From: Baokun Li <libaokun1@huawei.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@huawei.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

On Thu 20-11-25 21:55:14, libaokun@huaweicloud.com wrote:
> From: Baokun Li <libaokun1@huawei.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@huawei.com>

So finally we should have this consistent :). Thanks for working on this.
Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

									Honza

> ---
> 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
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR