Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761997Ab2FHQWl (ORCPT ); Fri, 8 Jun 2012 12:22:41 -0400 Received: from fieldses.org ([174.143.236.118]:45281 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755824Ab2FHQWj (ORCPT ); Fri, 8 Jun 2012 12:22:39 -0400 Date: Fri, 8 Jun 2012 12:22:34 -0400 To: Al Viro Cc: Dave Jones , Linus Torvalds , Linux Kernel , Miklos Szeredi , Jan Kara , Peter Zijlstra , linux-fsdevel@vger.kernel.org, "J. Bruce Fields" , "Eric W. Biederman" , Sage Weil Subject: Re: processes hung after sys_renameat, and 'missing' processes Message-ID: <20120608162234.GB17251@fieldses.org> References: <20120606194233.GA1537@redhat.com> <20120606230040.GA18089@redhat.com> <20120606235403.GC30000@ZenIV.linux.org.uk> <20120607002914.GB22223@redhat.com> <20120607011915.GA17566@redhat.com> <20120607012900.GE30000@ZenIV.linux.org.uk> <20120607193607.GI30000@ZenIV.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120607193607.GI30000@ZenIV.linux.org.uk> User-Agent: Mutt/1.5.20 (2009-06-14) From: "J. Bruce Fields" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1490 Lines: 37 On Thu, Jun 07, 2012 at 08:36:07PM +0100, Al Viro wrote: > * d_splice_alias() - broken. Called without any locking on the > old directory, nevermind ->s_vfs_rename_mutex. I was assuming that the callers were in lookup, held i_mutex on a parent, and that in the case of a directory, existence of an alias with a different parent could only result from a filesystem bug. > I really believe that this pair of commits needs to be reverted. The > earlier code used to guarantee that alias would be detached. In the case that prompted that first commit, the directory in question had an alias that was detached (which I'm taking to mean IS_ROOT(dentry) was true?), but not flagged DISCONNECTED. The particular case was only reproduceable on an older kernel, and I couldn't find a similar reproducer on recent upstream, but I also couldn't convince myself it was impossible. So, maybe the correct thing is to revert that change. Or maybe it should be picking an IS_ROOT dentry instead of a DISCONNECTED one? There's some previous discussion at http://marc.info/?i=<20110310105821.GE22723@ZenIV.linux.org.uk> (in particular a long post from Neil: http://marc.info/?i=<20110311150749.2fa2be66@notabene.brown> that I should review.) --b. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/