[PATCHv2 2/2] blk-mq-dma: bring back p2p request flags

[Keith Busch <kbusch@meta.com>]

From: Keith Busch <kbusch@kernel.org>

We need to consider data and metadata dma mapping types separately. The
request and bio integrity payload have enough flag bits to internally
track the mapping type for each. Use these so the caller doesn't need to
track them, and provide separete request and integrity helpers to the
common code. This will make it easier to scale new mappings, like the
proposed MMIO attribute, without burdening the caller to track such
things.

Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 block/blk-mq-dma.c            |  4 ++++
 drivers/nvme/host/pci.c       | 21 ++++-----------------
 include/linux/bio-integrity.h |  1 +
 include/linux/blk-integrity.h | 14 ++++++++++++++
 include/linux/blk-mq-dma.h    | 11 +++++++++--
 include/linux/blk_types.h     |  2 ++
 6 files changed, 34 insertions(+), 19 deletions(-)

diff --git a/block/blk-mq-dma.c b/block/blk-mq-dma.c
index 660b5e200ccf6..449950029872a 100644
--- a/block/blk-mq-dma.c
+++ b/block/blk-mq-dma.c
@@ -174,6 +174,10 @@ static bool blk_dma_map_iter_start(struct request *req, struct device *dma_dev,
 	switch (pci_p2pdma_state(&iter->p2pdma, dma_dev,
 				 phys_to_page(vec.paddr))) {
 	case PCI_P2PDMA_MAP_BUS_ADDR:
+		if (iter->iter.is_integrity)
+			bio_integrity(req->bio)->bip_flags |= BIP_P2P_DMA;
+		else
+			req->cmd_flags |= REQ_P2PDMA;
 		return blk_dma_map_bus(iter, &vec);
 	case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
 		/*
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index d8a9dee55de33..28e203b894eb1 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -260,12 +260,6 @@ enum nvme_iod_flags {
 	/* single segment dma mapping */
 	IOD_SINGLE_SEGMENT	= 1U << 2,
 
-	/* DMA mapped with PCI_P2PDMA_MAP_BUS_ADDR */
-	IOD_P2P_BUS_ADDR	= 1U << 3,
-
-	/* Metadata DMA mapped with PCI_P2PDMA_MAP_BUS_ADDR */
-	IOD_META_P2P_BUS_ADDR	= 1U << 4,
-
 	/* Metadata using non-coalesced MPTR */
 	IOD_SINGLE_META_SEGMENT	= 1U << 5,
 };
@@ -737,9 +731,8 @@ static void nvme_unmap_metadata(struct request *req)
 		return;
 	}
 
-	if (!blk_rq_dma_unmap(req, dma_dev, &iod->meta_dma_state,
-				iod->meta_total_len,
-				iod->flags & IOD_META_P2P_BUS_ADDR)) {
+	if (!blk_rq_integrity_dma_unmap(req, dma_dev, &iod->meta_dma_state,
+					iod->meta_total_len)) {
 		if (nvme_pci_cmd_use_meta_sgl(&iod->cmd))
 			nvme_free_sgls(req, sge, &sge[1]);
 		else
@@ -766,8 +759,7 @@ static void nvme_unmap_data(struct request *req)
 		return;
 	}
 
-	if (!blk_rq_dma_unmap(req, dma_dev, &iod->dma_state, iod->total_len,
-				iod->flags & IOD_P2P_BUS_ADDR)) {
+	if (!blk_rq_dma_unmap(req, dma_dev, &iod->dma_state, iod->total_len)) {
 		if (nvme_pci_cmd_use_sgl(&iod->cmd))
 			nvme_free_sgls(req, iod->descriptors[0],
 				       &iod->cmd.common.dptr.sgl);
@@ -1043,9 +1035,6 @@ static blk_status_t nvme_map_data(struct request *req)
 	if (!blk_rq_dma_map_iter_start(req, dev->dev, &iod->dma_state, &iter))
 		return iter.status;
 
-	if (iter.p2pdma.map == PCI_P2PDMA_MAP_BUS_ADDR)
-		iod->flags |= IOD_P2P_BUS_ADDR;
-
 	if (use_sgl == SGL_FORCED ||
 	    (use_sgl == SGL_SUPPORTED &&
 	     (sgl_threshold && nvme_pci_avg_seg_size(req) >= sgl_threshold)))
@@ -1068,9 +1057,7 @@ static blk_status_t nvme_pci_setup_meta_sgls(struct request *req)
 						&iod->meta_dma_state, &iter))
 		return iter.status;
 
-	if (iter.p2pdma.map == PCI_P2PDMA_MAP_BUS_ADDR)
-		iod->flags |= IOD_META_P2P_BUS_ADDR;
-	else if (blk_rq_dma_map_coalesce(&iod->meta_dma_state))
+	if (blk_rq_dma_map_coalesce(&iod->meta_dma_state))
 		entries = 1;
 
 	/*
diff --git a/include/linux/bio-integrity.h b/include/linux/bio-integrity.h
index 0a25716820fe0..851254f36eb36 100644
--- a/include/linux/bio-integrity.h
+++ b/include/linux/bio-integrity.h
@@ -13,6 +13,7 @@ enum bip_flags {
 	BIP_CHECK_GUARD		= 1 << 5, /* guard check */
 	BIP_CHECK_REFTAG	= 1 << 6, /* reftag check */
 	BIP_CHECK_APPTAG	= 1 << 7, /* apptag check */
+	BIP_P2P_DMA		= 1 << 8, /* using P2P address */
 };
 
 struct bio_integrity_payload {
diff --git a/include/linux/blk-integrity.h b/include/linux/blk-integrity.h
index 78fe2459e6612..4746f3e6ad36d 100644
--- a/include/linux/blk-integrity.h
+++ b/include/linux/blk-integrity.h
@@ -27,6 +27,15 @@ static inline bool queue_limits_stack_integrity_bdev(struct queue_limits *t,
 
 #ifdef CONFIG_BLK_DEV_INTEGRITY
 int blk_rq_map_integrity_sg(struct request *, struct scatterlist *);
+
+static inline bool blk_rq_integrity_dma_unmap(struct request *req,
+		struct device *dma_dev, struct dma_iova_state *state,
+		size_t mapped_len)
+{
+	return blk_dma_unmap(req, dma_dev, state, mapped_len,
+			bio_integrity(req->bio)->bip_flags & BIP_P2P_DMA);
+}
+
 int blk_rq_count_integrity_sg(struct request_queue *, struct bio *);
 int blk_rq_integrity_map_user(struct request *rq, void __user *ubuf,
 			      ssize_t bytes);
@@ -115,6 +124,11 @@ static inline int blk_rq_map_integrity_sg(struct request *q,
 {
 	return 0;
 }
+static inline bool blk_rq_dma_unmap(struct request *req, struct device *dma_dev,
+		struct dma_iova_state *state, size_t mapped_len)
+{
+	return false;
+}
 static inline int blk_rq_integrity_map_user(struct request *rq,
 					    void __user *ubuf,
 					    ssize_t bytes)
diff --git a/include/linux/blk-mq-dma.h b/include/linux/blk-mq-dma.h
index 0f45ea110ca12..51829958d8729 100644
--- a/include/linux/blk-mq-dma.h
+++ b/include/linux/blk-mq-dma.h
@@ -43,7 +43,7 @@ static inline bool blk_rq_dma_map_coalesce(struct dma_iova_state *state)
 }
 
 /**
- * blk_rq_dma_unmap - try to DMA unmap a request
+ * blk_dma_unmap - try to DMA unmap a request
  * @req:	request to unmap
  * @dma_dev:	device to unmap from
  * @state:	DMA IOVA state
@@ -53,7 +53,7 @@ static inline bool blk_rq_dma_map_coalesce(struct dma_iova_state *state)
  * Returns %false if the callers need to manually unmap every DMA segment
  * mapped using @iter or %true if no work is left to be done.
  */
-static inline bool blk_rq_dma_unmap(struct request *req, struct device *dma_dev,
+static inline bool blk_dma_unmap(struct request *req, struct device *dma_dev,
 		struct dma_iova_state *state, size_t mapped_len, bool is_p2p)
 {
 	if (is_p2p)
@@ -68,4 +68,11 @@ static inline bool blk_rq_dma_unmap(struct request *req, struct device *dma_dev,
 	return !dma_need_unmap(dma_dev);
 }
 
+static inline bool blk_rq_dma_unmap(struct request *req, struct device *dma_dev,
+		struct dma_iova_state *state, size_t mapped_len)
+{
+	return blk_dma_unmap(req, dma_dev, state, mapped_len,
+				req->cmd_flags & REQ_P2PDMA);
+}
+
 #endif /* BLK_MQ_DMA_H */
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 930daff207df2..09b99d52fd365 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -386,6 +386,7 @@ enum req_flag_bits {
 	__REQ_DRV,		/* for driver use */
 	__REQ_FS_PRIVATE,	/* for file system (submitter) use */
 	__REQ_ATOMIC,		/* for atomic write operations */
+	__REQ_P2PDMA,		/* contains P2P DMA pages */
 	/*
 	 * Command specific flags, keep last:
 	 */
@@ -418,6 +419,7 @@ enum req_flag_bits {
 #define REQ_DRV		(__force blk_opf_t)(1ULL << __REQ_DRV)
 #define REQ_FS_PRIVATE	(__force blk_opf_t)(1ULL << __REQ_FS_PRIVATE)
 #define REQ_ATOMIC	(__force blk_opf_t)(1ULL << __REQ_ATOMIC)
+#define REQ_P2PDMA	(__force blk_opf_t)(1ULL << __REQ_P2PDMA)
 
 #define REQ_NOUNMAP	(__force blk_opf_t)(1ULL << __REQ_NOUNMAP)
 
-- 
2.47.3