blk: replace bioset_create_nobvec() with a flags arg to bioset_create()

"flags" arguments are often seen as good API design as they allow
easy extensibility.
bioset_create_nobvec() is implemented internally as a variation in
flags passed to __bioset_create().

To support future extension, make the internal structure part of the
API.
i.e. add a 'flags' argument to bioset_create() and discard
bioset_create_nobvec().

Note that the bio_split allocations in drivers/md/raid* do not need
the bvec mempool - they should have used bioset_create_nobvec().

Suggested-by: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/bio.c

@@ -1921,9 +1921,26 @@ void bioset_free(struct bio_set *bs)
 }
 EXPORT_SYMBOL(bioset_free);
 
-static struct bio_set *__bioset_create(unsigned int pool_size,
-				       unsigned int front_pad,
-				       bool create_bvec_pool)
+/**
+ * bioset_create  - Create a bio_set
+ * @pool_size:	Number of bio and bio_vecs to cache in the mempool
+ * @front_pad:	Number of bytes to allocate in front of the returned bio
+ * @flags:	Flags to modify behavior, currently only %BIOSET_NEED_BVECS
+ *
+ * Description:
+ *    Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller
+ *    to ask for a number of bytes to be allocated in front of the bio.
+ *    Front pad allocation is useful for embedding the bio inside
+ *    another structure, to avoid allocating extra data to go with the bio.
+ *    Note that the bio must be embedded at the END of that structure always,
+ *    or things will break badly.
+ *    If %BIOSET_NEED_BVECS is set in @flags, a separate pool will be allocated
+ *    for allocating iovecs.  This pool is not needed e.g. for bio_clone_fast().
+ *
+ */
+struct bio_set *bioset_create(unsigned int pool_size,
+			      unsigned int front_pad,
+			      int flags)
 {
 	unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
 	struct bio_set *bs;
@@ -1948,7 +1965,7 @@ static struct bio_set *__bioset_create(unsigned int pool_size,
 	if (!bs->bio_pool)
 		goto bad;
 
-	if (create_bvec_pool) {
+	if (flags & BIOSET_NEED_BVECS) {
 		bs->bvec_pool = biovec_create_pool(pool_size);
 		if (!bs->bvec_pool)
 			goto bad;
@@ -1963,41 +1980,8 @@ bad:
 	bioset_free(bs);
 	return NULL;
 }
-
-/**
- * bioset_create  - Create a bio_set
- * @pool_size:	Number of bio and bio_vecs to cache in the mempool
- * @front_pad:	Number of bytes to allocate in front of the returned bio
- *
- * Description:
- *    Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller
- *    to ask for a number of bytes to be allocated in front of the bio.
- *    Front pad allocation is useful for embedding the bio inside
- *    another structure, to avoid allocating extra data to go with the bio.
- *    Note that the bio must be embedded at the END of that structure always,
- *    or things will break badly.
- */
-struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad)
-{
-	return __bioset_create(pool_size, front_pad, true);
-}
 EXPORT_SYMBOL(bioset_create);
 
-/**
- * bioset_create_nobvec  - Create a bio_set without bio_vec mempool
- * @pool_size:	Number of bio to cache in the mempool
- * @front_pad:	Number of bytes to allocate in front of the returned bio
- *
- * Description:
- *    Same functionality as bioset_create() except that mempool is not
- *    created for bio_vecs. Saving some memory for bio_clone_fast() users.
- */
-struct bio_set *bioset_create_nobvec(unsigned int pool_size, unsigned int front_pad)
-{
-	return __bioset_create(pool_size, front_pad, false);
-}
-EXPORT_SYMBOL(bioset_create_nobvec);
-
 #ifdef CONFIG_BLK_CGROUP
 
 /**
@@ -2112,7 +2096,7 @@ static int __init init_bio(void)
 	bio_integrity_init();
 	biovec_init_slabs();
 
-	fs_bio_set = bioset_create(BIO_POOL_SIZE, 0);
+	fs_bio_set = bioset_create(BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
 	if (!fs_bio_set)
 		panic("bio: can't allocate bios\n");
 

block/blk-core.c

@@ -790,7 +790,7 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
 	if (q->id < 0)
 		goto fail_q;
 
-	q->bio_split = bioset_create(BIO_POOL_SIZE, 0);
+	q->bio_split = bioset_create(BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
 	if (!q->bio_split)
 		goto fail_id;
 

drivers/block/drbd/drbd_main.c

@@ -2165,7 +2165,7 @@ static int drbd_create_mempools(void)
 		goto Enomem;
 
 	/* mempools */
-	drbd_md_io_bio_set = bioset_create(DRBD_MIN_POOL_PAGES, 0);
+	drbd_md_io_bio_set = bioset_create(DRBD_MIN_POOL_PAGES, 0, BIOSET_NEED_BVECS);
 	if (drbd_md_io_bio_set == NULL)
 		goto Enomem;
 

drivers/md/bcache/super.c

@@ -782,7 +782,7 @@ static int bcache_device_init(struct bcache_device *d, unsigned block_size,
 
 	minor *= BCACHE_MINORS;
 
-	if (!(d->bio_split = bioset_create(4, offsetof(struct bbio, bio))) ||
+	if (!(d->bio_split = bioset_create(4, offsetof(struct bbio, bio), BIOSET_NEED_BVECS)) ||
 	    !(d->disk = alloc_disk(BCACHE_MINORS))) {
 		ida_simple_remove(&bcache_minor, minor);
 		return -ENOMEM;
@@ -1516,7 +1516,7 @@ struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
 				sizeof(struct bbio) + sizeof(struct bio_vec) *
 				bucket_pages(c))) ||
 	    !(c->fill_iter = mempool_create_kmalloc_pool(1, iter_size)) ||
-	    !(c->bio_split = bioset_create(4, offsetof(struct bbio, bio))) ||
+	    !(c->bio_split = bioset_create(4, offsetof(struct bbio, bio), BIOSET_NEED_BVECS)) ||
 	    !(c->uuids = alloc_bucket_pages(GFP_KERNEL, c)) ||
 	    !(c->moving_gc_wq = alloc_workqueue("bcache_gc",
 						WQ_MEM_RECLAIM, 0)) ||

drivers/md/dm-crypt.c

@@ -2677,7 +2677,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 		goto bad;
 	}
 
-	cc->bs = bioset_create(MIN_IOS, 0);
+	cc->bs = bioset_create(MIN_IOS, 0, BIOSET_NEED_BVECS);
 	if (!cc->bs) {
 		ti->error = "Cannot allocate crypt bioset";
 		goto bad;

drivers/md/dm-io.c

@@ -58,7 +58,7 @@ struct dm_io_client *dm_io_client_create(void)
 	if (!client->pool)
 		goto bad;
 
-	client->bios = bioset_create(min_ios, 0);
+	client->bios = bioset_create(min_ios, 0, BIOSET_NEED_BVECS);
 	if (!client->bios)
 		goto bad;
 

drivers/md/dm.c

@@ -2660,7 +2660,7 @@ struct dm_md_mempools *dm_alloc_md_mempools(struct mapped_device *md, enum dm_qu
 		BUG();
 	}
 
-	pools->bs = bioset_create_nobvec(pool_size, front_pad);
+	pools->bs = bioset_create(pool_size, front_pad, 0);
 	if (!pools->bs)
 		goto out;
 

drivers/md/md.c

@@ -5428,7 +5428,7 @@ int md_run(struct mddev *mddev)
 	}
 
 	if (mddev->bio_set == NULL) {
-		mddev->bio_set = bioset_create(BIO_POOL_SIZE, 0);
+		mddev->bio_set = bioset_create(BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
 		if (!mddev->bio_set)
 			return -ENOMEM;
 	}

drivers/md/raid1.c

@@ -2955,7 +2955,7 @@ static struct r1conf *setup_conf(struct mddev *mddev)
 	if (!conf->r1bio_pool)
 		goto abort;
 
-	conf->bio_split = bioset_create(BIO_POOL_SIZE, 0);
+	conf->bio_split = bioset_create(BIO_POOL_SIZE, 0, 0);
 	if (!conf->bio_split)
 		goto abort;
 

drivers/md/raid10.c

@@ -3552,7 +3552,7 @@ static struct r10conf *setup_conf(struct mddev *mddev)
 	if (!conf->r10bio_pool)
 		goto out;
 
-	conf->bio_split = bioset_create(BIO_POOL_SIZE, 0);
+	conf->bio_split = bioset_create(BIO_POOL_SIZE, 0, 0);
 	if (!conf->bio_split)
 		goto out;
 

drivers/md/raid5-cache.c

@@ -3063,7 +3063,7 @@ int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev)
 	if (!log->io_pool)
 		goto io_pool;
 
-	log->bs = bioset_create(R5L_POOL_SIZE, 0);
+	log->bs = bioset_create(R5L_POOL_SIZE, 0, BIOSET_NEED_BVECS);
 	if (!log->bs)
 		goto io_bs;
 

drivers/md/raid5-ppl.c

@@ -1150,7 +1150,7 @@ int ppl_init_log(struct r5conf *conf)
 		goto err;
 	}
 
-	ppl_conf->bs = bioset_create(conf->raid_disks, 0);
+	ppl_conf->bs = bioset_create(conf->raid_disks, 0, 0);
 	if (!ppl_conf->bs) {
 		ret = -ENOMEM;
 		goto err;

drivers/md/raid5.c

@@ -6943,7 +6943,7 @@ static struct r5conf *setup_conf(struct mddev *mddev)
 			goto abort;
 	}
 
-	conf->bio_split = bioset_create(BIO_POOL_SIZE, 0);
+	conf->bio_split = bioset_create(BIO_POOL_SIZE, 0, 0);
 	if (!conf->bio_split)
 		goto abort;
 	conf->mddev = mddev;

drivers/target/target_core_iblock.c

@@ -93,7 +93,7 @@ static int iblock_configure_device(struct se_device *dev)
 		return -EINVAL;
 	}
 
-	ib_dev->ibd_bio_set = bioset_create(IBLOCK_BIO_POOL_SIZE, 0);
+	ib_dev->ibd_bio_set = bioset_create(IBLOCK_BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
 	if (!ib_dev->ibd_bio_set) {
 		pr_err("IBLOCK: Unable to create bioset\n");
 		goto out;

fs/block_dev.c

@@ -439,7 +439,7 @@ blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
 
 static __init int blkdev_init(void)
 {
-	blkdev_dio_pool = bioset_create(4, offsetof(struct blkdev_dio, bio));
+	blkdev_dio_pool = bioset_create(4, offsetof(struct blkdev_dio, bio), BIOSET_NEED_BVECS);
 	if (!blkdev_dio_pool)
 		return -ENOMEM;
 	return 0;

fs/btrfs/extent_io.c

@@ -174,7 +174,8 @@ int __init extent_io_init(void)
 		goto free_state_cache;
 
 	btrfs_bioset = bioset_create(BIO_POOL_SIZE,
-				     offsetof(struct btrfs_io_bio, bio));
+				     offsetof(struct btrfs_io_bio, bio),
+				     BIOSET_NEED_BVECS);
 	if (!btrfs_bioset)
 		goto free_buffer_cache;
 

fs/xfs/xfs_super.c

@@ -1766,7 +1766,8 @@ STATIC int __init
 xfs_init_zones(void)
 {
 	xfs_ioend_bioset = bioset_create(4 * MAX_BUF_PER_PAGE,
-			offsetof(struct xfs_ioend, io_inline_bio));
+			offsetof(struct xfs_ioend, io_inline_bio),
+			BIOSET_NEED_BVECS);
 	if (!xfs_ioend_bioset)
 		goto out;
 

include/linux/bio.h

@@ -373,8 +373,10 @@ static inline struct bio *bio_next_split(struct bio *bio, int sectors,
 	return bio_split(bio, sectors, gfp, bs);
 }
 
-extern struct bio_set *bioset_create(unsigned int, unsigned int);
-extern struct bio_set *bioset_create_nobvec(unsigned int, unsigned int);
+extern struct bio_set *bioset_create(unsigned int, unsigned int, int flags);
+enum {
+	BIOSET_NEED_BVECS = BIT(0),
+};
 extern void bioset_free(struct bio_set *);
 extern mempool_t *biovec_create_pool(int pool_entries);