[Ocfs2-devel] ocfs2: fix sparse file & data ordering issue in direct io

[Eric Ren]

Hi Dan,

On 11/15/2016 06:36 PM, Dan Carpenter wrote:
> Ryan's email is dead.  But this is buggy.  Someone please fix it.
>
> regards,
> dan carpenter
>
> On Tue, Nov 15, 2016 at 01:33:30PM +0300, Dan Carpenter wrote:
>> I never got a response on this.  I was looking at it today and it still
>> looks buggy to me.
>>
>> regards,
>> dan carpenter
>>
>> On Wed, Mar 09, 2016 at 01:25:05PM +0300, Dan Carpenter wrote:
>>> Hello Ryan Ding,
>>>
>>> The patch fbe25fb91af5: "ocfs2: fix sparse file & data ordering issue
>>> in direct io" from Feb 25, 2016, leads to the following static
>>> checker warning:
>>>
>>> 	fs/ocfs2/aops.c:2242 ocfs2_dio_get_block()
>>> 	error: potentially dereferencing uninitialized 'wc'.
>>>
>>> fs/ocfs2/aops.c
>>>    2235
>>>    2236          ret = ocfs2_write_begin_nolock(inode->i_mapping, pos, len,
>>>    2237                                         OCFS2_WRITE_DIRECT, NULL,
>>>    2238                                         (void **)&wc, di_bh, NULL);
>>>                                                 ^^^^^^^^^^^^
How do you perform the static checker? Please tech me;-)

Regarding this warning, please try to make this line 
(https://github.com/torvalds/linux/blob/master/fs/ocfs2/aops.c#L2128)
into:

struct ocfs2_write_ctxt *wc = NULL;

It should work, and haven't any side effect.

Eric
>>>
>>> See commit 5cffff9e2986 ('ocfs2: Fix ocfs2_page_mkwrite()') for an
>>> explanation why a zero return here does not imply that "wc" has been
>>> initialized.
>>>
>>>    2239          if (ret) {
>>>    2240                  mlog_errno(ret);
>>>    2241                  goto unlock;
>>>    2242          }
>>>    2243
>>>    2244          desc = &wc->w_desc[0];
>>>    2245
>>>    2246          p_blkno = ocfs2_clusters_to_blocks(inode->i_sb, desc->c_phys);
>>>
>>> regards,
>>> dan carpenter
> _______________________________________________
> Ocfs2-devel mailing list
> Ocfs2-devel at oss.oracle.com
> https://oss.oracle.com/mailman/listinfo/ocfs2-devel
>