Repair was falling back to non-repair behaviour if it thought the roots
were ok. Now if --repair is specified the same dumping code is always
executed.
metadata_emitter is actually a visitor that passes on it's data
to an encapsulated emitter object.
metadata_emitter -> metadata_emit_visitor
metadata_tree_emitter -> metadata_tree_emit_visitor
The first pass of the repair process scans all metadata working out the
largest orphan btrees. This scan doesn't use as much validation as
the btree_walk function which subsequently gets called.
This patch catches any exceptions thrown by the btree walk function
and removes that btree from consideration.
We've had a trickle of users who accidentally activate the same pool on a
VM and host at the same time. Typically the host doesn't do any IO, but
the kernel will still rewrite the superblock on shutdown. This leaves
the superblock pointing to very out of date btree roots and so we get
massive metadata loss.
This patch changes thin_repair, and thin_dump --repair. They now hunt
for the most recent, undamaged and consistent roots of the device and
mapping trees, and use that as the starting point of the repair.
1. fix the damage type for single_mapping_tree_damage_visitor
2. walk_mapping_tree() now requires the device id
3. update metadata_dumper and thin_ls for the new walk_mapping_tree()
We had a cycle from transaction_manager <-> space_map, and also from
the ref_counters back up to the tm.
This prevented objects being destroyed when various programs exited.
From now on we'll try and only use a shared ptr if ownership is
implied. Otherwise a reference will be used (eg, for up pointers).
