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