btrfs listing is wrong

btrfs listing is wrong

[Mark Murawski]

Label: 'Root'  uuid: d71404d4-468e-47d5-8f06-3b65fa7776aa
         Total devices 2 FS bytes used 7.46GiB
         devid    1 size 9.31GiB used 8.06GiB path /dev/sdh6
         devid    3 size 9.31GiB used 8.06GiB path 
/dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa

# ls -al /dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa
lrwxrwxrwx 1 root root 10 Sep 11 10:43 
/dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa -> ../../sdh6

devid 3 should really  be showing /dev/sde6

Re: btrfs listing is wrong

[Duncan]

Mark Murawski posted on Thu, 11 Sep 2014 10:45:58 -0400 as excerpted:

> Label: 'Root'  uuid: d71404d4-468e-47d5-8f06-3b65fa7776aa
>          Total devices 2 FS bytes used 7.46GiB
>          devid    1 size 9.31GiB used 8.06GiB path /dev/sdh6
>          devid    3 size 9.31GiB used 8.06GiB path
> /dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa
> 
> # ls -al /dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa
> lrwxrwxrwx 1 root root 10 Sep 11 10:43
> /dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa -> ../../sdh6
> 
> devid 3 should really  be showing /dev/sde6

I believe that's an instance of a known bug (or depending on how you look 
at it possibly two) with a recently posted patch, but I doubt it has made 
it to mainline just yet.

What they're going to do is resolve to the canonical paths.  They don't 
do that at this point, and the paths can change, sometimes showing the 
wrong one for certain devices.

I'm not sure the fix will make it into this kernel cycle, however.  It 
should make it into 3.18 in any case, and will likely be stable-backported 
after that.

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman

Re: btrfs listing is wrong

[Anand Jain]

Hi Mark,

> Label: 'Root'  uuid: d71404d4-468e-47d5-8f06-3b65fa7776aa
>          Total devices 2 FS bytes used 7.46GiB
>          devid    1 size 9.31GiB used 8.06GiB path /dev/sdh6
>          devid    3 size 9.31GiB used 8.06GiB path
> /dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa

  I hope this taken when Root is mounted, (just for confirmation),
  which means those are read from the btrfs kernel. Not by scanning
  the udev.

> # ls -al /dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa
> lrwxrwxrwx 1 root root 10 Sep 11 10:43
> /dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa -> ../../sdh6


  when we read /dev/sdh6 it was devid 1.
  When we read /dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa it 
was devid 3.

  But udev also says
    /dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa
  is nothing but a soft link to /dev/sdh6 !!

  Very strange !  Can you run blkid and show its output ?

  Also by any chance did we do a disk to disk copy ?

> devid 3 should really  be showing /dev/sde6

  A reboot or btrfs kernel module reload might update the stale
  and tell the facts.


Thanks, Anand

Re: btrfs listing is wrong

[Mark Murawski]

Root is mounted.   This is the same picture after several reboots.


I've actually did some switching things around, drive swaps and some 
expansions but it's still oddly displayed.

Label: 'Root'  uuid: d71404d4-468e-47d5-8f06-3b65fa7776aa
         Total devices 2 FS bytes used 5.81GiB
         devid    3 size 10.00GiB used 6.78GiB path /dev/sdd6
         devid    4 size 10.00GiB used 6.78GiB path 
/dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa

cartman {~} root# ls -al 
/dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa
lrwxrwxrwx 1 root root 10 Sep 16 16:05 
/dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa -> ../../sdd6


cartman {~} root# blkid  /dev/sdd6
/dev/sdd6: LABEL="Root" UUID="d71404d4-468e-47d5-8f06-3b65fa7776aa" 
UUID_SUB="4ab62e9d-e1dc-4cea-92da-b2640fa841d0" TYPE="btrfs"

cartman {~} root# blkid  /dev/sdi6
/dev/sdi6: LABEL="Root" UUID="d71404d4-468e-47d5-8f06-3b65fa7776aa" 
UUID_SUB="bf76e31c-a49c-4497-83fb-5cb6567b5ad3" TYPE="btrfs"

(dev 4 is really /dev/sdi6)

This was originally a natively created btrfs via mkfs



On 09/13/2014 02:27 AM, Anand Jain wrote:
>
>
> Hi Mark,
>
>> Label: 'Root'  uuid: d71404d4-468e-47d5-8f06-3b65fa7776aa
>>          Total devices 2 FS bytes used 7.46GiB
>>          devid    1 size 9.31GiB used 8.06GiB path /dev/sdh6
>>          devid    3 size 9.31GiB used 8.06GiB path
>> /dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa
>
>  I hope this taken when Root is mounted, (just for confirmation),
>  which means those are read from the btrfs kernel. Not by scanning
>  the udev.
>
>> # ls -al /dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa
>> lrwxrwxrwx 1 root root 10 Sep 11 10:43
>> /dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa -> ../../sdh6
>
>
>  when we read /dev/sdh6 it was devid 1.
>  When we read /dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa 
> it was devid 3.
>
>  But udev also says
>    /dev/disk/by-uuid/d71404d4-468e-47d5-8f06-3b65fa7776aa
>  is nothing but a soft link to /dev/sdh6 !!
>
>  Very strange !  Can you run blkid and show its output ?
>
>  Also by any chance did we do a disk to disk copy ?
>
>> devid 3 should really  be showing /dev/sde6
>
>  A reboot or btrfs kernel module reload might update the stale
>  and tell the facts.
>
>
> Thanks, Anand