Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933793AbbEOSah (ORCPT ); Fri, 15 May 2015 14:30:37 -0400 Received: from mail-ig0-f173.google.com ([209.85.213.173]:38471 "EHLO mail-ig0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932074AbbEOSaf (ORCPT ); Fri, 15 May 2015 14:30:35 -0400 MIME-Version: 1.0 In-Reply-To: <20150515025102.GI7232@ZenIV.linux.org.uk> References: <20150513222533.GA24192@ZenIV.linux.org.uk> <20150514033040.GF7232@ZenIV.linux.org.uk> <20150514220932.GC31808@samba2> <20150514233632.GG7232@ZenIV.linux.org.uk> <20150515012645.GH7232@ZenIV.linux.org.uk> <20150515025102.GI7232@ZenIV.linux.org.uk> Date: Fri, 15 May 2015 11:30:34 -0700 X-Google-Sender-Auth: Wq0_jgQXJS0CdO2a_xbELSmEugU Message-ID: Subject: Re: [RFC][PATCHSET v3] non-recursive pathname resolution & RCU symlinks From: Linus Torvalds To: Al Viro Cc: Jeremy Allison , Linux Kernel Mailing List , linux-fsdevel , Christoph Hellwig , Neil Brown Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1944 Lines: 39 On Thu, May 14, 2015 at 7:51 PM, Al Viro wrote: > > What's the benefit compared to c-i mount? Not hitting filesystem's > ->d_hash() and ->d_compare()? So the reason I'd be interested in per-access flags rather than mount flags are: - only special apps should use this anyway. IOW, samba and perhaps things like wine, and that's absolutely it. The argument that it might confuse "tar" is bogus, exactly because not only would tar never do this in the first place, tar absolutely *mustn't* do crap like this anyway. case-insensitive filesystems are insane, the *only* possible valid reason for them is for "emulate insane systems". - mount flags are bad. They'd be useless for something like wine (where you want to make part of the users home directory be the filesystem), and they are bad for things like samba too. Having to make a whole filesystem case-insensitive is crazy, because case-insensitivity is crazy. You want to make one application able to use case-insensitivity, not make all accesses so. - we do have cases where more per-access flags might be a really good idea. The whole "don't follow any/absolute symlinks" and "don't follow dotdot" are real concerns in various other places that now waste time trying to do it manually (and generally do it badly at that - see all the historical apache issues with dotdot to escape the publicly visible areas). I think it's a mistake in general to think that these kinds of things should be per-mount. That said, if the main/only reason samba would use this is for the case it would be bad at handling anyway (negative lookups in big directories), it's definitely not worth it. Linus -- 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/