From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933996AbdKAVWN (ORCPT ); Wed, 1 Nov 2017 17:22:13 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:35090 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933977AbdKAVWL (ORCPT ); Wed, 1 Nov 2017 17:22:11 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Jan Kara , "Theodore Ts'o" , stable@vger.kernel.org#3.8+, Willy Tarreau Subject: [PATCH 3.10 041/139] ext4: fix SEEK_HOLE/SEEK_DATA for blocksize < pagesize Date: Wed, 1 Nov 2017 22:17:41 +0100 Message-Id: <1509571159-4405-42-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1509571159-4405-1-git-send-email-w@1wt.eu> References: <1509571159-4405-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jan Kara commit fcf5ea10992fbac3c7473a1db33d56a139333cd1 upstream. ext4_find_unwritten_pgoff() does not properly handle a situation when starting index is in the middle of a page and blocksize < pagesize. The following command shows the bug on filesystem with 1k blocksize: xfs_io -f -c "falloc 0 4k" \ -c "pwrite 1k 1k" \ -c "pwrite 3k 1k" \ -c "seek -a -r 0" foo In this example, neither lseek(fd, 1024, SEEK_HOLE) nor lseek(fd, 2048, SEEK_DATA) will return the correct result. Fix the problem by neglecting buffers in a page before starting offset. Reported-by: Andreas Gruenbacher Signed-off-by: Theodore Ts'o Signed-off-by: Jan Kara CC: stable@vger.kernel.org # 3.8+ Signed-off-by: Willy Tarreau --- fs/ext4/file.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/ext4/file.c b/fs/ext4/file.c index ec9770f..d490d6e 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -382,6 +382,8 @@ static int ext4_find_unwritten_pgoff(struct inode *inode, lastoff = page_offset(page); bh = head = page_buffers(page); do { + if (lastoff + bh->b_size <= startoff) + goto next; if (buffer_uptodate(bh) || buffer_unwritten(bh)) { if (whence == SEEK_DATA) @@ -396,6 +398,7 @@ static int ext4_find_unwritten_pgoff(struct inode *inode, unlock_page(page); goto out; } +next: lastoff += bh->b_size; bh = bh->b_this_page; } while (bh != head); -- 2.8.0.rc2.1.gbe9624a