// SPDX-License-Identifier: GPL-2.0-or-later
  /*
   *  Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
   */
  
  #include <linux/blkdev.h>
  #include <linux/slab.h>
  #include <linux/buffer_head.h>
  
  #include "exfat_raw.h"
  #include "exfat_fs.h"
  
  static const unsigned char free_bit[] = {
  	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2,/*  0 ~  19*/
  	0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5, 0, 1, 0, 2, 0, 1, 0, 3,/* 20 ~  39*/
  	0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/* 40 ~  59*/
  	0, 1, 0, 6, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4,/* 60 ~  79*/
  	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5, 0, 1, 0, 2,/* 80 ~  99*/
  	0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3,/*100 ~ 119*/
  	0, 1, 0, 2, 0, 1, 0, 7, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/*120 ~ 139*/
  	0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 5,/*140 ~ 159*/
  	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2,/*160 ~ 179*/
  	0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 6, 0, 1, 0, 2, 0, 1, 0, 3,/*180 ~ 199*/
  	0, 1, 0, 2, 0, 1, 0, 4, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2,/*200 ~ 219*/
  	0, 1, 0, 5, 0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0, 4,/*220 ~ 239*/
  	0, 1, 0, 2, 0, 1, 0, 3, 0, 1, 0, 2, 0, 1, 0                /*240 ~ 254*/
  };
  
  static const unsigned char used_bit[] = {
  	0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, 1, 2, 2, 3,/*  0 ~  19*/
  	2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 1, 2, 2, 3, 2, 3, 3, 4,/* 20 ~  39*/
  	2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5,/* 40 ~  59*/
  	4, 5, 5, 6, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,/* 60 ~  79*/
  	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 2, 3, 3, 4,/* 80 ~  99*/
  	3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6,/*100 ~ 119*/
  	4, 5, 5, 6, 5, 6, 6, 7, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4,/*120 ~ 139*/
  	3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,/*140 ~ 159*/
  	2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5,/*160 ~ 179*/
  	4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 2, 3, 3, 4, 3, 4, 4, 5,/*180 ~ 199*/
  	3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6,/*200 ~ 219*/
  	5, 6, 6, 7, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,/*220 ~ 239*/
  	4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8             /*240 ~ 255*/
  };
  
  /*
   *  Allocation Bitmap Management Functions
   */
  static int exfat_allocate_bitmap(struct super_block *sb,
  		struct exfat_dentry *ep)
  {
  	struct exfat_sb_info *sbi = EXFAT_SB(sb);
  	long long map_size;
  	unsigned int i, need_map_size;
  	sector_t sector;
  
  	sbi->map_clu = le32_to_cpu(ep->dentry.bitmap.start_clu);
  	map_size = le64_to_cpu(ep->dentry.bitmap.size);
  	need_map_size = ((EXFAT_DATA_CLUSTER_COUNT(sbi) - 1) / BITS_PER_BYTE)
  		+ 1;
  	if (need_map_size != map_size) {

  		exfat_err(sb, "bogus allocation bitmap size(need : %u, cur : %lld)",
  			  need_map_size, map_size);

  		/*
  		 * Only allowed when bogus allocation
  		 * bitmap size is large
  		 */
  		if (need_map_size > map_size)
  			return -EIO;
  	}
  	sbi->map_sectors = ((need_map_size - 1) >>
  			(sb->s_blocksize_bits)) + 1;
  	sbi->vol_amap = kmalloc_array(sbi->map_sectors,
  				sizeof(struct buffer_head *), GFP_KERNEL);
  	if (!sbi->vol_amap)
  		return -ENOMEM;
  
  	sector = exfat_cluster_to_sector(sbi, sbi->map_clu);
  	for (i = 0; i < sbi->map_sectors; i++) {
  		sbi->vol_amap[i] = sb_bread(sb, sector + i);
  		if (!sbi->vol_amap[i]) {
  			/* release all buffers and free vol_amap */
  			int j = 0;
  
  			while (j < i)
  				brelse(sbi->vol_amap[j++]);
  
  			kfree(sbi->vol_amap);
  			sbi->vol_amap = NULL;
  			return -EIO;
  		}
  	}

  	return 0;
  }
  
  int exfat_load_bitmap(struct super_block *sb)
  {
  	unsigned int i, type;
  	struct exfat_chain clu;
  	struct exfat_sb_info *sbi = EXFAT_SB(sb);
  
  	exfat_chain_set(&clu, sbi->root_dir, 0, ALLOC_FAT_CHAIN);
  	while (clu.dir != EXFAT_EOF_CLUSTER) {
  		for (i = 0; i < sbi->dentries_per_clu; i++) {
  			struct exfat_dentry *ep;
  			struct buffer_head *bh;
  
  			ep = exfat_get_dentry(sb, &clu, i, &bh, NULL);
  			if (!ep)
  				return -EIO;
  
  			type = exfat_get_entry_type(ep);
  			if (type == TYPE_UNUSED)
  				break;
  			if (type != TYPE_BITMAP)
  				continue;
  			if (ep->dentry.bitmap.flags == 0x0) {
  				int err;
  
  				err = exfat_allocate_bitmap(sb, ep);
  				brelse(bh);
  				return err;
  			}
  			brelse(bh);
  		}
  
  		if (exfat_get_next_cluster(sb, &clu.dir))
  			return -EIO;
  	}
  
  	return -EINVAL;
  }
  
  void exfat_free_bitmap(struct exfat_sb_info *sbi)
  {
  	int i;

  	for (i = 0; i < sbi->map_sectors; i++)
  		__brelse(sbi->vol_amap[i]);
  
  	kfree(sbi->vol_amap);
  }
  
  /*
   * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
   * the cluster heap.
   */
  int exfat_set_bitmap(struct inode *inode, unsigned int clu)
  {
  	int i, b;
  	unsigned int ent_idx;
  	struct super_block *sb = inode->i_sb;
  	struct exfat_sb_info *sbi = EXFAT_SB(sb);
  
  	WARN_ON(clu < EXFAT_FIRST_CLUSTER);
  	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
  	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
  	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
  
  	set_bit_le(b, sbi->vol_amap[i]->b_data);

  	exfat_update_bh(sbi->vol_amap[i], IS_DIRSYNC(inode));

  	return 0;
  }
  
  /*
   * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
   * the cluster heap.
   */
  void exfat_clear_bitmap(struct inode *inode, unsigned int clu)
  {
  	int i, b;
  	unsigned int ent_idx;
  	struct super_block *sb = inode->i_sb;
  	struct exfat_sb_info *sbi = EXFAT_SB(sb);
  	struct exfat_mount_options *opts = &sbi->options;
  
  	WARN_ON(clu < EXFAT_FIRST_CLUSTER);
  	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
  	i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
  	b = BITMAP_OFFSET_BIT_IN_SECTOR(sb, ent_idx);
  
  	clear_bit_le(b, sbi->vol_amap[i]->b_data);

  	exfat_update_bh(sbi->vol_amap[i], IS_DIRSYNC(inode));

  
  	if (opts->discard) {
  		int ret_discard;
  
  		ret_discard = sb_issue_discard(sb,
  			exfat_cluster_to_sector(sbi, clu +
  						EXFAT_RESERVED_CLUSTERS),
  			(1 << sbi->sect_per_clus_bits), GFP_NOFS, 0);
  
  		if (ret_discard == -EOPNOTSUPP) {

  			exfat_err(sb, "discard not supported by device, disabling");

  			opts->discard = 0;
  		}
  	}
  }
  
  /*
   * If the value of "clu" is 0, it means cluster 2 which is the first cluster of
   * the cluster heap.
   */
  unsigned int exfat_find_free_bitmap(struct super_block *sb, unsigned int clu)
  {
  	unsigned int i, map_i, map_b, ent_idx;
  	unsigned int clu_base, clu_free;
  	unsigned char k, clu_mask;
  	struct exfat_sb_info *sbi = EXFAT_SB(sb);
  
  	WARN_ON(clu < EXFAT_FIRST_CLUSTER);
  	ent_idx = CLUSTER_TO_BITMAP_ENT(clu);
  	clu_base = BITMAP_ENT_TO_CLUSTER(ent_idx & ~(BITS_PER_BYTE_MASK));
  	clu_mask = IGNORED_BITS_REMAINED(clu, clu_base);
  
  	map_i = BITMAP_OFFSET_SECTOR_INDEX(sb, ent_idx);
  	map_b = BITMAP_OFFSET_BYTE_IN_SECTOR(sb, ent_idx);
  
  	for (i = EXFAT_FIRST_CLUSTER; i < sbi->num_clusters;
  	     i += BITS_PER_BYTE) {
  		k = *(sbi->vol_amap[map_i]->b_data + map_b);
  		if (clu_mask > 0) {
  			k |= clu_mask;
  			clu_mask = 0;
  		}
  		if (k < 0xFF) {
  			clu_free = clu_base + free_bit[k];
  			if (clu_free < sbi->num_clusters)
  				return clu_free;
  		}
  		clu_base += BITS_PER_BYTE;
  
  		if (++map_b >= sb->s_blocksize ||
  		    clu_base >= sbi->num_clusters) {
  			if (++map_i >= sbi->map_sectors) {
  				clu_base = EXFAT_FIRST_CLUSTER;
  				map_i = 0;
  			}
  			map_b = 0;
  		}
  	}
  
  	return EXFAT_EOF_CLUSTER;
  }
  
  int exfat_count_used_clusters(struct super_block *sb, unsigned int *ret_count)
  {
  	struct exfat_sb_info *sbi = EXFAT_SB(sb);
  	unsigned int count = 0;
  	unsigned int i, map_i = 0, map_b = 0;
  	unsigned int total_clus = EXFAT_DATA_CLUSTER_COUNT(sbi);
  	unsigned int last_mask = total_clus & BITS_PER_BYTE_MASK;
  	unsigned char clu_bits;
  	const unsigned char last_bit_mask[] = {0, 0b00000001, 0b00000011,
  		0b00000111, 0b00001111, 0b00011111, 0b00111111, 0b01111111};
  
  	total_clus &= ~last_mask;
  	for (i = 0; i < total_clus; i += BITS_PER_BYTE) {
  		clu_bits = *(sbi->vol_amap[map_i]->b_data + map_b);
  		count += used_bit[clu_bits];
  		if (++map_b >= (unsigned int)sb->s_blocksize) {
  			map_i++;
  			map_b = 0;
  		}
  	}
  
  	if (last_mask) {
  		clu_bits = *(sbi->vol_amap[map_i]->b_data + map_b);
  		clu_bits &= last_bit_mask[last_mask];
  		count += used_bit[clu_bits];
  	}
  
  	*ret_count = count;
  	return 0;
  }