Re: [PATCH] btrfs-progs: convert: prevent data chunks to go beyond device size

[Qu Wenruo <wqu@suse.com>]

在 2025/10/30 23:54, Filipe Manana 写道:
> On Thu, Oct 30, 2025 at 4:17 AM Yuwei Han <hrx@bupt.moe> wrote:
>>
>>
>>
>> 在 2025/10/25 07:30, Qu Wenruo 写道:
>>> [BUG]
>>> There is a bug report that kernel is rejecting a converted btrfs that
>>> has dev extents beyond device boundary.
>>>
>>> The invovled device extent is at 999627694980, length is 30924800,
>>> meanwhile the device is 999658557440.
>>>
>>> The device is size not aligned to 64K, meanwhile the dev extent is
>>> aligned to 64K.
>>>
>>> [CAUSE]
>>> For converted btrfs, the source fs has all its freedom to choose its
>>> size, as long as it's aligned to the fs block size.
>>>
>>> So when adding new converted data block groups we need to do extra
>>> alignment, but in make_convert_data_block_groups() we are rounding up
>>> the end, which can exceed the device size.
>>>
>>> [FIX]
>>> Instead of rounding up to stripe boundary, rounding it down to prevent
>>> going beyond the device boundary.
>>>
>> Reported-by: Andieqqq <zeige265975@gmail.com>
> 
> While at it, also add a Link tag pointing to the report....

Sorry, no public report available.

I got a lot of private reports forwarded from Yuwei, as a lot of people 
behind the Great Firewall are not used to github/mail to report a bug.

And this is one example of such private report.

Thanks,
Qu

> 
>> Signed-off-by: Qu Wenruo
>> <wqu@suse.com>
>>> ---
>>>    convert/main.c | 4 ++--
>>>    1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/convert/main.c b/convert/main.c
>>> index e279e3d40c5f..5c40c08ddd72 100644
>>> --- a/convert/main.c
>>> +++ b/convert/main.c
>>> @@ -948,8 +948,8 @@ static int make_convert_data_block_groups(struct btrfs_trans_handle *trans,
>>>                        u64 cur_backup = cur;
>>>
>>>                        len = min(max_chunk_size,
>>> -                               round_up(cache->start + cache->size,
>>> -                                        BTRFS_STRIPE_LEN) - cur);
>>> +                               round_down(cache->start + cache->size,
>>> +                                          BTRFS_STRIPE_LEN) - cur);
>>>                        ret = btrfs_alloc_data_chunk(trans, fs_info, &cur_backup, len);
>>>                        if (ret < 0)
>>>                                break;
>>