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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 EDE42C432C0 for ; Tue, 3 Dec 2019 19:30:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B29C220803 for ; Tue, 3 Dec 2019 19:30:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575401432; bh=3gyEXfaqpedy6uRB/8VMCVxDlcKhW09vYVAVCCnolyc=; h=From:To:Cc:Subject:Date:List-ID:From; b=So6TQ782RDXyLBmwI0QNkNK3OOJxtiM8YlCLC9yeqrpjMTrnMOkJLzYjYmw2Ixt8y AImxkjYxgE3rg/M5H3ebpRQG6oJBoM8HIIN1YbBbvIlGWhe4W5WGuBKrGHPPfEvt5/ q9zfw37+1hse0rx3hIcoajNgLTlApr97P+RK0Y2M= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727081AbfLCTac (ORCPT ); Tue, 3 Dec 2019 14:30:32 -0500 Received: from mail.kernel.org ([198.145.29.99]:33398 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726079AbfLCTac (ORCPT ); Tue, 3 Dec 2019 14:30:32 -0500 Received: from sol.localdomain (c-24-5-143-220.hsd1.ca.comcast.net [24.5.143.220]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5BB2020640; Tue, 3 Dec 2019 19:30:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1575401430; bh=3gyEXfaqpedy6uRB/8VMCVxDlcKhW09vYVAVCCnolyc=; h=From:To:Cc:Subject:Date:From; b=FgKYpKIkk9MEV83ohzNgDB9G/T4o/iQ9m7o1UFMrbwOfpVwLcE5dD9OHGkoTo2LwO PnmEWqfvlFJ7EEGzDeoEmMV/1up/GnGaLng94nHb2TTD2h7CF+SsoBT/rBFnFdPT08 Bdspll56L0sEIIuHxA4aDIZrtITbN6Fv1Bv4tK0E= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, Victor Hsieh Subject: [PATCH] fs-verity: implement readahead for FS_IOC_ENABLE_VERITY Date: Tue, 3 Dec 2019 11:30:01 -0800 Message-Id: <20191203193001.66906-1-ebiggers@kernel.org> X-Mailer: git-send-email 2.24.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org From: Eric Biggers When it builds the first level of the Merkle tree, FS_IOC_ENABLE_VERITY sequentially reads each page of the file using read_mapping_page(). This works fine if the file's data is already in pagecache, which should normally be the case, since this ioctl is normally used immediately after writing out the file. But in any other case this implementation performs very poorly, since only one page is read at a time. Fix this by implementing readahead using the functions from mm/readahead.c. This improves performance in the uncached case by about 20x, as seen in the following benchmarks done on a 250MB file (on x86_64 with SHA-NI): FS_IOC_ENABLE_VERITY uncached (before) 3.299s FS_IOC_ENABLE_VERITY uncached (after) 0.160s FS_IOC_ENABLE_VERITY cached 0.147s sha256sum uncached 0.191s sha256sum cached 0.145s Note: we could instead switch to kernel_read(). But that would mean we'd no longer be hashing the data directly from the pagecache, which is a nice optimization of its own. And using kernel_read() would require allocating another temporary buffer, hashing the data and tree pages separately, and explicitly zero-padding the last page -- so it wouldn't really be any simpler than direct pagecache access, at least for now. Signed-off-by: Eric Biggers --- fs/verity/enable.c | 46 ++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 40 insertions(+), 6 deletions(-) diff --git a/fs/verity/enable.c b/fs/verity/enable.c index eabc6ac19906..f7eaffa60196 100644 --- a/fs/verity/enable.c +++ b/fs/verity/enable.c @@ -13,14 +13,44 @@ #include #include -static int build_merkle_tree_level(struct inode *inode, unsigned int level, +/* + * Read a file data page for Merkle tree construction. Do aggressive readahead, + * since we're sequentially reading the entire file. + */ +static struct page *read_file_data_page(struct inode *inode, + struct file_ra_state *ra, + struct file *filp, + pgoff_t index, + pgoff_t num_pages_in_file) +{ + struct page *page; + + page = find_get_page(inode->i_mapping, index); + if (!page || !PageUptodate(page)) { + if (page) + put_page(page); + page_cache_sync_readahead(inode->i_mapping, ra, filp, + index, num_pages_in_file - index); + page = read_mapping_page(inode->i_mapping, index, NULL); + if (IS_ERR(page)) + return page; + } + if (PageReadahead(page)) + page_cache_async_readahead(inode->i_mapping, ra, filp, page, + index, num_pages_in_file - index); + return page; +} + +static int build_merkle_tree_level(struct file *filp, unsigned int level, u64 num_blocks_to_hash, const struct merkle_tree_params *params, u8 *pending_hashes, struct ahash_request *req) { + struct inode *inode = file_inode(filp); const struct fsverity_operations *vops = inode->i_sb->s_vop; unsigned int pending_size = 0; + struct file_ra_state ra = { 0 }; u64 dst_block_num; u64 i; int err; @@ -36,6 +66,8 @@ static int build_merkle_tree_level(struct inode *inode, unsigned int level, dst_block_num = 0; /* unused */ } + file_ra_state_init(&ra, inode->i_mapping); + for (i = 0; i < num_blocks_to_hash; i++) { struct page *src_page; @@ -45,7 +77,8 @@ static int build_merkle_tree_level(struct inode *inode, unsigned int level, if (level == 0) { /* Leaf: hashing a data block */ - src_page = read_mapping_page(inode->i_mapping, i, NULL); + src_page = read_file_data_page(inode, &ra, filp, i, + num_blocks_to_hash); if (IS_ERR(src_page)) { err = PTR_ERR(src_page); fsverity_err(inode, @@ -103,17 +136,18 @@ static int build_merkle_tree_level(struct inode *inode, unsigned int level, } /* - * Build the Merkle tree for the given inode using the given parameters, and + * Build the Merkle tree for the given file using the given parameters, and * return the root hash in @root_hash. * * The tree is written to a filesystem-specific location as determined by the * ->write_merkle_tree_block() method. However, the blocks that comprise the * tree are the same for all filesystems. */ -static int build_merkle_tree(struct inode *inode, +static int build_merkle_tree(struct file *filp, const struct merkle_tree_params *params, u8 *root_hash) { + struct inode *inode = file_inode(filp); u8 *pending_hashes; struct ahash_request *req; u64 blocks; @@ -139,7 +173,7 @@ static int build_merkle_tree(struct inode *inode, blocks = (inode->i_size + params->block_size - 1) >> params->log_blocksize; for (level = 0; level <= params->num_levels; level++) { - err = build_merkle_tree_level(inode, level, blocks, params, + err = build_merkle_tree_level(filp, level, blocks, params, pending_hashes, req); if (err) goto out; @@ -227,7 +261,7 @@ static int enable_verity(struct file *filp, */ pr_debug("Building Merkle tree...\n"); BUILD_BUG_ON(sizeof(desc->root_hash) < FS_VERITY_MAX_DIGEST_SIZE); - err = build_merkle_tree(inode, ¶ms, desc->root_hash); + err = build_merkle_tree(filp, ¶ms, desc->root_hash); if (err) { fsverity_err(inode, "Error %d building Merkle tree", err); goto rollback; -- 2.24.0