From patchwork Wed Feb 19 21:00:49 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 11392587 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 1B023138D for ; Wed, 19 Feb 2020 21:02:14 +0000 (UTC) Received: from aserp2120.oracle.com (aserp2120.oracle.com [141.146.126.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E33792467E for ; Wed, 19 Feb 2020 21:02:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E33792467E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=ocfs2-devel-bounces@oss.oracle.com Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 01JL1mw0160055; 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Wed, 19 Feb 2020 21:01:19 GMT Received: from userp2030.oracle.com (userp2030.oracle.com [156.151.31.89]) by userp3030.oracle.com with ESMTP id 2y8ud47psy-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Wed, 19 Feb 2020 21:01:18 +0000 Received: from pps.filterd (userp2030.oracle.com [127.0.0.1]) by userp2030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 01JKxtrH017886 for ; Wed, 19 Feb 2020 21:01:17 GMT Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by userp2030.oracle.com with ESMTP id 2y9axp1g10-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Wed, 19 Feb 2020 21:01:17 +0000 Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j4WSv-0008Tq-2n; Wed, 19 Feb 2020 21:01:05 +0000 From: Matthew Wilcox To: linux-fsdevel@vger.kernel.org Date: Wed, 19 Feb 2020 13:00:49 -0800 Message-Id: <20200219210103.32400-11-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 malwarescore=0 spamscore=0 phishscore=0 lowpriorityscore=0 clxscore=169 adultscore=0 bulkscore=0 suspectscore=1 mlxlogscore=999 impostorscore=0 mlxscore=0 priorityscore=30 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 phishscore=0 mlxlogscore=999 mlxscore=0 adultscore=0 spamscore=0 suspectscore=1 malwarescore=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 10/24] mm: Add readahead address space operation 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)" This replaces ->readpages with a saner interface: - Return void instead of an ignored error code. - Page cache is already populated with locked pages when ->readahead is called. - New arguments can be passed to the implementation without changing all the filesystems that use a common helper function like mpage_readahead(). Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Christoph Hellwig --- Documentation/filesystems/locking.rst | 6 +++++- Documentation/filesystems/vfs.rst | 15 +++++++++++++++ include/linux/fs.h | 2 ++ include/linux/pagemap.h | 18 ++++++++++++++++++ mm/readahead.c | 12 ++++++++++-- 5 files changed, 50 insertions(+), 3 deletions(-) diff --git a/Documentation/filesystems/locking.rst b/Documentation/filesystems/locking.rst index 5057e4d9dcd1..0af2e0e11461 100644 --- a/Documentation/filesystems/locking.rst +++ b/Documentation/filesystems/locking.rst @@ -239,6 +239,7 @@ prototypes:: int (*readpage)(struct file *, struct page *); int (*writepages)(struct address_space *, struct writeback_control *); int (*set_page_dirty)(struct page *page); + void (*readahead)(struct readahead_control *); int (*readpages)(struct file *filp, struct address_space *mapping, struct list_head *pages, unsigned nr_pages); int (*write_begin)(struct file *, struct address_space *mapping, @@ -271,7 +272,8 @@ writepage: yes, unlocks (see below) readpage: yes, unlocks writepages: set_page_dirty no -readpages: +readahead: yes, unlocks +readpages: no write_begin: locks the page exclusive write_end: yes, unlocks exclusive bmap: @@ -295,6 +297,8 @@ the request handler (/dev/loop). ->readpage() unlocks the page, either synchronously or via I/O completion. +->readahead() unlocks the pages that I/O is attempted on like ->readpage(). + ->readpages() populates the pagecache with the passed pages and starts I/O against them. They come unlocked upon I/O completion. diff --git a/Documentation/filesystems/vfs.rst b/Documentation/filesystems/vfs.rst index 7d4d09dd5e6d..ed17771c212b 100644 --- a/Documentation/filesystems/vfs.rst +++ b/Documentation/filesystems/vfs.rst @@ -706,6 +706,7 @@ cache in your filesystem. The following members are defined: int (*readpage)(struct file *, struct page *); int (*writepages)(struct address_space *, struct writeback_control *); int (*set_page_dirty)(struct page *page); + void (*readahead)(struct readahead_control *); int (*readpages)(struct file *filp, struct address_space *mapping, struct list_head *pages, unsigned nr_pages); int (*write_begin)(struct file *, struct address_space *mapping, @@ -781,12 +782,26 @@ cache in your filesystem. The following members are defined: If defined, it should set the PageDirty flag, and the PAGECACHE_TAG_DIRTY tag in the radix tree. +``readahead`` + Called by the VM to read pages associated with the address_space + object. The pages are consecutive in the page cache and are + locked. The implementation should decrement the page refcount + after starting I/O on each page. Usually the page will be + unlocked by the I/O completion handler. If the filesystem decides + to stop attempting I/O before reaching the end of the readahead + window, it can simply return. The caller will decrement the page + refcount and unlock the remaining pages for you. Set PageUptodate + if the I/O completes successfully. Setting PageError on any page + will be ignored; simply unlock the page if an I/O error occurs. + ``readpages`` called by the VM to read pages associated with the address_space object. This is essentially just a vector version of readpage. Instead of just one page, several pages are requested. readpages is only used for read-ahead, so read errors are ignored. If anything goes wrong, feel free to give up. + This interface is deprecated and will be removed by the end of + 2020; implement readahead instead. ``write_begin`` Called by the generic buffered write code to ask the filesystem diff --git a/include/linux/fs.h b/include/linux/fs.h index 3cd4fe6b845e..d4e2d2964346 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -292,6 +292,7 @@ enum positive_aop_returns { struct page; struct address_space; struct writeback_control; +struct readahead_control; /* * Write life time hint values. @@ -375,6 +376,7 @@ struct address_space_operations { */ int (*readpages)(struct file *filp, struct address_space *mapping, struct list_head *pages, unsigned nr_pages); + void (*readahead)(struct readahead_control *); int (*write_begin)(struct file *, struct address_space *mapping, loff_t pos, unsigned len, unsigned flags, diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 4989d330fada..b3008605fd1b 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -669,6 +669,24 @@ static inline struct page *readahead_page(struct readahead_control *rac) return page; } +/* The byte offset into the file of this readahead block */ +static inline loff_t readahead_pos(struct readahead_control *rac) +{ + return (loff_t)rac->_index * PAGE_SIZE; +} + +/* The number of bytes in this readahead block */ +static inline loff_t readahead_length(struct readahead_control *rac) +{ + return (loff_t)rac->_nr_pages * PAGE_SIZE; +} + +/* The index of the first page in this readahead block */ +static inline unsigned int readahead_index(struct readahead_control *rac) +{ + return rac->_index; +} + /* 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 aaa209559ba2..07cdfbf00f4b 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -124,7 +124,14 @@ static void read_pages(struct readahead_control *rac, struct list_head *pages) blk_start_plug(&plug); - if (aops->readpages) { + if (aops->readahead) { + aops->readahead(rac); + /* Clean up the remaining pages */ + while ((page = readahead_page(rac))) { + unlock_page(page); + put_page(page); + } + } else if (aops->readpages) { aops->readpages(rac->file, rac->mapping, pages, readahead_count(rac)); /* Clean up the remaining pages */ @@ -234,7 +241,8 @@ void force_page_cache_readahead(struct address_space *mapping, struct file_ra_state *ra = &filp->f_ra; unsigned long max_pages; - if (unlikely(!mapping->a_ops->readpage && !mapping->a_ops->readpages)) + if (unlikely(!mapping->a_ops->readpage && !mapping->a_ops->readpages && + !mapping->a_ops->readahead)) return; /*