On Tue, Jan 14, 2020 at 06:38:40PM -0800, Matthew Wilcox wrote:
> static loff_t
> +iomap_readahead_actor(struct inode *inode, loff_t pos, loff_t length,
> void *data, struct iomap *iomap, struct iomap *srcmap)
> {
> struct iomap_readpage_ctx *ctx = data;
> @@ -410,10 +381,8 @@ iomap_readpages_actor(struct inode *inode, loff_t pos, loff_t length,
> ctx->cur_page = NULL;
> }
> if (!ctx->cur_page) {
> - ctx->cur_page = iomap_next_page(inode, ctx->pages,
> - pos, length, &done);
> - if (!ctx->cur_page)
> - break;
> + ctx->cur_page = readahead_page(inode->i_mapping,
> + pos / PAGE_SIZE);
Don't we at least need a sanity check for a NULL cur_page here?
Also the readahead_page version in your previous patch seems to expect
a byte offset, so the division above would not be required. (and should
probably be replaced with a right shift anyway no matter where it ends
up)
> +unsigned
> +iomap_readahead(struct address_space *mapping, pgoff_t start,
> unsigned nr_pages, const struct iomap_ops *ops)
> {
> struct iomap_readpage_ctx ctx = {
> - .pages = pages,
> .is_readahead = true,
> };
> - loff_t pos = page_offset(list_entry(pages->prev, struct page, lru));
> - loff_t last = page_offset(list_entry(pages->next, struct page, lru));
> - loff_t length = last - pos + PAGE_SIZE, ret = 0;
> + loff_t pos = start * PAGE_SIZE;
> + loff_t length = nr_pages * PAGE_SIZE;
Any good reason not to pass byte offsets for start and length?
> + return length / PAGE_SIZE;
Same for the return value?
For the file systems that would usually be a more natural interface than
a page index and number of pages.
