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bcache: do not mark writeback_running too early
[ Upstream commit 79b791466e
]
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>
This commit is contained in:
parent
6f48e23888
commit
b2d84967f0
1 changed files with 2 additions and 1 deletions
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@ -781,7 +781,7 @@ void bch_cached_dev_writeback_init(struct cached_dev *dc)
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bch_keybuf_init(&dc->writeback_keys);
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dc->writeback_metadata = true;
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dc->writeback_running = true;
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dc->writeback_running = false;
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dc->writeback_percent = 10;
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dc->writeback_delay = 30;
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atomic_long_set(&dc->writeback_rate.rate, 1024);
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@ -810,6 +810,7 @@ int bch_cached_dev_writeback_start(struct cached_dev *dc)
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destroy_workqueue(dc->writeback_write_wq);
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return PTR_ERR(dc->writeback_thread);
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}
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dc->writeback_running = true;
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WARN_ON(test_and_set_bit(BCACHE_DEV_WB_RUNNING, &dc->disk.flags));
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schedule_delayed_work(&dc->writeback_rate_update,
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