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From: "Theodore Ts'o" <tytso@mit.edu>
To: Ext4 Developers List <linux-ext4@vger.kernel.org>
Cc: Fariya F <fariya.fatima03@gmail.com>,
	"Theodore Ts'o" <tytso@mit.edu>,
	stable@kernel.org
Subject: [PATCH 1/3] ext4: fix overhead calculation to account for the reserved gdt blocks
Date: Thu, 14 Apr 2022 22:54:38 -0400	[thread overview]
Message-ID: <20220415025440.2342107-1-tytso@mit.edu> (raw)
In-Reply-To: <CACA3K+iNFkLLuXJ7W5N70sVC+RVVszx-xVQojNUE8NqfWFuSVg@mail.gmail.com>

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 | 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) +
-- 
2.31.0


  reply	other threads:[~2022-04-15  2:55 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-25  6:42 df returns incorrect size of partition due to huge overhead block count in ext4 partition Fariya F
2022-03-25 22:11 ` Theodore Ts'o
2022-03-28 16:08   ` Fariya F
2022-03-29 13:08     ` Theodore Ts'o
2022-04-12  8:56       ` Fariya F
2022-04-15  2:54         ` Theodore Ts'o [this message]
2022-04-15  2:54           ` [PATCH 2/3] ext4: force overhead calculation if the s_overhead_cluster makes no sense Theodore Ts'o
2022-04-15  2:54           ` [PATCH 3/3] ext4: update the cached overhead value in the superblock Theodore Ts'o
2022-04-15 14:41         ` df returns incorrect size of partition due to huge overhead block count in ext4 partition Theodore Ts'o

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