Remove double removal of blktrace directory

Remove double removal of blktrace directory

commit fd51d251e4cdb21f68e9dbc4336514d64a105a79

Author: Stefan Raspl <[email protected]>
Date:   Tue May 19 09:59:08 2009 +0200

blktrace: remove debugfs entries on bad path

added in an explicit invocation of debugfs_remove for bt->dir, in blk_remove_buf_file_callback we are also getting the directory removed. On occasion I am seeing memory corruption that I have bisected down to this commit. [The testing involves a (long) series of I/O benchmarks with blktrace invoked around the actual runs.] I believe that this committed patch is correct, but the problem actually lies in the code in blk_remove_buf_file_callback.

With this patch I am able to consistently get complete runs whereas previously I could not get a single run to complete.

The first part of the patch simply moves the debugfs_remove below the
relay_close: the relay_close call will remove files under bt->dir, and so we should not remove the directory until all the files we created have been removed. (Note: This is not sufficient to fix the problem - the file system code has ref counts on the directoy, so our invocation does not cause the directory to actually be removed. Nonetheless, we should not rely upon that feature.)

---
 kernel/trace/blktrace.c |   12 +-----------
 1 files changed, 1 insertions(+), 11 deletions(-)

index 1090b0a..7a34cb5 100644
@@ -267,8 +267,8 @@ static void blk_trace_free(struct blk_trace *bt)
 {
 	debugfs_remove(bt->msg_file);
 	debugfs_remove(bt->dropped_file);
-	debugfs_remove(bt->dir);
 	relay_close(bt->rchan);
+	debugfs_remove(bt->dir);
 	free_percpu(bt->sequence);
 	free_percpu(bt->msg_data);
 	kfree(bt);

@@ -378,18 +378,8 @@ static int blk_subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
 
 static int blk_remove_buf_file_callback(struct dentry *dentry)
 {
-	struct dentry *parent = dentry->d_parent;
 	debugfs_remove(dentry);
 
-	/*
-	* this will fail for all but the last file, but that is ok. what we
-	* care about is the top level buts->name directory going away, when
-	* the last trace file is gone. Then we don't have to rmdir() that
-	* manually on trace stop, so it nicely solves the issue with
-	* force killing of running traces.
-	*/
-
-	debugfs_remove(parent);
 	return 0;
 }
 

1.6.0.4