// SPDX-License-Identifier: GPL-2.0
/*
 *  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 DEFINE_SPINLOCK(bitmap_lock);

/*
 * bitmap consists of blocks filled with 16bit words
 * bit set == busy, bit clear == free
 * endianness is a mess, but for counting zero bits it really doesn't matter...
 */
static __u32 count_free(struct buffer_head *map[], unsigned blocksize, __u32 numbits)
{
        __u32 sum = 0;
        unsigned blocks = DIV_ROUND_UP(numbits, blocksize * 8);

        while (blocks--) {
                unsigned words = blocksize / 2;
                __u16 *p = (__u16 *)(*map++)->b_data;
                while (words--)
                        sum += 16 - hweight16(*p++);
        }

        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\n");
                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\n");
                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\n",
                       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 super_block *sb)
{
        struct minix_sb_info *sbi = minix_sb(sb);
        u32 bits = sbi->s_nzones - sbi->s_firstdatazone + 1;

        return (count_free(sbi->s_zmap, sb->s_blocksize, bits)
                << 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\n",
                       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\n");
                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\n",
                       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\n");
                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\n");
                return;
        }
        bit = ino & ((1<<k) - 1);
        ino >>= k;
        if (ino >= sbi->s_imap_blocks) {
                printk("minix_free_inode: nonexistent imap in superblock\n");
                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\n", bit);
        spin_unlock(&bitmap_lock);
        mark_buffer_dirty(bh);
}

struct inode *minix_new_inode(const struct inode *dir, umode_t mode)
{
        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)
                return ERR_PTR(-ENOMEM);
        j = bits_per_zone;
        bh = NULL;
        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 ERR_PTR(-ENOSPC);
        }
        if (minix_test_and_set_bit(j, bh->b_data)) {    /* shouldn't happen */
                spin_unlock(&bitmap_lock);
                printk("minix_new_inode: bit already set\n");
                iput(inode);
                return ERR_PTR(-ENOSPC);
        }
        spin_unlock(&bitmap_lock);
        mark_buffer_dirty(bh);
        j += i * bits_per_zone;
        if (!j || j > sbi->s_ninodes) {
                iput(inode);
                return ERR_PTR(-EFSCORRUPTED);
        }
        inode_init_owner(&nop_mnt_idmap, inode, dir, mode);
        inode->i_ino = j;
        simple_inode_init_ts(inode);
        inode->i_blocks = 0;
        memset(&minix_i(inode)->u, 0, sizeof(minix_i(inode)->u));
        insert_inode_hash(inode);
        mark_inode_dirty(inode);

        return inode;
}

unsigned long minix_count_free_inodes(struct super_block *sb)
{
        struct minix_sb_info *sbi = minix_sb(sb);
        u32 bits = sbi->s_ninodes + 1;

        return count_free(sbi->s_imap, sb->s_blocksize, bits);
}