From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.133]:48054 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933282AbeEWPWm (ORCPT ); Wed, 23 May 2018 11:22:42 -0400 Date: Wed, 23 May 2018 08:22:39 -0700 From: Christoph Hellwig To: Kent Overstreet Cc: Christoph Hellwig , Matthew Wilcox , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton , Dave Chinner , darrick.wong@oracle.com, tytso@mit.edu, linux-btrfs@vger.kernel.org, clm@fb.com, jbacik@fb.com, viro@zeniv.linux.org.uk, peterz@infradead.org Subject: Re: [PATCH 01/10] mm: pagecache add lock Message-ID: <20180523152239.GA2425@infradead.org> References: <20180518074918.13816-1-kent.overstreet@gmail.com> <20180518074918.13816-3-kent.overstreet@gmail.com> <20180518131305.GA6361@bombadil.infradead.org> <20180518155330.GA16931@infradead.org> <20180520224524.GC11495@kmo-pixel> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180520224524.GC11495@kmo-pixel> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Sun, May 20, 2018 at 06:45:24PM -0400, Kent Overstreet wrote: > > > > Honestly I think this probably should be in the core. But IFF we move > > it to the core the existing users of per-fs locks need to be moved > > over first. E.g. XFS as the very first one, and at least ext4 and f2fs > > that copied the approach, and probably more if you audit deep enough. > > I'm not going to go and redo locking in XFS and ext4 as a prerequisite to > merging bcachefs. Sorry, but that's a bit crazy. It isn't crazy at all. In general we expect people to do their fair share of core work to get their pet feature in. How much is acceptable is a difficult question and not black and white. But if you want to grow a critical core structure you better take a stab at converting existing users. Without that the tradeoff of growing that core structure is simply not given. Or to put it in words for this exact feature: unless your new field is also used by mainstream file systems it is not going to be added.