ext4: factor out block group accounting into functions

This makes it easier to understand how ext4_init_block_bitmap() works,
and it will assist when we split out ext4_free_blocks_after_init() in
the next commit.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index f8224adf496ed91def8db62a83ebe6fb85d890ee..8573e2bfb78a400be5052549fcd0263a6e7dd3d5 100644 (file)
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -23,6 +23,9 @@
 
 #include <trace/events/ext4.h>
 
+static unsigned int num_base_meta_blocks(struct super_block *sb,
+                                        ext4_group_t block_group);
+
 /*
  * balloc.c contains the blocks allocation and deallocation routines
  */
@@ -83,14 +86,30 @@ static int ext4_group_used_meta_blocks(struct super_block *sb,
        return used_blocks;
 }
 
+static unsigned int num_blocks_in_group(struct super_block *sb,
+                                       ext4_group_t block_group)
+{
+       if (block_group == ext4_get_groups_count(sb) - 1) {
+               /*
+                * Even though mke2fs always initializes the first and
+                * last group, just in case some other tool was used,
+                * we need to make sure we calculate the right free
+                * blocks.
+                */
+               return ext4_blocks_count(EXT4_SB(sb)->s_es) -
+                       ext4_group_first_block_no(sb, block_group);
+       } else
+               return EXT4_BLOCKS_PER_GROUP(sb);
+}
+
 /* Initializes an uninitialized block bitmap if given, and returns the
  * number of blocks free in the group. */
 unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
                 ext4_group_t block_group, struct ext4_group_desc *gdp)
 {
-       int bit, bit_max;
+       unsigned int bit, bit_max = num_base_meta_blocks(sb, block_group);
        ext4_group_t ngroups = ext4_get_groups_count(sb);
-       unsigned free_blocks, group_blocks;
+       unsigned group_blocks = num_blocks_in_group(sb, block_group);
        struct ext4_sb_info *sbi = EXT4_SB(sb);
 
        if (bh) {
@@ -110,35 +129,6 @@ unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
                memset(bh->b_data, 0, sb->s_blocksize);
        }
 
-       /* Check for superblock and gdt backups in this group */
-       bit_max = ext4_bg_has_super(sb, block_group);
-
-       if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
-           block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
-                         sbi->s_desc_per_block) {
-               if (bit_max) {
-                       bit_max += ext4_bg_num_gdb(sb, block_group);
-                       bit_max +=
-                               le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
-               }
-       } else { /* For META_BG_BLOCK_GROUPS */
-               bit_max += ext4_bg_num_gdb(sb, block_group);
-       }
-
-       if (block_group == ngroups - 1) {
-               /*
-                * Even though mke2fs always initialize first and last group
-                * if some other tool enabled the EXT4_BG_BLOCK_UNINIT we need
-                * to make sure we calculate the right free blocks
-                */
-               group_blocks = ext4_blocks_count(sbi->s_es) -
-                       ext4_group_first_block_no(sb, ngroups - 1);
-       } else {
-               group_blocks = EXT4_BLOCKS_PER_GROUP(sb);
-       }
-
-       free_blocks = group_blocks - bit_max;
-
        if (bh) {
                ext4_fsblk_t start, tmp;
                int flex_bg = 0;
@@ -176,7 +166,8 @@ unsigned ext4_init_block_bitmap(struct super_block *sb, struct buffer_head *bh,
                ext4_mark_bitmap_end(group_blocks, sb->s_blocksize * 8,
                                     bh->b_data);
        }
-       return free_blocks - ext4_group_used_meta_blocks(sb, block_group, gdp);
+       return group_blocks - bit_max -
+               ext4_group_used_meta_blocks(sb, block_group, gdp);
 }
 
 
@@ -620,6 +611,31 @@ unsigned long ext4_bg_num_gdb(struct super_block *sb, ext4_group_t group)
 
 }
 
+/*
+ * This function returns the number of file system metadata blocks at
+ * the beginning of a block group, including the reserved gdt blocks.
+ */
+static unsigned int num_base_meta_blocks(struct super_block *sb,
+                                        ext4_group_t block_group)
+{
+       struct ext4_sb_info *sbi = EXT4_SB(sb);
+       int num;
+
+       /* Check for superblock and gdt backups in this group */
+       num = ext4_bg_has_super(sb, block_group);
+
+       if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_META_BG) ||
+           block_group < le32_to_cpu(sbi->s_es->s_first_meta_bg) *
+                         sbi->s_desc_per_block) {
+               if (num) {
+                       num += ext4_bg_num_gdb(sb, block_group);
+                       num += le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks);
+               }
+       } else { /* For META_BG_BLOCK_GROUPS */
+               num += ext4_bg_num_gdb(sb, block_group);
+       }
+       return num;
+}
 /**
  *     ext4_inode_to_goal_block - return a hint for block allocation
  *     @inode: inode for block allocation