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From: Kanchan Joshi <[email protected]>
To: [email protected], [email protected], [email protected]
Cc: [email protected], [email protected],
	[email protected], [email protected],
	Kanchan Joshi <[email protected]>,
	Anuj Gupta <[email protected]>
Subject: [PATCH for-next v8 4/5] block: add helper to map bvec iterator for passthrough
Date: Fri, 23 Sep 2022 14:58:53 +0530	[thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>

Add blk_rq_map_user_bvec which maps the bvec iterator into a bio and
places that into the request. This helper will be used in nvme for
uring-passthrough with fixed-buffer.
While at it, create another helper bio_map_get to reduce the code
duplication.

Signed-off-by: Kanchan Joshi <[email protected]>
Signed-off-by: Anuj Gupta <[email protected]>
---
 block/blk-map.c        | 111 +++++++++++++++++++++++++++++++++++++----
 include/linux/blk-mq.h |   1 +
 2 files changed, 102 insertions(+), 10 deletions(-)

diff --git a/block/blk-map.c b/block/blk-map.c
index 7693f8e3c454..d6265d49b15b 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -241,17 +241,10 @@ static void bio_map_put(struct bio *bio)
 	}
 }
 
-static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
+static struct bio *bio_map_get(struct request *rq, unsigned int nr_vecs,
 		gfp_t gfp_mask)
 {
-	unsigned int max_sectors = queue_max_hw_sectors(rq->q);
-	unsigned int nr_vecs = iov_iter_npages(iter, BIO_MAX_VECS);
 	struct bio *bio;
-	int ret;
-	int j;
-
-	if (!iov_iter_count(iter))
-		return -EINVAL;
 
 	if (rq->cmd_flags & REQ_POLLED) {
 		blk_opf_t opf = rq->cmd_flags | REQ_ALLOC_CACHE;
@@ -259,13 +252,31 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
 		bio = bio_alloc_bioset(NULL, nr_vecs, opf, gfp_mask,
 					&fs_bio_set);
 		if (!bio)
-			return -ENOMEM;
+			return NULL;
 	} else {
 		bio = bio_kmalloc(nr_vecs, gfp_mask);
 		if (!bio)
-			return -ENOMEM;
+			return NULL;
 		bio_init(bio, NULL, bio->bi_inline_vecs, nr_vecs, req_op(rq));
 	}
+	return bio;
+}
+
+static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
+		gfp_t gfp_mask)
+{
+	unsigned int max_sectors = queue_max_hw_sectors(rq->q);
+	unsigned int nr_vecs = iov_iter_npages(iter, BIO_MAX_VECS);
+	struct bio *bio;
+	int ret;
+	int j;
+
+	if (!iov_iter_count(iter))
+		return -EINVAL;
+
+	bio = bio_map_get(rq, nr_vecs, gfp_mask);
+	if (bio == NULL)
+		return -ENOMEM;
 
 	while (iov_iter_count(iter)) {
 		struct page **pages, *stack_pages[UIO_FASTIOV];
@@ -611,6 +622,86 @@ int blk_rq_map_user(struct request_queue *q, struct request *rq,
 }
 EXPORT_SYMBOL(blk_rq_map_user);
 
+/* Prepare bio for passthrough IO given an existing bvec iter */
+int blk_rq_map_user_bvec(struct request *rq, struct iov_iter *iter)
+{
+	struct request_queue *q = rq->q;
+	size_t nr_iter, nr_segs, i;
+	struct bio *bio = NULL;
+	struct bio_vec *bv, *bvecs, *bvprvp = NULL;
+	struct queue_limits *lim = &q->limits;
+	unsigned int nsegs = 0, bytes = 0;
+	bool copy = false;
+	int ret;
+	unsigned long align = q->dma_pad_mask | queue_dma_alignment(q);
+
+	/* see if we need to copy pages due to any weird situation */
+	if (blk_queue_may_bounce(q))
+		copy = true;
+	else if (iov_iter_alignment(iter) & align)
+		copy = true;
+
+	if (copy) {
+		do {
+			ret = bio_copy_user_iov(rq, NULL, iter, GFP_KERNEL);
+			if (ret) {
+				blk_rq_unmap_user(bio);
+				rq->bio = NULL;
+				break;
+			}
+			if (!bio)
+				bio = rq->bio;
+		} while (iov_iter_count(iter));
+
+		return ret;
+	}
+	/* common (non-copy) case handling */
+	nr_iter = iov_iter_count(iter);
+	nr_segs = iter->nr_segs;
+
+	if (!nr_iter || (nr_iter >> SECTOR_SHIFT) > queue_max_hw_sectors(q))
+		return -EINVAL;
+	if (nr_segs > queue_max_segments(q))
+		return -EINVAL;
+
+	/* no iovecs to alloc, as we already have a BVEC iterator */
+	bio = bio_map_get(rq, 0, GFP_KERNEL);
+	if (bio == NULL)
+		return -ENOMEM;
+
+	bio_iov_bvec_set(bio, iter);
+	blk_rq_bio_prep(rq, bio, nr_segs);
+
+	/* loop to perform a bunch of sanity checks */
+	bvecs = (struct bio_vec *)iter->bvec;
+	for (i = 0; i < nr_segs; i++) {
+		bv = &bvecs[i];
+		/*
+		 * If the queue doesn't support SG gaps and adding this
+		 * offset would create a gap, disallow it.
+		 */
+		if (bvprvp && bvec_gap_to_prev(lim, bvprvp, bv->bv_offset))
+			goto put_bio;
+
+		/* check full condition */
+		if (nsegs >= nr_segs || bytes > UINT_MAX - bv->bv_len)
+			goto put_bio;
+		if (bytes + bv->bv_len > nr_iter)
+			goto put_bio;
+		if (bv->bv_offset + bv->bv_len > PAGE_SIZE)
+			goto put_bio;
+
+		nsegs++;
+		bytes += bv->bv_len;
+		bvprvp = bv;
+	}
+	return 0;
+put_bio:
+	bio_map_put(bio);
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(blk_rq_map_user_bvec);
+
 /**
  * blk_rq_unmap_user - unmap a request with user data
  * @bio:	       start of bio list
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 00a15808c137..1a9ae17e49be 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -977,6 +977,7 @@ struct rq_map_data {
 	bool from_user;
 };
 
+int blk_rq_map_user_bvec(struct request *rq, struct iov_iter *iter);
 int blk_rq_map_user(struct request_queue *, struct request *,
 		struct rq_map_data *, void __user *, unsigned long, gfp_t);
 int blk_rq_map_user_iov(struct request_queue *, struct request *,
-- 
2.25.1


  parent reply	other threads:[~2022-09-23  9:42 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20220923093906epcas5p1308a262f3de722a923339c2e804fc5ee@epcas5p1.samsung.com>
2022-09-23  9:28 ` [PATCH for-next v8 0/5] fixed-buffer for uring-cmd/passthru Kanchan Joshi
     [not found]   ` <CGME20220923093910epcas5p2624d93c6cb5caebb5f9203a1b8f4f5b1@epcas5p2.samsung.com>
2022-09-23  9:28     ` [PATCH for-next v8 1/5] io_uring: add io_uring_cmd_import_fixed Kanchan Joshi
     [not found]   ` <CGME20220923093913epcas5p4d91766a750d6f5e87a1da0b92f6c4a2e@epcas5p4.samsung.com>
2022-09-23  9:28     ` [PATCH for-next v8 2/5] io_uring: introduce fixed buffer support for io_uring_cmd Kanchan Joshi
     [not found]   ` <CGME20220923093916epcas5p387fdd905413f6d90babecf5d14da5b67@epcas5p3.samsung.com>
2022-09-23  9:28     ` [PATCH for-next v8 3/5] nvme: refactor nvme_alloc_user_request Kanchan Joshi
2022-09-23 15:38       ` Christoph Hellwig
2022-09-25 17:39         ` Kanchan Joshi
2022-09-25 19:43         ` Kanchan Joshi
2022-09-26 14:51           ` Christoph Hellwig
2022-09-27 16:57             ` Kanchan Joshi
     [not found]   ` <CGME20220923093919epcas5p3d019fa1db990101478b8d6673ac0eaa6@epcas5p3.samsung.com>
2022-09-23  9:28     ` Kanchan Joshi [this message]
2022-09-23 15:30       ` [PATCH for-next v8 4/5] block: add helper to map bvec iterator for passthrough Christoph Hellwig
     [not found]   ` <CGME20220923093924epcas5p1e1723a3937cb3331c77e55bd1a785e57@epcas5p1.samsung.com>
2022-09-23  9:28     ` [PATCH for-next v8 5/5] nvme: wire up fixed buffer support for nvme passthrough Kanchan Joshi
2022-09-23 15:40       ` Christoph Hellwig
2022-09-23 14:15   ` [PATCH for-next v8 0/5] fixed-buffer for uring-cmd/passthru Jens Axboe
2022-09-25 17:56     ` Kanchan Joshi

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