From: Eric Sandeen <sandeen@sandeen.net>
To: Dave Chinner <david@fromorbit.com>
Cc: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>,
Ben Myers <bpm@sgi.com>, xfs-oss <xfs@oss.sgi.com>
Subject: Re: [PATCH] default to 64 bit inodes & add feature flag
Date: Thu, 08 Mar 2012 17:41:16 -0600 [thread overview]
Message-ID: <4F59439C.5040804@sandeen.net> (raw)
In-Reply-To: <20120308233953.GP5091@dastard>
On 3/8/12 5:39 PM, Dave Chinner wrote:
> On Thu, Mar 08, 2012 at 10:38:32AM -0600, Ben Myers wrote:
>> On Thu, Mar 08, 2012 at 09:42:21AM -0600, Eric Sandeen wrote:
>>> So, after thinking about this (and talking on irc) some more, I'm
>>> not convinced that a feature flag is the way to go.
>>>
>>> If we set a feature flag, suddenly old filesystems with 64-bit
>>> inodes will grow a new feature, and this will force a userspace
>>> upgrade - but there is no real new feature. This seems like a bad
>>> idea. My original patch (which Dave responded to with this one)
>>> simply made inode64 default, with no feature flags.
>>>
>>> Unless someone has a really compelling argument for the flag,
>>> I'm thinking this is the wrong approach after all.
>>>
>>> Perhaps I should resend the just-make-it-default patch.
>>>
>>> Comments?
>>
>> Ew! Forcing a userspace upgrade is not desireable. Since we would only
>> want to set the feature bit if userspace were already upgraded, and only
>> if there are 64 bit inos... How about two bits: one is set by mkfs and
>> checked by the kernel to see if it is ok to set the other. ;)
>>
>> The first bit could also act as 'now its ok to default to inode64'.
>
> Too complex, IMO. Just add an xfs_admin command to set the inode64
> feature bit. That then overrides the inode64/inode32 mount option,
> and guarantees that the user has already upgraded userspace.
>
> i.e. the mount options are only valid if the feature bit it not set,
> and the feature bit can only be set via xfs_admin after a userspace
> upgrade. Kernels that don't understand the feature bit will refuse
> to mount, keeping in line with the current practise of requiring
> both kernel and userspace upgrades to occur in step to use new
> features....
Yep, I think that's the right path forward (had been thinking along
these lines too, today).
Thanks,
-Eric
> Cheers,
>
> Dave.
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next prev parent reply other threads:[~2012-03-08 23:41 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-07 17:20 [PATCH] default to 64 bit inodes & add feature flag Eric Sandeen
2012-03-07 17:33 ` Josef 'Jeff' Sipek
2012-03-07 18:07 ` Arkadiusz Miśkiewicz
2012-03-08 1:34 ` Dave Chinner
2012-03-08 2:05 ` Eric Sandeen
2012-03-08 15:37 ` Ben Myers
2012-03-08 15:42 ` Eric Sandeen
2012-03-08 16:14 ` Josef 'Jeff' Sipek
2012-03-08 16:38 ` Ben Myers
2012-03-08 23:39 ` Dave Chinner
2012-03-08 23:41 ` Eric Sandeen [this message]
2012-03-09 2:08 ` Ben Myers
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