Hi,
On Sun, 02 May 2010 00:18:26 +0900, Jiro SEKIBA <jir@xxxxxxxxx> wrote:
> Hi,
>
> This is an RFC patch to enlarge s_volume_name member of nilfs_super_block.
>
> Current s_volume_name has 16 bytes, which is too small as modern filesystem.
>
> s_last_mounted resides just after s_volume_name and has 64 bytes.
>
> s_last_mounted is historically came from ext2, but not used in nilfs2 at all.
> Deleting s_last_mounted member and merging that space with s_volume_name
> enlarge s_volume_name upto 80 bytes for volume label.
>
> When user land tools see the old header for new disk, it will just ignore
> additional bytes stored in s_last_mounted. While, old disk format has only
> 16 bytes label, it doesn't affects in case seeing the new header for old disk.
>
> Signed-off-by: Jiro SEKIBA <jir@xxxxxxxxx>
Thank you for the proposal.
You're right. The current s_volume_name/s_last_mounted are mimics of
ext2/ext3, and looking back today, the 16 bytes volume name looks a
bit short.
Appending the region reserved for s_last_mounted to s_volume_name is
quite a nice idea!
I confirmed that this simple patch doesn't sacrifice compatibility.
This should be incorporated while we can.
BTW, the patch hit a style issue that I recently fixed with the patch
titled "nilfs2: fix style problems in nilfs2_fs.h":
$ scripts/checkpatch.pl --file include/linux/nilfs2_fs.h
WARNING: please, no space before tabs
#210: FILE: linux/nilfs2_fs.h:210:
+^Ichar^Is_volume_name[80]; ^I/* volume name */$
Could you rewrite it for the for-next branch of nilfs2.git?
You can also remove ``RFC'' from the changelog next time.
Thank you in advance,
Ryusuke Konishi
> ---
> include/linux/nilfs2_fs.h | 3 +--
> 1 files changed, 1 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/nilfs2_fs.h b/include/linux/nilfs2_fs.h
> index 640702e..a41931d 100644
> --- a/include/linux/nilfs2_fs.h
> +++ b/include/linux/nilfs2_fs.h
> @@ -207,8 +207,7 @@ struct nilfs_super_block {
> __le16 s_segment_usage_size; /* Size of a segment usage */
>
> __u8 s_uuid[16]; /* 128-bit uuid for volume */
> - char s_volume_name[16]; /* volume name */
> - char s_last_mounted[64]; /* directory where last mounted */
> + char s_volume_name[80]; /* volume name */
>
> __le32 s_c_interval; /* Commit interval of segment */
> __le32 s_c_block_max; /* Threshold of data amount for
> --
> 1.5.6.5
>
>
>
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