Commit 35fc51e7 authored Nov 21, 2007 by Aneesh Kumar K.V Committed by Jens Axboe Nov 27, 2007

blktrace: Make sure BLKTRACETEARDOWN does the full cleanup.



if blktrace program segfault it will not be able
to call BLKTRACETEARDOWN. Now if we run the blktrace
again that would result in a failure to create the
block/<device> debugfs directory.This will result
in blk_remove_root() to be called which will set
blk_tree_root to NULL. But the  debugfs block dir
still exist because it contain subdirectory.

Now if we try to fix it using BLKTRACETEARDOWN
it won't work because blk_tree_root is NULL.

Fix the same.

Tested as below

root@qemu-image:/home/kvaneesh/blktrace# ./blktrace  -d /dev/hdc
Segmentation fault
root@qemu-image:/home/kvaneesh/blktrace# ./blktrace  -d /dev/hdc
BLKTRACESETUP: No such file or directory
Failed to start trace on /dev/hdc
root@qemu-image:/home/kvaneesh/blktrace# ./blktrace  -k /dev/hdc
root@qemu-image:/home/kvaneesh/blktrace# ./blktrace  -d /dev/hdc

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

parent 8c27eba5

block/blktrace.c

+7 −2

Original line number	Original line	Diff line number	Diff line
	@@ -202,6 +202,7 @@ static void blk_remove_tree(struct dentry *dir)
	static struct dentry blk_create_tree(const char blk_name)		static struct dentry blk_create_tree(const char blk_name)
	{		{
	struct dentry *dir = NULL;		struct dentry *dir = NULL;
			int created = 0;

	mutex_lock(&blk_tree_mutex);		mutex_lock(&blk_tree_mutex);

	@@ -209,13 +210,17 @@ static struct dentry blk_create_tree(const char blk_name)
	blk_tree_root = debugfs_create_dir("block", NULL);		blk_tree_root = debugfs_create_dir("block", NULL);
	if (!blk_tree_root)		if (!blk_tree_root)
	goto err;		goto err;
			created = 1;
	}		}

	dir = debugfs_create_dir(blk_name, blk_tree_root);		dir = debugfs_create_dir(blk_name, blk_tree_root);
	if (dir)		if (dir)
	root_users++;		root_users++;
	else		else {
			/* Delete root only if we created it */
			if (created)
	blk_remove_root();		blk_remove_root();
			}

	err:		err:
	mutex_unlock(&blk_tree_mutex);		mutex_unlock(&blk_tree_mutex);

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