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Mon, 17 Feb 2020 18:46:29 GMT Received: from userp2040.oracle.com (userp2040.oracle.com [156.151.31.90]) by aserp3030.oracle.com with ESMTP id 2y6t6u5y2u-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Mon, 17 Feb 2020 18:46:29 +0000 Received: from pps.filterd (userp2040.oracle.com [127.0.0.1]) by userp2040.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 01HIiEVK031188 for ; Mon, 17 Feb 2020 18:46:28 GMT Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by userp2040.oracle.com with ESMTP id 2y7tus5gt3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Mon, 17 Feb 2020 18:46:28 +0000 Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j3lPL-00058v-ER; Mon, 17 Feb 2020 18:46:15 +0000 From: Matthew Wilcox To: linux-fsdevel@vger.kernel.org Date: Mon, 17 Feb 2020 10:45:46 -0800 Message-Id: <20200217184613.19668-6-willy@infradead.org> X-Mailer: git-send-email 2.21.1 In-Reply-To: <20200217184613.19668-1-willy@infradead.org> References: <20200217184613.19668-1-willy@infradead.org> MIME-Version: 1.0 X-PDR: PASS X-Source-IP: 198.137.202.133 X-ServerName: bombadil.infradead.org X-Proofpoint-SPF-Result: None X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9534 signatures=668685 X-Proofpoint-Spam-Details: rule=tap_spam_policies_notspam policy=tap_spam_policies score=0 malwarescore=0 mlxlogscore=604 mlxscore=0 suspectscore=1 spamscore=0 priorityscore=0 adultscore=0 phishscore=0 impostorscore=0 clxscore=202 lowpriorityscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002170152 X-Spam: Clean X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=786 mlxscore=0 malwarescore=0 bulkscore=0 spamscore=0 suspectscore=1 phishscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002170152 Cc: linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, linux-mm@kvack.org, ocfs2-devel@oss.oracle.com, linux-ext4@vger.kernel.org, linux-erofs@lists.ozlabs.org, linux-btrfs@vger.kernel.org Subject: [Ocfs2-devel] [PATCH v6 04/16] mm: Tweak readahead loop slightly X-BeenThere: ocfs2-devel@oss.oracle.com X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: ocfs2-devel-bounces@oss.oracle.com Errors-To: ocfs2-devel-bounces@oss.oracle.com X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9534 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 phishscore=0 suspectscore=0 mlxscore=0 malwarescore=0 bulkscore=0 adultscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002170160 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9534 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 impostorscore=0 adultscore=0 spamscore=0 priorityscore=1501 suspectscore=0 clxscore=1034 bulkscore=0 phishscore=0 mlxlogscore=999 lowpriorityscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002170160 From: "Matthew Wilcox (Oracle)" Eliminate the page_offset variable which was just confusing; record the start of each consecutive run of pages in the readahead_control, and move the 'kick off a fresh batch' code to the end of the function for easier use in the next patch. Signed-off-by: Matthew Wilcox (Oracle) --- mm/readahead.c | 31 +++++++++++++++++++------------ 1 file changed, 19 insertions(+), 12 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index 15329309231f..74791b96013f 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -154,7 +154,6 @@ void __do_page_cache_readahead(struct address_space *mapping, unsigned long lookahead_size) { struct inode *inode = mapping->host; - struct page *page; unsigned long end_index; /* The last page we want to read */ LIST_HEAD(page_pool); int page_idx; @@ -163,6 +162,7 @@ void __do_page_cache_readahead(struct address_space *mapping, struct readahead_control rac = { .mapping = mapping, .file = filp, + ._start = offset, ._nr_pages = 0, }; @@ -175,32 +175,39 @@ void __do_page_cache_readahead(struct address_space *mapping, * Preallocate as many pages as we will need. */ for (page_idx = 0; page_idx < nr_to_read; page_idx++) { - pgoff_t page_offset = offset + page_idx; + struct page *page; - if (page_offset > end_index) + if (offset > end_index) break; - page = xa_load(&mapping->i_pages, page_offset); + page = xa_load(&mapping->i_pages, offset); if (page && !xa_is_value(page)) { /* - * Page already present? Kick off the current batch of - * contiguous pages before continuing with the next - * batch. + * Page already present? Kick off the current batch + * of contiguous pages before continuing with the + * next batch. This page may be the one we would + * have intended to mark as Readahead, but we don't + * have a stable reference to this page, and it's + * not worth getting one just for that. */ - if (readahead_count(&rac)) - read_pages(&rac, &page_pool, gfp_mask); - rac._nr_pages = 0; - continue; + goto read; } page = __page_cache_alloc(gfp_mask); if (!page) break; - page->index = page_offset; + page->index = offset; list_add(&page->lru, &page_pool); if (page_idx == nr_to_read - lookahead_size) SetPageReadahead(page); rac._nr_pages++; + offset++; + continue; +read: + if (readahead_count(&rac)) + read_pages(&rac, &page_pool, gfp_mask); + rac._nr_pages = 0; + rac._start = ++offset; } /*