diff options
| -rw-r--r-- | block/blk-map.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/block/blk-map.c b/block/blk-map.c index bc5ce60691c..a7cf63ccb5c 100644 --- a/block/blk-map.c +++ b/block/blk-map.c @@ -139,6 +139,23 @@ int blk_rq_map_user(struct request_queue *q, struct request *rq, ubuf += ret; } + /* + * __blk_rq_map_user() copies the buffers if starting address + * or length isn't aligned. As the copied buffer is always + * page aligned, we know that there's enough room for padding. + * Extend the last bio and update rq->data_len accordingly. + * + * On unmap, bio_uncopy_user() will use unmodified + * bio_map_data pointed to by bio->bi_private. + */ + if (len & queue_dma_alignment(q)) { + unsigned int pad_len = (queue_dma_alignment(q) & ~len) + 1; + struct bio *bio = rq->biotail; + + bio->bi_io_vec[bio->bi_vcnt - 1].bv_len += pad_len; + bio->bi_size += pad_len; + } + rq->buffer = rq->data = NULL; return 0; unmap_rq: |