On Tue, 2005-08-23 at 21:00 +0900, KaiGai Kohei wrote:
> Hello,
>
> In recent days, I'm interrested in XATTR support in JFFS2.
>
> I have started a discussion about it on MTD-ML.
> http://lists.infradead.org/pipermail/linux-mtd/2005-August/013415.html
>
> By ML-archive, an implementation use hidden-file to store XATTR was
> rejected finally. Thus, I adopted different approach.
> This implementation added two new node types JFFS2_NODETYPE_XATTR
> and JFFS2_NODETYPE_XREF for XATTR representation.
>
> If your comment can be gotten, I'm so glad.
>
> # I think it's not appropriate to discuss JFFS2 at SELinux-ML.
> # Please comment it on MTD-ML, if possible.
>
> Thanks,
>
> *---- Example of use ------------
>
> In my desktop PC, "fs_use_xattr jffs2 system_u:object_r:fs_t;"
> was configured. :)
>
> [root@saba ~]# dd if=jffs2.xattr.img of=/dev/mtdblock0
> 8192+0 records in
> 8192+0 records out
> [root@saba ~]# mount -t jffs2 /dev/mtdblock0 /mnt/0
> [root@saba ~]# ls -lZ /mnt/0
> drwxr-xr-x root root system_u:object_r:bin_t bin/
> drwxr-xr-x root root system_u:object_r:mnt_t dev/
> drwxr-xr-x root root system_u:object_r:etc_t etc/
> -rw-r--r-- root root system_u:object_r:mnt_t hoge
> -rwxr-xr-x root root system_u:object_r:mnt_t init*
> drwxr-xr-x root root system_u:object_r:lib_t lib/
> drwxr-xr-x root root system_u:object_r:mnt_t loopfs/
> drwxr-xr-x root root system_u:object_r:mnt_t proc/
> lrwxrwxrwx root root system_u:object_r:bin_t sbin
> drwxr-xr-x root root system_u:object_r:mnt_t sys/
> drwxr-xr-x root root system_u:object_r:mnt_t sysroot/
> [root@saba ~]#

Thanks for working on this functionality. From a very brief look at the patch, one question I had was whether you could be using the generic xattr methods introduced by James Morris' earlier xattr code consolidation patches that are now in the mainline kernel. See the generic_* functions in fs/xattr.c and how they are used by the fs code (e.g. look at the ext3 xattr implementation). Per recent discussions on linux-fsdevel, using those helpers is the preferred approach for the future. You can then just set sb->s_xattr for the specific handlers in jffs2, e.g. see the ext3 code for an example.

Might be worth mentioning this work on acl-devel as well, although you don't yet support ACLs or other xattrs. But I'm sure Andreas Gruenbacher would be interested, as he did the original xattr and ACL development work for ext[23], and he may be able to give feedback on your approach to various aspects like the attribute caching.

-- 
Stephen Smalley
National Security Agency


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