bio: add support for inlining a number of bio_vecs inside the bio

[mirror_ubuntu-bionic-kernel.git] / fs / bio.c

diff --git a/fs/bio.c b/fs/bio.c
index 0146f80789e96210c681a043590c1c5932eb49f0..75e6be18ecd3d762fc760c66b8fbf98e90498154 100644 (file)
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -31,6 +31,12 @@
 
 DEFINE_TRACE(block_split);
 
+/*
+ * Test patch to inline a certain number of bi_io_vec's inside the bio
+ * itself, to shrink a bio data allocation from two mempool calls to one
+ */
+#define BIO_INLINE_VECS                4
+
 static mempool_t *bio_split_pool __read_mostly;
 
 /*
@@ -241,7 +247,7 @@ void bio_free(struct bio *bio, struct bio_set *bs)
 {
        void *p;
 
-       if (bio->bi_io_vec)
+       if (bio_has_allocated_vec(bio))
                bvec_free_bs(bs, bio->bi_io_vec, BIO_POOL_IDX(bio));
 
        if (bio_integrity(bio))
@@ -267,7 +273,8 @@ static void bio_fs_destructor(struct bio *bio)
 
 static void bio_kmalloc_destructor(struct bio *bio)
 {
-       kfree(bio->bi_io_vec);
+       if (bio_has_allocated_vec(bio))
+               kfree(bio->bi_io_vec);
        kfree(bio);
 }
 
@@ -314,7 +321,16 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
                if (likely(nr_iovecs)) {
                        unsigned long uninitialized_var(idx);
 
-                       bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, bs);
+                       if (nr_iovecs <= BIO_INLINE_VECS) {
+                               idx = 0;
+                               bvl = bio->bi_inline_vecs;
+                               nr_iovecs = BIO_INLINE_VECS;
+                               memset(bvl, 0, BIO_INLINE_VECS * sizeof(*bvl));
+                       } else {
+                               bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx,
+                                                       bs);
+                               nr_iovecs = bvec_nr_vecs(idx);
+                       }
                        if (unlikely(!bvl)) {
                                if (bs)
                                        mempool_free(bio, bs->bio_pool);
@@ -324,7 +340,7 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
                                goto out;
                        }
                        bio->bi_flags |= idx << BIO_POOL_OFFSET;
-                       bio->bi_max_vecs = bvec_nr_vecs(idx);
+                       bio->bi_max_vecs = nr_iovecs;
                }
                bio->bi_io_vec = bvl;
        }
@@ -1525,6 +1541,7 @@ void bioset_free(struct bio_set *bs)
  */
 struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad)
 {
+       unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
        struct bio_set *bs;
 
        bs = kzalloc(sizeof(*bs), GFP_KERNEL);
@@ -1533,7 +1550,7 @@ struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad)
 
        bs->front_pad = front_pad;
 
-       bs->bio_slab = bio_find_or_create_slab(front_pad);
+       bs->bio_slab = bio_find_or_create_slab(front_pad + back_pad);
        if (!bs->bio_slab) {
                kfree(bs);
                return NULL;