From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (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 3F23C30B531 for ; Fri, 12 Sep 2025 13:09:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.95.11.211 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757682601; cv=none; b=ffK3+BDS1zj9UQsa2qn2+V7pGOUB98ZWnQi1ymGIyRZh01nsei7IbI8+WLMDYKNfcxLVH8xS3uCZFL7xYJFEhwgApNbfSuZiJyfcjqxcgHEGvbgBtaDZ+uEQSwrhMOyYj5ocqj0ulCRyiuZbqDeH90VNlhrmapS9QS6kyEvsGRU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757682601; c=relaxed/simple; bh=A65bF41Ieqrq9K+IwzU4tiorMOIGX0Ztr+kfK9r/PUQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Xkq115Efmnyy+abhBvuRbDUtQFbT5ODGmcUrqj6IdCQJWDM5UFxemuPKeAFO74jP3WHafqrNg3u33UKRW5t0ZrH+CZ1bPbX+gfNpbOB9LImWRZ29YBtNfGsqKLUcAzhZGU/wXsAuyCFkUyxtiUKA4LborAm6p78zMRc4hj2zEZs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de; spf=pass smtp.mailfrom=lst.de; arc=none smtp.client-ip=213.95.11.211 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lst.de Received: by verein.lst.de (Postfix, from userid 2407) id 89A8968BEB; Fri, 12 Sep 2025 15:09:53 +0200 (CEST) Date: Fri, 12 Sep 2025 15:09:53 +0200 From: Christoph Hellwig To: Andrey Albershteyn Cc: Christoph Hellwig , "Darrick J. Wong" , fsverity@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, david@fromorbit.com, ebiggers@kernel.org, Andrey Albershteyn Subject: Re: [PATCH RFC 02/29] iomap: introduce iomap_read/write_region interface Message-ID: <20250912130953.GA6754@lst.de> References: <20250728-fsverity-v1-0-9e5443af0e34@kernel.org> <20250728-fsverity-v1-2-9e5443af0e34@kernel.org> <20250729222252.GJ2672049@frogsfrogsfrogs> <20250811114337.GA8850@lst.de> <20250912071859.GB13505@lst.de> Precedence: bulk X-Mailing-List: fsverity@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: User-Agent: Mutt/1.5.17 (2007-11-01) On Fri, Sep 12, 2025 at 01:56:45PM +0200, Andrey Albershteyn wrote: > > > In addition to being bound by the isize the fiemap_read() copies > > > data to the iov_iter, which is not really needed for fsverity. > > > > Aka, you want an O_DIRECT read into a ITER_BVEC buffer for the data? > > > > hmm, but we want fsverity merkle tree to be in page cache to use the > "verified page" flag. Oh, right. There's this thing called caching :) > As far as I understand iter_bvec will need a > page attached anyway, so this is the same. Or am I missing > something? > > And with direct io there's no readahead then, and we don't get any > benefit going through vfs instead of directly calling to iomap. Yeah, strike my idea. So yes, you probably do want a lower level interface that just reads the pages and gives you access to them. > > -- > - Andrey ---end quoted text---