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 <snitzer@redhat.com>
This commit is contained in:
Mike Snitzer
parent
99d26de2f6
commit
cdd4d7832d
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@ -1293,10 +1293,164 @@ static void writecache_offload_bio(struct dm_writecache *wc, struct bio *bio)
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bio_list_add(&wc->flush_list, bio);
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}
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static int writecache_map(struct dm_target *ti, struct bio *bio)
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enum wc_map_op {
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WC_MAP_SUBMIT,
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WC_MAP_REMAP,
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WC_MAP_REMAP_ORIGIN,
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WC_MAP_RETURN,
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WC_MAP_ERROR,
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};
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static enum wc_map_op writecache_map_read(struct dm_writecache *wc, struct bio *bio)
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{
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enum wc_map_op map_op;
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struct wc_entry *e;
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read_next_block:
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e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING);
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if (e && read_original_sector(wc, e) == bio->bi_iter.bi_sector) {
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if (WC_MODE_PMEM(wc)) {
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bio_copy_block(wc, bio, memory_data(wc, e));
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if (bio->bi_iter.bi_size)
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goto read_next_block;
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map_op = WC_MAP_SUBMIT;
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} else {
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dm_accept_partial_bio(bio, wc->block_size >> SECTOR_SHIFT);
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bio_set_dev(bio, wc->ssd_dev->bdev);
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bio->bi_iter.bi_sector = cache_sector(wc, e);
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if (!writecache_entry_is_committed(wc, e))
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writecache_wait_for_ios(wc, WRITE);
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map_op = WC_MAP_REMAP;
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}
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} else {
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if (e) {
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sector_t next_boundary =
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read_original_sector(wc, e) - bio->bi_iter.bi_sector;
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if (next_boundary < bio->bi_iter.bi_size >> SECTOR_SHIFT)
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dm_accept_partial_bio(bio, next_boundary);
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}
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map_op = WC_MAP_REMAP_ORIGIN;
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}
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return map_op;
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}
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static enum wc_map_op writecache_bio_copy_ssd(struct dm_writecache *wc, struct bio *bio,
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struct wc_entry *e, bool search_used)
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{
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unsigned bio_size = wc->block_size;
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sector_t start_cache_sec = cache_sector(wc, e);
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sector_t current_cache_sec = start_cache_sec + (bio_size >> SECTOR_SHIFT);
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while (bio_size < bio->bi_iter.bi_size) {
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if (!search_used) {
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struct wc_entry *f = writecache_pop_from_freelist(wc, current_cache_sec);
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if (!f)
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break;
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write_original_sector_seq_count(wc, f, bio->bi_iter.bi_sector +
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(bio_size >> SECTOR_SHIFT), wc->seq_count);
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writecache_insert_entry(wc, f);
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wc->uncommitted_blocks++;
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} else {
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struct wc_entry *f;
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struct rb_node *next = rb_next(&e->rb_node);
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if (!next)
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break;
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f = container_of(next, struct wc_entry, rb_node);
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if (f != e + 1)
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break;
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if (read_original_sector(wc, f) !=
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read_original_sector(wc, e) + (wc->block_size >> SECTOR_SHIFT))
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break;
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if (unlikely(f->write_in_progress))
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break;
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if (writecache_entry_is_committed(wc, f))
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wc->overwrote_committed = true;
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e = f;
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}
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bio_size += wc->block_size;
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current_cache_sec += wc->block_size >> SECTOR_SHIFT;
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}
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bio_set_dev(bio, wc->ssd_dev->bdev);
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bio->bi_iter.bi_sector = start_cache_sec;
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dm_accept_partial_bio(bio, bio_size >> SECTOR_SHIFT);
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if (unlikely(wc->uncommitted_blocks >= wc->autocommit_blocks)) {
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wc->uncommitted_blocks = 0;
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queue_work(wc->writeback_wq, &wc->flush_work);
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} else {
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writecache_schedule_autocommit(wc);
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}
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return WC_MAP_REMAP;
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}
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static enum wc_map_op writecache_map_write(struct dm_writecache *wc, struct bio *bio)
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{
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struct wc_entry *e;
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do {
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bool found_entry = false;
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bool search_used = false;
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if (writecache_has_error(wc))
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return WC_MAP_ERROR;
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e = writecache_find_entry(wc, bio->bi_iter.bi_sector, 0);
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if (e) {
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if (!writecache_entry_is_committed(wc, e)) {
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search_used = true;
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goto bio_copy;
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}
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if (!WC_MODE_PMEM(wc) && !e->write_in_progress) {
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wc->overwrote_committed = true;
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search_used = true;
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goto bio_copy;
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}
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found_entry = true;
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} else {
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if (unlikely(wc->cleaner) ||
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(wc->metadata_only && !(bio->bi_opf & REQ_META)))
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goto direct_write;
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}
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e = writecache_pop_from_freelist(wc, (sector_t)-1);
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if (unlikely(!e)) {
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if (!WC_MODE_PMEM(wc) && !found_entry) {
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direct_write:
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e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING);
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if (e) {
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sector_t next_boundary = read_original_sector(wc, e) - bio->bi_iter.bi_sector;
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BUG_ON(!next_boundary);
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if (next_boundary < bio->bi_iter.bi_size >> SECTOR_SHIFT) {
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dm_accept_partial_bio(bio, next_boundary);
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}
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}
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return WC_MAP_REMAP_ORIGIN;
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}
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writecache_wait_on_freelist(wc);
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continue;
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}
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write_original_sector_seq_count(wc, e, bio->bi_iter.bi_sector, wc->seq_count);
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writecache_insert_entry(wc, e);
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wc->uncommitted_blocks++;
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bio_copy:
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if (WC_MODE_PMEM(wc))
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bio_copy_block(wc, bio, memory_data(wc, e));
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else
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return writecache_bio_copy_ssd(wc, bio, e, search_used);
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} while (bio->bi_iter.bi_size);
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if (unlikely(bio->bi_opf & REQ_FUA || wc->uncommitted_blocks >= wc->autocommit_blocks))
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writecache_flush(wc);
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else
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writecache_schedule_autocommit(wc);
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return WC_MAP_SUBMIT;
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}
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static int writecache_map(struct dm_target *ti, struct bio *bio)
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{
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struct dm_writecache *wc = ti->private;
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enum wc_map_op map_op = WC_MAP_ERROR;
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bio->bi_private = NULL;
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@ -1342,167 +1496,49 @@ static int writecache_map(struct dm_target *ti, struct bio *bio)
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}
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}
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if (bio_data_dir(bio) == READ) {
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read_next_block:
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e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING);
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if (e && read_original_sector(wc, e) == bio->bi_iter.bi_sector) {
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if (WC_MODE_PMEM(wc)) {
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bio_copy_block(wc, bio, memory_data(wc, e));
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if (bio->bi_iter.bi_size)
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goto read_next_block;
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goto unlock_submit;
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} else {
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dm_accept_partial_bio(bio, wc->block_size >> SECTOR_SHIFT);
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bio_set_dev(bio, wc->ssd_dev->bdev);
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bio->bi_iter.bi_sector = cache_sector(wc, e);
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if (!writecache_entry_is_committed(wc, e))
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writecache_wait_for_ios(wc, WRITE);
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goto unlock_remap;
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}
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} else {
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if (e) {
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sector_t next_boundary =
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read_original_sector(wc, e) - bio->bi_iter.bi_sector;
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if (next_boundary < bio->bi_iter.bi_size >> SECTOR_SHIFT) {
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dm_accept_partial_bio(bio, next_boundary);
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}
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}
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goto unlock_remap_origin;
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}
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} else {
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do {
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bool found_entry = false;
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bool search_used = false;
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if (writecache_has_error(wc))
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goto unlock_error;
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e = writecache_find_entry(wc, bio->bi_iter.bi_sector, 0);
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if (e) {
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if (!writecache_entry_is_committed(wc, e)) {
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search_used = true;
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goto bio_copy;
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}
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if (!WC_MODE_PMEM(wc) && !e->write_in_progress) {
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wc->overwrote_committed = true;
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search_used = true;
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goto bio_copy;
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}
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found_entry = true;
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} else {
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if (unlikely(wc->cleaner) ||
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(wc->metadata_only && !(bio->bi_opf & REQ_META)))
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goto direct_write;
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}
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e = writecache_pop_from_freelist(wc, (sector_t)-1);
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if (unlikely(!e)) {
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if (!WC_MODE_PMEM(wc) && !found_entry) {
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direct_write:
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e = writecache_find_entry(wc, bio->bi_iter.bi_sector, WFE_RETURN_FOLLOWING);
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if (e) {
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sector_t next_boundary = read_original_sector(wc, e) - bio->bi_iter.bi_sector;
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BUG_ON(!next_boundary);
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if (next_boundary < bio->bi_iter.bi_size >> SECTOR_SHIFT) {
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dm_accept_partial_bio(bio, next_boundary);
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}
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}
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goto unlock_remap_origin;
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}
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writecache_wait_on_freelist(wc);
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continue;
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}
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write_original_sector_seq_count(wc, e, bio->bi_iter.bi_sector, wc->seq_count);
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writecache_insert_entry(wc, e);
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wc->uncommitted_blocks++;
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bio_copy:
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if (WC_MODE_PMEM(wc)) {
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bio_copy_block(wc, bio, memory_data(wc, e));
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} else {
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unsigned bio_size = wc->block_size;
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sector_t start_cache_sec = cache_sector(wc, e);
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sector_t current_cache_sec = start_cache_sec + (bio_size >> SECTOR_SHIFT);
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while (bio_size < bio->bi_iter.bi_size) {
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if (!search_used) {
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struct wc_entry *f = writecache_pop_from_freelist(wc, current_cache_sec);
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if (!f)
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break;
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write_original_sector_seq_count(wc, f, bio->bi_iter.bi_sector +
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(bio_size >> SECTOR_SHIFT), wc->seq_count);
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writecache_insert_entry(wc, f);
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wc->uncommitted_blocks++;
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} else {
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struct wc_entry *f;
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struct rb_node *next = rb_next(&e->rb_node);
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if (!next)
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break;
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f = container_of(next, struct wc_entry, rb_node);
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if (f != e + 1)
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break;
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if (read_original_sector(wc, f) !=
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read_original_sector(wc, e) + (wc->block_size >> SECTOR_SHIFT))
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break;
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if (unlikely(f->write_in_progress))
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break;
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if (writecache_entry_is_committed(wc, f))
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wc->overwrote_committed = true;
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e = f;
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}
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bio_size += wc->block_size;
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current_cache_sec += wc->block_size >> SECTOR_SHIFT;
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}
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bio_set_dev(bio, wc->ssd_dev->bdev);
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bio->bi_iter.bi_sector = start_cache_sec;
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dm_accept_partial_bio(bio, bio_size >> SECTOR_SHIFT);
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if (unlikely(wc->uncommitted_blocks >= wc->autocommit_blocks)) {
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wc->uncommitted_blocks = 0;
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queue_work(wc->writeback_wq, &wc->flush_work);
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} else {
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writecache_schedule_autocommit(wc);
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}
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goto unlock_remap;
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}
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} while (bio->bi_iter.bi_size);
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if (unlikely(bio->bi_opf & REQ_FUA ||
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wc->uncommitted_blocks >= wc->autocommit_blocks))
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writecache_flush(wc);
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else
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writecache_schedule_autocommit(wc);
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goto unlock_submit;
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}
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if (bio_data_dir(bio) == READ)
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map_op = writecache_map_read(wc, bio);
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else
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map_op = writecache_map_write(wc, bio);
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switch (map_op) {
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case WC_MAP_REMAP_ORIGIN:
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unlock_remap_origin:
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if (likely(wc->pause != 0)) {
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if (bio_op(bio) == REQ_OP_WRITE) {
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dm_iot_io_begin(&wc->iot, 1);
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bio->bi_private = (void *)2;
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if (likely(wc->pause != 0)) {
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if (bio_op(bio) == REQ_OP_WRITE) {
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dm_iot_io_begin(&wc->iot, 1);
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bio->bi_private = (void *)2;
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}
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}
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}
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bio_set_dev(bio, wc->dev->bdev);
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wc_unlock(wc);
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return DM_MAPIO_REMAPPED;
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bio_set_dev(bio, wc->dev->bdev);
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wc_unlock(wc);
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return DM_MAPIO_REMAPPED;
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case WC_MAP_REMAP:
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unlock_remap:
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/* make sure that writecache_end_io decrements bio_in_progress: */
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bio->bi_private = (void *)1;
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atomic_inc(&wc->bio_in_progress[bio_data_dir(bio)]);
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wc_unlock(wc);
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return DM_MAPIO_REMAPPED;
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/* make sure that writecache_end_io decrements bio_in_progress: */
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bio->bi_private = (void *)1;
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atomic_inc(&wc->bio_in_progress[bio_data_dir(bio)]);
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wc_unlock(wc);
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return DM_MAPIO_REMAPPED;
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case WC_MAP_SUBMIT:
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unlock_submit:
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wc_unlock(wc);
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bio_endio(bio);
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return DM_MAPIO_SUBMITTED;
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wc_unlock(wc);
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bio_endio(bio);
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return DM_MAPIO_SUBMITTED;
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case WC_MAP_RETURN:
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unlock_return:
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wc_unlock(wc);
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return DM_MAPIO_SUBMITTED;
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wc_unlock(wc);
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return DM_MAPIO_SUBMITTED;
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case WC_MAP_ERROR:
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unlock_error:
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wc_unlock(wc);
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bio_io_error(bio);
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return DM_MAPIO_SUBMITTED;
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wc_unlock(wc);
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bio_io_error(bio);
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return DM_MAPIO_SUBMITTED;
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}
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}
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static int writecache_end_io(struct dm_target *ti, struct bio *bio, blk_status_t *status)
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