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>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/md/bcache/request.h b/drivers/md/bcache/request.h
index 39f21dbedc38..c117c4082aa2 100644
--- a/drivers/md/bcache/request.h
+++ b/drivers/md/bcache/request.h
@@ -7,6 +7,7 @@ struct data_insert_op {
 	struct closure		cl;
 	struct cache_set	*c;
 	struct bio		*bio;
+	struct workqueue_struct *wq;
 
 	unsigned		inode;
 	uint16_t		write_point;