Return-Path: Received: from mail-pl1-f194.google.com ([209.85.214.194]:42869 "EHLO mail-pl1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726483AbeKUNQr (ORCPT ); Wed, 21 Nov 2018 08:16:47 -0500 Received: by mail-pl1-f194.google.com with SMTP id x21-v6so3191026pln.9 for ; Tue, 20 Nov 2018 18:44:25 -0800 (PST) From: Eiichi Tsukata To: andi@firstfloor.org, Chris Mason , Josef Bacik , David Sterba , "Theodore Ts'o" , Andreas Dilger , Jaegeuk Kim , Chao Yu , Miklos Szeredi , Bob Peterson , Andreas Gruenbacher , Alexander Viro , linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, cluster-devel@redhat.com, linux-unionfs@vger.kernel.org Cc: Eiichi Tsukata Subject: [PATCH v1 2/4] ext4: fix race between llseek SEEK_END and write Date: Wed, 21 Nov 2018 11:43:58 +0900 Message-Id: <20181121024400.4346-3-devel@etsukata.com> In-Reply-To: <20181121024400.4346-1-devel@etsukata.com> References: <20181121024400.4346-1-devel@etsukata.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-ext4-owner@vger.kernel.org List-ID: Implement individual lock for SEEK_END for ext4 which directly calls generic_file_llseek_size(). Signed-off-by: Eiichi Tsukata --- fs/ext4/file.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 69d65d49837b..6479f3066043 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -477,6 +477,16 @@ loff_t ext4_llseek(struct file *file, loff_t offset, int whence) default: return generic_file_llseek_size(file, offset, whence, maxbytes, i_size_read(inode)); + case SEEK_END: + /* + * protects against inode size race with write so that llseek + * doesn't see inode size being updated in generic_perform_write + */ + inode_lock_shared(inode); + offset = generic_file_llseek_size(file, offset, whence, + maxbytes, i_size_read(inode)); + inode_unlock_shared(inode); + return offset; case SEEK_HOLE: inode_lock_shared(inode); offset = iomap_seek_hole(inode, offset, &ext4_iomap_ops); -- 2.19.1