[05/10] block, nvme: modify rq_integrity_vec function

Commit Message

Kanchan Joshi April 25, 2024, 6:39 p.m. UTC

rq_integrity_vec always returns the first bio_vec, and does not take
bip_iter into consideration.
Modify it so that it does. This is similar to how req_bvec() works for
data buffers.

This is necessary for correct dma map/unmap of meta buffer when it was
split in the block layer.

Signed-off-by: Anuj Gupta <[e-mail]>
Signed-off-by: Kanchan Joshi <[e-mail]>
---
 drivers/nvme/host/pci.c       |  9 +++++----
 include/linux/blk-integrity.h | 13 +++++++------
 2 files changed, 12 insertions(+), 10 deletions(-)

Comments

Christoph Hellwig April 27, 2024, 7:18 a.m. UTC | #1

The subjet is about as useless as it gets :)

The essence is that it should take the iter into account, so name that.

> --- a/include/linux/blk-integrity.h
> +++ b/include/linux/blk-integrity.h
> @@ -109,11 +109,12 @@ static inline bool blk_integrity_rq(struct request *rq)
>   * Return the first bvec that contains integrity data.  Only drivers that are
>   * limited to a single integrity segment should use this helper.
>   */

The comment really needs an update.  With this rq_integrity_vec now
is a "normal" iter based operation, that can actually be used by
drivers with multiple integrity segments if it is properly advanced.

> +static inline struct bio_vec rq_integrity_vec(struct request *rq)
>  {
> -	return NULL;
> +	return (struct bio_vec){0};

No need for the 0 here.

Kanchan Joshi April 29, 2024, 11:34 a.m. UTC | #2

On 4/27/2024 12:48 PM, Christoph Hellwig wrote:
> The subjet is about as useless as it gets :)
> 
> The essence is that it should take the iter into account, so name that.

Sure.

>> --- a/include/linux/blk-integrity.h
>> +++ b/include/linux/blk-integrity.h
>> @@ -109,11 +109,12 @@ static inline bool blk_integrity_rq(struct request *rq)
>>    * Return the first bvec that contains integrity data.  Only drivers that are
>>    * limited to a single integrity segment should use this helper.
>>    */
> 
> The comment really needs an update.  With this rq_integrity_vec now
> is a "normal" iter based operation, that can actually be used by
> drivers with multiple integrity segments if it is properly advanced.

Right, will update.

>> +static inline struct bio_vec rq_integrity_vec(struct request *rq)
>>   {
>> -	return NULL;
>> +	return (struct bio_vec){0};
> 
> No need for the 0 here.
  Um, I did not follow. Need that to keep the compiler happy.
Do you suggest to change the prototype.

Christoph Hellwig April 29, 2024, 5:11 p.m. UTC | #3

On Mon, Apr 29, 2024 at 05:04:30PM +0530, Kanchan Joshi wrote:
> >> +	return (struct bio_vec){0};
> > 
> > No need for the 0 here.
>   Um, I did not follow. Need that to keep the compiler happy.
> Do you suggest to change the prototype.

Just removing the NULL as in:

	return (struct bio_vec){ };

compiles just fine here, and at least for non-anonymous struct
initializers we use it all the time.

Patch

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 8e0bb9692685..bc5177ea6330 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -825,9 +825,9 @@  static blk_status_t nvme_map_metadata(struct nvme_dev *dev, struct request *req,
 		struct nvme_command *cmnd)
 {
 	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
+	struct bio_vec bv = rq_integrity_vec(req);
 
-	iod->meta_dma = dma_map_bvec(dev->dev, rq_integrity_vec(req),
-			rq_dma_dir(req), 0);
+	iod->meta_dma = dma_map_bvec(dev->dev, &bv, rq_dma_dir(req), 0);
 	if (dma_mapping_error(dev->dev, iod->meta_dma))
 		return BLK_STS_IOERR;
 	cmnd->rw.metadata = cpu_to_le64(iod->meta_dma);
@@ -964,9 +964,10 @@  static __always_inline void nvme_pci_unmap_rq(struct request *req)
 
 	if (blk_integrity_rq(req)) {
 	        struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
+		struct bio_vec bv = rq_integrity_vec(req);
 
-		dma_unmap_page(dev->dev, iod->meta_dma,
-			       rq_integrity_vec(req)->bv_len, rq_dma_dir(req));
+		dma_unmap_page(dev->dev, iod->meta_dma, bv.bv_len,
+			       rq_dma_dir(req));
 	}
 
 	if (blk_rq_nr_phys_segments(req))
diff --git a/include/linux/blk-integrity.h b/include/linux/blk-integrity.h
index e253e7bd0d17..9223050c0f75 100644
--- a/include/linux/blk-integrity.h
+++ b/include/linux/blk-integrity.h
@@ -109,11 +109,12 @@  static inline bool blk_integrity_rq(struct request *rq)
  * Return the first bvec that contains integrity data.  Only drivers that are
  * limited to a single integrity segment should use this helper.
  */
-static inline struct bio_vec *rq_integrity_vec(struct request *rq)
+static inline struct bio_vec rq_integrity_vec(struct request *rq)
 {
-	if (WARN_ON_ONCE(queue_max_integrity_segments(rq->q) > 1))
-		return NULL;
-	return rq->bio->bi_integrity->bip_vec;
+	WARN_ON_ONCE(queue_max_integrity_segments(rq->q) > 1);
+
+	return mp_bvec_iter_bvec(rq->bio->bi_integrity->bip_vec,
+				 rq->bio->bi_integrity->bip_iter);
 }
 #else /* CONFIG_BLK_DEV_INTEGRITY */
 static inline int blk_rq_count_integrity_sg(struct request_queue *q,
@@ -177,9 +178,9 @@  static inline int blk_integrity_rq(struct request *rq)
 	return 0;
 }
 
-static inline struct bio_vec *rq_integrity_vec(struct request *rq)
+static inline struct bio_vec rq_integrity_vec(struct request *rq)
 {
-	return NULL;
+	return (struct bio_vec){0};
 }
 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 #endif /* _LINUX_BLK_INTEGRITY_H */