On Tue, Jan 22, 2013 at 11:31:35PM -0500, Steven Rostedt wrote: > On Tue, 2013-01-22 at 20:08 -0800, Greg Kroah-Hartman wrote: > > > > Is doing something as silly as the following fine, or is there a better > > > way? > > > > Yes, why not create your own fs for ftrace? :) > > But but but... > > debugfs is soooo convenient! > > Do you think it would be worth doing that though? I only need the mkdir > and rmdir for this one instance. Nothing more. > > > > mutex_unlock(&inode->i_mutex); > > > > > > ret = new_instance_create(dentry->d_iname); > > > > > > mutex_lock(&inode->i_mutex); > > > > > > But how can you callback to your code to let it know that something was > > created in it? > > I pass the dentry->d_iname to create a directory. > > > > > Don't you need that for both mkdir and rmdir? > > It's a global list. It's very specific and doesn't need to be robust. It > all deals with modifying one global parameter. Not that hard. And I've > already implemented this. It works quite well :-) > > > > > But again, I'd really not want to do this in debugfs, how about your own > > filesystem? > > I will note that this never modifies the debugfs code. But it does > circumvent it. Ah, I like circumventing debugfs, it kind of fits right into its mission :) > That is, all this code lives in kernel/trace/trace.c. I don't modify > any of the debugfs code. I just replace the debugfs > dentry->d_inode->i_op with my own ops. Oh, ok, I thought you were talking about modifying the debugfs core. > I can create my own fs, but that just seems to be overkill. The only > difference is that I need mkdir and rmdir for this one instance. > > That said, perhaps it wouldn't be too hard to create a ftracefs. Where > should it go? fs/ftrace or perhaps kernel/trace/fs ? Sure, it only takes 300 lines to write a fs so it's not hard to do your own. > I notice that I only use: > > debugfs_create_file() > debugfs_remove(); > debugfs_create_dir(); > debugfs_remove_recursive(); > debugfs_initialized() > > so maybe it wouldn't be such a far fetch thing to implement. > > But then would I be able to still mount it in /debug/tracing ? As this > is where everything currently uses it? But then we need to teach admins > to add it there, or someplace else. /sys/kernel/ftrace? > > Tools like trace-cmd and perf already expect it to be in the debugfs > tracing directory, and will automate mounting it to /sys/kernel/debug/ > if not found. This may break userspace if I make another fs. Yes, you would need to require distros to mount it in the proper place, which is a pain, but not impossible. It's up to you, as I thought you needed to modify debugfs, I didn't like it, but if you can do it in your own code, I really don't care anymore :) greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
