block: turn bio_kmalloc into a simple kmalloc wrapper

Remove the magic autofree semantics and require the callers to explicitly
call bio_init to initialize the bio.

This allows bio_free to catch accidental bio_put calls on bio_init()ed
bios as well.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Coly Li <colyli@suse.de>
Acked-by: Mike Snitzer <snitzer@kernel.org>
Link: https://lore.kernel.org/r/20220406061228.410163-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

3 files changed, 53 insertions, 50 deletions

diff --git a/block/bio.c b/block/bio.c
index 643a3a052c7e..212ccd5b5212 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -224,24 +224,13 @@ EXPORT_SYMBOL(bio_uninit);
 static void bio_free(struct bio *bio)
 {
 	struct bio_set *bs = bio->bi_pool;
-	void *p;
-
-	bio_uninit(bio);
+	void *p = bio;
 
-	if (bs) {
-		bvec_free(&bs->bvec_pool, bio->bi_io_vec, bio->bi_max_vecs);
+	WARN_ON_ONCE(!bs);
 
-		/*
-		 * If we have front padding, adjust the bio pointer before freeing
-		 */
-		p = bio;
-		p -= bs->front_pad;
-
-		mempool_free(p, &bs->bio_pool);
-	} else {
-		/* Bio was allocated by bio_kmalloc() */
-		kfree(bio);
-	}
+	bio_uninit(bio);
+	bvec_free(&bs->bvec_pool, bio->bi_io_vec, bio->bi_max_vecs);
+	mempool_free(p - bs->front_pad, &bs->bio_pool);
 }
 
 /*
@@ -568,28 +557,28 @@ err_free:
 EXPORT_SYMBOL(bio_alloc_bioset);
 
 /**
- * bio_kmalloc - kmalloc a bio for I/O
+ * bio_kmalloc - kmalloc a bio
+ * @nr_vecs:	number of bio_vecs to allocate
  * @gfp_mask:   the GFP_* mask given to the slab allocator
- * @nr_iovecs:	number of iovecs to pre-allocate
  *
- * Use kmalloc to allocate and initialize a bio.
+ * Use kmalloc to allocate a bio (including bvecs).  The bio must be initialized
+ * using bio_init() before use.  To free a bio returned from this function use
+ * kfree() after calling bio_uninit().  A bio returned from this function can
+ * be reused by calling bio_uninit() before calling bio_init() again.
+ *
+ * Note that unlike bio_alloc() or bio_alloc_bioset() allocations from this
+ * function are not backed by a mempool can can fail.  Do not use this function
+ * for allocations in the file system I/O path.
  *
  * Returns: Pointer to new bio on success, NULL on failure.
  */
-struct bio *bio_kmalloc(gfp_t gfp_mask, unsigned short nr_iovecs)
+struct bio *bio_kmalloc(unsigned short nr_vecs, gfp_t gfp_mask)
 {
 	struct bio *bio;
 
-	if (nr_iovecs > UIO_MAXIOV)
+	if (nr_vecs > UIO_MAXIOV)
 		return NULL;
-
-	bio = kmalloc(struct_size(bio, bi_inline_vecs, nr_iovecs), gfp_mask);
-	if (unlikely(!bio))
-		return NULL;
-	bio_init(bio, NULL, nr_iovecs ? bio->bi_inline_vecs : NULL, nr_iovecs,
-		 0);
-	bio->bi_pool = NULL;
-	return bio;
+	return kmalloc(struct_size(bio, bi_inline_vecs, nr_vecs), gfp_mask);
 }
 EXPORT_SYMBOL(bio_kmalloc);
 
diff --git a/block/blk-crypto-fallback.c b/block/blk-crypto-fallback.c
index 7c854584b52b..5d1aa5b1d30a 100644
--- a/block/blk-crypto-fallback.c
+++ b/block/blk-crypto-fallback.c
@@ -152,23 +152,25 @@ static void blk_crypto_fallback_encrypt_endio(struct bio *enc_bio)
 
 	src_bio->bi_status = enc_bio->bi_status;
 
-	bio_put(enc_bio);
+	bio_uninit(enc_bio);
+	kfree(enc_bio);
 	bio_endio(src_bio);
 }
 
 static struct bio *blk_crypto_fallback_clone_bio(struct bio *bio_src)
 {
+	unsigned int nr_segs = bio_segments(bio_src);
 	struct bvec_iter iter;
 	struct bio_vec bv;
 	struct bio *bio;
 
-	bio = bio_kmalloc(GFP_NOIO, bio_segments(bio_src));
+	bio = bio_kmalloc(nr_segs, GFP_NOIO);
 	if (!bio)
 		return NULL;
-	bio->bi_bdev		= bio_src->bi_bdev;
+	bio_init(bio, bio_src->bi_bdev, bio->bi_inline_vecs, nr_segs,
+		 bio_src->bi_opf);
 	if (bio_flagged(bio_src, BIO_REMAPPED))
 		bio_set_flag(bio, BIO_REMAPPED);
-	bio->bi_opf		= bio_src->bi_opf;
 	bio->bi_ioprio		= bio_src->bi_ioprio;
 	bio->bi_iter.bi_sector	= bio_src->bi_iter.bi_sector;
 	bio->bi_iter.bi_size	= bio_src->bi_iter.bi_size;
@@ -363,8 +365,8 @@ out_release_keyslot:
 	blk_crypto_put_keyslot(slot);
 out_put_enc_bio:
 	if (enc_bio)
-		bio_put(enc_bio);
-
+		bio_uninit(enc_bio);
+	kfree(enc_bio);
 	return ret;
 }
 
diff --git a/block/blk-map.c b/block/blk-map.c
index c7f71d83eff1..7ffde64f9019 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -152,10 +152,10 @@ static int bio_copy_user_iov(struct request *rq, struct rq_map_data *map_data,
 	nr_pages = bio_max_segs(DIV_ROUND_UP(offset + len, PAGE_SIZE));
 
 	ret = -ENOMEM;
-	bio = bio_kmalloc(gfp_mask, nr_pages);
+	bio = bio_kmalloc(nr_pages, gfp_mask);
 	if (!bio)
 		goto out_bmd;
-	bio->bi_opf |= req_op(rq);
+	bio_init(bio, NULL, bio->bi_inline_vecs, nr_pages, req_op(rq));
 
 	if (map_data) {
 		nr_pages = 1 << map_data->page_order;
@@ -224,7 +224,8 @@ static int bio_copy_user_iov(struct request *rq, struct rq_map_data *map_data,
 cleanup:
 	if (!map_data)
 		bio_free_pages(bio);
-	bio_put(bio);
+	bio_uninit(bio);
+	kfree(bio);
 out_bmd:
 	kfree(bmd);
 	return ret;
@@ -234,6 +235,7 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
 		gfp_t gfp_mask)
 {
 	unsigned int max_sectors = queue_max_hw_sectors(rq->q);
+	unsigned int nr_vecs = iov_iter_npages(iter, BIO_MAX_VECS);
 	struct bio *bio;
 	int ret;
 	int j;
@@ -241,10 +243,10 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
 	if (!iov_iter_count(iter))
 		return -EINVAL;
 
-	bio = bio_kmalloc(gfp_mask, iov_iter_npages(iter, BIO_MAX_VECS));
+	bio = bio_kmalloc(nr_vecs, gfp_mask);
 	if (!bio)
 		return -ENOMEM;
-	bio->bi_opf |= req_op(rq);
+	bio_init(bio, NULL, bio->bi_inline_vecs, nr_vecs, req_op(rq));
 
 	while (iov_iter_count(iter)) {
 		struct page **pages;
@@ -303,7 +305,8 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
 
  out_unmap:
 	bio_release_pages(bio, false);
-	bio_put(bio);
+	bio_uninit(bio);
+	kfree(bio);
 	return ret;
 }
 
@@ -323,7 +326,8 @@ static void bio_invalidate_vmalloc_pages(struct bio *bio)
 static void bio_map_kern_endio(struct bio *bio)
 {
 	bio_invalidate_vmalloc_pages(bio);
-	bio_put(bio);
+	bio_uninit(bio);
+	kfree(bio);
 }
 
 /**
@@ -348,9 +352,10 @@ static struct bio *bio_map_kern(struct request_queue *q, void *data,
 	int offset, i;
 	struct bio *bio;
 
-	bio = bio_kmalloc(gfp_mask, nr_pages);
+	bio = bio_kmalloc(nr_pages, gfp_mask);
 	if (!bio)
 		return ERR_PTR(-ENOMEM);
+	bio_init(bio, NULL, bio->bi_inline_vecs, nr_pages, 0);
 
 	if (is_vmalloc) {
 		flush_kernel_vmap_range(data, len);
@@ -374,7 +379,8 @@ static struct bio *bio_map_kern(struct request_queue *q, void *data,
 		if (bio_add_pc_page(q, bio, page, bytes,
 				    offset) < bytes) {
 			/* we don't support partial mappings */
-			bio_put(bio);
+			bio_uninit(bio);
+			kfree(bio);
 			return ERR_PTR(-EINVAL);
 		}
 
@@ -390,7 +396,8 @@ static struct bio *bio_map_kern(struct request_queue *q, void *data,
 static void bio_copy_kern_endio(struct bio *bio)
 {
 	bio_free_pages(bio);
-	bio_put(bio);
+	bio_uninit(bio);
+	kfree(bio);
 }
 
 static void bio_copy_kern_endio_read(struct bio *bio)
@@ -435,9 +442,10 @@ static struct bio *bio_copy_kern(struct request_queue *q, void *data,
 		return ERR_PTR(-EINVAL);
 
 	nr_pages = end - start;
-	bio = bio_kmalloc(gfp_mask, nr_pages);
+	bio = bio_kmalloc(nr_pages, gfp_mask);
 	if (!bio)
 		return ERR_PTR(-ENOMEM);
+	bio_init(bio, NULL, bio->bi_inline_vecs, nr_pages, 0);
 
 	while (len) {
 		struct page *page;
@@ -471,7 +479,8 @@ static struct bio *bio_copy_kern(struct request_queue *q, void *data,
 
 cleanup:
 	bio_free_pages(bio);
-	bio_put(bio);
+	bio_uninit(bio);
+	kfree(bio);
 	return ERR_PTR(-ENOMEM);
 }
 
@@ -602,7 +611,8 @@ int blk_rq_unmap_user(struct bio *bio)
 
 		next_bio = bio;
 		bio = bio->bi_next;
-		bio_put(next_bio);
+		bio_uninit(next_bio);
+		kfree(next_bio);
 	}
 
 	return ret;
@@ -648,8 +658,10 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
 	bio->bi_opf |= req_op(rq);
 
 	ret = blk_rq_append_bio(rq, bio);
-	if (unlikely(ret))
-		bio_put(bio);
+	if (unlikely(ret)) {
+		bio_uninit(bio);
+		kfree(bio);
+	}
 	return ret;
 }
 EXPORT_SYMBOL(blk_rq_map_kern);