Re: [PATCH v2] mkfs.f2fs: expand scalability of nat bitmap

From: Chao Yu
Date: Tue Jan 16 2018 - 22:15:15 EST

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Hi Jaegeuk,

On 2018/1/17 8:47, Jaegeuk Kim wrote:
> Hi Chao,
>
> On 01/15, Chao Yu wrote:
>> Previously, our total node number (nat_bitmap) and total nat segment count
>> will not monotonously increase along with image size, and max nat_bitmap size
>> is limited by "CHECKSUM_OFFSET - sizeof(struct f2fs_checkpoint) + 1", it is
>> with bad scalability when user wants to create more inode/node in larger image.
>>
>> So this patch tries to relieve the limitation, by default, limitting total nat
>> entry number with 20% of total block number.
>>
>> Before:
>> image_size(GB) nat_bitmap sit_bitmap nat_segment sit_segment
>> 16 3836 64 36 2
>> 32 3836 64 72 2
>> 64 3772 128 116 4
>> 128 3708 192 114 6
>> 256 3580 320 110 10

As you see, nat_segment count will reduce when image size increases
starting from 64GB, that means nat segment count will not monotonously
increase when image size is increasing, so it would be better to active
this when image size is larger than 32GB?

IMO, configuring basic nid ratio to fixed value like ext4 ("free inode" :
"free block" is about 1 : 4) would be better:
a. It will be easy for user to predict nid count or nat segment count with
fix-sized image;
b. If user wants to reserve more nid count, we can support -N option in
mkfs.f2fs to specify total nid count as user wish.

How do you think?

Thanks,

>> 512 3260 640 100 20
>> 1024 2684 1216 82 38
>> 2048 1468 2432 44 76
>> 4096 3900 4800 120 150
>>
>> After:
>> image_size(GB) nat_bitmap sit_bitmap nat_segment sit_segment
>> 16 256 64 8 2
>> 32 512 64 16 2
>> 64 960 128 30 4
>> 128 1856 192 58 6
>> 256 3712 320 116 10
>
> Can we activate this, if size is larger than 256GB or something around that?
>
> Thanks,
>
>> 512 7424 640 232 20
>> 1024 14787 1216 462 38
>> 2048 29504 2432 922 76
>> 4096 59008 4800 1844 150
>>
>> Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
>> ---
>> v2:
>> - add CP_LARGE_NAT_BITMAP_FLAG flag to indicate new layout of nat/sit bitmap.
>> fsck/f2fs.h | 19 +++++++++++++------
>> fsck/resize.c | 35 +++++++++++++++++------------------
>> include/f2fs_fs.h | 8 ++++++--
>> lib/libf2fs.c | 1 +
>> mkfs/f2fs_format.c | 45 +++++++++++++++++++++++----------------------
>> 5 files changed, 60 insertions(+), 48 deletions(-)
>>
>> diff --git a/fsck/f2fs.h b/fsck/f2fs.h
>> index f5970d9dafc0..8a5ce365282d 100644
>> --- a/fsck/f2fs.h
>> +++ b/fsck/f2fs.h
>> @@ -239,6 +239,12 @@ static inline unsigned int ofs_of_node(struct f2fs_node *node_blk)
>> return flag >> OFFSET_BIT_SHIFT;
>> }
>>
>> +static inline bool is_set_ckpt_flags(struct f2fs_checkpoint *cp, unsigned int f)
>> +{
>> + unsigned int ckpt_flags = le32_to_cpu(cp->ckpt_flags);
>> + return ckpt_flags & f ? 1 : 0;
>> +}
>> +
>> static inline unsigned long __bitmap_size(struct f2fs_sb_info *sbi, int flag)
>> {
>> struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
>> @@ -256,6 +262,13 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
>> {
>> struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
>> int offset;
>> +
>> + if (is_set_ckpt_flags(ckpt, CP_LARGE_NAT_BITMAP_FLAG)) {
>> + offset = (flag == SIT_BITMAP) ?
>> + le32_to_cpu(ckpt->nat_ver_bitmap_bytesize) : 0;
>> + return &ckpt->sit_nat_version_bitmap + offset;
>> + }
>> +
>> if (le32_to_cpu(F2FS_RAW_SUPER(sbi)->cp_payload) > 0) {
>> if (flag == NAT_BITMAP)
>> return &ckpt->sit_nat_version_bitmap;
>> @@ -268,12 +281,6 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag)
>> }
>> }
>>
>> -static inline bool is_set_ckpt_flags(struct f2fs_checkpoint *cp, unsigned int f)
>> -{
>> - unsigned int ckpt_flags = le32_to_cpu(cp->ckpt_flags);
>> - return ckpt_flags & f ? 1 : 0;
>> -}
>> -
>> static inline block_t __start_cp_addr(struct f2fs_sb_info *sbi)
>> {
>> block_t start_addr = le32_to_cpu(F2FS_RAW_SUPER(sbi)->cp_blkaddr);
>> diff --git a/fsck/resize.c b/fsck/resize.c
>> index 143ad5d3c0a1..f3547c86f351 100644
>> --- a/fsck/resize.c
>> +++ b/fsck/resize.c
>> @@ -13,10 +13,10 @@ static int get_new_sb(struct f2fs_super_block *sb)
>> {
>> u_int32_t zone_size_bytes, zone_align_start_offset;
>> u_int32_t blocks_for_sit, blocks_for_nat, blocks_for_ssa;
>> - u_int32_t sit_segments, diff, total_meta_segments;
>> + u_int32_t sit_segments, nat_segments, diff, total_meta_segments;
>> u_int32_t total_valid_blks_available;
>> u_int32_t sit_bitmap_size, max_sit_bitmap_size;
>> - u_int32_t max_nat_bitmap_size, max_nat_segments;
>> + u_int32_t max_nat_bitmap_size;
>> u_int32_t segment_size_bytes = 1 << (get_sb(log_blocksize) +
>> get_sb(log_blocks_per_seg));
>> u_int32_t blks_per_seg = 1 << get_sb(log_blocks_per_seg);
>> @@ -47,7 +47,15 @@ static int get_new_sb(struct f2fs_super_block *sb)
>> get_sb(segment_count_sit))) * blks_per_seg;
>> blocks_for_nat = SIZE_ALIGN(total_valid_blks_available,
>> NAT_ENTRY_PER_BLOCK);
>> - set_sb(segment_count_nat, SEG_ALIGN(blocks_for_nat));
>> + nat_segments = SEG_ALIGN(blocks_for_nat) *
>> + DEFAULT_NAT_ENTRY_RATIO / 100;
>> + set_sb(segment_count_nat, nat_segments ? nat_segments : 1);
>> +
>> + max_nat_bitmap_size = (get_sb(segment_count_nat) <<
>> + get_sb(log_blocks_per_seg)) / 8;
>> + set_sb(segment_count_nat, get_sb(segment_count_nat) * 2);
>> +
>> + c.large_nat_bitmap = 1;
>>
>> sit_bitmap_size = ((get_sb(segment_count_sit) / 2) <<
>> get_sb(log_blocks_per_seg)) / 8;
>> @@ -56,25 +64,16 @@ static int get_new_sb(struct f2fs_super_block *sb)
>> else
>> max_sit_bitmap_size = sit_bitmap_size;
>>
>> - /*
>> - * It should be reserved minimum 1 segment for nat.
>> - * When sit is too large, we should expand cp area. It requires more pages for cp.
>> - */
>> - if (max_sit_bitmap_size > MAX_SIT_BITMAP_SIZE_IN_CKPT) {
>> - max_nat_bitmap_size = CHECKSUM_OFFSET - sizeof(struct f2fs_checkpoint) + 1;
>> - set_sb(cp_payload, F2FS_BLK_ALIGN(max_sit_bitmap_size));
>> + /* use cp_payload if free space of f2fs_checkpoint is not enough */
>> + if (max_sit_bitmap_size + max_nat_bitmap_size >
>> + MAX_BITMAP_SIZE_IN_CKPT) {
>> + u_int32_t diff = max_sit_bitmap_size + max_nat_bitmap_size -
>> + MAX_BITMAP_SIZE_IN_CKPT;
>> + set_sb(cp_payload, F2FS_BLK_ALIGN(diff));
>> } else {
>> - max_nat_bitmap_size = CHECKSUM_OFFSET - sizeof(struct f2fs_checkpoint) + 1
>> - - max_sit_bitmap_size;
>> set_sb(cp_payload, 0);
>> }
>>
>> - max_nat_segments = (max_nat_bitmap_size * 8) >>
>> - get_sb(log_blocks_per_seg);
>> -
>> - if (get_sb(segment_count_nat) > max_nat_segments)
>> - set_sb(segment_count_nat, max_nat_segments);
>> -
>> set_sb(segment_count_nat, get_sb(segment_count_nat) * 2);
>>
>> set_sb(ssa_blkaddr, get_sb(nat_blkaddr) +
>> diff --git a/include/f2fs_fs.h b/include/f2fs_fs.h
>> index 4739085ed98f..edf351412702 100644
>> --- a/include/f2fs_fs.h
>> +++ b/include/f2fs_fs.h
>> @@ -362,6 +362,7 @@ struct f2fs_configuration {
>> int preen_mode;
>> int ro;
>> int preserve_limits; /* preserve quota limits */
>> + int large_nat_bitmap;
>> __le32 feature; /* defined features */
>>
>> /* defragmentation parameters */
>> @@ -613,6 +614,7 @@ struct f2fs_super_block {
>> /*
>> * For checkpoint
>> */
>> +#define CP_LARGE_NAT_BITMAP_FLAG 0x00000200
>> #define CP_TRIMMED_FLAG 0x00000100
>> #define CP_NAT_BITS_FLAG 0x00000080
>> #define CP_CRC_RECOVERY_FLAG 0x00000040
>> @@ -657,8 +659,8 @@ struct f2fs_checkpoint {
>> unsigned char sit_nat_version_bitmap[1];
>> } __attribute__((packed));
>>
>> -#define MAX_SIT_BITMAP_SIZE_IN_CKPT \
>> - (CHECKSUM_OFFSET - sizeof(struct f2fs_checkpoint) + 1 - 64)
>> +#define MAX_BITMAP_SIZE_IN_CKPT \
>> + (CHECKSUM_OFFSET - sizeof(struct f2fs_checkpoint) + 1)
>>
>> /*
>> * For orphan inode management
>> @@ -846,6 +848,8 @@ struct f2fs_node {
>> #define NAT_ENTRY_PER_BLOCK (PAGE_CACHE_SIZE / sizeof(struct f2fs_nat_entry))
>> #define NAT_BLOCK_OFFSET(start_nid) (start_nid / NAT_ENTRY_PER_BLOCK)
>>
>> +#define DEFAULT_NAT_ENTRY_RATIO 20
>> +
>> #ifdef ANDROID_WINDOWS_HOST
>> #pragma pack(1)
>> #endif
>> diff --git a/lib/libf2fs.c b/lib/libf2fs.c
>> index ffdbccb34627..e8b1842b7391 100644
>> --- a/lib/libf2fs.c
>> +++ b/lib/libf2fs.c
>> @@ -623,6 +623,7 @@ void f2fs_init_configuration(void)
>> c.ro = 0;
>> c.kd = -1;
>> c.dry_run = 0;
>> + c.large_nat_bitmap = 0;
>> c.fixed_time = -1;
>> }
>>
>> diff --git a/mkfs/f2fs_format.c b/mkfs/f2fs_format.c
>> index a13000184300..23eaf40c5962 100644
>> --- a/mkfs/f2fs_format.c
>> +++ b/mkfs/f2fs_format.c
>> @@ -151,13 +151,13 @@ static int f2fs_prepare_super_block(void)
>> u_int32_t log_sectorsize, log_sectors_per_block;
>> u_int32_t log_blocksize, log_blks_per_seg;
>> u_int32_t segment_size_bytes, zone_size_bytes;
>> - u_int32_t sit_segments;
>> + u_int32_t sit_segments, nat_segments;
>> u_int32_t blocks_for_sit, blocks_for_nat, blocks_for_ssa;
>> u_int32_t total_valid_blks_available;
>> u_int64_t zone_align_start_offset, diff;
>> u_int64_t total_meta_zones, total_meta_segments;
>> u_int32_t sit_bitmap_size, max_sit_bitmap_size;
>> - u_int32_t max_nat_bitmap_size, max_nat_segments;
>> + u_int32_t max_nat_bitmap_size;
>> u_int32_t total_zones;
>> u_int32_t next_ino;
>> enum quota_type qtype;
>> @@ -272,7 +272,18 @@ static int f2fs_prepare_super_block(void)
>> blocks_for_nat = SIZE_ALIGN(total_valid_blks_available,
>> NAT_ENTRY_PER_BLOCK);
>>
>> - set_sb(segment_count_nat, SEG_ALIGN(blocks_for_nat));
>> + nat_segments = SEG_ALIGN(blocks_for_nat) *
>> + DEFAULT_NAT_ENTRY_RATIO / 100;
>> +
>> + set_sb(segment_count_nat, nat_segments ? nat_segments : 1);
>> +
>> + max_nat_bitmap_size = (get_sb(segment_count_nat) <<
>> + log_blks_per_seg) / 8;
>> +
>> + set_sb(segment_count_nat, get_sb(segment_count_nat) * 2);
>> +
>> + c.large_nat_bitmap = 1;
>> +
>> /*
>> * The number of node segments should not be exceeded a "Threshold".
>> * This number resizes NAT bitmap area in a CP page.
>> @@ -286,29 +297,16 @@ static int f2fs_prepare_super_block(void)
>> else
>> max_sit_bitmap_size = sit_bitmap_size;
>>
>> - /*
>> - * It should be reserved minimum 1 segment for nat.
>> - * When sit is too large, we should expand cp area. It requires more
>> - * pages for cp.
>> - */
>> - if (max_sit_bitmap_size > MAX_SIT_BITMAP_SIZE_IN_CKPT) {
>> - max_nat_bitmap_size = CHECKSUM_OFFSET -
>> - sizeof(struct f2fs_checkpoint) + 1;
>> - set_sb(cp_payload, F2FS_BLK_ALIGN(max_sit_bitmap_size));
>> + /* use cp_payload if free space of f2fs_checkpoint is not enough */
>> + if (max_sit_bitmap_size + max_nat_bitmap_size >
>> + MAX_BITMAP_SIZE_IN_CKPT) {
>> + u_int32_t diff = max_sit_bitmap_size + max_nat_bitmap_size -
>> + MAX_BITMAP_SIZE_IN_CKPT;
>> + set_sb(cp_payload, F2FS_BLK_ALIGN(diff));
>> } else {
>> - max_nat_bitmap_size =
>> - CHECKSUM_OFFSET - sizeof(struct f2fs_checkpoint) + 1
>> - - max_sit_bitmap_size;
>> set_sb(cp_payload, 0);
>> }
>>
>> - max_nat_segments = (max_nat_bitmap_size * 8) >> log_blks_per_seg;
>> -
>> - if (get_sb(segment_count_nat) > max_nat_segments)
>> - set_sb(segment_count_nat, max_nat_segments);
>> -
>> - set_sb(segment_count_nat, get_sb(segment_count_nat) * 2);
>> -
>> set_sb(ssa_blkaddr, get_sb(nat_blkaddr) + get_sb(segment_count_nat) *
>> c.blks_per_seg);
>>
>> @@ -622,6 +620,9 @@ static int f2fs_write_check_point_pack(void)
>> if (c.trimmed)
>> flags |= CP_TRIMMED_FLAG;
>>
>> + if (c.large_nat_bitmap)
>> + flags |= CP_LARGE_NAT_BITMAP_FLAG;
>> +
>> set_cp(ckpt_flags, flags);
>> set_cp(cp_pack_start_sum, 1 + get_sb(cp_payload));
>> set_cp(valid_node_count, 1 + quota_inum);
>> --
>> 2.15.0.55.gc2ece9dc4de6
>
> .
>

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