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

DISCUSSION Lubos Kolouch 4 participants 11 messages Feb 8, 2011 – Feb 10, 2011 Btrfs file system

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Lubos Kolouch

author

2011-02-08 06:57 UTC #0 lore raw

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

Goffredo Baroncelli

2011-02-08 20:00 UTC #1 lore raw

Quoted 5 lines · Lubos Kolouch

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

Quoted 8 lines

# 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

Quoted 4 lines

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]

Quoted 6 lines

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Lubos Kolouch

author

2011-02-08 21:26 UTC #2 lore raw

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

Quoted 11 lines · Lubos Kolouch

Quoted 10 lines
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

Quoted 9 lines

Quoted 3 lines
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

Goffredo Baroncelli

2011-02-09 18:25 UTC #3 lore raw

Quoted 23 lines · Lubos Kolouch

Goffredo Baroncelli, Tue, 08 Feb 2011 21:00:25 +0100:
Quoted 11 lines · Lubos Kolouch
Quoted 10 lines
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
Quoted 9 lines
Quoted 3 lines
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 ?

Quoted 5 lines

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.

Quoted 6 lines

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Lubos Kolouch

author

2011-02-09 20:12 UTC #4 lore raw

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

Quoted 27 lines · Lubos Kolouch

Quoted 26 lines
Goffredo Baroncelli, Tue, 08 Feb 2011 21:00:25 +0100:
Quoted 11 lines · Lubos Kolouch
Quoted 10 lines
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
Quoted 10 lines
Quoted 3 lines
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

Quoted 8 lines

Quoted 3 lines
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

Chris Samuel

2011-02-10 03:09 UTC #5 lore raw

Quoted 1 line · Lubos Kolouch

/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

Signature · 1 line

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

Lubos Kolouch

author

2011-02-10 06:54 UTC #6 lore raw

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

Quoted 11 lines · Lubos Kolouch

Quoted 2 lines
/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

Helmut Hullen

2011-02-10 07:47 UTC #8 lore raw

In reply to Lubos Kolouch

Hallo, Lubos,

Du meintest am 09.02.11:

Quoted 4 lines

# 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

Helmut Hullen

2011-02-10 07:49 UTC #7 lore raw

In reply to Lubos Kolouch

Hallo, Lubos,

Du meintest am 10.02.11:

Quoted 5 lines

Quoted 1 line
Quoted 1 line
/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

Goffredo Baroncelli

2011-02-10 18:24 UTC #9 lore raw

In reply to Lubos Kolouch

Quoted 77 lines · Lubos Kolouch

Goffredo Baroncelli, Wed, 09 Feb 2011 19:25:34 +0100:
Quoted 27 lines · Lubos Kolouch
Quoted 26 lines
Goffredo Baroncelli, Tue, 08 Feb 2011 21:00:25 +0100:
Quoted 11 lines · Lubos Kolouch
Quoted 10 lines
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
Quoted 10 lines
Quoted 3 lines
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
Quoted 8 lines
Quoted 3 lines
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

Quoted 8 lines

# 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.

Quoted 8 lines

Lubos
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.

Lubos Kolouch

author

2011-02-10 18:35 UTC #10 lore raw

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

Quoted 107 lines · Lubos Kolouch

Quoted 75 lines
Goffredo Baroncelli, Wed, 09 Feb 2011 19:25:34 +0100:
Quoted 27 lines · Lubos Kolouch
Quoted 26 lines
Goffredo Baroncelli, Tue, 08 Feb 2011 21:00:25 +0100:
Quoted 11 lines · Lubos Kolouch
Quoted 10 lines
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
Quoted 10 lines
Quoted 3 lines
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
Quoted 8 lines
Quoted 3 lines
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
Quoted 8 lines
# 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.

Quoted 5 lines

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