- /*
- * Reuse buf page, if SPLICE_F_MOVE is set and we are doing a full
- * page.
- */
- if ((sd->flags & SPLICE_F_MOVE) && this_len == PAGE_CACHE_SIZE) {
- /*
- * If steal succeeds, buf->page is now pruned from the
- * pagecache and we can reuse it. The page will also be
- * locked on successful return.
- */
- if (buf->ops->steal(pipe, buf))
- goto find_page;
-
- page = buf->page;
- if (add_to_page_cache(page, mapping, index, gfp_mask)) {
- unlock_page(page);
- goto find_page;
- }
-
- page_cache_get(page);
-
- if (!(buf->flags & PIPE_BUF_FLAG_LRU))
- lru_cache_add(page);
- } else {
-find_page:
- page = find_lock_page(mapping, index);
- if (!page) {
- ret = -ENOMEM;
- page = page_cache_alloc_cold(mapping);
- if (unlikely(!page))
- goto out_nomem;
-
- /*
- * This will also lock the page
- */
- ret = add_to_page_cache_lru(page, mapping, index,
- gfp_mask);
- if (unlikely(ret))
- goto out;
- }
-
- /*
- * We get here with the page locked. If the page is also
- * uptodate, we don't need to do more. If it isn't, we
- * may need to bring it in if we are not going to overwrite
- * the full page.
- */
- if (!PageUptodate(page)) {
- if (this_len < PAGE_CACHE_SIZE) {
- ret = mapping->a_ops->readpage(file, page);
- if (unlikely(ret))
- goto out;
-
- lock_page(page);
-
- if (!PageUptodate(page)) {
- /*
- * Page got invalidated, repeat.
- */
- if (!page->mapping) {
- unlock_page(page);
- page_cache_release(page);
- goto find_page;
- }
- ret = -EIO;
- goto out;
- }
- } else
- SetPageUptodate(page);
- }
- }
-
- ret = mapping->a_ops->prepare_write(file, page, offset, offset+this_len);
- if (unlikely(ret)) {
- loff_t isize = i_size_read(mapping->host);
-
- if (ret != AOP_TRUNCATED_PAGE)
- unlock_page(page);
- page_cache_release(page);
- if (ret == AOP_TRUNCATED_PAGE)
- goto find_page;
-
- /*
- * prepare_write() may have instantiated a few blocks
- * outside i_size. Trim these off again.
- */
- if (sd->pos + this_len > isize)
- vmtruncate(mapping->host, isize);
-