Fix oinkmaster patch.

[people/pmueller/ipfire-2.x.git] / src / patches / suse-2.6.27.39 / patches.fixes / block-get-rid-of-the-manual-directory-counting-in-blktrace.patch

From: Jens Axboe <jens.axboe@oracle.com>
Date:   Mon Jan 5 10:17:25 2009 +0100
Subject: block: get rid of the manual directory counting in blktrace
References: bnc#475149
    
    It can result in a stuck blktrace system, if --kill is used.
    
    Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

Acked-by: Jan Blunck <jblunck@suse.de>
---
 block/blktrace.c |   72 ++++++++++++++++---------------------------------------
 1 file changed, 21 insertions(+), 51 deletions(-)

Index: b/block/blktrace.c
===================================================================
--- a/block/blktrace.c
+++ b/block/blktrace.c
@@ -181,59 +181,12 @@ EXPORT_SYMBOL_GPL(__blk_add_trace);
 
 static struct dentry *blk_tree_root;
 static DEFINE_MUTEX(blk_tree_mutex);
-static unsigned int root_users;
-
-static inline void blk_remove_root(void)
-{
-	if (blk_tree_root) {
-		debugfs_remove(blk_tree_root);
-		blk_tree_root = NULL;
-	}
-}
-
-static void blk_remove_tree(struct dentry *dir)
-{
-	mutex_lock(&blk_tree_mutex);
-	debugfs_remove(dir);
-	if (--root_users == 0)
-		blk_remove_root();
-	mutex_unlock(&blk_tree_mutex);
-}
-
-static struct dentry *blk_create_tree(const char *blk_name)
-{
-	struct dentry *dir = NULL;
-	int created = 0;
-
-	mutex_lock(&blk_tree_mutex);
-
-	if (!blk_tree_root) {
-		blk_tree_root = debugfs_create_dir("block", NULL);
-		if (!blk_tree_root)
-			goto err;
-		created = 1;
-	}
-
-	dir = debugfs_create_dir(blk_name, blk_tree_root);
-	if (dir)
-		root_users++;
-	else {
-		/* Delete root only if we created it */
-		if (created)
-			blk_remove_root();
-	}
-
-err:
-	mutex_unlock(&blk_tree_mutex);
-	return dir;
-}
 
 static void blk_trace_cleanup(struct blk_trace *bt)
 {
-	relay_close(bt->rchan);
 	debugfs_remove(bt->msg_file);
 	debugfs_remove(bt->dropped_file);
-	blk_remove_tree(bt->dir);
+	relay_close(bt->rchan);
 	free_percpu(bt->sequence);
 	free_percpu(bt->msg_data);
 	kfree(bt);
@@ -336,7 +289,18 @@ static int blk_subbuf_start_callback(str
 
 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;
 }
 
@@ -393,7 +357,15 @@ int do_blk_trace_setup(struct request_qu
 		goto err;
 
 	ret = -ENOENT;
-	dir = blk_create_tree(buts->name);
+
+	if (!blk_tree_root) {
+		blk_tree_root = debugfs_create_dir("block", NULL);
+		if (!blk_tree_root)
+			return -ENOMEM;
+	}
+
+	dir = debugfs_create_dir(buts->name, blk_tree_root);
+
 	if (!dir)
 		goto err;
 
@@ -436,8 +408,6 @@ int do_blk_trace_setup(struct request_qu
 
 	return 0;
 err:
-	if (dir)
-		blk_remove_tree(dir);
 	if (bt) {
 		if (bt->msg_file)
 			debugfs_remove(bt->msg_file);