From: Eric Wheeler <[email protected]> Since dm-crypt queues writes (and sometimes reads) to a different kernel thread (workqueue), the bios will dispatch from tasks with different io_context->ioprio settings than the submitting task, thus giving incorrect ioprio hints to the io scheduler.
By assigning the ioprio to the bio before queuing to a workqueue, the original submitting task's io_context->ioprio setting can be retained through the life of the bio. We only set the bio's ioprio in dm-crypt if not already set (by somewhere else, higher in the stack). Signed-off-by: Eric Wheeler <[email protected]> Cc: Mikulas Patocka <[email protected]> Cc: Alasdair Kergon <[email protected]> Cc: Jens Axboe <[email protected]> Cc: [email protected] Signed-off-by: Mike Snitzer <[email protected]> --- block/bio.c | 24 ++++++++++++++++++++++++ drivers/md/dm-crypt.c | 15 +++++++++++++-- include/linux/bio.h | 2 ++ 3 files changed, 39 insertions(+), 2 deletions(-) [Jens, too much block code for me to take, please feel free to pick this up, I tweaked Eric's original for 2 years ago (sorry this slipped through the cracks Eric!): https://patchwork.kernel.org/patch/9474535/ ] diff --git a/block/bio.c b/block/bio.c index 0c2208a5446d..ed68fdd78547 100644 --- a/block/bio.c +++ b/block/bio.c @@ -647,6 +647,30 @@ struct bio *bio_clone_fast(struct bio *bio, gfp_t gfp_mask, struct bio_set *bs) } EXPORT_SYMBOL(bio_clone_fast); +/** + * bio_set_task_prio - set bio's ioprio to task's ioprio, if any. + * @bio: bio to set the ioprio of, can be NULL + * @task: task of interest + * @gfp_flags: allocation flags, used if allocation is necessary + * @node: allocation node, used if allocation is necessary + */ +void bio_set_task_prio(struct bio *bio, struct task_struct *task, + gfp_t gfp_flags, int node) +{ + struct io_context *ioc; + + if (!bio) + return; + + ioc = get_task_io_context(current, gfp_flags, node); + if (ioc) { + if (ioprio_valid(ioc->ioprio)) + bio_set_prio(bio, ioc->ioprio); + put_io_context(ioc); + } +} +EXPORT_SYMBOL(bio_set_task_prio); + /** * bio_add_pc_page - attempt to add page to bio * @q: the target queue diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c index 509fb20f7f86..4e3f0962f230 100644 --- a/drivers/md/dm-crypt.c +++ b/drivers/md/dm-crypt.c @@ -1548,6 +1548,7 @@ static void clone_init(struct dm_crypt_io *io, struct bio *clone) clone->bi_private = io; clone->bi_end_io = crypt_endio; bio_set_dev(clone, cc->dev->bdev); + bio_set_prio(clone, bio_prio(io->base_bio)); clone->bi_opf = io->base_bio->bi_opf; } @@ -2916,10 +2917,20 @@ static int crypt_map(struct dm_target *ti, struct bio *bio) io->ctx.r.req = (struct skcipher_request *)(io + 1); if (bio_data_dir(io->base_bio) == READ) { - if (kcryptd_io_read(io, GFP_NOWAIT)) + if (kcryptd_io_read(io, GFP_NOWAIT)) { + if (!ioprio_valid(bio_prio(io->base_bio))) { + bio_set_task_prio(io->base_bio, current, + GFP_NOIO, NUMA_NO_NODE); + } kcryptd_queue_read(io); - } else + } + } else { + if (!ioprio_valid(bio_prio(io->base_bio))) { + bio_set_task_prio(io->base_bio, current, + GFP_NOIO, NUMA_NO_NODE); + } kcryptd_queue_crypt(io); + } return DM_MAPIO_SUBMITTED; } diff --git a/include/linux/bio.h b/include/linux/bio.h index 056fb627edb3..93e11424e7f0 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -46,6 +46,8 @@ #define bio_prio(bio) (bio)->bi_ioprio #define bio_set_prio(bio, prio) ((bio)->bi_ioprio = prio) +extern void bio_set_task_prio(struct bio *bio, struct task_struct *task, + gfp_t gfp_flags, int node); #define bio_iter_iovec(bio, iter) \ bvec_iter_bvec((bio)->bi_io_vec, (iter)) -- 2.15.0 -- dm-devel mailing list [email protected] https://www.redhat.com/mailman/listinfo/dm-devel
