block: add support for write hints in a bio
No functional changes in this patch, we just use up some holes
in the bio and request structures to define a write hint that
we psas down the stack.
Ensure that we don't merge requests that have different life time
hints assigned to them, and that we inherit the write hint when
cloning a bio.
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/bio.c b/block/bio.c
index 89a51bd..9cf98b2 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -596,6 +596,7 @@ void __bio_clone_fast(struct bio *bio, struct bio *bio_src)
bio->bi_bdev = bio_src->bi_bdev;
bio_set_flag(bio, BIO_CLONED);
bio->bi_opf = bio_src->bi_opf;
+ bio->bi_write_hint = bio_src->bi_write_hint;
bio->bi_iter = bio_src->bi_iter;
bio->bi_io_vec = bio_src->bi_io_vec;
@@ -679,6 +680,7 @@ struct bio *bio_clone_bioset(struct bio *bio_src, gfp_t gfp_mask,
return NULL;
bio->bi_bdev = bio_src->bi_bdev;
bio->bi_opf = bio_src->bi_opf;
+ bio->bi_write_hint = bio_src->bi_write_hint;
bio->bi_iter.bi_sector = bio_src->bi_iter.bi_sector;
bio->bi_iter.bi_size = bio_src->bi_iter.bi_size;