From: Alan Stern Subject: Re: Weird I/O errors with USB hard drive not remounting filesystem readonly Date: Mon, 23 Nov 2009 13:20:26 -0500 (EST) Message-ID: References: <20091123160914.GG15679@duck.suse.cz> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: tmhikaru@gmail.com, , , Jens Axboe , , To: Jan Kara Return-path: Received: from iolanthe.rowland.org ([192.131.102.54]:55388 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753759AbZKWSU0 (ORCPT ); Mon, 23 Nov 2009 13:20:26 -0500 In-Reply-To: <20091123160914.GG15679@duck.suse.cz> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon, 23 Nov 2009, Jan Kara wrote: > On Mon 23-11-09 10:06:03, Alan Stern wrote: > > On Mon, 23 Nov 2009, Jan Kara wrote: > > > > > Yeah, from what you write, it looks like USB enclosure is at fault (or it > > > could still be your USB controller but I doubt it). It's still a bit > > > bothering that the error reported by the drive was not properly propagated > > > up to VFS. Either it's some block layer retry/ignore magic that I missed or > > > we ignore errors from block layer in some place. > > > > Is there any interest in tracking this down? It's not hard to find out > > what low-level errors are being reported and to generate them on demand > > with an emulated USB disk drive. > Well, if you could provide me with the patch, I could try to track down > why the errors aren't propagated... It would be interesting because if it's > not some retry logic in block layer, it's a bug in VFS ;). I can't provide a patch without first knowing what the errors are. The way to find out is to use usbmon. See Documentation/usb/usbmon.txt for instructions. Alan Stern