linux-ext4 - [PATCH AUTOSEL 5.15 01/23] ext4: avoid dividing by 0 in mb_update_avg_fragment

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Date: Wed,  7 Feb 2024 16:25:42 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Baokun Li <libaokun1@...wei.com>,
	Jan Kara <jack@...e.cz>,
	Theodore Ts'o <tytso@....edu>,
	Sasha Levin <sashal@...nel.org>,
	adilger.kernel@...ger.ca,
	linux-ext4@...r.kernel.org
Subject: [PATCH AUTOSEL 5.15 01/23] ext4: avoid dividing by 0 in mb_update_avg_fragment_size() when block bitmap corrupt

From: Baokun Li <libaokun1@...wei.com>

[ Upstream commit 993bf0f4c393b3667830918f9247438a8f6fdb5b ]

Determine if bb_fragments is 0 instead of determining bb_free to eliminate
the risk of dividing by zero when the block bitmap is corrupted.

Signed-off-by: Baokun Li <libaokun1@...wei.com>
Reviewed-by: Jan Kara <jack@...e.cz>
Link: https://lore.kernel.org/r/20240104142040.2835097-6-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@....edu>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/ext4/mballoc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index e44c28ceb9cd..3df3c3894f7b 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -853,7 +853,7 @@ mb_update_avg_fragment_size(struct super_block *sb, struct ext4_group_info *grp)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 
-	if (!test_opt2(sb, MB_OPTIMIZE_SCAN) || grp->bb_free == 0)
+	if (!test_opt2(sb, MB_OPTIMIZE_SCAN) || grp->bb_fragments == 0)
 		return;
 
 	write_lock(&sbi->s_mb_rb_lock);
-- 
2.43.0