On Mon, Mar 02, 2020 at 01:47:56PM -0500, Josef Bacik wrote: > We previously were relying on root->reloc_root to be cleaned up by the > drop snapshot, or the error handling. However if btrfs_drop_snapshot() > failed it wouldn't drop the ref for the root. Also we sort of depend on > the right thing to happen with moving reloc roots between lists and the > fs root they belong to, which makes it hard to figure out who owns the > reference. > > Fix this by explicitly holding a reference on the reloc root for > roo->reloc_root. This means that we hold two references on reloc roots, > one for whichever reloc_roots list it's attached to, and the > root->reloc_root we're on. > > This makes it easier to reason out who owns a reference on the root, and > when it needs to be dropped. I think the functions that add a reference should say that in it's comment, so it can be easily pairred with btrfs_put_root. Otherwise yes the explicit references make it easier to see the owner.
