What __generic_file_splice_read() does is get a series of uptodate pages and put them into the pipe buffer.
The get_page_for_read() helper can now be used to get the pages, simplifying the code and making sure the splice(2) stays in sync with read(2). For example get_page_for_read() can handle partially uptodate pages and now splice can take advantage of these as well. Signed-off-by: Miklos Szeredi <[email protected]> --- fs/splice.c | 169 +++++------------------------------------------------------- 1 file changed, 12 insertions(+), 157 deletions(-) diff --git a/fs/splice.c b/fs/splice.c index dc4648ba6e8d..e7757b363b6c 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -265,14 +265,12 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, struct pipe_inode_info *pipe, size_t len, unsigned int flags) { - struct address_space *mapping = in->f_mapping; unsigned int loff, nr_pages, req_pages; struct page *pages[PIPE_DEF_BUFFERS]; struct partial_page partial[PIPE_DEF_BUFFERS]; struct page *page; - pgoff_t index, end_index; - loff_t isize; - int error, page_nr; + pgoff_t index; + int error; struct splice_pipe_desc spd = { .pages = pages, .partial = partial, @@ -290,168 +288,25 @@ __generic_file_splice_read(struct file *in, loff_t *ppos, req_pages = (len + loff + PAGE_SIZE - 1) >> PAGE_SHIFT; nr_pages = min(req_pages, spd.nr_pages_max); - /* - * Lookup the (hopefully) full range of pages we need. - */ - spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, spd.pages); - index += spd.nr_pages; - - /* - * If find_get_pages_contig() returned fewer pages than we needed, - * readahead/allocate the rest and fill in the holes. - */ - if (spd.nr_pages < nr_pages) - page_cache_sync_readahead(mapping, &in->f_ra, in, - index, req_pages - spd.nr_pages); - error = 0; - while (spd.nr_pages < nr_pages) { - /* - * Page could be there, find_get_pages_contig() breaks on - * the first hole. - */ - page = find_get_page(mapping, index); - if (!page) { - /* - * page didn't exist, allocate one. - */ - page = page_cache_alloc_cold(mapping); - if (!page) - break; + while (spd.nr_pages < nr_pages && len) { + long ret; - error = add_to_page_cache_lru(page, mapping, index, - mapping_gfp_constraint(mapping, GFP_KERNEL)); - if (unlikely(error)) { - put_page(page); - if (error == -EEXIST) - continue; - break; - } - /* - * add_to_page_cache() locks the page, unlock it - * to avoid convoluting the logic below even more. - */ - unlock_page(page); - } - - spd.pages[spd.nr_pages++] = page; - index++; - } - - /* - * Now loop over the map and see if we need to start IO on any - * pages, fill in the partial map, etc. - */ - index = *ppos >> PAGE_SHIFT; - nr_pages = spd.nr_pages; - spd.nr_pages = 0; - for (page_nr = 0; page_nr < nr_pages; page_nr++) { - unsigned int this_len; - - if (!len) + ret = get_page_for_read(in, loff, len, index, &page); + if (ret <= 0) { + error = ret; break; - - /* - * this_len is the max we'll use from this page - */ - this_len = min_t(unsigned long, len, PAGE_SIZE - loff); - page = spd.pages[page_nr]; - - if (PageReadahead(page)) - page_cache_async_readahead(mapping, &in->f_ra, in, - page, index, req_pages - page_nr); - - /* - * If the page isn't uptodate, we may need to start io on it - */ - if (!PageUptodate(page)) { - lock_page(page); - - /* - * Page was truncated, or invalidated by the - * filesystem. Redo the find/create, but this time the - * page is kept locked, so there's no chance of another - * race with truncate/invalidate. - */ - if (!page->mapping) { - unlock_page(page); -retry_lookup: - page = find_or_create_page(mapping, index, - mapping_gfp_mask(mapping)); - - if (!page) { - error = -ENOMEM; - break; - } - put_page(spd.pages[page_nr]); - spd.pages[page_nr] = page; - } - /* - * page was already under io and is now done, great - */ - if (PageUptodate(page)) { - unlock_page(page); - goto fill_it; - } - - /* - * need to read in the page - */ - error = mapping->a_ops->readpage(in, page); - if (unlikely(error)) { - /* - * Re-lookup the page - */ - if (error == AOP_TRUNCATED_PAGE) - goto retry_lookup; - - break; - } - } -fill_it: - /* - * i_size must be checked after PageUptodate. - */ - isize = i_size_read(mapping->host); - end_index = (isize - 1) >> PAGE_SHIFT; - if (unlikely(!isize || index > end_index)) - break; - - /* - * if this is the last page, see if we need to shrink - * the length and stop - */ - if (end_index == index) { - unsigned int plen; - - /* - * max good bytes in this page - */ - plen = ((isize - 1) & ~PAGE_MASK) + 1; - if (plen <= loff) - break; - - /* - * force quit after adding this page - */ - this_len = min(this_len, plen - loff); - len = this_len; } - spd.partial[page_nr].offset = loff; - spd.partial[page_nr].len = this_len; - len -= this_len; - loff = 0; + spd.pages[spd.nr_pages] = page; + spd.partial[spd.nr_pages].offset = loff; + spd.partial[spd.nr_pages].len = ret; spd.nr_pages++; index++; + len -= ret; + loff = 0; } - /* - * Release any pages at the end, if we quit early. 'page_nr' is how far - * we got, 'nr_pages' is how many pages are in the map. - */ - while (page_nr < nr_pages) - put_page(spd.pages[page_nr++]); in->f_ra.prev_pos = (loff_t)index << PAGE_SHIFT; if (spd.nr_pages) -- 2.5.5
