From cdd4d7832d51e0414472eb2863b294b783597e5e Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Mon, 12 Jul 2021 16:47:15 -0400 Subject: [PATCH] dm writecache: split up writecache_map() to improve code readability writecache_map() has grown too large and can be confusing to read given all the goto statements. Signed-off-by: Mike Snitzer --- drivers/md/dm-writecache.c | 338 +++++++++++++++++++++++++-------------------- 1 file changed, 187 insertions(+), 151 deletions(-) diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c index 3d2cf81..53076c7 100644 --- a/drivers/md/dm-writecache.c +++ b/drivers/md/dm-writecache.c @@ -1293,10 +1293,164 @@ static void writecache_offload_bio(struct dm_writecache *wc, struct bio *bio) bio_list_add(&wc->flush_list, bio); } -static int writecache_map(struct dm_target *ti, struct bio *bio) +enum wc_map_op { + WC_MAP_SUBMIT, + WC_MAP_REMAP, + WC_MAP_REMAP_ORIGIN, + WC_MAP_RETURN, + WC_MAP_ERROR, +}; + +static enum wc_map_op writecache_map_read(struct dm_writecache *wc, struct bio *bio) { + enum wc_map_op map_op; struct wc_entry *e; + +read_next_block: + e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING); + if (e && read_original_sector(wc, e) == bio->bi_iter.bi_sector) { + if (WC_MODE_PMEM(wc)) { + bio_copy_block(wc, bio, memory_data(wc, e)); + if (bio->bi_iter.bi_size) + goto read_next_block; + map_op = WC_MAP_SUBMIT; + } else { + dm_accept_partial_bio(bio, wc->block_size >> SECTOR_SHIFT); + bio_set_dev(bio, wc->ssd_dev->bdev); + bio->bi_iter.bi_sector = cache_sector(wc, e); + if (!writecache_entry_is_committed(wc, e)) + writecache_wait_for_ios(wc, WRITE); + map_op = WC_MAP_REMAP; + } + } else { + if (e) { + sector_t next_boundary = + read_original_sector(wc, e) - bio->bi_iter.bi_sector; + if (next_boundary < bio->bi_iter.bi_size >> SECTOR_SHIFT) + dm_accept_partial_bio(bio, next_boundary); + } + map_op = WC_MAP_REMAP_ORIGIN; + } + + return map_op; +} + +static enum wc_map_op writecache_bio_copy_ssd(struct dm_writecache *wc, struct bio *bio, + struct wc_entry *e, bool search_used) +{ + unsigned bio_size = wc->block_size; + sector_t start_cache_sec = cache_sector(wc, e); + sector_t current_cache_sec = start_cache_sec + (bio_size >> SECTOR_SHIFT); + + while (bio_size < bio->bi_iter.bi_size) { + if (!search_used) { + struct wc_entry *f = writecache_pop_from_freelist(wc, current_cache_sec); + if (!f) + break; + write_original_sector_seq_count(wc, f, bio->bi_iter.bi_sector + + (bio_size >> SECTOR_SHIFT), wc->seq_count); + writecache_insert_entry(wc, f); + wc->uncommitted_blocks++; + } else { + struct wc_entry *f; + struct rb_node *next = rb_next(&e->rb_node); + if (!next) + break; + f = container_of(next, struct wc_entry, rb_node); + if (f != e + 1) + break; + if (read_original_sector(wc, f) != + read_original_sector(wc, e) + (wc->block_size >> SECTOR_SHIFT)) + break; + if (unlikely(f->write_in_progress)) + break; + if (writecache_entry_is_committed(wc, f)) + wc->overwrote_committed = true; + e = f; + } + bio_size += wc->block_size; + current_cache_sec += wc->block_size >> SECTOR_SHIFT; + } + + bio_set_dev(bio, wc->ssd_dev->bdev); + bio->bi_iter.bi_sector = start_cache_sec; + dm_accept_partial_bio(bio, bio_size >> SECTOR_SHIFT); + + if (unlikely(wc->uncommitted_blocks >= wc->autocommit_blocks)) { + wc->uncommitted_blocks = 0; + queue_work(wc->writeback_wq, &wc->flush_work); + } else { + writecache_schedule_autocommit(wc); + } + + return WC_MAP_REMAP; +} + +static enum wc_map_op writecache_map_write(struct dm_writecache *wc, struct bio *bio) +{ + struct wc_entry *e; + + do { + bool found_entry = false; + bool search_used = false; + if (writecache_has_error(wc)) + return WC_MAP_ERROR; + e = writecache_find_entry(wc, bio->bi_iter.bi_sector, 0); + if (e) { + if (!writecache_entry_is_committed(wc, e)) { + search_used = true; + goto bio_copy; + } + if (!WC_MODE_PMEM(wc) && !e->write_in_progress) { + wc->overwrote_committed = true; + search_used = true; + goto bio_copy; + } + found_entry = true; + } else { + if (unlikely(wc->cleaner) || + (wc->metadata_only && !(bio->bi_opf & REQ_META))) + goto direct_write; + } + e = writecache_pop_from_freelist(wc, (sector_t)-1); + if (unlikely(!e)) { + if (!WC_MODE_PMEM(wc) && !found_entry) { +direct_write: + e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING); + if (e) { + sector_t next_boundary = read_original_sector(wc, e) - bio->bi_iter.bi_sector; + BUG_ON(!next_boundary); + if (next_boundary < bio->bi_iter.bi_size >> SECTOR_SHIFT) { + dm_accept_partial_bio(bio, next_boundary); + } + } + return WC_MAP_REMAP_ORIGIN; + } + writecache_wait_on_freelist(wc); + continue; + } + write_original_sector_seq_count(wc, e, bio->bi_iter.bi_sector, wc->seq_count); + writecache_insert_entry(wc, e); + wc->uncommitted_blocks++; +bio_copy: + if (WC_MODE_PMEM(wc)) + bio_copy_block(wc, bio, memory_data(wc, e)); + else + return writecache_bio_copy_ssd(wc, bio, e, search_used); + } while (bio->bi_iter.bi_size); + + if (unlikely(bio->bi_opf & REQ_FUA || wc->uncommitted_blocks >= wc->autocommit_blocks)) + writecache_flush(wc); + else + writecache_schedule_autocommit(wc); + + return WC_MAP_SUBMIT; +} + +static int writecache_map(struct dm_target *ti, struct bio *bio) +{ struct dm_writecache *wc = ti->private; + enum wc_map_op map_op = WC_MAP_ERROR; bio->bi_private = NULL; @@ -1342,167 +1496,49 @@ static int writecache_map(struct dm_target *ti, struct bio *bio) } } - if (bio_data_dir(bio) == READ) { -read_next_block: - e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING); - if (e && read_original_sector(wc, e) == bio->bi_iter.bi_sector) { - if (WC_MODE_PMEM(wc)) { - bio_copy_block(wc, bio, memory_data(wc, e)); - if (bio->bi_iter.bi_size) - goto read_next_block; - goto unlock_submit; - } else { - dm_accept_partial_bio(bio, wc->block_size >> SECTOR_SHIFT); - bio_set_dev(bio, wc->ssd_dev->bdev); - bio->bi_iter.bi_sector = cache_sector(wc, e); - if (!writecache_entry_is_committed(wc, e)) - writecache_wait_for_ios(wc, WRITE); - goto unlock_remap; - } - } else { - if (e) { - sector_t next_boundary = - read_original_sector(wc, e) - bio->bi_iter.bi_sector; - if (next_boundary < bio->bi_iter.bi_size >> SECTOR_SHIFT) { - dm_accept_partial_bio(bio, next_boundary); - } - } - goto unlock_remap_origin; - } - } else { - do { - bool found_entry = false; - bool search_used = false; - if (writecache_has_error(wc)) - goto unlock_error; - e = writecache_find_entry(wc, bio->bi_iter.bi_sector, 0); - if (e) { - if (!writecache_entry_is_committed(wc, e)) { - search_used = true; - goto bio_copy; - } - if (!WC_MODE_PMEM(wc) && !e->write_in_progress) { - wc->overwrote_committed = true; - search_used = true; - goto bio_copy; - } - found_entry = true; - } else { - if (unlikely(wc->cleaner) || - (wc->metadata_only && !(bio->bi_opf & REQ_META))) - goto direct_write; - } - e = writecache_pop_from_freelist(wc, (sector_t)-1); - if (unlikely(!e)) { - if (!WC_MODE_PMEM(wc) && !found_entry) { -direct_write: - e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING); - if (e) { - sector_t next_boundary = read_original_sector(wc, e) - bio->bi_iter.bi_sector; - BUG_ON(!next_boundary); - if (next_boundary < bio->bi_iter.bi_size >> SECTOR_SHIFT) { - dm_accept_partial_bio(bio, next_boundary); - } - } - goto unlock_remap_origin; - } - writecache_wait_on_freelist(wc); - continue; - } - write_original_sector_seq_count(wc, e, bio->bi_iter.bi_sector, wc->seq_count); - writecache_insert_entry(wc, e); - wc->uncommitted_blocks++; -bio_copy: - if (WC_MODE_PMEM(wc)) { - bio_copy_block(wc, bio, memory_data(wc, e)); - } else { - unsigned bio_size = wc->block_size; - sector_t start_cache_sec = cache_sector(wc, e); - sector_t current_cache_sec = start_cache_sec + (bio_size >> SECTOR_SHIFT); - - while (bio_size < bio->bi_iter.bi_size) { - if (!search_used) { - struct wc_entry *f = writecache_pop_from_freelist(wc, current_cache_sec); - if (!f) - break; - write_original_sector_seq_count(wc, f, bio->bi_iter.bi_sector + - (bio_size >> SECTOR_SHIFT), wc->seq_count); - writecache_insert_entry(wc, f); - wc->uncommitted_blocks++; - } else { - struct wc_entry *f; - struct rb_node *next = rb_next(&e->rb_node); - if (!next) - break; - f = container_of(next, struct wc_entry, rb_node); - if (f != e + 1) - break; - if (read_original_sector(wc, f) != - read_original_sector(wc, e) + (wc->block_size >> SECTOR_SHIFT)) - break; - if (unlikely(f->write_in_progress)) - break; - if (writecache_entry_is_committed(wc, f)) - wc->overwrote_committed = true; - e = f; - } - bio_size += wc->block_size; - current_cache_sec += wc->block_size >> SECTOR_SHIFT; - } - - bio_set_dev(bio, wc->ssd_dev->bdev); - bio->bi_iter.bi_sector = start_cache_sec; - dm_accept_partial_bio(bio, bio_size >> SECTOR_SHIFT); - - if (unlikely(wc->uncommitted_blocks >= wc->autocommit_blocks)) { - wc->uncommitted_blocks = 0; - queue_work(wc->writeback_wq, &wc->flush_work); - } else { - writecache_schedule_autocommit(wc); - } - goto unlock_remap; - } - } while (bio->bi_iter.bi_size); - - if (unlikely(bio->bi_opf & REQ_FUA || - wc->uncommitted_blocks >= wc->autocommit_blocks)) - writecache_flush(wc); - else - writecache_schedule_autocommit(wc); - goto unlock_submit; - } + if (bio_data_dir(bio) == READ) + map_op = writecache_map_read(wc, bio); + else + map_op = writecache_map_write(wc, bio); + switch (map_op) { + case WC_MAP_REMAP_ORIGIN: unlock_remap_origin: - if (likely(wc->pause != 0)) { - if (bio_op(bio) == REQ_OP_WRITE) { - dm_iot_io_begin(&wc->iot, 1); - bio->bi_private = (void *)2; + if (likely(wc->pause != 0)) { + if (bio_op(bio) == REQ_OP_WRITE) { + dm_iot_io_begin(&wc->iot, 1); + bio->bi_private = (void *)2; + } } - } - bio_set_dev(bio, wc->dev->bdev); - wc_unlock(wc); - return DM_MAPIO_REMAPPED; + bio_set_dev(bio, wc->dev->bdev); + wc_unlock(wc); + return DM_MAPIO_REMAPPED; + case WC_MAP_REMAP: unlock_remap: - /* make sure that writecache_end_io decrements bio_in_progress: */ - bio->bi_private = (void *)1; - atomic_inc(&wc->bio_in_progress[bio_data_dir(bio)]); - wc_unlock(wc); - return DM_MAPIO_REMAPPED; + /* make sure that writecache_end_io decrements bio_in_progress: */ + bio->bi_private = (void *)1; + atomic_inc(&wc->bio_in_progress[bio_data_dir(bio)]); + wc_unlock(wc); + return DM_MAPIO_REMAPPED; + case WC_MAP_SUBMIT: unlock_submit: - wc_unlock(wc); - bio_endio(bio); - return DM_MAPIO_SUBMITTED; + wc_unlock(wc); + bio_endio(bio); + return DM_MAPIO_SUBMITTED; + case WC_MAP_RETURN: unlock_return: - wc_unlock(wc); - return DM_MAPIO_SUBMITTED; + wc_unlock(wc); + return DM_MAPIO_SUBMITTED; + case WC_MAP_ERROR: unlock_error: - wc_unlock(wc); - bio_io_error(bio); - return DM_MAPIO_SUBMITTED; + wc_unlock(wc); + bio_io_error(bio); + return DM_MAPIO_SUBMITTED; + } } static int writecache_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *status) -- 2.7.4