block: Convert integrity to bvec_alloc_bs()

This adds a pointer to the bvec array to struct bio_integrity_payload,
instead of the bvecs always being inline; then the bvecs are allocated
with bvec_alloc_bs().

Changed bvec_alloc_bs() and bvec_free_bs() to take a pointer to a
mempool instead of the bioset, so that bio integrity can use a different
mempool for its bvecs, and thus avoid a potential deadlock.

This is eventually for immutable bio vecs - immutable bvecs aren't
useful if we still have to copy them, hence the need for the pointer.
Less code is always nice too, though.

Also, bio_integrity_alloc() was using fs_bio_set if no bio_set was
specified. This was wrong - using the bio_set doesn't protect us from
memory allocation failures, because we just used kmalloc for the
bio_integrity_payload. But it does introduce the possibility of
deadlock, if for some reason we weren't supposed to be using fs_bio_set.

Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 15 insertions, 21 deletions

diff --git a/fs/bio.c b/fs/bio.c
index 73b544709945..40aa96eae99f 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -160,12 +160,12 @@ unsigned int bvec_nr_vecs(unsigned short idx)
         return bvec_slabs[idx].nr_vecs;
 }
 
-void bvec_free_bs(struct bio_set *bs, struct bio_vec *bv, unsigned int idx)
+void bvec_free(mempool_t *pool, struct bio_vec *bv, unsigned int idx)
 {
         BIO_BUG_ON(idx >= BIOVEC_NR_POOLS);
 
         if (idx == BIOVEC_MAX_IDX)
-                mempool_free(bv, bs->bvec_pool);
+                mempool_free(bv, pool);
         else {
                 struct biovec_slab *bvs = bvec_slabs + idx;
 
@@ -173,8 +173,8 @@ void bvec_free_bs(struct bio_set *bs, struct bio_vec *bv, unsigned int idx)
         }
 }
 
-struct bio_vec *bvec_alloc_bs(gfp_t gfp_mask, int nr, unsigned long *idx,
-                              struct bio_set *bs)
+struct bio_vec *bvec_alloc(gfp_t gfp_mask, int nr, unsigned long *idx,
+                           mempool_t *pool)
 {
         struct bio_vec *bvl;
 
@@ -210,7 +210,7 @@ struct bio_vec *bvec_alloc_bs(gfp_t gfp_mask, int nr, unsigned long *idx,
          */
         if (*idx == BIOVEC_MAX_IDX) {
 fallback:
-                bvl = mempool_alloc(bs->bvec_pool, gfp_mask);
+                bvl = mempool_alloc(pool, gfp_mask);
         } else {
                 struct biovec_slab *bvs = bvec_slabs + *idx;
                 gfp_t __gfp_mask = gfp_mask & ~(__GFP_WAIT | __GFP_IO);
@@ -253,7 +253,7 @@ static void bio_free(struct bio *bio)
 
         if (bs) {
                 if (bio_has_allocated_vec(bio))
-                        bvec_free_bs(bs, bio->bi_io_vec, BIO_POOL_IDX(bio));
+                        bvec_free(bs->bvec_pool, bio->bi_io_vec, BIO_POOL_IDX(bio));
 
                 /*
                  * If we have front padding, adjust the bio pointer before freeing
@@ -442,11 +442,11 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
         bio_init(bio);
 
         if (nr_iovecs > inline_vecs) {
-                bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, bs);
+                bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx, bs->bvec_pool);
                 if (!bvl && gfp_mask != saved_gfp) {
                         punt_bios_to_rescuer(bs);
                         gfp_mask = saved_gfp;
-                        bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, bs);
+                        bvl = bvec_alloc(gfp_mask, nr_iovecs, &idx, bs->bvec_pool);
                 }
 
                 if (unlikely(!bvl))
@@ -1661,20 +1661,11 @@ EXPORT_SYMBOL(bio_sector_offset);
  * create memory pools for biovec's in a bio_set.
  * use the global biovec slabs created for general use.
  */
-static int biovec_create_pools(struct bio_set *bs, int pool_entries)
+mempool_t *biovec_create_pool(struct bio_set *bs, int pool_entries)
 {
         struct biovec_slab *bp = bvec_slabs + BIOVEC_MAX_IDX;
 
-        bs->bvec_pool = mempool_create_slab_pool(pool_entries, bp->slab);
-        if (!bs->bvec_pool)
-                return -ENOMEM;
-
-        return 0;
-}
-
-static void biovec_free_pools(struct bio_set *bs)
-{
-        mempool_destroy(bs->bvec_pool);
+        return mempool_create_slab_pool(pool_entries, bp->slab);
 }
 
 void bioset_free(struct bio_set *bs)
@@ -1685,8 +1676,10 @@ void bioset_free(struct bio_set *bs)
         if (bs->bio_pool)
                 mempool_destroy(bs->bio_pool);
 
+        if (bs->bvec_pool)
+                mempool_destroy(bs->bvec_pool);
+
         bioset_integrity_free(bs);
-        biovec_free_pools(bs);
         bio_put_slab(bs);
 
         kfree(bs);
@@ -1731,7 +1724,8 @@ struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad)
         if (!bs->bio_pool)
                 goto bad;
 
-        if (biovec_create_pools(bs, pool_size))
+        bs->bvec_pool = biovec_create_pool(bs, pool_size);
+        if (!bs->bvec_pool)
                 goto bad;
 
         bs->rescue_workqueue = alloc_workqueue("bioset", WQ_MEM_RECLAIM, 0);