From patchwork Tue Apr 14 15:02:10 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Matthew Wilcox (Oracle)" X-Patchwork-Id: 11488311 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9927092C for ; Tue, 14 Apr 2020 15:21:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7C1312064A for ; Tue, 14 Apr 2020 15:21:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="q470B9tg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2438613AbgDNPVJ (ORCPT ); Tue, 14 Apr 2020 11:21:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43520 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405589AbgDNPCj (ORCPT ); Tue, 14 Apr 2020 11:02:39 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C7FC4C061A0E; Tue, 14 Apr 2020 08:02:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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=vyElWKU1zfCiLUTPH8gs8z9Mck1LnRKWxy/aI6BlYH8=; b=q470B9tgV2J9uf4Ht34DKyaYey gND9aWN1jMIz8qi0LIvC5dgb3ywaqARw6r6WTS3RA0ESPGGnu/a0JGPGaI1QyiYlEjl6wK9ldPMvW S+qMR/ErV7s1Dvwcu2OxBpFASLTlhmOEDr4vH6rzM1wn6ZC/soGwkU41sHib018BXBxVdyUcBrAqb gXGx9LG8wHRlVW+F+KihhQPwYljRHquEodSd3jGc5WBmNlOr1uDNZX/OkCwwzQJ1MN174v80xQmZO 15WuH4ExvCLpQyZ7Z+zil0vwnhfE/F4PdbNC8b/ohMMjxrA3XTgIk6/VwdLNUuOFK6zOyy0/u4Npm 5E9PwWUA==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jON59-0006Nz-Ou; Tue, 14 Apr 2020 15:02:35 +0000 From: Matthew Wilcox To: Andrew Morton Cc: "Matthew Wilcox (Oracle)" , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, ocfs2-devel@oss.oracle.com, linux-xfs@vger.kernel.org, Dave Chinner , John Hubbard , Christoph Hellwig , William Kucharski Subject: [PATCH v11 02/25] mm: Return void from various readahead functions Date: Tue, 14 Apr 2020 08:02:10 -0700 Message-Id: <20200414150233.24495-3-willy@infradead.org> X-Mailer: git-send-email 2.21.1 In-Reply-To: <20200414150233.24495-1-willy@infradead.org> References: <20200414150233.24495-1-willy@infradead.org> MIME-Version: 1.0 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org From: "Matthew Wilcox (Oracle)" 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(). Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Dave Chinner Reviewed-by: John Hubbard Reviewed-by: Christoph Hellwig Reviewed-by: William Kucharski --- mm/fadvise.c | 4 ---- mm/internal.h | 12 ++++++------ mm/readahead.c | 31 +++++++++++++------------------ 3 files changed, 19 insertions(+), 28 deletions(-) diff --git a/mm/fadvise.c b/mm/fadvise.c index 3efebfb9952c..0e66f2aaeea3 100644 --- a/mm/fadvise.c +++ b/mm/fadvise.c @@ -104,10 +104,6 @@ int generic_fadvise(struct file *file, loff_t offset, loff_t len, int advice) 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: diff --git a/mm/internal.h b/mm/internal.h index 25fee17c7334..f762a34b0c57 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -49,20 +49,20 @@ void unmap_page_range(struct mmu_gather *tlb, 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); } /** diff --git a/mm/readahead.c b/mm/readahead.c index 2fe72cd29b47..41a592886da7 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -149,10 +149,8 @@ static int read_pages(struct address_space *mapping, struct file *filp, * 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(struct address_space *mapping, 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(struct address_space *mapping, 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 address_space *mapping, struct file *filp, offset += this_chunk; nr_to_read -= this_chunk; } - return 0; } /* @@ -378,11 +373,10 @@ static int try_context_readahead(struct address_space *mapping, /* * 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 *mapping, 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 *mapping, * 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 @@ ondemand_readahead(struct address_space *mapping, } } - return ra_submit(ra, mapping, filp); + ra_submit(ra, mapping, filp); } /**