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[213.95.11.211]) by mx.google.com with ESMTPS id v18si16517202wri.292.2019.04.25.08.03.55 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 25 Apr 2019 08:03:55 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of hch@lst.de designates 213.95.11.211 as permitted sender) client-ip=213.95.11.211; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of hch@lst.de designates 213.95.11.211 as permitted sender) smtp.mailfrom=hch@lst.de Received: by newverein.lst.de (Postfix, from userid 2407) id 7866168B20; Thu, 25 Apr 2019 17:03:40 +0200 (CEST) Date: Thu, 25 Apr 2019 17:03:40 +0200 From: Christoph Hellwig To: Jan Kara Cc: Andreas Gruenbacher , cluster-devel@redhat.com, Christoph Hellwig , Bob Peterson , Dave Chinner , Ross Lagerwall , Mark Syms , Edwin =?iso-8859-1?B?VPZy9ms=?= , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 1/2] iomap: Add a page_prepare callback Message-ID: <20190425150340.GA17504@lst.de> References: <20190424171804.4305-1-agruenba@redhat.com> <20190425083252.GB21215@quack2.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190425083252.GB21215@quack2.suse.cz> User-Agent: Mutt/1.5.17 (2007-11-01) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Apr 25, 2019 at 10:32:52AM +0200, Jan Kara wrote: > Also just looking at the code I was wondering about the following. E.g. in > iomap_write_end() we have code like: > > if (iomap->type == IOMAP_INLINE) { > foo > } else if (iomap->flags & IOMAP_F_BUFFER_HEAD) { > bar > } else { > baz > } > > if (iomap->page_done) > iomap->page_done(...); > > And now something very similar is in iomap_write_begin(). So won't it be > more natural to just mandate ->page_prepare() and ->page_done() callbacks > and each filesystem would set it to a helper function it needs? Probably we > could get rid of IOMAP_F_BUFFER_HEAD flag that way... I don't want pointless indirect calls for the default, non-buffer head case. Also inline really is a special case independent of what the caller could pass in as flags or callbacks. We could try to hide the buffer_head stuff in there, but then again I'd rather kill that off sooner than later.