On Wed, Sep 07, 2022 at 03:32:26PM +0000, Chaitanya Kulkarni wrote:
On 9/5/22 23:27, Kanchan Joshi wrote:
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 <joshi.k@xxxxxxxxxxx>
Signed-off-by: Anuj Gupta <anuj20.g@xxxxxxxxxxx>
---
block/blk-map.c | 94 +++++++++++++++++++++++++++++++++++++-----
include/linux/blk-mq.h | 1 +
2 files changed, 85 insertions(+), 10 deletions(-)
diff --git a/block/blk-map.c b/block/blk-map.c
index f3768876d618..e2f268167342 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];
@@ -612,6 +623,69 @@ 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 iter_count, nr_segs;
+ struct bio *bio;
+ struct bio_vec *bv, *bvec_arr, *bvprvp = NULL;
+ struct queue_limits *lim = &q->limits;
+ unsigned int nsegs = 0, bytes = 0;
+ int ret, i;
+
consider this (untested), it also sets the variable i data type same
as it comparison variable in nr_segs the loop i.e. size_t :-
+ struct bio_vec *bv, *bvec_arr, *bvprvp = NULL;
+ struct request_queue *q = rq->q;
+ struct queue_limits *lim = &q->limits;
+ unsigned int nsegs = 0, bytes = 0;
+ size_t iter_count, nr_segs, i;
+ struct bio *bio;
+ int ret;
+ iter_count = iov_iter_count(iter);
+ nr_segs = iter->nr_segs;
+
+ if (!iter_count || (iter_count >> 9) > queue_max_hw_sectors(q))
+ return -EINVAL;
can we remove braces for iter_count >> 9 without impacting the intended
functionality?
I think removing that make it hard to read.
I will fold all other changes you mentioned in v6.
