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Fri, 21 Feb 2020 04:24:54 +0000 (UTC) Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Thu, 20 Feb 2020 20:24:39 -0800 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Thu, 20 Feb 2020 20:24:53 -0800 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Thu, 20 Feb 2020 20:24:53 -0800 Received: from [10.110.48.28] (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Fri, 21 Feb 2020 04:24:52 +0000 Subject: Re: [PATCH v7 04/24] mm: Move readahead nr_pages check into read_pages To: Matthew Wilcox , CC: , , , , , , , , References: <20200219210103.32400-1-willy@infradead.org> <20200219210103.32400-5-willy@infradead.org> X-Nvconfidentiality: public From: John Hubbard Message-ID: <89a2e3d1-df95-f006-24d9-76a4b7dd230b@nvidia.com> Date: Thu, 20 Feb 2020 20:24:52 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200219210103.32400-5-willy@infradead.org> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL105.nvidia.com (172.20.187.12) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1582259079; bh=ASKxt3bijyoYwdw1pDufntJpHzO9oNcu8Dw674S+ZbU=; h=X-PGP-Universal:Subject:To:CC:References:X-Nvconfidentiality:From: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=heUrjhw3xqeEYQuBuoBasbu56gpWlnwZt+AdI2wq+B9NZbvczA0FSHtDGsaVb4Naf bnLZHSctgsoXIEuM1CeqQs2bSg86B5wpOR88JYaRMGaVNCFZ0llOWVBqfWBe1dfYIU BUwh2YAMS+RWhS/AXveX566mq203Kwd9VMWWIOhSUurQzAI72ujnD9tt6+SnD57HYI MgI6ngKNa6Eh0y5HdQDTDz6lnM06+eXX5yP8YrN+QsAaNtRrwPlFUiL3IiVJfgaM4Y DJpi7QNVd6PQYwtQElVUeLezKB5OQAGRgilG6WKFgkE2WbMHVP2VGJNm3q3F0+FJmu 6lrj9yx0IYl2Q== 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: On 2/19/20 1:00 PM, Matthew Wilcox wrote: > From: "Matthew Wilcox (Oracle)" > > Simplify the callers by moving the check for nr_pages and the BUG_ON > into read_pages(). > > Signed-off-by: Matthew Wilcox (Oracle) > --- > mm/readahead.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > Looks nice, Reviewed-by: John Hubbard thanks, -- John Hubbard NVIDIA > diff --git a/mm/readahead.c b/mm/readahead.c > index 61b15b6b9e72..9fcd4e32b62d 100644 > --- a/mm/readahead.c > +++ b/mm/readahead.c > @@ -119,6 +119,9 @@ static void read_pages(struct address_space *mapping, struct file *filp, > struct blk_plug plug; > unsigned page_idx; > > + if (!nr_pages) > + return; > + > blk_start_plug(&plug); > > if (mapping->a_ops->readpages) { > @@ -138,6 +141,8 @@ static void read_pages(struct address_space *mapping, struct file *filp, > > out: > blk_finish_plug(&plug); > + > + BUG_ON(!list_empty(pages)); > } > > /* > @@ -180,8 +185,7 @@ void __do_page_cache_readahead(struct address_space *mapping, > * contiguous pages before continuing with the next > * batch. > */ > - if (nr_pages) > - read_pages(mapping, filp, &page_pool, nr_pages, > + read_pages(mapping, filp, &page_pool, nr_pages, > gfp_mask); > nr_pages = 0; > continue; > @@ -202,9 +206,7 @@ void __do_page_cache_readahead(struct address_space *mapping, > * uptodate then the caller will launch readpage again, and > * will then handle the error. > */ > - if (nr_pages) > - read_pages(mapping, filp, &page_pool, nr_pages, gfp_mask); > - BUG_ON(!list_empty(&page_pool)); > + read_pages(mapping, filp, &page_pool, nr_pages, gfp_mask); > } > > /* >