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