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| author | FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> | 2008-09-02 16:20:19 +0900 |
|---|---|---|
| committer | Jens Axboe <jens.axboe@oracle.com> | 2008-10-09 08:56:11 +0200 |
| commit | 818827669d85b84241696ffef2de485db46b0b5e (patch) | |
| tree | 694d09728733e65d604bf3e1f13679db73fc1d9a /block | |
| parent | 839e96afba87117befd39cf4e43f156edc8047a7 (diff) | |
| download | lwn-818827669d85b84241696ffef2de485db46b0b5e.tar.gz lwn-818827669d85b84241696ffef2de485db46b0b5e.zip | |
block: make blk_rq_map_user take a NULL user-space buffer
This patch changes blk_rq_map_user to accept a NULL user-space buffer
with a READ command if rq_map_data is not NULL. Thus a caller can pass
page frames to lk_rq_map_user to just set up a request and bios with
page frames propely. bio_uncopy_user (called via blk_rq_unmap_user)
doesn't copy data to user space with such request.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-map.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/block/blk-map.c b/block/blk-map.c index 572140cda5ff..4849fa36161e 100644 --- a/block/blk-map.c +++ b/block/blk-map.c @@ -42,7 +42,7 @@ static int __blk_rq_unmap_user(struct bio *bio) static int __blk_rq_map_user(struct request_queue *q, struct request *rq, struct rq_map_data *map_data, void __user *ubuf, - unsigned int len, gfp_t gfp_mask) + unsigned int len, int null_mapped, gfp_t gfp_mask) { unsigned long uaddr; struct bio *bio, *orig_bio; @@ -63,6 +63,9 @@ static int __blk_rq_map_user(struct request_queue *q, struct request *rq, if (IS_ERR(bio)) return PTR_ERR(bio); + if (null_mapped) + bio->bi_flags |= (1 << BIO_NULL_MAPPED); + orig_bio = bio; blk_queue_bounce(q, &bio); @@ -111,12 +114,17 @@ int blk_rq_map_user(struct request_queue *q, struct request *rq, { unsigned long bytes_read = 0; struct bio *bio = NULL; - int ret; + int ret, null_mapped = 0; if (len > (q->max_hw_sectors << 9)) return -EINVAL; - if (!len || !ubuf) + if (!len) return -EINVAL; + if (!ubuf) { + if (!map_data || rq_data_dir(rq) != READ) + return -EINVAL; + null_mapped = 1; + } while (bytes_read != len) { unsigned long map_len, end, start; @@ -135,7 +143,7 @@ int blk_rq_map_user(struct request_queue *q, struct request *rq, map_len -= PAGE_SIZE; ret = __blk_rq_map_user(q, rq, map_data, ubuf, map_len, - gfp_mask); + null_mapped, gfp_mask); if (ret < 0) goto unmap_rq; if (!bio) |