LXR linux/fs/minix/bitmap.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *  linux/fs/minix/bitmap.c
   4 *
   5 *  Copyright (C) 1991, 1992  Linus Torvalds
   6 */
   7
   8/*
   9 * Modified for 680x0 by Hamish Macdonald
  10 * Fixed for 680x0 by Andreas Schwab
  11 */
  12
  13/* bitmap.c contains the code that handles the inode and block bitmaps */
  14
  15#include "minix.h"
  16#include <linux/buffer_head.h>
  17#include <linux/bitops.h>
  18#include <linux/sched.h>
  19
  20static DEFINE_SPINLOCK(bitmap_lock);
  21
  22/*
  23 * bitmap consists of blocks filled with 16bit words
  24 * bit set == busy, bit clear == free
  25 * endianness is a mess, but for counting zero bits it really doesn't matter...
  26 */
  27static __u32 count_free(struct buffer_head *map[], unsigned blocksize, __u32 numbits)
  28{
  29        __u32 sum = 0;
  30        unsigned blocks = DIV_ROUND_UP(numbits, blocksize * 8);
  31
  32        while (blocks--) {
  33                unsigned words = blocksize / 2;
  34                __u16 *p = (__u16 *)(*map++)->b_data;
  35                while (words--)
  36                        sum += 16 - hweight16(*p++);
  37        }
  38
  39        return sum;
  40}
  41
  42void minix_free_block(struct inode *inode, unsigned long block)
  43{
  44        struct super_block *sb = inode->i_sb;
  45        struct minix_sb_info *sbi = minix_sb(sb);
  46        struct buffer_head *bh;
  47        int k = sb->s_blocksize_bits + 3;
  48        unsigned long bit, zone;
  49
  50        if (block < sbi->s_firstdatazone || block >= sbi->s_nzones) {
  51                printk("Trying to free block not in datazone\n");
  52                return;
  53        }
  54        zone = block - sbi->s_firstdatazone + 1;
  55        bit = zone & ((1<<k) - 1);
  56        zone >>= k;
  57        if (zone >= sbi->s_zmap_blocks) {
  58                printk("minix_free_block: nonexistent bitmap buffer\n");
  59                return;
  60        }
  61        bh = sbi->s_zmap[zone];
  62        spin_lock(&bitmap_lock);
  63        if (!minix_test_and_clear_bit(bit, bh->b_data))
  64                printk("minix_free_block (%s:%lu): bit already cleared\n",
  65                       sb->s_id, block);
  66        spin_unlock(&bitmap_lock);
  67        mark_buffer_dirty(bh);
  68        return;
  69}
  70
  71int minix_new_block(struct inode * inode)
  72{
  73        struct minix_sb_info *sbi = minix_sb(inode->i_sb);
  74        int bits_per_zone = 8 * inode->i_sb->s_blocksize;
  75        int i;
  76
  77        for (i = 0; i < sbi->s_zmap_blocks; i++) {
  78                struct buffer_head *bh = sbi->s_zmap[i];
  79                int j;
  80
  81                spin_lock(&bitmap_lock);
  82                j = minix_find_first_zero_bit(bh->b_data, bits_per_zone);
  83                if (j < bits_per_zone) {
  84                        minix_set_bit(j, bh->b_data);
  85                        spin_unlock(&bitmap_lock);
  86                        mark_buffer_dirty(bh);
  87                        j += i * bits_per_zone + sbi->s_firstdatazone-1;
  88                        if (j < sbi->s_firstdatazone || j >= sbi->s_nzones)
  89                                break;
  90                        return j;
  91                }
  92                spin_unlock(&bitmap_lock);
  93        }
  94        return 0;
  95}
  96
  97unsigned long minix_count_free_blocks(struct super_block *sb)
  98{
  99        struct minix_sb_info *sbi = minix_sb(sb);
 100        u32 bits = sbi->s_nzones - sbi->s_firstdatazone + 1;
 101
 102        return (count_free(sbi->s_zmap, sb->s_blocksize, bits)
 103                << sbi->s_log_zone_size);
 104}
 105
 106struct minix_inode *
 107minix_V1_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
 108{
 109        int block;
 110        struct minix_sb_info *sbi = minix_sb(sb);
 111        struct minix_inode *p;
 112
 113        if (!ino || ino > sbi->s_ninodes) {
 114                printk("Bad inode number on dev %s: %ld is out of range\n",
 115                       sb->s_id, (long)ino);
 116                return NULL;
 117        }
 118        ino--;
 119        block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
 120                 ino / MINIX_INODES_PER_BLOCK;
 121        *bh = sb_bread(sb, block);
 122        if (!*bh) {
 123                printk("Unable to read inode block\n");
 124                return NULL;
 125        }
 126        p = (void *)(*bh)->b_data;
 127        return p + ino % MINIX_INODES_PER_BLOCK;
 128}
 129
 130struct minix2_inode *
 131minix_V2_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
 132{
 133        int block;
 134        struct minix_sb_info *sbi = minix_sb(sb);
 135        struct minix2_inode *p;
 136        int minix2_inodes_per_block = sb->s_blocksize / sizeof(struct minix2_inode);
 137
 138        *bh = NULL;
 139        if (!ino || ino > sbi->s_ninodes) {
 140                printk("Bad inode number on dev %s: %ld is out of range\n",
 141                       sb->s_id, (long)ino);
 142                return NULL;
 143        }
 144        ino--;
 145        block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
 146                 ino / minix2_inodes_per_block;
 147        *bh = sb_bread(sb, block);
 148        if (!*bh) {
 149                printk("Unable to read inode block\n");
 150                return NULL;
 151        }
 152        p = (void *)(*bh)->b_data;
 153        return p + ino % minix2_inodes_per_block;
 154}
 155
 156/* Clear the link count and mode of a deleted inode on disk. */
 157
 158static void minix_clear_inode(struct inode *inode)
 159{
 160        struct buffer_head *bh = NULL;
 161
 162        if (INODE_VERSION(inode) == MINIX_V1) {
 163                struct minix_inode *raw_inode;
 164                raw_inode = minix_V1_raw_inode(inode->i_sb, inode->i_ino, &bh);
 165                if (raw_inode) {
 166                        raw_inode->i_nlinks = 0;
 167                        raw_inode->i_mode = 0;
 168                }
 169        } else {
 170                struct minix2_inode *raw_inode;
 171                raw_inode = minix_V2_raw_inode(inode->i_sb, inode->i_ino, &bh);
 172                if (raw_inode) {
 173                        raw_inode->i_nlinks = 0;
 174                        raw_inode->i_mode = 0;
 175                }
 176        }
 177        if (bh) {
 178                mark_buffer_dirty(bh);
 179                brelse (bh);
 180        }
 181}
 182
 183void minix_free_inode(struct inode * inode)
 184{
 185        struct super_block *sb = inode->i_sb;
 186        struct minix_sb_info *sbi = minix_sb(inode->i_sb);
 187        struct buffer_head *bh;
 188        int k = sb->s_blocksize_bits + 3;
 189        unsigned long ino, bit;
 190
 191        ino = inode->i_ino;
 192        if (ino < 1 || ino > sbi->s_ninodes) {
 193                printk("minix_free_inode: inode 0 or nonexistent inode\n");
 194                return;
 195        }
 196        bit = ino & ((1<<k) - 1);
 197        ino >>= k;
 198        if (ino >= sbi->s_imap_blocks) {
 199                printk("minix_free_inode: nonexistent imap in superblock\n");
 200                return;
 201        }
 202
 203        minix_clear_inode(inode);       /* clear on-disk copy */
 204
 205        bh = sbi->s_imap[ino];
 206        spin_lock(&bitmap_lock);
 207        if (!minix_test_and_clear_bit(bit, bh->b_data))
 208                printk("minix_free_inode: bit %lu already cleared\n", bit);
 209        spin_unlock(&bitmap_lock);
 210        mark_buffer_dirty(bh);
 211}
 212
 213struct inode *minix_new_inode(const struct inode *dir, umode_t mode, int *error)
 214{
 215        struct super_block *sb = dir->i_sb;
 216        struct minix_sb_info *sbi = minix_sb(sb);
 217        struct inode *inode = new_inode(sb);
 218        struct buffer_head * bh;
 219        int bits_per_zone = 8 * sb->s_blocksize;
 220        unsigned long j;
 221        int i;
 222
 223        if (!inode) {
 224                *error = -ENOMEM;
 225                return NULL;
 226        }
 227        j = bits_per_zone;
 228        bh = NULL;
 229        *error = -ENOSPC;
 230        spin_lock(&bitmap_lock);
 231        for (i = 0; i < sbi->s_imap_blocks; i++) {
 232                bh = sbi->s_imap[i];
 233                j = minix_find_first_zero_bit(bh->b_data, bits_per_zone);
 234                if (j < bits_per_zone)
 235                        break;
 236        }
 237        if (!bh || j >= bits_per_zone) {
 238                spin_unlock(&bitmap_lock);
 239                iput(inode);
 240                return NULL;
 241        }
 242        if (minix_test_and_set_bit(j, bh->b_data)) {    /* shouldn't happen */
 243                spin_unlock(&bitmap_lock);
 244                printk("minix_new_inode: bit already set\n");
 245                iput(inode);
 246                return NULL;
 247        }
 248        spin_unlock(&bitmap_lock);
 249        mark_buffer_dirty(bh);
 250        j += i * bits_per_zone;
 251        if (!j || j > sbi->s_ninodes) {
 252                iput(inode);
 253                return NULL;
 254        }
 255        inode_init_owner(inode, dir, mode);
 256        inode->i_ino = j;
 257        inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
 258        inode->i_blocks = 0;
 259        memset(&minix_i(inode)->u, 0, sizeof(minix_i(inode)->u));
 260        insert_inode_hash(inode);
 261        mark_inode_dirty(inode);
 262
 263        *error = 0;
 264        return inode;
 265}
 266
 267unsigned long minix_count_free_inodes(struct super_block *sb)
 268{
 269        struct minix_sb_info *sbi = minix_sb(sb);
 270        u32 bits = sbi->s_ninodes + 1;
 271
 272        return count_free(sbi->s_imap, sb->s_blocksize, bits);
 273}
 274