From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Kent Subject: Re: [PATCH] autofs4 - use simple_empty() for empty directory check Date: Sat, 17 Nov 2012 10:29:01 +0800 Message-ID: <1353119341.2338.1.camel@perseus.themaw.net> References: <20121116041523.18624.46918.stgit@perseus.themaw.net> <1353083773.2332.40.camel@perseus.themaw.net> <20121116173415.GA16916@ZenIV.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Linus Torvalds , Kernel Mailing List , autofs mailing list , linux-fsdevel To: Al Viro Return-path: In-Reply-To: <20121116173415.GA16916@ZenIV.linux.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Fri, 2012-11-16 at 17:34 +0000, Al Viro wrote: > On Fri, Nov 16, 2012 at 08:43:28AM -0800, Linus Torvalds wrote: > > On Fri, Nov 16, 2012 at 8:36 AM, Ian Kent wrote: > > > > > > Sure, are you recommending I alter the fs/libfs.c functions to add a > > > function that doesn't have the outer lock, and have simple_empty() call > > > that, then use it in autofs? > > > > Yup. That's the standard pattern, although usually we *strive* to make > > the unlocked versions be static to the internal code, and then use > > them there for the various helpers. In your case that seems > > impossible, since you do depend on holding the d_lock in the caller > > after the tests. But at least we don't have to duplicate the code and > > have it in two unrelated places. > > > > Al? Comments? > > The thing is, I'm not convinced we really need ->d_lock held downstream. > E.g. __autofs4_add_expiring() ought to be OK with just sbi->lookup_lock. > Not sure about the situation in autofs4_d_automount() - the thing is messy > as hell ;-/ > > Ian, do we really need that __simple_empty() variant in either caller? What > is getting protected by ->d_lock after it and do we really need ->d_lock > continuously held for that? Yeah, I've thought about that a few times now but haven't gone so far as to change it. I'll have another look. Ian