Re: [PATCH v2] f2fs-tools: set segment_count in super block correctly

[Junling Zheng <zhengjunling@huawei.com>]

On 2016/2/4 17:33, Fan Li wrote:
> 
> 
>> -----Original Message-----
>> From: Junling Zheng [mailto:zhengjunling@huawei.com]
>> Sent: Thursday, February 04, 2016 10:52 AM
>> To: Fan Li; 'Jaegeuk Kim'; heyunlei@huawei.com
>> Cc: linux-f2fs-devel@lists.sourceforge.net
>> Subject: Re: [f2fs-dev] [PATCH v2] f2fs-tools: set segment_count in super block correctly
>>
>> On 2016/2/3 13:29, Fan Li wrote:
>>> Now f2fs will check statistics recorded in super block in
>>> sanity_check_area_boundary() during mount,if number of segments per
>>> section is greater than 1, and the disk space isn't aligned with
>>> section,
>>
>> Hi Fan, Hi Kim:
>>
>> I'm uncertain about which unit the disk space should be aligned with? section or zone?
>>
>> It looks like commit "e9dfbbb"(mkfs.f2fs: introduce zone align for main area)
>>
>> from Yunlei had changed the aligning unit from section to zone.
>>
>> So, should segment_count in superblock be aligned with zone rather than section?
> 
> I'm afraid that my codes of mkfs is too old, it doesn't contain this patch, and it still
> uses section size to align main area.
> 

Yeah, this patch is contained on dev branch, not yet on master:)

> Of course if main area should be aligned with zone, the following patch should be
> modified accordingly.
> 
>>
>> Thanks,
>>
>> Junling
>>
>>> mount will fail due to following condition:
>>>
>>> main_blkaddr + (segment_count_main << log_blocks_per_seg) !=
>>> 		segment0_blkaddr + (segment_count << log_blocks_per_seg)
>>>
>>> this is because when the length of main area isn't aligned with
>>> section, mkfs didn't add the number of excess segments to
>>> segment_count_main, but add it to segment_count.
>>> Here align segment_count with section size first to prevent such problem.
>>>
>>> Signed-off-by: Fan Li <fanofcode.li@samsung.com>
>>> ---
>>>  mkfs/f2fs_format.c |    3 ++-
>>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/mkfs/f2fs_format.c b/mkfs/f2fs_format.c index
>>> 66d7342..3366302 100644
>>> --- a/mkfs/f2fs_format.c
>>> +++ b/mkfs/f2fs_format.c
>>> @@ -174,7 +174,8 @@ static int f2fs_prepare_super_block(void)
>>>         }
>>>
>>>         set_sb(segment_count, (config.total_sectors * config.sector_size -
>>> -                               zone_align_start_offset) / segment_size_bytes);
>>> +                               zone_align_start_offset) / segment_size_bytes /
>>> +                               config.segs_per_sec *
>>> + config.segs_per_sec);
>>>
>>>         set_sb(segment0_blkaddr, zone_align_start_offset / blk_size_bytes);
>>>         sb->cp_blkaddr = sb->segment0_blkaddr;
>>>
>>
> 
> 
> 
> .
> 



------------------------------------------------------------------------------
Site24x7 APM Insight: Get Deep Visibility into Application Performance
APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month
Monitor end-to-end web transactions and take corrective actions now
Troubleshoot faster and improve end-user experience. Signup Now!
http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140