This patch implements setattr fileop for Tux3.  Tux3 now stores the

mtime properly and persistently, which I tested under UML.
I'm updating the MTIME_BIT in tuxnode->present every time, before

calling inode_setattr, which marks the inode dirty.  I considered

twiddling the MTIME_BIT afterwards, but I wasn't sure if that was safe

since the inode was already set dirty (and could possibly get

flushed?), so I was forced to check if the mtime/ctime was changing.
Thanks to Daniel for the excellent instructions:

http://mailman.tux3.org/pipermail/tux3/2008-November/000380.html

Now we just need a git repo that works :)
diff -rup linux-2.6.26.5.orig/fs/tux3/inode.c linux-2.6.26.5/fs/tux3/inode.c

--- linux-2.6.26.5.orig/fs/tux3/inode.c 2008-12-11 17:42:16.000000000 -0800

+++ linux-2.6.26.5/fs/tux3/inode.c      2008-12-11 17:50:29.000000000 -0800

@@ -218,7 +218,7 @@ static const struct file_operations tux_

 static const struct inode_operations tux_file_iops = {

 //     .truncate       = ext4_truncate,

 //     .permission     = ext4_permission,

-//     .setattr        = ext4_setattr,

+       .setattr        = tux3_setattr,

 //     .getattr        = ext4_getattr

 #ifdef CONFIG_EXT4DEV_FS_XATTR

 //     .setxattr       = generic_setxattr,

@@ -324,4 +324,22 @@ struct inode *tux3_iget(struct super_blo

        unlock_new_inode(inode);

        return inode;

 }

+

+int tux3_setattr(struct dentry *dentry, struct iattr *iattr)

+{

+       struct inode *inode = dentry->d_inode;

+       tuxnode_t *tuxnode = tux_inode(inode);

+       int error;

+

+       error = inode_change_ok(inode, iattr);

+       if (error)

+               return error;

+       if (timespec_equal(iattr->ia_valid & ATTR_MTIME ?

&iattr->ia_mtime : &inode->i_mtime,

+                          iattr->ia_valid & ATTR_CTIME ?

&iattr->ia_ctime : &inode->i_ctime))

+               tuxnode->present &= ~MTIME_BIT;

+       else

+               tuxnode->present |= MTIME_BIT;

+

+       return inode_setattr(inode, iattr);

+}

 #endif /* !__KERNEL__ */

diff -rup linux-2.6.26.5.orig/fs/tux3/tux3.h linux-2.6.26.5/fs/tux3/tux3.h

--- linux-2.6.26.5.orig/fs/tux3/tux3.h  2008-12-11 17:42:16.000000000 -0800

+++ linux-2.6.26.5/fs/tux3/tux3.h       2008-12-11 17:36:37.000000000 -0800

@@ -636,6 +636,7 @@ void tux3_clear_inode(struct inode *inod

 int tux3_write_inode(struct inode *inode, int do_sync);

 struct inode *tux_create_inode(struct inode *dir, int mode);

 struct inode *tux3_iget(struct super_block *sb, inum_t inum);

+int tux3_setattr(struct dentry *dentry, struct iattr *iattr);
 /* xattr.c */

 int xcache_dump(struct inode *inode);