/*
   * 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 <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 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 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 = bitmap_prepare_for_write,
  	.check = 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 bitmap_word_used(void *addr, unsigned 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 sm_lookup_bitmap(void *addr, unsigned b)
  {
  	__le64 *words_le = addr;
  	__le64 *w_le = words_le + (b >> ENTRIES_SHIFT);
  	unsigned 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 b, unsigned 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 begin, unsigned end,
  			unsigned *result)
  {
  	while (begin < end) {
  		if (!(begin & (ENTRIES_PER_WORD - 1)) &&
  		    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)
  {
  	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 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));
  
  		r = dm_tm_unlock(ll->tm, b);
  		if (r < 0)
  			return r;
  
  		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;
  
  	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);
  
  	return dm_tm_unlock(ll->tm, blk);
  }
  
  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);
  
  	for (i = index_begin; i < index_end; i++, begin = 0) {
  		struct dm_block *blk;
  		unsigned 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, 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;
  
  		} else if (r < 0) {
  			dm_tm_unlock(ll->tm, blk);
  			return r;
  		}
  
  		r = dm_tm_unlock(ll->tm, blk);
  		if (r < 0)
  			return r;
  
  		*result = i * ll->entries_per_block + (dm_block_t) position;
  		return 0;
  	}
  
  	return -ENOSPC;
  }
  
  static int sm_ll_mutate(struct ll_disk *ll, dm_block_t b,
  			int (*mutator)(void *context, uint32_t old, uint32_t *new),
  			void *context, enum allocation_event *ev)
  {
  	int r;
  	uint32_t bit, old, ref_count;
  	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;
  		}
  	}
  
  	r = mutator(context, old, &ref_count);
  	if (r) {
  		dm_tm_unlock(ll->tm, nb);
  		return r;
  	}
  
  	if (ref_count <= 2) {
  		sm_set_bitmap(bm_le, bit, ref_count);
  
  		r = dm_tm_unlock(ll->tm, nb);
  		if (r < 0)
  			return r;
  
  		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);
  		r = dm_tm_unlock(ll->tm, nb);
  		if (r < 0)
  			return r;
  
  		__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) {
  		*ev = SM_ALLOC;
  		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) {
  		*ev = SM_FREE;
  		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));
  	}
  
  	return ll->save_ie(ll, index, &ie_disk);
  }
  
  static int set_ref_count(void *context, uint32_t old, uint32_t *new)
  {
  	*new = *((uint32_t *) context);
  	return 0;
  }
  
  int sm_ll_insert(struct ll_disk *ll, dm_block_t b,
  		 uint32_t ref_count, enum allocation_event *ev)
  {
  	return sm_ll_mutate(ll, b, set_ref_count, &ref_count, ev);
  }
  
  static int inc_ref_count(void *context, uint32_t old, uint32_t *new)
  {
  	*new = old + 1;
  	return 0;
  }
  
  int sm_ll_inc(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev)
  {
  	return sm_ll_mutate(ll, b, inc_ref_count, NULL, ev);
  }
  
  static int dec_ref_count(void *context, uint32_t old, uint32_t *new)
  {
  	if (!old) {
  		DMERR_LIMIT("unable to decrement a reference count below 0");
  		return -EINVAL;
  	}
  
  	*new = old - 1;
  	return 0;
  }
  
  int sm_ll_dec(struct ll_disk *ll, dm_block_t b, enum allocation_event *ev)
  {
  	return sm_ll_mutate(ll, b, dec_ref_count, NULL, ev);
  }
  
  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;
  
  	memcpy(dm_block_data(b), &ll->mi_le, sizeof(ll->mi_le));
  	ll->bitmap_root = dm_block_location(b);
  
  	return dm_tm_unlock(ll->tm, b);
  }
  
  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));
  	return dm_tm_unlock(ll->tm, block);
  }
  
  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);
  
  	return dm_tm_unlock(ll->tm, b);
  }
  
  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 = 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 = 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 int disk_ll_load_ie(struct ll_disk *ll, dm_block_t index,
  			   struct disk_index_entry *ie)
  {
  	return dm_btree_lookup(&ll->bitmap_info, ll->bitmap_root, &index, ie);
  }
  
  static int disk_ll_save_ie(struct ll_disk *ll, dm_block_t index,
  			   struct disk_index_entry *ie)
  {
  	__dm_bless_for_disk(ie);
  	return dm_btree_insert(&ll->bitmap_info, ll->bitmap_root,
  			       &index, ie, &ll->bitmap_root);
  }
  
  static int disk_ll_init_index(struct ll_disk *ll)
  {
  	return dm_btree_empty(&ll->bitmap_info, &ll->bitmap_root);
  }
  
  static int disk_ll_open(struct ll_disk *ll)
  {
  	/* nothing to do */
  	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)
  {
  	return 0;
  }
  
  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);
  }
  
  /*----------------------------------------------------------------*/