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 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, int 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_SEC;
 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 }