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| author | Konstantin Khlebnikov <khlebnikov@yandex-team.ru> | 2019-02-21 17:49:27 +0100 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2019-02-21 17:49:27 +0100 |
| commit | bc1d69d6151f1911ecb120a8dbd65e47210b7a72 (patch) | |
| tree | 894a447e6f9669653f4668ab3f791534d6b5f460 /fs/ext4 | |
| parent | ext4: Change debugging support help prefix from EXT4 to Ext4 (diff) | |
| download | linux-bc1d69d6151f1911ecb120a8dbd65e47210b7a72.tar.xz linux-bc1d69d6151f1911ecb120a8dbd65e47210b7a72.zip | |
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 'fs/ext4')
| -rw-r--r-- | fs/ext4/sysfs.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c index 9212a026a1f1..1748e6362d97 100644 --- a/fs/ext4/sysfs.c +++ b/fs/ext4/sysfs.c @@ -30,6 +30,7 @@ typedef enum { attr_feature, attr_pointer_ui, attr_pointer_atomic, + attr_journal_task, } attr_id_t; typedef enum { @@ -125,6 +126,14 @@ static ssize_t trigger_test_error(struct ext4_sb_info *sbi, return count; } +static ssize_t journal_task_show(struct ext4_sb_info *sbi, char *buf) +{ + if (!sbi->s_journal) + return snprintf(buf, PAGE_SIZE, "<none>\n"); + return snprintf(buf, PAGE_SIZE, "%d\n", + task_pid_vnr(sbi->s_journal->j_task)); +} + #define EXT4_ATTR(_name,_mode,_id) \ static struct ext4_attr ext4_attr_##_name = { \ .attr = {.name = __stringify(_name), .mode = _mode }, \ @@ -188,6 +197,7 @@ EXT4_RW_ATTR_SBI_UI(msg_ratelimit_burst, s_msg_ratelimit_state.burst); EXT4_RO_ATTR_ES_UI(errors_count, s_error_count); EXT4_ATTR(first_error_time, 0444, first_error_time); EXT4_ATTR(last_error_time, 0444, last_error_time); +EXT4_ATTR(journal_task, 0444, journal_task); static unsigned int old_bump_val = 128; EXT4_ATTR_PTR(max_writeback_mb_bump, 0444, pointer_ui, &old_bump_val); @@ -217,6 +227,7 @@ static struct attribute *ext4_attrs[] = { ATTR_LIST(errors_count), ATTR_LIST(first_error_time), ATTR_LIST(last_error_time), + ATTR_LIST(journal_task), NULL, }; @@ -304,6 +315,8 @@ static ssize_t ext4_attr_show(struct kobject *kobj, return print_tstamp(buf, sbi->s_es, s_first_error_time); case attr_last_error_time: return print_tstamp(buf, sbi->s_es, s_last_error_time); + case attr_journal_task: + return journal_task_show(sbi, buf); } return 0; |