/*
   *  linux/fs/minix/bitmap.c
   *
   *  Copyright (C) 1991, 1992  Linus Torvalds
   */
  
  /*
   * Modified for 680x0 by Hamish Macdonald
   * Fixed for 680x0 by Andreas Schwab
   */
  
  /* bitmap.c contains the code that handles the inode and block bitmaps */
  
  #include "minix.h"

  #include <linux/buffer_head.h>
  #include <linux/bitops.h>

  #include <linux/sched.h>

  static const int nibblemap[] = { 4,3,3,2,3,2,2,1,3,2,2,1,2,1,1,0 };

  static DEFINE_SPINLOCK(bitmap_lock);

  static unsigned long count_free(struct buffer_head *map[], unsigned numblocks, __u32 numbits)
  {
  	unsigned i, j, sum = 0;
  	struct buffer_head *bh;
    
  	for (i=0; i<numblocks-1; i++) {
  		if (!(bh=map[i])) 
  			return(0);

  		for (j=0; j<bh->b_size; j++)

  			sum += nibblemap[bh->b_data[j] & 0xf]
  				+ nibblemap[(bh->b_data[j]>>4) & 0xf];
  	}
  
  	if (numblocks==0 || !(bh=map[numblocks-1]))
  		return(0);

  	i = ((numbits - (numblocks-1) * bh->b_size * 8) / 16) * 2;

  	for (j=0; j<i; j++) {
  		sum += nibblemap[bh->b_data[j] & 0xf]
  			+ nibblemap[(bh->b_data[j]>>4) & 0xf];
  	}
  
  	i = numbits%16;
  	if (i!=0) {
  		i = *(__u16 *)(&bh->b_data[j]) | ~((1<<i) - 1);
  		sum += nibblemap[i & 0xf] + nibblemap[(i>>4) & 0xf];
  		sum += nibblemap[(i>>8) & 0xf] + nibblemap[(i>>12) & 0xf];
  	}
  	return(sum);
  }

  void minix_free_block(struct inode *inode, unsigned long block)

  {

  	struct super_block *sb = inode->i_sb;
  	struct minix_sb_info *sbi = minix_sb(sb);
  	struct buffer_head *bh;
  	int k = sb->s_blocksize_bits + 3;
  	unsigned long bit, zone;

  
  	if (block < sbi->s_firstdatazone || block >= sbi->s_nzones) {

  		printk("Trying to free block not in datazone
  ");

  		return;
  	}
  	zone = block - sbi->s_firstdatazone + 1;

  	bit = zone & ((1<<k) - 1);
  	zone >>= k;

  	if (zone >= sbi->s_zmap_blocks) {
  		printk("minix_free_block: nonexistent bitmap buffer
  ");
  		return;
  	}
  	bh = sbi->s_zmap[zone];

  	spin_lock(&bitmap_lock);

  	if (!minix_test_and_clear_bit(bit, bh->b_data))
  		printk("minix_free_block (%s:%lu): bit already cleared
  ",

  		       sb->s_id, block);

  	spin_unlock(&bitmap_lock);

  	mark_buffer_dirty(bh);
  	return;
  }
  
  int minix_new_block(struct inode * inode)
  {
  	struct minix_sb_info *sbi = minix_sb(inode->i_sb);

  	int bits_per_zone = 8 * inode->i_sb->s_blocksize;

  	int i;
  
  	for (i = 0; i < sbi->s_zmap_blocks; i++) {
  		struct buffer_head *bh = sbi->s_zmap[i];
  		int j;

  		spin_lock(&bitmap_lock);

  		j = minix_find_first_zero_bit(bh->b_data, bits_per_zone);
  		if (j < bits_per_zone) {
  			minix_set_bit(j, bh->b_data);

  			spin_unlock(&bitmap_lock);

  			mark_buffer_dirty(bh);

  			j += i * bits_per_zone + sbi->s_firstdatazone-1;

  			if (j < sbi->s_firstdatazone || j >= sbi->s_nzones)
  				break;
  			return j;
  		}

  		spin_unlock(&bitmap_lock);

  	}
  	return 0;
  }
  
  unsigned long minix_count_free_blocks(struct minix_sb_info *sbi)
  {
  	return (count_free(sbi->s_zmap, sbi->s_zmap_blocks,
  		sbi->s_nzones - sbi->s_firstdatazone + 1)
  		<< sbi->s_log_zone_size);
  }
  
  struct minix_inode *
  minix_V1_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
  {
  	int block;
  	struct minix_sb_info *sbi = minix_sb(sb);
  	struct minix_inode *p;
  
  	if (!ino || ino > sbi->s_ninodes) {
  		printk("Bad inode number on dev %s: %ld is out of range
  ",
  		       sb->s_id, (long)ino);
  		return NULL;
  	}
  	ino--;
  	block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
  		 ino / MINIX_INODES_PER_BLOCK;
  	*bh = sb_bread(sb, block);
  	if (!*bh) {

  		printk("Unable to read inode block
  ");

  		return NULL;
  	}
  	p = (void *)(*bh)->b_data;
  	return p + ino % MINIX_INODES_PER_BLOCK;
  }
  
  struct minix2_inode *
  minix_V2_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
  {
  	int block;
  	struct minix_sb_info *sbi = minix_sb(sb);
  	struct minix2_inode *p;

  	int minix2_inodes_per_block = sb->s_blocksize / sizeof(struct minix2_inode);

  
  	*bh = NULL;
  	if (!ino || ino > sbi->s_ninodes) {
  		printk("Bad inode number on dev %s: %ld is out of range
  ",
  		       sb->s_id, (long)ino);
  		return NULL;
  	}
  	ino--;
  	block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +

  		 ino / minix2_inodes_per_block;

  	*bh = sb_bread(sb, block);
  	if (!*bh) {

  		printk("Unable to read inode block
  ");

  		return NULL;
  	}
  	p = (void *)(*bh)->b_data;

  	return p + ino % minix2_inodes_per_block;

  }
  
  /* Clear the link count and mode of a deleted inode on disk. */
  
  static void minix_clear_inode(struct inode *inode)
  {
  	struct buffer_head *bh = NULL;
  
  	if (INODE_VERSION(inode) == MINIX_V1) {
  		struct minix_inode *raw_inode;
  		raw_inode = minix_V1_raw_inode(inode->i_sb, inode->i_ino, &bh);
  		if (raw_inode) {
  			raw_inode->i_nlinks = 0;
  			raw_inode->i_mode = 0;
  		}
  	} else {
  		struct minix2_inode *raw_inode;
  		raw_inode = minix_V2_raw_inode(inode->i_sb, inode->i_ino, &bh);
  		if (raw_inode) {
  			raw_inode->i_nlinks = 0;
  			raw_inode->i_mode = 0;
  		}
  	}
  	if (bh) {
  		mark_buffer_dirty(bh);
  		brelse (bh);
  	}
  }
  
  void minix_free_inode(struct inode * inode)
  {

  	struct super_block *sb = inode->i_sb;

  	struct minix_sb_info *sbi = minix_sb(inode->i_sb);

  	struct buffer_head *bh;
  	int k = sb->s_blocksize_bits + 3;
  	unsigned long ino, bit;

  
  	ino = inode->i_ino;
  	if (ino < 1 || ino > sbi->s_ninodes) {
  		printk("minix_free_inode: inode 0 or nonexistent inode
  ");

  		return;

  	}

  	bit = ino & ((1<<k) - 1);
  	ino >>= k;
  	if (ino >= sbi->s_imap_blocks) {

  		printk("minix_free_inode: nonexistent imap in superblock
  ");

  		return;

  	}
  
  	minix_clear_inode(inode);	/* clear on-disk copy */

  	bh = sbi->s_imap[ino];

  	spin_lock(&bitmap_lock);

  	if (!minix_test_and_clear_bit(bit, bh->b_data))
  		printk("minix_free_inode: bit %lu already cleared
  ", bit);

  	spin_unlock(&bitmap_lock);

  	mark_buffer_dirty(bh);

  }

  struct inode *minix_new_inode(const struct inode *dir, int mode, int *error)

  {
  	struct super_block *sb = dir->i_sb;
  	struct minix_sb_info *sbi = minix_sb(sb);
  	struct inode *inode = new_inode(sb);
  	struct buffer_head * bh;

  	int bits_per_zone = 8 * sb->s_blocksize;
  	unsigned long j;
  	int i;

  
  	if (!inode) {
  		*error = -ENOMEM;
  		return NULL;
  	}

  	j = bits_per_zone;

  	bh = NULL;
  	*error = -ENOSPC;

  	spin_lock(&bitmap_lock);

  	for (i = 0; i < sbi->s_imap_blocks; i++) {
  		bh = sbi->s_imap[i];

  		j = minix_find_first_zero_bit(bh->b_data, bits_per_zone);
  		if (j < bits_per_zone)

  			break;
  	}

  	if (!bh || j >= bits_per_zone) {

  		spin_unlock(&bitmap_lock);

  		iput(inode);
  		return NULL;
  	}

  	if (minix_test_and_set_bit(j, bh->b_data)) {	/* shouldn't happen */

  		spin_unlock(&bitmap_lock);

  		printk("minix_new_inode: bit already set
  ");

  		iput(inode);
  		return NULL;
  	}

  	spin_unlock(&bitmap_lock);

  	mark_buffer_dirty(bh);

  	j += i * bits_per_zone;

  	if (!j || j > sbi->s_ninodes) {
  		iput(inode);
  		return NULL;
  	}

  	inode_init_owner(inode, dir, mode);

  	inode->i_ino = j;
  	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;

  	inode->i_blocks = 0;

  	memset(&minix_i(inode)->u, 0, sizeof(minix_i(inode)->u));
  	insert_inode_hash(inode);
  	mark_inode_dirty(inode);
  
  	*error = 0;
  	return inode;
  }
  
  unsigned long minix_count_free_inodes(struct minix_sb_info *sbi)
  {
  	return count_free(sbi->s_imap, sbi->s_imap_blocks, sbi->s_ninodes + 1);
  }