ext4: fix overhead calculation to account for the reserved gdt blocks

commit 10b01ee92df52c8d7200afead4d5e5f55a5c58b1 upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index dd424958be60c6a4b562d8ea99bd1e69383b39bc..002b7782c2b5159625f79066738228e37efc8709 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3366,9 +3366,11 @@ 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) +