bcache: Rework allocator reserves

We need a reserve for allocating buckets for new btree nodes - and now that
we've got multiple btrees, it really needs to be per btree.

This reworks the reserves so we've got separate freelists for each reserve
instead of watermarks, which seems to make things a bit cleaner, and it adds
some code so that btree_split() can make sure the reserve is available before it
starts.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/md/bcache/btree.h b/drivers/md/bcache/btree.h
index d68af7442f70..4f0378ac1f7b 100644
--- a/drivers/md/bcache/btree.h
+++ b/drivers/md/bcache/btree.h
@@ -241,6 +241,9 @@ void bkey_put(struct cache_set *c, struct bkey *k);
 /* Recursing down the btree */
 
 struct btree_op {
+	/* for waiting on btree reserve in btree_split() */
+	wait_queue_t		wait;
+
 	/* Btree level at which we start taking write locks */
 	short			lock;
 
@@ -250,6 +253,7 @@ struct btree_op {
 static inline void bch_btree_op_init(struct btree_op *op, int write_lock_level)
 {
 	memset(op, 0, sizeof(struct btree_op));
+	init_wait(&op->wait);
 	op->lock = write_lock_level;
 }