From bc1d69d6151f1911ecb120a8dbd65e47210b7a72 Mon Sep 17 00:00:00 2001 From: Konstantin Khlebnikov Date: Thu, 21 Feb 2019 11:49:27 -0500 Subject: ext4: add sysfs attr /sys/fs/ext4//journal_task 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 Signed-off-by: Theodore Ts'o --- Documentation/ABI/testing/sysfs-fs-ext4 | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'Documentation/ABI') diff --git a/Documentation/ABI/testing/sysfs-fs-ext4 b/Documentation/ABI/testing/sysfs-fs-ext4 index c631253cf85c..78604db56279 100644 --- a/Documentation/ABI/testing/sysfs-fs-ext4 +++ b/Documentation/ABI/testing/sysfs-fs-ext4 @@ -109,3 +109,10 @@ Description: write operation (since a 4k random write might turn into a much larger write due to the zeroout operation). + +What: /sys/fs/ext4//journal_task +Date: February 2019 +Contact: "Theodore Ts'o" +Description: + This file is read-only and shows the pid of journal thread in + current pid-namespace or 0 if task is unreachable. -- cgit v1.2.3-70-g09d2