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>

3 files changed, 68 insertions, 108 deletions

diff --git a/fs/bio-integrity.c b/fs/bio-integrity.c
index 94fa1c562c0e..8c4c604c840d 100644
--- a/fs/bio-integrity.c
+++ b/fs/bio-integrity.c
@@ -27,48 +27,11 @@
 #include <linux/workqueue.h>
 #include <linux/slab.h>
 
-struct integrity_slab {
-        struct kmem_cache *slab;
-        unsigned short nr_vecs;
-        char name[8];
-};
-
-#define IS(x) { .nr_vecs = x, .name = "bip-"__stringify(x) }
-struct integrity_slab bip_slab[BIOVEC_NR_POOLS] __read_mostly = {
-        IS(1), IS(4), IS(16), IS(64), IS(128), IS(BIO_MAX_PAGES),
-};
-#undef IS
+#define BIP_INLINE_VECS 4
 
+static struct kmem_cache *bip_slab;
 static struct workqueue_struct *kintegrityd_wq;
 
-static inline unsigned int vecs_to_idx(unsigned int nr)
-{
-        switch (nr) {
-        case 1:
-                return 0;
-        case 2 ... 4:
-                return 1;
-        case 5 ... 16:
-                return 2;
-        case 17 ... 64:
-                return 3;
-        case 65 ... 128:
-                return 4;
-        case 129 ... BIO_MAX_PAGES:
-                return 5;
-        default:
-                BUG();
-        }
-}
-
-static inline int use_bip_pool(unsigned int idx)
-{
-        if (idx == BIOVEC_MAX_IDX)
-                return 1;
-
-        return 0;
-}
-
 /**
  * bio_integrity_alloc - Allocate integrity payload and attach it to bio
  * @bio:        bio to attach integrity metadata to
@@ -84,38 +47,41 @@ struct bio_integrity_payload *bio_integrity_alloc(struct bio *bio,
                                                   unsigned int nr_vecs)
 {
         struct bio_integrity_payload *bip;
-        unsigned int idx = vecs_to_idx(nr_vecs);
         struct bio_set *bs = bio->bi_pool;
-
-        if (!bs)
-                bs = fs_bio_set;
-
-        BUG_ON(bio == NULL);
-        bip = NULL;
-
-        /* Lower order allocations come straight from slab */
-        if (!use_bip_pool(idx))
-                bip = kmem_cache_alloc(bip_slab[idx].slab, gfp_mask);
-
-        /* Use mempool if lower order alloc failed or max vecs were requested */
-        if (bip == NULL) {
-                idx = BIOVEC_MAX_IDX;  /* so we free the payload properly later */
+        unsigned long idx = BIO_POOL_NONE;
+        unsigned inline_vecs;
+
+        if (!bs) {
+                bip = kmalloc(sizeof(struct bio_integrity_payload) +
+                              sizeof(struct bio_vec) * nr_vecs, gfp_mask);
+                inline_vecs = nr_vecs;
+        } else {
                 bip = mempool_alloc(bs->bio_integrity_pool, gfp_mask);
-
-                if (unlikely(bip == NULL)) {
-                        printk(KERN_ERR "%s: could not alloc bip\n", __func__);
-                        return NULL;
-                }
+                inline_vecs = BIP_INLINE_VECS;
         }
 
+        if (unlikely(!bip))
+                return NULL;
+
         memset(bip, 0, sizeof(*bip));
 
+        if (nr_vecs > inline_vecs) {
+                bip->bip_vec = bvec_alloc(gfp_mask, nr_vecs, &idx,
+                                          bs->bvec_integrity_pool);
+                if (!bip->bip_vec)
+                        goto err;
+        } else {
+                bip->bip_vec = bip->bip_inline_vecs;
+        }
+
         bip->bip_slab = idx;
         bip->bip_bio = bio;
-        bip->bip_vec = bip->bip_inline_vecs;
         bio->bi_integrity = bip;
 
         return bip;
+err:
+        mempool_free(bip, bs->bio_integrity_pool);
+        return NULL;
 }
 EXPORT_SYMBOL(bio_integrity_alloc);
 
@@ -131,20 +97,20 @@ void bio_integrity_free(struct bio *bio)
         struct bio_integrity_payload *bip = bio->bi_integrity;
         struct bio_set *bs = bio->bi_pool;
 
-        if (!bs)
-                bs = fs_bio_set;
-
-        BUG_ON(bip == NULL);
-
         /* A cloned bio doesn't own the integrity metadata */
         if (!bio_flagged(bio, BIO_CLONED) && !bio_flagged(bio, BIO_FS_INTEGRITY)
             && bip->bip_buf != NULL)
                 kfree(bip->bip_buf);
 
-        if (use_bip_pool(bip->bip_slab))
+        if (bs) {
+                if (bip->bip_slab != BIO_POOL_NONE)
+                        bvec_free(bs->bvec_integrity_pool, bip->bip_vec,
+                                  bip->bip_slab);
+
                 mempool_free(bip, bs->bio_integrity_pool);
-        else
-                kmem_cache_free(bip_slab[bip->bip_slab].slab, bip);
+        } else {
+                kfree(bip);
+        }
 
         bio->bi_integrity = NULL;
 }
@@ -747,13 +713,14 @@ EXPORT_SYMBOL(bio_integrity_clone);
 
 int bioset_integrity_create(struct bio_set *bs, int pool_size)
 {
-        unsigned int max_slab = vecs_to_idx(BIO_MAX_PAGES);
-
         if (bs->bio_integrity_pool)
                 return 0;
 
-        bs->bio_integrity_pool =
-                mempool_create_slab_pool(pool_size, bip_slab[max_slab].slab);
+        bs->bio_integrity_pool = mempool_create_slab_pool(pool_size, bip_slab);
+
+        bs->bvec_integrity_pool = biovec_create_pool(bs, pool_size);
+        if (!bs->bvec_integrity_pool)
+                return -1;
 
         if (!bs->bio_integrity_pool)
                 return -1;
@@ -766,13 +733,14 @@ void bioset_integrity_free(struct bio_set *bs)
 {
         if (bs->bio_integrity_pool)
                 mempool_destroy(bs->bio_integrity_pool);
+
+        if (bs->bvec_integrity_pool)
+                mempool_destroy(bs->bio_integrity_pool);
 }
 EXPORT_SYMBOL(bioset_integrity_free);
 
 void __init bio_integrity_init(void)
 {
-        unsigned int i;
-
         /*
          * kintegrityd won't block much but may burn a lot of CPU cycles.
          * Make it highpri CPU intensive wq with max concurrency of 1.
@@ -782,14 +750,10 @@ void __init bio_integrity_init(void)
         if (!kintegrityd_wq)
                 panic("Failed to create kintegrityd\n");
 
-        for (i = 0 ; i < BIOVEC_NR_POOLS ; i++) {
-                unsigned int size;
-
-                size = sizeof(struct bio_integrity_payload)
-                        + bip_slab[i].nr_vecs * sizeof(struct bio_vec);
-
-                bip_slab[i].slab =
-                        kmem_cache_create(bip_slab[i].name, size, 0,
-                                          SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
-        }
+        bip_slab = kmem_cache_create("bio_integrity_payload",
+                                     sizeof(struct bio_integrity_payload) +
+                                     sizeof(struct bio_vec) * BIP_INLINE_VECS,
+                                     0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
+        if (!bip_slab)
+                panic("Failed to create slab\n");
 }
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);
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 81004fdcc277..669b1cb18fee 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -213,6 +213,7 @@ extern void bio_pair_release(struct bio_pair *dbio);
 
 extern struct bio_set *bioset_create(unsigned int, unsigned int);
 extern void bioset_free(struct bio_set *);
+extern mempool_t *biovec_create_pool(struct bio_set *bs, int pool_entries);
 
 extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
 extern void bio_put(struct bio *);
@@ -288,8 +289,8 @@ extern struct bio *bio_copy_user_iov(struct request_queue *,
                                      int, int, gfp_t);
 extern int bio_uncopy_user(struct bio *);
 void zero_fill_bio(struct bio *bio);
-extern struct bio_vec *bvec_alloc_bs(gfp_t, int, unsigned long *, struct bio_set *);
-extern void bvec_free_bs(struct bio_set *, struct bio_vec *, unsigned int);
+extern struct bio_vec *bvec_alloc(gfp_t, int, unsigned long *, mempool_t *);
+extern void bvec_free(mempool_t *, struct bio_vec *, unsigned int);
 extern unsigned int bvec_nr_vecs(unsigned short idx);
 
 #ifdef CONFIG_BLK_CGROUP
@@ -511,10 +512,11 @@ struct bio_set {
         unsigned int front_pad;
 
         mempool_t *bio_pool;
+        mempool_t *bvec_pool;
 #if defined(CONFIG_BLK_DEV_INTEGRITY)
         mempool_t *bio_integrity_pool;
+        mempool_t *bvec_integrity_pool;
 #endif
-        mempool_t *bvec_pool;
 
         /*
          * Deadlock avoidance for stacking block drivers: see comments in