BUG at mm/filemap.c:1749 (2.6.24, jffs2, unionfs)

[Erez Zadok]

In message <200710191716.53470.nickpiggin at yahoo.com.au>, Nick Piggin writes:
[...]
> Hmm, looks like jffs2_write_end is writing more than we actually ask it
> to, and returns that back.
> 
>         unsigned aligned_start = start & ~3;
> 
> and
> 
>         if (end == PAGE_CACHE_SIZE) {
>                 /* When writing out the end of a page, write out the
>                    _whole_ page. This helps to reduce the number of
>                    nodes in files which have many short writes, like
>                    syslog files. */
>                 start = aligned_start = 0;
>         }
> 
> These "longer" writes are fine, but they shouldn't get propagated back
> to the vm/vfs. Something like the following patch might fix it.
> 
> 
> --Boundary-00=_lnFGHwOggSRGKPd
> Content-Type: text/x-diff;
>   charset="utf-8";
>   name="jffs2-writtenlen-fix.patch"
> Content-Transfer-Encoding: 7bit
> Content-Disposition: attachment;
> 	filename="jffs2-writtenlen-fix.patch"

Nick, the patch worked.  All of my unionfs-over-jffs2 tests passed.

Thanks,
Erez.