From: Jeff Mahoney <jeffm@suse.com>
To: dsterba@suse.cz, linux-btrfs@vger.kernel.org, clmason@fusionio.com
Subject: Re: [patch 1/9] btrfs: add ioctls to query/change feature bits online
Date: Wed, 18 Sep 2013 10:29:22 -0400 [thread overview]
Message-ID: <5239B8C2.4070107@suse.com> (raw)
In-Reply-To: <20130918141459.GA6810@twin.jikos.cz>
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On 9/18/13 10:14 AM, David Sterba wrote:
> On Mon, Sep 16, 2013 at 02:19:11PM -0400, Jeff Mahoney wrote:
>> There are some feature bits that require no offline setup and can
>> be enabled online. I've only reviewed extended irefs, but there will
>> probably be more.
>
> Each feature bit being set online has to be treated separately regarding
> safety of the data in flight.
>
> You can set extended irefs online, there's only one place where the bit
> is checked (if the hadlink count overflows the leaf), it's ok to set the
> bit anytime before or after and it will not break anything.
>
> Skinny metadata bit is checked all over the place and I'm not sure it's
> ok to set it on after some portion of data has been processed in the
> non-skinny mode.
>
> 'default_subvol', lzo are ok, the rest depends on mkfs and can't be
> modified online at all.
>
> So, for skinny metadata it's most likely required to set the bit in a
> delayed manner and schedule it eg. to post-commit time.
Yep, that's why extended_iref is the only one I've enabled so far. Other
features with harder requirements are going to need to be handled
explicitly.
> The sysfs and ioctl interface looks ok to me.
Great, thanks.
-Jeff
--
Jeff Mahoney
SUSE Labs
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next prev parent reply other threads:[~2013-09-18 14:29 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-16 18:19 [patch 0/9 v3] add ability to query/change feature bits online Jeff Mahoney
2013-09-16 18:19 ` [patch 1/9] btrfs: add ioctls " Jeff Mahoney
2013-09-18 14:05 ` David Sterba
2013-09-18 14:14 ` David Sterba
2013-09-18 14:29 ` Jeff Mahoney [this message]
2013-09-16 18:19 ` [patch 2/9] btrfs: use btrfs_commit_transaction when setting fslabel Jeff Mahoney
2013-09-16 18:19 ` [patch 3/9] kobject: introduce kobj_completion Jeff Mahoney
2013-09-16 18:19 ` [patch 4/9] btrfs: export supported featured to sysfs Jeff Mahoney
2013-09-16 18:19 ` [patch 5/9] btrfs: add per-super attributes " Jeff Mahoney
2013-09-16 18:19 ` [patch 6/9] btrfs: publish per-super features " Jeff Mahoney
2013-09-16 18:19 ` [patch 7/9] btrfs: add publishing of unknown features in sysfs Jeff Mahoney
2013-09-16 18:19 ` [patch 8/9] btrfs: add ability to change features via sysfs Jeff Mahoney
2013-09-16 18:19 ` [patch 9/9] btrfs: use feature attribute names to print better error messages Jeff Mahoney
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