Btrfs: Change the super to point to a tree of trees to enable persistent snapshots

[linux-2.6-block.git] / fs / btrfs / mkfs.c

diff --git a/fs/btrfs/mkfs.c b/fs/btrfs/mkfs.c
index fc1923320de34a0ba541e642b2b740c18a28a55b..dd14ed4fea6c35f6f2077377674415cff5d0d916 100644 (file)
--- a/fs/btrfs/mkfs.c
+++ b/fs/btrfs/mkfs.c
@@ -10,6 +10,120 @@
 #include "ctree.h"
 #include "disk-io.h"
 
+int mkfs(int fd, u64 num_blocks, u16 blocksize)
+{
+       struct btrfs_super_block super;
+       struct btrfs_leaf empty_leaf;
+       struct btrfs_root_item root_item;
+       struct btrfs_item item;
+       struct btrfs_extent_item extent_item;
+       char *block;
+       int ret;
+       u16 itemoff;
+
+       btrfs_set_super_blocknr(&super, 16);
+       btrfs_set_super_root(&super, 17);
+       strcpy((char *)(&super.magic), BTRFS_MAGIC);
+       btrfs_set_super_blocksize(&super, blocksize);
+       btrfs_set_super_total_blocks(&super, num_blocks);
+       btrfs_set_super_blocks_used(&super, 0);
+
+       block = malloc(blocksize);
+       memset(block, 0, blocksize);
+       BUG_ON(sizeof(super) > blocksize);
+       memcpy(block, &super, sizeof(super));
+       ret = pwrite(fd, block, blocksize, BTRFS_SUPER_INFO_OFFSET(blocksize));
+       BUG_ON(ret != blocksize);
+
+       /* create the tree of root objects */
+       memset(&empty_leaf, 0, sizeof(empty_leaf));
+       btrfs_set_header_parentid(&empty_leaf.header, BTRFS_ROOT_TREE_OBJECTID);
+       btrfs_set_header_blocknr(&empty_leaf.header, 17);
+       btrfs_set_header_nritems(&empty_leaf.header, 2);
+
+       /* create the items for the root tree */
+       btrfs_set_root_blocknr(&root_item, 18);
+       btrfs_set_root_refs(&root_item, 1);
+       itemoff = LEAF_DATA_SIZE - sizeof(root_item);
+       btrfs_set_item_offset(&item, itemoff);
+       btrfs_set_item_size(&item, sizeof(root_item));
+       btrfs_set_key_objectid(&item.key, BTRFS_EXTENT_TREE_OBJECTID);
+       btrfs_set_key_offset(&item.key, 0);
+       btrfs_set_key_flags(&item.key, 0);
+       memcpy(empty_leaf.items, &item, sizeof(item));
+       memcpy(empty_leaf.data + itemoff, &root_item, sizeof(root_item));
+
+       btrfs_set_root_blocknr(&root_item, 19);
+       itemoff = itemoff - sizeof(root_item);
+       btrfs_set_item_offset(&item, itemoff);
+       btrfs_set_key_objectid(&item.key, BTRFS_FS_TREE_OBJECTID);
+       memcpy(empty_leaf.items + 1, &item, sizeof(item));
+       memcpy(empty_leaf.data + itemoff, &root_item, sizeof(root_item));
+       ret = pwrite(fd, &empty_leaf, blocksize, 17 * blocksize);
+
+       /* create the items for the extent tree */
+       btrfs_set_header_parentid(&empty_leaf.header,
+                                 BTRFS_EXTENT_TREE_OBJECTID);
+       btrfs_set_header_blocknr(&empty_leaf.header, 18);
+       btrfs_set_header_nritems(&empty_leaf.header, 4);
+
+       /* item1, reserve blocks 0-16 */
+       btrfs_set_key_objectid(&item.key, 0);
+       btrfs_set_key_offset(&item.key, 17);
+       btrfs_set_key_flags(&item.key, 0);
+       itemoff = LEAF_DATA_SIZE - sizeof(struct btrfs_extent_item);
+       btrfs_set_item_offset(&item, itemoff);
+       btrfs_set_item_size(&item, sizeof(struct btrfs_extent_item));
+       btrfs_set_extent_refs(&extent_item, 1);
+       btrfs_set_extent_owner(&extent_item, 0);
+       memcpy(empty_leaf.items, &item, sizeof(item));
+       memcpy(empty_leaf.data + btrfs_item_offset(&item), &extent_item,
+               btrfs_item_size(&item));
+
+       /* item2, give block 17 to the root */
+       btrfs_set_key_objectid(&item.key, 17);
+       btrfs_set_key_offset(&item.key, 1);
+       itemoff = itemoff - sizeof(struct btrfs_extent_item);
+       btrfs_set_item_offset(&item, itemoff);
+       btrfs_set_extent_owner(&extent_item, BTRFS_ROOT_TREE_OBJECTID);
+       memcpy(empty_leaf.items + 1, &item, sizeof(item));
+       memcpy(empty_leaf.data + btrfs_item_offset(&item), &extent_item,
+               btrfs_item_size(&item));
+
+       /* item3, give block 18 to the extent root */
+       btrfs_set_key_objectid(&item.key, 18);
+       btrfs_set_key_offset(&item.key, 1);
+       itemoff = itemoff - sizeof(struct btrfs_extent_item);
+       btrfs_set_item_offset(&item, itemoff);
+       btrfs_set_extent_owner(&extent_item, BTRFS_EXTENT_TREE_OBJECTID);
+       memcpy(empty_leaf.items + 2, &item, sizeof(item));
+       memcpy(empty_leaf.data + btrfs_item_offset(&item), &extent_item,
+               btrfs_item_size(&item));
+
+       /* item4, give block 19 to the FS root */
+       btrfs_set_key_objectid(&item.key, 19);
+       btrfs_set_key_offset(&item.key, 1);
+       itemoff = itemoff - sizeof(struct btrfs_extent_item);
+       btrfs_set_item_offset(&item, itemoff);
+       btrfs_set_extent_owner(&extent_item, BTRFS_FS_TREE_OBJECTID);
+       memcpy(empty_leaf.items + 3, &item, sizeof(item));
+       memcpy(empty_leaf.data + btrfs_item_offset(&item), &extent_item,
+               btrfs_item_size(&item));
+       ret = pwrite(fd, &empty_leaf, blocksize, 18 * blocksize);
+       if (ret != sizeof(empty_leaf))
+               return -1;
+
+       /* finally create the FS root */
+       btrfs_set_header_parentid(&empty_leaf.header, BTRFS_FS_TREE_OBJECTID);
+       btrfs_set_header_blocknr(&empty_leaf.header, 19);
+       btrfs_set_header_nritems(&empty_leaf.header, 0);
+       ret = pwrite(fd, &empty_leaf, blocksize, 19 * blocksize);
+       if (ret != sizeof(empty_leaf))
+               return -1;
+       return 0;
+}
+
+#if 0
 int mkfs(int fd)
 {
        struct btrfs_root_info info[2];
@@ -20,13 +134,14 @@ int mkfs(int fd)
 
        /* setup the super block area */
        memset(info, 0, sizeof(info));
-       info[0].blocknr = 16;
-       info[0].objectid = 1;
-       info[0].tree_root = 17;
+       btrfs_set_root_blocknr(info, 16);
+       btrfs_set_root_objectid(info, 1);
+       btrfs_set_root_tree_root(info, 17);
+
+       btrfs_set_root_blocknr(info + 1, 16);
+       btrfs_set_root_objectid(info + 1, 2);
+       btrfs_set_root_tree_root(info + 1, 18);
 
-       info[1].blocknr = 16;
-       info[1].objectid = 2;
-       info[1].tree_root = 18;
        ret = pwrite(fd, info, sizeof(info),
                     BTRFS_SUPER_INFO_OFFSET(BTRFS_BLOCKSIZE));
        if (ret != sizeof(info))
@@ -81,3 +196,4 @@ int mkfs(int fd)
                return -1;
        return 0;
 }
+#endif