passthrough request improvements V3

passthrough request improvements V3

[Christoph Hellwig]

These days we have a lot more users of struct request for driver internal
use than just REQ_TYPE_BLOCK_PC, so let's polish this infrastructure
up a bit.

Changes since V2:
 - really drop zeroing ->cmd from blk_get_request
 - add ACK from Boaz
Changes since V1:
 - keep blk_rq_set_block_pc for now and leave zeroing ->cmd in it

[PATCH 1/7] memstick: don't allow REQ_TYPE_BLOCK_PC requests

[Christoph Hellwig]

There is no code to issue or handle REQ_TYPE_BLOCK_PC request in the
memstick drivers, so remove the bogus conditional.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/memstick/core/ms_block.c    | 3 +--
 drivers/memstick/core/mspro_block.c | 3 +--
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/memstick/core/ms_block.c b/drivers/memstick/core/ms_block.c
index 3cd6815..21cc231 100644
--- a/drivers/memstick/core/ms_block.c
+++ b/drivers/memstick/core/ms_block.c
@@ -2002,8 +2002,7 @@ static int msb_bd_getgeo(struct block_device *bdev,
 
 static int msb_prepare_req(struct request_queue *q, struct request *req)
 {
-	if (req->cmd_type != REQ_TYPE_FS &&
-				req->cmd_type != REQ_TYPE_BLOCK_PC) {
+	if (req->cmd_type != REQ_TYPE_FS) {
 		blk_dump_rq_flags(req, "MS unsupported request");
 		return BLKPREP_KILL;
 	}
diff --git a/drivers/memstick/core/mspro_block.c b/drivers/memstick/core/mspro_block.c
index 0fb27d3..586fb8d 100644
--- a/drivers/memstick/core/mspro_block.c
+++ b/drivers/memstick/core/mspro_block.c
@@ -829,8 +829,7 @@ static void mspro_block_start(struct memstick_dev *card)
 
 static int mspro_block_prepare_req(struct request_queue *q, struct request *req)
 {
-	if (req->cmd_type != REQ_TYPE_FS &&
-	    req->cmd_type != REQ_TYPE_BLOCK_PC) {
+	if (req->cmd_type != REQ_TYPE_FS) {
 		blk_dump_rq_flags(req, "MSPro unsupported request");
 		return BLKPREP_KILL;
 	}
-- 
2.1.4

[PATCH 2/7] virtio_blk: use blk_rq_map_kern

[Christoph Hellwig]

Similar to how SCSI and NVMe prepare passthrough requests.  This avoids
poking into request internals too much.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/block/virtio_blk.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 18e4069..963a130 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -236,25 +236,23 @@ static int virtio_queue_rq(struct blk_mq_hw_ctx *hctx,
 static int virtblk_get_id(struct gendisk *disk, char *id_str)
 {
 	struct virtio_blk *vblk = disk->private_data;
+	struct request_queue *q = vblk->disk->queue;
 	struct request *req;
-	struct bio *bio;
 	int err;
 
-	bio = bio_map_kern(vblk->disk->queue, id_str, VIRTIO_BLK_ID_BYTES,
-			   GFP_KERNEL);
-	if (IS_ERR(bio))
-		return PTR_ERR(bio);
-
-	req = blk_make_request(vblk->disk->queue, bio, GFP_KERNEL);
-	if (IS_ERR(req)) {
-		bio_put(bio);
+	req = blk_get_request(q, READ, GFP_KERNEL);
+	if (IS_ERR(req))
 		return PTR_ERR(req);
-	}
-
+	blk_rq_set_block_pc(req);
 	req->cmd_type = REQ_TYPE_DRV_PRIV;
+
+	err = blk_rq_map_kern(q, req, id_str, VIRTIO_BLK_ID_BYTES, GFP_KERNEL);
+	if (err)
+		goto out;
+
 	err = blk_execute_rq(vblk->disk->queue, vblk->disk, req, false);
+out:
 	blk_put_request(req);
-
 	return err;
 }
 
-- 
2.1.4

[PATCH 3/7] block: ensure bios return from blk_get_request are properly initialized

[Christoph Hellwig]

blk_get_request is used for BLOCK_PC and similar passthrough requests.
Currently we always need to call blk_rq_set_block_pc or an open coded
version of it to allow appending bios using the request mapping helpers
later on, which is a somewhat awkward API.  Instead move the
initialization part of blk_rq_set_block_pc into blk_get_request, so that
we always have a safe to use request.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-core.c           | 12 +++++++-----
 block/blk-mq.c             |  4 ++++
 drivers/block/virtio_blk.c |  1 -
 drivers/nvme/host/core.c   |  4 ----
 4 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index c94c7ad..8416c4a 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1294,10 +1294,15 @@ static struct request *blk_old_get_request(struct request_queue *q, int rw,
 
 	spin_lock_irq(q->queue_lock);
 	rq = get_request(q, rw, 0, NULL, gfp_mask);
-	if (IS_ERR(rq))
+	if (IS_ERR(rq)) {
 		spin_unlock_irq(q->queue_lock);
-	/* q->queue_lock is unlocked at this point */
+		return rq;
+	}
 
+	/* q->queue_lock is unlocked at this point */
+	rq->__data_len = 0;
+	rq->__sector = (sector_t) -1;
+	rq->bio = rq->biotail = NULL;
 	return rq;
 }
 
@@ -1377,9 +1382,6 @@ EXPORT_SYMBOL(blk_make_request);
 void blk_rq_set_block_pc(struct request *rq)
 {
 	rq->cmd_type = REQ_TYPE_BLOCK_PC;
-	rq->__data_len = 0;
-	rq->__sector = (sector_t) -1;
-	rq->bio = rq->biotail = NULL;
 	memset(rq->__cmd, 0, sizeof(rq->__cmd));
 }
 EXPORT_SYMBOL(blk_rq_set_block_pc);
diff --git a/block/blk-mq.c b/block/blk-mq.c
index bc7166d..b5606dc 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -263,6 +263,10 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
 		blk_queue_exit(q);
 		return ERR_PTR(-EWOULDBLOCK);
 	}
+
+	rq->__data_len = 0;
+	rq->__sector = (sector_t) -1;
+	rq->bio = rq->biotail = NULL;
 	return rq;
 }
 EXPORT_SYMBOL(blk_mq_alloc_request);
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 963a130..0be7dd6 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -243,7 +243,6 @@ static int virtblk_get_id(struct gendisk *disk, char *id_str)
 	req = blk_get_request(q, READ, GFP_KERNEL);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
-	blk_rq_set_block_pc(req);
 	req->cmd_type = REQ_TYPE_DRV_PRIV;
 
 	err = blk_rq_map_kern(q, req, id_str, VIRTIO_BLK_ID_BYTES, GFP_KERNEL);
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 9d7cee4..cb8ca1b 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -201,10 +201,6 @@ struct request *nvme_alloc_request(struct request_queue *q,
 
 	req->cmd_type = REQ_TYPE_DRV_PRIV;
 	req->cmd_flags |= REQ_FAILFAST_DRIVER;
-	req->__data_len = 0;
-	req->__sector = (sector_t) -1;
-	req->bio = req->biotail = NULL;
-
 	req->cmd = (unsigned char *)cmd;
 	req->cmd_len = sizeof(struct nvme_command);
 
-- 
2.1.4

[PATCH 4/7] block: simplify and export blk_rq_append_bio

[Christoph Hellwig]

The target SCSI passthrough backend is much better served with the low-level
blk_rq_append_bio construct then the helpers built on top of it, so export it.

Also use the opportunity to remove the pointless request_queue argument and
make the code flow a little more readable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-core.c       |  2 +-
 block/blk-map.c        | 25 +++++++++++++++----------
 block/blk.h            |  2 --
 include/linux/blkdev.h |  1 +
 4 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 8416c4a..1952c52 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1363,7 +1363,7 @@ struct request *blk_make_request(struct request_queue *q, struct bio *bio,
 		int ret;
 
 		blk_queue_bounce(q, &bounce_bio);
-		ret = blk_rq_append_bio(q, rq, bounce_bio);
+		ret = blk_rq_append_bio(rq, bounce_bio);
 		if (unlikely(ret)) {
 			blk_put_request(rq);
 			return ERR_PTR(ret);
diff --git a/block/blk-map.c b/block/blk-map.c
index 61733a6..b8657fa 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -9,21 +9,26 @@
 
 #include "blk.h"
 
-int blk_rq_append_bio(struct request_queue *q, struct request *rq,
-		      struct bio *bio)
+/*
+ * Append a bio to a passthrough request.  Only works can be merged into
+ * the request based on the driver constraints.
+ */
+int blk_rq_append_bio(struct request *rq, struct bio *bio)
 {
-	if (!rq->bio)
-		blk_rq_bio_prep(q, rq, bio);
-	else if (!ll_back_merge_fn(q, rq, bio))
-		return -EINVAL;
-	else {
+	if (!rq->bio) {
+		blk_rq_bio_prep(rq->q, rq, bio);
+	} else {
+		if (!ll_back_merge_fn(rq->q, rq, bio))
+			return -EINVAL;
+
 		rq->biotail->bi_next = bio;
 		rq->biotail = bio;
-
 		rq->__data_len += bio->bi_iter.bi_size;
 	}
+
 	return 0;
 }
+EXPORT_SYMBOL(blk_rq_append_bio);
 
 static int __blk_rq_unmap_user(struct bio *bio)
 {
@@ -71,7 +76,7 @@ static int __blk_rq_map_user_iov(struct request *rq,
 	 */
 	bio_get(bio);
 
-	ret = blk_rq_append_bio(q, rq, bio);
+	ret = blk_rq_append_bio(rq, bio);
 	if (ret) {
 		bio_endio(bio);
 		__blk_rq_unmap_user(orig_bio);
@@ -229,7 +234,7 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
 	if (do_copy)
 		rq->cmd_flags |= REQ_COPY_USER;
 
-	ret = blk_rq_append_bio(q, rq, bio);
+	ret = blk_rq_append_bio(rq, bio);
 	if (unlikely(ret)) {
 		/* request is too big */
 		bio_put(bio);
diff --git a/block/blk.h b/block/blk.h
index 70e4aee..c37492f 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -64,8 +64,6 @@ void blk_exit_rl(struct request_list *rl);
 void init_request_from_bio(struct request *req, struct bio *bio);
 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
 			struct bio *bio);
-int blk_rq_append_bio(struct request_queue *q, struct request *rq,
-		      struct bio *bio);
 void blk_queue_bypass_start(struct request_queue *q);
 void blk_queue_bypass_end(struct request_queue *q);
 void blk_dequeue_request(struct request *rq);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 9d1e0a4..07176f4 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -801,6 +801,7 @@ extern int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
 extern void blk_rq_unprep_clone(struct request *rq);
 extern int blk_insert_cloned_request(struct request_queue *q,
 				     struct request *rq);
+extern int blk_rq_append_bio(struct request *rq, struct bio *bio);
 extern void blk_delay_queue(struct request_queue *, unsigned long);
 extern void blk_queue_split(struct request_queue *, struct bio **,
 			    struct bio_set *);
-- 
2.1.4

[PATCH 5/7] target: stop using blk_make_request

[Christoph Hellwig]

Using blk_rq_append_bio allows to append the bios to the request
directly instead of having to build up a list first, and also
allows to have a single code path for requests with or without
data attached to them.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/target/target_core_pscsi.c | 87 +++++++++++++++-----------------------
 1 file changed, 34 insertions(+), 53 deletions(-)

diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
index 81564c8..9125d93 100644
--- a/drivers/target/target_core_pscsi.c
+++ b/drivers/target/target_core_pscsi.c
@@ -876,19 +876,19 @@ static inline struct bio *pscsi_get_bio(int nr_vecs)
 
 static sense_reason_t
 pscsi_map_sg(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
-		enum dma_data_direction data_direction, struct bio **hbio)
+		struct request *req)
 {
 	struct pscsi_dev_virt *pdv = PSCSI_DEV(cmd->se_dev);
-	struct bio *bio = NULL, *tbio = NULL;
+	struct bio *bio = NULL;
 	struct page *page;
 	struct scatterlist *sg;
 	u32 data_len = cmd->data_length, i, len, bytes, off;
 	int nr_pages = (cmd->data_length + sgl[0].offset +
 			PAGE_SIZE - 1) >> PAGE_SHIFT;
 	int nr_vecs = 0, rc;
-	int rw = (data_direction == DMA_TO_DEVICE);
+	int rw = (cmd->data_direction == DMA_TO_DEVICE);
 
-	*hbio = NULL;
+	BUG_ON(!cmd->data_length);
 
 	pr_debug("PSCSI: nr_pages: %d\n", nr_pages);
 
@@ -927,16 +927,6 @@ pscsi_map_sg(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
 				pr_debug("PSCSI: Allocated bio: %p,"
 					" dir: %s nr_vecs: %d\n", bio,
 					(rw) ? "rw" : "r", nr_vecs);
-				/*
-				 * Set *hbio pointer to handle the case:
-				 * nr_pages > BIO_MAX_PAGES, where additional
-				 * bios need to be added to complete a given
-				 * command.
-				 */
-				if (!*hbio)
-					*hbio = tbio = bio;
-				else
-					tbio = tbio->bi_next = bio;
 			}
 
 			pr_debug("PSCSI: Calling bio_add_pc_page() i: %d"
@@ -955,11 +945,16 @@ pscsi_map_sg(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
 				pr_debug("PSCSI: Reached bio->bi_vcnt max:"
 					" %d i: %d bio: %p, allocating another"
 					" bio\n", bio->bi_vcnt, i, bio);
+
+				rc = blk_rq_append_bio(req, bio);
+				if (rc) {
+					pr_err("pSCSI: failed to append bio\n");
+					goto fail;
+				}
+
 				/*
 				 * Clear the pointer so that another bio will
-				 * be allocated with pscsi_get_bio() above, the
-				 * current bio has already been set *tbio and
-				 * bio->bi_next.
+				 * be allocated with pscsi_get_bio() above.
 				 */
 				bio = NULL;
 			}
@@ -968,13 +963,16 @@ pscsi_map_sg(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
 		}
 	}
 
+	if (bio) {
+		rc = blk_rq_append_bio(req, bio);
+		if (rc) {
+			pr_err("pSCSI: failed to append bio\n");
+			goto fail;
+		}
+	}
+
 	return 0;
 fail:
-	while (*hbio) {
-		bio = *hbio;
-		*hbio = (*hbio)->bi_next;
-		bio_endio(bio);
-	}
 	return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 }
 
@@ -992,11 +990,9 @@ pscsi_execute_cmd(struct se_cmd *cmd)
 {
 	struct scatterlist *sgl = cmd->t_data_sg;
 	u32 sgl_nents = cmd->t_data_nents;
-	enum dma_data_direction data_direction = cmd->data_direction;
 	struct pscsi_dev_virt *pdv = PSCSI_DEV(cmd->se_dev);
 	struct pscsi_plugin_task *pt;
 	struct request *req;
-	struct bio *hbio;
 	sense_reason_t ret;
 
 	/*
@@ -1012,31 +1008,21 @@ pscsi_execute_cmd(struct se_cmd *cmd)
 	memcpy(pt->pscsi_cdb, cmd->t_task_cdb,
 		scsi_command_size(cmd->t_task_cdb));
 
-	if (!sgl) {
-		req = blk_get_request(pdv->pdv_sd->request_queue,
-				(data_direction == DMA_TO_DEVICE),
-				GFP_KERNEL);
-		if (IS_ERR(req)) {
-			pr_err("PSCSI: blk_get_request() failed\n");
-			ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
-			goto fail;
-		}
+	req = blk_get_request(pdv->pdv_sd->request_queue,
+			(cmd->data_direction == DMA_TO_DEVICE),
+			GFP_KERNEL);
+	if (IS_ERR(req)) {
+		pr_err("PSCSI: blk_get_request() failed\n");
+		ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+		goto fail;
+	}
 
-		blk_rq_set_block_pc(req);
-	} else {
-		BUG_ON(!cmd->data_length);
+	blk_rq_set_block_pc(req);
 
-		ret = pscsi_map_sg(cmd, sgl, sgl_nents, data_direction, &hbio);
+	if (sgl) {
+		ret = pscsi_map_sg(cmd, sgl, sgl_nents, req);
 		if (ret)
-			goto fail;
-
-		req = blk_make_request(pdv->pdv_sd->request_queue, hbio,
-				       GFP_KERNEL);
-		if (IS_ERR(req)) {
-			pr_err("pSCSI: blk_make_request() failed\n");
-			ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
-			goto fail_free_bio;
-		}
+			goto fail_put_request;
 	}
 
 	req->end_io = pscsi_req_done;
@@ -1057,13 +1043,8 @@ pscsi_execute_cmd(struct se_cmd *cmd)
 
 	return 0;
 
-fail_free_bio:
-	while (hbio) {
-		struct bio *bio = hbio;
-		hbio = hbio->bi_next;
-		bio_endio(bio);
-	}
-	ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+fail_put_request:
+	blk_put_request(req);
 fail:
 	kfree(pt);
 	return ret;
-- 
2.1.4

[PATCH 6/7] scsi/osd: open code blk_make_request

[Christoph Hellwig]

I wish the OSD code could simply use blk_rq_map_* helpers like
everyone else, but the complex nature of deciding if we have
DATA IN and/or DATA OUT buffers might make this impossible
(at least for a mere human like me).

But using blk_rq_append_bio at least allows sharing the setup code
between request with or without dat a buffers, and given that this
is the last user of blk_make_request it allows getting rid of that
somewhat awkward interface.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Boaz Harrosh <ooo@electrozaur.com>
---
 block/blk-core.c                 | 57 ----------------------------------------
 drivers/scsi/osd/osd_initiator.c | 25 +++++++++++-------
 include/linux/blkdev.h           |  2 --
 3 files changed, 16 insertions(+), 68 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 1952c52..85fdb99 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1318,63 +1318,6 @@ struct request *blk_get_request(struct request_queue *q, int rw, gfp_t gfp_mask)
 EXPORT_SYMBOL(blk_get_request);
 
 /**
- * blk_make_request - given a bio, allocate a corresponding struct request.
- * @q: target request queue
- * @bio:  The bio describing the memory mappings that will be submitted for IO.
- *        It may be a chained-bio properly constructed by block/bio layer.
- * @gfp_mask: gfp flags to be used for memory allocation
- *
- * blk_make_request is the parallel of generic_make_request for BLOCK_PC
- * type commands. Where the struct request needs to be farther initialized by
- * the caller. It is passed a &struct bio, which describes the memory info of
- * the I/O transfer.
- *
- * The caller of blk_make_request must make sure that bi_io_vec
- * are set to describe the memory buffers. That bio_data_dir() will return
- * the needed direction of the request. (And all bio's in the passed bio-chain
- * are properly set accordingly)
- *
- * If called under none-sleepable conditions, mapped bio buffers must not
- * need bouncing, by calling the appropriate masked or flagged allocator,
- * suitable for the target device. Otherwise the call to blk_queue_bounce will
- * BUG.
- *
- * WARNING: When allocating/cloning a bio-chain, careful consideration should be
- * given to how you allocate bios. In particular, you cannot use
- * __GFP_DIRECT_RECLAIM for anything but the first bio in the chain. Otherwise
- * you risk waiting for IO completion of a bio that hasn't been submitted yet,
- * thus resulting in a deadlock. Alternatively bios should be allocated using
- * bio_kmalloc() instead of bio_alloc(), as that avoids the mempool deadlock.
- * If possible a big IO should be split into smaller parts when allocation
- * fails. Partial allocation should not be an error, or you risk a live-lock.
- */
-struct request *blk_make_request(struct request_queue *q, struct bio *bio,
-				 gfp_t gfp_mask)
-{
-	struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask);
-
-	if (IS_ERR(rq))
-		return rq;
-
-	blk_rq_set_block_pc(rq);
-
-	for_each_bio(bio) {
-		struct bio *bounce_bio = bio;
-		int ret;
-
-		blk_queue_bounce(q, &bounce_bio);
-		ret = blk_rq_append_bio(rq, bounce_bio);
-		if (unlikely(ret)) {
-			blk_put_request(rq);
-			return ERR_PTR(ret);
-		}
-	}
-
-	return rq;
-}
-EXPORT_SYMBOL(blk_make_request);
-
-/**
  * blk_rq_set_block_pc - initialize a request to type BLOCK_PC
  * @rq:		request to be initialized
  *
diff --git a/drivers/scsi/osd/osd_initiator.c b/drivers/scsi/osd/osd_initiator.c
index daa4dc1..2f2a991 100644
--- a/drivers/scsi/osd/osd_initiator.c
+++ b/drivers/scsi/osd/osd_initiator.c
@@ -1558,18 +1558,25 @@ static int _osd_req_finalize_data_integrity(struct osd_request *or,
 static struct request *_make_request(struct request_queue *q, bool has_write,
 			      struct _osd_io_info *oii, gfp_t flags)
 {
-	if (oii->bio)
-		return blk_make_request(q, oii->bio, flags);
-	else {
-		struct request *req;
-
-		req = blk_get_request(q, has_write ? WRITE : READ, flags);
-		if (IS_ERR(req))
-			return req;
+	struct request *req;
+	struct bio *bio = oii->bio;
+	int ret;
 
-		blk_rq_set_block_pc(req);
+	req = blk_get_request(q, has_write ? WRITE : READ, flags);
+	if (IS_ERR(req))
 		return req;
+	blk_rq_set_block_pc(req);
+
+	for_each_bio(bio) {
+		struct bio *bounce_bio = bio;
+
+		blk_queue_bounce(req->q, &bounce_bio);
+		ret = blk_rq_append_bio(req, bounce_bio);
+		if (ret)
+			return ERR_PTR(ret);
 	}
+
+	return req;
 }
 
 static int _init_blk_request(struct osd_request *or,
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 07176f4..3be95eb 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -787,8 +787,6 @@ extern void blk_rq_init(struct request_queue *q, struct request *rq);
 extern void blk_put_request(struct request *);
 extern void __blk_put_request(struct request_queue *, struct request *);
 extern struct request *blk_get_request(struct request_queue *, int, gfp_t);
-extern struct request *blk_make_request(struct request_queue *, struct bio *,
-					gfp_t);
 extern void blk_rq_set_block_pc(struct request *);
 extern void blk_requeue_request(struct request_queue *, struct request *);
 extern void blk_add_request_payload(struct request *rq, struct page *page,
-- 
2.1.4

[PATCH 7/7] block: unexport various bio mapping helpers

[Christoph Hellwig]

They are unused and potential new users really should use the
blk_rq_map* versions.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/bio.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 848cd35..b88ed1c 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1097,7 +1097,6 @@ int bio_uncopy_user(struct bio *bio)
 	bio_put(bio);
 	return ret;
 }
-EXPORT_SYMBOL(bio_uncopy_user);
 
 /**
  *	bio_copy_user_iov	-	copy user data to bio
@@ -1392,7 +1391,6 @@ void bio_unmap_user(struct bio *bio)
 	__bio_unmap_user(bio);
 	bio_put(bio);
 }
-EXPORT_SYMBOL(bio_unmap_user);
 
 static void bio_map_kern_endio(struct bio *bio)
 {
@@ -1538,7 +1536,6 @@ cleanup:
 	bio_put(bio);
 	return ERR_PTR(-ENOMEM);
 }
-EXPORT_SYMBOL(bio_copy_kern);
 
 /*
  * bio_set_pages_dirty() and bio_check_pages_dirty() are support functions
-- 
2.1.4

Re: passthrough request improvements V3

[Christoph Hellwig]

ping?  Seems like you were mostly happy with the previous versions,
and I should have addressed all comments.

On Thu, Jun 16, 2016 at 11:14:24AM +0200, Christoph Hellwig wrote:
> These days we have a lot more users of struct request for driver internal
> use than just REQ_TYPE_BLOCK_PC, so let's polish this infrastructure
> up a bit.
> 
> Changes since V2:
>  - really drop zeroing ->cmd from blk_get_request
>  - add ACK from Boaz
> Changes since V1:
>  - keep blk_rq_set_block_pc for now and leave zeroing ->cmd in it
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-block" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
---end quoted text---

[PATCH 4/7] block: simplify and export blk_rq_append_bio

[Christoph Hellwig]

The target SCSI passthrough backend is much better served with the low-level
blk_rq_append_bio construct then the helpers built on top of it, so export it.

Also use the opportunity to remove the pointless request_queue argument and
make the code flow a little more readable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-core.c       |  2 +-
 block/blk-map.c        | 25 +++++++++++++++----------
 block/blk.h            |  2 --
 include/linux/blkdev.h |  1 +
 4 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 3d22fa2..0e8b00f 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1363,7 +1363,7 @@ struct request *blk_make_request(struct request_queue *q, struct bio *bio,
 		int ret;
 
 		blk_queue_bounce(q, &bounce_bio);
-		ret = blk_rq_append_bio(q, rq, bounce_bio);
+		ret = blk_rq_append_bio(rq, bounce_bio);
 		if (unlikely(ret)) {
 			blk_put_request(rq);
 			return ERR_PTR(ret);
diff --git a/block/blk-map.c b/block/blk-map.c
index 61733a6..b8657fa 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -9,21 +9,26 @@
 
 #include "blk.h"
 
-int blk_rq_append_bio(struct request_queue *q, struct request *rq,
-		      struct bio *bio)
+/*
+ * Append a bio to a passthrough request.  Only works can be merged into
+ * the request based on the driver constraints.
+ */
+int blk_rq_append_bio(struct request *rq, struct bio *bio)
 {
-	if (!rq->bio)
-		blk_rq_bio_prep(q, rq, bio);
-	else if (!ll_back_merge_fn(q, rq, bio))
-		return -EINVAL;
-	else {
+	if (!rq->bio) {
+		blk_rq_bio_prep(rq->q, rq, bio);
+	} else {
+		if (!ll_back_merge_fn(rq->q, rq, bio))
+			return -EINVAL;
+
 		rq->biotail->bi_next = bio;
 		rq->biotail = bio;
-
 		rq->__data_len += bio->bi_iter.bi_size;
 	}
+
 	return 0;
 }
+EXPORT_SYMBOL(blk_rq_append_bio);
 
 static int __blk_rq_unmap_user(struct bio *bio)
 {
@@ -71,7 +76,7 @@ static int __blk_rq_map_user_iov(struct request *rq,
 	 */
 	bio_get(bio);
 
-	ret = blk_rq_append_bio(q, rq, bio);
+	ret = blk_rq_append_bio(rq, bio);
 	if (ret) {
 		bio_endio(bio);
 		__blk_rq_unmap_user(orig_bio);
@@ -229,7 +234,7 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
 	if (do_copy)
 		rq->cmd_flags |= REQ_COPY_USER;
 
-	ret = blk_rq_append_bio(q, rq, bio);
+	ret = blk_rq_append_bio(rq, bio);
 	if (unlikely(ret)) {
 		/* request is too big */
 		bio_put(bio);
diff --git a/block/blk.h b/block/blk.h
index 70e4aee..c37492f 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -64,8 +64,6 @@ void blk_exit_rl(struct request_list *rl);
 void init_request_from_bio(struct request *req, struct bio *bio);
 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
 			struct bio *bio);
-int blk_rq_append_bio(struct request_queue *q, struct request *rq,
-		      struct bio *bio);
 void blk_queue_bypass_start(struct request_queue *q);
 void blk_queue_bypass_end(struct request_queue *q);
 void blk_dequeue_request(struct request *rq);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 9ae49cc..a029ad9 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -801,6 +801,7 @@ extern int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
 extern void blk_rq_unprep_clone(struct request *rq);
 extern int blk_insert_cloned_request(struct request_queue *q,
 				     struct request *rq);
+extern int blk_rq_append_bio(struct request *rq, struct bio *bio);
 extern void blk_delay_queue(struct request_queue *, unsigned long);
 extern void blk_queue_split(struct request_queue *, struct bio **,
 			    struct bio_set *);
-- 
2.1.4

[PATCH 4/7] block: simplify and export blk_rq_append_bio

[Christoph Hellwig]

The target SCSI passthrough backend is much better served with the low-level
blk_rq_append_bio construct then the helpers built on top of it, so export it.

Also use the opportunity to remove the pointless request_queue argument and
make the code flow a little more readable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-core.c       |  2 +-
 block/blk-map.c        | 25 +++++++++++++++----------
 block/blk.h            |  2 --
 include/linux/blkdev.h |  1 +
 4 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 37852ec..2c4c021 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1364,7 +1364,7 @@ struct request *blk_make_request(struct request_queue *q, struct bio *bio,
 		int ret;
 
 		blk_queue_bounce(q, &bounce_bio);
-		ret = blk_rq_append_bio(q, rq, bounce_bio);
+		ret = blk_rq_append_bio(rq, bounce_bio);
 		if (unlikely(ret)) {
 			blk_put_request(rq);
 			return ERR_PTR(ret);
diff --git a/block/blk-map.c b/block/blk-map.c
index 61733a6..b8657fa 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -9,21 +9,26 @@
 
 #include "blk.h"
 
-int blk_rq_append_bio(struct request_queue *q, struct request *rq,
-		      struct bio *bio)
+/*
+ * Append a bio to a passthrough request.  Only works can be merged into
+ * the request based on the driver constraints.
+ */
+int blk_rq_append_bio(struct request *rq, struct bio *bio)
 {
-	if (!rq->bio)
-		blk_rq_bio_prep(q, rq, bio);
-	else if (!ll_back_merge_fn(q, rq, bio))
-		return -EINVAL;
-	else {
+	if (!rq->bio) {
+		blk_rq_bio_prep(rq->q, rq, bio);
+	} else {
+		if (!ll_back_merge_fn(rq->q, rq, bio))
+			return -EINVAL;
+
 		rq->biotail->bi_next = bio;
 		rq->biotail = bio;
-
 		rq->__data_len += bio->bi_iter.bi_size;
 	}
+
 	return 0;
 }
+EXPORT_SYMBOL(blk_rq_append_bio);
 
 static int __blk_rq_unmap_user(struct bio *bio)
 {
@@ -71,7 +76,7 @@ static int __blk_rq_map_user_iov(struct request *rq,
 	 */
 	bio_get(bio);
 
-	ret = blk_rq_append_bio(q, rq, bio);
+	ret = blk_rq_append_bio(rq, bio);
 	if (ret) {
 		bio_endio(bio);
 		__blk_rq_unmap_user(orig_bio);
@@ -229,7 +234,7 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
 	if (do_copy)
 		rq->cmd_flags |= REQ_COPY_USER;
 
-	ret = blk_rq_append_bio(q, rq, bio);
+	ret = blk_rq_append_bio(rq, bio);
 	if (unlikely(ret)) {
 		/* request is too big */
 		bio_put(bio);
diff --git a/block/blk.h b/block/blk.h
index 70e4aee..c37492f 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -64,8 +64,6 @@ void blk_exit_rl(struct request_list *rl);
 void init_request_from_bio(struct request *req, struct bio *bio);
 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
 			struct bio *bio);
-int blk_rq_append_bio(struct request_queue *q, struct request *rq,
-		      struct bio *bio);
 void blk_queue_bypass_start(struct request_queue *q);
 void blk_queue_bypass_end(struct request_queue *q);
 void blk_dequeue_request(struct request *rq);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 9d1e0a4..07176f4 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -801,6 +801,7 @@ extern int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
 extern void blk_rq_unprep_clone(struct request *rq);
 extern int blk_insert_cloned_request(struct request_queue *q,
 				     struct request *rq);
+extern int blk_rq_append_bio(struct request *rq, struct bio *bio);
 extern void blk_delay_queue(struct request_queue *, unsigned long);
 extern void blk_queue_split(struct request_queue *, struct bio **,
 			    struct bio_set *);
-- 
2.1.4

[PATCH 4/7] block: simplify and export blk_rq_append_bio

[Christoph Hellwig]

The target SCSI passthrough backend is much better served with the low-level
blk_rq_append_bio construct then the helpers built on top of it, so export it.

Also use the opportunity to remove the pointless request_queue argument and
make the code flow a little more readable.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/blk-core.c       |  2 +-
 block/blk-map.c        | 25 +++++++++++++++----------
 block/blk.h            |  2 --
 include/linux/blkdev.h |  1 +
 4 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/block/blk-core.c b/block/blk-core.c
index 2b179cd..ceefa48 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1364,7 +1364,7 @@ struct request *blk_make_request(struct request_queue *q, struct bio *bio,
 		int ret;
 
 		blk_queue_bounce(q, &bounce_bio);
-		ret = blk_rq_append_bio(q, rq, bounce_bio);
+		ret = blk_rq_append_bio(rq, bounce_bio);
 		if (unlikely(ret)) {
 			blk_put_request(rq);
 			return ERR_PTR(ret);
diff --git a/block/blk-map.c b/block/blk-map.c
index 61733a6..b8657fa 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -9,21 +9,26 @@
 
 #include "blk.h"
 
-int blk_rq_append_bio(struct request_queue *q, struct request *rq,
-		      struct bio *bio)
+/*
+ * Append a bio to a passthrough request.  Only works can be merged into
+ * the request based on the driver constraints.
+ */
+int blk_rq_append_bio(struct request *rq, struct bio *bio)
 {
-	if (!rq->bio)
-		blk_rq_bio_prep(q, rq, bio);
-	else if (!ll_back_merge_fn(q, rq, bio))
-		return -EINVAL;
-	else {
+	if (!rq->bio) {
+		blk_rq_bio_prep(rq->q, rq, bio);
+	} else {
+		if (!ll_back_merge_fn(rq->q, rq, bio))
+			return -EINVAL;
+
 		rq->biotail->bi_next = bio;
 		rq->biotail = bio;
-
 		rq->__data_len += bio->bi_iter.bi_size;
 	}
+
 	return 0;
 }
+EXPORT_SYMBOL(blk_rq_append_bio);
 
 static int __blk_rq_unmap_user(struct bio *bio)
 {
@@ -71,7 +76,7 @@ static int __blk_rq_map_user_iov(struct request *rq,
 	 */
 	bio_get(bio);
 
-	ret = blk_rq_append_bio(q, rq, bio);
+	ret = blk_rq_append_bio(rq, bio);
 	if (ret) {
 		bio_endio(bio);
 		__blk_rq_unmap_user(orig_bio);
@@ -229,7 +234,7 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf,
 	if (do_copy)
 		rq->cmd_flags |= REQ_COPY_USER;
 
-	ret = blk_rq_append_bio(q, rq, bio);
+	ret = blk_rq_append_bio(rq, bio);
 	if (unlikely(ret)) {
 		/* request is too big */
 		bio_put(bio);
diff --git a/block/blk.h b/block/blk.h
index 70e4aee..c37492f 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -64,8 +64,6 @@ void blk_exit_rl(struct request_list *rl);
 void init_request_from_bio(struct request *req, struct bio *bio);
 void blk_rq_bio_prep(struct request_queue *q, struct request *rq,
 			struct bio *bio);
-int blk_rq_append_bio(struct request_queue *q, struct request *rq,
-		      struct bio *bio);
 void blk_queue_bypass_start(struct request_queue *q);
 void blk_queue_bypass_end(struct request_queue *q);
 void blk_dequeue_request(struct request *rq);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 472b527..998fbe0 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -800,6 +800,7 @@ extern int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
 extern void blk_rq_unprep_clone(struct request *rq);
 extern int blk_insert_cloned_request(struct request_queue *q,
 				     struct request *rq);
+extern int blk_rq_append_bio(struct request *rq, struct bio *bio);
 extern void blk_delay_queue(struct request_queue *, unsigned long);
 extern void blk_queue_split(struct request_queue *, struct bio **,
 			    struct bio_set *);
-- 
2.1.4