fs/minix/bitmap.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  linux/fs/minix/bitmap.c
   4  *
   5  *  Copyright (C) 1991, 1992  Linus Torvalds
   6  */
   7
   8 /*
   9  * Modified for 680x0 by Hamish Macdonald
  10  * Fixed for 680x0 by Andreas Schwab
  11  */
  12
  13 /* bitmap.c contains the code that handles the inode and block bitmaps */
  14
  15 #include "minix.h"
  16 #include <linux/buffer_head.h>
  17 #include <linux/bitops.h>
  18 #include <linux/sched.h>
  19
  20 static DEFINE_SPINLOCK(bitmap_lock);
  21
  22 /*
  23  * bitmap consists of blocks filled with 16bit words
  24  * bit set == busy, bit clear == free
  25  * endianness is a mess, but for counting zero bits it really doesn't matter...
  26  */
  27 static __u32 count_free(struct buffer_head *map[], unsigned blocksize, __u32 numbits)
  28 {
  29         __u32 sum = 0;
  30         unsigned blocks = DIV_ROUND_UP(numbits, blocksize * 8);
  31
  32         while (blocks--) {
  33                 unsigned words = blocksize / 2;
  34                 __u16 *p = (__u16 *)(*map++)->b_data;
  35                 while (words--)
  36                         sum += 16 - hweight16(*p++);
  37         }
  38
  39         return sum;
  40 }
  41
  42 void minix_free_block(struct inode *inode, unsigned long block)
  43 {
  44         struct super_block *sb = inode->i_sb;
  45         struct minix_sb_info *sbi = minix_sb(sb);
  46         struct buffer_head *bh;
  47         int k = sb->s_blocksize_bits + 3;
  48         unsigned long bit, zone;
  49
  50         if (block < sbi->s_firstdatazone || block >= sbi->s_nzones) {
  51                 printk("Trying to free block not in datazone\n");
  52                 return;
  53         }
  54         zone = block - sbi->s_firstdatazone + 1;
  55         bit = zone & ((1<<k) - 1);
  56         zone >>= k;
  57         if (zone >= sbi->s_zmap_blocks) {
  58                 printk("minix_free_block: nonexistent bitmap buffer\n");
  59                 return;
  60         }
  61         bh = sbi->s_zmap[zone];
  62         spin_lock(&bitmap_lock);
  63         if (!minix_test_and_clear_bit(bit, bh->b_data))
  64                 printk("minix_free_block (%s:%lu): bit already cleared\n",
  65                        sb->s_id, block);
  66         spin_unlock(&bitmap_lock);
  67         mark_buffer_dirty(bh);
  68         return;
  69 }
  70
  71 int minix_new_block(struct inode * inode)
  72 {
  73         struct minix_sb_info *sbi = minix_sb(inode->i_sb);
  74         int bits_per_zone = 8 * inode->i_sb->s_blocksize;
  75         int i;
  76
  77         for (i = 0; i < sbi->s_zmap_blocks; i++) {
  78                 struct buffer_head *bh = sbi->s_zmap[i];
  79                 int j;
  80
  81                 spin_lock(&bitmap_lock);
  82                 j = minix_find_first_zero_bit(bh->b_data, bits_per_zone);
  83                 if (j < bits_per_zone) {
  84                         minix_set_bit(j, bh->b_data);
  85                         spin_unlock(&bitmap_lock);
  86                         mark_buffer_dirty(bh);
  87                         j += i * bits_per_zone + sbi->s_firstdatazone-1;
  88                         if (j < sbi->s_firstdatazone || j >= sbi->s_nzones)
  89                                 break;
  90                         return j;
  91                 }
  92                 spin_unlock(&bitmap_lock);
  93         }
  94         return 0;
  95 }
  96
  97 unsigned long minix_count_free_blocks(struct super_block *sb)
  98 {
  99         struct minix_sb_info *sbi = minix_sb(sb);
 100         u32 bits = sbi->s_nzones - sbi->s_firstdatazone + 1;
 101
 102         return (count_free(sbi->s_zmap, sb->s_blocksize, bits)
 103                 << sbi->s_log_zone_size);
 104 }
 105
 106 struct minix_inode *
 107 minix_V1_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
 108 {
 109         int block;
 110         struct minix_sb_info *sbi = minix_sb(sb);
 111         struct minix_inode *p;
 112
 113         if (!ino || ino > sbi->s_ninodes) {
 114                 printk("Bad inode number on dev %s: %ld is out of range\n",
 115                        sb->s_id, (long)ino);
 116                 return NULL;
 117         }
 118         ino--;
 119         block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
 120                  ino / MINIX_INODES_PER_BLOCK;
 121         *bh = sb_bread(sb, block);
 122         if (!*bh) {
 123                 printk("Unable to read inode block\n");
 124                 return NULL;
 125         }
 126         p = (void *)(*bh)->b_data;
 127         return p + ino % MINIX_INODES_PER_BLOCK;
 128 }
 129
 130 struct minix2_inode *
 131 minix_V2_raw_inode(struct super_block *sb, ino_t ino, struct buffer_head **bh)
 132 {
 133         int block;
 134         struct minix_sb_info *sbi = minix_sb(sb);
 135         struct minix2_inode *p;
 136         int minix2_inodes_per_block = sb->s_blocksize / sizeof(struct minix2_inode);
 137
 138         *bh = NULL;
 139         if (!ino || ino > sbi->s_ninodes) {
 140                 printk("Bad inode number on dev %s: %ld is out of range\n",
 141                        sb->s_id, (long)ino);
 142                 return NULL;
 143         }
 144         ino--;
 145         block = 2 + sbi->s_imap_blocks + sbi->s_zmap_blocks +
 146                  ino / minix2_inodes_per_block;
 147         *bh = sb_bread(sb, block);
 148         if (!*bh) {
 149                 printk("Unable to read inode block\n");
 150                 return NULL;
 151         }
 152         p = (void *)(*bh)->b_data;
 153         return p + ino % minix2_inodes_per_block;
 154 }
 155
 156 /* Clear the link count and mode of a deleted inode on disk. */
 157
 158 static void minix_clear_inode(struct inode *inode)
 159 {
 160         struct buffer_head *bh = NULL;
 161
 162         if (INODE_VERSION(inode) == MINIX_V1) {
 163                 struct minix_inode *raw_inode;
 164                 raw_inode = minix_V1_raw_inode(inode->i_sb, inode->i_ino, &bh);
 165                 if (raw_inode) {
 166                         raw_inode->i_nlinks = 0;
 167                         raw_inode->i_mode = 0;
 168                 }
 169         } else {
 170                 struct minix2_inode *raw_inode;
 171                 raw_inode = minix_V2_raw_inode(inode->i_sb, inode->i_ino, &bh);
 172                 if (raw_inode) {
 173                         raw_inode->i_nlinks = 0;
 174                         raw_inode->i_mode = 0;
 175                 }
 176         }
 177         if (bh) {
 178                 mark_buffer_dirty(bh);
 179                 brelse (bh);
 180         }
 181 }
 182
 183 void minix_free_inode(struct inode * inode)
 184 {
 185         struct super_block *sb = inode->i_sb;
 186         struct minix_sb_info *sbi = minix_sb(inode->i_sb);
 187         struct buffer_head *bh;
 188         int k = sb->s_blocksize_bits + 3;
 189         unsigned long ino, bit;
 190
 191         ino = inode->i_ino;
 192         if (ino < 1 || ino > sbi->s_ninodes) {
 193                 printk("minix_free_inode: inode 0 or nonexistent inode\n");
 194                 return;
 195         }
 196         bit = ino & ((1<<k) - 1);
 197         ino >>= k;
 198         if (ino >= sbi->s_imap_blocks) {
 199                 printk("minix_free_inode: nonexistent imap in superblock\n");
 200                 return;
 201         }
 202
 203         minix_clear_inode(inode);       /* clear on-disk copy */
 204
 205         bh = sbi->s_imap[ino];
 206         spin_lock(&bitmap_lock);
 207         if (!minix_test_and_clear_bit(bit, bh->b_data))
 208                 printk("minix_free_inode: bit %lu already cleared\n", bit);
 209         spin_unlock(&bitmap_lock);
 210         mark_buffer_dirty(bh);
 211 }
 212
 213 struct inode *minix_new_inode(const struct inode *dir, umode_t mode, int *error)
 214 {
 215         struct super_block *sb = dir->i_sb;
 216         struct minix_sb_info *sbi = minix_sb(sb);
 217         struct inode *inode = new_inode(sb);
 218         struct buffer_head * bh;
 219         int bits_per_zone = 8 * sb->s_blocksize;
 220         unsigned long j;
 221         int i;
 222
 223         if (!inode) {
 224                 *error = -ENOMEM;
 225                 return NULL;
 226         }
 227         j = bits_per_zone;
 228         bh = NULL;
 229         *error = -ENOSPC;
 230         spin_lock(&bitmap_lock);
 231         for (i = 0; i < sbi->s_imap_blocks; i++) {
 232                 bh = sbi->s_imap[i];
 233                 j = minix_find_first_zero_bit(bh->b_data, bits_per_zone);
 234                 if (j < bits_per_zone)
 235                         break;
 236         }
 237         if (!bh || j >= bits_per_zone) {
 238                 spin_unlock(&bitmap_lock);
 239                 iput(inode);
 240                 return NULL;
 241         }
 242         if (minix_test_and_set_bit(j, bh->b_data)) {    /* shouldn't happen */
 243                 spin_unlock(&bitmap_lock);
 244                 printk("minix_new_inode: bit already set\n");
 245                 iput(inode);
 246                 return NULL;
 247         }
 248         spin_unlock(&bitmap_lock);
 249         mark_buffer_dirty(bh);
 250         j += i * bits_per_zone;
 251         if (!j || j > sbi->s_ninodes) {
 252                 iput(inode);
 253                 return NULL;
 254         }
 255         inode_init_owner(inode, dir, mode);
 256         inode->i_ino = j;
 257         inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
 258         inode->i_blocks = 0;
 259         memset(&minix_i(inode)->u, 0, sizeof(minix_i(inode)->u));
 260         insert_inode_hash(inode);
 261         mark_inode_dirty(inode);
 262
 263         *error = 0;
 264         return inode;
 265 }
 266
 267 unsigned long minix_count_free_inodes(struct super_block *sb)
 268 {
 269         struct minix_sb_info *sbi = minix_sb(sb);
 270         u32 bits = sbi->s_ninodes + 1;
 271
 272         return count_free(sbi->s_imap, sb->s_blocksize, bits);
 273 }