btrfs: track owning root in btrfs_ref

While data extents require us to store additional inline refs to track
the original owner on free, this information is available implicitly for
metadata. It is found in the owner field of the header of the tree
block. Even if other trees refer to this block and the original ref goes
away, we will not rewrite that header field, so it will reliably give the
original owner.

In addition, there is a relocation case where a new data extent needs to
have an owning root separate from the referring root wired through
delayed refs.

To use it for recording simple quota deltas, we need to wire this root
id through from when we create the delayed ref until we fully process
it. Store it in the generic btrfs_ref struct of the delayed ref.

Signed-off-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 13 insertions, 8 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 52efc8e44cdb..2dda3ecb49e6 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2452,7 +2452,7 @@ static int __btrfs_mod_ref(struct btrfs_trans_handle *trans,
 			num_bytes = btrfs_file_extent_disk_num_bytes(buf, fi);
 			key.offset -= btrfs_file_extent_offset(buf, fi);
 			btrfs_init_generic_ref(&generic_ref, action, bytenr,
-					       num_bytes, parent);
+					       num_bytes, parent, ref_root);
 			btrfs_init_data_ref(&generic_ref, ref_root, key.objectid,
 					    key.offset, root->root_key.objectid,
 					    for_reloc);
@@ -2465,8 +2465,9 @@ static int __btrfs_mod_ref(struct btrfs_trans_handle *trans,
 		} else {
 			bytenr = btrfs_node_blockptr(buf, i);
 			num_bytes = fs_info->nodesize;
+			/* We don't know the owning_root, use 0. */
 			btrfs_init_generic_ref(&generic_ref, action, bytenr,
-					       num_bytes, parent);
+					       num_bytes, parent, 0);
 			btrfs_init_tree_ref(&generic_ref, level - 1, ref_root,
 					    root->root_key.objectid, for_reloc);
 			if (inc)
@@ -3289,7 +3290,7 @@ void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
 	int ret;
 
 	btrfs_init_generic_ref(&generic_ref, BTRFS_DROP_DELAYED_REF,
-			       buf->start, buf->len, parent);
+			       buf->start, buf->len, parent, btrfs_header_owner(buf));
 	btrfs_init_tree_ref(&generic_ref, btrfs_header_level(buf),
 			    root_id, 0, false);
 
@@ -4751,12 +4752,14 @@ int btrfs_alloc_reserved_file_extent(struct btrfs_trans_handle *trans,
 				     struct btrfs_key *ins)
 {
 	struct btrfs_ref generic_ref = { 0 };
+	u64 root_objectid = root->root_key.objectid;
+	u64 owning_root = root_objectid;
 
-	BUG_ON(root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
+	BUG_ON(root_objectid == BTRFS_TREE_LOG_OBJECTID);
 
 	btrfs_init_generic_ref(&generic_ref, BTRFS_ADD_DELAYED_EXTENT,
-			       ins->objectid, ins->offset, 0);
-	btrfs_init_data_ref(&generic_ref, root->root_key.objectid, owner,
+			       ins->objectid, ins->offset, 0, owning_root);
+	btrfs_init_data_ref(&generic_ref, root_objectid, owner,
 			    offset, 0, false);
 	btrfs_ref_tree_mod(root->fs_info, &generic_ref);
 
@@ -4982,7 +4985,8 @@ struct extent_buffer *btrfs_alloc_tree_block(struct btrfs_trans_handle *trans,
 		extent_op->level = level;
 
 		btrfs_init_generic_ref(&generic_ref, BTRFS_ADD_DELAYED_EXTENT,
-				       ins.objectid, ins.offset, parent);
+				       ins.objectid, ins.offset, parent,
+				       btrfs_header_owner(buf));
 		btrfs_init_tree_ref(&generic_ref, level, root_objectid,
 				    root->root_key.objectid, false);
 		btrfs_ref_tree_mod(fs_info, &generic_ref);
@@ -5403,7 +5407,8 @@ skip:
 		find_next_key(path, level, &wc->drop_progress);
 
 		btrfs_init_generic_ref(&ref, BTRFS_DROP_DELAYED_REF, bytenr,
-				       fs_info->nodesize, parent);
+				       fs_info->nodesize, parent,
+				       btrfs_header_owner(next));
 		btrfs_init_tree_ref(&ref, level - 1, root->root_key.objectid,
 				    0, false);
 		ret = btrfs_free_extent(trans, &ref);