From mboxrd@z Thu Jan 1 00:00:00 1970 From: 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> References: <20181121024400.4346-1-devel@etsukata.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20181121024400.4346-1-devel@etsukata.com> Sender: linux-btrfs-owner@vger.kernel.org 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 List-Id: linux-f2fs-devel.lists.sourceforge.net 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