fs/qnx4/bitmap.c

   1 /*
   2  * QNX4 file system, Linux implementation.
   3  *
   4  * Version : 0.2.1
   5  *
   6  * Using parts of the xiafs filesystem.
   7  *
   8  * History :
   9  *
  10  * 28-05-1998 by Richard Frowijn : first release.
  11  * 20-06-1998 by Frank Denis : basic optimisations.
  12  * 25-06-1998 by Frank Denis : qnx4_is_free, qnx4_set_bitmap, qnx4_bmap .
  13  * 28-06-1998 by Frank Denis : qnx4_free_inode (to be fixed) .
  14  */
  15
  16 #include <linux/config.h>
  17 #include <linux/sched.h>
  18 #include <linux/qnx4_fs.h>
  19 #include <linux/stat.h>
  20 #include <linux/kernel.h>
  21 #include <linux/string.h>
  22
  23 #include <asm/bitops.h>
  24
  25 int qnx4_new_block(struct super_block *sb)
  26 {
  27         return 0;
  28 }
  29
  30 void count_bits(const register char *bmPart, register int size,
  31                 int *const tf)
  32 {
  33         char b;
  34         int tot = *tf;
  35
  36         if (size > QNX4_BLOCK_SIZE) {
  37                 size = QNX4_BLOCK_SIZE;
  38         }
  39         do {
  40                 b = *bmPart++;
  41                 if ((b & 1) == 0)
  42                         tot++;
  43                 if ((b & 2) == 0)
  44                         tot++;
  45                 if ((b & 4) == 0)
  46                         tot++;
  47                 if ((b & 8) == 0)
  48                         tot++;
  49                 if ((b & 16) == 0)
  50                         tot++;
  51                 if ((b & 32) == 0)
  52                         tot++;
  53                 if ((b & 64) == 0)
  54                         tot++;
  55                 if ((b & 128) == 0)
  56                         tot++;
  57                 size--;
  58         } while (size != 0);
  59         *tf = tot;
  60 }
  61
  62 unsigned long qnx4_count_free_blocks(struct super_block *sb)
  63 {
  64         int start = le32_to_cpu(sb->u.qnx4_sb.BitMap->di_first_xtnt.xtnt_blk) - 1;
  65         int total = 0;
  66         int total_free = 0;
  67         int offset = 0;
  68         int size = le32_to_cpu(sb->u.qnx4_sb.BitMap->di_size);
  69         struct buffer_head *bh;
  70
  71         while (total < size) {
  72                 if ((bh = bread(sb->s_dev, start + offset, QNX4_BLOCK_SIZE)) == NULL) {
  73                         printk("qnx4: I/O error in counting free blocks\n");
  74                         break;
  75                 }
  76                 count_bits(bh->b_data, size - total, &total_free);
  77                 brelse(bh);
  78                 total += QNX4_BLOCK_SIZE;
  79                 offset++;
  80         }
  81
  82         return total_free;
  83 }
  84
  85 #ifdef CONFIG_QNX4FS_RW
  86
  87 int qnx4_is_free(struct super_block *sb, long block)
  88 {
  89         int start = le32_to_cpu(sb->u.qnx4_sb.BitMap->di_first_xtnt.xtnt_blk) - 1;
  90         int size = le32_to_cpu(sb->u.qnx4_sb.BitMap->di_size);
  91         struct buffer_head *bh;
  92         const char *g;
  93         int ret = -EIO;
  94
  95         start += block / (QNX4_BLOCK_SIZE * 8);
  96         QNX4DEBUG(("qnx4: is_free requesting block [%lu], bitmap in block [%lu]\n",
  97                    (unsigned long) block, (unsigned long) start));
  98         (void) size;            /* CHECKME */
  99         bh = bread(sb->s_dev, start, QNX4_BLOCK_SIZE);
 100         if (bh == NULL) {
 101                 return -EIO;
 102         }
 103         g = bh->b_data + (block % QNX4_BLOCK_SIZE);
 104         if (((*g) & (1 << (block % 8))) == 0) {
 105                 QNX4DEBUG(("qnx4: is_free -> block is free\n"));
 106                 ret = 1;
 107         } else {
 108                 QNX4DEBUG(("qnx4: is_free -> block is busy\n"));
 109                 ret = 0;
 110         }
 111         brelse(bh);
 112
 113         return ret;
 114 }
 115
 116 int qnx4_set_bitmap(struct super_block *sb, long block, int busy)
 117 {
 118         int start = le32_to_cpu(sb->u.qnx4_sb.BitMap->di_first_xtnt.xtnt_blk) - 1;
 119         int size = le32_to_cpu(sb->u.qnx4_sb.BitMap->di_size);
 120         struct buffer_head *bh;
 121         char *g;
 122
 123         start += block / (QNX4_BLOCK_SIZE * 8);
 124         QNX4DEBUG(("qnx4: set_bitmap requesting block [%lu], bitmap in block [%lu]\n",
 125                    (unsigned long) block, (unsigned long) start));
 126         (void) size;            /* CHECKME */
 127         bh = bread(sb->s_dev, start, QNX4_BLOCK_SIZE);
 128         if (bh == NULL) {
 129                 return -EIO;
 130         }
 131         g = bh->b_data + (block % QNX4_BLOCK_SIZE);
 132         if (busy == 0) {
 133                 (*g) &= ~(1 << (block % 8));
 134         } else {
 135                 (*g) |= (1 << (block % 8));
 136         }
 137         mark_buffer_dirty(bh, 1);
 138         brelse(bh);
 139
 140         return 0;
 141 }
 142
 143 static void qnx4_clear_inode(struct inode *inode)
 144 {
 145         struct qnx4_inode_info *qnx4_ino = &inode->u.qnx4_i;
 146
 147         memset(qnx4_ino->i_reserved, 0, sizeof qnx4_ino->i_reserved);
 148         qnx4_ino->i_size = 0;
 149         qnx4_ino->i_num_xtnts = 0;
 150         qnx4_ino->i_mode = 0;
 151         qnx4_ino->i_status = 0;
 152 }
 153
 154 void qnx4_free_inode(struct inode *inode)
 155 {
 156         if (inode->i_ino < 1) {
 157                 printk("free_inode: inode 0 or nonexistent inode\n");
 158                 return;
 159         }
 160         qnx4_clear_inode(inode);
 161         clear_inode(inode);
 162 }
 163
 164 #endif