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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E8FA9C25B0E for ; Mon, 15 Aug 2022 11:45:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230061AbiHOLpv (ORCPT ); Mon, 15 Aug 2022 07:45:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60144 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241432AbiHOLps (ORCPT ); Mon, 15 Aug 2022 07:45:48 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 08F75B4BB for ; Mon, 15 Aug 2022 04:45:48 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id B808D20866; Mon, 15 Aug 2022 11:45:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1660563946; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=eTUxYj1OZDkY14aB7vIzWLz6w9dpyMmDNCfmBP+tQss=; b=vYKQQAcOZvfBzzTVRPp2uMoKJ2+Oq7ldkICJXN1nBPStK/RnQ+wBkKzfSCizuTbNj+xH8O a2jgwsZ2XGjjGZVrYQMKO6db8zDlTmBQ4IgZCQM0XtUHGZxEWKLMwRi5VIZGK5EAwTr403 gPYHmnvtYWEicOiRynkrXXzk1dq/aC4= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 35DCE13A93; Mon, 15 Aug 2022 11:45:43 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id uGLIOucx+mLsGAAAMHmgww (envelope-from ); Mon, 15 Aug 2022 11:45:43 +0000 From: Qu Wenruo To: u-boot@lists.denx.de Cc: marek.behun@nic.cz, linux-btrfs@vger.kernel.org, jnhuang95@gmail.com, linux-erofs@lists.ozlabs.org, trini@konsulko.com, joaomarcos.costa@bootlin.com, thomas.petazzoni@bootlin.com, miquel.raynal@bootlin.com Subject: [PATCH v3 2/8] fs: btrfs: fix a bug which no data get read if the length is not 0 Date: Mon, 15 Aug 2022 19:45:13 +0800 Message-Id: X-Mailer: git-send-email 2.37.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org [BUG] When testing with unaligned read, if a specific length is passed in, btrfs driver will read out nothing: => load host 0 $kernel_addr_r 5k_file 0x1000 0 0 bytes read in 0 ms But if no length is passed in, it works fine, even if we pass a non-zero length: => load host 0 $kernel_addr_r 5k_file 0 0x1000 1024 bytes read in 0 ms [CAUSE] In btrfs_read() if we have a larger size than our file, we will try to truncate it using the file size. However the real file size is not initialized if @len is not zero, thus we always truncate our length to 0, and cause the problem. [FIX] Fix it by just always do the file size check. In fact btrfs_size() always follow soft link, thus it will return the real file size correctly. Signed-off-by: Qu Wenruo --- fs/btrfs/btrfs.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/fs/btrfs/btrfs.c b/fs/btrfs/btrfs.c index 4cdbbbe3d066..309cd595d37d 100644 --- a/fs/btrfs/btrfs.c +++ b/fs/btrfs/btrfs.c @@ -246,16 +246,17 @@ int btrfs_read(const char *file, void *buf, loff_t offset, loff_t len, return -EINVAL; } - if (!len) { - ret = btrfs_size(file, &real_size); - if (ret < 0) { - error("Failed to get inode size: %s", file); - return ret; - } - len = real_size; + ret = btrfs_size(file, &real_size); + if (ret < 0) { + error("Failed to get inode size: %s", file); + return ret; } - if (len > real_size - offset) + /* + * If the length is 0 (meaning read the whole file) or the range is + * beyond file size, truncate it to the end of the file. + */ + if (!len || len > real_size - offset) len = real_size - offset; ret = btrfs_file_read(root, ino, offset, len, buf); -- 2.37.1