Date: Thu, 30 Mar 2006 14:30:12 +0200
From: Jens Axboe <axboe@suse.de>
To: Andrew Morton <akpm@osdl.org>
Cc: linux-kernel@vger.kernel.org, torvalds@osdl.org
Subject: Re: [PATCH] splice support #2
Message-ID: <20060330123011.GB13476@suse.de>
References: <20060330100630.GT13476@suse.de> <20060330021644.7f7c5282.akpm@osdl.org> <20060330102419.GU13476@suse.de> <20060330031643.028a28de.akpm@osdl.org> <20060330115525.GV13476@suse.de>
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On Thu, Mar 30 2006, Jens Axboe wrote:
> On Thu, Mar 30 2006, Andrew Morton wrote:
> > Jens Axboe <axboe@suse.de> wrote:
> > >
> > > > > +static void *page_cache_pipe_buf_map(struct file *file,
> > >  > > +				     struct pipe_inode_info *info,
> > >  > > +				     struct pipe_buffer *buf)
> > >  > > +{
> > >  > > +	struct page *page = buf->page;
> > >  > > +
> > >  > > +	lock_page(page);
> > >  > > +
> > >  > > +	if (!PageUptodate(page)) {
> > >  > 
> > >  >  || page->mapping == NULL
> > > 
> > >  Fixed
> > 
> > Actually that wasn't right.  If the page was truncated then we shouldn't
> > return -EIO to userspace.  We should return zero, as this is the first
> > page.
> 
> _if_ this is the first page, then agree.
> 
> > Which means either returning an ERR_PTR here for -EIO or re-checking i_size
> > in the caller.   Maybe the latter?
> 
> The latter sounds better, I'll add that.

Actually that's a little hard, since you don't know what state buf->page
is in - it might be page cache, it might not be. So I opted for the
ERR_PTR approach, just returning -ENODATA on !page->mapping.

-- 
Jens Axboe

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