Re: [PATCH 0/6] btrfs-progs: Support for BG_TREE feature

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

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On 2019/2/26 上午12:36, Hans van Kranenburg wrote:
> Sorry to bother you again...
> 
> On 12/28/18 9:38 AM, Qu Wenruo wrote:
>> This patchset can be fetched from github:
>> https://github.com/adam900710/btrfs-progs/tree/bg_tree
>> The basis commit is:
>>
>> commit 7d16a2b460182ee98c649533a6975b6e419c3d71
>> Author: Qu Wenruo <wqu@suse.com>
>> Date:   Thu Dec 27 13:49:18 2018 +0800
>>
>>     btrfs-progs: Create uuid tree with proper contents
>>
>> Which is further based on devel branch.
>>
>> This patchset provides the needed user space infrastructure for BG_TREE
>> feature.
>>
>> Since it's an new exclusive feature, unlike SKINNY_METADATA, btrfs-progs
>> is needed to convert existing fs (unmounted) to new format.
>>
>> Although I have prepared the functionality, convert_to_bg_tree(), and
>> already uses it in mkfs, I haven't decided if I should put it under
>> btrfstune, as btrfstune isn't such offline convert tool.
> 
> Ok, so, the convert_to_bg_tree still needs wiring up somewhere before
> it's possible to convert an existing fs?

Sorry, I haven't investigate more time for this convert.
It's more or less expected to be something use it or not so far.

> 
> I want to test with a (iSCSI level clone of a) rather large-ish
> filesystem, so I was searching for how to convert that in place.
> 
> Do you have an idea for a (quick hack?) way to make this happen?

Btrfs-progs needs extra patch for it, but I haven't implemented it yet.
It shouldn't be super complex, but I'm not confident enough yet.

If nothing goes wrong, I'll update the btrfs-progs patchset this week
with (maybe PoC) offline convert.

Thanks,
Qu
> 
> Doing the offline conversion itself is also already an interesting
> thing, seeing how it behaves with some tens of thousands of block
> groups... (As the intended audience for it will mostly be people having
> large filesystems already.)
> 
>> If anyone has better idea on the new convert tool interface, I'm all
>> ears.
>>
>> For the performance improvement, please check the kernel patchset cover
>> letter or the last patch.
>> (SPOILER ALERT: It's super fast)
>>
>> Qu Wenruo (6):
>>   btrfs-progs: Refactor excluded extent functions to use fs_info
>>   btrfs-progs: Refactor btrfs_read_block_groups()
>>   btrfs-progs: Enable read-write ability for 'bg_tree' feature
>>   btrfs-progs: mkfs: Introduce -O bg-tree
>>   btrfs-progs: dump-tree/dump-super: Introduce support for bg tree
>>   btrfs-progs: check: Introduce support for bg-tree feature
>>
>>  check/main.c              |   7 +-
>>  check/mode-lowmem.c       |   9 +-
>>  cmds-inspect-dump-super.c |   3 +-
>>  cmds-inspect-dump-tree.c  |   5 +
>>  ctree.h                   |  17 +-
>>  disk-io.c                 |  29 +++-
>>  extent-tree.c             | 326 +++++++++++++++++++++++++++-----------
>>  fsfeatures.c              |   6 +
>>  mkfs/common.c             |   7 +-
>>  mkfs/common.h             |   1 +
>>  mkfs/main.c               |  57 +++++++
>>  print-tree.c              |   3 +
>>  transaction.c             |   1 +
>>  13 files changed, 365 insertions(+), 106 deletions(-)
>>
> 


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