Ocfs2 devel - Nov 2016 - ocfs2: fix sparse file & data ordering issue in direct io

Hi,

On 11/16/2016 06:45 PM, Dan Carpenter wrote:
> On Wed, Nov 16, 2016 at 10:33:49AM +0800, Eric Ren wrote:
> That silences the warning, of course, but I feel like the code is buggy.
> How do we know that we don't hit that exit path?
Sorry, I missed your point. Do you mean the below?

"1817 goto out_quota; " will free (*wc), but with "ret = 0".
Thus, the caller
think it's OK to use (*wc), but...

Do I understand you correctly?

Eric
>
> fs/ocfs2/aops.c
>    1808          /*
>    1809           * ocfs2_grab_pages_for_write() returns -EAGAIN if it
could not lock
>    1810           * the target page. In this case, we exit with no error
and no target
>    1811           * page. This will trigger the caller, page_mkwrite(), to
re-try
>    1812           * the operation.
>    1813           */
>    1814          if (ret == -EAGAIN) {
>    1815                  BUG_ON(wc->w_target_page);
>    1816                  ret = 0;
>    1817                  goto out_quota;
>    1818          }
>
> regards,
> dan carpenter
>
>
>

On Thu, Nov 17, 2016 at 11:08:08AM +0800, Eric Ren
wrote:
> Hi,
> 
> On 11/16/2016 06:45 PM, Dan Carpenter wrote:
> >On Wed, Nov 16, 2016 at 10:33:49AM +0800, Eric Ren wrote:
> >That silences the warning, of course, but I feel like the code is
buggy.
> >How do we know that we don't hit that exit path?
> Sorry, I missed your point. Do you mean the below?
> 
> "1817 goto out_quota; " will free (*wc), but with "ret =
0". Thus, the caller
> think it's OK to use (*wc), but...
> 
> Do I understand you correctly?
> 
It doesn't free it.  It frees "wc" but not "*fsdata". 
So it leaves it
unintialized on that path.  That's the issue, yes.

It could be that it's impossible to reach that path from here, but it's
not clear to me.

regards,
dan carpenter