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Wed, 19 Feb 2020 21:01:16 GMT Received: from userp2040.oracle.com (userp2040.oracle.com [156.151.31.90]) by aserp3020.oracle.com with ESMTP id 2y8ud7p5m3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Wed, 19 Feb 2020 21:01:16 +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 01JKwYFc025004 for ; Wed, 19 Feb 2020 21:01:15 GMT Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by userp2040.oracle.com with ESMTP id 2y98qxbxsf-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Wed, 19 Feb 2020 21:01:13 +0000 Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j4WSv-0008Tm-1k; Wed, 19 Feb 2020 21:01:05 +0000 From: Matthew Wilcox To: linux-fsdevel@vger.kernel.org Date: Wed, 19 Feb 2020 13:00:48 -0800 Message-Id: <20200219210103.32400-10-willy@infradead.org> X-Mailer: git-send-email 2.21.1 In-Reply-To: <20200219210103.32400-1-willy@infradead.org> References: <20200219210103.32400-1-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=9536 signatures=668685 X-Proofpoint-Spam-Details: rule=tap_spam_policies_notspam policy=tap_spam_policies score=0 impostorscore=0 priorityscore=30 mlxscore=0 lowpriorityscore=0 phishscore=0 clxscore=221 bulkscore=0 mlxlogscore=815 malwarescore=0 adultscore=0 spamscore=0 suspectscore=1 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002190156 X-Spam: Clean X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 mlxlogscore=999 phishscore=0 suspectscore=1 mlxscore=0 malwarescore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002190156 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 v7 09/24] mm: Put readahead pages in cache earlier 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=9536 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 phishscore=0 mlxlogscore=999 mlxscore=0 adultscore=0 spamscore=0 suspectscore=0 malwarescore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002190156 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9536 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 lowpriorityscore=0 suspectscore=0 spamscore=0 priorityscore=1501 adultscore=0 mlxscore=0 clxscore=1034 malwarescore=0 mlxlogscore=999 phishscore=0 impostorscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002190156 From: "Matthew Wilcox (Oracle)" When populating the page cache for readahead, mappings that use ->readpages must populate the page cache themselves as the pages are passed on a linked list which would normally be used for the page cache's LRU. For mappings that use ->readpage or the upcoming ->readahead method, we can put the pages into the page cache as soon as they're allocated, which solves a race between readahead and direct IO. It also lets us remove the gfp argument from read_pages(). Use the new readahead_page() API to implement the repeated calls to ->readpage(), just like most filesystems will. This iterator also supports huge pages, even though none of the filesystems have been converted to use them yet. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Christoph Hellwig --- include/linux/pagemap.h | 20 +++++++++++++++++ mm/readahead.c | 48 +++++++++++++++++++++++++---------------- 2 files changed, 49 insertions(+), 19 deletions(-) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 55fcea0249e6..4989d330fada 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -647,8 +647,28 @@ struct readahead_control { /* private: use the readahead_* accessors instead */ pgoff_t _index; unsigned int _nr_pages; + unsigned int _batch_count; }; +static inline struct page *readahead_page(struct readahead_control *rac) +{ + struct page *page; + + BUG_ON(rac->_batch_count > rac->_nr_pages); + rac->_nr_pages -= rac->_batch_count; + rac->_index += rac->_batch_count; + rac->_batch_count = 0; + + if (!rac->_nr_pages) + return NULL; + + page = xa_load(&rac->mapping->i_pages, rac->_index); + VM_BUG_ON_PAGE(!PageLocked(page), page); + rac->_batch_count = hpage_nr_pages(page); + + return page; +} + /* The number of pages in this readahead block */ static inline unsigned int readahead_count(struct readahead_control *rac) { diff --git a/mm/readahead.c b/mm/readahead.c index 83df5c061d33..aaa209559ba2 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -113,15 +113,14 @@ int read_cache_pages(struct address_space *mapping, struct list_head *pages, EXPORT_SYMBOL(read_cache_pages); -static void read_pages(struct readahead_control *rac, struct list_head *pages, - gfp_t gfp) +static void read_pages(struct readahead_control *rac, struct list_head *pages) { const struct address_space_operations *aops = rac->mapping->a_ops; + struct page *page; struct blk_plug plug; - unsigned page_idx; if (!readahead_count(rac)) - return; + goto out; blk_start_plug(&plug); @@ -130,23 +129,23 @@ static void read_pages(struct readahead_control *rac, struct list_head *pages, readahead_count(rac)); /* Clean up the remaining pages */ put_pages_list(pages); - goto out; - } - - for (page_idx = 0; page_idx < readahead_count(rac); page_idx++) { - struct page *page = lru_to_page(pages); - list_del(&page->lru); - if (!add_to_page_cache_lru(page, rac->mapping, page->index, - gfp)) + rac->_index += rac->_nr_pages; + rac->_nr_pages = 0; + } else { + while ((page = readahead_page(rac))) { aops->readpage(rac->file, page); - put_page(page); + put_page(page); + } } -out: blk_finish_plug(&plug); BUG_ON(!list_empty(pages)); - rac->_nr_pages = 0; + BUG_ON(readahead_count(rac)); + +out: + /* If we were called due to a conflicting page, skip over it */ + rac->_index++; } /* @@ -165,9 +164,11 @@ void __do_page_cache_readahead(struct address_space *mapping, LIST_HEAD(page_pool); loff_t isize = i_size_read(inode); gfp_t gfp_mask = readahead_gfp_mask(mapping); + bool use_list = mapping->a_ops->readpages; struct readahead_control rac = { .mapping = mapping, .file = filp, + ._index = index, ._nr_pages = 0, }; unsigned long i; @@ -184,6 +185,8 @@ void __do_page_cache_readahead(struct address_space *mapping, if (index + i > end_index) break; + BUG_ON(index + i != rac._index + rac._nr_pages); + page = xa_load(&mapping->i_pages, index + i); if (page && !xa_is_value(page)) { /* @@ -191,15 +194,22 @@ void __do_page_cache_readahead(struct address_space *mapping, * contiguous pages before continuing with the next * batch. */ - read_pages(&rac, &page_pool, gfp_mask); + read_pages(&rac, &page_pool); continue; } page = __page_cache_alloc(gfp_mask); if (!page) break; - page->index = index + i; - list_add(&page->lru, &page_pool); + if (use_list) { + page->index = index + i; + list_add(&page->lru, &page_pool); + } else if (add_to_page_cache_lru(page, mapping, index + i, + gfp_mask) < 0) { + put_page(page); + read_pages(&rac, &page_pool); + continue; + } if (i == nr_to_read - lookahead_size) SetPageReadahead(page); rac._nr_pages++; @@ -210,7 +220,7 @@ void __do_page_cache_readahead(struct address_space *mapping, * uptodate then the caller will launch readpage again, and * will then handle the error. */ - read_pages(&rac, &page_pool, gfp_mask); + read_pages(&rac, &page_pool); } /*