Re: [PATCH 01/15] ubifs: Set page uptodate in the correct place

Matthew Wilcox
2024-01-22T14:40:33Z

On Mon, Jan 22, 2024 at 03:22:45PM +0800, Zhihao Cheng wrote:
> 在 2024/1/21 7:08, Matthew Wilcox (Oracle) 写道:
> > Page cache reads are lockless, so setting the freshly allocated page
> > uptodate before we've overwritten it with the data it's supposed to have
> > in it will allow a simultaneous reader to see old data. Move the call
> > to SetPageUptodate into ubifs_write_end(), which is after we copied the
> > new data into the page.
>
> This solution looks good to me, and I think 'SetPageUptodate' should be
> removed from write_begin_slow(slow path) too.

I didn't bother because we have just read into the page so it is
uptodate. A racing read will see the data from before the write, but
that's an acceptable ordering of events.