diff options
| author | Christoph Hellwig <hch@lst.de> | 2019-04-11 08:23:27 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2019-04-12 17:06:36 +0200 |
| commit | 8a96a0e408102fb7aa73d8aa0b5e2219cfd51e55 (patch) | |
| tree | a62d8c0f583ee464e40b5a41fae7cd4b891b7f31 | |
| parent | Merge branch 'md-next' of https://github.com/liu-song-6/linux into for-5.2/block (diff) | |
| download | linux-8a96a0e408102fb7aa73d8aa0b5e2219cfd51e55.tar.xz linux-8a96a0e408102fb7aa73d8aa0b5e2219cfd51e55.zip | |
block: rewrite blk_bvec_map_sg to avoid a nth_page call
The offset in scatterlists is allowed to be larger than the page size,
so don't go to great length to avoid that case and simplify the
arithmetics.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | block/blk-merge.c | 21 |
1 files changed, 6 insertions, 15 deletions
diff --git a/block/blk-merge.c b/block/blk-merge.c index 895795cdb145..247b17f2a0f6 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -469,26 +469,17 @@ static unsigned blk_bvec_map_sg(struct request_queue *q, struct scatterlist **sg) { unsigned nbytes = bvec->bv_len; - unsigned nsegs = 0, total = 0, offset = 0; + unsigned nsegs = 0, total = 0; while (nbytes > 0) { - unsigned seg_size; - struct page *pg; - unsigned idx; + unsigned offset = bvec->bv_offset + total; + unsigned len = min(get_max_segment_size(q, offset), nbytes); *sg = blk_next_sg(sg, sglist); + sg_set_page(*sg, bvec->bv_page, len, offset); - seg_size = get_max_segment_size(q, bvec->bv_offset + total); - seg_size = min(nbytes, seg_size); - - offset = (total + bvec->bv_offset) % PAGE_SIZE; - idx = (total + bvec->bv_offset) / PAGE_SIZE; - pg = bvec_nth_page(bvec->bv_page, idx); - - sg_set_page(*sg, pg, seg_size, offset); - - total += seg_size; - nbytes -= seg_size; + total += len; + nbytes -= len; nsegs++; } |