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 19 static 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 */ 26 static __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 41 void 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 70 int 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 96 unsigned 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 } 104 105 struct minix_inode * 106 minix_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 } 128 129 struct minix2_inode * 130 minix_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. */ 156 157 static 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 } 181 182 void 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 } 211 212 struct 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(inode); 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 } 265 266 unsigned 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