On 06/26/18 18:13, Ming Lei wrote:
On Tue, Jun 26, 2018 at 03:26:24PM -0700, Bart Van Assche wrote:
There is no good reason to use different code paths for different
request operations. Hence remove the switch/case statement from
bio_clone_bioset().
Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Ming Lei <ming.lei@xxxxxxxxxx>
---
block/bio.c | 15 ++-------------
1 file changed, 2 insertions(+), 13 deletions(-)
diff --git a/block/bio.c b/block/bio.c
index f7e3d88bd0b6..4c27cc9ea55e 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -691,19 +691,8 @@ struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector;
bio->bi_iter.bi_size = bio_src->bi_iter.bi_size;
- switch (bio_op(bio)) {
- case REQ_OP_DISCARD:
- case REQ_OP_SECURE_ERASE:
- case REQ_OP_WRITE_ZEROES:
- break;
- case REQ_OP_WRITE_SAME:
- bio->bi_io_vec[bio->bi_vcnt++] = bio_src->bi_io_vec[0];
- break;
- default:
- bio_for_each_segment(bv, bio_src, iter)
- bio->bi_io_vec[bio->bi_vcnt++] = bv;
- break;
- }
+ bio_for_each_segment(bv, bio_src, iter)
+ bio->bi_io_vec[bio->bi_vcnt++] = bv;
The above change may not be correct for WRITE_SAME, since
bio_src->bi_iter.bi_size should be the actual bytes to write by drive.
Since bio_for_each_segment() neither modifies bio_src->bi_iter nor
bio->bi_iter, the above patch retains the value copied into
bio->bi_iter.bi_size before bio_for_each_segment() was called. In other
words, bio_src->bi_iter.bi_size is not modified and the resulting
bio->bi_iter.bi_size should be identical with or without this patch.
Also Christoph has killed bio_clone_bioset() already, and I think that is
correct thing to do, see:
https://marc.info/?l=linux-block&m=152938432207215&w=2
Anyway, I'm fine with using Christoph's approach and dropping this patch.
Bart.
