Adding upstream version 6.1.76.upstream/6.1.76upstream

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

1 files changed, 1259 insertions, 0 deletions

diff --git a/drivers/md/persistent-data/dm-space-map-common.c b/drivers/md/persistent-data/dm-space-map-common.c
new file mode 100644
index 000000000..af800efed
--- /dev/null
+++ b/drivers/md/persistent-data/dm-space-map-common.c
@@ -0,0 +1,1259 @@
+/*
+ * Copyright (C) 2011 Red Hat, Inc.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-space-map-common.h"
+#include "dm-transaction-manager.h"
+#include "dm-btree-internal.h"
+#include "dm-persistent-data-internal.h"
+
+#include <linux/bitops.h>
+#include <linux/device-mapper.h>
+
+#define DM_MSG_PREFIX "space map common"
+
+/*----------------------------------------------------------------*/
+
+/*
+ * Index validator.
+ */
+#define INDEX_CSUM_XOR 160478
+
+static void index_prepare_for_write(struct dm_block_validator *v,
+				    struct dm_block *b,
+				    size_t block_size)
+{
+	struct disk_metadata_index *mi_le = dm_block_data(b);
+
+	mi_le->blocknr = cpu_to_le64(dm_block_location(b));
+	mi_le->csum = cpu_to_le32(dm_bm_checksum(&mi_le->padding,
+						 block_size - sizeof(__le32),
+						 INDEX_CSUM_XOR));
+}
+
+static int index_check(struct dm_block_validator *v,
+		       struct dm_block *b,
+		       size_t block_size)
+{
+	struct disk_metadata_index *mi_le = dm_block_data(b);
+	__le32 csum_disk;
+
+	if (dm_block_location(b) != le64_to_cpu(mi_le->blocknr)) {
+		DMERR_LIMIT("index_check failed: blocknr %llu != wanted %llu",
+			    le64_to_cpu(mi_le->blocknr), dm_block_location(b));
+		return -ENOTBLK;
+	}
+
+	csum_disk = cpu_to_le32(dm_bm_checksum(&mi_le->padding,
+					       block_size - sizeof(__le32),
+					       INDEX_CSUM_XOR));
+	if (csum_disk != mi_le->csum) {
+		DMERR_LIMIT("index_check failed: csum %u != wanted %u",
+			    le32_to_cpu(csum_disk), le32_to_cpu(mi_le->csum));
+		return -EILSEQ;
+	}
+
+	return 0;
+}
+
+static struct dm_block_validator index_validator = {
+	.name = "index",
+	.prepare_for_write = index_prepare_for_write,
+	.check = index_check
+};
+
+/*----------------------------------------------------------------*/
+
+/*
+ * Bitmap validator
+ */
+#define BITMAP_CSUM_XOR 240779
+
+static void dm_bitmap_prepare_for_write(struct dm_block_validator *v,
+					struct dm_block *b,
+					size_t block_size)
+{
+	struct disk_bitmap_header *disk_header = dm_block_data(b);
+
+	disk_header->blocknr = cpu_to_le64(dm_block_location(b));
+	disk_header->csum = cpu_to_le32(dm_bm_checksum(&disk_header->not_used,
+						       block_size - sizeof(__le32),
+						       BITMAP_CSUM_XOR));
+}
+
+static int dm_bitmap_check(struct dm_block_validator *v,
+			   struct dm_block *b,
+			   size_t block_size)
+{
+	struct disk_bitmap_header *disk_header = dm_block_data(b);
+	__le32 csum_disk;
+
+	if (dm_block_location(b) != le64_to_cpu(disk_header->blocknr)) {
+		DMERR_LIMIT("bitmap check failed: blocknr %llu != wanted %llu",
+			    le64_to_cpu(disk_header->blocknr), dm_block_location(b));
+		return -ENOTBLK;
+	}
+
+	csum_disk = cpu_to_le32(dm_bm_checksum(&disk_header->not_used,
+					       block_size - sizeof(__le32),
+					       BITMAP_CSUM_XOR));
+	if (csum_disk != disk_header->csum) {
+		DMERR_LIMIT("bitmap check failed: csum %u != wanted %u",
+			    le32_to_cpu(csum_disk), le32_to_cpu(disk_header->csum));
+		return -EILSEQ;
+	}
+
+	return 0;
+}
+
+static struct dm_block_validator dm_sm_bitmap_validator = {
+	.name = "sm_bitmap",
+	.prepare_for_write = dm_bitmap_prepare_for_write,
+	.check = dm_bitmap_check,
+};
+
+/*----------------------------------------------------------------*/
+
+#define ENTRIES_PER_WORD 32
+#define ENTRIES_SHIFT	5
+
+static void *dm_bitmap_data(struct dm_block *b)
+{
+	return dm_block_data(b) + sizeof(struct disk_bitmap_header);
+}
+
+#define WORD_MASK_HIGH 0xAAAAAAAAAAAAAAAAULL
+
+static unsigned int dm_bitmap_word_used(void *addr, unsigned int b)
+{
+	__le64 *words_le = addr;
+	__le64 *w_le = words_le + (b >> ENTRIES_SHIFT);
+
+	uint64_t bits = le64_to_cpu(*w_le);
+	uint64_t mask = (bits + WORD_MASK_HIGH + 1) & WORD_MASK_HIGH;
+
+	return !(~bits & mask);
+}
+
+static unsigned int sm_lookup_bitmap(void *addr, unsigned int b)
+{
+	__le64 *words_le = addr;
+	__le64 *w_le = words_le + (b >> ENTRIES_SHIFT);
+	unsigned int hi, lo;
+
+	b = (b & (ENTRIES_PER_WORD - 1)) << 1;
+	hi = !!test_bit_le(b, (void *) w_le);
+	lo = !!test_bit_le(b + 1, (void *) w_le);
+	return (hi << 1) | lo;
+}
+
+static void sm_set_bitmap(void *addr, unsigned int b, unsigned int val)
+{
+	__le64 *words_le = addr;
+	__le64 *w_le = words_le + (b >> ENTRIES_SHIFT);
+
+	b = (b & (ENTRIES_PER_WORD - 1)) << 1;
+
+	if (val & 2)
+		__set_bit_le(b, (void *) w_le);
+	else
+		__clear_bit_le(b, (void *) w_le);
+
+	if (val & 1)
+		__set_bit_le(b + 1, (void *) w_le);
+	else
+		__clear_bit_le(b + 1, (void *) w_le);
+}
+
+static int sm_find_free(void *addr, unsigned int begin, unsigned int end,
+			unsigned int *result)
+{
+	while (begin < end) {
+		if (!(begin & (ENTRIES_PER_WORD - 1)) &&
+		    dm_bitmap_word_used(addr, begin)) {
+			begin += ENTRIES_PER_WORD;
+			continue;
+		}
+
+		if (!sm_lookup_bitmap(addr, begin)) {
+			*result = begin;
+			return 0;
+		}
+
+		begin++;
+	}
+
+	return -ENOSPC;
+}
+
+/*----------------------------------------------------------------*/
+
+static int sm_ll_init(struct ll_disk *ll, struct dm_transaction_manager *tm)
+{
+	memset(ll, 0, sizeof(struct ll_disk));
+
+	ll->tm = tm;
+
+	ll->bitmap_info.tm = tm;
+	ll->bitmap_info.levels = 1;
+
+	/*
+	 * Because the new bitmap blocks are created via a shadow
+	 * operation, the old entry has already had its reference count
+	 * decremented and we don't need the btree to do any bookkeeping.
+	 */
+	ll->bitmap_info.value_type.size = sizeof(struct disk_index_entry);
+	ll->bitmap_info.value_type.inc = NULL;
+	ll->bitmap_info.value_type.dec = NULL;
+	ll->bitmap_info.value_type.equal = NULL;
+
+	ll->ref_count_info.tm = tm;
+	ll->ref_count_info.levels = 1;
+	ll->ref_count_info.value_type.size = sizeof(uint32_t);
+	ll->ref_count_info.value_type.inc = NULL;
+	ll->ref_count_info.value_type.dec = NULL;
+	ll->ref_count_info.value_type.equal = NULL;
+
+	ll->block_size = dm_bm_block_size(dm_tm_get_bm(tm));
+
+	if (ll->block_size > (1 << 30)) {
+		DMERR("block size too big to hold bitmaps");
+		return -EINVAL;
+	}
+
+	ll->entries_per_block = (ll->block_size - sizeof(struct disk_bitmap_header)) *
+		ENTRIES_PER_BYTE;
+	ll->nr_blocks = 0;
+	ll->bitmap_root = 0;
+	ll->ref_count_root = 0;
+	ll->bitmap_index_changed = false;
+
+	return 0;
+}
+
+int sm_ll_extend(struct ll_disk *ll, dm_block_t extra_blocks)
+{
+	int r;
+	dm_block_t i, nr_blocks, nr_indexes;
+	unsigned int old_blocks, blocks;
+
+	nr_blocks = ll->nr_blocks + extra_blocks;
+	old_blocks = dm_sector_div_up(ll->nr_blocks, ll->entries_per_block);
+	blocks = dm_sector_div_up(nr_blocks, ll->entries_per_block);
+
+	nr_indexes = dm_sector_div_up(nr_blocks, ll->entries_per_block);
+	if (nr_indexes > ll->max_entries(ll)) {
+		DMERR("space map too large");
+		return -EINVAL;
+	}
+
+	/*
+	 * We need to set this before the dm_tm_new_block() call below.
+	 */
+	ll->nr_blocks = nr_blocks;
+	for (i = old_blocks; i < blocks; i++) {
+		struct dm_block *b;
+		struct disk_index_entry idx;
+
+		r = dm_tm_new_block(ll->tm, &dm_sm_bitmap_validator, &b);
+		if (r < 0)
+			return r;
+
+		idx.blocknr = cpu_to_le64(dm_block_location(b));
+
+		dm_tm_unlock(ll->tm, b);
+
+		idx.nr_free = cpu_to_le32(ll->entries_per_block);
+		idx.none_free_before = 0;
+
+		r = ll->save_ie(ll, i, &idx);
+		if (r < 0)
+			return r;
+	}
+
+	return 0;
+}
+
+int sm_ll_lookup_bitmap(struct ll_disk *ll, dm_block_t b, uint32_t *result)
+{
+	int r;
+	dm_block_t index = b;
+	struct disk_index_entry ie_disk;
+	struct dm_block *blk;
+
+	if (b >= ll->nr_blocks) {
+		DMERR_LIMIT("metadata block out of bounds");
+		return -EINVAL;
+	}
+
+	b = do_div(index, ll->entries_per_block);
+	r = ll->load_ie(ll, index, &ie_disk);
+	if (r < 0)
+		return r;
+
+	r = dm_tm_read_lock(ll->tm, le64_to_cpu(ie_disk.blocknr),
+			    &dm_sm_bitmap_validator, &blk);
+	if (r < 0)
+		return r;
+
+	*result = sm_lookup_bitmap(dm_bitmap_data(blk), b);
+
+	dm_tm_unlock(ll->tm, blk);
+
+	return 0;
+}
+
+static int sm_ll_lookup_big_ref_count(struct ll_disk *ll, dm_block_t b,
+				      uint32_t *result)
+{
+	__le32 le_rc;
+	int r;
+
+	r = dm_btree_lookup(&ll->ref_count_info, ll->ref_count_root, &b, &le_rc);
+	if (r < 0)
+		return r;
+
+	*result = le32_to_cpu(le_rc);
+
+	return r;
+}
+
+int sm_ll_lookup(struct ll_disk *ll, dm_block_t b, uint32_t *result)
+{
+	int r = sm_ll_lookup_bitmap(ll, b, result);
+
+	if (r)
+		return r;
+
+	if (*result != 3)
+		return r;
+
+	return sm_ll_lookup_big_ref_count(ll, b, result);
+}
+
+int sm_ll_find_free_block(struct ll_disk *ll, dm_block_t begin,
+			  dm_block_t end, dm_block_t *result)
+{
+	int r;
+	struct disk_index_entry ie_disk;
+	dm_block_t i, index_begin = begin;
+	dm_block_t index_end = dm_sector_div_up(end, ll->entries_per_block);
+
+	/*
+	 * FIXME: Use shifts
+	 */
+	begin = do_div(index_begin, ll->entries_per_block);
+	end = do_div(end, ll->entries_per_block);
+	if (end == 0)
+		end = ll->entries_per_block;
+
+	for (i = index_begin; i < index_end; i++, begin = 0) {
+		struct dm_block *blk;
+		unsigned int position;
+		uint32_t bit_end;
+
+		r = ll->load_ie(ll, i, &ie_disk);
+		if (r < 0)
+			return r;
+
+		if (le32_to_cpu(ie_disk.nr_free) == 0)
+			continue;
+
+		r = dm_tm_read_lock(ll->tm, le64_to_cpu(ie_disk.blocknr),
+				    &dm_sm_bitmap_validator, &blk);
+		if (r < 0)
+			return r;
+
+		bit_end = (i == index_end - 1) ?  end : ll->entries_per_block;
+
+		r = sm_find_free(dm_bitmap_data(blk),
+				 max_t(unsigned int, begin, le32_to_cpu(ie_disk.none_free_before)),
+				 bit_end, &position);
+		if (r == -ENOSPC) {
+			/*
+			 * This might happen because we started searching
+			 * part way through the bitmap.
+			 */
+			dm_tm_unlock(ll->tm, blk);
+			continue;
+		}
+
+		dm_tm_unlock(ll->tm, blk);
+
+		*result = i * ll->entries_per_block + (dm_block_t) position;
+		return 0;
+	}
+
+	return -ENOSPC;
+}
+
+int sm_ll_find_common_free_block(struct ll_disk *old_ll, struct ll_disk *new_ll,
+	                         dm_block_t begin, dm_block_t end, dm_block_t *b)
+{
+	int r;
+	uint32_t count;
+
+	do {
+		r = sm_ll_find_free_block(new_ll, begin, new_ll->nr_blocks, b);
+		if (r)
+			break;
+
+		/* double check this block wasn't used in the old transaction */
+		if (*b >= old_ll->nr_blocks)
+			count = 0;
+		else {
+			r = sm_ll_lookup(old_ll, *b, &count);
+			if (r)
+				break;
+
+			if (count)
+				begin = *b + 1;
+		}
+	} while (count);
+
+	return r;
+}
+
+/*----------------------------------------------------------------*/
+
+int sm_ll_insert(struct ll_disk *ll, dm_block_t b,
+		 uint32_t ref_count, int32_t *nr_allocations)
+{
+	int r;
+	uint32_t bit, old;
+	struct dm_block *nb;
+	dm_block_t index = b;
+	struct disk_index_entry ie_disk;
+	void *bm_le;
+	int inc;
+
+	bit = do_div(index, ll->entries_per_block);
+	r = ll->load_ie(ll, index, &ie_disk);
+	if (r < 0)
+		return r;
+
+	r = dm_tm_shadow_block(ll->tm, le64_to_cpu(ie_disk.blocknr),
+			       &dm_sm_bitmap_validator, &nb, &inc);
+	if (r < 0) {
+		DMERR("dm_tm_shadow_block() failed");
+		return r;
+	}
+	ie_disk.blocknr = cpu_to_le64(dm_block_location(nb));
+	bm_le = dm_bitmap_data(nb);
+
+	old = sm_lookup_bitmap(bm_le, bit);
+	if (old > 2) {
+		r = sm_ll_lookup_big_ref_count(ll, b, &old);
+		if (r < 0) {
+			dm_tm_unlock(ll->tm, nb);
+			return r;
+		}
+	}
+
+	if (r) {
+		dm_tm_unlock(ll->tm, nb);
+		return r;
+	}
+
+	if (ref_count <= 2) {
+		sm_set_bitmap(bm_le, bit, ref_count);
+		dm_tm_unlock(ll->tm, nb);
+
+		if (old > 2) {
+			r = dm_btree_remove(&ll->ref_count_info,
+					    ll->ref_count_root,
+					    &b, &ll->ref_count_root);
+			if (r)
+				return r;
+		}
+
+	} else {
+		__le32 le_rc = cpu_to_le32(ref_count);
+
+		sm_set_bitmap(bm_le, bit, 3);
+		dm_tm_unlock(ll->tm, nb);
+
+		__dm_bless_for_disk(&le_rc);
+		r = dm_btree_insert(&ll->ref_count_info, ll->ref_count_root,
+				    &b, &le_rc, &ll->ref_count_root);
+		if (r < 0) {
+			DMERR("ref count insert failed");
+			return r;
+		}
+	}
+
+	if (ref_count && !old) {
+		*nr_allocations = 1;
+		ll->nr_allocated++;
+		le32_add_cpu(&ie_disk.nr_free, -1);
+		if (le32_to_cpu(ie_disk.none_free_before) == bit)
+			ie_disk.none_free_before = cpu_to_le32(bit + 1);
+
+	} else if (old && !ref_count) {
+		*nr_allocations = -1;
+		ll->nr_allocated--;
+		le32_add_cpu(&ie_disk.nr_free, 1);
+		ie_disk.none_free_before = cpu_to_le32(min(le32_to_cpu(ie_disk.none_free_before), bit));
+	} else
+		*nr_allocations = 0;
+
+	return ll->save_ie(ll, index, &ie_disk);
+}
+
+/*----------------------------------------------------------------*/
+
+/*
+ * Holds useful intermediate results for the range based inc and dec
+ * operations.
+ */
+struct inc_context {
+	struct disk_index_entry ie_disk;
+	struct dm_block *bitmap_block;
+	void *bitmap;
+
+	struct dm_block *overflow_leaf;
+};
+
+static inline void init_inc_context(struct inc_context *ic)
+{
+	ic->bitmap_block = NULL;
+	ic->bitmap = NULL;
+	ic->overflow_leaf = NULL;
+}
+
+static inline void exit_inc_context(struct ll_disk *ll, struct inc_context *ic)
+{
+	if (ic->bitmap_block)
+		dm_tm_unlock(ll->tm, ic->bitmap_block);
+	if (ic->overflow_leaf)
+		dm_tm_unlock(ll->tm, ic->overflow_leaf);
+}
+
+static inline void reset_inc_context(struct ll_disk *ll, struct inc_context *ic)
+{
+	exit_inc_context(ll, ic);
+	init_inc_context(ic);
+}
+
+/*
+ * Confirms a btree node contains a particular key at an index.
+ */
+static bool contains_key(struct btree_node *n, uint64_t key, int index)
+{
+	return index >= 0 &&
+		index < le32_to_cpu(n->header.nr_entries) &&
+		le64_to_cpu(n->keys[index]) == key;
+}
+
+static int __sm_ll_inc_overflow(struct ll_disk *ll, dm_block_t b, struct inc_context *ic)
+{
+	int r;
+	int index;
+	struct btree_node *n;
+	__le32 *v_ptr;
+	uint32_t rc;
+
+	/*
+	 * bitmap_block needs to be unlocked because getting the
+	 * overflow_leaf may need to allocate, and thus use the space map.
+	 */
+	reset_inc_context(ll, ic);
+
+	r = btree_get_overwrite_leaf(&ll->ref_count_info, ll->ref_count_root,
+				     b, &index, &ll->ref_count_root, &ic->overflow_leaf);
+	if (r < 0)
+		return r;
+
+	n = dm_block_data(ic->overflow_leaf);
+
+	if (!contains_key(n, b, index)) {
+		DMERR("overflow btree is missing an entry");
+		return -EINVAL;
+	}
+
+	v_ptr = value_ptr(n, index);
+	rc = le32_to_cpu(*v_ptr) + 1;
+	*v_ptr = cpu_to_le32(rc);
+
+	return 0;
+}
+
+static int sm_ll_inc_overflow(struct ll_disk *ll, dm_block_t b, struct inc_context *ic)
+{
+	int index;
+	struct btree_node *n;
+	__le32 *v_ptr;
+	uint32_t rc;
+
+	/*
+	 * Do we already have the correct overflow leaf?
+	 */
+	if (ic->overflow_leaf) {
+		n = dm_block_data(ic->overflow_leaf);
+		index = lower_bound(n, b);
+		if (contains_key(n, b, index)) {
+			v_ptr = value_ptr(n, index);
+			rc = le32_to_cpu(*v_ptr) + 1;
+			*v_ptr = cpu_to_le32(rc);
+
+			return 0;
+		}
+	}
+
+	return __sm_ll_inc_overflow(ll, b, ic);
+}
+
+static inline int shadow_bitmap(struct ll_disk *ll, struct inc_context *ic)
+{
+	int r, inc;
+	r = dm_tm_shadow_block(ll->tm, le64_to_cpu(ic->ie_disk.blocknr),
+			       &dm_sm_bitmap_validator, &ic->bitmap_block, &inc);
+	if (r < 0) {
+		DMERR("dm_tm_shadow_block() failed");
+		return r;
+	}
+	ic->ie_disk.blocknr = cpu_to_le64(dm_block_location(ic->bitmap_block));
+	ic->bitmap = dm_bitmap_data(ic->bitmap_block);
+	return 0;
+}
+
+/*
+ * Once shadow_bitmap has been called, which always happens at the start of inc/dec,
+ * we can reopen the bitmap with a simple write lock, rather than re calling
+ * dm_tm_shadow_block().
+ */
+static inline int ensure_bitmap(struct ll_disk *ll, struct inc_context *ic)
+{
+	if (!ic->bitmap_block) {
+		int r = dm_bm_write_lock(dm_tm_get_bm(ll->tm), le64_to_cpu(ic->ie_disk.blocknr),
+					 &dm_sm_bitmap_validator, &ic->bitmap_block);
+		if (r) {
+			DMERR("unable to re-get write lock for bitmap");
+			return r;
+		}
+		ic->bitmap = dm_bitmap_data(ic->bitmap_block);
+	}
+
+	return 0;
+}
+
+/*
+ * Loops round incrementing entries in a single bitmap.
+ */
+static inline int sm_ll_inc_bitmap(struct ll_disk *ll, dm_block_t b,
+				   uint32_t bit, uint32_t bit_end,
+				   int32_t *nr_allocations, dm_block_t *new_b,
+				   struct inc_context *ic)
+{
+	int r;
+	__le32 le_rc;
+	uint32_t old;
+
+	for (; bit != bit_end; bit++, b++) {
+		/*
+		 * We only need to drop the bitmap if we need to find a new btree
+		 * leaf for the overflow.  So if it was dropped last iteration,
+		 * we now re-get it.
+		 */
+		r = ensure_bitmap(ll, ic);
+		if (r)
+			return r;
+
+		old = sm_lookup_bitmap(ic->bitmap, bit);
+		switch (old) {
+		case 0:
+			/* inc bitmap, adjust nr_allocated */
+			sm_set_bitmap(ic->bitmap, bit, 1);
+			(*nr_allocations)++;
+			ll->nr_allocated++;
+			le32_add_cpu(&ic->ie_disk.nr_free, -1);
+			if (le32_to_cpu(ic->ie_disk.none_free_before) == bit)
+				ic->ie_disk.none_free_before = cpu_to_le32(bit + 1);
+			break;
+
+		case 1:
+			/* inc bitmap */
+			sm_set_bitmap(ic->bitmap, bit, 2);
+			break;
+
+		case 2:
+			/* inc bitmap and insert into overflow */
+			sm_set_bitmap(ic->bitmap, bit, 3);
+			reset_inc_context(ll, ic);
+
+			le_rc = cpu_to_le32(3);
+			__dm_bless_for_disk(&le_rc);
+			r = dm_btree_insert(&ll->ref_count_info, ll->ref_count_root,
+					    &b, &le_rc, &ll->ref_count_root);
+			if (r < 0) {
+				DMERR("ref count insert failed");
+				return r;
+			}
+			break;
+
+		default:
+			/*
+			 * inc within the overflow tree only.
+			 */
+			r = sm_ll_inc_overflow(ll, b, ic);
+			if (r < 0)
+				return r;
+		}
+	}
+
+	*new_b = b;
+	return 0;
+}
+
+/*
+ * Finds a bitmap that contains entries in the block range, and increments
+ * them.
+ */
+static int __sm_ll_inc(struct ll_disk *ll, dm_block_t b, dm_block_t e,
+		       int32_t *nr_allocations, dm_block_t *new_b)
+{
+	int r;
+	struct inc_context ic;
+	uint32_t bit, bit_end;
+	dm_block_t index = b;
+
+	init_inc_context(&ic);
+
+	bit = do_div(index, ll->entries_per_block);
+	r = ll->load_ie(ll, index, &ic.ie_disk);
+	if (r < 0)
+		return r;
+
+	r = shadow_bitmap(ll, &ic);
+	if (r)
+		return r;
+
+	bit_end = min(bit + (e - b), (dm_block_t) ll->entries_per_block);
+	r = sm_ll_inc_bitmap(ll, b, bit, bit_end, nr_allocations, new_b, &ic);
+
+	exit_inc_context(ll, &ic);
+
+	if (r)
+		return r;
+
+	return ll->save_ie(ll, index, &ic.ie_disk);
+}
+
+int sm_ll_inc(struct ll_disk *ll, dm_block_t b, dm_block_t e,
+	      int32_t *nr_allocations)
+{
+	*nr_allocations = 0;
+	while (b != e) {
+		int r = __sm_ll_inc(ll, b, e, nr_allocations, &b);
+		if (r)
+			return r;
+	}
+
+	return 0;
+}
+
+/*----------------------------------------------------------------*/
+
+static int __sm_ll_del_overflow(struct ll_disk *ll, dm_block_t b,
+				struct inc_context *ic)
+{
+	reset_inc_context(ll, ic);
+	return dm_btree_remove(&ll->ref_count_info, ll->ref_count_root,
+			       &b, &ll->ref_count_root);
+}
+
+static int __sm_ll_dec_overflow(struct ll_disk *ll, dm_block_t b,
+				struct inc_context *ic, uint32_t *old_rc)
+{
+	int r;
+	int index = -1;
+	struct btree_node *n;
+	__le32 *v_ptr;
+	uint32_t rc;
+
+	reset_inc_context(ll, ic);
+	r = btree_get_overwrite_leaf(&ll->ref_count_info, ll->ref_count_root,
+				     b, &index, &ll->ref_count_root, &ic->overflow_leaf);
+	if (r < 0)
+		return r;
+
+	n = dm_block_data(ic->overflow_leaf);
+
+	if (!contains_key(n, b, index)) {
+		DMERR("overflow btree is missing an entry");
+		return -EINVAL;
+	}
+
+	v_ptr = value_ptr(n, index);
+	rc = le32_to_cpu(*v_ptr);
+	*old_rc = rc;
+
+	if (rc == 3) {
+		return __sm_ll_del_overflow(ll, b, ic);
+	} else {
+		rc--;
+		*v_ptr = cpu_to_le32(rc);
+		return 0;
+	}
+}
+
+static int sm_ll_dec_overflow(struct ll_disk *ll, dm_block_t b,
+			      struct inc_context *ic, uint32_t *old_rc)
+{
+	/*
+	 * Do we already have the correct overflow leaf?
+	 */
+	if (ic->overflow_leaf) {
+		int index;
+		struct btree_node *n;
+		__le32 *v_ptr;
+		uint32_t rc;
+
+		n = dm_block_data(ic->overflow_leaf);
+		index = lower_bound(n, b);
+		if (contains_key(n, b, index)) {
+			v_ptr = value_ptr(n, index);
+			rc = le32_to_cpu(*v_ptr);
+			*old_rc = rc;
+
+			if (rc > 3) {
+				rc--;
+				*v_ptr = cpu_to_le32(rc);
+				return 0;
+			} else {
+				return __sm_ll_del_overflow(ll, b, ic);
+			}
+
+		}
+	}
+
+	return __sm_ll_dec_overflow(ll, b, ic, old_rc);
+}
+
+/*
+ * Loops round incrementing entries in a single bitmap.
+ */
+static inline int sm_ll_dec_bitmap(struct ll_disk *ll, dm_block_t b,
+				   uint32_t bit, uint32_t bit_end,
+				   struct inc_context *ic,
+				   int32_t *nr_allocations, dm_block_t *new_b)
+{
+	int r;
+	uint32_t old;
+
+	for (; bit != bit_end; bit++, b++) {
+		/*
+		 * We only need to drop the bitmap if we need to find a new btree
+		 * leaf for the overflow.  So if it was dropped last iteration,
+		 * we now re-get it.
+		 */
+		r = ensure_bitmap(ll, ic);
+		if (r)
+			return r;
+
+		old = sm_lookup_bitmap(ic->bitmap, bit);
+		switch (old) {
+		case 0:
+			DMERR("unable to decrement block");
+			return -EINVAL;
+
+		case 1:
+			/* dec bitmap */
+			sm_set_bitmap(ic->bitmap, bit, 0);
+			(*nr_allocations)--;
+			ll->nr_allocated--;
+			le32_add_cpu(&ic->ie_disk.nr_free, 1);
+			ic->ie_disk.none_free_before =
+				cpu_to_le32(min(le32_to_cpu(ic->ie_disk.none_free_before), bit));
+			break;
+
+		case 2:
+			/* dec bitmap and insert into overflow */
+			sm_set_bitmap(ic->bitmap, bit, 1);
+			break;
+
+		case 3:
+			r = sm_ll_dec_overflow(ll, b, ic, &old);
+			if (r < 0)
+				return r;
+
+			if (old == 3) {
+				r = ensure_bitmap(ll, ic);
+				if (r)
+					return r;
+
+				sm_set_bitmap(ic->bitmap, bit, 2);
+			}
+			break;
+		}
+	}
+
+	*new_b = b;
+	return 0;
+}
+
+static int __sm_ll_dec(struct ll_disk *ll, dm_block_t b, dm_block_t e,
+		       int32_t *nr_allocations, dm_block_t *new_b)
+{
+	int r;
+	uint32_t bit, bit_end;
+	struct inc_context ic;
+	dm_block_t index = b;
+
+	init_inc_context(&ic);
+
+	bit = do_div(index, ll->entries_per_block);
+	r = ll->load_ie(ll, index, &ic.ie_disk);
+	if (r < 0)
+		return r;
+
+	r = shadow_bitmap(ll, &ic);
+	if (r)
+		return r;
+
+	bit_end = min(bit + (e - b), (dm_block_t) ll->entries_per_block);
+	r = sm_ll_dec_bitmap(ll, b, bit, bit_end, &ic, nr_allocations, new_b);
+	exit_inc_context(ll, &ic);
+
+	if (r)
+		return r;
+
+	return ll->save_ie(ll, index, &ic.ie_disk);
+}
+
+int sm_ll_dec(struct ll_disk *ll, dm_block_t b, dm_block_t e,
+	      int32_t *nr_allocations)
+{
+	*nr_allocations = 0;
+	while (b != e) {
+		int r = __sm_ll_dec(ll, b, e, nr_allocations, &b);
+		if (r)
+			return r;
+	}
+
+	return 0;
+}
+
+/*----------------------------------------------------------------*/
+
+int sm_ll_commit(struct ll_disk *ll)
+{
+	int r = 0;
+
+	if (ll->bitmap_index_changed) {
+		r = ll->commit(ll);
+		if (!r)
+			ll->bitmap_index_changed = false;
+	}
+
+	return r;
+}
+
+/*----------------------------------------------------------------*/
+
+static int metadata_ll_load_ie(struct ll_disk *ll, dm_block_t index,
+			       struct disk_index_entry *ie)
+{
+	memcpy(ie, ll->mi_le.index + index, sizeof(*ie));
+	return 0;
+}
+
+static int metadata_ll_save_ie(struct ll_disk *ll, dm_block_t index,
+			       struct disk_index_entry *ie)
+{
+	ll->bitmap_index_changed = true;
+	memcpy(ll->mi_le.index + index, ie, sizeof(*ie));
+	return 0;
+}
+
+static int metadata_ll_init_index(struct ll_disk *ll)
+{
+	int r;
+	struct dm_block *b;
+
+	r = dm_tm_new_block(ll->tm, &index_validator, &b);
+	if (r < 0)
+		return r;
+
+	ll->bitmap_root = dm_block_location(b);
+
+	dm_tm_unlock(ll->tm, b);
+
+	return 0;
+}
+
+static int metadata_ll_open(struct ll_disk *ll)
+{
+	int r;
+	struct dm_block *block;
+
+	r = dm_tm_read_lock(ll->tm, ll->bitmap_root,
+			    &index_validator, &block);
+	if (r)
+		return r;
+
+	memcpy(&ll->mi_le, dm_block_data(block), sizeof(ll->mi_le));
+	dm_tm_unlock(ll->tm, block);
+
+	return 0;
+}
+
+static dm_block_t metadata_ll_max_entries(struct ll_disk *ll)
+{
+	return MAX_METADATA_BITMAPS;
+}
+
+static int metadata_ll_commit(struct ll_disk *ll)
+{
+	int r, inc;
+	struct dm_block *b;
+
+	r = dm_tm_shadow_block(ll->tm, ll->bitmap_root, &index_validator, &b, &inc);
+	if (r)
+		return r;
+
+	memcpy(dm_block_data(b), &ll->mi_le, sizeof(ll->mi_le));
+	ll->bitmap_root = dm_block_location(b);
+
+	dm_tm_unlock(ll->tm, b);
+
+	return 0;
+}
+
+int sm_ll_new_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm)
+{
+	int r;
+
+	r = sm_ll_init(ll, tm);
+	if (r < 0)
+		return r;
+
+	ll->load_ie = metadata_ll_load_ie;
+	ll->save_ie = metadata_ll_save_ie;
+	ll->init_index = metadata_ll_init_index;
+	ll->open_index = metadata_ll_open;
+	ll->max_entries = metadata_ll_max_entries;
+	ll->commit = metadata_ll_commit;
+
+	ll->nr_blocks = 0;
+	ll->nr_allocated = 0;
+
+	r = ll->init_index(ll);
+	if (r < 0)
+		return r;
+
+	r = dm_btree_empty(&ll->ref_count_info, &ll->ref_count_root);
+	if (r < 0)
+		return r;
+
+	return 0;
+}
+
+int sm_ll_open_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm,
+			void *root_le, size_t len)
+{
+	int r;
+	struct disk_sm_root smr;
+
+	if (len < sizeof(struct disk_sm_root)) {
+		DMERR("sm_metadata root too small");
+		return -ENOMEM;
+	}
+
+	/*
+	 * We don't know the alignment of the root_le buffer, so need to
+	 * copy into a new structure.
+	 */
+	memcpy(&smr, root_le, sizeof(smr));
+
+	r = sm_ll_init(ll, tm);
+	if (r < 0)
+		return r;
+
+	ll->load_ie = metadata_ll_load_ie;
+	ll->save_ie = metadata_ll_save_ie;
+	ll->init_index = metadata_ll_init_index;
+	ll->open_index = metadata_ll_open;
+	ll->max_entries = metadata_ll_max_entries;
+	ll->commit = metadata_ll_commit;
+
+	ll->nr_blocks = le64_to_cpu(smr.nr_blocks);
+	ll->nr_allocated = le64_to_cpu(smr.nr_allocated);
+	ll->bitmap_root = le64_to_cpu(smr.bitmap_root);
+	ll->ref_count_root = le64_to_cpu(smr.ref_count_root);
+
+	return ll->open_index(ll);
+}
+
+/*----------------------------------------------------------------*/
+
+static inline int ie_cache_writeback(struct ll_disk *ll, struct ie_cache *iec)
+{
+	iec->dirty = false;
+	__dm_bless_for_disk(iec->ie);
+	return dm_btree_insert(&ll->bitmap_info, ll->bitmap_root,
+			       &iec->index, &iec->ie, &ll->bitmap_root);
+}
+
+static inline unsigned int hash_index(dm_block_t index)
+{
+	return dm_hash_block(index, IE_CACHE_MASK);
+}
+
+static int disk_ll_load_ie(struct ll_disk *ll, dm_block_t index,
+			   struct disk_index_entry *ie)
+{
+	int r;
+	unsigned int h = hash_index(index);
+	struct ie_cache *iec = ll->ie_cache + h;
+
+	if (iec->valid) {
+		if (iec->index == index) {
+			memcpy(ie, &iec->ie, sizeof(*ie));
+			return 0;
+		}
+
+		if (iec->dirty) {
+			r = ie_cache_writeback(ll, iec);
+			if (r)
+				return r;
+		}
+	}
+
+	r = dm_btree_lookup(&ll->bitmap_info, ll->bitmap_root, &index, ie);
+	if (!r) {
+		iec->valid = true;
+		iec->dirty = false;
+		iec->index = index;
+		memcpy(&iec->ie, ie, sizeof(*ie));
+	}
+
+	return r;
+}
+
+static int disk_ll_save_ie(struct ll_disk *ll, dm_block_t index,
+			   struct disk_index_entry *ie)
+{
+	int r;
+	unsigned int h = hash_index(index);
+	struct ie_cache *iec = ll->ie_cache + h;
+
+	ll->bitmap_index_changed = true;
+	if (iec->valid) {
+		if (iec->index == index) {
+			memcpy(&iec->ie, ie, sizeof(*ie));
+			iec->dirty = true;
+			return 0;
+		}
+
+		if (iec->dirty) {
+			r = ie_cache_writeback(ll, iec);
+			if (r)
+				return r;
+		}
+	}
+
+	iec->valid = true;
+	iec->dirty = true;
+	iec->index = index;
+	memcpy(&iec->ie, ie, sizeof(*ie));
+	return 0;
+}
+
+static int disk_ll_init_index(struct ll_disk *ll)
+{
+	unsigned int i;
+	for (i = 0; i < IE_CACHE_SIZE; i++) {
+		struct ie_cache *iec = ll->ie_cache + i;
+		iec->valid = false;
+		iec->dirty = false;
+	}
+	return dm_btree_empty(&ll->bitmap_info, &ll->bitmap_root);
+}
+
+static int disk_ll_open(struct ll_disk *ll)
+{
+	return 0;
+}
+
+static dm_block_t disk_ll_max_entries(struct ll_disk *ll)
+{
+	return -1ULL;
+}
+
+static int disk_ll_commit(struct ll_disk *ll)
+{
+	int r = 0;
+	unsigned int i;
+
+	for (i = 0; i < IE_CACHE_SIZE; i++) {
+		struct ie_cache *iec = ll->ie_cache + i;
+		if (iec->valid && iec->dirty)
+			r = ie_cache_writeback(ll, iec);
+	}
+
+	return r;
+}
+
+int sm_ll_new_disk(struct ll_disk *ll, struct dm_transaction_manager *tm)
+{
+	int r;
+
+	r = sm_ll_init(ll, tm);
+	if (r < 0)
+		return r;
+
+	ll->load_ie = disk_ll_load_ie;
+	ll->save_ie = disk_ll_save_ie;
+	ll->init_index = disk_ll_init_index;
+	ll->open_index = disk_ll_open;
+	ll->max_entries = disk_ll_max_entries;
+	ll->commit = disk_ll_commit;
+
+	ll->nr_blocks = 0;
+	ll->nr_allocated = 0;
+
+	r = ll->init_index(ll);
+	if (r < 0)
+		return r;
+
+	r = dm_btree_empty(&ll->ref_count_info, &ll->ref_count_root);
+	if (r < 0)
+		return r;
+
+	return 0;
+}
+
+int sm_ll_open_disk(struct ll_disk *ll, struct dm_transaction_manager *tm,
+		    void *root_le, size_t len)
+{
+	int r;
+	struct disk_sm_root *smr = root_le;
+
+	if (len < sizeof(struct disk_sm_root)) {
+		DMERR("sm_metadata root too small");
+		return -ENOMEM;
+	}
+
+	r = sm_ll_init(ll, tm);
+	if (r < 0)
+		return r;
+
+	ll->load_ie = disk_ll_load_ie;
+	ll->save_ie = disk_ll_save_ie;
+	ll->init_index = disk_ll_init_index;
+	ll->open_index = disk_ll_open;
+	ll->max_entries = disk_ll_max_entries;
+	ll->commit = disk_ll_commit;
+
+	ll->nr_blocks = le64_to_cpu(smr->nr_blocks);
+	ll->nr_allocated = le64_to_cpu(smr->nr_allocated);
+	ll->bitmap_root = le64_to_cpu(smr->bitmap_root);
+	ll->ref_count_root = le64_to_cpu(smr->ref_count_root);
+
+	return ll->open_index(ll);
+}
+
+/*----------------------------------------------------------------*/