From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752644Ab2LQONa (ORCPT ); Mon, 17 Dec 2012 09:13:30 -0500 Received: from relay.parallels.com ([195.214.232.42]:58955 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751935Ab2LQON3 convert rfc822-to-8bit (ORCPT ); Mon, 17 Dec 2012 09:13:29 -0500 Message-ID: <50CF288E.8060002@parallels.com> Date: Mon, 17 Dec 2012 18:13:34 +0400 From: "Maxim V. Patlasov" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Brian Foster CC: , , , , , Subject: Re: [PATCH 5/6] fuse: truncate file if async dio failed References: <20121214151424.27155.45971.stgit@maximpc.sw.ru> <20121214152113.27155.58793.stgit@maximpc.sw.ru> <50CB8931.2000305@redhat.com> In-Reply-To: <50CB8931.2000305@redhat.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8BIT X-Originating-IP: [10.30.17.2] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, 12/15/2012 12:16 AM, Brian Foster пишет: > On 12/14/2012 10:21 AM, Maxim V. Patlasov wrote: >> The patch improves error handling in fuse_direct_IO(): if we successfully >> submitted several fuse requests on behalf of synchronous direct write >> extending file and some of them failed, let's try to do our best to clean-up. >> >> Signed-off-by: Maxim Patlasov >> --- >> fs/fuse/file.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++-- >> 1 files changed, 53 insertions(+), 2 deletions(-) >> >> diff --git a/fs/fuse/file.c b/fs/fuse/file.c >> index 05eed23..b6e9b8d 100644 >> --- a/fs/fuse/file.c >> +++ b/fs/fuse/file.c >> @@ -2340,6 +2340,53 @@ int fuse_notify_poll_wakeup(struct fuse_conn *fc, >> return 0; >> } >> >> +static void fuse_do_truncate(struct file *file) >> +{ >> + struct fuse_file *ff = file->private_data; >> + struct inode *inode = file->f_mapping->host; >> + struct fuse_conn *fc = get_fuse_conn(inode); >> + struct fuse_req *req; >> + struct fuse_setattr_in inarg; >> + struct fuse_attr_out outarg; >> + int err; >> + >> + req = fuse_get_req_nopages(fc); >> + if (IS_ERR(req)) { >> + printk(KERN_WARNING "failed to allocate req for truncate " >> + "(%ld)\n", PTR_ERR(req)); >> + return; >> + } >> + >> + memset(&inarg, 0, sizeof(inarg)); >> + memset(&outarg, 0, sizeof(outarg)); >> + >> + inarg.valid |= FATTR_SIZE; >> + inarg.size = i_size_read(inode); >> + >> + inarg.valid |= FATTR_FH; >> + inarg.fh = ff->fh; >> + >> + req->in.h.opcode = FUSE_SETATTR; >> + req->in.h.nodeid = get_node_id(inode); >> + req->in.numargs = 1; >> + req->in.args[0].size = sizeof(inarg); >> + req->in.args[0].value = &inarg; >> + req->out.numargs = 1; >> + if (fc->minor < 9) >> + req->out.args[0].size = FUSE_COMPAT_ATTR_OUT_SIZE; >> + else >> + req->out.args[0].size = sizeof(outarg); >> + req->out.args[0].value = &outarg; >> + >> + fuse_request_send(fc, req); >> + err = req->out.h.error; >> + fuse_put_request(fc, req); >> + >> + if (err) >> + printk(KERN_WARNING "failed to truncate to %lld with error " >> + "%d\n", i_size_read(inode), err); >> +} >> + > fuse_do_truncate() looks fairly close to fuse_do_setattr(). Is there any > reason we couldn't make fuse_do_setattr() non-static, change the dentry > parameter to an inode and use that? fuse_do_setattr() performs extra checks that fuse_do_truncate() needn't. Some of them are harmless, some not: fuse_allow_task() may return 0 if task credentials changed. E.g. super-user successfully opened a file, then setuid(other_user_uid), then write(2) to the file. write(2) doesn't check uid, but fuse_do_truncate() - via fuse_allow_task() - does. This non-POSIX behaviour (ftruncate(2) returning -1 with errno==EACCES) was introduced long time ago: > commit e57ac68378a287d6336d187b26971f35f7ee7251 > Author: Miklos Szeredi > Date: Thu Oct 18 03:06:58 2007 -0700 > > fuse: fix allowing operations > > The following operation didn't check if sending the request was > allowed: > > setattr > listxattr > statfs > > Some other operations don't explicitly do the check, but VFS calls > ->permission() which checks this. > > Signed-off-by: Miklos Szeredi > Signed-off-by: Andrew Morton > Signed-off-by: Linus Torvalds and I'm not sure whether it was done intentionally or not. Maybe Miklos could shed some light on it... Thanks, Maxim