dm: introduce the target flag mempool_needs_integrity

This commit introduces the dm target flag mempool_needs_integrity. When
the flag is set, device mapper will call bioset_integrity_create on it's
bio sets. The target can then call bio_integrity_alloc on the bios
allocated from the table's mempool.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

drivers/md/dm-table.c

@@ -1050,6 +1050,7 @@ static int dm_table_alloc_md_mempools(struct dm_table *t, struct mapped_device *
 	unsigned int min_pool_size = 0, pool_size;
 	struct dm_md_mempools *pools;
 	unsigned int bioset_flags = 0;
+	bool mempool_needs_integrity = t->integrity_supported;
 
 	if (unlikely(type == DM_TYPE_NONE)) {
 		DMERR("no table type is set, can't allocate mempools");
@@ -1074,6 +1075,8 @@ static int dm_table_alloc_md_mempools(struct dm_table *t, struct mapped_device *
 
 		per_io_data_size = max(per_io_data_size, ti->per_io_data_size);
 		min_pool_size = max(min_pool_size, ti->num_flush_bios);
+
+		mempool_needs_integrity |= ti->mempool_needs_integrity;
 	}
 	pool_size = max(dm_get_reserved_bio_based_ios(), min_pool_size);
 	front_pad = roundup(per_io_data_size,
@@ -1083,13 +1086,13 @@ static int dm_table_alloc_md_mempools(struct dm_table *t, struct mapped_device *
 		__alignof__(struct dm_io)) + DM_IO_BIO_OFFSET;
 	if (bioset_init(&pools->io_bs, pool_size, io_front_pad, bioset_flags))
 		goto out_free_pools;
-	if (t->integrity_supported &&
+	if (mempool_needs_integrity &&
 	    bioset_integrity_create(&pools->io_bs, pool_size))
 		goto out_free_pools;
 init_bs:
 	if (bioset_init(&pools->bs, pool_size, front_pad, 0))
 		goto out_free_pools;
-	if (t->integrity_supported &&
+	if (mempool_needs_integrity &&
 	    bioset_integrity_create(&pools->bs, pool_size))
 		goto out_free_pools;
 

include/linux/device-mapper.h

@@ -405,6 +405,12 @@ struct dm_target {
 	 * support it.
 	 */
 	bool flush_bypasses_map:1;
+
+	/*
+	 * Set if the target calls bio_integrity_alloc on bios received
+	 * in the map method.
+	 */
+	bool mempool_needs_integrity:1;
 };
 
 void *dm_per_bio_data(struct bio *bio, size_t data_size);