From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932687Ab3JKTlt (ORCPT ); Fri, 11 Oct 2013 15:41:49 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:46323 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932648Ab3JKTlo (ORCPT ); Fri, 11 Oct 2013 15:41:44 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Maxim Patlasov , Miklos Szeredi Subject: [ 073/135] fuse: fix fallocate vs. ftruncate race Date: Fri, 11 Oct 2013 12:39:14 -0700 Message-Id: <20131011193953.216505146@linuxfoundation.org> X-Mailer: git-send-email 1.8.4.3.gca3854a In-Reply-To: <20131011193945.181603934@linuxfoundation.org> References: <20131011193945.181603934@linuxfoundation.org> User-Agent: quilt/0.60-5.1.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.11-stable review patch. If anyone has any objections, please let me know. ------------------ From: Maxim Patlasov commit 0ab08f576b9e6a6b689fc6b4e632079b978e619b upstream. A former patch introducing FUSE_I_SIZE_UNSTABLE flag provided detailed description of races between ftruncate and anyone who can extend i_size: > 1. As in the previous scenario fuse_dentry_revalidate() discovered that i_size > changed (due to our own fuse_do_setattr()) and is going to call > truncate_pagecache() for some 'new_size' it believes valid right now. But by > the time that particular truncate_pagecache() is called ... > 2. fuse_do_setattr() returns (either having called truncate_pagecache() or > not -- it doesn't matter). > 3. The file is extended either by write(2) or ftruncate(2) or fallocate(2). > 4. mmap-ed write makes a page in the extended region dirty. This patch adds necessary bits to fuse_file_fallocate() to protect from that race. Signed-off-by: Maxim Patlasov Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman --- fs/fuse/file.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -2467,6 +2467,7 @@ static long fuse_file_fallocate(struct f { struct fuse_file *ff = file->private_data; struct inode *inode = file->f_inode; + struct fuse_inode *fi = get_fuse_inode(inode); struct fuse_conn *fc = ff->fc; struct fuse_req *req; struct fuse_fallocate_in inarg = { @@ -2495,6 +2496,9 @@ static long fuse_file_fallocate(struct f } } + if (!(mode & FALLOC_FL_KEEP_SIZE)) + set_bit(FUSE_I_SIZE_UNSTABLE, &fi->state); + req = fuse_get_req_nopages(fc); if (IS_ERR(req)) { err = PTR_ERR(req); @@ -2527,6 +2531,9 @@ static long fuse_file_fallocate(struct f fuse_invalidate_attr(inode); out: + if (!(mode & FALLOC_FL_KEEP_SIZE)) + clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state); + if (lock_inode) mutex_unlock(&inode->i_mutex);