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List:       linux-ext4
Subject:    Re: [PATCH] ext4: add sysfs attr /sys/fs/ext4/<disk>/journal_task
From:       "Theodore Y. Ts'o" <tytso () mit ! edu>
Date:       2019-02-21 16:52:58
Message-ID: 20190221165258.GE10245 () mit ! edu
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On Mon, Feb 04, 2019 at 01:17:43PM +0300, Konstantin Khlebnikov wrote:
> This is useful for moving journal thread into cgroup or
> for tracing it with ftrace/perf/blktrace.
> 
> For now the only way is `pgrep jbd2/$DISK` but this is not reliable:
> name may be longer than "comm" limit and any task could mock it.
> 
> Attribute shows pid in current pid-namespace or 0 if task is unreachable.
> 
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>

Thanks, applied with one change; if the file system does not have a
journal, reading the /sys/fs/ext4/<disk>/journal_task will return
"<none>" instead of returning a ESRCH error.

	 	    	      	      - Ted
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