bcachefs: Fragmentation LRU

Now that we have much more efficient updates to the LRU btree, this
patch adds a new LRU that indexes buckets by fragmentation.

This means copygc no longer has to scan every bucket to find buckets
that need to be evacuated.

Changes:
 - A new field in bch_alloc_v4, fragmentation_lru - this corresponds to
   the bucket's position in the fragmentation LRU. We add a new field
   for this instead of calculating it as needed because we may make the
   fragmentation LRU optional; this field indicates whether a bucket is
   on the fragmentation LRU.

   Also, zoned devices will introduce variable bucket sizes; explicitly
   recording the LRU position will be safer for them.

 - A new copygc path for using the fragmentation LRU instead of
   scanning every bucket and building up an in-memory heap.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

1 files changed, 0 insertions, 1 deletions

diff --git a/fs/bcachefs/super.c b/fs/bcachefs/super.c
index 58517f6d128f..f703e41c7560 100644
--- a/fs/bcachefs/super.c
+++ b/fs/bcachefs/super.c
@@ -487,7 +487,6 @@ static void __bch2_fs_free(struct bch_fs *c)
 	kfree(rcu_dereference_protected(c->disk_groups, 1));
 	kfree(c->journal_seq_blacklist_table);
 	kfree(c->unused_inode_hints);
-	free_heap(&c->copygc_heap);
 
 	if (c->io_complete_wq)
 		destroy_workqueue(c->io_complete_wq);