Dave Chinner
2020-Feb-11 04:52 UTC
[Ocfs2-devel] [PATCH v5 04/13] mm: Add readahead address space operation
On Mon, Feb 10, 2020 at 05:03:39PM -0800, Matthew Wilcox wrote:> From: "Matthew Wilcox (Oracle)" <willy at infradead.org> > > This replaces ->readpages with a saner interface: > - Return void instead of an ignored error code. > - Pages are already in the page cache when ->readahead is called. > - Implementation looks up the pages in the page cache instead of > having them passed in a linked list. > > Signed-off-by: Matthew Wilcox (Oracle) <willy at infradead.org>....> > +/* > + * Readahead is of a block of consecutive pages. > + */ > +struct readahead_control { > + struct file *file; > + struct address_space *mapping; > +/* private: use the readahead_* accessors instead */ > + pgoff_t start; > + unsigned int nr_pages; > + unsigned int batch_count; > +}; > + > +static inline struct page *readahead_page(struct readahead_control *rac) > +{ > + struct page *page; > + > + if (!rac->nr_pages) > + return NULL; > + > + page = xa_load(&rac->mapping->i_pages, rac->start); > + VM_BUG_ON_PAGE(!PageLocked(page), page); > + rac->batch_count = hpage_nr_pages(page); > + rac->start += rac->batch_count;There's no mention of large page support in the patch description and I don't recall this sort of large page batching in previous iterations. This seems like new functionality to me, not directly related to the initial ->readahead API change? What have I missed? Cheers, Dave. -- Dave Chinner david at fromorbit.com