block: don't allocate inline bvecs if this bioset needn't bvecs

The inline bvecs won't be used if user needn't bvecs by not passing BIOSET_NEED_BVECS, so don't allocate bvecs in this situation. Reviewed-by: Christoph Hellwig <[email protected]> Signed-off-by: Ming Lei <[email protected]> Reviewed-by: Pavel Begunkov <[email protected]> Tested-by: Pavel Begunkov <[email protected]> Reviewed-by: Hannes Reinecke <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
dabrace · Jan 25, 2021 · 9f180e3 · 9f180e3
1 parent c495a17
commit 9f180e3
Show file tree

Hide file tree

Showing 2 changed files with 6 additions and 2 deletions.
diff --git a/block/bio.c b/block/bio.c
@@ -89,8 +89,7 @@ static struct bio_slab *create_bio_slab(unsigned int size)
 
 static inline unsigned int bs_bio_slab_size(struct bio_set *bs)
 {
-	return bs->front_pad + sizeof(struct bio) +
-		BIO_INLINE_VECS * sizeof(struct bio_vec);
+	return bs->front_pad + sizeof(struct bio) + bs->back_pad;
 }
 
 static struct kmem_cache *bio_find_or_create_slab(struct bio_set *bs)
@@ -1563,6 +1562,10 @@ int bioset_init(struct bio_set *bs,
 		int flags)
 {
 	bs->front_pad = front_pad;
+	if (flags & BIOSET_NEED_BVECS)
+		bs->back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
+	else
+		bs->back_pad = 0;
 
 	spin_lock_init(&bs->rescue_lock);
 	bio_list_init(&bs->rescue_list);

diff --git a/include/linux/bio.h b/include/linux/bio.h
@@ -703,6 +703,7 @@ struct bio_set {
 	mempool_t bvec_integrity_pool;
 #endif
 
+	unsigned int back_pad;
 	/*
 	 * Deadlock avoidance for stacking block drivers: see comments in
 	 * bio_alloc_bioset() for details