bcache: A block layer cache

Does writethrough and writeback caching, handles unclean shutdown, and
has a bunch of other nifty features motivated by real world usage.

See the wiki at http://bcache.evilpiepirate.org for more.

Signed-off-by: Kent Overstreet <koverstreet@google.com>

drivers/md/bcache/request.h

@@ -0,0 +1,62 @@
+#ifndef _BCACHE_REQUEST_H_
+#define _BCACHE_REQUEST_H_
+
+#include <linux/cgroup.h>
+
+struct search {
+	/* Stack frame for bio_complete */
+	struct closure		cl;
+
+	struct bcache_device	*d;
+	struct task_struct	*task;
+
+	struct bbio		bio;
+	struct bio		*orig_bio;
+	struct bio		*cache_miss;
+	unsigned		cache_bio_sectors;
+
+	unsigned		recoverable:1;
+	unsigned		unaligned_bvec:1;
+
+	unsigned		write:1;
+	unsigned		writeback:1;
+
+	/* IO error returned to s->bio */
+	short			error;
+	unsigned long		start_time;
+
+	/* Anything past op->keys won't get zeroed in do_bio_hook */
+	struct btree_op		op;
+};
+
+void bch_cache_read_endio(struct bio *, int);
+int bch_get_congested(struct cache_set *);
+void bch_insert_data(struct closure *cl);
+void bch_btree_insert_async(struct closure *);
+void bch_cache_read_endio(struct bio *, int);
+
+void bch_open_buckets_free(struct cache_set *);
+int bch_open_buckets_alloc(struct cache_set *);
+
+void bch_cached_dev_request_init(struct cached_dev *dc);
+void bch_flash_dev_request_init(struct bcache_device *d);
+
+extern struct kmem_cache *bch_search_cache, *bch_passthrough_cache;
+
+struct bch_cgroup {
+#ifdef CONFIG_CGROUP_BCACHE
+	struct cgroup_subsys_state	css;
+#endif
+	/*
+	 * We subtract one from the index into bch_cache_modes[], so that
+	 * default == -1; this makes it so the rest match up with d->cache_mode,
+	 * and we use d->cache_mode if cgrp->cache_mode < 0
+	 */
+	short				cache_mode;
+	bool				verify;
+	struct cache_stat_collector	stats;
+};
+
+struct bch_cgroup *bch_bio_to_cgroup(struct bio *bio);
+
+#endif /* _BCACHE_REQUEST_H_ */