From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0B40C5DF9D for ; Thu, 29 Oct 2020 19:34:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 545D22087D for ; Thu, 29 Oct 2020 19:34:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="cgdijzCx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726581AbgJ2Teb (ORCPT ); Thu, 29 Oct 2020 15:34:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56544 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726212AbgJ2TeL (ORCPT ); Thu, 29 Oct 2020 15:34:11 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D176DC0613D6 for ; Thu, 29 Oct 2020 12:34:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=5Qi+fkVc5y2m3fg4x8n5YvSh2yc6fBKTXrBLflPtfFo=; b=cgdijzCxM0jsbGOUGge5xzXqxe pjiKNnaXc3NeGn6Y9ZsbMPzl3h6AUlFtKDhYbT9JE/1mw4hoEM1yCsMVuIomzvrFZULUGhCwGPmNV HQxBdil412iT477HB03yMlb+wSEuHSMTMiiKKCDai6JexnnPjf0x+pgsEXOtIA3srgZx1gEKOc6Yv xCc4+C3DJQ8MesMu6VHhTLTZ5eTGxroqTX8j3JPz8CHa2aBsSL93VpY7WEmAapLdQO/ilsSonqioq /TFR3xNUasJUuLriGHbkxPKD7ApX71/nzu3DmIIZU87H2xZCjcDti2ZkI7oOVmerilThG4K3G00HL TkNn+MnQ==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kYDgX-0007bn-AZ; Thu, 29 Oct 2020 19:34:09 +0000 From: "Matthew Wilcox (Oracle)" To: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Cc: "Matthew Wilcox (Oracle)" Subject: [PATCH 07/19] mm/filemap: Use head pages in generic_file_buffered_read Date: Thu, 29 Oct 2020 19:33:53 +0000 Message-Id: <20201029193405.29125-8-willy@infradead.org> X-Mailer: git-send-email 2.21.3 In-Reply-To: <20201029193405.29125-1-willy@infradead.org> References: <20201029193405.29125-1-willy@infradead.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Add mapping_get_read_heads() which returns the head pages which represent a contiguous array of bytes in the file. It also stops when encountering a page marked as Readahead or !Uptodate (but does return that page) so it can be handled appropriately by gfbr_get_pages(). Signed-off-by: Matthew Wilcox (Oracle) --- mm/filemap.c | 78 ++++++++++++++++++++++++++++++++++++++++------------ 1 file changed, 61 insertions(+), 17 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index 1bfd87d85bfd..c0161f42f37d 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2166,6 +2166,48 @@ static void shrink_readahead_size_eio(struct file_ra_state *ra) ra->ra_pages /= 4; } +static unsigned mapping_get_read_heads(struct address_space *mapping, + pgoff_t index, unsigned int nr_pages, struct page **pages) +{ + XA_STATE(xas, &mapping->i_pages, index); + struct page *head; + unsigned int ret = 0; + + if (unlikely(!nr_pages)) + return 0; + + rcu_read_lock(); + for (head = xas_load(&xas); head; head = xas_next(&xas)) { + if (xas_retry(&xas, head)) + continue; + if (xa_is_value(head)) + break; + if (!page_cache_get_speculative(head)) + goto retry; + + /* Has the page moved or been split? */ + if (unlikely(head != xas_reload(&xas))) + goto put_page; + + pages[ret++] = head; + if (ret == nr_pages) + break; + if (!PageUptodate(head)) + break; + if (PageReadahead(head)) + break; + xas.xa_index = head->index + thp_nr_pages(head) - 1; + xas.xa_offset = (xas.xa_index >> xas.xa_shift) & XA_CHUNK_MASK; + continue; +put_page: + put_page(head); +retry: + xas_reset(&xas); + } + rcu_read_unlock(); + return ret; +} + static int lock_page_for_iocb(struct kiocb *iocb, struct page *page) { if (iocb->ki_flags & IOCB_WAITQ) @@ -2328,14 +2370,14 @@ static int gfbr_get_pages(struct kiocb *iocb, struct iov_iter *iter, struct file_ra_state *ra = &filp->f_ra; pgoff_t index = iocb->ki_pos >> PAGE_SHIFT; pgoff_t last_index = (iocb->ki_pos + iter->count + PAGE_SIZE-1) >> PAGE_SHIFT; - int i, j, nr_got, err = 0; + int i, nr_got, err = 0; nr = min_t(unsigned long, last_index - index, nr); find_page: if (fatal_signal_pending(current)) return -EINTR; - nr_got = find_get_pages_contig(mapping, index, nr, pages); + nr_got = mapping_get_read_heads(mapping, index, nr, pages); if (nr_got) goto got_pages; @@ -2344,7 +2386,7 @@ static int gfbr_get_pages(struct kiocb *iocb, struct iov_iter *iter, page_cache_sync_readahead(mapping, ra, filp, index, last_index - index); - nr_got = find_get_pages_contig(mapping, index, nr, pages); + nr_got = mapping_get_read_heads(mapping, index, nr, pages); if (nr_got) goto got_pages; @@ -2355,15 +2397,14 @@ static int gfbr_get_pages(struct kiocb *iocb, struct iov_iter *iter, got_pages: for (i = 0; i < nr_got; i++) { struct page *page = pages[i]; - pgoff_t pg_index = index + i; + pgoff_t pg_index = page->index; loff_t pg_pos = max(iocb->ki_pos, (loff_t) pg_index << PAGE_SHIFT); loff_t pg_count = iocb->ki_pos + iter->count - pg_pos; if (PageReadahead(page)) { if (iocb->ki_flags & IOCB_NOIO) { - for (j = i; j < nr_got; j++) - put_page(pages[j]); + put_page(page); nr_got = i; err = -EAGAIN; break; @@ -2375,8 +2416,7 @@ static int gfbr_get_pages(struct kiocb *iocb, struct iov_iter *iter, if (!PageUptodate(page)) { if ((iocb->ki_flags & IOCB_NOWAIT) || ((iocb->ki_flags & IOCB_WAITQ) && i)) { - for (j = i; j < nr_got; j++) - put_page(pages[j]); + put_page(page); nr_got = i; err = -EAGAIN; break; @@ -2385,8 +2425,6 @@ static int gfbr_get_pages(struct kiocb *iocb, struct iov_iter *iter, page = gfbr_update_page(iocb, mapping, iter, page, pg_pos, pg_count); if (IS_ERR_OR_NULL(page)) { - for (j = i + 1; j < nr_got; j++) - put_page(pages[j]); nr_got = i; err = PTR_ERR_OR_ZERO(page); break; @@ -2500,20 +2538,26 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb, mark_page_accessed(pages[i]); for (i = 0; i < pg_nr; i++) { - unsigned int offset = iocb->ki_pos & ~PAGE_MASK; - unsigned int bytes = min_t(loff_t, end_offset - iocb->ki_pos, - PAGE_SIZE - offset); - unsigned int copied; + struct page *page = pages[i]; + size_t page_size = thp_size(page); + size_t offset = iocb->ki_pos & (page_size - 1); + size_t bytes = min_t(loff_t, end_offset - iocb->ki_pos, + page_size - offset); + size_t copied; /* * If users can be writing to this page using arbitrary * virtual addresses, take care about potential aliasing * before reading the page on the kernel side. */ - if (writably_mapped) - flush_dcache_page(pages[i]); + if (writably_mapped) { + int j; + + for (j = 0; j < thp_nr_pages(page); j++) + flush_dcache_page(page + j); + } - copied = copy_page_to_iter(pages[i], offset, bytes, iter); + copied = copy_page_to_iter(page, offset, bytes, iter); written += copied; iocb->ki_pos += copied; -- 2.28.0