A fresh backing device is not attached to any cache_set, and
has no writeback kthread created until first attached to some
cache_set.
But bch_cached_dev_writeback_init run
"
dc->writeback_running = true;
WARN_ON(test_and_clear_bit(BCACHE_DEV_WB_RUNNING,
&dc->disk.flags));
"
for any newly formatted backing devices.
For a fresh standalone backing device, we can get something like
following even if no writeback kthread created:
------------------------
/sys/block/bcache0/bcache$ cat writeback_rate_debug
rate: 512.0k/sec
dirty: 0.0k
target: 0.0k
proportional: 0.0k
integral: 0.0k
change: 0.0k/sec
next io: -15427384ms
/sys/block/bcache0/bcache$ cat writeback_running
1
Besides that, "echo 1 > writeback_running" will mark writeback_running
when no writeback kthread created as "d_strtoul(writeback_running)" will
simply set dc->writeback_running without checking the existence of
dc->writeback_thread.
This patch fixes above 2 issues: for a fresh standalone backing device,
* dc->writeback_running is set to false, until attached to cache_set.
* "echo 1 > writeback_running" will not mark writeback_running.
Signed-off-by: Shenghui Wang <shhuiw@xxxxxxxxxxx>
---
drivers/md/bcache/writeback.c | 2 +-
drivers/md/bcache/writeback.h | 5 ++++-
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index 08c3a9f9676c..2443621d07d6 100644
--- a/drivers/md/bcache/writeback.c
+++ b/drivers/md/bcache/writeback.c
@@ -777,7 +777,7 @@ void bch_cached_dev_writeback_init(struct cached_dev *dc)
bch_keybuf_init(&dc->writeback_keys);
dc->writeback_metadata = true;
- dc->writeback_running = true;
+ dc->writeback_running = false;
dc->writeback_percent = 10;
dc->writeback_delay = 30;
atomic_long_set(&dc->writeback_rate.rate, 1024);
diff --git a/drivers/md/bcache/writeback.h b/drivers/md/bcache/writeback.h
index d2b9fdbc8994..0601fe1b40f4 100644
--- a/drivers/md/bcache/writeback.h
+++ b/drivers/md/bcache/writeback.h
@@ -78,8 +78,11 @@ static inline bool should_writeback(struct cached_dev *dc, struct bio *bio,
static inline void bch_writeback_queue(struct cached_dev *dc)
{
- if (!IS_ERR_OR_NULL(dc->writeback_thread))
+ if (!IS_ERR_OR_NULL(dc->writeback_thread)) {
wake_up_process(dc->writeback_thread);
+ dc->writeback_running = true;
+ } else
+ dc->writeback_running = false;
}
static inline void bch_writeback_add(struct cached_dev *dc)
--
2.18.0
