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. :) > 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. :) 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
