Re: Building a brtfs filesystem < 70M?

["quwenruo@cn.fujitsu.com" <quwenruo@cn.fujitsu.com>]

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On Tue, 11 Mar 2014 09:37:00 -0700, Zach Brown wrote:
>> 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.
>> mkfs.btrfs -b 104857600 -r rootfs rootfs.btrfs
> Honestly, the path of least resistance is probably to avoid the -r
> option all together.  As you've found, it's not reliable.
>
> I'd take the time to roll the infrastrcture to populate the image by
> writing to a mounted image with the kernel code.
>
> - z
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I although agree with the mount + cp(kernel) way to populate the filesystem.
Also I think the implement of "-r" should be somewhat like mount+cp 
other than the current way,
since the userland implement is noticeably slow than kernel way.

Cc:Donggeun Kim
I also wonder why "-r" option is needed, since IMO the "-r" options is 
only needed
if the filesystem is full readonly and must be populated on 
initialization like squashfs.
And since btrfs is a filesystem that can be read and write,
the "-r" option is not somewhat needed.

So I prefer to remove the "-r" option.


Thanks
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