Re: Building a brtfs filesystem < 70M?

[Gui Hecheng <guihc.fnst@cn.fujitsu.com>]

On Mon, 2014-03-10 at 20:16 -0700, Saul Wold wrote:
> On 03/10/2014 07:38 PM, Gui Hecheng wrote:
> > On Mon, 2014-03-10 at 16:25 -0700, Saul Wold wrote:
> >> Hi There
> >>
> >> There seems to be an issue if we try to build a btrfs based FS that is
> >> less than 70M, we get the following assertion failure:
> >>
> >> mkfs.btrfs: extent-tree.c:2682: btrfs_reserve_extent: Assertion `!(ret)'
> >> failed.
> >>
> >> I tried to do a search on this and did not find anything obvious.
> >>
> >> Further, if I do build a 70M image, it will not mount until I get to I
> >> increase  the about 100M!
> >>
> >> # mount -o loop -v rootfs.btrfs mnt
> >> mount: wrong fs type, bad option, bad superblock on /dev/loop0,
> >>          missing codepage or helper program, or other error
> >>
> >>          In some cases useful info is found in syslog - try
> >>          dmesg | tail or so.
> >>
> >> I can provide a small rootfs (~4M) example if needed
> >>
> >> Builds and mounts correct:
> >> mkfs.btrfs -b 104857600 -r rootfs rootfs.btrfs
> >>
> >> Builds, but does not mount:
> >> mkfs.btrfs -b 73400320 -r rootfs rootfs.btrfs
> >>
> >> Does not build, gives the above assertion error:
> >> mkfs.btrfs -b 10889216 -r rootfs rootfs.btrfs
> >>
> >>
> >> Thanks
> >>
> > Hi Saul,
> > Sorry, I'm not able to reproduce your problem...
> > Are you running the latest btrfs-progs from david's branch?
> >
> Yes, I am building it from git using master I think, git hash: 
> 8cae1840afb3ea44dcc298f32983e577480dfee4
> 
> I tried both with and without the -M as cwillu suggested, still no joy, 
> I can send some the rootfs I am using to see if is's something specific.
> 
> Here's the full failure:
> 
> $ tmp/sysroots/x86_64-linux/usr/bin/mkfs.btrfs -M -b 10889216 -r 
> tmp/work/qemux86_64-poky-linux/core-image-minimal/1.0-r0/rootfs rootfs.btrfs
> SMALL VOLUME: forcing mixed metadata/data groups
> SMALL VOLUME: forcing mixed metadata/data groups
> 
> WARNING! - Btrfs v3.12-dirty IS EXPERIMENTAL
> WARNING! - see http://btrfs.wiki.kernel.org before using
> 
> Turning ON incompat feature 'mixed-bg': mixed data and metadata block groups
> Turning ON incompat feature 'extref': increased hardlink limit per file 
> to 65536
> Created a data/metadata chunk of size 8388608
> fs created label (null) on rootfs.btrfs
> 	nodesize 4096 leafsize 4096 sectorsize 4096 size 180.00MiB
> Btrfs v3.12-dirty
> scandir for 
> tmp/work/qemux86_64-poky-linux/core-image-minimal/1.0-r0/rootfs failed: 
> No such file or directory
> unable to traverse_directory
> Making image is aborted.
> mkfs.btrfs: mkfs.c:1592: main: Assertion `!(ret)' failed.
> Aborted (core dumped)
> 
> 
> Thanks for the help!
> 
> Sau!
> 
I think the output really tells us the problem: the mkfs '-r' option
requires a 'directory' as an arg.
But still it should not abort with 'core dumped', I would be glad to
make it more friendly.

-Gui
> 
> > Thanks,
> > Gui
> >
> >