block: Kill bi_destructor

Now that we've got generic code for freeing bios allocated from bio
pools, this isn't needed anymore.

This patch also makes bio_free() static, since without bi_destructor
there should be no need for it to be called anywhere else.

bio_free() is now only called from bio_put, so we can refactor those a
bit - move some code from bio_put() to bio_free() and kill the redundant
bio->bi_next = NULL.

v5: Switch to BIO_KMALLOC_POOL ((void *)~0), per Boaz
v6: BIO_KMALLOC_POOL now NULL, drop bio_free's EXPORT_SYMBOL
v7: No #define BIO_KMALLOC_POOL anymore

Signed-off-by: Kent Overstreet <koverstreet@google.com>
CC: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

5 files changed, 27 insertions, 48 deletions

diff --git a/Documentation/block/biodoc.txt b/Documentation/block/biodoc.txt
index e418dc0a7086..8df5e8e6dceb 100644
--- a/Documentation/block/biodoc.txt
+++ b/Documentation/block/biodoc.txt
@@ -465,7 +465,6 @@ struct bio {
        bio_end_io_t     *bi_end_io;  /* bi_end_io (bio) */
        atomic_t         bi_cnt;      /* pin count: free when it hits zero */
        void             *bi_private;
-       bio_destructor_t *bi_destructor; /* bi_destructor (bio) */
 };
 
 With this multipage bio design:
@@ -647,10 +646,6 @@ for a non-clone bio. There are the 6 pools setup for different size biovecs,
 so bio_alloc(gfp_mask, nr_iovecs) will allocate a vec_list of the
 given size from these slabs.
 
-The bi_destructor() routine takes into account the possibility of the bio
-having originated from a different source (see later discussions on
-n/w to block transfers and kvec_cb)
-
 The bio_get() routine may be used to hold an extra reference on a bio prior
 to i/o submission, if the bio fields are likely to be accessed after the
 i/o is issued (since the bio may otherwise get freed in case i/o completion
diff --git a/block/blk-core.c b/block/blk-core.c
index 95c493511be7..b776cc90a4e7 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -2807,7 +2807,7 @@ int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
 
 free_and_out:
         if (bio)
-                bio_free(bio, bs);
+                bio_put(bio);
         blk_rq_unprep_clone(rq);
 
         return -ENOMEM;
diff --git a/fs/bio.c b/fs/bio.c
index 919ee9aa5c57..736ef12f5191 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -233,26 +233,37 @@ fallback:
         return bvl;
 }
 
-void bio_free(struct bio *bio, struct bio_set *bs)
+static void __bio_free(struct bio *bio)
 {
-        void *p;
-
-        if (bio_has_allocated_vec(bio))
-                bvec_free_bs(bs, bio->bi_io_vec, BIO_POOL_IDX(bio));
+        bio_disassociate_task(bio);
 
         if (bio_integrity(bio))
                 bio_integrity_free(bio);
+}
 
-        /*
-         * If we have front padding, adjust the bio pointer before freeing
-         */
-        p = bio;
-        if (bs->front_pad)
+static void bio_free(struct bio *bio)
+{
+        struct bio_set *bs = bio->bi_pool;
+        void *p;
+
+        __bio_free(bio);
+
+        if (bs) {
+                if (bio_has_allocated_vec(bio))
+                        bvec_free_bs(bs, bio->bi_io_vec, BIO_POOL_IDX(bio));
+
+                /*
+                 * If we have front padding, adjust the bio pointer before freeing
+                 */
+                p = bio;
                 p -= bs->front_pad;
 
-        mempool_free(p, bs->bio_pool);
+                mempool_free(p, bs->bio_pool);
+        } else {
+                /* Bio was allocated by bio_kmalloc() */
+                kfree(bio);
+        }
 }
-EXPORT_SYMBOL(bio_free);
 
 void bio_init(struct bio *bio)
 {
@@ -276,10 +287,7 @@ void bio_reset(struct bio *bio)
 {
         unsigned long flags = bio->bi_flags & (~0UL << BIO_RESET_BITS);
 
-        if (bio_integrity(bio))
-                bio_integrity_free(bio);
-
-        bio_disassociate_task(bio);
+        __bio_free(bio);
 
         memset(bio, 0, BIO_RESET_BYTES);
         bio->bi_flags = flags|(1 << BIO_UPTODATE);
@@ -362,13 +370,6 @@ struct bio *bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
 }
 EXPORT_SYMBOL(bio_alloc);
 
-static void bio_kmalloc_destructor(struct bio *bio)
-{
-        if (bio_integrity(bio))
-                bio_integrity_free(bio);
-        kfree(bio);
-}
-
 /**
  * bio_kmalloc - allocate a bio for I/O using kmalloc()
  * @gfp_mask:   the GFP_ mask given to the slab allocator
@@ -395,7 +396,6 @@ struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned int nr_iovecs)
         bio->bi_flags |= BIO_POOL_NONE << BIO_POOL_OFFSET;
         bio->bi_max_vecs = nr_iovecs;
         bio->bi_io_vec = bio->bi_inline_vecs;
-        bio->bi_destructor = bio_kmalloc_destructor;
 
         return bio;
 }
@@ -431,20 +431,8 @@ void bio_put(struct bio *bio)
         /*
          * last put frees it
          */
-        if (atomic_dec_and_test(&bio->bi_cnt)) {
-                bio_disassociate_task(bio);
-                bio->bi_next = NULL;
-
-                /*
-                 * This if statement is temporary - bi_pool is replacing
-                 * bi_destructor, but bi_destructor will be taken out in another
-                 * patch.
-                 */
-                if (bio->bi_pool)
-                        bio_free(bio, bio->bi_pool);
-                else
-                        bio->bi_destructor(bio);
-        }
+        if (atomic_dec_and_test(&bio->bi_cnt))
+                bio_free(bio);
 }
 EXPORT_SYMBOL(bio_put);
 
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 76f6c252baff..04944c91fae7 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -216,7 +216,6 @@ extern struct bio *bio_alloc(gfp_t, unsigned int);
 extern struct bio *bio_kmalloc(gfp_t, unsigned int);
 extern struct bio *bio_alloc_bioset(gfp_t, int, struct bio_set *);
 extern void bio_put(struct bio *);
-extern void bio_free(struct bio *, struct bio_set *);
 
 extern void bio_endio(struct bio *, int);
 struct request_queue;
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 1b607c247d72..3eefbb291192 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -84,11 +84,8 @@ struct bio {
 
         struct bio_vec          *bi_io_vec;     /* the actual vec list */
 
-        /* If bi_pool is non NULL, bi_destructor is not called */
         struct bio_set          *bi_pool;
 
-        bio_destructor_t        *bi_destructor; /* destructor */
-
         /*
          * We can inline a number of vecs at the end of the bio, to avoid
          * double allocations for a small number of bio_vecs. This member