Hi Chao, On 2016/2/23 17:46, Chao Yu wrote: > Hi Junling, > >> -----Original Message----- >> From: Junling Zheng [mailto:zhengjunl...@huawei.com] >> Sent: Tuesday, February 23, 2016 3:20 PM >> To: Chao Yu; jaeg...@kernel.org >> Cc: linux-f2fs-devel@lists.sourceforge.net >> Subject: Re: [f2fs-dev] [RFC PATCH v2] mkfs.f2fs: recalculate sit_segments by >> max_sit_bitmap_size >> >> On 2016/2/23 13:28, Chao Yu wrote: >>> Hi all, >>> >>>> -----Original Message----- >>>> From: Junling Zheng [mailto:zhengjunl...@huawei.com] >>>> Sent: Tuesday, February 23, 2016 11:47 AM >>>> To: linux-f2fs-devel@lists.sourceforge.net; jaeg...@kernel.org >>>> Subject: [f2fs-dev] [RFC PATCH v2] mkfs.f2fs: recalculate sit_segments by >>>> max_sit_bitmap_size >>>> >>>> In most cases, sit_bitmap_size is smaller than MAX_SIT_BITMAP_SIZE. >>>> >>>> However, in some extreme scenarios, such as 16TB, sit_bitmap_size >>>> could be larger than MAX_SIT_BITMAP_SIZE. >>>> >>>> In this case, we should recalculate the sit_segments through >>>> max_sit_bitmap_size to prevent sit_ver_bitmap_bytesize got from >>>> segment_count_sit in f2fs_write_check_point_pack() being over >>>> MAX_SIT_BITMAP_SIZE. >>>> >>>> Signed-off-by: Junling Zheng <zhengjunl...@huawei.com> >>>> --- >>>> mkfs/f2fs_format.c | 23 ++++++++++++++++------- >>>> 1 file changed, 16 insertions(+), 7 deletions(-) >>>> >>>> diff --git a/mkfs/f2fs_format.c b/mkfs/f2fs_format.c >>>> index 645c2aa..3a050e0 100644 >>>> --- a/mkfs/f2fs_format.c >>>> +++ b/mkfs/f2fs_format.c >>>> @@ -191,6 +191,22 @@ static int f2fs_prepare_super_block(void) >>>> >>>> sit_segments = SEG_ALIGN(blocks_for_sit); >>>> >>>> + /* >>>> + * In most cases, sit_bitmap_size is smaller than MAX_SIT_BITMAP_SIZE. >>>> + * However, in an extreme scenario(16TB), sit_bitmap_size could be >>>> larger >>>> + * than MAX_SIT_BITMAP_SIZE. Thus, we should recalculate the >>>> sit_segments >>>> + * to prevent sit_ver_bitmap_bytesize got from segment_count_sit in >>>> + * f2fs_write_check_point_pack() being over MAX_SIT_BITMAP_SIZE. >>>> + */ >>>> + sit_bitmap_size = (sit_segments << log_blks_per_seg) / 8; >>>> + >>>> + if (sit_bitmap_size > MAX_SIT_BITMAP_SIZE) { >>>> + max_sit_bitmap_size = MAX_SIT_BITMAP_SIZE; >>>> + sit_segments = max_sit_bitmap_size * 8 >> log_blks_per_seg; >>>> + blocks_for_sit = sit_segments << log_blks_per_seg; >>>> + } else >>> >>> Still the minor coding style problem. >>> >> >> Do you mean the "else" also needs {} even though it has only one sentence? > > That's right. > >> >>> IMO, maybe it would be better to limit config.total_sectors with 16TB at >>> very beginning, so more fields in sb like block_count, segment_count could >>> be set correctly when we try to format a huge size image. Right? >>> >> >> Limiting the disk at very beginning means not starting from 0 sector? > > Oh, what I mean here is 'at very beginning time', f2fs can support a > volume with size of 16 TB at most, so I'm thinking we'd better do the > limitation for config.total_sectors, then most parameters in cp/sb > calculated according to value of total_sectors could be limited or > corrected too. > > Anyway, that is a separate issue. :) >
Good idea! I'll send another patch later:) >> Does it amount to reducing the size of disk to keep sit_bitmap_size smaller >> than MAX_SIT_BITMAP_SIZE? It looks to be helpful:) >> >> Indeed, the data in sb have no problem. Just the difference of calculating >> methods between sit_bitmap_size and MAX_SIT_BITMAP_SIZE: >> >> F2FS_MAX_SEGMENT: >> 16 * 1024 * 1024 / 2 = 8388608 >> max blocks_for_sit: >> ALIGN(F2FS_MAX_SEGMENT, SIT_ENTRY_PER_BLOCK) = 152521 // Upward here, >> not all blocks are >> used, some are redundant. >> max sit_segments: >> ALIGN(blocks_for_sit, config.blks_per_seg) = 298 // Upward here, >> not all segments are >> used, some are redundant. >> max segment_count_sit: >> sit_segments * 2 = 596 >> max sit_ver_bitmap_bytesize: >> ((segment_count_sit / 2) << log_blocks_per_seg) / 8 = 19072 // >> Here, bitmap size is too >> large because of the redundant blocks and segments. >> >> However, MAX_SIT_BITMAP_SIZE is defined as: >> ((F2FS_MAX_SEGMENT / SIT_ENTRY_PER_BLOCK) / 8) = 19065 // Downward >> here, abandon the >> redundant segments. >> >> So, the best way is to unify the two calculating method:) > > Agreed. :) > So I'll resend a fix by redefining MAX_SIT_BITMAP_SIZE as the following instead of recalculating segment_count_sit:) SEG_ALIGN(ALIGN(F2FS_MAX_SEGMENT, SIT_ENTRY_PER_BLOCK)) * config.blks_per_seg / 8 Thanks, > Thanks, > >> >> Thanks, >> >>> Thanks, >>> >>>> + max_sit_bitmap_size = sit_bitmap_size; >>>> + >>>> set_sb(segment_count_sit, sit_segments * 2); >>>> >>>> set_sb(nat_blkaddr, get_sb(sit_blkaddr) + get_sb(segment_count_sit) * >>>> @@ -208,13 +224,6 @@ static int f2fs_prepare_super_block(void) >>>> * This number resizes NAT bitmap area in a CP page. >>>> * So the threshold is determined not to overflow one CP page >>>> */ >>>> - sit_bitmap_size = ((get_sb(segment_count_sit) / 2) << >>>> - log_blks_per_seg) / 8; >>>> - >>>> - if (sit_bitmap_size > MAX_SIT_BITMAP_SIZE) >>>> - max_sit_bitmap_size = MAX_SIT_BITMAP_SIZE; >>>> - else >>>> - max_sit_bitmap_size = sit_bitmap_size; >>>> >>>> /* >>>> * It should be reserved minimum 1 segment for nat. >>>> -- >>>> 1.9.1 >>>> >>>> >>>> ------------------------------------------------------------------------------ >>>> 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 >>>> _______________________________________________ >>>> Linux-f2fs-devel mailing list >>>> Linux-f2fs-devel@lists.sourceforge.net >>>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel >>> >>> >>> . >>> >> > > > > . > ------------------------------------------------------------------------------ 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 _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
