This patch adds support for larger requests in blk_rq_map_user_iov by
allowing it to build multiple bios for a request. This functionality
used to exist for the non-vectored blk_rq_map_user in the past, and
this patch reuses the existing functionality for it on the unmap side,
which stuck around. Thanks to the iov_iter API supporting multiple
bios is fairly trivial, as we can just iterate the iov until we've
consumed the whole iov_iter.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reported-by: Jeff Lien <Jeff.Lien@xxxxxxxx>
Tested-by: Jeff Lien <Jeff.Lien@xxxxxxxx>
---
block/blk-map.c | 91 ++++++++++++++++++++++++++++++++++++++-------------------
1 file changed, 61 insertions(+), 30 deletions(-)
diff --git a/block/blk-map.c b/block/blk-map.c
index f565e11..a54f054 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -57,6 +57,49 @@ static int __blk_rq_unmap_user(struct bio *bio)
return ret;
}
+static int __blk_rq_map_user_iov(struct request *rq,
+ struct rq_map_data *map_data, struct iov_iter *iter,
+ gfp_t gfp_mask, bool copy)
+{
+ struct request_queue *q = rq->q;
+ struct bio *bio, *orig_bio;
+ int ret;
+
+ if (copy)
+ bio = bio_copy_user_iov(q, map_data, iter, gfp_mask);
+ else
+ bio = bio_map_user_iov(q, iter, gfp_mask);
+
+ if (IS_ERR(bio))
+ return PTR_ERR(bio);
+
+ if (map_data && map_data->null_mapped)
+ bio_set_flag(bio, BIO_NULL_MAPPED);
+
+ iov_iter_advance(iter, bio->bi_iter.bi_size);
+ if (map_data)
+ map_data->offset += bio->bi_iter.bi_size;
+
+ orig_bio = bio;
+ blk_queue_bounce(q, &bio);
+
+ /*
+ * We link the bounce buffer in and could have to traverse it
+ * later so we have to get a ref to prevent it from being freed
+ */
+ bio_get(bio);
+
+ ret = blk_rq_append_bio(q, rq, bio);
+ if (ret) {
+ bio_endio(bio);
+ __blk_rq_unmap_user(orig_bio);
+ bio_put(bio);
+ return ret;
+ }
+
+ return 0;
+}
+
/**
* blk_rq_map_user_iov - map user data to a request, for REQ_TYPE_BLOCK_PC usage
* @q: request queue where request should be inserted
@@ -82,10 +125,11 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
struct rq_map_data *map_data,
const struct iov_iter *iter, gfp_t gfp_mask)
{
- struct bio *bio;
- int unaligned = 0;
- struct iov_iter i;
struct iovec iov, prv = {.iov_base = NULL, .iov_len = 0};
+ bool copy = (q->dma_pad_mask & iter->count) || map_data;
+ struct bio *bio = NULL;
+ struct iov_iter i;
+ int ret;
if (!iter || !iter->count)
return -EINVAL;
@@ -101,42 +145,29 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
*/
if ((uaddr & queue_dma_alignment(q)) ||
iovec_gap_to_prv(q, &prv, &iov))
- unaligned = 1;
+ copy = true;
prv.iov_base = iov.iov_base;
prv.iov_len = iov.iov_len;
}
- if (unaligned || (q->dma_pad_mask & iter->count) || map_data)
- bio = bio_copy_user_iov(q, map_data, iter, gfp_mask);
- else
- bio = bio_map_user_iov(q, iter, gfp_mask);
-
- if (IS_ERR(bio))
- return PTR_ERR(bio);
-
- if (map_data && map_data->null_mapped)
- bio_set_flag(bio, BIO_NULL_MAPPED);
-
- if (bio->bi_iter.bi_size != iter->count) {
- /*
- * Grab an extra reference to this bio, as bio_unmap_user()
- * expects to be able to drop it twice as it happens on the
- * normal IO completion path
- */
- bio_get(bio);
- bio_endio(bio);
- __blk_rq_unmap_user(bio);
- return -EINVAL;
- }
+ i = *iter;
+ do {
+ ret =__blk_rq_map_user_iov(rq, map_data, &i, gfp_mask, copy);
+ if (ret)
+ goto unmap_rq;
+ if (!bio)
+ bio = rq->bio;
+ } while (iov_iter_count(&i));
if (!bio_flagged(bio, BIO_USER_MAPPED))
rq->cmd_flags |= REQ_COPY_USER;
-
- blk_queue_bounce(q, &bio);
- bio_get(bio);
- blk_rq_bio_prep(q, rq, bio);
return 0;
+
+unmap_rq:
+ __blk_rq_unmap_user(bio);
+ rq->bio = NULL;
+ return -EINVAL;
}
EXPORT_SYMBOL(blk_rq_map_user_iov);
--
2.1.4
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