Re: [PATCH] bcache: stop writeback thread after detaching

Tang Junhui--

Thanks for noticing this issue.

On Wed, Nov 1, 2017 at 4:55 AM, Coly Li [off-list ref] wrote:

On 2017/10/31 =E4=B8=8B=E5=8D=884:14, tang.junhui@zte.com.cn wrote:

quoted

From: Tang Junhui <redacted>

Currently, when a cached device detaching from cache, writeback thread i=

s not stopped,

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and writeback_rate_update work is not canceled. For example, after bello=

w command:

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echo 1 >/sys/block/sdb/bcache/detach
you can still see the writeback thread. Then you attach the device to th=

e cache again,

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bcache will create another writeback thread, for example, after bellow c=

ommand:

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echo  ba0fb5cd-658a-4533-9806-6ce166d883b9 > /sys/block/sdb/bcache/attac=

h

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then you will see 2 writeback threads.
This patch stops writeback thread and cancels writeback_rate_update work=

 when cached

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device detaching from cache.

Signed-off-by: Tang Junhui <redacted>

If the change can be inside bch_register_lock, it would (just) be more
comfortable. The code is correct, because attach/detach sysfs is created
after writeback_thread created and writeback_rate_update worker
initialized, even these resources are initialized within
bch_register_lock and released out of bch)register_lock in your patch,
there won't be any race. It's OK to me.

I think I agree with Coly that I'd prefer it to be moved down into the
register lock, as I think that will be safer with any future changes.
Are you willing to adjust it this way?

Thanks,

Mike