From patchwork Fri Sep 24 17:18:41 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 12516245 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 41FB2C433FE for ; Fri, 24 Sep 2021 17:20:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2C7BA60F21 for ; Fri, 24 Sep 2021 17:20:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344400AbhIXRVm (ORCPT ); Fri, 24 Sep 2021 13:21:42 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:43863 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347808AbhIXRU1 (ORCPT ); Fri, 24 Sep 2021 13:20:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632503933; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Wh92/GIQSWuimSHEUrh/KLNHrbQS0s/D/rLAazMZI+U=; b=f8uJXzBxwn5QtAtLpTvkorUshsPcz2+00rm0FhyFRPW+TTC5DSGa9hoqc5nvykJO2rt9xL 4bGnNfHZB8KnHaT9t1QnkldOptN3gahbkHnAikdrSh54HY49vujhz0+/xeNvIhGRrDElnh HBj9xWvhVyKRdQzkvjd3KCq3seoUYhY= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-400-gHqa0HBcMl20u-8s2KXwMA-1; Fri, 24 Sep 2021 13:18:51 -0400 X-MC-Unique: gHqa0HBcMl20u-8s2KXwMA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 2220E1922023; Fri, 24 Sep 2021 17:18:49 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.44]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2CBB21017E36; Fri, 24 Sep 2021 17:18:42 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH v3 5/9] mm: Make swap_readpage() for SWP_FS_OPS use ->swap_rw() not ->readpage() From: David Howells To: willy@infradead.org, hch@lst.de, trond.myklebust@primarydata.com Cc: Jens Axboe , "Darrick J. Wong" , linux-block@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, dhowells@redhat.com, dhowells@redhat.com, darrick.wong@oracle.com, viro@zeniv.linux.org.uk, jlayton@kernel.org, torvalds@linux-foundation.org, linux-nfs@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Fri, 24 Sep 2021 18:18:41 +0100 Message-ID: <163250392134.2330363.2715808422502485629.stgit@warthog.procyon.org.uk> In-Reply-To: <163250387273.2330363.13240781819520072222.stgit@warthog.procyon.org.uk> References: <163250387273.2330363.13240781819520072222.stgit@warthog.procyon.org.uk> User-Agent: StGit/0.23 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org Make swap_readpage() use the ->swap_rw() method on the filesystem to do direct I/O rather then ->readpage() when accessing a swap file (SWP_FS_OPS). Make swap_writepage() similarly use ->swap_rw() also rather than the ->direct_IO() method. Suggested-by: Matthew Wilcox (Oracle) Signed-off-by: David Howells cc: Matthew Wilcox cc: Christoph Hellwig cc: Jens Axboe cc: Darrick J. Wong cc: linux-block@vger.kernel.org cc: linux-xfs@vger.kernel.org cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org --- include/linux/fs.h | 2 + mm/page_io.c | 106 +++++++++++++++++++++++++++++++++++++++++++++++----- 2 files changed, 98 insertions(+), 10 deletions(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index c20f4423e2f1..c8f7724ecded 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -338,6 +338,7 @@ struct kiocb { union { unsigned int ki_cookie; /* for ->iopoll */ struct wait_page_queue *ki_waitq; /* for async buffered IO */ + struct page *ki_swap_page; /* For swapfile_read/write */ }; randomized_struct_fields_end @@ -404,6 +405,7 @@ struct address_space_operations { int (*releasepage) (struct page *, gfp_t); void (*freepage)(struct page *); ssize_t (*direct_IO)(struct kiocb *, struct iov_iter *iter); + ssize_t (*swap_rw)(struct kiocb *, struct iov_iter *); /* * migrate the contents of a page to the specified target. If * migrate_mode is MIGRATE_ASYNC, it must not block. diff --git a/mm/page_io.c b/mm/page_io.c index b9fe25101a39..6b1465699c72 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -4,7 +4,7 @@ * * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds * - * Swap reorganised 29.12.95, + * Swap reorganised 29.12.95, * Asynchronous swapping added 30.12.95. Stephen Tweedie * Removed race in async swapping. 14.4.1996. Bruno Haible * Add swap of shared pages through the page cache. 20.2.1998. Stephen Tweedie @@ -26,6 +26,22 @@ #include #include +/* + * Keep track of the kiocb we're using to do async DIO. We have to + * refcount it until various things stop looking at the kiocb *after* + * calling ->ki_complete(). + */ +struct swapfile_kiocb { + struct kiocb iocb; + refcount_t ref; +}; + +static void swapfile_put_kiocb(struct swapfile_kiocb *ki) +{ + if (refcount_dec_and_test(&ki->ref)) + kfree(ki); +} + static void end_swap_bio_write(struct bio *bio) { struct page *page = bio_first_page_all(bio); @@ -302,11 +318,12 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc) iov_iter_bvec(&from, WRITE, &bv, 1, PAGE_SIZE); init_sync_kiocb(&kiocb, swap_file); - kiocb.ki_pos = page_file_offset(page); + kiocb.ki_pos = page_file_offset(page); + kiocb.ki_flags = IOCB_DIRECT | IOCB_WRITE | IOCB_SWAP; set_page_writeback(page); unlock_page(page); - ret = mapping->a_ops->direct_IO(&kiocb, &from); + ret = mapping->a_ops->swap_rw(&kiocb, &from); if (ret == PAGE_SIZE) { count_vm_event(PSWPOUT); ret = 0; @@ -323,8 +340,8 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc) */ set_page_dirty(page); ClearPageReclaim(page); - pr_err_ratelimited("Write error on dio swapfile (%llu)\n", - page_file_offset(page)); + pr_err_ratelimited("Write error (%d) on dio swapfile (%llu)\n", + ret, page_file_offset(page)); } end_page_writeback(page); return ret; @@ -352,6 +369,79 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc) return 0; } +static void swapfile_read_complete(struct page *page, long ret) +{ + if (ret == page_size(page)) { + count_vm_event(PSWPIN); + SetPageUptodate(page); + } else { + SetPageError(page); + pr_err_ratelimited("Read error (%ld) on dio swapfile (%llu)\n", + ret, page_file_offset(page)); + } + + unlock_page(page); +} + +static void __swapfile_read_complete(struct kiocb *iocb, long ret, long ret2) +{ + struct swapfile_kiocb *ki = container_of(iocb, struct swapfile_kiocb, iocb); + + swapfile_read_complete(iocb->ki_swap_page, ret); + swapfile_put_kiocb(ki); +} + +static void swapfile_read_sync(struct swap_info_struct *sis, struct page *page, + struct iov_iter *to) +{ + struct kiocb kiocb; + struct file *swap_file = sis->swap_file; + int ret; + + init_sync_kiocb(&kiocb, swap_file); + kiocb.ki_swap_page = page; + kiocb.ki_pos = page_file_offset(page); + kiocb.ki_flags = IOCB_DIRECT | IOCB_SWAP; + ret = swap_file->f_mapping->a_ops->swap_rw(&kiocb, to); + + swapfile_read_complete(page, ret); +} + +static void swapfile_read(struct swap_info_struct *sis, struct page *page, + bool synchronous) +{ + struct swapfile_kiocb *ki; + struct file *swap_file = sis->swap_file; + struct bio_vec bv = { + .bv_page = page, + .bv_len = thp_size(page), + .bv_offset = 0 + }; + struct iov_iter to; + int ret; + + iov_iter_bvec(&to, READ, &bv, 1, thp_size(page)); + + if (synchronous) + return swapfile_read_sync(sis, page, &to); + + ki = kzalloc(sizeof(*ki), GFP_KERNEL); + if (!ki) + return; + + refcount_set(&ki->ref, 2); + init_sync_kiocb(&ki->iocb, swap_file); + ki->iocb.ki_swap_page = page; + ki->iocb.ki_flags = IOCB_DIRECT | IOCB_SWAP; + ki->iocb.ki_pos = page_file_offset(page); + ki->iocb.ki_complete = __swapfile_read_complete; + + ret = swap_file->f_mapping->a_ops->swap_rw(&ki->iocb, &to); + if (ret != -EIOCBQUEUED) + __swapfile_read_complete(&ki->iocb, ret, 0); + swapfile_put_kiocb(ki); +} + void swap_readpage(struct page *page, bool synchronous) { struct bio *bio; @@ -378,11 +468,7 @@ void swap_readpage(struct page *page, bool synchronous) } if (data_race(sis->flags & SWP_FS_OPS)) { - struct file *swap_file = sis->swap_file; - struct address_space *mapping = swap_file->f_mapping; - - if (!mapping->a_ops->readpage(swap_file, page)) - count_vm_event(PSWPIN); + swapfile_read(sis, page, synchronous); goto out; }