Re: eCryptfs: Request for review

[Michael Thompson <michael.craig.thompson@gmail.com>]

On 10/19/05, Charles P. Wright <cwright@cs.sunysb.edu> wrote:
> The reference count of an eCryptfs dentry may not be the same as the
> reference count of the lower-level dentry.  If the eCryptfs dentry hits
> zero, but the lower-level dentry does not, you are going to remove the
> lower-level dentry from the name space prematurely.
>
> This manifested itself on Unionfs running over squashfs.
I C, if you will. Now that I know, consider it removed :)

> > > In ecryptfs_llseek,  If you are adding pages for extra information, you
> > > need to convert the offset to a lower-level offset, and then convert the
> > > return back to what user space expects it to be.  You should test fsx on
> > > your file system, to sort these types of things out.
> > I believe that this is working, we have run fsx "succesfully" for
> > 10000 iterations. However, its not a total success because we are
> > bugging out in fs/buffer.c:1822 BUG_ON(PageWriteback(page));
> > Will look a bit more closely though.
> Actually nevermind, you are using generic_file_llseek on your own file
> instead of passing the operation down.  That should be fine and dandy
> for files, but I don't know if you are going to have problems with
> directories.
Guess I'll have to test a bit more then... *marks on the TODO*.

Would you like to take a stab at why we are hitting the
fs/buffer.c:1822 BUG_ON(PageWriteback(page)); problem?
I'm pretty much at a loss, although, I will be honest, I haven't
looked into it very much
(it's scary).

Thanks for the help,
Mike