Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754343Ab3F0W2E (ORCPT ); Thu, 27 Jun 2013 18:28:04 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:39254 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754103Ab3F0W2C (ORCPT ); Thu, 27 Jun 2013 18:28:02 -0400 Date: Thu, 27 Jun 2013 15:28:00 -0700 From: Andrew Morton To: Paul Clements Cc: kernel list , "nbd-general@lists.sourceforge.net" Subject: Re: [PATCH] nbd: correct disconnect behavior Message-Id: <20130627152800.494a6043607a62feb35e9739@linux-foundation.org> In-Reply-To: References: <20130619210918.DF616222D8@clements> <20130626162107.9237360f7646ec25f23cf5aa@linux-foundation.org> X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2863 Lines: 75 On Thu, 27 Jun 2013 18:20:37 -0400 Paul Clements wrote: > > --- a/drivers/block/nbd.c > > > +++ b/drivers/block/nbd.c > > > @@ -623,6 +623,8 @@ static int __nbd_ioctl(struct block_device *bdev, > > struct nbd_device *nbd, > > > if (!nbd->sock) > > > return -EINVAL; > > > > > > + nbd->disconnect = 1; > > > + > > > nbd_send_req(nbd, &sreq); > > > return 0; > > > } > > > @@ -654,6 +656,7 @@ static int __nbd_ioctl(struct block_device *bdev, > > struct nbd_device *nbd, > > > nbd->sock = SOCKET_I(inode); > > > if (max_part > 0) > > > bdev->bd_invalidated = 1; > > > + nbd->disconnect = 0; /* we're connected > > now */ > > > return 0; > > > } else { > > > fput(file); > > > @@ -742,6 +745,8 @@ static int __nbd_ioctl(struct block_device *bdev, > > struct nbd_device *nbd, > > > set_capacity(nbd->disk, 0); > > > if (max_part > 0) > > > ioctl_by_bdev(bdev, BLKRRPART, 0); > > > + if (nbd->disconnect) /* user requested, ignore socket > > errors */ > > > + return 0; > > > return nbd->harderror; > > > } > > > > hm, how does nbd work... Hard to tell as nothing seems to be documented > > anywhere :( > > > > I think most people look at the nbd-client to see. :) > > But I will work on some docs for the ioctls... > > Briefly, though, it goes something like this: > > nbd-client and nbd-server negotiate parameters, including the server > telling the client how big the export is > > Then the nbd-client does a series of ioctls to set up the device: > > NBD_SET_SIZE - set the size of the device > NBD_SET_SOCK - tell the kernel which socket to use > NBD_DO_IT - this ioctl lasts for the life of the device and causes > nbd-client to go into a receive loop, handling I/O replies from the > nbd-server > > NBD_DISCONNECT, meanwhile, can be called from a separate thread (usually > "nbd-client -d" calls it). This requests a disconnect of the device. OK, but. "Would it be safer to clear ->disconnect in NBD_DO_IT?" If not safer, would it be cleaner? > > The cool kids are using bool lately ;) > > > > Hey, maybe I want to be able to compile with gcc 2.7.2 ? :) Sob, I miss 2.7.2. It was a good 50% faster than the new improved models. But I don't think this yearning makes us cool. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/