From cdd4d7832d51e0414472eb2863b294b783597e5e Mon Sep 17 00:00:00 2001
From: Mike Snitzer <snitzer@redhat.com>
Date: Mon, 12 Jul 2021 16:47:15 -0400
Subject: [PATCH] dm writecache: split up writecache_map() to improve code
readability
Git-commit: cdd4d7832d51e0414472eb2863b294b783597e5e
Patch-mainline: v5.15-rc1
References: jsc#PED-2765
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>
Signed-off-by: Coly Li <colyli@suse.de>
---
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 3d2cf811ec3e..53076c7f4a34 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)
--
2.35.3