(ftl_get_core_thread(dev), ftl_restore_pad_open_bands,
+					     restore);
+		} else {
+			ftl_restore_complete(restore, 0);
+		}
+
+		return;
+	}
+
+	ftl_restore_tail_md(rband);
+}
+
+static int
+ftl_restore_tail_md(struct ftl_restore_band *rband)
+{
+	struct ftl_restore *restore = rband->parent;
+	struct ftl_band *band = rband->band;
+
+	if (ftl_band_alloc_lba_map(band)) {
+		SPDK_ERRLOG("Failed to allocate lba map\n");
+		ftl_restore_complete(restore, -ENOMEM);
+		return -ENOMEM;
+	}
+
+	if (ftl_band_read_tail_md(band, band->tail_md_addr, ftl_restore_tail_md_cb, rband)) {
+		SPDK_ERRLOG("Failed to send tail metadata read\n");
+		ftl_restore_complete(restore, -EIO);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+int
+ftl_restore_device(struct ftl_restore *restore, ftl_restore_fn cb, void *cb_arg)
+{
+	struct spdk_ftl_dev *dev = restore->dev;
+	struct ftl_restore_band *rband;
+
+	restore->current = 0;
+	restore->cb = cb;
+	restore->cb_arg = cb_arg;
+	restore->final_phase = dev->nv_cache.bdev_desc == NULL;
+
+	/* If restore_device is called, there must be at least one valid band */
+	rband = ftl_restore_next_band(restore);
+	assert(rband);
+	return ftl_restore_tail_md(rband);
+}