It used to be necessary for the allocator thread to batch up
invalidating buckets when possible - but since we added the btree key
cache that hasn't been a concern, and now it's causing the allocator
thread to livelock when the filesystem is nearly full.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>