ext4: fix overhead calculation to account for the reserved gdt blocks
authorTheodore Ts'o <tytso@mit.edu>
Fri, 15 Apr 2022 01:31:27 +0000 (21:31 -0400)
committerTheodore Ts'o <tytso@mit.edu>
Fri, 15 Apr 2022 01:31:27 +0000 (21:31 -0400)
The kernel calculation was underestimating the overhead by not taking
into account the reserved gdt blocks.  With this change, the overhead
calculated by the kernel matches the overhead calculation in mke2fs.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
fs/ext4/super.c

index f2a5e78..23a9b2c 100644 (file)
@@ -4177,9 +4177,11 @@ static int count_overhead(struct super_block *sb, ext4_group_t grp,
        ext4_fsblk_t            first_block, last_block, b;
        ext4_group_t            i, ngroups = ext4_get_groups_count(sb);
        int                     s, j, count = 0;
+       int                     has_super = ext4_bg_has_super(sb, grp);
 
        if (!ext4_has_feature_bigalloc(sb))
-               return (ext4_bg_has_super(sb, grp) + ext4_bg_num_gdb(sb, grp) +
+               return (has_super + ext4_bg_num_gdb(sb, grp) +
+                       (has_super ? le16_to_cpu(sbi->s_es->s_reserved_gdt_blocks) : 0) +
                        sbi->s_itb_per_group + 2);
 
        first_block = le32_to_cpu(sbi->s_es->s_first_data_block) +