fs/minix/bitmap.c

   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/smp_lock.h>
  16 #include <linux/buffer_head.h>
  17 #include <linux/bitops.h>
  18 #include <linux/sched.h>
  19
  20 static int nibblemap[] = { 4,3,3,2,3,2,2,1,3,2,2,1,2,1,1,0 };
  21
  22 static unsigned long count_free(struct buffer_head *map[], unsigned numblocks, __u32 numbits)
  23 {
  24         unsigned i, j, sum = 0;
  25         struct buffer_head *bh;
  26
  27         for (i=0; i<numblocks-1; i++) {
  28                 if (!(bh=map[i]))
  29                         return(0);
  30                 for (j=0; j<bh->b_size; j++)
  31                         sum += nibblemap[bh->b_data[j] & 0xf]
  32                                 + nibblemap[(bh->b_data[j]>>4) & 0xf];
  33         }
  34
  35         if (numblocks==0 || !(bh=map[numblocks-1]))
  36                 return(0);
  37         i = ((numbits - (numblocks-1) * bh->b_size * 8) / 16) * 2;
  38         for (j=0; j<i; j++) {
  39                 sum += nibblemap[bh->b_data[j] & 0xf]
  40                         + nibblemap[(bh->b_data[j]>>4) & 0xf];
  41         }
  42
  43         i = numbits%16;
  44         if (i!=0) {
  45                 i = *(__u16 *)(&bh->b_data[j]) | ~((1<<i) - 1);
  46                 sum += nibblemap[i & 0xf] + nibblemap[(i>>4) & 0xf];
  47                 sum += nibblemap[(i>>8) & 0xf] + nibblemap[(i>>12) & 0xf];
  48         }
  49         return(sum);
  50 }
  51
  52 void minix_free_block(struct inode *inode, unsigned long block)
  53 {
  54         struct super_block *sb = inode->i_sb;
  55         struct minix_sb_info *sbi = minix_sb(sb);
  56         struct buffer_head *bh;
  57         int k = sb->s_blocksize_bits + 3;
  58         unsigned long bit, zone;
  59
  60         if (block < sbi->s_firstdatazone || block >= sbi->s_nzones) {
  61                 printk("Trying to free block not in datazone\n");
  62                 return;
  63         }
  64         zone = block - sbi->s_firstdatazone + 1;
  65         bit = zone & ((1<<k) - 1);
  66         zone >>= k;
  67         if (zone >= sbi->s_zmap_blocks) {
  68                 printk("minix_free_block: nonexistent bitmap buffer\n");
  69                 return;
  70         }
  71         bh = sbi->s_zmap[zone];
  72         lock_kernel();
  73         if (!minix_test_and_clear_bit(bit, bh->b_data))
  74                 printk("minix_free_block (%s:%lu): bit already cleared\n",
  75                        sb->s_id, block);
  76         unlock_kernel();
  77         mark_buffer_dirty(bh);
  78         return;
  79 }
  80
  81 int minix_new_block(struct inode * inode)
  82 {
  83         struct minix_sb_info *sbi = minix_sb(inode->i_sb);
  84         int bits_per_zone = 8 * inode->i_sb->s_blocksize;
  85         int i;
  86
  87         for (i = 0; i < sbi->s_zmap_blocks; i++) {
  88                 struct buffer_head *bh = sbi->s_zmap[i];
  89                 int j;
  90
  91                 lock_kernel();
  92                 j = minix_find_first_zero_bit(bh->b_data, bits_per_zone);
  93                 if (j < bits_per_zone) {
  94                         minix_set_bit(j, bh->b_data);
  95                         unlock_kernel();
  96                         mark_buffer_dirty(bh);
  97                         j += i * bits_per_zone + sbi->s_firstdatazone-1;
  98                         if (j < sbi->s_firstdatazone || j >= sbi->s_nzones)
  99                                 break;
 100                         return j;
 101                 }
 102                 unlock_kernel();
 103         }
 104         return 0;
 105 }
 106
 107 unsigned long minix_count_free_blocks(struct minix_sb_info *sbi)
 108 {
 109         return (count_free(sbi->s_zmap, sbi->s_zmap_blocks,
 110                 sbi->s_nzones - sbi->s_firstdatazone + 1)
 111                 << sbi->s_log_zone_size);
 112 }
 113
 114 struct minix_inode *
 115 minix_V1_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
 116 {
 117         int block;
 118         struct minix_sb_info *sbi = minix_sb(sb);
 119         struct minix_inode *p;
 120
 121         if (!ino || ino > sbi->s_ninodes) {
 122                 printk("Bad inode number on dev %s: %ld is out of range\n",
 123                        sb->s_id, (long)ino);
 124                 return NULL;
 125         }
 126         ino--;
 127         block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
 128                  ino / MINIX_INODES_PER_BLOCK;
 129         *bh = sb_bread(sb, block);
 130         if (!*bh) {
 131                 printk("Unable to read inode block\n");
 132                 return NULL;
 133         }
 134         p = (void *)(*bh)->b_data;
 135         return p + ino % MINIX_INODES_PER_BLOCK;
 136 }
 137
 138 struct minix2_inode *
 139 minix_V2_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
 140 {
 141         int block;
 142         struct minix_sb_info *sbi = minix_sb(sb);
 143         struct minix2_inode *p;
 144         int minix2_inodes_per_block = sb->s_blocksize / sizeof(struct minix2_inode);
 145
 146         *bh = NULL;
 147         if (!ino || ino > sbi->s_ninodes) {
 148                 printk("Bad inode number on dev %s: %ld is out of range\n",
 149                        sb->s_id, (long)ino);
 150                 return NULL;
 151         }
 152         ino--;
 153         block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
 154                  ino / minix2_inodes_per_block;
 155         *bh = sb_bread(sb, block);
 156         if (!*bh) {
 157                 printk("Unable to read inode block\n");
 158                 return NULL;
 159         }
 160         p = (void *)(*bh)->b_data;
 161         return p + ino % minix2_inodes_per_block;
 162 }
 163
 164 /* Clear the link count and mode of a deleted inode on disk. */
 165
 166 static void minix_clear_inode(struct inode *inode)
 167 {
 168         struct buffer_head *bh = NULL;
 169
 170         if (INODE_VERSION(inode) == MINIX_V1) {
 171                 struct minix_inode *raw_inode;
 172                 raw_inode = minix_V1_raw_inode(inode->i_sb, inode->i_ino, &bh);
 173                 if (raw_inode) {
 174                         raw_inode->i_nlinks = 0;
 175                         raw_inode->i_mode = 0;
 176                 }
 177         } else {
 178                 struct minix2_inode *raw_inode;
 179                 raw_inode = minix_V2_raw_inode(inode->i_sb, inode->i_ino, &bh);
 180                 if (raw_inode) {
 181                         raw_inode->i_nlinks = 0;
 182                         raw_inode->i_mode = 0;
 183                 }
 184         }
 185         if (bh) {
 186                 mark_buffer_dirty(bh);
 187                 brelse (bh);
 188         }
 189 }
 190
 191 void minix_free_inode(struct inode * inode)
 192 {
 193         struct super_block *sb = inode->i_sb;
 194         struct minix_sb_info *sbi = minix_sb(inode->i_sb);
 195         struct buffer_head *bh;
 196         int k = sb->s_blocksize_bits + 3;
 197         unsigned long ino, bit;
 198
 199         ino = inode->i_ino;
 200         if (ino < 1 || ino > sbi->s_ninodes) {
 201                 printk("minix_free_inode: inode 0 or nonexistent inode\n");
 202                 goto out;
 203         }
 204         bit = ino & ((1<<k) - 1);
 205         ino >>= k;
 206         if (ino >= sbi->s_imap_blocks) {
 207                 printk("minix_free_inode: nonexistent imap in superblock\n");
 208                 goto out;
 209         }
 210
 211         minix_clear_inode(inode);       /* clear on-disk copy */
 212
 213         bh = sbi->s_imap[ino];
 214         lock_kernel();
 215         if (!minix_test_and_clear_bit(bit, bh->b_data))
 216                 printk("minix_free_inode: bit %lu already cleared\n", bit);
 217         unlock_kernel();
 218         mark_buffer_dirty(bh);
 219  out:
 220         clear_inode(inode);             /* clear in-memory copy */
 221 }
 222
 223 struct inode * minix_new_inode(const struct inode * dir, int * error)
 224 {
 225         struct super_block *sb = dir->i_sb;
 226         struct minix_sb_info *sbi = minix_sb(sb);
 227         struct inode *inode = new_inode(sb);
 228         struct buffer_head * bh;
 229         int bits_per_zone = 8 * sb->s_blocksize;
 230         unsigned long j;
 231         int i;
 232
 233         if (!inode) {
 234                 *error = -ENOMEM;
 235                 return NULL;
 236         }
 237         j = bits_per_zone;
 238         bh = NULL;
 239         *error = -ENOSPC;
 240         lock_kernel();
 241         for (i = 0; i < sbi->s_imap_blocks; i++) {
 242                 bh = sbi->s_imap[i];
 243                 j = minix_find_first_zero_bit(bh->b_data, bits_per_zone);
 244                 if (j < bits_per_zone)
 245                         break;
 246         }
 247         if (!bh || j >= bits_per_zone) {
 248                 unlock_kernel();
 249                 iput(inode);
 250                 return NULL;
 251         }
 252         if (minix_test_and_set_bit(j, bh->b_data)) {    /* shouldn't happen */
 253                 unlock_kernel();
 254                 printk("minix_new_inode: bit already set\n");
 255                 iput(inode);
 256                 return NULL;
 257         }
 258         unlock_kernel();
 259         mark_buffer_dirty(bh);
 260         j += i * bits_per_zone;
 261         if (!j || j > sbi->s_ninodes) {
 262                 iput(inode);
 263                 return NULL;
 264         }
 265         inode->i_uid = current->fsuid;
 266         inode->i_gid = (dir->i_mode & S_ISGID) ? dir->i_gid : current->fsgid;
 267         inode->i_ino = j;
 268         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
 269         inode->i_blocks = 0;
 270         memset(&minix_i(inode)->u, 0, sizeof(minix_i(inode)->u));
 271         insert_inode_hash(inode);
 272         mark_inode_dirty(inode);
 273
 274         *error = 0;
 275         return inode;
 276 }
 277
 278 unsigned long minix_count_free_inodes(struct minix_sb_info *sbi)
 279 {
 280         return count_free(sbi->s_imap, sbi->s_imap_blocks, sbi->s_ninodes + 1);
 281 }