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