Re: v4.4-rc4 regression with direct-io

Jan Kara
2015-12-09T12:07:39Z

On Tue 08-12-15 21:51:09, Al Viro wrote:
> On Tue, Dec 08, 2015 at 02:39:02PM -0700, Ross Zwisler wrote:
> > Hey Jan,
> >
> > In my test setup this commit:
> >
> > 74cedf9b6c60 ("direct-io: Fix negative return from dio read beyond eof")
> >
> > causes a regression with XFS and the test generic/113. The test used to
> > pass, but with the above mentioned commit it just hangs indefinitely.
> >
> > This commit went in between v4.4-rc3 and v4.4-rc4, and it looks like it was
> > marked for stable?
>
> See the tip of vfs.git#for-linus for fix...

Ah, thanks for fixing this up! I'm just wondering how the test program I
was using could have passed because pread() I'm doing there must have
returned ENOMEM... Argh, I see. I have tested the problem with ext4 which
uses DIO_LOCKING mode and in that case 'retval' gets overwritten to 0 by
filemap_write_and_wait() call :-|.

Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR