Currently target io's reference counter is grabbed before calling __map_bio(), this way isn't efficient since we can move this grabbing into alloc_io().
Meantime it becomes typical async io reference counter model: one is for submission side, the other is for completion side, and the io won't be completed until both two sides are done. Signed-off-by: Ming Lei <[email protected]> --- drivers/md/dm.c | 36 +++++++++++++++++++++++++----------- 1 file changed, 25 insertions(+), 11 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index b8424a4b4725..528559ca2f91 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -579,7 +579,9 @@ static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio) io = container_of(tio, struct dm_io, tio); io->magic = DM_IO_MAGIC; io->status = 0; - atomic_set(&io->io_count, 1); + + /* one is for submission, the other is for completion */ + atomic_set(&io->io_count, 2); this_cpu_inc(*md->pending_io); io->orig_bio = NULL; io->md = md; @@ -929,11 +931,6 @@ static inline bool dm_tio_is_normal(struct dm_target_io *tio) !dm_tio_flagged(tio, DM_TIO_IS_DUPLICATE_BIO)); } -static void dm_io_inc_pending(struct dm_io *io) -{ - atomic_inc(&io->io_count); -} - /* * Decrements the number of outstanding ios that a bio has been * cloned into, completing the original io if necc. @@ -1275,7 +1272,6 @@ static void __map_bio(struct bio *clone) /* * Map the clone. */ - dm_io_inc_pending(io); tio->old_sector = clone->bi_iter.bi_sector; if (unlikely(swap_bios_limit(ti, clone))) { @@ -1357,11 +1353,12 @@ static void alloc_multiple_bios(struct bio_list *blist, struct clone_info *ci, } } -static void __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti, +static int __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti, unsigned num_bios, unsigned *len) { struct bio_list blist = BIO_EMPTY_LIST; struct bio *clone; + int ret = 0; switch (num_bios) { case 0: @@ -1370,15 +1367,19 @@ static void __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti, clone = alloc_tio(ci, ti, 0, len, GFP_NOIO); dm_tio_set_flag(clone_to_tio(clone), DM_TIO_IS_DUPLICATE_BIO); __map_bio(clone); + ret = 1; break; default: alloc_multiple_bios(&blist, ci, ti, num_bios, len); while ((clone = bio_list_pop(&blist))) { dm_tio_set_flag(clone_to_tio(clone), DM_TIO_IS_DUPLICATE_BIO); __map_bio(clone); + ret += 1; } break; } + + return ret; } static void __send_empty_flush(struct clone_info *ci) @@ -1398,8 +1399,16 @@ static void __send_empty_flush(struct clone_info *ci) ci->bio = &flush_bio; ci->sector_count = 0; - while ((ti = dm_table_get_target(ci->map, target_nr++))) - __send_duplicate_bios(ci, ti, ti->num_flush_bios, NULL); + while ((ti = dm_table_get_target(ci->map, target_nr++))) { + int bios; + + atomic_add(ti->num_flush_bios, &ci->io->io_count); + bios = __send_duplicate_bios(ci, ti, ti->num_flush_bios, NULL); + atomic_sub(ti->num_flush_bios - bios, &ci->io->io_count); + } + + /* alloc_io() takes one extra reference for submission */ + atomic_sub(1, &ci->io->io_count); bio_uninit(ci->bio); } @@ -1408,6 +1417,7 @@ static void __send_changing_extent_only(struct clone_info *ci, struct dm_target unsigned num_bios) { unsigned len; + int bios; len = min_t(sector_t, ci->sector_count, max_io_len_target_boundary(ti, dm_target_offset(ti, ci->sector))); @@ -1419,7 +1429,11 @@ static void __send_changing_extent_only(struct clone_info *ci, struct dm_target ci->sector += len; ci->sector_count -= len; - __send_duplicate_bios(ci, ti, num_bios, &len); + + atomic_add(num_bios, &ci->io->io_count); + bios = __send_duplicate_bios(ci, ti, num_bios, &len); + /* alloc_io() takes one extra reference for submission */ + atomic_sub(num_bios - bios + 1, &ci->io->io_count); } static bool is_abnormal_io(struct bio *bio) -- 2.31.1 -- dm-devel mailing list [email protected] https://listman.redhat.com/mailman/listinfo/dm-devel
