On Wednesday, November 16, 2016 12:31 PM Jens Axboe wrote: > @@ -369,10 +369,25 @@ ondemand_readahead(struct address_space *mapping, > bool hit_readahead_marker, pgoff_t offset, > unsigned long req_size) > { > - unsigned long max = ra->ra_pages; > + unsigned long io_pages, max_pages; > pgoff_t prev_offset; > > /* > + * If bdi->io_pages is set, that indicates the (soft) max IO size > + * per command for that device. If we have that available, use > + * that as the max suitable read-ahead size for this IO. Instead of > + * capping read-ahead at ra_pages if req_size is larger, we can go > + * up to io_pages. If io_pages isn't set, fall back to using > + * ra_pages as a safe max. > + */ > + io_pages = inode_to_bdi(mapping->host)->io_pages; > + if (io_pages) { > + max_pages = max_t(unsigned long, ra->ra_pages, req_size); > + io_pages = min(io_pages, max_pages); Doubt if you mean max_pages = min(io_pages, max_pages); > + } else > + max_pages = ra->ra_pages; > + -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>