Btrfs: Add chunk uuids and update multi-device back references

Block headers now store the chunk tree uuid

Chunk items records the device uuid for each stripes

Device extent items record better back refs to the chunk tree

Block groups record better back refs to the chunk tree

The chunk tree format has also changed.  The objectid of BTRFS_CHUNK_ITEM_KEY
used to be the logical offset of the chunk.  Now it is a chunk tree id,
with the logical offset being stored in the offset field of the key.

This allows a single chunk tree to record multiple logical address spaces,
upping the number of bytes indexed by a chunk tree from 2^64 to
2^128.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 9c94dddde704..79c284c87286 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1125,6 +1125,10 @@ struct btrfs_root *open_ctree(struct super_block *sb,
                                            blocksize);
         BUG_ON(!chunk_root->node);
 
+        read_extent_buffer(chunk_root->node, fs_info->chunk_tree_uuid,
+                 (unsigned long)btrfs_header_chunk_tree_uuid(chunk_root->node),
+                 BTRFS_UUID_SIZE);
+
         ret = btrfs_read_chunk_tree(chunk_root);
         BUG_ON(ret);
 
@@ -1229,7 +1233,7 @@ int write_all_supers(struct btrfs_root *root)
                 btrfs_set_device_sector_size(sb, dev_item, dev->sector_size);
                 write_extent_buffer(sb, dev->uuid,
                                     (unsigned long)btrfs_device_uuid(dev_item),
-                                    BTRFS_DEV_UUID_SIZE);
+                                    BTRFS_UUID_SIZE);
 
                 btrfs_set_header_flag(sb, BTRFS_HEADER_FLAG_WRITTEN);
                 csum_tree_block(root, sb, 0);