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/buffer_head.h>
  16 #include <linux/bitops.h>
  17 #include <linux/sched.h>
  18
  19 static const int nibblemap[] = { 4,3,3,2,3,2,2,1,3,2,2,1,2,1,1,0 };
  20
  21 static DEFINE_SPINLOCK(bitmap_lock);
  22
  23 static unsigned long count_free(struct buffer_head *map[], unsigned numblocks, __u32 numbits)
  24 {
  25         unsigned i, j, sum = 0;
  26         struct buffer_head *bh;
  27
  28         for (i=0; i<numblocks-1; i++) {
  29                 if (!(bh=map[i]))
  30                         return(0);
  31                 for (j=0; j<bh->b_size; j++)
  32                         sum += nibblemap[bh->b_data[j] & 0xf]
  33                                 + nibblemap[(bh->b_data[j]>>4) & 0xf];
  34         }
  35
  36         if (numblocks==0 || !(bh=map[numblocks-1]))
  37                 return(0);
  38         i = ((numbits - (numblocks-1) * bh->b_size * 8) / 16) * 2;
  39         for (j=0; j<i; j++) {
  40                 sum += nibblemap[bh->b_data[j] & 0xf]
  41                         + nibblemap[(bh->b_data[j]>>4) & 0xf];
  42         }
  43
  44         i = numbits%16;
  45         if (i!=0) {
  46                 i = *(__u16 *)(&bh->b_data[j]) | ~((1<<i) - 1);
  47                 sum += nibblemap[i & 0xf] + nibblemap[(i>>4) & 0xf];
  48                 sum += nibblemap[(i>>8) & 0xf] + nibblemap[(i>>12) & 0xf];
  49         }
  50         return(sum);
  51 }
  52
  53 void minix_free_block(struct inode *inode, unsigned long block)
  54 {
  55         struct super_block *sb = inode->i_sb;
  56         struct minix_sb_info *sbi = minix_sb(sb);
  57         struct buffer_head *bh;
  58         int k = sb->s_blocksize_bits + 3;
  59         unsigned long bit, zone;
  60
  61         if (block < sbi->s_firstdatazone || block >= sbi->s_nzones) {
  62                 printk("Trying to free block not in datazone\n");
  63                 return;
  64         }
  65         zone = block - sbi->s_firstdatazone + 1;
  66         bit = zone & ((1<<k) - 1);
  67         zone >>= k;
  68         if (zone >= sbi->s_zmap_blocks) {
  69                 printk("minix_free_block: nonexistent bitmap buffer\n");
  70                 return;
  71         }
  72         bh = sbi->s_zmap[zone];
  73         spin_lock(&bitmap_lock);
  74         if (!minix_test_and_clear_bit(bit, bh->b_data))
  75                 printk("minix_free_block (%s:%lu): bit already cleared\n",
  76                        sb->s_id, block);
  77         spin_unlock(&bitmap_lock);
  78         mark_buffer_dirty(bh);
  79         return;
  80 }
  81
  82 int minix_new_block(struct inode * inode)
  83 {
  84         struct minix_sb_info *sbi = minix_sb(inode->i_sb);
  85         int bits_per_zone = 8 * inode->i_sb->s_blocksize;
  86         int i;
  87
  88         for (i = 0; i < sbi->s_zmap_blocks; i++) {
  89                 struct buffer_head *bh = sbi->s_zmap[i];
  90                 int j;
  91
  92                 spin_lock(&bitmap_lock);
  93                 j = minix_find_first_zero_bit(bh->b_data, bits_per_zone);
  94                 if (j < bits_per_zone) {
  95                         minix_set_bit(j, bh->b_data);
  96                         spin_unlock(&bitmap_lock);
  97                         mark_buffer_dirty(bh);
  98                         j += i * bits_per_zone + sbi->s_firstdatazone-1;
  99                         if (j < sbi->s_firstdatazone || j >= sbi->s_nzones)
 100                                 break;
 101                         return j;
 102                 }
 103                 spin_unlock(&bitmap_lock);
 104         }
 105         return 0;
 106 }
 107
 108 unsigned long minix_count_free_blocks(struct minix_sb_info *sbi)
 109 {
 110         return (count_free(sbi->s_zmap, sbi->s_zmap_blocks,
 111                 sbi->s_nzones - sbi->s_firstdatazone + 1)
 112                 << sbi->s_log_zone_size);
 113 }
 114
 115 struct minix_inode *
 116 minix_V1_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
 117 {
 118         int block;
 119         struct minix_sb_info *sbi = minix_sb(sb);
 120         struct minix_inode *p;
 121
 122         if (!ino || ino > sbi->s_ninodes) {
 123                 printk("Bad inode number on dev %s: %ld is out of range\n",
 124                        sb->s_id, (long)ino);
 125                 return NULL;
 126         }
 127         ino--;
 128         block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
 129                  ino / MINIX_INODES_PER_BLOCK;
 130         *bh = sb_bread(sb, block);
 131         if (!*bh) {
 132                 printk("Unable to read inode block\n");
 133                 return NULL;
 134         }
 135         p = (void *)(*bh)->b_data;
 136         return p + ino % MINIX_INODES_PER_BLOCK;
 137 }
 138
 139 struct minix2_inode *
 140 minix_V2_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
 141 {
 142         int block;
 143         struct minix_sb_info *sbi = minix_sb(sb);
 144         struct minix2_inode *p;
 145         int minix2_inodes_per_block = sb->s_blocksize / sizeof(struct minix2_inode);
 146
 147         *bh = NULL;
 148         if (!ino || ino > sbi->s_ninodes) {
 149                 printk("Bad inode number on dev %s: %ld is out of range\n",
 150                        sb->s_id, (long)ino);
 151                 return NULL;
 152         }
 153         ino--;
 154         block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
 155                  ino / minix2_inodes_per_block;
 156         *bh = sb_bread(sb, block);
 157         if (!*bh) {
 158                 printk("Unable to read inode block\n");
 159                 return NULL;
 160         }
 161         p = (void *)(*bh)->b_data;
 162         return p + ino % minix2_inodes_per_block;
 163 }
 164
 165 /* Clear the link count and mode of a deleted inode on disk. */
 166
 167 static void minix_clear_inode(struct inode *inode)
 168 {
 169         struct buffer_head *bh = NULL;
 170
 171         if (INODE_VERSION(inode) == MINIX_V1) {
 172                 struct minix_inode *raw_inode;
 173                 raw_inode = minix_V1_raw_inode(inode->i_sb, inode->i_ino, &bh);
 174                 if (raw_inode) {
 175                         raw_inode->i_nlinks = 0;
 176                         raw_inode->i_mode = 0;
 177                 }
 178         } else {
 179                 struct minix2_inode *raw_inode;
 180                 raw_inode = minix_V2_raw_inode(inode->i_sb, inode->i_ino, &bh);
 181                 if (raw_inode) {
 182                         raw_inode->i_nlinks = 0;
 183                         raw_inode->i_mode = 0;
 184                 }
 185         }
 186         if (bh) {
 187                 mark_buffer_dirty(bh);
 188                 brelse (bh);
 189         }
 190 }
 191
 192 void minix_free_inode(struct inode * inode)
 193 {
 194         struct super_block *sb = inode->i_sb;
 195         struct minix_sb_info *sbi = minix_sb(inode->i_sb);
 196         struct buffer_head *bh;
 197         int k = sb->s_blocksize_bits + 3;
 198         unsigned long ino, bit;
 199
 200         ino = inode->i_ino;
 201         if (ino < 1 || ino > sbi->s_ninodes) {
 202                 printk("minix_free_inode: inode 0 or nonexistent inode\n");
 203                 goto out;
 204         }
 205         bit = ino & ((1<<k) - 1);
 206         ino >>= k;
 207         if (ino >= sbi->s_imap_blocks) {
 208                 printk("minix_free_inode: nonexistent imap in superblock\n");
 209                 goto out;
 210         }
 211
 212         minix_clear_inode(inode);       /* clear on-disk copy */
 213
 214         bh = sbi->s_imap[ino];
 215         spin_lock(&bitmap_lock);
 216         if (!minix_test_and_clear_bit(bit, bh->b_data))
 217                 printk("minix_free_inode: bit %lu already cleared\n", bit);
 218         spin_unlock(&bitmap_lock);
 219         mark_buffer_dirty(bh);
 220  out:
 221         clear_inode(inode);             /* clear in-memory copy */
 222 }
 223
 224 struct inode * minix_new_inode(const struct inode * dir, int * error)
 225 {
 226         struct super_block *sb = dir->i_sb;
 227         struct minix_sb_info *sbi = minix_sb(sb);
 228         struct inode *inode = new_inode(sb);
 229         struct buffer_head * bh;
 230         int bits_per_zone = 8 * sb->s_blocksize;
 231         unsigned long j;
 232         int i;
 233
 234         if (!inode) {
 235                 *error = -ENOMEM;
 236                 return NULL;
 237         }
 238         j = bits_per_zone;
 239         bh = NULL;
 240         *error = -ENOSPC;
 241         spin_lock(&bitmap_lock);
 242         for (i = 0; i < sbi->s_imap_blocks; i++) {
 243                 bh = sbi->s_imap[i];
 244                 j = minix_find_first_zero_bit(bh->b_data, bits_per_zone);
 245                 if (j < bits_per_zone)
 246                         break;
 247         }
 248         if (!bh || j >= bits_per_zone) {
 249                 spin_unlock(&bitmap_lock);
 250                 iput(inode);
 251                 return NULL;
 252         }
 253         if (minix_test_and_set_bit(j, bh->b_data)) {    /* shouldn't happen */
 254                 spin_unlock(&bitmap_lock);
 255                 printk("minix_new_inode: bit already set\n");
 256                 iput(inode);
 257                 return NULL;
 258         }
 259         spin_unlock(&bitmap_lock);
 260         mark_buffer_dirty(bh);
 261         j += i * bits_per_zone;
 262         if (!j || j > sbi->s_ninodes) {
 263                 iput(inode);
 264                 return NULL;
 265         }
 266         inode->i_uid = current_fsuid();
 267         inode->i_gid = (dir->i_mode & S_ISGID) ? dir->i_gid : current_fsgid();
 268         inode->i_ino = j;
 269         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
 270         inode->i_blocks = 0;
 271         memset(&minix_i(inode)->u, 0, sizeof(minix_i(inode)->u));
 272         insert_inode_hash(inode);
 273         mark_inode_dirty(inode);
 274
 275         *error = 0;
 276         return inode;
 277 }
 278
 279 unsigned long minix_count_free_inodes(struct minix_sb_info *sbi)
 280 {
 281         return count_free(sbi->s_imap, sbi->s_imap_blocks, sbi->s_ninodes + 1);
 282 }