From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:33586 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933801AbeGAQYy (ORCPT ); Sun, 1 Jul 2018 12:24:54 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Chad Austin , Miklos Szeredi Subject: [PATCH 4.9 021/101] fuse: atomic_o_trunc should truncate pagecache Date: Sun, 1 Jul 2018 18:21:07 +0200 Message-Id: <20180701160757.989301182@linuxfoundation.org> In-Reply-To: <20180701160757.138608453@linuxfoundation.org> References: <20180701160757.138608453@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Miklos Szeredi commit df0e91d488276086bc07da2e389986cae0048c37 upstream. Fuse has an "atomic_o_trunc" mode, where userspace filesystem uses the O_TRUNC flag in the OPEN request to truncate the file atomically with the open. In this mode there's no need to send a SETATTR request to userspace after the open, so fuse_do_setattr() checks this mode and returns. But this misses the important step of truncating the pagecache. Add the missing parts of truncation to the ATTR_OPEN branch. Reported-by: Chad Austin Fixes: 6ff958edbf39 ("fuse: add atomic open+truncate support") Signed-off-by: Miklos Szeredi Cc: Signed-off-by: Greg Kroah-Hartman --- fs/fuse/dir.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) --- a/fs/fuse/dir.c +++ b/fs/fuse/dir.c @@ -1633,8 +1633,19 @@ int fuse_do_setattr(struct dentry *dentr return err; if (attr->ia_valid & ATTR_OPEN) { - if (fc->atomic_o_trunc) + /* This is coming from open(..., ... | O_TRUNC); */ + WARN_ON(!(attr->ia_valid & ATTR_SIZE)); + WARN_ON(attr->ia_size != 0); + if (fc->atomic_o_trunc) { + /* + * No need to send request to userspace, since actual + * truncation has already been done by OPEN. But still + * need to truncate page cache. + */ + i_size_write(inode, 0); + truncate_pagecache(inode, 0); return 0; + } file = NULL; }