path: root/drivers/md/bcache/request.c

/*
 * Main bcache entry point - handle a read or a write request and decide what to
 * do with it; the make_request functions are called by the block layer.
 *
 * Copyright 2010, 2011 Kent Overstreet <kent.overstreet@gmail.com>
 * Copyright 2012 Google, Inc.
 */

#include "bcache.h"
#include "btree.h"
#include "debug.h"
#include "request.h"
#include "writeback.h"

#include <linux/module.h>
#include <linux/hash.h>
#include <linux/random.h>

#include <trace/events/bcache.h>

#define CUTOFF_CACHE_ADD	95
#define CUTOFF_CACHE_READA	90

struct kmem_cache *bch_search_cache;

static void bch_data_insert_start(struct closure *);

static unsigned cache_mode(struct cached_dev *dc, struct bio *bio)
{
	return BDEV_CACHE_MODE(&dc->sb);
}

static bool verify(struct cached_dev *dc, struct bio *bio)
{
	return dc->verify;
}

static void bio_csum(struct bio *bio, struct bkey *k)
{
	struct bio_vec bv;
	struct bvec_iter iter;
	uint64_t csum = 0;

	bio_for_each_segment(bv, bio, iter) {
		void *d = kmap(bv.bv_page) + bv.bv_offset;
		csum = bch_crc64_update(csum, d, bv.bv_len);
		kunmap(bv.bv_page);
	}

	k->ptr[KEY_PTRS(k)] = csum & (~0ULL >> 1);
}

/* Insert data into cache */

static void bch_data_insert_keys(struct closure *cl)
{
	struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
	atomic_t *journal_ref = NULL;
	struct bkey *replace_key = op->replace ? &op->replace_key : NULL;
	int ret;

	/*
	 * If we're looping, might already be waiting on
	 * another journal write - can't wait on more than one journal write at
	 * a time
	 *
	 * XXX: this looks wrong
	 */
#if 0
	while (atomic_read(&s->cl.remaining) & CLOSURE_WAITING)
		closure_sync(&s->cl);
#endif

	if (!op->replace)
		journal_ref = bch_journal(op->c, &op->insert_keys,
					  op->flush_journal ? cl : NULL);

	ret = bch_btree_insert(op->c, &op->insert_keys,
			       journal_ref, replace_key);
	if (ret == -ESRCH) {
		op->replace_collision = true;
	} else if (ret) {
		op->error		= -ENOMEM;
		op->insert_data_done	= true;
	}

	if (journal_ref)
		atomic_dec_bug(journal_ref);

	if (!op->insert_data_done)
		continue_at(cl, bch_data_insert_start, op->wq);

	bch_keylist_free(&op->insert_keys);
	closure_return(cl);
}

static int bch_keylist_realloc(struct keylist *l, unsigned u64s,
			       struct cache_set *c)
{
	size_t oldsize = bch_keylist_nkeys(l);
	size_t newsize = oldsize + u64s;

	/*
	 * The journalling code doesn't handle the case where the keys to insert
	 * is bigger than an empty write: If we just return -ENOMEM here,
	 * bio_insert() and bio_invalidate() will insert the keys created so far
	 * and finish the rest when the keylist is empty.
	 */
	if (newsize * sizeof(uint64_t) > block_bytes(c) - sizeof(struct jset))
		return -ENOMEM;

	return __bch_keylist_realloc(l, u64s);
}

static void bch_data_invalidate(struct closure *cl)
{
	struct data_insert_op *op = container_of(cl, struct data_insert_op, cl);
	struct bio