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/time.h>
  18 #include <linux/fs.h>
  19 #include <linux/qnx4_fs.h>
  20 #include <linux/stat.h>
  21 #include <linux/kernel.h>
  22 #include <linux/string.h>
  23 #include <linux/buffer_head.h>
  24 #include <linux/bitops.h>
  25
  26 #if 0
  27 int qnx4_new_block(struct super_block *sb)
  28 {
  29         return 0;
  30 }
  31 #endif  /*  0  */
  32
  33 static void count_bits(register const char *bmPart, register int size,
  34                        int *const tf)
  35 {
  36         char b;
  37         int tot = *tf;
  38
  39         if (size > QNX4_BLOCK_SIZE) {
  40                 size = QNX4_BLOCK_SIZE;
  41         }
  42         do {
  43                 b = *bmPart++;
  44                 if ((b & 1) == 0)
  45                         tot++;
  46                 if ((b & 2) == 0)
  47                         tot++;
  48                 if ((b & 4) == 0)
  49                         tot++;
  50                 if ((b & 8) == 0)
  51                         tot++;
  52                 if ((b & 16) == 0)
  53                         tot++;
  54                 if ((b & 32) == 0)
  55                         tot++;
  56                 if ((b & 64) == 0)
  57                         tot++;
  58                 if ((b & 128) == 0)
  59                         tot++;
  60                 size--;
  61         } while (size != 0);
  62         *tf = tot;
  63 }
  64
  65 unsigned long qnx4_count_free_blocks(struct super_block *sb)
  66 {
  67         int start = le32_to_cpu(qnx4_sb(sb)->BitMap->di_first_xtnt.xtnt_blk) - 1;
  68         int total = 0;
  69         int total_free = 0;
  70         int offset = 0;
  71         int size = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size);
  72         struct buffer_head *bh;
  73
  74         while (total < size) {
  75                 if ((bh = sb_bread(sb, start + offset)) == NULL) {
  76                         printk("qnx4: I/O error in counting free blocks\n");
  77                         break;
  78                 }
  79                 count_bits(bh->b_data, size - total, &total_free);
  80                 brelse(bh);
  81                 total += QNX4_BLOCK_SIZE;
  82                 offset++;
  83         }
  84
  85         return total_free;
  86 }
  87
  88 #ifdef CONFIG_QNX4FS_RW
  89
  90 int qnx4_is_free(struct super_block *sb, long block)
  91 {
  92         int start = le32_to_cpu(qnx4_sb(sb)->BitMap->di_first_xtnt.xtnt_blk) - 1;
  93         int size = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size);
  94         struct buffer_head *bh;
  95         const char *g;
  96         int ret = -EIO;
  97
  98         start += block / (QNX4_BLOCK_SIZE * 8);
  99         QNX4DEBUG(("qnx4: is_free requesting block [%lu], bitmap in block [%lu]\n",
 100                    (unsigned long) block, (unsigned long) start));
 101         (void) size;            /* CHECKME */
 102         bh = sb_bread(sb, start);
 103         if (bh == NULL) {
 104                 return -EIO;
 105         }
 106         g = bh->b_data + (block % QNX4_BLOCK_SIZE);
 107         if (((*g) & (1 << (block % 8))) == 0) {
 108                 QNX4DEBUG(("qnx4: is_free -> block is free\n"));
 109                 ret = 1;
 110         } else {
 111                 QNX4DEBUG(("qnx4: is_free -> block is busy\n"));
 112                 ret = 0;
 113         }
 114         brelse(bh);
 115
 116         return ret;
 117 }
 118
 119 int qnx4_set_bitmap(struct super_block *sb, long block, int busy)
 120 {
 121         int start = le32_to_cpu(qnx4_sb(sb)->BitMap->di_first_xtnt.xtnt_blk) - 1;
 122         int size = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size);
 123         struct buffer_head *bh;
 124         char *g;
 125
 126         start += block / (QNX4_BLOCK_SIZE * 8);
 127         QNX4DEBUG(("qnx4: set_bitmap requesting block [%lu], bitmap in block [%lu]\n",
 128                    (unsigned long) block, (unsigned long) start));
 129         (void) size;            /* CHECKME */
 130         bh = sb_bread(sb, start);
 131         if (bh == NULL) {
 132                 return -EIO;
 133         }
 134         g = bh->b_data + (block % QNX4_BLOCK_SIZE);
 135         if (busy == 0) {
 136                 (*g) &= ~(1 << (block % 8));
 137         } else {
 138                 (*g) |= (1 << (block % 8));
 139         }
 140         mark_buffer_dirty(bh);
 141         brelse(bh);
 142
 143         return 0;
 144 }
 145
 146 static void qnx4_clear_inode(struct inode *inode)
 147 {
 148         struct qnx4_inode_entry *qnx4_ino = qnx4_raw_inode(inode);
 149         /* What for? */
 150         memset(qnx4_ino->di_fname, 0, sizeof qnx4_ino->di_fname);
 151         qnx4_ino->di_size = 0;
 152         qnx4_ino->di_num_xtnts = 0;
 153         qnx4_ino->di_mode = 0;
 154         qnx4_ino->di_status = 0;
 155 }
 156
 157 void qnx4_free_inode(struct inode *inode)
 158 {
 159         if (inode->i_ino < 1) {
 160                 printk("free_inode: inode 0 or nonexistent inode\n");
 161                 return;
 162         }
 163         qnx4_clear_inode(inode);
 164         clear_inode(inode);
 165 }
 166
 167 #endif