From: Ted Ts'o <tytso@mit.edu>
To: "Bo Brantén" <bosse@acc.umu.se>
Cc: linux-ext4@vger.kernel.org
Subject: Re: uninit_bg compatibility?
Date: Tue, 21 Sep 2010 13:59:12 -0400 [thread overview]
Message-ID: <20100921175912.GA9597@thunk.org> (raw)
In-Reply-To: <Pine.A41.4.64.1009211500110.1245260@stalin.acc.umu.se>
On Tue, Sep 21, 2010 at 03:28:51PM +0200, Bo Brantén wrote:
>
> 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
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prev parent reply other threads:[~2010-09-21 17:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-21 13:28 uninit_bg compatibility? Bo Brantén
2010-09-21 17:00 ` Andreas Dilger
2010-09-21 17:59 ` Ted Ts'o [this message]
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