Re: [PATCH] Btrfs-progs: add feature to get mininum size for resizing a fs/device

[Filipe Manana <fdmanana@kernel.org>]

On Tue, Jun 30, 2015 at 4:14 PM, David Sterba <dsterba@suse.cz> wrote:
> On Mon, Jun 29, 2015 at 05:15:12PM +0100, Filipe Manana wrote:
>> On Mon, Jun 29, 2015 at 4:42 PM, David Sterba <dsterba@suse.cz> wrote:
>> > On Wed, Jun 17, 2015 at 12:44:55PM +0100, fdmanana@kernel.org wrote:
>> > The test fails after I do this before unmount:
>> >
>> > $SUDO_HELPER $TOP/btrfs balance start -mconvert=single -sconvert=single -f $TEST_MNT
>> > shrink_test
>>
>> Where are you doing this exactly?
>>
>> Just tried the following:  https://friendpaste.com/2U7C4gBBLBjo4e2v1ZnJP2
>
> Like in the the first part of the diff.
>
>> > Output:
>> >
>> > ############### root_helper ../btrfs filesystem resize get_min_size ../tests/mnt
>> > 6480199680 bytes (6.04GiB)
>> > min size = 6480199680
>> > ############### root_helper ../btrfs filesystem resize 6480199680 ../tests/mnt
>> > ERROR: unable to resize '../tests/mnt' - No space left on device
>> > Resize '../tests/mnt' of '6480199680'
>> >
>> > Last successful resize before this was:
>> > Resize '../tests/mnt' of '7553941504'
>>
>> And it didn't fail for me on a 4.1 kernel at least. It produced those
>> 2 sizes as well, but it didn't fail for any of them.
>
> The test was run on 4.0.5, I'm building a clean 4.1 + integration to
> verify it there.

Nevermind, I managed to reproduce it but by placing the
balance/convert before the loop that tests the shrinking.
btrfs_can_relocate() returns 0, meaning relocation should succeed if
no other allocations happen in parallel, which is the case here, but
btrfs_relocate_block_group() fails with ENOSPC - one of this functions
isn't working as it should, I'll check what's going on soon.

thanks