mkfs.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 int mkfs(int fd, u64 num_blocks, u32 blocksize)
  14 {
  15         struct btrfs_super_block super;
  16         struct btrfs_leaf *empty_leaf;
  17         struct btrfs_root_item root_item;
  18         struct btrfs_item item;
  19         struct btrfs_extent_item extent_item;
  20         char *block;
  21         int ret;
  22         u32 itemoff;
  23         u32 start_block = BTRFS_SUPER_INFO_OFFSET / blocksize;
  24
  25         btrfs_set_super_blocknr(&super, start_block);
  26         btrfs_set_super_root(&super, start_block + 1);
  27         strcpy((char *)(&super.magic), BTRFS_MAGIC);
  28         btrfs_set_super_blocksize(&super, blocksize);
  29         btrfs_set_super_total_blocks(&super, num_blocks);
  30         btrfs_set_super_blocks_used(&super, 0);
  31
  32         block = malloc(blocksize);
  33         memset(block, 0, blocksize);
  34         BUG_ON(sizeof(super) > blocksize);
  35         memcpy(block, &super, sizeof(super));
  36         ret = pwrite(fd, block, blocksize, BTRFS_SUPER_INFO_OFFSET);
  37         BUG_ON(ret != blocksize);
  38
  39         /* create the tree of root objects */
  40         empty_leaf = malloc(blocksize);
  41         memset(empty_leaf, 0, blocksize);
  42         btrfs_set_header_parentid(&empty_leaf->header,
  43                                   BTRFS_ROOT_TREE_OBJECTID);
  44         btrfs_set_header_blocknr(&empty_leaf->header, start_block + 1);
  45         btrfs_set_header_nritems(&empty_leaf->header, 2);
  46
  47         /* create the items for the root tree */
  48         btrfs_set_root_blocknr(&root_item, start_block + 2);
  49         btrfs_set_root_refs(&root_item, 1);
  50         itemoff = __BTRFS_LEAF_DATA_SIZE(blocksize) - sizeof(root_item);
  51         btrfs_set_item_offset(&item, itemoff);
  52         btrfs_set_item_size(&item, sizeof(root_item));
  53         btrfs_set_key_objectid(&item.key, BTRFS_EXTENT_TREE_OBJECTID);
  54         btrfs_set_key_offset(&item.key, 0);
  55         btrfs_set_key_flags(&item.key, 0);
  56         memcpy(empty_leaf->items, &item, sizeof(item));
  57         memcpy(btrfs_leaf_data(empty_leaf) + itemoff,
  58                 &root_item, sizeof(root_item));
  59
  60         btrfs_set_root_blocknr(&root_item, start_block + 3);
  61         itemoff = itemoff - sizeof(root_item);
  62         btrfs_set_item_offset(&item, itemoff);
  63         btrfs_set_key_objectid(&item.key, BTRFS_FS_TREE_OBJECTID);
  64         memcpy(empty_leaf->items + 1, &item, sizeof(item));
  65         memcpy(btrfs_leaf_data(empty_leaf) + itemoff,
  66                 &root_item, sizeof(root_item));
  67         ret = pwrite(fd, empty_leaf, blocksize, (start_block + 1) * blocksize);
  68
  69         /* create the items for the extent tree */
  70         btrfs_set_header_parentid(&empty_leaf->header,
  71                                   BTRFS_EXTENT_TREE_OBJECTID);
  72         btrfs_set_header_blocknr(&empty_leaf->header, start_block + 2);
  73         btrfs_set_header_nritems(&empty_leaf->header, 4);
  74
  75         /* item1, reserve blocks 0-16 */
  76         btrfs_set_key_objectid(&item.key, 0);
  77         btrfs_set_key_offset(&item.key, start_block + 1);
  78         btrfs_set_key_flags(&item.key, 0);
  79         itemoff = __BTRFS_LEAF_DATA_SIZE(blocksize) -
  80                         sizeof(struct btrfs_extent_item);
  81         btrfs_set_item_offset(&item, itemoff);
  82         btrfs_set_item_size(&item, sizeof(struct btrfs_extent_item));
  83         btrfs_set_extent_refs(&extent_item, 1);
  84         btrfs_set_extent_owner(&extent_item, 0);
  85         memcpy(empty_leaf->items, &item, sizeof(item));
  86         memcpy(btrfs_leaf_data(empty_leaf) + btrfs_item_offset(&item),
  87                 &extent_item, btrfs_item_size(&item));
  88
  89         /* item2, give block 17 to the root */
  90         btrfs_set_key_objectid(&item.key, start_block + 1);
  91         btrfs_set_key_offset(&item.key, 1);
  92         itemoff = itemoff - sizeof(struct btrfs_extent_item);
  93         btrfs_set_item_offset(&item, itemoff);
  94         btrfs_set_extent_owner(&extent_item, BTRFS_ROOT_TREE_OBJECTID);
  95         memcpy(empty_leaf->items + 1, &item, sizeof(item));
  96         memcpy(btrfs_leaf_data(empty_leaf) + btrfs_item_offset(&item),
  97                 &extent_item, btrfs_item_size(&item));
  98
  99         /* item3, give block 18 to the extent root */
 100         btrfs_set_key_objectid(&item.key, start_block + 2);
 101         btrfs_set_key_offset(&item.key, 1);
 102         itemoff = itemoff - sizeof(struct btrfs_extent_item);
 103         btrfs_set_item_offset(&item, itemoff);
 104         btrfs_set_extent_owner(&extent_item, BTRFS_EXTENT_TREE_OBJECTID);
 105         memcpy(empty_leaf->items + 2, &item, sizeof(item));
 106         memcpy(btrfs_leaf_data(empty_leaf) + btrfs_item_offset(&item),
 107                 &extent_item, btrfs_item_size(&item));
 108
 109         /* item4, give block 19 to the FS root */
 110         btrfs_set_key_objectid(&item.key, start_block + 3);
 111         btrfs_set_key_offset(&item.key, 1);
 112         itemoff = itemoff - sizeof(struct btrfs_extent_item);
 113         btrfs_set_item_offset(&item, itemoff);
 114         btrfs_set_extent_owner(&extent_item, BTRFS_FS_TREE_OBJECTID);
 115         memcpy(empty_leaf->items + 3, &item, sizeof(item));
 116         memcpy(btrfs_leaf_data(empty_leaf) + btrfs_item_offset(&item),
 117                 &extent_item, btrfs_item_size(&item));
 118         ret = pwrite(fd, empty_leaf, blocksize, (start_block + 2) * blocksize);
 119         if (ret != blocksize)
 120                 return -1;
 121
 122         /* finally create the FS root */
 123         btrfs_set_header_parentid(&empty_leaf->header, BTRFS_FS_TREE_OBJECTID);
 124         btrfs_set_header_blocknr(&empty_leaf->header, start_block + 3);
 125         btrfs_set_header_nritems(&empty_leaf->header, 0);
 126         ret = pwrite(fd, empty_leaf, blocksize, (start_block + 3) * blocksize);
 127         if (ret != blocksize)
 128                 return -1;
 129         return 0;
 130 }