Btrfs devel - Dec 2008 - btrfs: Problem with multi device mounting

Hi,

This problem happens when mkfs.btrfs has been executed while
btrfs module was not loaded into the kernel.

I am using the latest commit on btrfs-unstable.
Commit:
c99e905c945c462085c6d64646dc5af0c0a16815

Steps to reproduce:

1) Create a btrfs filesystem while the btrfs module is not yet loaded.

[root@f10-vm1 ~]# uname -a
Linux f10-vm1 2.6.28-rc5 #9 SMP Thu Dec 4 18:09:37 IST 2008 i686 i686
i386 GNU/Linux
[root@f10-vm1 ~]# rmmod btrfs

[root@f10-vm1 ~]# /home/niraj/btrfs/bin/mkfs.btrfs /dev/sdb1 /dev/sdb2
adding device /dev/sdb2 id 2
fs created label (null) on /dev/sdb1
	nodesize 4096 leafsize 4096 sectorsize 4096 size 4.00GB
Btrfs v0.16-25-gd45ee76

2) Try to mount it (this automatically loads btrfs module) :

[root@f10-vm1 ~]# mount -t btrfs /dev/sdb1 /f1
mount: wrong fs type, bad option, bad superblock on /dev/sdb1,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so


Here is the relevant dmesg output:
Btrfs loaded
device fsid 514ee5004d4b722d-ae7cc1f744a0b49f devid 1 transid 9 /dev/sdb1
btrfs: failed to read the system array on sdb1
btrfs: open_ctree failed


Let me know if I can provide more information.


-Niraj
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2008/12/8 Niraj kumar <niraj17@gmail.com>:
> Hi,
>
> This problem happens when mkfs.btrfs has been executed while
> btrfs module was not loaded into the kernel.
>
> I am using the latest commit on btrfs-unstable.
> Commit:
> c99e905c945c462085c6d64646dc5af0c0a16815
>
> Steps to reproduce:
>
> 1) Create a btrfs filesystem while the btrfs module is not yet loaded.
>
> [root@f10-vm1 ~]# uname -a
> Linux f10-vm1 2.6.28-rc5 #9 SMP Thu Dec 4 18:09:37 IST 2008 i686 i686
> i386 GNU/Linux
> [root@f10-vm1 ~]# rmmod btrfs
>
> [root@f10-vm1 ~]# /home/niraj/btrfs/bin/mkfs.btrfs /dev/sdb1 /dev/sdb2
> adding device /dev/sdb2 id 2
> fs created label (null) on /dev/sdb1
>        nodesize 4096 leafsize 4096 sectorsize 4096 size 4.00GB
> Btrfs v0.16-25-gd45ee76
>
> 2) Try to mount it (this automatically loads btrfs module) :
>
> [root@f10-vm1 ~]# mount -t btrfs /dev/sdb1 /f1
> mount: wrong fs type, bad option, bad superblock on /dev/sdb1,
>       missing codepage or helper program, or other error
>       In some cases useful info is found in syslog - try
>       dmesg | tail  or so
>
>
> Here is the relevant dmesg output:
> Btrfs loaded
> device fsid 514ee5004d4b722d-ae7cc1f744a0b49f devid 1 transid 9 /dev/sdb1
> btrfs: failed to read the system array on sdb1
> btrfs: open_ctree failed
>
>
> Let me know if I can provide more information.
>
Please execute ''btrfsctl -a'' before mount.

Yan Zheng
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On Mon, Dec 08, 2008 at 09:01:11AM +0800, Yan Zheng
wrote:
> 2008/12/8 Niraj kumar <niraj17@gmail.com>:
> >
> Please execute ''btrfsctl -a'' before mount.
> 
> Yan Zheng
Ok, understood.

So, are we going to have a "mount.btrfs" to take care of this in
future?

-Niraj
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On Monday 08 December 2008 04:44:01 Niraj Kumar wrote:
> On Mon, Dec 08, 2008 at 09:01:11AM +0800, Yan Zheng wrote:
> > 2008/12/8 Niraj kumar <niraj17@gmail.com>:
> >
> > Please execute ''btrfsctl -a'' before mount.
How does this play nice with root partitions that are planned to be btrfs?

Regards,
Christian.
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On Sun, Jan 4, 2009 at 12:38 PM, Christian Parpart <trapni@gentoo.org>
wrote:
> On Monday 08 December 2008 04:44:01 Niraj Kumar wrote:
>> On Mon, Dec 08, 2008 at 09:01:11AM +0800, Yan Zheng wrote:
>> > 2008/12/8 Niraj kumar <niraj17@gmail.com>:
>> >
>> > Please execute ''btrfsctl -a'' before mount.
>
> How does this play nice with root partitions that are planned to be btrfs?
>
initrd ?

basically is the same problem that root partitions on md
raid0,1,10,5,6 face... device discovery and assembly of block device
in case of md, or assembly of filesystem kernel data/structs in case
of btrfs.

> Regards,
> Christian.
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-- 
Miguel Sousa Filipe
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