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authorShenghui Wang <shhuiw@foxmail.com>2018-12-13 22:53:50 +0800
committerJens Axboe <axboe@kernel.dk>2018-12-13 08:15:54 -0700
commit79b791466e525c98f6aeee9acf5726e7b27f4231 (patch)
treec8d4fbf1c3623db1a9214b833deb93f19c22fffc /drivers/md/bcache
parent4e361e020e7220fa8fc812acdca4d08814633f49 (diff)
downloadlinux-79b791466e525c98f6aeee9acf5726e7b27f4231.tar.bz2
bcache: do not mark writeback_running too early
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>
Diffstat (limited to 'drivers/md/bcache')
-rw-r--r--drivers/md/bcache/writeback.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c
index 08c3a9f9676c..1696b212ec4e 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);
@@ -805,6 +805,7 @@ int bch_cached_dev_writeback_start(struct cached_dev *dc)
cached_dev_put(dc);
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,