From 6ac93117ab009d3901ed5d3d0f79056eb5fc0afd Mon Sep 17 00:00:00 2001
From: Omar Sandoval <osandov@fb.com>
Date: Tue, 31 Jan 2017 14:53:22 -0800
Subject: [PATCH] blktrace: use existing disk debugfs directory
We may already have a directory to put the blktrace stuff in if
1. The disk uses blk-mq
2. CONFIG_BLK_DEBUG_FS is enabled
3. We are tracing the whole disk and not a partition
Instead of hardcoding this very specific case, let's use the new
debugfs_lookup(). If the directory exists, we use it, otherwise we
create one and clean it up later.
Fixes: 07e4fead45e6 ("blk-mq: create debugfs directory tree")
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
---
kernel/trace/blktrace.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 8cea91d248d98..b2058a7f94bd8 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -470,12 +470,12 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
if (!blk_debugfs_root)
goto err;
- dir = debugfs_create_dir(buts->name, blk_debugfs_root);
-
+ dir = debugfs_lookup(buts->name, blk_debugfs_root);
+ if (!dir)
+ bt->dir = dir = debugfs_create_dir(buts->name, blk_debugfs_root);
if (!dir)
goto err;
- bt->dir = dir;
bt->dev = dev;
atomic_set(&bt->dropped, 0);
INIT_LIST_HEAD(&bt->running_list);
@@ -517,9 +517,12 @@ static int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
if (atomic_inc_return(&blk_probes_ref) == 1)
blk_register_tracepoints();
- return 0;
+ ret = 0;
err:
- blk_trace_free(bt);
+ if (dir && !bt->dir)
+ dput(dir);
+ if (ret)
+ blk_trace_free(bt);
return ret;
}