bcache: handle c->uuids properly for bucket size > 8MB

Bcache allocates a whole bucket to store c->uuids on cache device, and
allocates continuous pages to store it in-memory. When the bucket size
exceeds maximum allocable continuous pages, bch_cache_set_alloc() will
fail and cache device registration will fail.

This patch allocates c->uuids by alloc_meta_bucket_pages(), and uses
ilog2(meta_bucket_pages(c)) to indicate order of c->uuids pages when
free it. When writing c->uuids to cache device, its size is decided
by meta_bucket_pages(c) * PAGE_SECTORS. Now c->uuids is properly handled
for bucket size > 8MB.

Signed-off-by: Coly Li <[email protected]>
Reviewed-by: Hannes Reinecke <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

Author: Coly Li

drivers/md/bcache/super.c

@@ -466,14 +466,16 @@ static int __uuid_write(struct cache_set *c)
 	BKEY_PADDED(key) k;
 	struct closure cl;
 	struct cache *ca;
+	unsigned int size;
 
 	closure_init_stack(&cl);
 	lockdep_assert_held(&bch_register_lock);
 
 	if (bch_bucket_alloc_set(c, RESERVE_BTREE, &k.key, 1, true))
 		return 1;
 
-	SET_KEY_SIZE(&k.key, c->sb.bucket_size);
+	size =  meta_bucket_pages(&c->sb) * PAGE_SECTORS;
+	SET_KEY_SIZE(&k.key, size);
 	uuid_io(c, REQ_OP_WRITE, 0, &k.key, &cl);
 	closure_sync(&cl);
 
@@ -1664,7 +1666,7 @@ static void cache_set_free(struct closure *cl)
 		}
 
 	bch_bset_sort_state_free(&c->sort);
-	free_pages((unsigned long) c->uuids, ilog2(bucket_pages(c)));
+	free_pages((unsigned long) c->uuids, ilog2(meta_bucket_pages(&c->sb)));
 
 	if (c->moving_gc_wq)
 		destroy_workqueue(c->moving_gc_wq);
@@ -1870,7 +1872,7 @@ struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
 
 	c->bucket_bits		= ilog2(sb->bucket_size);
 	c->block_bits		= ilog2(sb->block_size);
-	c->nr_uuids		= bucket_bytes(c) / sizeof(struct uuid_entry);
+	c->nr_uuids		= meta_bucket_bytes(&c->sb) / sizeof(struct uuid_entry);
 	c->devices_max_used	= 0;
 	atomic_set(&c->attached_dev_nr, 0);
 	c->btree_pages		= bucket_pages(c);
@@ -1921,7 +1923,7 @@ struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
 			BIOSET_NEED_BVECS|BIOSET_NEED_RESCUER))
 		goto err;
 
-	c->uuids = alloc_bucket_pages(GFP_KERNEL, c);
+	c->uuids = alloc_meta_bucket_pages(GFP_KERNEL, &c->sb);
 	if (!c->uuids)
 		goto err;