dm bio prison: pass cell memory in (6beca5eb) · Commits · e / devices / android_kernel_teracube_2e

drivers/md/dm-bio-prison.c

+72 −67

Original line number	Original line	Diff line number	Diff line
	@@ -16,7 +16,6 @@

	struct dm_bio_prison_cell {		struct dm_bio_prison_cell {
	struct hlist_node list;		struct hlist_node list;
	struct dm_bio_prison *prison;
	struct dm_cell_key key;		struct dm_cell_key key;
	struct bio *holder;		struct bio *holder;
	struct bio_list bios;		struct bio_list bios;
	@@ -87,6 +86,19 @@ void dm_bio_prison_destroy(struct dm_bio_prison *prison)
	}		}
	EXPORT_SYMBOL_GPL(dm_bio_prison_destroy);		EXPORT_SYMBOL_GPL(dm_bio_prison_destroy);

			struct dm_bio_prison_cell dm_bio_prison_alloc_cell(struct dm_bio_prison prison, gfp_t gfp)
			{
			return mempool_alloc(prison->cell_pool, gfp);
			}
			EXPORT_SYMBOL_GPL(dm_bio_prison_alloc_cell);

			void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
			struct dm_bio_prison_cell *cell)
			{
			mempool_free(cell, prison->cell_pool);
			}
			EXPORT_SYMBOL_GPL(dm_bio_prison_free_cell);

	static uint32_t hash_key(struct dm_bio_prison prison, struct dm_cell_key key)		static uint32_t hash_key(struct dm_bio_prison prison, struct dm_cell_key key)
	{		{
	const unsigned long BIG_PRIME = 4294967291UL;		const unsigned long BIG_PRIME = 4294967291UL;
	@@ -114,91 +126,86 @@ static struct dm_bio_prison_cell __search_bucket(struct hlist_head bucket,
	return NULL;		return NULL;
	}		}

	/*		static void __setup_new_cell(struct dm_bio_prison *prison,
	* This may block if a new cell needs allocating. You must ensure that		struct dm_cell_key *key,
	* cells will be unlocked even if the calling thread is blocked.		struct bio *holder,
	*		uint32_t hash,
	* Returns 1 if the cell was already held, 0 if @inmate is the new holder.		struct dm_bio_prison_cell *cell)
	*/
	int dm_bio_detain(struct dm_bio_prison prison, struct dm_cell_key key,
	struct bio inmate, struct dm_bio_prison_cell *ref)
	{		{
	int r = 1;		memcpy(&cell->key, key, sizeof(cell->key));
	unsigned long flags;		cell->holder = holder;
	uint32_t hash = hash_key(prison, key);		bio_list_init(&cell->bios);
	struct dm_bio_prison_cell cell, cell2;		hlist_add_head(&cell->list, prison->cells + hash);

	BUG_ON(hash > prison->nr_buckets);

	spin_lock_irqsave(&prison->lock, flags);

	cell = __search_bucket(prison->cells + hash, key);
	if (cell) {
	bio_list_add(&cell->bios, inmate);
	goto out;
	}		}

	/*		static int __bio_detain(struct dm_bio_prison *prison,
	* Allocate a new cell		struct dm_cell_key *key,
	*/		struct bio *inmate,
	spin_unlock_irqrestore(&prison->lock, flags);		struct dm_bio_prison_cell *cell_prealloc,
	cell2 = mempool_alloc(prison->cell_pool, GFP_NOIO);		struct dm_bio_prison_cell **cell_result)
	spin_lock_irqsave(&prison->lock, flags);		{
			uint32_t hash = hash_key(prison, key);
			struct dm_bio_prison_cell *cell;

	/*
	* We've been unlocked, so we have to double check that
	* nobody else has inserted this cell in the meantime.
	*/
	cell = __search_bucket(prison->cells + hash, key);		cell = __search_bucket(prison->cells + hash, key);
	if (cell) {		if (cell) {
	mempool_free(cell2, prison->cell_pool);		if (inmate)
	bio_list_add(&cell->bios, inmate);		bio_list_add(&cell->bios, inmate);
	goto out;		*cell_result = cell;
			return 1;
	}		}

	/*		__setup_new_cell(prison, key, inmate, hash, cell_prealloc);
	* Use new cell.		*cell_result = cell_prealloc;
	*/		return 0;
	cell = cell2;		}

	cell->prison = prison;
	memcpy(&cell->key, key, sizeof(cell->key));
	cell->holder = inmate;
	bio_list_init(&cell->bios);
	hlist_add_head(&cell->list, prison->cells + hash);

	r = 0;		static int bio_detain(struct dm_bio_prison *prison,
			struct dm_cell_key *key,
			struct bio *inmate,
			struct dm_bio_prison_cell *cell_prealloc,
			struct dm_bio_prison_cell **cell_result)
			{
			int r;
			unsigned long flags;

	out:		spin_lock_irqsave(&prison->lock, flags);
			r = __bio_detain(prison, key, inmate, cell_prealloc, cell_result);
	spin_unlock_irqrestore(&prison->lock, flags);		spin_unlock_irqrestore(&prison->lock, flags);

	*ref = cell;

	return r;		return r;
	}		}

			int dm_bio_detain(struct dm_bio_prison *prison,
			struct dm_cell_key *key,
			struct bio *inmate,
			struct dm_bio_prison_cell *cell_prealloc,
			struct dm_bio_prison_cell **cell_result)
			{
			return bio_detain(prison, key, inmate, cell_prealloc, cell_result);
			}
	EXPORT_SYMBOL_GPL(dm_bio_detain);		EXPORT_SYMBOL_GPL(dm_bio_detain);

	/*		/*
	* @inmates must have been initialised prior to this call		* @inmates must have been initialised prior to this call
	*/		*/
	static void __cell_release(struct dm_bio_prison_cell cell, struct bio_list inmates)		static void __cell_release(struct dm_bio_prison_cell *cell,
			struct bio_list *inmates)
	{		{
	struct dm_bio_prison *prison = cell->prison;

	hlist_del(&cell->list);		hlist_del(&cell->list);

	if (inmates) {		if (inmates) {
			if (cell->holder)
	bio_list_add(inmates, cell->holder);		bio_list_add(inmates, cell->holder);
	bio_list_merge(inmates, &cell->bios);		bio_list_merge(inmates, &cell->bios);
	}		}

	mempool_free(cell, prison->cell_pool);
	}		}

	void dm_cell_release(struct dm_bio_prison_cell cell, struct bio_list bios)		void dm_cell_release(struct dm_bio_prison *prison,
			struct dm_bio_prison_cell *cell,
			struct bio_list *bios)
	{		{
	unsigned long flags;		unsigned long flags;
	struct dm_bio_prison *prison = cell->prison;

	spin_lock_irqsave(&prison->lock, flags);		spin_lock_irqsave(&prison->lock, flags);
	__cell_release(cell, bios);		__cell_release(cell, bios);
	@@ -209,20 +216,18 @@ EXPORT_SYMBOL_GPL(dm_cell_release);
	/*		/*
	* Sometimes we don't want the holder, just the additional bios.		* Sometimes we don't want the holder, just the additional bios.
	*/		*/
	static void __cell_release_no_holder(struct dm_bio_prison_cell cell, struct bio_list inmates)		static void __cell_release_no_holder(struct dm_bio_prison_cell *cell,
			struct bio_list *inmates)
	{		{
	struct dm_bio_prison *prison = cell->prison;

	hlist_del(&cell->list);		hlist_del(&cell->list);
	bio_list_merge(inmates, &cell->bios);		bio_list_merge(inmates, &cell->bios);

	mempool_free(cell, prison->cell_pool);
	}		}

	void dm_cell_release_no_holder(struct dm_bio_prison_cell cell, struct bio_list inmates)		void dm_cell_release_no_holder(struct dm_bio_prison *prison,
			struct dm_bio_prison_cell *cell,
			struct bio_list *inmates)
	{		{
	unsigned long flags;		unsigned long flags;
	struct dm_bio_prison *prison = cell->prison;

	spin_lock_irqsave(&prison->lock, flags);		spin_lock_irqsave(&prison->lock, flags);
	__cell_release_no_holder(cell, inmates);		__cell_release_no_holder(cell, inmates);
	@@ -230,9 +235,9 @@ void dm_cell_release_no_holder(struct dm_bio_prison_cell *cell, struct bio_list
	}		}
	EXPORT_SYMBOL_GPL(dm_cell_release_no_holder);		EXPORT_SYMBOL_GPL(dm_cell_release_no_holder);

	void dm_cell_error(struct dm_bio_prison_cell *cell)		void dm_cell_error(struct dm_bio_prison *prison,
			struct dm_bio_prison_cell *cell)
	{		{
	struct dm_bio_prison *prison = cell->prison;
	struct bio_list bios;		struct bio_list bios;
	struct bio *bio;		struct bio *bio;
	unsigned long flags;		unsigned long flags;

drivers/md/dm-bio-prison.h

+27 −8

Original line number	Original line	Diff line number	Diff line
	@@ -35,17 +35,36 @@ struct dm_bio_prison *dm_bio_prison_create(unsigned nr_cells);
	void dm_bio_prison_destroy(struct dm_bio_prison *prison);		void dm_bio_prison_destroy(struct dm_bio_prison *prison);

	/*		/*
	* This may block if a new cell needs allocating. You must ensure that		* These two functions just wrap a mempool. This is a transitory step:
	* cells will be unlocked even if the calling thread is blocked.		* Eventually all bio prison clients should manage their own cell memory.
	*		*
	* Returns 1 if the cell was already held, 0 if @inmate is the new holder.		* Like mempool_alloc(), dm_bio_prison_alloc_cell() can only fail if called
			* in interrupt context or passed GFP_NOWAIT.
	*/		*/
	int dm_bio_detain(struct dm_bio_prison prison, struct dm_cell_key key,		struct dm_bio_prison_cell dm_bio_prison_alloc_cell(struct dm_bio_prison prison,
	struct bio inmate, struct dm_bio_prison_cell *ref);		gfp_t gfp);
			void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
			struct dm_bio_prison_cell *cell);

	void dm_cell_release(struct dm_bio_prison_cell cell, struct bio_list bios);		/*
	void dm_cell_release_no_holder(struct dm_bio_prison_cell cell, struct bio_list inmates);		* An atomic op that combines retrieving a cell, and adding a bio to it.
	void dm_cell_error(struct dm_bio_prison_cell *cell);		*
			* Returns 1 if the cell was already held, 0 if @inmate is the new holder.
			*/
			int dm_bio_detain(struct dm_bio_prison *prison,
			struct dm_cell_key *key,
			struct bio *inmate,
			struct dm_bio_prison_cell *cell_prealloc,
			struct dm_bio_prison_cell **cell_result);

			void dm_cell_release(struct dm_bio_prison *prison,
			struct dm_bio_prison_cell *cell,
			struct bio_list *bios);
			void dm_cell_release_no_holder(struct dm_bio_prison *prison,
			struct dm_bio_prison_cell *cell,
			struct bio_list *inmates);
			void dm_cell_error(struct dm_bio_prison *prison,
			struct dm_bio_prison_cell *cell);

	/----------------------------------------------------------------/		/----------------------------------------------------------------/

drivers/md/dm-thin.c

+77 −26

Original line number	Original line	Diff line number	Diff line
	@@ -229,6 +229,54 @@ struct thin_c {

	/----------------------------------------------------------------/		/----------------------------------------------------------------/

			static int bio_detain(struct pool pool, struct dm_cell_key key, struct bio *bio,
			struct dm_bio_prison_cell **cell_result)
			{
			int r;
			struct dm_bio_prison_cell *cell_prealloc;

			/*
			* Allocate a cell from the prison's mempool.
			* This might block but it can't fail.
			*/
			cell_prealloc = dm_bio_prison_alloc_cell(pool->prison, GFP_NOIO);

			r = dm_bio_detain(pool->prison, key, bio, cell_prealloc, cell_result);
			if (r)
			/*
			* We reused an old cell; we can get rid of
			* the new one.
			*/
			dm_bio_prison_free_cell(pool->prison, cell_prealloc);

			return r;
			}

			static void cell_release(struct pool *pool,
			struct dm_bio_prison_cell *cell,
			struct bio_list *bios)
			{
			dm_cell_release(pool->prison, cell, bios);
			dm_bio_prison_free_cell(pool->prison, cell);
			}

			static void cell_release_no_holder(struct pool *pool,
			struct dm_bio_prison_cell *cell,
			struct bio_list *bios)
			{
			dm_cell_release_no_holder(pool->prison, cell, bios);
			dm_bio_prison_free_cell(pool->prison, cell);
			}

			static void cell_error(struct pool *pool,
			struct dm_bio_prison_cell *cell)
			{
			dm_cell_error(pool->prison, cell);
			dm_bio_prison_free_cell(pool->prison, cell);
			}

			/----------------------------------------------------------------/

	/*		/*
	* A global list of pools that uses a struct mapped_device as a key.		* A global list of pools that uses a struct mapped_device as a key.
	*/		*/
	@@ -524,14 +572,14 @@ static void cell_defer(struct thin_c tc, struct dm_bio_prison_cell cell)
	unsigned long flags;		unsigned long flags;

	spin_lock_irqsave(&pool->lock, flags);		spin_lock_irqsave(&pool->lock, flags);
	dm_cell_release(cell, &pool->deferred_bios);		cell_release(pool, cell, &pool->deferred_bios);
	spin_unlock_irqrestore(&tc->pool->lock, flags);		spin_unlock_irqrestore(&tc->pool->lock, flags);

	wake_worker(pool);		wake_worker(pool);
	}		}

	/*		/*
	* Same as cell_defer except it omits the original holder of the cell.		* Same as cell_defer above, except it omits the original holder of the cell.
	*/		*/
	static void cell_defer_no_holder(struct thin_c tc, struct dm_bio_prison_cell cell)		static void cell_defer_no_holder(struct thin_c tc, struct dm_bio_prison_cell cell)
	{		{
	@@ -539,7 +587,7 @@ static void cell_defer_no_holder(struct thin_c tc, struct dm_bio_prison_cell c
	unsigned long flags;		unsigned long flags;

	spin_lock_irqsave(&pool->lock, flags);		spin_lock_irqsave(&pool->lock, flags);
	dm_cell_release_no_holder(cell, &pool->deferred_bios);		cell_release_no_holder(pool, cell, &pool->deferred_bios);
	spin_unlock_irqrestore(&pool->lock, flags);		spin_unlock_irqrestore(&pool->lock, flags);

	wake_worker(pool);		wake_worker(pool);
	@@ -549,13 +597,14 @@ static void process_prepared_mapping_fail(struct dm_thin_new_mapping *m)
	{		{
	if (m->bio)		if (m->bio)
	m->bio->bi_end_io = m->saved_bi_end_io;		m->bio->bi_end_io = m->saved_bi_end_io;
	dm_cell_error(m->cell);		cell_error(m->tc->pool, m->cell);
	list_del(&m->list);		list_del(&m->list);
	mempool_free(m, m->tc->pool->mapping_pool);		mempool_free(m, m->tc->pool->mapping_pool);
	}		}
	static void process_prepared_mapping(struct dm_thin_new_mapping *m)		static void process_prepared_mapping(struct dm_thin_new_mapping *m)
	{		{
	struct thin_c *tc = m->tc;		struct thin_c *tc = m->tc;
			struct pool *pool = tc->pool;
	struct bio *bio;		struct bio *bio;
	int r;		int r;

	@@ -564,7 +613,7 @@ static void process_prepared_mapping(struct dm_thin_new_mapping *m)
	bio->bi_end_io = m->saved_bi_end_io;		bio->bi_end_io = m->saved_bi_end_io;

	if (m->err) {		if (m->err) {
	dm_cell_error(m->cell);		cell_error(pool, m->cell);
	goto out;		goto out;
	}		}

	@@ -576,7 +625,7 @@ static void process_prepared_mapping(struct dm_thin_new_mapping *m)
	r = dm_thin_insert_block(tc->td, m->virt_block, m->data_block);		r = dm_thin_insert_block(tc->td, m->virt_block, m->data_block);
	if (r) {		if (r) {
	DMERR_LIMIT("dm_thin_insert_block() failed");		DMERR_LIMIT("dm_thin_insert_block() failed");
	dm_cell_error(m->cell);		cell_error(pool, m->cell);
	goto out;		goto out;
	}		}

	@@ -594,7 +643,7 @@ static void process_prepared_mapping(struct dm_thin_new_mapping *m)

	out:		out:
	list_del(&m->list);		list_del(&m->list);
	mempool_free(m, tc->pool->mapping_pool);		mempool_free(m, pool->mapping_pool);
	}		}

	static void process_prepared_discard_fail(struct dm_thin_new_mapping *m)		static void process_prepared_discard_fail(struct dm_thin_new_mapping *m)
	@@ -745,7 +794,7 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
	if (r < 0) {		if (r < 0) {
	mempool_free(m, pool->mapping_pool);		mempool_free(m, pool->mapping_pool);
	DMERR_LIMIT("dm_kcopyd_copy() failed");		DMERR_LIMIT("dm_kcopyd_copy() failed");
	dm_cell_error(cell);		cell_error(pool, cell);
	}		}
	}		}
	}		}
	@@ -811,7 +860,7 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
	if (r < 0) {		if (r < 0) {
	mempool_free(m, pool->mapping_pool);		mempool_free(m, pool->mapping_pool);
	DMERR_LIMIT("dm_kcopyd_zero() failed");		DMERR_LIMIT("dm_kcopyd_zero() failed");
	dm_cell_error(cell);		cell_error(pool, cell);
	}		}
	}		}
	}		}
	@@ -917,13 +966,13 @@ static void retry_on_resume(struct bio *bio)
	spin_unlock_irqrestore(&pool->lock, flags);		spin_unlock_irqrestore(&pool->lock, flags);
	}		}

	static void no_space(struct dm_bio_prison_cell *cell)		static void no_space(struct pool pool, struct dm_bio_prison_cell cell)
	{		{
	struct bio *bio;		struct bio *bio;
	struct bio_list bios;		struct bio_list bios;

	bio_list_init(&bios);		bio_list_init(&bios);
	dm_cell_release(cell, &bios);		cell_release(pool, cell, &bios);

	while ((bio = bio_list_pop(&bios)))		while ((bio = bio_list_pop(&bios)))
	retry_on_resume(bio);		retry_on_resume(bio);
	@@ -941,7 +990,7 @@ static void process_discard(struct thin_c tc, struct bio bio)
	struct dm_thin_new_mapping *m;		struct dm_thin_new_mapping *m;

	build_virtual_key(tc->td, block, &key);		build_virtual_key(tc->td, block, &key);
	if (dm_bio_detain(tc->pool->prison, &key, bio, &cell))		if (bio_detain(tc->pool, &key, bio, &cell))
	return;		return;

	r = dm_thin_find_block(tc->td, block, 1, &lookup_result);		r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
	@@ -953,7 +1002,7 @@ static void process_discard(struct thin_c tc, struct bio bio)
	* on this block.		* on this block.
	*/		*/
	build_data_key(tc->td, lookup_result.block, &key2);		build_data_key(tc->td, lookup_result.block, &key2);
	if (dm_bio_detain(tc->pool->prison, &key2, bio, &cell2)) {		if (bio_detain(tc->pool, &key2, bio, &cell2)) {
	cell_defer_no_holder(tc, cell);		cell_defer_no_holder(tc, cell);
	break;		break;
	}		}
	@@ -1029,13 +1078,13 @@ static void break_sharing(struct thin_c tc, struct bio bio, dm_block_t block,
	break;		break;

	case -ENOSPC:		case -ENOSPC:
	no_space(cell);		no_space(tc->pool, cell);
	break;		break;

	default:		default:
	DMERR_LIMIT("%s: alloc_data_block() failed: error = %d",		DMERR_LIMIT("%s: alloc_data_block() failed: error = %d",
	__func__, r);		__func__, r);
	dm_cell_error(cell);		cell_error(tc->pool, cell);
	break;		break;
	}		}
	}		}
	@@ -1053,7 +1102,7 @@ static void process_shared_bio(struct thin_c tc, struct bio bio,
	* of being broken so we have nothing further to do here.		* of being broken so we have nothing further to do here.
	*/		*/
	build_data_key(tc->td, lookup_result->block, &key);		build_data_key(tc->td, lookup_result->block, &key);
	if (dm_bio_detain(pool->prison, &key, bio, &cell))		if (bio_detain(pool, &key, bio, &cell))
	return;		return;

	if (bio_data_dir(bio) == WRITE && bio->bi_size)		if (bio_data_dir(bio) == WRITE && bio->bi_size)
	@@ -1074,12 +1123,13 @@ static void provision_block(struct thin_c tc, struct bio bio, dm_block_t block
	{		{
	int r;		int r;
	dm_block_t data_block;		dm_block_t data_block;
			struct pool *pool = tc->pool;

	/*		/*
	* Remap empty bios (flushes) immediately, without provisioning.		* Remap empty bios (flushes) immediately, without provisioning.
	*/		*/
	if (!bio->bi_size) {		if (!bio->bi_size) {
	inc_all_io_entry(tc->pool, bio);		inc_all_io_entry(pool, bio);
	cell_defer_no_holder(tc, cell);		cell_defer_no_holder(tc, cell);

	remap_and_issue(tc, bio, 0);		remap_and_issue(tc, bio, 0);
	@@ -1106,14 +1156,14 @@ static void provision_block(struct thin_c tc, struct bio bio, dm_block_t block
	break;		break;

	case -ENOSPC:		case -ENOSPC:
	no_space(cell);		no_space(pool, cell);
	break;		break;

	default:		default:
	DMERR_LIMIT("%s: alloc_data_block() failed: error = %d",		DMERR_LIMIT("%s: alloc_data_block() failed: error = %d",
	__func__, r);		__func__, r);
	set_pool_mode(tc->pool, PM_READ_ONLY);		set_pool_mode(pool, PM_READ_ONLY);
	dm_cell_error(cell);		cell_error(pool, cell);
	break;		break;
	}		}
	}		}
	@@ -1121,6 +1171,7 @@ static void provision_block(struct thin_c tc, struct bio bio, dm_block_t block
	static void process_bio(struct thin_c tc, struct bio bio)		static void process_bio(struct thin_c tc, struct bio bio)
	{		{
	int r;		int r;
			struct pool *pool = tc->pool;
	dm_block_t block = get_bio_block(tc, bio);		dm_block_t block = get_bio_block(tc, bio);
	struct dm_bio_prison_cell *cell;		struct dm_bio_prison_cell *cell;
	struct dm_cell_key key;		struct dm_cell_key key;
	@@ -1131,7 +1182,7 @@ static void process_bio(struct thin_c tc, struct bio bio)
	* being provisioned so we have nothing further to do here.		* being provisioned so we have nothing further to do here.
	*/		*/
	build_virtual_key(tc->td, block, &key);		build_virtual_key(tc->td, block, &key);
	if (dm_bio_detain(tc->pool->prison, &key, bio, &cell))		if (bio_detain(pool, &key, bio, &cell))
	return;		return;

	r = dm_thin_find_block(tc->td, block, 1, &lookup_result);		r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
	@@ -1139,9 +1190,9 @@ static void process_bio(struct thin_c tc, struct bio bio)
	case 0:		case 0:
	if (lookup_result.shared) {		if (lookup_result.shared) {
	process_shared_bio(tc, bio, block, &lookup_result);		process_shared_bio(tc, bio, block, &lookup_result);
	cell_defer_no_holder(tc, cell);		cell_defer_no_holder(tc, cell); /* FIXME: pass this cell into process_shared? */
	} else {		} else {
	inc_all_io_entry(tc->pool, bio);		inc_all_io_entry(pool, bio);
	cell_defer_no_holder(tc, cell);		cell_defer_no_holder(tc, cell);

	remap_and_issue(tc, bio, lookup_result.block);		remap_and_issue(tc, bio, lookup_result.block);
	@@ -1150,7 +1201,7 @@ static void process_bio(struct thin_c tc, struct bio bio)

	case -ENODATA:		case -ENODATA:
	if (bio_data_dir(bio) == READ && tc->origin_dev) {		if (bio_data_dir(bio) == READ && tc->origin_dev) {
	inc_all_io_entry(tc->pool, bio);		inc_all_io_entry(pool, bio);
	cell_defer_no_holder(tc, cell);		cell_defer_no_holder(tc, cell);

	remap_to_origin_and_issue(tc, bio);		remap_to_origin_and_issue(tc, bio);
	@@ -1429,11 +1480,11 @@ static int thin_bio_map(struct dm_target ti, struct bio bio)
	}		}

	build_virtual_key(tc->td, block, &key);		build_virtual_key(tc->td, block, &key);
	if (dm_bio_detain(tc->pool->prison, &key, bio, &cell1))		if (bio_detain(tc->pool, &key, bio, &cell1))
	return DM_MAPIO_SUBMITTED;		return DM_MAPIO_SUBMITTED;

	build_data_key(tc->td, result.block, &key);		build_data_key(tc->td, result.block, &key);
	if (dm_bio_detain(tc->pool->prison, &key, bio, &cell2)) {		if (bio_detain(tc->pool, &key, bio, &cell2)) {
	cell_defer_no_holder(tc, cell1);		cell_defer_no_holder(tc, cell1);
	return DM_MAPIO_SUBMITTED;		return DM_MAPIO_SUBMITTED;
	}		}