From 10b01ee92df52c8d7200afead4d5e5f55a5c58b1 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Thu, 14 Apr 2022 21:31:27 -0400
Subject: [PATCH] ext4: fix overhead calculation to account for the reserved
 gdt blocks
Git-commit: 10b01ee92df52c8d7200afead4d5e5f55a5c58b1
Patch-mainline: v5.18-rc4
References: bsc#1200869

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
Acked-by: Jan Kara <jack@suse.cz>

---
 fs/ext4/super.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index f2a5e78f93a9..23a9b2c086ed 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -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) +
-- 
2.35.3