*
* The superblock signature is not valid, denotes a partially created
* filesystem, needs to be finalized.
+ *
+ * The temporary fs will have the following chunk layout:
+ * Device extent:
+ * 0 1M 5M ......
+ * | Reserved | dev extent for SYS chunk |
+ *
+ * And chunk mapping will be:
+ * Chunk mapping:
+ * 0 1M 5M
+ * | | System chunk, 1:1 mapped |
+ *
+ * That's to say, there will only be *ONE* system chunk, mapped to
+ * [1M, 5M) physical offset.
+ * And the only chunk is also in logical address [1M, 5M), containing
+ * all essential tree blocks.
*/
int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
{
cfg->blocks[MKFS_SUPER_BLOCK] = BTRFS_SUPER_INFO_OFFSET;
for (i = 1; i < MKFS_BLOCK_COUNT; i++) {
- cfg->blocks[i] = BTRFS_SUPER_INFO_OFFSET + SZ_1M +
- cfg->nodesize * i;
+ cfg->blocks[i] = BTRFS_BLOCK_RESERVED_1M_FOR_SUPER +
+ cfg->nodesize * (i - 1);
}
btrfs_set_super_bytenr(&super, cfg->blocks[MKFS_SUPER_BLOCK]);
/* then we have chunk 0 */
btrfs_set_disk_key_objectid(&disk_key, BTRFS_FIRST_CHUNK_TREE_OBJECTID);
- btrfs_set_disk_key_offset(&disk_key, 0);
+ btrfs_set_disk_key_offset(&disk_key, BTRFS_BLOCK_RESERVED_1M_FOR_SUPER);
btrfs_set_disk_key_type(&disk_key, BTRFS_CHUNK_ITEM_KEY);
btrfs_set_item_key(buf, &disk_key, nritems);
btrfs_set_item_offset(buf, btrfs_item_nr(nritems), itemoff);
btrfs_set_chunk_sector_size(buf, chunk, cfg->sectorsize);
btrfs_set_chunk_num_stripes(buf, chunk, 1);
btrfs_set_stripe_devid_nr(buf, chunk, 0, 1);
- btrfs_set_stripe_offset_nr(buf, chunk, 0, 0);
+ btrfs_set_stripe_offset_nr(buf, chunk, 0,
+ BTRFS_BLOCK_RESERVED_1M_FOR_SUPER);
nritems++;
write_extent_buffer(buf, super.dev_item.uuid,
sizeof(struct btrfs_dev_extent);
btrfs_set_disk_key_objectid(&disk_key, 1);
- btrfs_set_disk_key_offset(&disk_key, 0);
+ btrfs_set_disk_key_offset(&disk_key, BTRFS_BLOCK_RESERVED_1M_FOR_SUPER);
btrfs_set_disk_key_type(&disk_key, BTRFS_DEV_EXTENT_KEY);
btrfs_set_item_key(buf, &disk_key, nritems);
btrfs_set_item_offset(buf, btrfs_item_nr(nritems), itemoff);
BTRFS_CHUNK_TREE_OBJECTID);
btrfs_set_dev_extent_chunk_objectid(buf, dev_extent,
BTRFS_FIRST_CHUNK_TREE_OBJECTID);
- btrfs_set_dev_extent_chunk_offset(buf, dev_extent, 0);
+ btrfs_set_dev_extent_chunk_offset(buf, dev_extent,
+ BTRFS_BLOCK_RESERVED_1M_FOR_SUPER);
write_extent_buffer(buf, chunk_tree_uuid,
(unsigned long)btrfs_dev_extent_chunk_tree_uuid(dev_extent),
/*
* Minimal size calculation is complex due to several factors:
+ * 0) Reserved 1M range.
+ *
* 1) Temporary chunk reuse
* If specified chunk profile is SINGLE, we can reuse
* temporary chunks, no need to allocate new chunks.
* The latter two are all 8M, accroding to @calc_size of
* btrfs_alloc_chunk().
*/
- reserved += BTRFS_MKFS_SYSTEM_GROUP_SIZE + SZ_8M * 2;
+ reserved += BTRFS_BLOCK_RESERVED_1M_FOR_SUPER +
+ BTRFS_MKFS_SYSTEM_GROUP_SIZE + SZ_8M * 2;
/*
* For real chunks, we need to select different sizes: