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| author | Shenghui Wang <shhuiw@foxmail.com> | 2018-12-13 22:53:50 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-12-05 09:20:07 +0100 |
| commit | b2d84967f07658bab63e6157bd2758db5cc68c86 (patch) | |
| tree | f671cf4c3340d546074c39d5545866acb0c6a6e9 | |
| parent | 6f48e23888b92cacab7c610a6220429256b348cf (diff) | |
| download | linux-stable-b2d84967f07658bab63e6157bd2758db5cc68c86.tar.gz linux-stable-b2d84967f07658bab63e6157bd2758db5cc68c86.tar.bz2 linux-stable-b2d84967f07658bab63e6157bd2758db5cc68c86.zip | |
bcache: do not mark writeback_running too early
[ Upstream commit 79b791466e525c98f6aeee9acf5726e7b27f4231 ]
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_running
1
/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
The none ZERO fields are misleading as no alive writeback kthread yet.
Set dc->writeback_running false as no writeback thread created in
bch_cached_dev_writeback_init().
We have writeback thread created and woken up in bch_cached_dev_writeback
_start(). Set dc->writeback_running true before bch_writeback_queue()
called, as a writeback thread will check if dc->writeback_running is true
before writing back dirty data, and hung if false detected.
After the change, we can get the following output for a fresh standalone
backing device:
-----------------------
/sys/block/bcache0/bcache$ cat writeback_running
0
/sys/block/bcache0/bcache# cat writeback_rate_debug
rate: 0.0k/sec
dirty: 0.0k
target: 0.0k
proportional: 0.0k
integral: 0.0k
change: 0.0k/sec
next io: 0ms
v1 -> v2:
Set dc->writeback_running before bch_writeback_queue() called,
Signed-off-by: Shenghui Wang <shhuiw@foxmail.com>
Signed-off-by: Coly Li <colyli@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | drivers/md/bcache/writeback.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c index ba5395fd386d..b5fc3c6c7178 100644 --- a/drivers/md/bcache/writeback.c +++ b/drivers/md/bcache/writeback.c @@ -781,7 +781,7 @@ 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); @@ -810,6 +810,7 @@ int bch_cached_dev_writeback_start(struct cached_dev *dc) destroy_workqueue(dc->writeback_write_wq); return PTR_ERR(dc->writeback_thread); } + dc->writeback_running = true; WARN_ON(test_and_set_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags)); schedule_delayed_work(&dc->writeback_rate_update, |