block: remove the 1 and 4 vec bvec_slabs entries

All bios with up to 4 bvecs use the inline bvecs in the bio itself, so
don't bother to define bvec_slabs entries for them.  Also decruftify
the bvec_slabs definition and initialization while we're at it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/bio.c b/block/bio.c
index 321b347..ae24125 100644 (file)
--- a/block/bio.c
+++ b/block/bio.c
@@ -25,24 +25,18 @@
 #include "blk.h"
 #include "blk-rq-qos.h"
 
-struct biovec_slab {
+static struct biovec_slab {
        int nr_vecs;
        char *name;
        struct kmem_cache *slab;
+} bvec_slabs[] __read_mostly = {
+       { .nr_vecs = 16, .name = "biovec-16" },
+       { .nr_vecs = 64, .name = "biovec-64" },
+       { .nr_vecs = 128, .name = "biovec-128" },
+       { .nr_vecs = BIO_MAX_PAGES, .name = "biovec-max" },
 };
 
 /*
- * if you change this list, also change bvec_alloc or things will
- * break badly! cannot be bigger than what you can fit into an
- * unsigned short
- */
-#define BV(x, n) { .nr_vecs = x, .name = "biovec-"#n }
-static struct biovec_slab bvec_slabs[BVEC_POOL_NR] __read_mostly = {
-       BV(1, 1), BV(4, 4), BV(16, 16), BV(64, 64), BV(128, 128), BV(BIO_MAX_PAGES, max),
-};
-#undef BV
-
-/*
  * fs_bio_set is the bio_set containing bio and iovec memory pools used by
  * IO code that does not need private memory pools.
  */
@@ -176,12 +170,7 @@ struct bio_vec *bvec_alloc(gfp_t gfp_mask, int nr, unsigned long *idx,
         * see comment near bvec_array define!
         */
        switch (nr) {
-       case 1:
-               *idx = 0;
-               break;
-       case 2 ... 4:
-               *idx = 1;
-               break;
+       /* smaller bios use inline vecs */
        case 5 ... 16:
                *idx = 2;
                break;
@@ -1613,31 +1602,21 @@ int bioset_init_from_src(struct bio_set *bs, struct bio_set *src)
 }
 EXPORT_SYMBOL(bioset_init_from_src);
 
-static void __init biovec_init_slabs(void)
+static int __init init_bio(void)
 {
        int i;
 
-       for (i = 0; i < BVEC_POOL_NR; i++) {
-               int size;
-               struct biovec_slab *bvs = bvec_slabs + i;
-
-               if (bvs->nr_vecs <= BIO_INLINE_VECS) {
-                       bvs->slab = NULL;
-                       continue;
-               }
-
-               size = bvs->nr_vecs * sizeof(struct bio_vec);
-               bvs->slab = kmem_cache_create(bvs->name, size, 0,
-                                SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
-       }
-}
-
-static int __init init_bio(void)
-{
        BUILD_BUG_ON(BIO_FLAG_LAST > BVEC_POOL_OFFSET);
 
        bio_integrity_init();
-       biovec_init_slabs();
+
+       for (i = 0; i < ARRAY_SIZE(bvec_slabs); i++) {
+               struct biovec_slab *bvs = bvec_slabs + i;
+
+               bvs->slab = kmem_cache_create(bvs->name,
+                               bvs->nr_vecs * sizeof(struct bio_vec), 0,
+                               SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
+       }
 
        if (bioset_init(&fs_bio_set, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS))
                panic("bio: can't allocate bios\n");