Re: Building a brtfs filesystem < 70M?

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

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?

Thanks,
Gui