linux-kernel - [RFC PATCH 21/28] nvmet: Split nvmet_bdev_execute

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Message-Id: <20190620161240.22738-22-logang@deltatee.com>
Date:   Thu, 20 Jun 2019 10:12:33 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        linux-nvme@...ts.infradead.org, linux-pci@...r.kernel.org,
        linux-rdma@...r.kernel.org
Cc:     Jens Axboe <axboe@...nel.dk>, Christoph Hellwig <hch@....de>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Sagi Grimberg <sagi@...mberg.me>,
        Keith Busch <kbusch@...nel.org>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Stephen Bates <sbates@...thlin.com>,
        Logan Gunthorpe <logang@...tatee.com>
Subject: [RFC PATCH 21/28] nvmet: Split nvmet_bdev_execute_rw() into a helper function

Move the mapping of the SG and submission of the bio
into a static helper function to reduce the complexity.

This will be useful in the next patch which submits dma-direct bios
for P2P requests.

Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
---
 drivers/nvme/target/io-cmd-bdev.c | 52 ++++++++++++++++++-------------
 1 file changed, 31 insertions(+), 21 deletions(-)

diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
index 7a1cf6437a6a..061d40b020c7 100644
--- a/drivers/nvme/target/io-cmd-bdev.c
+++ b/drivers/nvme/target/io-cmd-bdev.c
@@ -103,13 +103,41 @@ static void nvmet_bio_done(struct bio *bio)
 		bio_put(bio);
 }
 
+static void nvmet_submit_sg(struct nvmet_req *req, struct bio *bio,
+			    sector_t sector)
+{
+	int sg_cnt = req->sg_cnt;
+	struct scatterlist *sg;
+	int i;
+
+	for_each_sg(req->sg, sg, req->sg_cnt, i) {
+		while (bio_add_page(bio, sg_page(sg), sg->length, sg->offset)
+				!= sg->length) {
+			struct bio *prev = bio;
+
+			bio = bio_alloc(GFP_KERNEL,
+					min(sg_cnt, BIO_MAX_PAGES));
+			bio_set_dev(bio, req->ns->bdev);
+			bio->bi_iter.bi_sector = sector;
+			bio->bi_opf = prev->bi_opf;
+
+			bio_chain(bio, prev);
+			submit_bio(prev);
+		}
+
+		sector += sg->length >> 9;
+		sg_cnt--;
+	}
+
+	submit_bio(bio);
+}
+
 static void nvmet_bdev_execute_rw(struct nvmet_req *req)
 {
 	int sg_cnt = req->sg_cnt;
 	struct bio *bio;
-	struct scatterlist *sg;
 	sector_t sector;
-	int op, op_flags = 0, i;
+	int op, op_flags = 0;
 
 	if (!req->sg_cnt) {
 		nvmet_req_complete(req, 0);
@@ -143,25 +171,7 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
 	bio->bi_end_io = nvmet_bio_done;
 	bio_set_op_attrs(bio, op, op_flags);
 
-	for_each_sg(req->sg, sg, req->sg_cnt, i) {
-		while (bio_add_page(bio, sg_page(sg), sg->length, sg->offset)
-				!= sg->length) {
-			struct bio *prev = bio;
-
-			bio = bio_alloc(GFP_KERNEL, min(sg_cnt, BIO_MAX_PAGES));
-			bio_set_dev(bio, req->ns->bdev);
-			bio->bi_iter.bi_sector = sector;
-			bio_set_op_attrs(bio, op, op_flags);
-
-			bio_chain(bio, prev);
-			submit_bio(prev);
-		}
-
-		sector += sg->length >> 9;
-		sg_cnt--;
-	}
-
-	submit_bio(bio);
+	nvmet_submit_sg(req, bio, sector);
 }
 
 static void nvmet_bdev_execute_flush(struct nvmet_req *req)
-- 
2.20.1