mkfs.btrfs - error checking /dev/sda5 mount status

mkfs.btrfs - error checking /dev/sda5 mount status

[Lubos Kolouch]

Hi,

I'm hitting this issue - sda5 is a normal device, nothing to do with 
loop, encryption etc.

# mkfs.btrfs /dev/sda5

WARNING! - Btrfs v0.19-35-g1b444cd-dirty IS EXPERIMENTAL
WARNING! - see http://btrfs.wiki.kernel.org before using

error checking /dev/sda5 mount status

Is there something I can do to resolve this?

Thank you

Lubos

Re: mkfs.btrfs - error checking /dev/sda5 mount status

[Goffredo Baroncelli]

On 02/08/2011 07:57 AM, Lubos Kolouch wrote:
> Hi,
> 
> I'm hitting this issue - sda5 is a normal device, nothing to do with 
> loop, encryption etc.
> 
> # mkfs.btrfs /dev/sda5
> 
> WARNING! - Btrfs v0.19-35-g1b444cd-dirty IS EXPERIMENTAL
> WARNING! - see http://btrfs.wiki.kernel.org before using
> 
> error checking /dev/sda5 mount status
> 
> Is there something I can do to resolve this?

Some months ago I posted a patch [*] which allows to create a filesystem
even if an integrity tests fail.
Anyway it would be interesting understand why mkfs.btrfs fails. It is
possible to have a strace of the command ?

Regards
G.Baroncelli


> Thank you
> 
> Lubos
> 

[*] email dated 01/03/2011 - subject: [PATCH] add a --force option to
mkfs.btrf [was Re: Odd mkbtrfs behavior inside of chroot]

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> 

Re: mkfs.btrfs - error checking /dev/sda5 mount status

[Lubos Kolouch]

Goffredo Baroncelli, Tue, 08 Feb 2011 21:00:25 +0100:

> On 02/08/2011 07:57 AM, Lubos Kolouch wrote:
>> Hi,
>> 
>> I'm hitting this issue - sda5 is a normal device, nothing to do with
>> loop, encryption etc.
>> 
>> # mkfs.btrfs /dev/sda5
>> 
>> WARNING! - Btrfs v0.19-35-g1b444cd-dirty IS EXPERIMENTAL WARNING! - see
>> http://btrfs.wiki.kernel.org before using
>> 
>> error checking /dev/sda5 mount status
>> 
>> Is there something I can do to resolve this?
> 
> Some months ago I posted a patch [*] which allows to create a filesystem
> even if an integrity tests fail.
> Anyway it would be interesting understand why mkfs.btrfs fails. It is
> possible to have a strace of the command ?
> 

here ... http://paste.pocoo.org/show/334638/
but it is not in chroot, it is in "normal" system

Lubos

Re: mkfs.btrfs - error checking /dev/sda5 mount status

[Goffredo Baroncelli]

On 02/08/2011 10:26 PM, Lubos Kolouch wrote:
> Goffredo Baroncelli, Tue, 08 Feb 2011 21:00:25 +0100:
> 
>> On 02/08/2011 07:57 AM, Lubos Kolouch wrote:
>>> Hi,
>>>
>>> I'm hitting this issue - sda5 is a normal device, nothing to do with
>>> loop, encryption etc.
>>>
>>> # mkfs.btrfs /dev/sda5
>>>
>>> WARNING! - Btrfs v0.19-35-g1b444cd-dirty IS EXPERIMENTAL WARNING! - see
>>> http://btrfs.wiki.kernel.org before using
>>>
>>> error checking /dev/sda5 mount status
>>>
>>> Is there something I can do to resolve this?
>>
>> Some months ago I posted a patch [*] which allows to create a filesystem
>> even if an integrity tests fail.
>> Anyway it would be interesting understand why mkfs.btrfs fails. It is
>> possible to have a strace of the command ?
>>
> 
> here ... http://paste.pocoo.org/show/334638/
> but it is not in chroot, it is in "normal" system
> 
> Lubos
> 

Hi Lubos,

Could you post also the output of "cat /proc/mounts" command and the
output of "btrfs filesystem show" command.
I cannot understand what should be the problem.


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Re: mkfs.btrfs - error checking /dev/sda5 mount status

[Lubos Kolouch]

Goffredo Baroncelli, Wed, 09 Feb 2011 19:25:34 +0100:

> On 02/08/2011 10:26 PM, Lubos Kolouch wrote:
>> Goffredo Baroncelli, Tue, 08 Feb 2011 21:00:25 +0100:
>> 
>>> On 02/08/2011 07:57 AM, Lubos Kolouch wrote:
>>>> Hi,
>>>>
>>>> I'm hitting this issue - sda5 is a normal device, nothing to do with
>>>> loop, encryption etc.
>>>>
>>>> # mkfs.btrfs /dev/sda5
>>>>
>>>> WARNING! - Btrfs v0.19-35-g1b444cd-dirty IS EXPERIMENTAL WARNING! -
>>>> see http://btrfs.wiki.kernel.org before using
>>>>
>>>> error checking /dev/sda5 mount status
>>>>
>>>> Is there something I can do to resolve this?
>>>
>>> Some months ago I posted a patch [*] which allows to create a
>>> filesystem even if an integrity tests fail.
>>> Anyway it would be interesting understand why mkfs.btrfs fails. It is
>>> possible to have a strace of the command ?
>>>
>>>
>> here ... http://paste.pocoo.org/show/334638/ but it is not in chroot,
>> it is in "normal" system
>> 
>> Lubos
>> 
>> 
> Hi Lubos,
> 
> Could you post also the output of "cat /proc/mounts" command and the
> output of "btrfs filesystem show" command. I cannot understand what
> should be the problem.

Hi Goffredo,

Sure,
# cat /proc/mounts

rootfs / rootfs rw 0 0
/dev/root / btrfs rw,noatime,compress,ssd 0 0
proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0
rc-svcdir /lib/rc/init.d tmpfs 
rw,nosuid,nodev,noexec,relatime,size=1024k,mode=755 0 0
sysfs /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
securityfs /sys/kernel/security securityfs rw,nosuid,nodev,noexec,relatime 
0 0
debugfs /sys/kernel/debug debugfs rw,nosuid,nodev,noexec,relatime 0 0
udev /dev devtmpfs 
rw,nosuid,relatime,size=10240k,nr_inodes=217934,mode=755 0 0
fusectl /sys/fs/fuse/connections fusectl rw,relatime 0 0
none /dev/pts devpts rw,relatime,mode=600,ptmxmode=000 0 0
none /dev/shm tmpfs rw,relatime 0 0
/dev/sda1 /boot ext2 rw,relatime,errors=continue 0 0
none /var/tmp/portage tmpfs rw,relatime 0 0
binfmt_misc /proc/sys/fs/binfmt_misc binfmt_misc 
rw,nosuid,nodev,noexec,relatime 0 0
/dev/mapper/_dev_sda6 /home btrfs rw,noatime,compress,ssd 0 0

# btrfs filesystem show

Label: none  uuid: fd070c17-e98b-4b50-9fa8-3453482aafa2
	Total devices 1 FS bytes used 5.51GB
	devid    1 size 18.64GB used 10.79GB path /dev/sda2

Label: none  uuid: bf9a1b00-f8bd-44d3-b140-10eea088a60e
	Total devices 1 FS bytes used 6.73GB
	devid    1 size 19.54GB used 19.54GB path /dev/sda5

Label: none  uuid: ae0ba016-1945-4e7a-9fb4-e9311d199727
	Total devices 1 FS bytes used 57.50GB
	devid    1 size 78.91GB used 78.91GB path /dev/dm-0

# mkfs.btrfs /dev/sda5

WARNING! - Btrfs v0.19-35-g1b444cd-dirty IS EXPERIMENTAL
WARNING! - see http://btrfs.wiki.kernel.org before using

error checking /dev/sda5 mount status

Also, I can mount it no problem - strange, isn't it

Lubos

Re: mkfs.btrfs - error checking /dev/sda5 mount status

[Chris Samuel]

On 10/02/11 07:12, Lubos Kolouch wrote:

> /dev/root / btrfs rw,noatime,compress,ssd 0 0

My memory of the strace showed that there was no /dev/root
when it tried to open it - can you confirm whether or not
that's the case please ?

cheers!
Chris
-- 
 Chris Samuel  :  http://www.csamuel.org/  :  Melbourne, VIC

Re: mkfs.btrfs - error checking /dev/sda5 mount status

[Lubos Kolouch]

Chris Samuel, Thu, 10 Feb 2011 14:09:17 +1100:

> On 10/02/11 07:12, Lubos Kolouch wrote:
> 
>> /dev/root / btrfs rw,noatime,compress,ssd 0 0
> 
> My memory of the strace showed that there was no /dev/root when it tried
> to open it - can you confirm whether or not that's the case please ?
> 
> cheers!
> Chris
> --
>  Chris Samuel  :  http://www.csamuel.org/  :  Melbourne, VIC

Chris, 

You mean this?

# ls -la /dev/root 
ls: cannot access /dev/root: No such file or directory

Lubos

Re: mkfs.btrfs - error checking /dev/sda5 mount status

[Helmut Hullen]

Hallo, Lubos,

Du meintest am 09.02.11:

> # cat /proc/mounts

> rootfs / rootfs rw 0 0
> /dev/root / btrfs rw,noatime,compress,ssd 0 0

"/dev/root" is a symlink (which I don't like).

        rdev

shows which real device is meant.

Viele Gruesse!
Helmut

Re: mkfs.btrfs - error checking /dev/sda5 mount status

[Helmut Hullen]

Hallo, Lubos,

Du meintest am 10.02.11:

>>> /dev/root / btrfs rw,noatime,compress,ssd 0 0


> # ls -la /dev/root
> ls: cannot access /dev/root: No such file or directory

        ls -la $(rdev)

(but that's no simple way ...)

Viele Gruesse!
Helmut

Re: mkfs.btrfs - error checking /dev/sda5 mount status

[Goffredo Baroncelli]

On 02/09/2011 09:12 PM, Lubos Kolouch wrote:
> Goffredo Baroncelli, Wed, 09 Feb 2011 19:25:34 +0100:
> 
>> On 02/08/2011 10:26 PM, Lubos Kolouch wrote:
>>> Goffredo Baroncelli, Tue, 08 Feb 2011 21:00:25 +0100:
>>>
>>>> On 02/08/2011 07:57 AM, Lubos Kolouch wrote:
>>>>> Hi,
>>>>>
>>>>> I'm hitting this issue - sda5 is a normal device, nothing to do with
>>>>> loop, encryption etc.
>>>>>
>>>>> # mkfs.btrfs /dev/sda5
>>>>>
>>>>> WARNING! - Btrfs v0.19-35-g1b444cd-dirty IS EXPERIMENTAL WARNING! -
>>>>> see http://btrfs.wiki.kernel.org before using
>>>>>
>>>>> error checking /dev/sda5 mount status
>>>>>
>>>>> Is there something I can do to resolve this?
>>>>
>>>> Some months ago I posted a patch [*] which allows to create a
>>>> filesystem even if an integrity tests fail.
>>>> Anyway it would be interesting understand why mkfs.btrfs fails. It is
>>>> possible to have a strace of the command ?
>>>>
>>>>
>>> here ... http://paste.pocoo.org/show/334638/ but it is not in chroot,
>>> it is in "normal" system
>>>
>>> Lubos
>>>
>>>
>> Hi Lubos,
>>
>> Could you post also the output of "cat /proc/mounts" command and the
>> output of "btrfs filesystem show" command. I cannot understand what
>> should be the problem.
> 
> Hi Goffredo,
> 
> Sure,
> # cat /proc/mounts
> 
> rootfs / rootfs rw 0 0
> /dev/root / btrfs rw,noatime,compress,ssd 0 0
> proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0
> rc-svcdir /lib/rc/init.d tmpfs 
> rw,nosuid,nodev,noexec,relatime,size=1024k,mode=755 0 0
> sysfs /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
> securityfs /sys/kernel/security securityfs rw,nosuid,nodev,noexec,relatime 
> 0 0
> debugfs /sys/kernel/debug debugfs rw,nosuid,nodev,noexec,relatime 0 0
> udev /dev devtmpfs 
> rw,nosuid,relatime,size=10240k,nr_inodes=217934,mode=755 0 0
> fusectl /sys/fs/fuse/connections fusectl rw,relatime 0 0
> none /dev/pts devpts rw,relatime,mode=600,ptmxmode=000 0 0
> none /dev/shm tmpfs rw,relatime 0 0
> /dev/sda1 /boot ext2 rw,relatime,errors=continue 0 0
> none /var/tmp/portage tmpfs rw,relatime 0 0
> binfmt_misc /proc/sys/fs/binfmt_misc binfmt_misc 
> rw,nosuid,nodev,noexec,relatime 0 0
> /dev/mapper/_dev_sda6 /home btrfs rw,noatime,compress,ssd 0 0
> 
> # btrfs filesystem show
> 
> Label: none  uuid: fd070c17-e98b-4b50-9fa8-3453482aafa2
> 	Total devices 1 FS bytes used 5.51GB
> 	devid    1 size 18.64GB used 10.79GB path /dev/sda2
> 
> Label: none  uuid: bf9a1b00-f8bd-44d3-b140-10eea088a60e
> 	Total devices 1 FS bytes used 6.73GB
> 	devid    1 size 19.54GB used 19.54GB path /dev/sda5
> 
> Label: none  uuid: ae0ba016-1945-4e7a-9fb4-e9311d199727
> 	Total devices 1 FS bytes used 57.50GB
> 	devid    1 size 78.91GB used 78.91GB path /dev/dm-0
> 
> # mkfs.btrfs /dev/sda5
> 
> WARNING! - Btrfs v0.19-35-g1b444cd-dirty IS EXPERIMENTAL
> WARNING! - see http://btrfs.wiki.kernel.org before using
> 
> error checking /dev/sda5 mount status
> 
> Also, I can mount it no problem - strange, isn't it


Ok, I think to have track down the problem. To me it seems a bug in
mkfs.btrfs.

The first thing that should be highlighted is that you are trying to
format an already btrfs formatted device. In this there is not anything
wrong.

However, before formatting a device mkfs.btrfs performs some sanity
check. It checks if the device is already mounted, scanning /proc/mounts.

In a normal case (the device which will be formatted doesn't contain a
btrfs filesystem), mkfs.btrfs is smart enough to don't check device
which are in /proc/mounts bat doesn't exist (like /dev/root).

Instead when the device which will be formatted already contains a btrfs
filesystem, mkfs.btrfs performs a different checks. In fact it considers
also the case of a multi-device based btrfs filesystem. However in this
case it doesn't skip a not existent device but it raises an error. I
think that this is a bug.

As workaround I suggest the following: make a link between the real root
device and /dev/root.

It should be sufficient to format the device.



> Lubos
> 
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Re: mkfs.btrfs - error checking /dev/sda5 mount status

[Lubos Kolouch]

Goffredo Baroncelli, Thu, 10 Feb 2011 19:24:57 +0100:

> On 02/09/2011 09:12 PM, Lubos Kolouch wrote:
>> Goffredo Baroncelli, Wed, 09 Feb 2011 19:25:34 +0100:
>> 
>>> On 02/08/2011 10:26 PM, Lubos Kolouch wrote:
>>>> Goffredo Baroncelli, Tue, 08 Feb 2011 21:00:25 +0100:
>>>>
>>>>> On 02/08/2011 07:57 AM, Lubos Kolouch wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I'm hitting this issue - sda5 is a normal device, nothing to do
>>>>>> with loop, encryption etc.
>>>>>>
>>>>>> # mkfs.btrfs /dev/sda5
>>>>>>
>>>>>> WARNING! - Btrfs v0.19-35-g1b444cd-dirty IS EXPERIMENTAL WARNING! -
>>>>>> see http://btrfs.wiki.kernel.org before using
>>>>>>
>>>>>> error checking /dev/sda5 mount status
>>>>>>
>>>>>> Is there something I can do to resolve this?
>>>>>
>>>>> Some months ago I posted a patch [*] which allows to create a
>>>>> filesystem even if an integrity tests fail. Anyway it would be
>>>>> interesting understand why mkfs.btrfs fails. It is possible to have
>>>>> a strace of the command ?
>>>>>
>>>>>
>>>> here ... http://paste.pocoo.org/show/334638/ but it is not in chroot,
>>>> it is in "normal" system
>>>>
>>>> Lubos
>>>>
>>>>
>>> Hi Lubos,
>>>
>>> Could you post also the output of "cat /proc/mounts" command and the
>>> output of "btrfs filesystem show" command. I cannot understand what
>>> should be the problem.
>> 
>> Hi Goffredo,
>> 
>> Sure,
>> # cat /proc/mounts
>> 
>> rootfs / rootfs rw 0 0
>> /dev/root / btrfs rw,noatime,compress,ssd 0 0 proc /proc proc
>> rw,nosuid,nodev,noexec,relatime 0 0 rc-svcdir /lib/rc/init.d tmpfs
>> rw,nosuid,nodev,noexec,relatime,size=1024k,mode=755 0 0 sysfs /sys
>> sysfs rw,nosuid,nodev,noexec,relatime 0 0 securityfs
>> /sys/kernel/security securityfs rw,nosuid,nodev,noexec,relatime 0 0
>> debugfs /sys/kernel/debug debugfs rw,nosuid,nodev,noexec,relatime 0 0
>> udev /dev devtmpfs
>> rw,nosuid,relatime,size=10240k,nr_inodes=217934,mode=755 0 0 fusectl
>> /sys/fs/fuse/connections fusectl rw,relatime 0 0 none /dev/pts devpts
>> rw,relatime,mode=600,ptmxmode=000 0 0 none /dev/shm tmpfs rw,relatime 0
>> 0
>> /dev/sda1 /boot ext2 rw,relatime,errors=continue 0 0 none
>> /var/tmp/portage tmpfs rw,relatime 0 0 binfmt_misc
>> /proc/sys/fs/binfmt_misc binfmt_misc rw,nosuid,nodev,noexec,relatime 0
>> 0
>> /dev/mapper/_dev_sda6 /home btrfs rw,noatime,compress,ssd 0 0
>> 
>> # btrfs filesystem show
>> 
>> Label: none  uuid: fd070c17-e98b-4b50-9fa8-3453482aafa2
>> 	Total devices 1 FS bytes used 5.51GB
>> 	devid    1 size 18.64GB used 10.79GB path /dev/sda2
>> 
>> Label: none  uuid: bf9a1b00-f8bd-44d3-b140-10eea088a60e
>> 	Total devices 1 FS bytes used 6.73GB
>> 	devid    1 size 19.54GB used 19.54GB path /dev/sda5
>> 
>> Label: none  uuid: ae0ba016-1945-4e7a-9fb4-e9311d199727
>> 	Total devices 1 FS bytes used 57.50GB devid    1 size 78.91GB used
>> 	78.91GB path /dev/dm-0
>> 
>> # mkfs.btrfs /dev/sda5
>> 
>> WARNING! - Btrfs v0.19-35-g1b444cd-dirty IS EXPERIMENTAL WARNING! - see
>> http://btrfs.wiki.kernel.org before using
>> 
>> error checking /dev/sda5 mount status
>> 
>> Also, I can mount it no problem - strange, isn't it
> 
> 
> Ok, I think to have track down the problem. To me it seems a bug in
> mkfs.btrfs.
> 
> The first thing that should be highlighted is that you are trying to
> format an already btrfs formatted device. In this there is not anything
> wrong.
> 
> However, before formatting a device mkfs.btrfs performs some sanity
> check. It checks if the device is already mounted, scanning
> /proc/mounts.
> 
> In a normal case (the device which will be formatted doesn't contain a
> btrfs filesystem), mkfs.btrfs is smart enough to don't check device
> which are in /proc/mounts bat doesn't exist (like /dev/root).
> 
> Instead when the device which will be formatted already contains a btrfs
> filesystem, mkfs.btrfs performs a different checks. In fact it considers
> also the case of a multi-device based btrfs filesystem. However in this
> case it doesn't skip a not existent device but it raises an error. I
> think that this is a bug.
> 
> As workaround I suggest the following: make a link between the real root
> device and /dev/root.
> 
> It should be sufficient to format the device.
> 

Hello - you are right...

# ln -s /dev/sda2 /dev/root

# mkfs.btrfs /dev/sda5

WARNING! - Btrfs v0.19-35-g1b444cd-dirty IS EXPERIMENTAL
WARNING! - see http://btrfs.wiki.kernel.org before using

fs created label (null) on /dev/sda5
	nodesize 4096 leafsize 4096 sectorsize 4096 size 19.54GB
Btrfs v0.19-35-g1b444cd-dirty


Lubos