Commit 29ebf465 authored Jul 11, 2013 by Kent Overstreet

bcache: Fix GC_SECTORS_USED() calculation

Part of the job of garbage collection is to add up however many sectors
of live data it finds in each bucket, but that doesn't work very well if
it doesn't reset GC_SECTORS_USED() when it starts. Whoops.

This wouldn't have broken anything horribly, but allocation tries to
preferentially reclaim buckets that are mostly empty and that's not
gonna work with an incorrect GC_SECTORS_USED() value.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: linux-stable <stable@vger.kernel.org> # >= v3.10

parent faa56736

drivers/md/bcache/btree.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -1410,8 +1410,10 @@ static void btree_gc_start(struct cache_set *c)
		for_each_cache(ca, c, i)
		for_each_bucket(b, ca) {
		b->gc_gen = b->gen;
		if (!atomic_read(&b->pin))
		if (!atomic_read(&b->pin)) {
		SET_GC_MARK(b, GC_MARK_RECLAIMABLE);
		SET_GC_SECTORS_USED(b, 0);
		}
		}

		mutex_unlock(&c->bucket_lock);