bio: only mempool back the largest bio_vec slab cache
We only very rarely need the mempool backing, so it makes sense to
get rid of all but one of the mempool in a bio_set. So keep the
largest bio_vec count mempool so we can always honor the largest
allocation, and "upgrade" callers that fail.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fs/bio.c b/fs/bio.c
index df99c88..eb6b468 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -58,7 +58,8 @@
return bvec_slabs[idx].nr_vecs;
}
-struct bio_vec *bvec_alloc_bs(gfp_t gfp_mask, int nr, unsigned long *idx, struct bio_set *bs)
+struct bio_vec *bvec_alloc_bs(gfp_t gfp_mask, int nr, unsigned long *idx,
+ struct bio_set *bs)
{
struct bio_vec *bvl;
@@ -67,60 +68,90 @@
* If not, this is a bio_kmalloc() allocation and just do a
* kzalloc() for the exact number of vecs right away.
*/
- if (bs) {
- /*
- * see comment near bvec_array define!
- */
- switch (nr) {
- case 1:
- *idx = 0;
- break;
- case 2 ... 4:
- *idx = 1;
- break;
- case 5 ... 16:
- *idx = 2;
- break;
- case 17 ... 64:
- *idx = 3;
- break;
- case 65 ... 128:
- *idx = 4;
- break;
- case 129 ... BIO_MAX_PAGES:
- *idx = 5;
- break;
- default:
- return NULL;
- }
+ if (!bs)
+ bvl = kzalloc(nr * sizeof(struct bio_vec), gfp_mask);
+
+ /*
+ * see comment near bvec_array define!
+ */
+ switch (nr) {
+ case 1:
+ *idx = 0;
+ break;
+ case 2 ... 4:
+ *idx = 1;
+ break;
+ case 5 ... 16:
+ *idx = 2;
+ break;
+ case 17 ... 64:
+ *idx = 3;
+ break;
+ case 65 ... 128:
+ *idx = 4;
+ break;
+ case 129 ... BIO_MAX_PAGES:
+ *idx = 5;
+ break;
+ default:
+ return NULL;
+ }
+
+ /*
+ * idx now points to the pool we want to allocate from. only the
+ * 1-vec entry pool is mempool backed.
+ */
+ if (*idx == BIOVEC_MAX_IDX) {
+fallback:
+ bvl = mempool_alloc(bs->bvec_pool, gfp_mask);
+ } else {
+ struct biovec_slab *bvs = bvec_slabs + *idx;
+ gfp_t __gfp_mask = gfp_mask & ~(__GFP_WAIT | __GFP_IO);
/*
- * idx now points to the pool we want to allocate from
+ * Make this allocation restricted and don't dump info on
+ * allocation failures, since we'll fallback to the mempool
+ * in case of failure.
*/
- bvl = mempool_alloc(bs->bvec_pools[*idx], gfp_mask);
- if (bvl)
- memset(bvl, 0,
- bvec_nr_vecs(*idx) * sizeof(struct bio_vec));
- } else
- bvl = kzalloc(nr * sizeof(struct bio_vec), gfp_mask);
+ __gfp_mask |= __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;
+
+ /*
+ * Try a slab allocation. If this fails and __GFP_WAIT
+ * is set, retry with the 1-entry mempool
+ */
+ bvl = kmem_cache_alloc(bvs->slab, __gfp_mask);
+ if (unlikely(!bvl && (gfp_mask & __GFP_WAIT))) {
+ *idx = BIOVEC_MAX_IDX;
+ goto fallback;
+ }
+ }
+
+ if (bvl)
+ memset(bvl, 0, bvec_nr_vecs(*idx) * sizeof(struct bio_vec));
return bvl;
}
-void bio_free(struct bio *bio, struct bio_set *bio_set)
+void bio_free(struct bio *bio, struct bio_set *bs)
{
if (bio->bi_io_vec) {
const int pool_idx = BIO_POOL_IDX(bio);
BIO_BUG_ON(pool_idx >= BIOVEC_NR_POOLS);
- mempool_free(bio->bi_io_vec, bio_set->bvec_pools[pool_idx]);
+ if (pool_idx == BIOVEC_MAX_IDX)
+ mempool_free(bio->bi_io_vec, bs->bvec_pool);
+ else {
+ struct biovec_slab *bvs = bvec_slabs + pool_idx;
+
+ kmem_cache_free(bvs->slab, bio->bi_io_vec);
+ }
}
if (bio_integrity(bio))
- bio_integrity_free(bio, bio_set);
+ bio_integrity_free(bio, bs);
- mempool_free(bio, bio_set->bio_pool);
+ mempool_free(bio, bs->bio_pool);
}
/*
@@ -1346,30 +1377,18 @@
*/
static int biovec_create_pools(struct bio_set *bs, int pool_entries)
{
- int i;
+ struct biovec_slab *bp = bvec_slabs + BIOVEC_MAX_IDX;
- for (i = 0; i < BIOVEC_NR_POOLS; i++) {
- struct biovec_slab *bp = bvec_slabs + i;
- mempool_t **bvp = bs->bvec_pools + i;
+ bs->bvec_pool = mempool_create_slab_pool(pool_entries, bp->slab);
+ if (!bs->bvec_pool)
+ return -ENOMEM;
- *bvp = mempool_create_slab_pool(pool_entries, bp->slab);
- if (!*bvp)
- return -ENOMEM;
- }
return 0;
}
static void biovec_free_pools(struct bio_set *bs)
{
- int i;
-
- for (i = 0; i < BIOVEC_NR_POOLS; i++) {
- mempool_t *bvp = bs->bvec_pools[i];
-
- if (bvp)
- mempool_destroy(bvp);
- }
-
+ mempool_destroy(bs->bvec_pool);
}
void bioset_free(struct bio_set *bs)