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 e17a6396bde6cf3b801ac7b7e33a6f9308ba7268..593f7f80a12ef20fda48437dbda2fdfb78fcb04d 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3241,9 +3241,11 @@ 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) +