| 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 | } |