[U-Boot] [PATCH 2/7] ext4: determine group descriptor size for 64bit feature

[Kever Yang]

Hi Stefan, Tom,

     I'm using genext2fs command in Linux to generate my boot image for
kernel and its dtb, my command is like this:
     $ genext2fs -b 32768 -B $((32*1024*1024/32768)) -d boot/ -i 8192 -U 
boot.img

     In the latest version of U-Boot, the image from above command is 
not able
to be mount. After debug, I found out that the root cause is that the 
genext2fs
does not have a initial value for revision_level in super block. After I 
do the mount
and umount for the image in Linux, the U-Boot then can mount the image.

     Is it possible to still support the ext2 image generated by 
genext2fs command in U-Boot?

Thanks,
- Kever
On 09/17/2016 08:10 AM, Stefan Brüns wrote:
> If EXT4_FEATURE_INCOMPAT_64BIT is set, the descriptor can be read from
> the superblocks, otherwise it defaults to 32.
>
> Signed-off-by: Stefan Brüns <stefan.bruens at rwth-aachen.de>
> ---
>   fs/ext4/ext4_common.c | 18 ++++++++++++++----
>   include/ext4fs.h      |  2 ++
>   2 files changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
> index a78b0b8..416a9db 100644
> --- a/fs/ext4/ext4_common.c
> +++ b/fs/ext4/ext4_common.c
> @@ -2233,13 +2233,23 @@ int ext4fs_mount(unsigned part_length)
>   		goto fail;
>   	}
>   
> -	if (le32_to_cpu(data->sblock.revision_level) == 0)
> +	if (le32_to_cpu(data->sblock.revision_level) == 0) {
>   		fs->inodesz = 128;
> -	else
> +	} else {
> +		debug("EXT4 features COMPAT: %08x INCOMPAT: %08x RO_COMPAT: %08x\n",
> +		      __le32_to_cpu(data->sblock.feature_compatibility),
> +		      __le32_to_cpu(data->sblock.feature_incompat),
> +		      __le32_to_cpu(data->sblock.feature_ro_compat));
> +
>   		fs->inodesz = le16_to_cpu(data->sblock.inode_size);
> +		fs->gdsize = le32_to_cpu(data->sblock.feature_incompat) &
> +			EXT4_FEATURE_INCOMPAT_64BIT ?
> +			le16_to_cpu(data->sblock.descriptor_size) : 32;
> +	}
>   
> -	debug("EXT2 rev %d, inode_size %d\n",
> -	       le32_to_cpu(data->sblock.revision_level), fs->inodesz);
> +	debug("EXT2 rev %d, inode_size %d, descriptor size %d\n",
> +	      le32_to_cpu(data->sblock.revision_level),
> +	      fs->inodesz, fs->gdsize);
>   
>   	data->diropen.data = data;
>   	data->diropen.ino = 2;
> diff --git a/include/ext4fs.h b/include/ext4fs.h
> index 6e31c73..7e1ee6c 100644
> --- a/include/ext4fs.h
> +++ b/include/ext4fs.h
> @@ -87,6 +87,8 @@ struct ext_filesystem {
>   	uint32_t inodesz;
>   	/* Sectors per Block */
>   	uint32_t sect_perblk;
> +	/* Group Descriptor size */
> +	uint16_t gdsize;
>   	/* Group Descriptor Block Number */
>   	uint32_t gdtable_blkno;
>   	/* Total block groups of partition */