Re: [PATCH v2 09/25] fs: Add a filesystem flag for large pages

[Matthew Wilcox]

On Tue, Feb 11, 2020 at 11:43:18PM -0800, Christoph Hellwig wrote:
> On Tue, Feb 11, 2020 at 08:18:29PM -0800, Matthew Wilcox wrote:
> > From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
> > 
> > The page cache needs to know whether the filesystem supports pages >
> > PAGE_SIZE.
> 
> Does it make sense to set this flag on the file_system_type, which
> is rather broad scope, or a specific superblock or even inode?
> 
> For some file systems we might require on-disk flags that aren't set
> for all instances.

I don't see why we'd need on-disk flags or need to control this on a
per-inode or per-sb basis.  My intent for this flag is to represent
whether the filesystem understands large pages; how the file is cached
should make no difference to the on-disk layout.