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

// SPDX-License-Identifier: GPL-2.0
/*
 * bcache journalling code, for btree insertions
 *
 * Copyright 2012 Google, Inc.
 */

#include "bcache.h"
#include "btree.h"
#include "debug.h"
#include "extents.h"

#include <trace/events/bcache.h>

/*
 * Journal replay/recovery:
 *
 * This code is all driven from run_cache_set(); we first read the journal
 * entries, do some other stuff, then we mark all the keys in the journal
 * entries (same as garbage collection would), then we replay them - reinserting
 * them into the cache in precisely the same order as they appear in the
 * journal.
 *
 * We only journal keys that go in leaf nodes, which simplifies things quite a
 * bit.
 */

static void journal_read_endio(struct bio *bio)
{
	struct closure *cl = bio->bi_private;

	closure_put(cl);
}

static int journal_read_bucket(struct cache *ca, struct list_head *list,
			       unsigned int bucket_index)
{
	struct journal_device *ja = &ca->journal;
	struct bio *bio = &ja->bio;

	struct journal_replay *i;
	struct jset *j, *data = ca->set->journal.w[0].data;
	struct closure cl;
	unsigned int len, left, offset = 0;
	int ret = 0;
	sector_t bucket = bucket_to_sector(ca->set, ca->sb.d[bucket_index]);

	closure_init_stack(&cl);

	pr_debug("reading %u\n", bucket_index);

	while (offset < ca->sb.bucket_size) {
reread:		left = ca->sb.bucket_size - offset;
		len = min_t(unsigned int, left, PAGE_SECTORS << JSET_BITS);

		bio_reset(bio, ca->bdev, REQ_OP_READ);
		bio->bi_iter.bi_sector	= bucket + offset;
		bio->bi_iter.bi_size	= len << 9;

		bio->bi_end_io	= journal_read_endio;
		bio->bi_private = &cl;
		bch_bio_map(bio, data);

		closure_bio_submit(ca->set, bio, &cl);
		closure_sync(&cl);

		/* This function could be simpler now since we no longer write
		 * journal entries that overlap bucket boundaries; this means
		 * the start of a bucket will always have a valid journal entry
		 * if it has any journal entries at all.
		 */

		j = data;
		while (len) {
			struct list_head *where;
			size_t blocks, bytes = set_bytes(j);

			if (j->magic != jset_magic(&ca->sb)) {
				pr_debug("%u: bad magic\n", bucket_index);
				return ret;
			}

			if (bytes > left << 9 ||
			    bytes > PAGE_SIZE << JSET_BITS) {
				pr_info("%u: too big, %zu bytes, offset %u\n",
					bucket_index, bytes, offset);
				return ret;
			}

			if (bytes > len << 9)
				goto reread;

			if (j->csum != csum_set(j)) {
				pr_info("%u: bad csum, %zu bytes, offset %u\n",
					bucket_index, bytes, offset);
				return ret;
			}

			blocks = set_blocks(j, block_bytes(ca));

			/*
			 * Nodes in 'list' are in linear increasing order of
			 * i->j.seq, the node on head has the smallest (oldest)
			 * journal seq, the node on tail has the biggest
			 * (latest) journal seq.
			 */

			/*
			 * Check from the oldest jset for last_seq. If
			 * i->j.seq < j->last_seq, it means the oldest jset
			 * in list is expired and useless, remove it from
			 * this list. Otherwise, j is a candidate jset for
			 * further following checks.
			 */
			while (!list_empty(list)) {
				i = list_first_entry(list,
					struct journal_replay, list);
				if (i->j.seq >= j->last_seq)
					break;
				list_del(&i->list);
				kfree(i);
			}

			/* iterate list in reverse order (from latest jset) */
			list_for_each_entry_reverse(i, list, list) {
				if (j->seq == i->j.seq)
					goto next_set;

				/*
				 * if j->seq is less than any i->j.last_seq
				 * in list, j is an expired and useless jset.
				 */
				if (j->seq < i->j.last_seq)
					goto next_set;

				/*
				 * 'where' points to first jset in list which
				 * is elder then j.
				 */
				if (j->seq > i->j.seq) {
					where = &i->list;
					goto add;
				}
			}

			where = list;
add:
			i = kmalloc(offsetof(struct journal_replay, j) +
				    bytes, GFP_KERNEL);
			if (!i)
				return -ENOMEM;
			unsafe_memcpy(&i->j, j, bytes,
				/* "bytes" was calculated by set_bytes() above */);
			/* Add to the location after 'where' points to */
			list_add(&i->list, where);
			ret = 1;

			if (j->seq > ja->seq[bucket_index])
				ja->seq[bucket_index] = j->seq;
next_set:
			offset	+= blocks * ca->sb.block_size;
			len	-= blocks * ca->sb.block_size;
			j = ((void *) j) + blocks * block_bytes(ca);
		}
	}

	return ret;
}

int bch_journal_read(struct cache_set *c, struct list_head *list)
{
#define read_bucket(b)							\
	({								\
		ret = journal_read_bucket(ca, list, b);			\
		__set_bit(b, bitmap);					\
		if (ret < 0)						\
			return ret;					\
		ret;							\
	})

	struct cache *ca = c->cache;
	int ret = 0;
	struct journal_device *ja = &ca->journal;
	DECLARE_BITMAP(bitmap, SB_JOURNAL_BUCKETS);
	unsigned int i, l, r, m;
	uint64_t seq;

	bitmap_zero(bitmap, SB_JOURNAL_BUCKETS);
	pr_debug("%u journal buckets\n", ca->sb.njournal_buckets);

	/*
	 * Read journal buckets ordered by golden ratio hash to quickly
	 * find a sequence of buckets with valid journal entries
	 */
	for (i = 0; i < ca->sb.njournal_buckets; i++) {
		/*
		 * We must try the index l with ZERO fi