From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2561D70 for ; Tue, 27 Jul 2021 14:32:57 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id A8053603E7; Tue, 27 Jul 2021 14:32:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1627396376; bh=P+J3nIURP3B0hGzMIl54oyj1L6/yl7CDmXAm5X+Upx8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=mrlGqwmpjfPpgIzgTRGvv8csrCB9SF7IAeAXSl4PoYy4iHOL8O7IQYDa4eZu4E+7C 1OaUNt7sGa++izEvGezUm4A51hFgnFq/otisMzdmjNXAX54GLwKWj5K/orOK2B6S1v XglpIa8SNerVvNFX5K5SD/TrRB+AvsU3281uQ1BiTC6o4EXW3QZJCVVCJ33pM+NlJm L3VPYLxHOsKcEElZIdokwaqGoub+L6oWy+apXEDlQpMVQj7k7qbq0hXCQmhVKpiKtO v+lwBnYgi/S5VV0CcbVlTi3CTNmvbAJrktYncwHyG+GYNgGiXBwuqtUsZX8lH/OQdw uHMmFHkU98lMA== Date: Tue, 27 Jul 2021 07:32:56 -0700 From: "Darrick J. Wong" To: Christoph Hellwig Cc: Dan Williams , Matthew Wilcox , Andreas Gruenbacher , Shiyang Ruan , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-btrfs@vger.kernel.org, nvdimm@lists.linux.dev, cluster-devel@redhat.com Subject: Re: [PATCH 16/27] iomap: switch iomap_bmap to use iomap_iter Message-ID: <20210727143256.GC559142@magnolia> References: <20210719103520.495450-1-hch@lst.de> <20210719103520.495450-17-hch@lst.de> <20210719170545.GF22402@magnolia> <20210726081942.GD14853@lst.de> <20210726163922.GA559142@magnolia> <20210727063138.GA10143@lst.de> Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210727063138.GA10143@lst.de> On Tue, Jul 27, 2021 at 08:31:38AM +0200, Christoph Hellwig wrote: > On Mon, Jul 26, 2021 at 09:39:22AM -0700, Darrick J. Wong wrote: > > The documentation needs to be much more explicit about the fact that you > > cannot "break;" your way out of an iomap_iter loop. I think the comment > > should be rewritten along these lines: > > > > "Iterate over filesystem-provided space mappings for the provided file > > range. This function handles cleanup of resources acquired for > > iteration when the filesystem indicates there are no more space > > mappings, which means that this function must be called in a loop that > > continues as long it returns a positive value. If 0 or a negative value > > is returned, the caller must not return to the loop body. Within a loop > > body, there are two ways to break out of the loop body: leave > > @iter.processed unchanged, or set it to the usual negative errno." > > > > Hm. > > Yes, I'll update the documentation. Ok, thanks! > > Clunky, for sure, but at least we still get to use break as the language > > designers intended. > > I can't see any advantage there over just proper documentation. If you > are totally attached to a working break we might have to come up with > a nasty for_each macro that ensures we have a final iomap_apply, but I > doubt it is worth the effort. I was pushing the explicit _break() function as a means to avoid an even fuglier loop macro. --D From mboxrd@z Thu Jan 1 00:00:00 1970 From: Darrick J. Wong Date: Tue, 27 Jul 2021 07:32:56 -0700 Subject: [Cluster-devel] [PATCH 16/27] iomap: switch iomap_bmap to use iomap_iter In-Reply-To: <20210727063138.GA10143@lst.de> References: <20210719103520.495450-1-hch@lst.de> <20210719103520.495450-17-hch@lst.de> <20210719170545.GF22402@magnolia> <20210726081942.GD14853@lst.de> <20210726163922.GA559142@magnolia> <20210727063138.GA10143@lst.de> Message-ID: <20210727143256.GC559142@magnolia> List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Tue, Jul 27, 2021 at 08:31:38AM +0200, Christoph Hellwig wrote: > On Mon, Jul 26, 2021 at 09:39:22AM -0700, Darrick J. Wong wrote: > > The documentation needs to be much more explicit about the fact that you > > cannot "break;" your way out of an iomap_iter loop. I think the comment > > should be rewritten along these lines: > > > > "Iterate over filesystem-provided space mappings for the provided file > > range. This function handles cleanup of resources acquired for > > iteration when the filesystem indicates there are no more space > > mappings, which means that this function must be called in a loop that > > continues as long it returns a positive value. If 0 or a negative value > > is returned, the caller must not return to the loop body. Within a loop > > body, there are two ways to break out of the loop body: leave > > @iter.processed unchanged, or set it to the usual negative errno." > > > > Hm. > > Yes, I'll update the documentation. Ok, thanks! > > Clunky, for sure, but at least we still get to use break as the language > > designers intended. > > I can't see any advantage there over just proper documentation. If you > are totally attached to a working break we might have to come up with > a nasty for_each macro that ensures we have a final iomap_apply, but I > doubt it is worth the effort. I was pushing the explicit _break() function as a means to avoid an even fuglier loop macro. --D