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authorKonstantin Khlebnikov <khlebnikov@yandex-team.ru>2019-02-21 11:49:27 -0500
committerTheodore Ts'o <tytso@mit.edu>2019-02-21 11:49:27 -0500
commitbc1d69d6151f1911ecb120a8dbd65e47210b7a72 (patch)
tree894a447e6f9669653f4668ab3f791534d6b5f460 /Documentation/ABI
parent231fe82b5609c5d679f81073739c6132aaf166ea (diff)
ext4: add sysfs attr /sys/fs/ext4/<disk>/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 <khlebnikov@yandex-team.ru> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'Documentation/ABI')
-rw-r--r--Documentation/ABI/testing/sysfs-fs-ext47
1 files changed, 7 insertions, 0 deletions
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/<disk>/journal_task
+Date: February 2019
+Contact: "Theodore Ts'o" <tytso@mit.edu>
+Description:
+ This file is read-only and shows the pid of journal thread in
+ current pid-namespace or 0 if task is unreachable.