From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.133]:35206 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728051AbeLSHJR (ORCPT ); Wed, 19 Dec 2018 02:09:17 -0500 Date: Tue, 18 Dec 2018 23:09:15 -0800 From: Christoph Hellwig To: Eric Biggers Cc: Christoph Hellwig , linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, "Theodore Y . Ts'o" , Jaegeuk Kim , Victor Hsieh , Chandan Rajendra , Linus Torvalds Subject: Re: [PATCH v2 01/12] fs-verity: add a documentation file Message-ID: <20181219070915.GA2628@infradead.org> References: <20181101225230.88058-1-ebiggers@kernel.org> <20181101225230.88058-2-ebiggers@kernel.org> <20181212091406.GA31723@infradead.org> <20181212202609.GA193967@gmail.com> <20181213202249.GA3797@infradead.org> <20181214044802.GA681@sol.localdomain> <20181217164949.GA18626@infradead.org> <20181217183205.GA141684@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181217183205.GA141684@gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Mon, Dec 17, 2018 at 10:32:06AM -0800, Eric Biggers wrote: > I don't see how that helps. The Merkle tree can still be too large to fit in > memory. In the worst case, it might not even fit in the address space. And I > don't see how get_user_pages() helps either over just copy_from_user(); what are > you proposing to do with the pages after getting them, exactly? Write them out to a file system specific area on the media. Note that get_user_pages is indeed not going to work if you run out of address space, but that seems like an odd use case. Out of of memory is not an issue as we generally iterate over a small number of pages for each individual get_user_pages call.