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 X-Spam-Level: X-Spam-Status: No, score=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1A9EDC433E3 for ; Mon, 20 Jul 2020 19:29:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F194622BEF for ; Mon, 20 Jul 2020 19:29:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595273390; bh=p9MSRNwJssID8LsizQqfdqvIlunqUMeWXc/JgkGaXi0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=zmLt3t6y4Cm0Ua5k7ZPJbnKVQ8ZFMxRKSOCUUzCEFkgV+W+TMn1EoRnglPYGmNYiR b3HkUaRHc0d2VWVNtPd6US9G0eEvNrFv4CvAsD0UPkACCZi9fEbyvYzzzmsy39gF6D leX3FF0HbuMwOrWR8SB6pMOKqOXs7VflRejVwrLc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730108AbgGTT3s (ORCPT ); Mon, 20 Jul 2020 15:29:48 -0400 Received: from mail.kernel.org ([198.145.29.99]:44212 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726491AbgGTT3s (ORCPT ); Mon, 20 Jul 2020 15:29:48 -0400 Received: from gmail.com (unknown [104.132.1.76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3A1E620773; Mon, 20 Jul 2020 19:29:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595273387; bh=p9MSRNwJssID8LsizQqfdqvIlunqUMeWXc/JgkGaXi0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=GquwQiP/sRX76vVq9CjrWtrz91gsYU5skbVXwteYGpXuvF418/XjmOcLHqQld9G4K 3lrNMhrkXTB+kT0/xVAH8alRXHtdekNe4EKq+z+QZWLPKSTLoxRZA4ah54G8TlsWnh O+8/ei1YQ2RJZjTF7+98Xty5tQ+lTjHyqb+CbM1Y= Date: Mon, 20 Jul 2020 12:29:45 -0700 From: Eric Biggers To: Satya Tangirala Cc: linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org Subject: Re: [PATCH v3 3/7] iomap: support direct I/O with fscrypt using blk-crypto Message-ID: <20200720192945.GG1292162@gmail.com> References: <20200717014540.71515-1-satyat@google.com> <20200717014540.71515-4-satyat@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200717014540.71515-4-satyat@google.com> Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org On Fri, Jul 17, 2020 at 01:45:36AM +0000, Satya Tangirala wrote: > From: Eric Biggers > > Wire up iomap direct I/O with the fscrypt additions for direct I/O, > and set bio crypt contexts on bios when appropriate. > > Make iomap_dio_bio_actor() call fscrypt_limit_io_pages() to ensure that > DUNs remain contiguous within a bio, since it works directly with logical > ranges and can't call fscrypt_mergeable_bio() on each page. This commit message is still confusing. How about the following: "Wire up iomap direct I/O with the fscrypt additions for direct I/O. This allows ext4 to support direct I/O on encrypted files when inline encryption is enabled. This change consists of two parts: - Set a bio_crypt_ctx on bios for encrypted files, so that the file contents get encrypted (or decrypted). - Ensure that encryption data unit numbers (DUNs) are contiguous within each bio. Use the new function fscrypt_limit_io_pages() for this, since the iomap code works directly with logical ranges and thus doesn't have a chance to call fscrypt_mergeable_bio() on each page. Note that fscrypt_limit_io_pages() is normally a no-op, as normally the DUNs simply increment along with the logical blocks. But it's needed to handle an edge case in one of the fscrypt IV generation methods." > @@ -183,11 +184,14 @@ static void > iomap_dio_zero(struct iomap_dio *dio, struct iomap *iomap, loff_t pos, > unsigned len) > { > + struct inode *inode = file_inode(dio->iocb->ki_filp); > struct page *page = ZERO_PAGE(0); > int flags = REQ_SYNC | REQ_IDLE; > struct bio *bio; > > bio = bio_alloc(GFP_KERNEL, 1); > + fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits, > + GFP_KERNEL); > bio_set_dev(bio, iomap->bdev); > bio->bi_iter.bi_sector = iomap_sector(iomap, pos); > bio->bi_private = dio; iomap_dio_zero() is only used on partial filesystem blocks. But, we only allow direct I/O on encrypted files when the I/O is filesystem-block-aligned. So this part appears to be unnecessary. How about replacing it with: /* encrypted direct I/O is guaranteed to be fs-block aligned */ WARN_ON_ONCE(fscrypt_needs_contents_encryption(inode)); > @@ -253,6 +257,7 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length, > ret = nr_pages; > goto out; > } > + nr_pages = fscrypt_limit_io_pages(inode, pos, nr_pages); > > if (need_zeroout) { > /* zero out from the start of the block to the write offset */ > @@ -270,6 +275,8 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length, > } > > bio = bio_alloc(GFP_KERNEL, nr_pages); > + fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits, > + GFP_KERNEL); > bio_set_dev(bio, iomap->bdev); > bio->bi_iter.bi_sector = iomap_sector(iomap, pos); > bio->bi_write_hint = dio->iocb->ki_hint; > @@ -307,6 +314,7 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length, > copied += n; > > nr_pages = iov_iter_npages(dio->submit.iter, BIO_MAX_PAGES); > + nr_pages = fscrypt_limit_io_pages(inode, pos, nr_pages); > iomap_dio_submit_bio(dio, iomap, bio, pos); > pos += n; > } while (nr_pages); I think the part at the end is wrong. We want to limit the *next* bio, not the current one. So 'pos' needs to be updated first. I think it should be: iomap_dio_submit_bio(dio, iomap, bio, pos); pos += n; nr_pages = iov_iter_npages(dio->submit.iter, BIO_MAX_PAGES); nr_pages = fscrypt_limit_io_pages(inode, pos, nr_pages);