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=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 738CEC433DF for ; Tue, 2 Jun 2020 04:46:14 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 29B68206C3 for ; Tue, 2 Jun 2020 04:46:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="Rb8cpJCl" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 29B68206C3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BF32A280003; Tue, 2 Jun 2020 00:46:13 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BCA5F80007; Tue, 2 Jun 2020 00:46:13 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AB8C280014; Tue, 2 Jun 2020 00:46:13 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0216.hostedemail.com [216.40.44.216]) by kanga.kvack.org (Postfix) with ESMTP id 91A7080007 for ; Tue, 2 Jun 2020 00:46:13 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 5CF698248D7C for ; Tue, 2 Jun 2020 04:46:13 +0000 (UTC) X-FDA: 76883035026.25.glove96_19270c0fe8350 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin25.hostedemail.com (Postfix) with ESMTP id 308781804E3A0 for ; Tue, 2 Jun 2020 04:46:13 +0000 (UTC) X-HE-Tag: glove96_19270c0fe8350 X-Filterd-Recvd-Size: 8196 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf14.hostedemail.com (Postfix) with ESMTP for ; Tue, 2 Jun 2020 04:46:12 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5AE7220734; Tue, 2 Jun 2020 04:46:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591073172; bh=K0xoeQE+/Uv2SSFZR+sy+f8z90iA1LqXuzX6aWY0/08=; h=Date:From:To:Subject:In-Reply-To:From; b=Rb8cpJClxfMpvVYyqmBGlUWdbSQkILXHuSZFETjYVIflkQ25/j4p4AefrM1fCLPCm tMrLW9zyY7gj6nVJQBXJO8vwiBOoGhYa1VQX0HIKKzfX+Ll53r/3foQ0TbvN5xREec QEF707K2mei1R0QzT9LUzmWtJrzOMFgkoSgNz2UA= Date: Mon, 01 Jun 2020 21:46:10 -0700 From: Andrew Morton To: akpm@linux-foundation.org, darrick.wong@oracle.com, dchinner@redhat.com, ebiggers@google.com, gaoxiang25@huawei.com, hch@lst.de, jaegeuk@kernel.org, jhubbard@nvidia.com, johannes.thumshirn@wdc.com, joseph.qi@linux.alibaba.com, junxiao.bi@oracle.com, linux-mm@kvack.org, mhocko@suse.com, mm-commits@vger.kernel.org, mszeredi@redhat.com, torvalds@linux-foundation.org, william.kucharski@oracle.com, willy@infradead.org, xiyou.wangcong@gmail.com, yuchao0@huawei.com, ziy@nvidia.com Subject: [patch 015/128] mm: return void from various readahead functions Message-ID: <20200602044610.WBiSUDKyi%akpm@linux-foundation.org> In-Reply-To: <20200601214457.919c35648e96a2b46b573fe1@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Queue-Id: 308781804E3A0 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam04 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: "Matthew Wilcox (Oracle)" Subject: mm: return void from various readahead functions ondemand_readahead has two callers, neither of which use the return value. That means that both ra_submit and __do_page_cache_readahead() can return void, and we don't need to worry that a present page in the readahead window causes us to return a smaller nr_pages than we ought to have. Similarly, no caller uses the return value from force_page_cache_readahead(). Link: http://lkml.kernel.org/r/20200414150233.24495-3-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Dave Chinner Reviewed-by: John Hubbard Reviewed-by: Christoph Hellwig Reviewed-by: William Kucharski Cc: Chao Yu Cc: Cong Wang Cc: Darrick J. Wong Cc: Eric Biggers Cc: Gao Xiang Cc: Jaegeuk Kim Cc: Joseph Qi Cc: Junxiao Bi Cc: Michal Hocko Cc: Zi Yan Cc: Johannes Thumshirn Cc: Miklos Szeredi Signed-off-by: Andrew Morton --- mm/fadvise.c | 4 ---- mm/internal.h | 12 ++++++------ mm/readahead.c | 31 +++++++++++++------------------ 3 files changed, 19 insertions(+), 28 deletions(-) --- a/mm/fadvise.c~mm-return-void-from-various-readahead-functions +++ a/mm/fadvise.c @@ -104,10 +104,6 @@ int generic_fadvise(struct file *file, l if (!nrpages) nrpages = ~0UL; - /* - * Ignore return value because fadvise() shall return - * success even if filesystem can't retrieve a hint, - */ force_page_cache_readahead(mapping, file, start_index, nrpages); break; case POSIX_FADV_NOREUSE: --- a/mm/internal.h~mm-return-void-from-various-readahead-functions +++ a/mm/internal.h @@ -49,20 +49,20 @@ void unmap_page_range(struct mmu_gather unsigned long addr, unsigned long end, struct zap_details *details); -int force_page_cache_readahead(struct address_space *, struct file *, +void force_page_cache_readahead(struct address_space *, struct file *, pgoff_t index, unsigned long nr_to_read); -extern unsigned int __do_page_cache_readahead(struct address_space *mapping, - struct file *filp, pgoff_t offset, unsigned long nr_to_read, +void __do_page_cache_readahead(struct address_space *, struct file *, + pgoff_t index, unsigned long nr_to_read, unsigned long lookahead_size); /* * Submit IO for the read-ahead request in file_ra_state. */ -static inline unsigned long ra_submit(struct file_ra_state *ra, +static inline void ra_submit(struct file_ra_state *ra, struct address_space *mapping, struct file *filp) { - return __do_page_cache_readahead(mapping, filp, - ra->start, ra->size, ra->async_size); + __do_page_cache_readahead(mapping, filp, + ra->start, ra->size, ra->async_size); } /** --- a/mm/readahead.c~mm-return-void-from-various-readahead-functions +++ a/mm/readahead.c @@ -149,10 +149,8 @@ out: * the pages first, then submits them for I/O. This avoids the very bad * behaviour which would occur if page allocations are causing VM writeback. * We really don't want to intermingle reads and writes like that. - * - * Returns the number of pages requested, or the maximum amount of I/O allowed. */ -unsigned int __do_page_cache_readahead(struct address_space *mapping, +void __do_page_cache_readahead(struct address_space *mapping, struct file *filp, pgoff_t offset, unsigned long nr_to_read, unsigned long lookahead_size) { @@ -166,7 +164,7 @@ unsigned int __do_page_cache_readahead(s gfp_t gfp_mask = readahead_gfp_mask(mapping); if (isize == 0) - goto out; + return; end_index = ((isize - 1) >> PAGE_SHIFT); @@ -211,23 +209,21 @@ unsigned int __do_page_cache_readahead(s if (nr_pages) read_pages(mapping, filp, &page_pool, nr_pages, gfp_mask); BUG_ON(!list_empty(&page_pool)); -out: - return nr_pages; } /* * Chunk the readahead into 2 megabyte units, so that we don't pin too much * memory at once. */ -int force_page_cache_readahead(struct address_space *mapping, struct file *filp, - pgoff_t offset, unsigned long nr_to_read) +void force_page_cache_readahead(struct address_space *mapping, + struct file *filp, pgoff_t offset, unsigned long nr_to_read) { struct backing_dev_info *bdi = inode_to_bdi(mapping->host); struct file_ra_state *ra = &filp->f_ra; unsigned long max_pages; if (unlikely(!mapping->a_ops->readpage && !mapping->a_ops->readpages)) - return -EINVAL; + return; /* * If the request exceeds the readahead window, allow the read to @@ -245,7 +241,6 @@ int force_page_cache_readahead(struct ad offset += this_chunk; nr_to_read -= this_chunk; } - return 0; } /* @@ -378,11 +373,10 @@ static int try_context_readahead(struct /* * A minimal readahead algorithm for trivial sequential/random reads. */ -static unsigned long -ondemand_readahead(struct address_space *mapping, - struct file_ra_state *ra, struct file *filp, - bool hit_readahead_marker, pgoff_t offset, - unsigned long req_size) +static void ondemand_readahead(struct address_space *mapping, + struct file_ra_state *ra, struct file *filp, + bool hit_readahead_marker, pgoff_t offset, + unsigned long req_size) { struct backing_dev_info *bdi = inode_to_bdi(mapping->host); unsigned long max_pages = ra->ra_pages; @@ -428,7 +422,7 @@ ondemand_readahead(struct address_space rcu_read_unlock(); if (!start || start - offset > max_pages) - return 0; + return; ra->start = start; ra->size = start - offset; /* old async_size */ @@ -464,7 +458,8 @@ ondemand_readahead(struct address_space * standalone, small random read * Read as is, and do not pollute the readahead state. */ - return __do_page_cache_readahead(mapping, filp, offset, req_size, 0); + __do_page_cache_readahead(mapping, filp, offset, req_size, 0); + return; initial_readahead: ra->start = offset; @@ -489,7 +484,7 @@ readit: } } - return ra_submit(ra, mapping, filp); + ra_submit(ra, mapping, filp); } /** _