From: Dave Chinner <david@fromorbit.com>
To: David Howells <dhowells@redhat.com>
Cc: viro@ZenIV.linux.org.uk, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org
Subject: Re: [PATCH] Rearrange i_flags to be consistent with FS_IOC_GETFLAGS
Date: Wed, 7 Jul 2010 11:55:30 +1000 [thread overview]
Message-ID: <20100707015530.GE25018@dastard> (raw)
In-Reply-To: <5045.1278459925@redhat.com>
On Wed, Jul 07, 2010 at 12:45:25AM +0100, David Howells wrote:
> Dave Chinner <david@fromorbit.com> wrote:
>
> > I'd prefer generic flags are not dependent on fixed values from a
> > specific filesystem several layers down the storage stack.
>
> They're not so dependent.
History says otherwise. :)
> They're based on the FS_IOC_[GS]ETFLAGS ioctl which
> even XFS translates its flags for.
Sure, because the ioctl flags values are derived
from the ext2 on-disk format flags and hence don't match anything
XFS related at all.
> These ioctl flags must now remain
> invariant. Whilst they might have originated as Ext2/3/4 flags, they're now
> independent of that.
Yes, the ioctl flags must remain invariant. OTOH, the generic inode
flags (S_*) have no such invariant requirement and have a history of
frequent change. IMO, that means some flags should not be tied to
the value of a specific subsystem just so a subsystem specific
optimisation can be made. It just seems like a dangerous layering
violation to be making...
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
prev parent reply other threads:[~2010-07-07 1:55 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-05 15:43 [PATCH] Rearrange i_flags to be consistent with FS_IOC_GETFLAGS David Howells
2010-07-05 15:54 ` Eric Sandeen
2010-07-05 17:27 ` tytso
2010-07-06 0:10 ` Dave Chinner
2010-07-06 13:40 ` David Howells
2010-07-06 23:03 ` Dave Chinner
2010-07-06 23:45 ` David Howells
2010-07-07 1:55 ` Dave Chinner [this message]
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