disk-io.c

   1 #define _XOPEN_SOURCE 500
   2 #include <stdio.h>
   3 #include <stdlib.h>
   4 #include <sys/types.h>
   5 #include <sys/stat.h>
   6 #include <fcntl.h>
   7 #include <unistd.h>
   8 #include "kerncompat.h"
   9 #include "radix-tree.h"
  10 #include "ctree.h"
  11 #include "disk-io.h"
  12
  13 static int allocated_blocks = 0;
  14
  15 struct ctree_header {
  16         u64 root_block;
  17 } __attribute__ ((__packed__));
  18
  19 static int get_free_block(struct ctree_root *root, u64 *block)
  20 {
  21         struct stat st;
  22         int ret;
  23
  24         st.st_size = 0;
  25         ret = fstat(root->fp, &st);
  26         if (st.st_size > sizeof(struct ctree_header)) {
  27                 *block = (st.st_size -
  28                         sizeof(struct ctree_header)) / CTREE_BLOCKSIZE;
  29         } else {
  30                 *block = 0;
  31         }
  32         ret = ftruncate(root->fp, sizeof(struct ctree_header) + (*block + 1) *
  33                         CTREE_BLOCKSIZE);
  34         return ret;
  35 }
  36
  37 struct tree_buffer *alloc_tree_block(struct ctree_root *root, u64 blocknr)
  38 {
  39         struct tree_buffer *buf;
  40         int ret;
  41         buf = malloc(sizeof(struct tree_buffer));
  42         if (!buf)
  43                 return buf;
  44         allocated_blocks++;
  45         buf->blocknr = blocknr;
  46         buf->count = 1;
  47         radix_tree_preload(GFP_KERNEL);
  48         ret = radix_tree_insert(&root->cache_radix, blocknr, buf);
  49         radix_tree_preload_end();
  50         if (ret) {
  51                 free(buf);
  52                 return NULL;
  53         }
  54         return buf;
  55 }
  56
  57 struct tree_buffer *alloc_free_block(struct ctree_root *root)
  58 {
  59         u64 free_block;
  60         int ret;
  61         struct tree_buffer * buf;
  62         ret = get_free_block(root, &free_block);
  63         if (ret) {
  64                 BUG();
  65                 return NULL;
  66         }
  67         buf = alloc_tree_block(root, free_block);
  68         if (!buf)
  69                 BUG();
  70         return buf;
  71 }
  72
  73 struct tree_buffer *read_tree_block(struct ctree_root *root, u64 blocknr)
  74 {
  75         loff_t offset = blocknr * CTREE_BLOCKSIZE + sizeof(struct ctree_header);
  76         struct tree_buffer *buf;
  77         int ret;
  78
  79         buf = radix_tree_lookup(&root->cache_radix, blocknr);
  80         if (buf) {
  81                 buf->count++;
  82                 if (buf->blocknr != blocknr)
  83                         BUG();
  84                 if (buf->blocknr != buf->node.header.blocknr)
  85                         BUG();
  86                 return buf;
  87         }
  88         buf = alloc_tree_block(root, blocknr);
  89         if (!buf)
  90                 return NULL;
  91         ret = pread(root->fp, &buf->node, CTREE_BLOCKSIZE, offset);
  92         if (ret != CTREE_BLOCKSIZE) {
  93                 free(buf);
  94                 return NULL;
  95         }
  96         if (buf->blocknr != buf->node.header.blocknr)
  97                 BUG();
  98         return buf;
  99 }
 100
 101 int write_tree_block(struct ctree_root *root, struct tree_buffer *buf)
 102 {
 103         u64 blocknr = buf->blocknr;
 104         loff_t offset = blocknr * CTREE_BLOCKSIZE + sizeof(struct ctree_header);
 105         int ret;
 106
 107         if (buf->blocknr != buf->node.header.blocknr)
 108                 BUG();
 109         ret = pwrite(root->fp, &buf->node, CTREE_BLOCKSIZE, offset);
 110         if (ret != CTREE_BLOCKSIZE)
 111                 return ret;
 112         if (buf == root->node)
 113                 return update_root_block(root);
 114         return 0;
 115 }
 116
 117 struct ctree_root *open_ctree(char *filename)
 118 {
 119         struct ctree_root *root = malloc(sizeof(struct ctree_root));
 120         int fp;
 121         u64 root_block;
 122         int ret;
 123
 124         fp = open(filename, O_CREAT | O_RDWR);
 125         if (fp < 0) {
 126                 free(root);
 127                 return NULL;
 128         }
 129         root->fp = fp;
 130         INIT_RADIX_TREE(&root->cache_radix, GFP_KERNEL);
 131         ret = pread(fp, &root_block, sizeof(u64), 0);
 132         if (ret == sizeof(u64)) {
 133                 printf("reading root node at block %lu\n", root_block);
 134                 root->node = read_tree_block(root, root_block);
 135         } else
 136                 root->node = NULL;
 137         return root;
 138 }
 139
 140 int close_ctree(struct ctree_root *root)
 141 {
 142         close(root->fp);
 143         if (root->node)
 144                 tree_block_release(root, root->node);
 145         free(root);
 146         printf("on close %d blocks are allocated\n", allocated_blocks);
 147         return 0;
 148 }
 149
 150 int update_root_block(struct ctree_root *root)
 151 {
 152         int ret;
 153         u64 root_block = root->node->blocknr;
 154
 155         ret = pwrite(root->fp, &root_block, sizeof(u64), 0);
 156         if (ret != sizeof(u64))
 157                 return ret;
 158         return 0;
 159 }
 160
 161 void tree_block_release(struct ctree_root *root, struct tree_buffer *buf)
 162 {
 163         buf->count--;
 164         if (buf->count == 0) {
 165                 if (!radix_tree_lookup(&root->cache_radix, buf->blocknr))
 166                         BUG();
 167                 radix_tree_delete(&root->cache_radix, buf->blocknr);
 168                 memset(buf, 0, sizeof(*buf));
 169                 free(buf);
 170                 BUG_ON(allocated_blocks == 0);
 171                 allocated_blocks--;
 172         }
 173 }
 174