From: Theodore Ts'o <tytso@mit.edu>
Date: Fri, 15 Apr 2022 01:31:27 +0000 (-0400)
Subject: ext4: fix overhead calculation to account for the reserved gdt blocks
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=10b01ee92df52c8d7200afead4d5e5f55a5c58b1;p=linux.git

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

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
---

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index f2a5e78f93a98..23a9b2c086ed3 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) +