blk-mq: remove REQ_P2PDMA flag

It's not serving any particular purpose. pci_p2pdma_state() already has
all the appropriate checks, so the config and flag checks are not
guarding anything.

Signed-off-by: Keith Busch <[email protected]>

Author: keithbusch

block/bio.c

@@ -981,7 +981,7 @@ void __bio_add_page(struct bio *bio, struct page *page,
 	WARN_ON_ONCE(bio_full(bio, len));
 
 	if (is_pci_p2pdma_page(page))
-		bio->bi_opf |= REQ_P2PDMA | REQ_NOMERGE;
+		bio->bi_opf |= REQ_NOMERGE;
 
 	bvec_set_page(&bio->bi_io_vec[bio->bi_vcnt], page, len, off);
 	bio->bi_iter.bi_size += len;

block/blk-mq-dma.c

@@ -173,22 +173,20 @@ bool blk_rq_dma_map_iter_start(struct request *req, struct device *dma_dev,
 	if (!blk_map_iter_next(req, &iter->iter))
 		return false;
 
-	if (IS_ENABLED(CONFIG_PCI_P2PDMA) && (req->cmd_flags & REQ_P2PDMA)) {
-		switch (pci_p2pdma_state(&iter->p2pdma, dma_dev,
-					 phys_to_page(iter->iter.paddr))) {
-		case PCI_P2PDMA_MAP_BUS_ADDR:
-			return blk_dma_map_bus(iter);
-		case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
-			/*
-			 * P2P transfers through the host bridge are treated the
-			 * same as non-P2P transfers below and during unmap.
-			 */
-			req->cmd_flags &= ~REQ_P2PDMA;
-			break;
-		default:
-			iter->status = BLK_STS_INVAL;
-			return false;
-		}
+	switch (pci_p2pdma_state(&iter->p2pdma, dma_dev,
+				 phys_to_page(iter->iter.paddr))) {
+	case PCI_P2PDMA_MAP_BUS_ADDR:
+		return blk_dma_map_bus(iter);
+	case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
+		/*
+		 * P2P transfers through the host bridge are treated the
+		 * same as non-P2P transfers below and during unmap.
+		 */
+	case PCI_P2PDMA_MAP_NONE:
+		break;
+	default:
+		iter->status = BLK_STS_INVAL;
+		return false;
 	}
 
 	if (blk_can_dma_map_iova(req, dma_dev) &&

include/linux/blk_types.h

@@ -419,7 +419,6 @@ 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)