Re: Errors in btrfsck after converting ext2 FS to btrfs.

[Prasad Joshi <prasadjoshi124@gmail.com>]

On Mon, Oct 19, 2009 at 7:56 AM, Yan, Zheng <yanzheng@21cn.com> wrote:
> On Sun, Oct 18, 2009 at 10:35 PM, Prasad Joshi <prasadjoshi124@gmail.=
com> wrote:
>> Hi,
>>
>> I tried using the btrfs-convert utility to convert the ext2 fs to
>> btrfs. After the conversion was over, just to verify the correctness
>> of operation, ran btrfsck on the device. It showed errors 800. I am
>> not sure what does it mean, so thought of repoting it on mailing lis=
t.
>>
>> # btrfsck /dev/sdb
>> root 256 inode 257 errors 800
>> found 1105965056 bytes used err is 1
>> total csum bytes: 192576
>> total tree bytes: 459956224
>> total fs tree bytes: 449585152
>> btree space waste bytes: 191448023
>> file data blocks allocated: 843206656
>> referenced 843206656
>> Btrfs v0.19-3-g6f3cf25-dirty
>
> "root 256 inode 257" is the ext2 image file. Checksum for file extent=
s in
> the ext2 image file is very special, so btrfsck treat it as error. Th=
is error
> has no harm, =A0it will go away after deleting the ext2 image file.

OKay thanks.

>
>>
>> I also found that, after the conversion of FS from ext2 to btrfs
>> %usage gone up drastically. I mean before the conversion ext2 FS was
>> 22% full but then converted btrfs is 64% used.
>>
>> Steps Followed
>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>> 1. Created an ext2 filesystem of size 2G
>> 2. Created about 178 files of size 1M in a directory. FS was 11% ful=
l
>> after the operation.
>> 3. In another directory create near about 1 Lac files of very small
>> size (2K). I kept on creating files till the number of available
>> inodes were exhausted.
>>
>> # fsck /dev/sdb
>> fsck 1.41.3 (12-Oct-2008)
>> e2fsck 1.41.3 (12-Oct-2008)
>> /dev/sdb: clean, 131072/131072 files, 188721/524288 blocks
>>
>> At this point df -kh output showed that FS as 22% full
>>
>> 4. Tried to convert the ext2 FS to btrfs using btrfs-convert utility
>>
>> # btrfs-convert /dev/sdb
>> creating btrfs metadata.
>> creating ext2fs image file.
>> cleaning up system chunk.
>> conversion complete.
>>
>> 5. Ran btrfsck.
>>
>> 6. Mounted the file system
>>
>> # df -kh
>> Filesystem=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 Size=A0 Used Avail Use% =
Mounted on
>> ....
>> ....
>> tmpfs=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 251M=A0 104K=A0=
 251M=A0=A0 1% /dev/shm
>> /dev/sdb=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 2.0G=A0 1.3G=A0 740M=
=A0 64% /mnt/fs
>>
>> As you can see df displays FS is 64% full, when infact before
>> conversion it was onlly 22% full. Why is so much increase in
>> percentage usage?
>
> This is a accounting bug, it's already fixed in btrfs-progs-unstable =
tree.

I am using the latest btrfs-progs-unstable tree. I had cloned the git
repository, I used the same updated repository. Is there any other
repository than the one declared on Wiki Page?

I used cloned repo from
git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-progs-unstabl=
e.git

Thanks,
Prasad

>
> Yan, Zheng
>
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