From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman) Subject: Re: [PATCH 06/14] sysfs: Rewrite sysfs_get_dentry Date: Wed, 01 Aug 2007 11:07:39 -0600 Message-ID: References: <46AF15F6.6010202@suse.de> <46AF1E57.3030209@suse.de> <20070731141613.GC13674@htj.dyndns.org> <46B05A1D.5000703@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: In-Reply-To: <46B05A1D.5000703-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> (Tejun Heo's message of "Wed, 01 Aug 2007 19:02:05 +0900") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Tejun Heo Cc: Greg KH , Greg KH , cornelia.huck-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org, stern-nwvwT67g6+6dFdvTe/nMLpVzexx5G7lz@public.gmane.org, satyam-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, Linux Containers , Dave Hansen List-Id: containers.vger.kernel.org Tejun Heo writes: > Hello, Eric. > > Eric W. Biederman wrote: >> I will look a little more and see. But right now it looks like the >> real problem with locking is that we use sysfs_mutex to lock the >> sysfs_dirent s_children list. >> >> Instead it really looks like we should use i_mutex from the appropriate >> inode. Or is there a real performance problem with forcing the directory >> inodes in core when we modify the directories? > > I don't think there is any performance problem. Problems with using > i_mutex were... > > * It was messy. I don't remember all the details now but IIRC symlink > walk code was pretty complex. > > * And more importantly, inodes are reclaimable and might or might not be > there. Yes. But we can always force inodes into the cache when we need them. When I complete it I will have to show you a patch using the inode lock for locking directory modifications. From what I can tell so far it allows me to fix the weird lock order problems and generally simplify the locking. Eric