On Thu, Apr 16, 2020 at 12:29 AM Ming Lei <ming.lei@xxxxxxxxxx> wrote: > > On Thu, Apr 16, 2020 at 06:20:54AM +0000, Luis Chamberlain wrote: > > On Thu, Apr 16, 2020 at 01:47:50PM +0800, Ming Lei wrote: > > > On Thu, Apr 16, 2020 at 05:25:24AM +0000, Luis Chamberlain wrote: > > > > On Thu, Apr 16, 2020 at 10:10:36AM +0800, Ming Lei wrote: > > > > > In theory, multiple partitions can be traced concurrently, but looks > > > > > it never works, so it won't cause trouble for multiple partition trace. > > > > > > > > > > One userspace visible change is that blktrace debugfs dir name is switched > > > > > to disk name from partition name in case of partition trace, will it > > > > > break some utilities? > > > > > > > > How is this possible, its not clear to me, we go from: > > > > > > > > - q->debugfs_dir = debugfs_create_dir(kobject_name(q->kobj.parent), > > > > - blk_debugfs_root); > > > > > > > > To this: > > > > > > > > + q->debugfs_dir = debugfs_create_dir(kobject_name(q->kobj.parent), > > > > + blk_debugfs_root); > > > > > > > > > > > > Maybe I am overlooking something. > > > > > > Your patch removes the blktrace debugfs dir: > > > > > > do_blk_trace_setup() > > > > > > - dir = debugfs_lookup(buts->name, blk_debugfs_root); > > > - if (!dir) > > > - bt->dir = dir = debugfs_create_dir(buts->name, blk_debugfs_root); > > > - > > > > > > Then create blktrace attributes under the dir of q->debugfs_dir. > > > > > > However, buts->name could be one partition device name, but > > > > I can see how buts->name is set to bdevname() which expands to > > disk_name(bdev->bd_disk, bdev->bd_part->partno, buf). > > > > > q->debugfs_dir has to be disk name. > > > > I can't see this, can you point me to where it is clear the > > request_queue kobject's parent is sure to be the disk name? > > blk_register_queue(): > ... > ret = kobject_add(&q->kobj, kobject_get(&dev->kobj), "%s", "queue"); > ... Alright, I have a fix for this now, and I do have also a further explanation as to *why* the debugfs_lookup() doesn't help us here. I'll follow up with more patches. Luis
