Re: [RFC][PATCH] vfs: don't fallback to buffered read if the offset of dio read is beyond eof

[Zheng Liu <gnehzuil.liu@gmail.com>]

Hi Jan,

On Thu, Nov 28, 2013 at 12:03:59AM +0100, Jan Kara wrote:
[...]
> > This commit let dio read return directly if the current offset of the
> > dio read is beyond the end of file in order to avoid this problem.
>   This would be OK as well but it doesn't solve the case when the reader
> uses a normal buffered read, does it?

Yup, it doesn't fix that case with buffered read because as Dave's
comment we shouldn't need to ensure that.  So in this commit I just try
to fix the dio case.

> So I think trimming read count as I
> described as a reply to your previous patch might be still better.

I have seen your reply.  Thanks for your suggestion, and I will give it
a try.

                                                - Zheng

> 
> 								Honza
> 
> > 
> > Cc: Alexander Viro <viro@zeniv.linux.org.uk>
> > Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
> > ---
> >  mm/filemap.c |    2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/mm/filemap.c b/mm/filemap.c
> > index 1e6aec4..4179249 100644
> > --- a/mm/filemap.c
> > +++ b/mm/filemap.c
> > @@ -1452,6 +1452,8 @@ generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
> >  				file_accessed(filp);
> >  				goto out;
> >  			}
> > +		} else {
> > +			goto out;
> >  		}
> >  	}
> >  
> > -- 
> > 1.7.9.7
> > 
> > --
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> -- 
> Jan Kara <jack@suse.cz>
> SUSE Labs, CR