Commit 697e2349 authored by Coly Li's avatar Coly Li Committed by Jens Axboe
Browse files

bcache: explicitly make cache_set only have single cache 



Currently although the bcache code has a framework for multiple caches
in a cache set, but indeed the multiple caches never completed and users
use md raid1 for multiple copies of the cached data.

This patch does the following change in struct cache_set, to explicitly
make a cache_set only have single cache,
- Change pointer array "*cache[MAX_CACHES_PER_SET]" to a single pointer
  "*cache".
- Remove pointer array "*cache_by_alloc[MAX_CACHES_PER_SET]".
- Remove "caches_loaded".

Now the code looks as exactly what it does in practic: only one cache is
used in the cache set.

Signed-off-by: default avatarColy Li <colyli@suse.de>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 17e4aed8

drivers/md/bcache/alloc.c

+1 −1
Original line number Diff line number Diff line
@@ -501,7 +501,7 @@ int __bch_bucket_alloc_set(struct cache_set *c, unsigned int reserve, 


	bkey_init(k);



	ca = c->cache_by_alloc[0];

	ca = c->cache;

	b = bch_bucket_alloc(ca, reserve, wait);

	if (b == -1)

		goto err;

drivers/md/bcache/bcache.h

+3 −5
Original line number Diff line number Diff line
@@ -519,9 +519,7 @@ struct cache_set { 


	struct cache_sb		sb;



	struct cache		*cache[MAX_CACHES_PER_SET];

	struct cache		*cache_by_alloc[MAX_CACHES_PER_SET];

	int			caches_loaded;

	struct cache		*cache;



	struct bcache_device	**devices;

	unsigned int		devices_max_used;
@@ -808,7 +806,7 @@ static inline struct cache *PTR_CACHE(struct cache_set *c, 
				      const struct bkey *k,

				      unsigned int ptr)

{

	return c->cache[PTR_DEV(k, ptr)];

	return c->cache;

}



static inline size_t PTR_BUCKET_NR(struct cache_set *c,
@@ -890,7 +888,7 @@ do { \ 
/* Looping macros */



#define for_each_cache(ca, cs, iter)					\

	for (iter = 0; ca = cs->cache[iter], iter < (cs)->sb.nr_in_set; iter++)

	for (iter = 0; ca = cs->cache, iter < 1; iter++)



#define for_each_bucket(b, ca)						\

	for (b = (ca)->buckets + (ca)->sb.first_bucket;			\

drivers/md/bcache/super.c

+8 −11
Original line number Diff line number Diff line
@@ -1674,7 +1674,7 @@ static void cache_set_free(struct closure *cl) 
	for_each_cache(ca, c, i)

		if (ca) {

			ca->set = NULL;

			c->cache[ca->sb.nr_this_dev] = NULL;

			c->cache = NULL;

			kobject_put(&ca->kobj);

		}
@@ -2165,7 +2165,7 @@ static const char *register_cache_set(struct cache *ca) 


	list_for_each_entry(c, &bch_cache_sets, list)

		if (!memcmp(c->sb.set_uuid, ca->sb.set_uuid, 16)) {

			if (c->cache[ca->sb.nr_this_dev])

			if (c->cache)

				return "duplicate cache set member";



			if (!can_attach_cache(ca, c))
@@ -2215,14 +2215,11 @@ found: 


	kobject_get(&ca->kobj);

	ca->set = c;

	ca->set->cache[ca->sb.nr_this_dev] = ca;

	c->cache_by_alloc[c->caches_loaded++] = ca;

	ca->set->cache = ca;



	if (c->caches_loaded == c->sb.nr_in_set) {

	err = "failed to run cache set";

	if (run_cache_set(c) < 0)

		goto err;

	}



	return NULL;

err:
@@ -2239,8 +2236,8 @@ void bch_cache_release(struct kobject *kobj) 
	unsigned int i;



	if (ca->set) {

		BUG_ON(ca->set->cache[ca->sb.nr_this_dev] != ca);

		ca->set->cache[ca->sb.nr_this_dev] = NULL;

		BUG_ON(ca->set->cache != ca);

		ca->set->cache = NULL;

	}



	free_pages((unsigned long) ca->disk_buckets, ilog2(meta_bucket_pages(&ca->sb)));

CRA Git | Maintained and supported by SUSTech CRA and CCSE