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
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
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 <yuch...@huawei.com>
---
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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