linux-kernel - [PATCH e2fsprogs v3] libext2fs: fix orphan file size

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Message-Id: <20251120135514.3013973-1-libaokun@huaweicloud.com>
Date: Thu, 20 Nov 2025 21:55:14 +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,
	yi.zhang@...wei.com,
	yangerkun@...wei.com,
	libaokun1@...wei.com,
	libaokun@...weicloud.com
Subject: [PATCH e2fsprogs v3] libext2fs: fix orphan file size > kernel limit with large blocksize

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

Kernel commit 0a6ce20c1564 ("ext4: verify orphan file size is not too big")
limits the maximum supported orphan file size to 8 << 20.

However, in e2fsprogs, the orphan file size is set to 32–512 filesystem
blocks when creating a filesystem.

With 64k block size, formatting an ext4 fs >32G gives an orphan file bigger
than the kernel allows, so mount prints an error and fails:

    EXT4-fs (vdb): orphan file too big: 8650752
    EXT4-fs (vdb): mount failed

Thus, orphan file size is capped at 512 filesystem blocks in both e2fsprogs
and the kernel.

Signed-off-by: Baokun Li <libaokun1@...wei.com>
---
v1->v2:
 * Revert the changes in ext2fs_default_orphan_file_blocks()

v2->v3:
 * Aligning with the old default of 512 filesystem blocks for
   max orphan file size allows existing 64KB block filesystems
   (created under 64KB page size) to mount without error.

v1: https://lore.kernel.org/r/20251112122157.1990595-1-libaokun@huaweicloud.com
v2: https://lore.kernel.org/r/20251113090122.2385797-1-libaokun@huaweicloud.com

 lib/ext2fs/orphan.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/ext2fs/orphan.c b/lib/ext2fs/orphan.c
index 14ac3569..0f1889cb 100644
--- a/lib/ext2fs/orphan.c
+++ b/lib/ext2fs/orphan.c
@@ -15,6 +15,8 @@
 #include "ext2_fs.h"
 #include "ext2fsP.h"
 
+#define EXT4_MAX_ORPHAN_FILE_BLOCKS 512
+
 errcode_t ext2fs_truncate_orphan_file(ext2_filsys fs)
 {
 	struct ext2_inode inode;
@@ -129,6 +131,9 @@ errcode_t ext2fs_create_orphan_file(ext2_filsys fs, blk_t num_blocks)
 	struct ext4_orphan_block_tail *ob_tail;
 	time_t now;
 
+	if (num_blocks > EXT4_MAX_ORPHAN_FILE_BLOCKS)
+		num_blocks = EXT4_MAX_ORPHAN_FILE_BLOCKS;
+
 	if (ino) {
 		err = ext2fs_read_inode(fs, ino, &inode);
 		if (err)
-- 
2.46.1