btrfs qgroup destroy -> ERROR: unable to create quota group: Device or resource busy

DISCUSSION Tomasz Chmielewski 3 participants 8 messages Aug 9, 2013 Btrfs file system

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Tomasz Chmielewski

author

2013-08-09 05:39 UTC #0 lore raw

I'm using qgroups and have created a few hundreds of subvolumes in the past.

It seems that btrfs automatically assigns a qgroup to newly created snapshot/subvolume, but does not destroy the qgroup when the subvolume is deleted.

So I've tried to destroy the unused qgroups, with mixed success. I was able to destroy most of them, but some are still failing, i.e.:

# btrfs qgroup destroy 4494 /mnt/lxc1
ERROR: unable to create quota group: Device or resource busy

Note the negative number here, but I also have qgroups with both positive numbers, which I'm not able to destroy as well:

# btrfs qgroup show /mnt/lxc1 | grep 4494
0/4494 839516160 -69632

qgroup 4494 is not used by any subvolume:

# btrfs sub list /mnt/lxc1 | grep 4494

I did run "btrfs quota rescan" for this filesystem, hoping it will fix the problem, but it didn't.

Any advice?

Signature · 2 lines

Tomasz Chmielewski
http://wpkg.org

Wang Shilong

2013-08-09 05:57 UTC #1 lore raw

Hello,

Quoted 6 lines · Tomasz Chmielewski

I'm using qgroups and have created a few hundreds of subvolumes in the past.
It seems that btrfs automatically assigns a qgroup to newly created snapshot/subvolume, but does not destroy the qgroup when the subvolume is deleted.

This should be implemented. And will soon.

Quoted 6 lines

So I've tried to destroy the unused qgroups, with mixed success. I was able to destroy most of them, but some are still failing, i.e.:
# btrfs qgroup destroy 4494 /mnt/lxc1
ERROR: unable to create quota group: Device or resource busy

Just remove qgroup（4494）'s parent qgroup. then it can be removed. Anyway, i think this is unnecessary.

Thanks,
Wang

Quoted 21 lines

Note the negative number here, but I also have qgroups with both positive numbers, which I'm not able to destroy as well:
# btrfs qgroup show /mnt/lxc1 | grep 4494
0/4494 839516160 -69632
qgroup 4494 is not used by any subvolume:
# btrfs sub list /mnt/lxc1 | grep 4494
I did run "btrfs quota rescan" for this filesystem, hoping it will fix the problem, but it didn't.
Any advice?

Tomasz Chmielewski

author

2013-08-09 06:07 UTC #2 lore raw

Quoted 5 lines · On Fri, 09 Aug 2013 13:56:19 +0800 Wang Shilong <[email protected]>…

Quoted 3 lines
It seems that btrfs automatically assigns a qgroup to newly created snapshot/subvolume, but does not destroy the qgroup when the subvolume is deleted.
This should be implemented. And will soon.

Great to hear (using 3.11-rc4 now).

Quoted 8 lines

Quoted 5 lines
So I've tried to destroy the unused qgroups, with mixed success. I was able to destroy most of them, but some are still failing, i.e.:
# btrfs qgroup destroy 4494 /mnt/lxc1
ERROR: unable to create quota group: Device or resource busy
Just remove qgroup（4494）'s parent qgroup. then it can be removed. Anyway, i think this is unnecessary.

I don't want to remove the parent qgroup, as it's in use by other subvolumes:

# /usr/src/qgroup/btrfs-progs/btrfs qgroup show -c /mnt/lxc1 | grep 4494

0/4494 839516160 18446744073709481984 --- <------ want to remove only this one

13/1 2142674944 2142674944 0/3973,0/3974,0/3978,0/3981,0/4355,0/4373,0/4398,0/4400,0/4401,0/4427,0/4448,0/4449,0/4457,0/4458,0/4475,0/4476,0/4487,0/4488,0/4489,0/4490,0/4491,0/4492,0/4493,0/4494,0/4495,0/4496,0/4497,0/4498,0/4499,0/4506,0/4507,0/4518

Parent qgroup 13/1 makes accounting for other qgroups - therefore, I don't want to remove it.

BTW, "/usr/src/qgroup/btrfs-progs/btrfs" is from http://github.com/miaoxie/btrfs-progs.git, to support printing parent/child qgroup IDs.

Note it shows different values than btrfs from official repository - is that expected?

# /usr/src/qgroup/btrfs-progs/btrfs qgroup show /mnt/lxc1 | grep 4494
0/4494 839516160 18446744073709481984

# btrfs qgroup show /mnt/lxc1 | grep 4494
0/4494 839516160 -69632

Signature · 2 lines

Tomasz Chmielewski
http://wpkg.org

Wang Shilong

2013-08-09 06:10 UTC #3 lore raw

Quoted 23 lines · Tomasz Chmielewski

Quoted 5 lines · On Fri, 09 Aug 2013 13:56:19 +0800 Wang Shilong <[email protected]>…
Quoted 3 lines
It seems that btrfs automatically assigns a qgroup to newly created snapshot/subvolume, but does not destroy the qgroup when the subvolume is deleted.
This should be implemented. And will soon.
Great to hear (using 3.11-rc4 now).
Quoted 8 lines
Quoted 5 lines
So I've tried to destroy the unused qgroups, with mixed success. I was able to destroy most of them, but some are still failing, i.e.:
# btrfs qgroup destroy 4494 /mnt/lxc1
ERROR: unable to create quota group: Device or resource busy
Just remove qgroup（4494）'s parent qgroup. then it can be removed. Anyway, i think this is unnecessary.
I don't want to remove the parent qgroup, as it's in use by other subvolumes:

Quoted 8 lines

# /usr/src/qgroup/btrfs-progs/btrfs qgroup show -c /mnt/lxc1 | grep 4494
0/4494 839516160 18446744073709481984 --- <------ want to remove only this one
13/1 2142674944 2142674944 0/3973,0/3974,0/3978,0/3981,0/4355,0/4373,0/4398,0/4400,0/4401,0/4427,0/4448,0/4449,0/4457,0/4458,0/4475,0/4476,0/4487,0/4488,0/4489,0/4490,0/4491,0/4492,0/4493,0/4494,0/4495,0/4496,0/4497,0/4498,0/4499,0/4506,0/4507,0/4518
Parent qgroup 13/1 makes accounting for other qgroups - therefore, I don't want to remove it.

Sorry, you must destroy relation between 13/1 and 4494. then you can remove it.

thanks,
Wang

Quoted 13 lines

BTW, "/usr/src/qgroup/btrfs-progs/btrfs" is from http://github.com/miaoxie/btrfs-progs.git, to support printing parent/child qgroup IDs.
Note it shows different values than btrfs from official repository - is that expected?
# /usr/src/qgroup/btrfs-progs/btrfs qgroup show /mnt/lxc1 | grep 4494
0/4494 839516160 18446744073709481984
# btrfs qgroup show /mnt/lxc1 | grep 4494
0/4494 839516160 -69632

Tomasz Chmielewski

author

2013-08-09 06:42 UTC #4 lore raw

Quoted 7 lines · On Fri, 09 Aug 2013 14:08:48 +0800 Wang Shilong <[email protected]>…

Quoted 7 lines
0/4494 839516160 18446744073709481984 --- <------ want to remove
only this one
13/1 2142674944 2142674944 0/3973,0/3974,0/3978,0/3981,0/4355,0/4373,0/4398,0/4400,0/4401,0/4427,0/4448,0/4449,0/4457,0/4458,0/4475,0/4476,0/4487,0/4488,0/4489,0/4490,0/4491,0/4492,0/4493,0/4494,0/4495,0/4496,0/4497,0/4498,0/4499,0/4506,0/4507,0/4518

Quoted 5 lines

Quoted 2 lines
Parent qgroup 13/1 makes accounting for other qgroups - therefore, I don't want to remove it.
Sorry, you must destroy relation between 13/1 and 4494. then you can remove it.

So how exactly should I do it? A bit confused on how to proceed.

- remove 13/1, remove 4494

- add 13/1, and add all previous qgroups to it? 0/3973,0/3974,0/3978,0/3981,0/4355,0/4373,0/4398,0/4400,0/4401,....

- run quota scan?

It can't be right, can it?

Signature · 2 lines

Tomasz Chmielewski
http://wpkg.org

Wang Shilong

2013-08-09 06:57 UTC #5 lore raw

Quoted 10 lines · Tomasz Chmielewski

Quoted 7 lines · On Fri, 09 Aug 2013 14:08:48 +0800 Wang Shilong <[email protected]>…
Quoted 7 lines
0/4494 839516160 18446744073709481984 --- <------ want to remove
only this one
13/1 2142674944 2142674944 0/3973,0/3974,0/3978,0/3981,0/4355,0/4373,0/4398,0/4400,0/4401,0/4427,0/4448,0/4449,0/4457,0/4458,0/4475,0/4476,0/4487,0/4488,0/4489,0/4490,0/4491,0/4492,0/4493,0/4494,0/4495,0/4496,0/4497,0/4498,0/4499,0/4506,0/4507,0/4518

Quoted 7 lines

Quoted 5 lines
Quoted 2 lines
Parent qgroup 13/1 makes accounting for other qgroups - therefore, I don't want to remove it.
Sorry, you must destroy relation between 13/1 and 4494. then you can remove it.
So how exactly should I do it? A bit confused on how to proceed.

btrfs qgroup remove 4494 13/1 <mnt>

will destroy relation between 4494 and 13/1
Then you can try:

btrfs qgroup destroy 4494 <mnt>

Thanks,
Wang

Quoted 12 lines

- remove 13/1, remove 4494
- add 13/1, and add all previous qgroups to it? 0/3973,0/3974,0/3978,0/3981,0/4355,0/4373,0/4398,0/4400,0/4401,....
- run quota scan?
It can't be right, can it?

Tomasz Chmielewski

author

2013-08-09 07:47 UTC #6 lore raw

Quoted 8 lines · On Fri, 09 Aug 2013 14:56:15 +0800 Wang Shilong <[email protected]>…

Quoted 1 line
So how exactly should I do it? A bit confused on how to proceed.
btrfs qgroup remove 4494 13/1 <mnt>
will destroy relation between 4494 and 13/1
Then you can try:
btrfs qgroup destroy 4494 <mnt>

Excellent, thanks a lot!

Signature · 2 lines

Tomasz Chmielewski
http://wpkg.org

Wang Shilong

2013-08-09 12:47 UTC #7 lore raw

In reply to Tomasz Chmielewski

Hello, just add my answer for a missing question.

Quoted 34 lines

Quoted 5 lines · On Fri, 09 Aug 2013 13:56:19 +0800 Wang Shilong <[email protected]>…
Quoted 3 lines
It seems that btrfs automatically assigns a qgroup to newly created snapshot/subvolume, but does not destroy the qgroup when the subvolume is deleted.
This should be implemented. And will soon.
Great to hear (using 3.11-rc4 now).
Quoted 8 lines
Quoted 5 lines
So I've tried to destroy the unused qgroups, with mixed success. I was able to destroy most of them, but some are still failing, i.e.:
# btrfs qgroup destroy 4494 /mnt/lxc1
ERROR: unable to create quota group: Device or resource busy
Just remove qgroup（4494）'s parent qgroup. then it can be removed. Anyway, i think this is unnecessary.
I don't want to remove the parent qgroup, as it's in use by other subvolumes:
# /usr/src/qgroup/btrfs-progs/btrfs qgroup show -c /mnt/lxc1 | grep 4494
0/4494 839516160 18446744073709481984 --- <------ want to remove only this one
13/1 2142674944 2142674944 0/3973,0/3974,0/3978,0/3981,0/4355,0/4373,0/4398,0/4400,0/4401,0/4427,0/4448,0/4449,0/4457,0/4458,0/4475,0/4476,0/4487,0/4488,0/4489,0/4490,0/4491,0/4492,0/4493,0/4494,0/4495,0/4496,0/4497,0/4498,0/4499,0/4506,0/4507,0/4518
Parent qgroup 13/1 makes accounting for other qgroups - therefore, I don't want to remove it.

Quoted 6 lines

BTW, "/usr/src/qgroup/btrfs-progs/btrfs" is from http://github.com/miaoxie/btrfs-progs.git, to support printing parent/child qgroup IDs.
Note it shows different values than btrfs from official repository - is that expected?
# /usr/src/qgroup/btrfs-progs/btrfs qgroup show /mnt/lxc1 | grep 4494
0/4494 839516160 18446744073709481984

In fact, group's exclusive must be less or equal than it's referenced value, if you find it is not true in official progs, you can report it!

Here should be expected, because, i don't cast qgroup's value to s64 while it is stored as u64. I will fix this problem when i rebase my patch-set.

In fact, i doubt whether qgroup's exclusive helps, because it always can not work very well, it requires user to track the value especially snapshoting.

Thanks,
Wang

Quoted 11 lines

# btrfs qgroup show /mnt/lxc1 | grep 4494
0/4494 839516160 -69632

Signature · 6 lines

Tomasz Chmielewski
http://wpkg.org
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