From 82c156f853840645604acd7c2cebcb75ed1b6652 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 22 Sep 2016 23:35:42 -0400 Subject: switch generic_file_splice_read() to use of ->read_iter() ... and kill the ->splice_read() instances that can be switched to it Signed-off-by: Al Viro --- fs/splice.c | 244 +++++++----------------------------------------------------- 1 file changed, 28 insertions(+), 216 deletions(-) (limited to 'fs/splice.c') diff --git a/fs/splice.c b/fs/splice.c index 589a1d52bb98..58c322a87f44 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -281,207 +281,6 @@ void splice_shrink_spd(struct splice_pipe_desc *spd) kfree(spd->partial); } -static int -__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; - struct splice_pipe_desc spd = { - .pages = pages, - .partial = partial, - .nr_pages_max = PIPE_DEF_BUFFERS, - .flags = flags, - .ops = &page_cache_pipe_buf_ops, - .spd_release = spd_release_page, - }; - - if (splice_grow_spd(pipe, &spd)) - return -ENOMEM; - - index = *ppos >> PAGE_SHIFT; - loff = *ppos & ~PAGE_MASK; - 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; - - 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) - 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.nr_pages++; - index++; - } - - /* - * 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) - error = splice_to_pipe(pipe, &spd); - - splice_shrink_spd(&spd); - return error; -} - /** * generic_file_splice_read - splice data from file to a pipe * @in: file to splice from @@ -492,32 +291,46 @@ fill_it: * * Description: * Will read pages from given file and fill them into a pipe. Can be - * used as long as the address_space operations for the source implements - * a readpage() hook. + * used as long as it has more or less sane ->read_iter(). * */ ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, struct pipe_inode_info *pipe, size_t len, unsigned int flags) { - loff_t isize, left; - int ret; - - if (IS_DAX(in->f_mapping->host)) - return default_file_splice_read(in, ppos, pipe, len, flags); + struct iov_iter to; + struct kiocb kiocb; + loff_t isize; + int idx, ret; isize = i_size_read(in->f_mapping->host); if (unlikely(*ppos >= isize)) return 0; - left = isize - *ppos; - if (unlikely(left < len)) - len = left; - - ret = __generic_file_splice_read(in, ppos, pipe, len, flags); + iov_iter_pipe(&to, ITER_PIPE | READ, pipe, len); + idx = to.idx; + init_sync_kiocb(&kiocb, in); + kiocb.ki_pos = *ppos; + ret = in->f_op->read_iter(&kiocb, &to); if (ret > 0) { - *ppos += ret; + *ppos = kiocb.ki_pos; file_accessed(in); + } else if (ret < 0) { + if (WARN_ON(to.idx != idx || to.iov_offset)) { + /* + * a bogus ->read_iter() has copied something and still + * returned an error instead of a short read. + */ + to.idx = idx; + to.iov_offset = 0; + iov_iter_advance(&to, 0); /* to free what was emitted */ + } + /* + * callers of ->splice_read() expect -EAGAIN on + * "can't put anything in there", rather than -EFAULT. + */ + if (ret == -EFAULT) + ret = -EAGAIN; } return ret; @@ -580,7 +393,7 @@ ssize_t kernel_write(struct file *file, const char *buf, size_t count, } EXPORT_SYMBOL(kernel_write); -ssize_t default_file_splice_read(struct file *in, loff_t *ppos, +static ssize_t default_file_splice_read(struct file *in, loff_t *ppos, struct pipe_inode_info *pipe, size_t len, unsigned int flags) { @@ -675,7 +488,6 @@ err: res = error; goto shrink_ret; } -EXPORT_SYMBOL(default_file_splice_read); /* * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' -- cgit v1.2.3-59-g8ed1b