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blktrace: Make sure BLKTRACETEARDOWN does the full cleanup.

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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>
This commit is contained in:
Aneesh Kumar K.V 2007-11-21 12:25:41 +01:00 committed by Jens Axboe
parent 8c27eba549
commit 35fc51e7a5
1 changed files with 7 additions and 2 deletions
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9
block/blktrace.c
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@ -202,6 +202,7 @@ static void blk_remove_tree(struct dentry *dir)
static struct dentry *blk_create_tree(const char *blk_name)
{
struct dentry *dir = NULL;
int created = 0;
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);
if (!blk_tree_root)
goto err;
created = 1;
}
dir = debugfs_create_dir(blk_name, blk_tree_root);
if (dir)
root_users++;
else
blk_remove_root();
else {
/* Delete root only if we created it */
if (created)
blk_remove_root();
}
err:
mutex_unlock(&blk_tree_mutex);