diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-map.c | 21 |
1 files changed, 20 insertions, 1 deletions
diff --git a/block/blk-map.c b/block/blk-map.c index 3c942bd6422..0b1af5a3537 100644 --- a/block/blk-map.c +++ b/block/blk-map.c @@ -255,10 +255,18 @@ EXPORT_SYMBOL(blk_rq_unmap_user); * @kbuf: the kernel buffer * @len: length of user data * @gfp_mask: memory allocation flags + * + * Description: + * Data will be mapped directly if possible. Otherwise a bounce + * buffer is used. */ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf, unsigned int len, gfp_t gfp_mask) { + unsigned long kaddr; + unsigned int alignment; + int reading = rq_data_dir(rq) == READ; + int do_copy = 0; struct bio *bio; if (len > (q->max_hw_sectors << 9)) @@ -266,13 +274,24 @@ int blk_rq_map_kern(struct request_queue *q, struct request *rq, void *kbuf, if (!len || !kbuf) return -EINVAL; - bio = bio_map_kern(q, kbuf, len, gfp_mask); + kaddr = (unsigned long)kbuf; + alignment = queue_dma_alignment(q) | q->dma_pad_mask; + do_copy = ((kaddr & alignment) || (len & alignment)); + + if (do_copy) + bio = bio_copy_kern(q, kbuf, len, gfp_mask, reading); + else + bio = bio_map_kern(q, kbuf, len, gfp_mask); + if (IS_ERR(bio)) return PTR_ERR(bio); if (rq_data_dir(rq) == WRITE) bio->bi_rw |= (1 << BIO_RW); + if (do_copy) + rq->cmd_flags |= REQ_COPY_USER; + blk_rq_bio_prep(q, rq, bio); blk_queue_bounce(q, &rq->bio); rq->buffer = rq->data = NULL; |