fs/sysv/balloc.c

   1 /*
   2  *  linux/fs/sysv/balloc.c
   3  *
   4  *  minix/bitmap.c
   5  *  Copyright (C) 1991, 1992  Linus Torvalds
   6  *
   7  *  ext/freelists.c
   8  *  Copyright (C) 1992  Remy Card (card@masi.ibp.fr)
   9  *
  10  *  xenix/alloc.c
  11  *  Copyright (C) 1992  Doug Evans
  12  *
  13  *  coh/alloc.c
  14  *  Copyright (C) 1993  Pascal Haible, Bruno Haible
  15  *
  16  *  sysv/balloc.c
  17  *  Copyright (C) 1993  Bruno Haible
  18  *
  19  *  This file contains code for allocating/freeing blocks.
  20  */
  21
  22 #include <linux/buffer_head.h>
  23 #include <linux/string.h>
  24 #include "sysv.h"
  25
  26 /* We don't trust the value of
  27    sb->sv_sbd2->s_tfree = *sb->sv_free_blocks
  28    but we nevertheless keep it up to date. */
  29
  30 static inline sysv_zone_t *get_chunk(struct super_block *sb, struct buffer_head *bh)
  31 {
  32         char *bh_data = bh->b_data;
  33
  34         if (SYSV_SB(sb)->s_type == FSTYPE_SYSV4)
  35                 return (sysv_zone_t*)(bh_data+4);
  36         else
  37                 return (sysv_zone_t*)(bh_data+2);
  38 }
  39
  40 /* NOTE NOTE NOTE: nr is a block number _as_ _stored_ _on_ _disk_ */
  41
  42 void sysv_free_block(struct super_block * sb, sysv_zone_t nr)
  43 {
  44         struct sysv_sb_info * sbi = SYSV_SB(sb);
  45         struct buffer_head * bh;
  46         sysv_zone_t *blocks = sbi->s_bcache;
  47         unsigned count;
  48         unsigned block = fs32_to_cpu(sbi, nr);
  49
  50         /*
  51          * This code does not work at all for AFS (it has a bitmap
  52          * free list).  As AFS is supposed to be read-only no one
  53          * should call this for an AFS filesystem anyway...
  54          */
  55         if (sbi->s_type == FSTYPE_AFS)
  56                 return;
  57
  58         if (block < sbi->s_firstdatazone || block >= sbi->s_nzones) {
  59                 printk("sysv_free_block: trying to free block not in datazone\n");
  60                 return;
  61         }
  62
  63         lock_super(sb);
  64         count = fs16_to_cpu(sbi, *sbi->s_bcache_count);
  65
  66         if (count > sbi->s_flc_size) {
  67                 printk("sysv_free_block: flc_count > flc_size\n");
  68                 unlock_super(sb);
  69                 return;
  70         }
  71         /* If the free list head in super-block is full, it is copied
  72          * into this block being freed, ditto if it's completely empty
  73          * (applies only on Coherent).
  74          */
  75         if (count == sbi->s_flc_size || count == 0) {
  76                 block += sbi->s_block_base;
  77                 bh = sb_getblk(sb, block);
  78                 if (!bh) {
  79                         printk("sysv_free_block: getblk() failed\n");
  80                         unlock_super(sb);
  81                         return;
  82                 }
  83                 memset(bh->b_data, 0, sb->s_blocksize);
  84                 *(__fs16*)bh->b_data = cpu_to_fs16(sbi, count);
  85                 memcpy(get_chunk(sb,bh), blocks, count * sizeof(sysv_zone_t));
  86                 mark_buffer_dirty(bh);
  87                 set_buffer_uptodate(bh);
  88                 brelse(bh);
  89                 count = 0;
  90         }
  91         sbi->s_bcache[count++] = nr;
  92
  93         *sbi->s_bcache_count = cpu_to_fs16(sbi, count);
  94         fs32_add(sbi, sbi->s_free_blocks, 1);
  95         dirty_sb(sb);
  96         unlock_super(sb);
  97 }
  98
  99 sysv_zone_t sysv_new_block(struct super_block * sb)
 100 {
 101         struct sysv_sb_info *sbi = SYSV_SB(sb);
 102         unsigned int block;
 103         sysv_zone_t nr;
 104         struct buffer_head * bh;
 105         unsigned count;
 106
 107         lock_super(sb);
 108         count = fs16_to_cpu(sbi, *sbi->s_bcache_count);
 109
 110         if (count == 0) /* Applies only to Coherent FS */
 111                 goto Enospc;
 112         nr = sbi->s_bcache[--count];
 113         if (nr == 0)  /* Applies only to Xenix FS, SystemV FS */
 114                 goto Enospc;
 115
 116         block = fs32_to_cpu(sbi, nr);
 117
 118         *sbi->s_bcache_count = cpu_to_fs16(sbi, count);
 119
 120         if (block < sbi->s_firstdatazone || block >= sbi->s_nzones) {
 121                 printk("sysv_new_block: new block %d is not in data zone\n",
 122                         block);
 123                 goto Enospc;
 124         }
 125
 126         if (count == 0) { /* the last block continues the free list */
 127                 unsigned count;
 128
 129                 block += sbi->s_block_base;
 130                 if (!(bh = sb_bread(sb, block))) {
 131                         printk("sysv_new_block: cannot read free-list block\n");
 132                         /* retry this same block next time */
 133                         *sbi->s_bcache_count = cpu_to_fs16(sbi, 1);
 134                         goto Enospc;
 135                 }
 136                 count = fs16_to_cpu(sbi, *(__fs16*)bh->b_data);
 137                 if (count > sbi->s_flc_size) {
 138                         printk("sysv_new_block: free-list block with >flc_size entries\n");
 139                         brelse(bh);
 140                         goto Enospc;
 141                 }
 142                 *sbi->s_bcache_count = cpu_to_fs16(sbi, count);
 143                 memcpy(sbi->s_bcache, get_chunk(sb, bh),
 144                                 count * sizeof(sysv_zone_t));
 145                 brelse(bh);
 146         }
 147         /* Now the free list head in the superblock is valid again. */
 148         fs32_add(sbi, sbi->s_free_blocks, -1);
 149         dirty_sb(sb);
 150         unlock_super(sb);
 151         return nr;
 152
 153 Enospc:
 154         unlock_super(sb);
 155         return 0;
 156 }
 157
 158 unsigned long sysv_count_free_blocks(struct super_block * sb)
 159 {
 160         struct sysv_sb_info * sbi = SYSV_SB(sb);
 161         int sb_count;
 162         int count;
 163         struct buffer_head * bh = NULL;
 164         sysv_zone_t *blocks;
 165         unsigned block;
 166         int n;
 167
 168         /*
 169          * This code does not work at all for AFS (it has a bitmap
 170          * free list).  As AFS is supposed to be read-only we just
 171          * lie and say it has no free block at all.
 172          */
 173         if (sbi->s_type == FSTYPE_AFS)
 174                 return 0;
 175
 176         lock_super(sb);
 177         sb_count = fs32_to_cpu(sbi, *sbi->s_free_blocks);
 178
 179         if (0)
 180                 goto trust_sb;
 181
 182         /* this causes a lot of disk traffic ... */
 183         count = 0;
 184         n = fs16_to_cpu(sbi, *sbi->s_bcache_count);
 185         blocks = sbi->s_bcache;
 186         while (1) {
 187                 sysv_zone_t zone;
 188                 if (n > sbi->s_flc_size)
 189                         goto E2big;
 190                 zone = 0;
 191                 while (n && (zone = blocks[--n]) != 0)
 192                         count++;
 193                 if (zone == 0)
 194                         break;
 195
 196                 block = fs32_to_cpu(sbi, zone);
 197                 if (bh)
 198                         brelse(bh);
 199
 200                 if (block < sbi->s_firstdatazone || block >= sbi->s_nzones)
 201                         goto Einval;
 202                 block += sbi->s_block_base;
 203                 bh = sb_bread(sb, block);
 204                 if (!bh)
 205                         goto Eio;
 206                 n = fs16_to_cpu(sbi, *(__fs16*)bh->b_data);
 207                 blocks = get_chunk(sb, bh);
 208         }
 209         if (bh)
 210                 brelse(bh);
 211         if (count != sb_count)
 212                 goto Ecount;
 213 done:
 214         unlock_super(sb);
 215         return count;
 216
 217 Einval:
 218         printk("sysv_count_free_blocks: new block %d is not in data zone\n",
 219                 block);
 220         goto trust_sb;
 221 Eio:
 222         printk("sysv_count_free_blocks: cannot read free-list block\n");
 223         goto trust_sb;
 224 E2big:
 225         printk("sysv_count_free_blocks: >flc_size entries in free-list block\n");
 226         if (bh)
 227                 brelse(bh);
 228 trust_sb:
 229         count = sb_count;
 230         goto done;
 231 Ecount:
 232         printk("sysv_count_free_blocks: free block count was %d, "
 233                 "correcting to %d\n", sb_count, count);
 234         if (!(sb->s_flags & MS_RDONLY)) {
 235                 *sbi->s_free_blocks = cpu_to_fs32(sbi, count);
 236                 dirty_sb(sb);
 237         }
 238         goto done;
 239 }