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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 AD4A3C433F8 for ; Fri, 24 Jul 2020 16:46:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8A8A4206C1 for ; Fri, 24 Jul 2020 16:46:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595609183; bh=ronJJOZmDzLOufnZltpx4KGJDoNF7F4ILWGJHIg9sQk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=xx3tdaw14UTdkEqgE95JYDcEOPaJQ/ykZjVPIWvwuGNOAZjLBUf1z6sdZlyAvBfzp Zsq/ff/1uIL2sDgAOeAu7luztHHOjKza0YZ++syRkjAkje0xcTsnFA4czex/85oG9P uHWTPifxSGj/xtdvmKESPEFhJwo+eHcXonxdTpg8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726989AbgGXQqV (ORCPT ); Fri, 24 Jul 2020 12:46:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:58078 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726987AbgGXQqT (ORCPT ); Fri, 24 Jul 2020 12:46:19 -0400 Received: from sol.localdomain (c-107-3-166-239.hsd1.ca.comcast.net [107.3.166.239]) (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 94EBB206F0; Fri, 24 Jul 2020 16:46:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595609178; bh=ronJJOZmDzLOufnZltpx4KGJDoNF7F4ILWGJHIg9sQk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SzwpohwRf7jIyzTvokD9BSXkKYQWQ7SxhS9EMWW0EOIlQNKTkFWhUcj/g19PoZETD M6TozYZaIDRbeW/LB7hVnaqpti/XueLY/iFNzJ4OwqOJdQJQx5nMyiTDujtf80klZS NleNkGmecr8ac/3eThBusaaGEt7DTegp7JEdbLVE= Date: Fri, 24 Jul 2020 09:46:17 -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, Jaegeuk Kim Subject: Re: [PATCH v5 1/7] fscrypt: Add functions for direct I/O support Message-ID: <20200724164617.GA819@sol.localdomain> References: <20200724121143.1589121-1-satyat@google.com> <20200724121143.1589121-2-satyat@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200724121143.1589121-2-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 24, 2020 at 12:11:37PM +0000, Satya Tangirala wrote: > From: Eric Biggers > > Introduce fscrypt_dio_supported() to check whether a direct I/O request > is unsupported due to encryption constraints. > > Also introduce fscrypt_limit_io_blocks() to limit how many blocks can be > added to a bio being prepared for direct I/O. This is needed for > filesystems that use the iomap direct I/O implementation to avoid DUN > wraparound in the middle of a bio (which is possible with the > IV_INO_LBLK_32 IV generation method). Elsewhere fscrypt_mergeable_bio() > is used for this, but iomap operates on logical ranges directly, so > filesystems using iomap won't have a chance to call fscrypt_mergeable_bio() > on every block added to a bio. So we need this function which limits a > logical range in one go. > > Signed-off-by: Eric Biggers > Co-developed-by: Satya Tangirala > Signed-off-by: Satya Tangirala > Reviewed-by: Jaegeuk Kim Note, generally you should drop Reviewed-by tags if you make nontrivial changes. > +/** > + * fscrypt_limit_io_blocks() - limit I/O blocks to avoid discontiguous DUNs > + * @inode: the file on which I/O is being done > + * @pos: the file position (in bytes) at which the I/O is being done > + * @nr_blocks: the number of blocks we want to submit starting at @pos > + * > + * Determine the limit to the number of blocks that can be submitted in the bio > + * targeting @pos without causing a data unit number (DUN) discontinuity. > + * > + * This is normally just @nr_blocks, as normally the DUNs just increment along > + * with the logical blocks. (Or the file is not encrypted.) > + * > + * In rare cases, fscrypt can be using an IV generation method that allows the > + * DUN to wrap around within logically continuous blocks, and that wraparound > + * will occur. If this happens, a value less than @nr_blocks will be returned > + * so that the wraparound doesn't occur in the middle of the bio. > + * > + * Return: the actual number of blocks that can be submitted > + */ > +int fscrypt_limit_io_blocks(const struct inode *inode, loff_t pos, > + unsigned int nr_blocks) ext4 actually passes a block number for the second argument, not a position. Also, we should make this ready for 64-bit block numbers. When it's trivial to do, we keep fs/crypto/ ready for 64-bit block numbers, even though it's not needed yet. E.g. see fscrypt_crypt_block() and fscrypt_generate_iv(). It's true that currently this function is a no-op except for IV_INO_LBLK_32, but that's more of an implementation detail. So the prototype I recommend is: u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, u64 nr_blocks); > +{ > + const struct fscrypt_info *ci = inode->i_crypt_info; > + u32 dun; > + > + if (!fscrypt_inode_uses_inline_crypto(inode)) > + return nr_blocks; > + > + if (nr_blocks <= 1) > + return nr_blocks; > + > + if (!(fscrypt_policy_flags(&ci->ci_policy) & > + FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) > + return nr_blocks; > + > + /* With IV_INO_LBLK_32, the DUN can wrap around from U32_MAX to 0. */ > + > + dun = ci->ci_hashed_ino + (pos >> inode->i_blkbits); > + > + return min_t(u64, nr_blocks, (u64)U32_MAX + 1 - dun); > +} > diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h > index bb257411365f..241266cba21f 100644 > --- a/include/linux/fscrypt.h > +++ b/include/linux/fscrypt.h > @@ -559,6 +559,11 @@ bool fscrypt_mergeable_bio(struct bio *bio, const struct inode *inode, > bool fscrypt_mergeable_bio_bh(struct bio *bio, > const struct buffer_head *next_bh); > > +bool fscrypt_dio_supported(struct kiocb *iocb, struct iov_iter *iter); > + > +int fscrypt_limit_io_blocks(const struct inode *inode, loff_t pos, > + unsigned int nr_blocks); > + > #else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ > > static inline bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode) > @@ -587,6 +592,20 @@ static inline bool fscrypt_mergeable_bio_bh(struct bio *bio, > { > return true; > } > + > +static inline bool fscrypt_dio_supported(struct kiocb *iocb, > + struct iov_iter *iter) > +{ > + const struct inode *inode = file_inode(iocb->ki_filp); > + > + return !fscrypt_needs_contents_encryption(inode); > +} > + > +static inline int fscrypt_limit_io_blocks(const struct inode *inode, loff_t pos, > + unsigned int nr_blocks) > +{ > + return nr_blocks; > +} > #endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */ > > /** > -- > 2.28.0.rc0.142.g3c755180ce-goog >