From: Ming Lei <ming.lei@redhat.com>
Date: Mon, 11 Jan 2021 03:05:54 +0000 (+0800)
Subject: block: don't allocate inline bvecs if this bioset needn't bvecs
X-Git-Tag: baikal/mips/sdk5.9~11512^2~87
X-Git-Url: https://git.baikalelectronics.ru/sdk/?a=commitdiff_plain;h=d0d9c7e547306caa5aa9687153aaf47b7ac2d3f6;p=kernel.git

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 <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Tested-by: Pavel Begunkov <asml.silence@gmail.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/block/bio.c b/block/bio.c
index 87bf16460e0ea..8ccda51dd831b 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -89,8 +89,7 @@ fail_alloc_slab:
 
 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
index 2f1155eabaff2..5d8977aafa199 100644
--- 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