block: use standard blktrace API to output cgroup info for debug notes

Currently cfq/bfq/blk-throttle output cgroup info in trace in their own
way. Now we have standard blktrace API for this, so convert them to use
it.

Note, this changes the behavior a little bit. cgroup info isn't output
by default, we only do this with 'blk_cgroup' option enabled. cgroup
info isn't output as a string by default too, we only do this with
'blk_cgname' option enabled. Also cgroup info is output in different
position of the note string. I think these behavior changes aren't a big
issue (actually we make trace data shorter which is good), since the
blktrace note is solely for debugging.

Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 10 insertions, 2 deletions

diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index e90974ed4532..7724de18d2fe 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -154,7 +154,8 @@ static void trace_note_time(struct blk_trace *bt)
         local_irq_restore(flags);
 }
 
-void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
+void __trace_note_message(struct blk_trace *bt, struct blkcg *blkcg,
+        const char *fmt, ...)
 {
         int n;
         va_list args;
@@ -178,7 +179,14 @@ void __trace_note_message(struct blk_trace *bt, const char *fmt, ...)
         n = vscnprintf(buf, BLK_TN_MAX_MSG, fmt, args);
         va_end(args);
 
+        if (!(blk_tracer_flags.val & TRACE_BLK_OPT_CGROUP))
+                blkcg = NULL;
+#ifdef CONFIG_BLK_CGROUP
+        trace_note(bt, 0, BLK_TN_MESSAGE, buf, n,
+                blkcg ? cgroup_get_kernfs_id(blkcg->css.cgroup) : NULL);
+#else
         trace_note(bt, 0, BLK_TN_MESSAGE, buf, n, NULL);
+#endif
         local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(__trace_note_message);
@@ -375,7 +383,7 @@ static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,
                 return PTR_ERR(msg);
 
         bt = filp->private_data;
-        __trace_note_message(bt, "%s", msg);
+        __trace_note_message(bt, NULL, "%s", msg);
         kfree(msg);
 
         return count;