From: Chris Mason <chris.mason@oracle.com>
To: "Yan, Zheng" <yanzheng@21cn.com>
Cc: Josef Bacik <josef@redhat.com>,
linux-btrfs <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH] Btrfs: do not loop through raid types when looking for free extent
Date: Mon, 13 Dec 2010 20:59:51 -0500 [thread overview]
Message-ID: <1292291723-sup-2491@think> (raw)
In-Reply-To: <AANLkTimObyLj=f7W9jdqxd1f7tQ9HVeUpsKRRgKKkLwn@mail.gmail.com>
Excerpts from Yan, Zheng's message of 2010-12-13 20:54:12 -0500:
> On Tue, Dec 14, 2010 at 9:33 AM, Chris Mason <chris.mason@oracle.com>=
wrote:
> > Excerpts from Yan, Zheng's message of 2010-11-16 20:38:23 -0500:
> >> On Wed, Nov 17, 2010 at 5:22 AM, Josef Bacik <josef@redhat.com> wr=
ote:
> >> > There is a bug in find_free_extent where if we don't find a free=
extent in the
> >> > raid type we are looking for, we loop through to the next raid t=
ype. =C2=A0This is
> >> > not ok since we need to make sure we honor the raid types we are=
given. =C2=A0So
> >> > instead kill this check and get the proper index for the raid ty=
pe we want from
> >> > the allocator. =C2=A0Thanks,
> >> >
> >>
> >> Loop through raid types is for handling failure in the middle of r=
aid type
> >> conversion.
> >
> > The problem is that nothing prevents it from looping back to a raid=
0
> > chunk when we really want raid1 or raid10. =C2=A0And mkfs leaves be=
hind a
> > small raid0 chunk (4MB) that is uses as it assembles all the device=
s.
>=20
> check code at end of btrfs_read_block_groups, it prevents allocating
> from raid0 when there are mirrored block groups.
We're still allocating from them though. It's a big problem when we
mount degraded.
-chris
>=20
> >
> > I confirmed that we often use the small raid0 chunk even in raid1 o=
r
> > raid10.
> >
> > Please take a look at this commit:
> >
> > http://git.kernel.org/?p=3Dlinux/kernel/git/mason/btrfs-unstable.gi=
t;a=3Dcommit;h=3D83a50de97fe96aca82389e061862ed760ece2283
> >
> > -chris
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-btr=
fs" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at =C2=A0http://vger.kernel.org/majordomo-info.=
html
> >
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prev parent reply other threads:[~2010-12-14 1:59 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-16 21:22 [PATCH] Btrfs: do not loop through raid types when looking for free extent Josef Bacik
2010-11-17 1:37 ` Yan, Zheng
2010-11-17 2:31 ` Josef Bacik
2010-11-17 1:38 ` Yan, Zheng
2010-12-14 1:33 ` Chris Mason
2010-12-14 1:54 ` Yan, Zheng
2010-12-14 1:59 ` Chris Mason [this message]
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