linux-kernel - [PATCH v2 07/24] ext4: support large block size in ext4_calculate

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20251107144249.435029-8-libaokun@huaweicloud.com>
Date: Fri,  7 Nov 2025 22:42:32 +0800
From: libaokun@...weicloud.com
To: linux-ext4@...r.kernel.org
Cc: tytso@....edu,
	adilger.kernel@...ger.ca,
	jack@...e.cz,
	linux-kernel@...r.kernel.org,
	kernel@...kajraghav.com,
	mcgrof@...nel.org,
	ebiggers@...nel.org,
	willy@...radead.org,
	yi.zhang@...wei.com,
	yangerkun@...wei.com,
	chengzhihao1@...wei.com,
	libaokun1@...wei.com,
	libaokun@...weicloud.com
Subject: [PATCH v2 07/24] ext4: support large block size in ext4_calculate_overhead()

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

ext4_calculate_overhead() used a single page for its bitmap buffer, which
worked fine when PAGE_SIZE >= block size. However, with block size greater
than page size (BS > PS) support, the bitmap can exceed a single page.

To address this, we now use kvmalloc() to allocate memory of the filesystem
block size, to properly support BS > PS.

Suggested-by: Jan Kara <jack@...e.cz>
Signed-off-by: Baokun Li <libaokun1@...wei.com>
Reviewed-by: Zhang Yi <yi.zhang@...wei.com>
---
 fs/ext4/super.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index a6314a3de51d..0d32370a459a 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4189,7 +4189,7 @@ int ext4_calculate_overhead(struct super_block *sb)
 	unsigned int j_blocks, j_inum = le32_to_cpu(es->s_journal_inum);
 	ext4_group_t i, ngroups = ext4_get_groups_count(sb);
 	ext4_fsblk_t overhead = 0;
-	char *buf = (char *) get_zeroed_page(GFP_NOFS);
+	char *buf = kvmalloc(sb->s_blocksize, GFP_NOFS | __GFP_ZERO);
 
 	if (!buf)
 		return -ENOMEM;
@@ -4214,7 +4214,7 @@ int ext4_calculate_overhead(struct super_block *sb)
 		blks = count_overhead(sb, i, buf);
 		overhead += blks;
 		if (blks)
-			memset(buf, 0, PAGE_SIZE);
+			memset(buf, 0, sb->s_blocksize);
 		cond_resched();
 	}
 
@@ -4237,7 +4237,7 @@ int ext4_calculate_overhead(struct super_block *sb)
 	}
 	sbi->s_overhead = overhead;
 	smp_wmb();
-	free_page((unsigned long) buf);
+	kvfree(buf);
 	return 0;
 }
 
-- 
2.46.1