From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ted Ts'o Subject: Re: uninit_bg compatibility? Date: Tue, 21 Sep 2010 13:59:12 -0400 Message-ID: <20100921175912.GA9597@thunk.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: linux-ext4@vger.kernel.org To: Bo =?iso-8859-1?Q?Brant=E9n?= Return-path: Received: from thunk.org ([69.25.196.29]:55970 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754278Ab0IUR7P (ORCPT ); Tue, 21 Sep 2010 13:59:15 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On Tue, Sep 21, 2010 at 03:28:51PM +0200, Bo Brant=E9n wrote: >=20 > when writing new files to an ext4 file system using the Windows > driver fsck will later complain "Group descriptor nn checksum is > invalid" and I think that is because it used an yet unused block > group without knowing that they can be marked as uninitialized. So I > thought a simple patch would be to mount the file system read-only > if that feature is in use untill the driver is updated with full > write support but I can't find the flag to use, there is no > EXT4_FEATURE_RO_COMPAT_UNINIT_BG so I thought I ask here if anyone > could clear this out. Yeah, this is one where we decided to change the feature to uninit_bg (since that describes the net benefit to the end-user), but we never ended up changing the name of the flag in the source code. The feature flag in question is: #define EXT4_FEATURE_RO_COMPAT_GDT_CSUM 0x0010 I'll note that the Windows driver must not be checking the feature flags, since the whole point of RO_COMPAT flags is that if a file system implementation (such as the Windows drivers) sees an RO_COMPAT flag it doesn't understand, it's supposed to treat the file system as read-only. - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html