From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DA7A3C7619A for ; Wed, 5 Apr 2023 22:54:24 +0000 (UTC) Received: from [127.0.0.1] (helo=sfs-ml-1.v29.lw.sourceforge.com) by sfs-ml-1.v29.lw.sourceforge.com with esmtp (Exim 4.95) (envelope-from ) id 1pkC1I-0003Kx-5C; Wed, 05 Apr 2023 22:54:23 +0000 Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-1.v29.lw.sourceforge.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1pkC1E-0003Kq-3u for linux-f2fs-devel@lists.sourceforge.net; Wed, 05 Apr 2023 22:54:19 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; h=In-Reply-To:Content-Type:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=6JUsAGKEXzuNd3ZoMR2OtLIul6CggHLj09DSy7aat6U=; b=NJfQQ6bFQEif/AeEIWpqnfCfE2 FIB8bUDul9BeBw0vTdH+95JNlvrWNdjT0YpvZl3Q91OLBRwqBK5fZLtHIJiTVuuaHjJZiIMRVHfac NCfknsN6tQLtaeccLUpKPwpk6csiIxEP3INIGHPoYw0/OfXynhazaug6wdfHO1G31lZY=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x ; h=In-Reply-To:Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To :From:Date:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=6JUsAGKEXzuNd3ZoMR2OtLIul6CggHLj09DSy7aat6U=; b=L/esK5rbM5gdgRICn0jghXBKX6 UOBpZKA2agUyM9zGSKhTNdUa1E8gkiyLzTQIavfSY9a8YkKyZ+Mk/GAGSDgjB1fK9eZoNs5L0pBV0 tA9D/b4alQYGLjE7i14eHFEQbsHUCKU4MlEIo7s3PdoSFYE5eNUmHxD4RYddCkP8Qs60=; Received: from dfw.source.kernel.org ([139.178.84.217]) by sfi-mx-1.v28.lw.sourceforge.com with esmtps (TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.95) id 1pkC1B-00GM0Z-Au for linux-f2fs-devel@lists.sourceforge.net; Wed, 05 Apr 2023 22:54:19 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 588C86413E; Wed, 5 Apr 2023 22:54:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 722A6C433EF; Wed, 5 Apr 2023 22:54:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1680735247; bh=y5XoOju2yBDL4YDibMiieXpA89mTn+Rteq91AiPxCaU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LovyRg/EAV0o26rHWyr3wwdJKBIWeqs2RWTqBiuMA93Uopo6KQP/kuk5d1BnGrKHX eXiQmEFzna6WH31jznXOQEsuU8fCZaqbF53Fy9IDiBzVWVzNlq3Fcms5RC/AHMk3CM OAU4zbey8PXa+toYXE1InTyNADGV791ee94FuTsdJtQmtxfk26JoNlrEZbAnyuI7RM Tdnt072GBeEL29vP8V8lyr806zJWwdzwvcrm09fKje0OdHL52/Fkji9DdhPvGeeRQZ JSFgndGfwhFR5/2N8nLhm2oMnQAOUpmI5ryVtmOxxrkwIl3UfC3Gz24KpM4fDrDRV4 EANBOVoAcG1Tg== Date: Wed, 5 Apr 2023 22:54:06 +0000 From: Eric Biggers To: Dave Chinner Message-ID: References: <20230404145319.2057051-1-aalbersh@redhat.com> <20230404145319.2057051-22-aalbersh@redhat.com> <20230404163602.GC109974@frogsfrogsfrogs> <20230405160221.he76fb5b45dud6du@aalbersh.remote.csb> <20230405163847.GG303486@frogsfrogsfrogs> <20230405222646.GR3223426@dread.disaster.area> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20230405222646.GR3223426@dread.disaster.area> X-Headers-End: 1pkC1B-00GM0Z-Au Subject: Re: [f2fs-dev] [PATCH v2 21/23] xfs: handle merkle tree block size != fs blocksize != PAGE_SIZE X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: fsverity@lists.linux.dev, linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org, agruenba@redhat.com, "Darrick J. Wong" , Andrey Albershteyn , linux-f2fs-devel@lists.sourceforge.net, hch@infradead.org, cluster-devel@redhat.com, dchinner@redhat.com, rpeterso@redhat.com, xiang@kernel.org, jth@kernel.org, linux-erofs@lists.ozlabs.org, damien.lemoal@opensource.wdc.com, linux-btrfs@vger.kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net On Thu, Apr 06, 2023 at 08:26:46AM +1000, Dave Chinner wrote: > > We could certainly think about moving to a design where fs/verity/ asks the > > filesystem to just *read* a Merkle tree block, without adding it to a cache, and > > then fs/verity/ implements the caching itself. That would require some large > > changes to each filesystem, though, unless we were to double-cache the Merkle > > tree blocks which would be inefficient. > > No, that's unnecessary. > > All we need if for fsverity to require filesystems to pass it byte > addressable data buffers that are externally reference counted. The > filesystem can take a page reference before mapping the page and > passing the kaddr to fsverity, then unmap and drop the reference > when the merkle tree walk is done as per Andrey's new drop callout. > > fsverity doesn't need to care what the buffer is made from, how it > is cached, what it's life cycle is, etc. The caching mechanism and > reference counting is entirely controlled by the filesystem callout > implementations, and fsverity only needs to deal with memory buffers > that are guaranteed to live for the entire walk of the merkle > tree.... Sure. Just a couple notes: First, fs/verity/ does still need to be able to tell whether the buffer is newly instantiated or not. Second, fs/verity/ uses the ahash API to do the hashing. ahash is a scatterlist-based API. Virtual addresses can still be used (see sg_set_buf()), but the memory cannot be vmalloc'ed memory, since virt_to_page() needs to work. Does XFS use vmalloc'ed memory for these buffers? BTW, converting fs/verity/ from ahash to shash is an option; I've really never been a fan of the scatterlist-based crypto APIs! The disadvantage of doing this, though, would be that it would remove support for all the hardware crypto drivers. That *might* actually be okay, as that approach to crypto acceleration has mostly fallen out of favor, in favor of CPU-based acceleration. But I do worry about e.g. someone coming out of the woodwork and saying they need to use fsverity on a low-powered ARM board that has a crypto accelerator like CAAM, and they MUST use their crypto accelerator to get acceptable performance. - Eric _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel