Re: eCryptfs: Request for review

[Badari Pulavarty <pbadari@gmail.com>]

On Wed, 2005-10-19 at 14:55 -0500, Michael Thompson wrote:
> 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 is telling you that there is already IO in progress on that page.
Either you ended up in  __block_write_full_page() twice or called
__block_write_full_page() before finishing up end_page_writeback().

Thanks,
Badari