lkml.org 
[lkml]   [2023]   [Feb]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: linux-next: manual merge of the mm-stable tree with the cifs tree
On Tue, Feb 21, 2023 at 03:05:26PM +0000, David Howells wrote:
> Matthew Wilcox <willy@infradead.org> wrote:
>
> > > + start = folio_pos(folio); /* May regress with THPs */
> >
> > What does this comment mean?
>
> "start" may end up going backwards if it's pointing to the middle of a folio.

So that's "regress" in the sense of "May point earlier in the file",
rather than "May cause a bug" (which was how I read it)?

> > > + /* At this point we hold neither the i_pages lock nor the
> > > + * page lock: the page may be truncated or invalidated
> > > + * (changing page->mapping to NULL), or even swizzled
> > > + * back from swapper_space to tmpfs file mapping
> >
> > Where does this comment come from? This is cifs, not tmpfs. You'll
> > never be asked to writeback a page from the swap cache. Dirty pages
> > can be truncated, so the first half of the comment is still accurate.
> > I'd rather it moved down to below the folio lock, and was rephrased
> > so it described why we're checking everything again.
>
> I picked it up into afs from somewhere - nfs maybe? The same comment is in
> fs/btrfs/extent_io.c. grep for 'swizzled' in fs/. You modified the comment
> in b93b016313b3ba8003c3b8bb71f569af91f19fc7 in 2018, so it's been around a
> while.

I was just removing references to ->tree_lock ;-)

\
 
 \ /
  Last update: 2023-03-27 00:30    [W:0.262 / U:0.072 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site