After all writeback bios for a kset complete, writeback_ctx_end()
flushes the backing device and then advances the persistent dirty_tail.
However, backing_dev_flush() discards the error returned by
blkdev_issue_flush(), so dirty_tail is advanced even when the written
data is not known to be durable.
dirty_tail points to the first kset that still requires writeback.
Advancing it causes recovery to treat the preceding kset as clean and
allows its cache copy to eventually be reclaimed by garbage collection.
If the backing device flush failed, a subsequent power failure may
therefore result in data loss.
Make backing_dev_flush() return the flush status and handle a flush
failure like a writeback I/O failure. Leave dirty_tail unchanged so
that the same kset will be retried.
Fixes: 1d57628ff95b ("dm-pcache: add persistent cache target in device-mapper")
Cc: [email protected]
Signed-off-by: guolingxing <[email protected]>
---
drivers/md/dm-pcache/backing_dev.c | 4 ++--
drivers/md/dm-pcache/backing_dev.h | 2 +-
drivers/md/dm-pcache/cache_writeback.c | 28 +++++++++++++++++++-------
3 files changed, 24 insertions(+), 10 deletions(-)
diff --git a/drivers/md/dm-pcache/backing_dev.c
b/drivers/md/dm-pcache/backing_dev.c
index 7165fc0364bb..0c15bb01068e 100644
--- a/drivers/md/dm-pcache/backing_dev.c
+++ b/drivers/md/dm-pcache/backing_dev.c
@@ -336,9 +336,9 @@ struct pcache_backing_dev_req
*backing_dev_req_create(struct pcache_backing_dev
return backing_req;
}
-void backing_dev_flush(struct pcache_backing_dev *backing_dev)
+int backing_dev_flush(struct pcache_backing_dev *backing_dev)
{
- blkdev_issue_flush(backing_dev->dm_dev->bdev);
+ return blkdev_issue_flush(backing_dev->dm_dev->bdev);
}
int pcache_backing_init(void)
diff --git a/drivers/md/dm-pcache/backing_dev.h
b/drivers/md/dm-pcache/backing_dev.h
index b371cba483b9..8422e5e76e29 100644
--- a/drivers/md/dm-pcache/backing_dev.h
+++ b/drivers/md/dm-pcache/backing_dev.h
@@ -120,7 +120,7 @@ struct pcache_backing_dev_req *backing_dev_req_alloc(struct
pcache_backing_dev *
struct
pcache_backing_dev_req_opts *opts);
void backing_dev_req_init(struct pcache_backing_dev_req *backing_req,
struct pcache_backing_dev_req_opts *opts);
-void backing_dev_flush(struct pcache_backing_dev *backing_dev);
+int backing_dev_flush(struct pcache_backing_dev *backing_dev);
int pcache_backing_init(void);
void pcache_backing_exit(void);
diff --git a/drivers/md/dm-pcache/cache_writeback.c
b/drivers/md/dm-pcache/cache_writeback.c
index c8a4c8110a58..e09560f172dd 100644
--- a/drivers/md/dm-pcache/cache_writeback.c
+++ b/drivers/md/dm-pcache/cache_writeback.c
@@ -18,12 +18,18 @@ static void writeback_ctx_end(struct pcache_cache *cache,
int ret)
return;
if (!cache->writeback_ctx.ret) {
- backing_dev_flush(cache->backing_dev);
-
- mutex_lock(&cache->dirty_tail_lock);
- cache_pos_advance(&cache->dirty_tail,
cache->writeback_ctx.advance);
- cache_encode_dirty_tail(cache);
- mutex_unlock(&cache->dirty_tail_lock);
+ ret = backing_dev_flush(cache->backing_dev);
+ if (ret) {
+ pcache_dev_err(CACHE_TO_PCACHE(cache),
+ "failed to flush backing device: %d",
ret);
+ cache->writeback_ctx.ret = ret;
+ } else {
+ mutex_lock(&cache->dirty_tail_lock);
+ cache_pos_advance(&cache->dirty_tail,
+ cache->writeback_ctx.advance);
+ cache_encode_dirty_tail(cache);
+ mutex_unlock(&cache->dirty_tail_lock);
+ }
}
queue_delayed_work(cache_get_wq(cache), &cache->writeback_work, 0);
}
@@ -76,8 +82,16 @@ static inline bool is_cache_clean(struct pcache_cache
*cache, struct pcache_cach
void cache_writeback_exit(struct pcache_cache *cache)
{
+ int ret;
+
cancel_delayed_work_sync(&cache->writeback_work);
- backing_dev_flush(cache->backing_dev);
+
+ ret = backing_dev_flush(cache->backing_dev);
+ if (ret)
+ pcache_dev_err(CACHE_TO_PCACHE(cache),
+ "failed to flush backing device during exit: %d",
+ ret);
+
cache_tree_exit(&cache->writeback_key_tree);
}
--
2.34.1
