On 2/18/20 5:02 PM, Matthew Wilcox wrote: > On Tue, Feb 18, 2020 at 04:01:43PM -0800, John Hubbard wrote: >> How about this instead? It uses the "for" loop fully and more naturally, >> and is easier to read. And it does the same thing: >> >> 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); >> >> return page; >> } >> >> static inline struct page *readahead_next(struct readahead_control *rac) >> { >> rac->_nr_pages -= rac->_batch_count; >> rac->_start += rac->_batch_count; >> >> return readahead_page(rac); >> } >> >> #define readahead_for_each(rac, page) \ >> for (page = readahead_page(rac); page != NULL; \ >> page = readahead_page(rac)) > > I'm assuming you mean 'page = readahead_next(rac)' on that second line. > > If you keep reading all the way to the penultimate patch, it won't work > for iomap ... at least not in the same way. >
OK, so after an initial look at patch 18's ("iomap: Convert from readpages to readahead") use of readahead_page() and readahead_next(), I'm not sure what I'm missing. Seems like it would work...? thanks, -- John Hubbard NVIDIA