bcache: Fix moving_gc deadlocking with a foreground write
Deadlock happened because a foreground write slept, waiting for a bucket
to be allocated. Normally the gc would mark buckets available for invalidation.
But the moving_gc was stuck waiting for outstanding writes to complete.
These writes used the bcache_wq, the same queue foreground writes used.
This fix gives moving_gc its own work queue, so it was still finish moving
even if foreground writes are stuck waiting for allocation. It also makes
work queue a parameter to the data_insert path, so moving_gc can use its
workqueue for writes.
Signed-off-by: Nicholas Swenson <nks@daterainc.com>
Signed-off-by: Kent Overstreet <kmo@daterainc.com>
diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index a4c7306..6d814f4 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -628,6 +628,8 @@
/* Number of moving GC bios in flight */
struct semaphore moving_in_flight;
+ struct workqueue_struct *moving_gc_wq;
+
struct btree *root;
#ifdef CONFIG_BCACHE_DEBUG