On Tue, Sep 15, 2020 at 01:23:57PM -0400, Mike Snitzer wrote:
> blk_queue_split() has become compulsory from .submit_bio -- regardless
> of whether it is recursing. Update DM core to always call
> blk_queue_split().
>
> dm_queue_split() is removed because __split_and_process_bio() handles
> splitting as needed.
>
> Signed-off-by: Mike Snitzer <snit...@redhat.com>
> ---
> drivers/md/dm.c | 45 +--------------------------------------------
> 1 file changed, 1 insertion(+), 44 deletions(-)
>
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index fb0255d25e4b..0bae9f26dc8e 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -1530,22 +1530,6 @@ static int __send_write_zeroes(struct clone_info *ci,
> struct dm_target *ti)
> return __send_changing_extent_only(ci, ti,
> get_num_write_zeroes_bios(ti));
> }
>
> -static bool is_abnormal_io(struct bio *bio)
> -{
> - bool r = false;
> -
> - switch (bio_op(bio)) {
> - case REQ_OP_DISCARD:
> - case REQ_OP_SECURE_ERASE:
> - case REQ_OP_WRITE_SAME:
> - case REQ_OP_WRITE_ZEROES:
> - r = true;
> - break;
> - }
> -
> - return r;
> -}
> -
> static bool __process_abnormal_io(struct clone_info *ci, struct dm_target
> *ti,
> int *result)
> {
> @@ -1723,23 +1707,6 @@ static blk_qc_t __process_bio(struct mapped_device
> *md, struct dm_table *map,
> return ret;
> }
>
> -static void dm_queue_split(struct mapped_device *md, struct dm_target *ti,
> struct bio **bio)
> -{
> - unsigned len, sector_count;
> -
> - sector_count = bio_sectors(*bio);
> - len = min_t(sector_t, max_io_len((*bio)->bi_iter.bi_sector, ti),
> sector_count);
> -
> - if (sector_count > len) {
> - struct bio *split = bio_split(*bio, len, GFP_NOIO,
> &md->queue->bio_split);
> -
> - bio_chain(split, *bio);
> - trace_block_split(md->queue, split, (*bio)->bi_iter.bi_sector);
> - submit_bio_noacct(*bio);
> - *bio = split;
> - }
> -}
> -
> static blk_qc_t dm_process_bio(struct mapped_device *md,
> struct dm_table *map, struct bio *bio)
> {
> @@ -1759,17 +1726,7 @@ static blk_qc_t dm_process_bio(struct mapped_device
> *md,
> }
> }
>
> - /*
> - * If in ->queue_bio we need to use blk_queue_split(), otherwise
> - * queue_limits for abnormal requests (e.g. discard, writesame, etc)
> - * won't be imposed.
> - */
> - if (current->bio_list) {
> - if (is_abnormal_io(bio))
> - blk_queue_split(&bio);
> - else
> - dm_queue_split(md, ti, &bio);
> - }
> + blk_queue_split(&bio);
In max_io_len(), target boundary is taken into account when figuring out
the max io len. However, this info won't be used any more after
switching to blk_queue_split(). Is that one potential problem?
thanks,
Ming
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