From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josef Bacik Subject: Re: [PATCH] Btrfs: add support for mixed data+metadata block groups V3 Date: Thu, 21 Oct 2010 21:37:02 -0400 Message-ID: <20101022013701.GH30906@dhcp231-156.rdu.redhat.com> References: <1286452263-1635-1-git-send-email-josef@redhat.com> <201010220009.26464.diegocg@gmail.com> <20101022010521.GG30906@dhcp231-156.rdu.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Cc: Josef Bacik , Mitch Harder , linux-btrfs To: C Anthony Risinger Return-path: In-Reply-To: List-ID: On Thu, Oct 21, 2010 at 08:32:12PM -0500, C Anthony Risinger wrote: > On Thu, Oct 21, 2010 at 8:05 PM, Josef Bacik wrote= : > > On Thu, Oct 21, 2010 at 05:21:06PM -0500, Mitch Harder wrote: > >> On Thu, Oct 21, 2010 at 5:09 PM, Diego Calleja = wrote: > >> > On Jueves, 21 de Octubre de 2010 17:46:58 David Nicol escribi=F3= : > >> >> Does this mixing constitute a forbidden change of on-disk forma= t, and > >> >> if not how not? > >> > > >> > It doesn't need a format change. The difference between a data a= nd > >> > a metadata block group is just an allocation hint AFAIK. > >> > -- > >> > To unsubscribe from this list: send the line "unsubscribe linux-= btrfs" in > >> > the body of a message to majordomo@vger.kernel.org > >> > More majordomo info at =A0http://vger.kernel.org/majordomo-info.= html > >> > > >> > >> Let me know if the problems with an un-patched kernel were un-expe= cted. > >> > >> I can provide more information on the crash when booting an older = kernel. > > > > Nope they are expected, it's not a disk format change, but older ke= rnels won't > > deal with mixed block groups. >=20 > When something like this goes mainline, is it used by default/automat= ically? >=20 > I ask because I maintain a btrfs-based rollback initramfs hook [1], > and am currently updating it for extlinux, enabling kernel-level > system rollbacks via `btrfs set-default` + reboot (or maybe > `kexec`)... >=20 > rolling back to an old kernel will then blow up my machine > (figuratively of course :-)? > The only way you get this feature is if you mkfs with the feature enabl= ed, and is only meant for small filesystems (1 gig or smaller). Thanks, Josef -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html