From patchwork Thu Mar 2 23:16:37 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Howells X-Patchwork-Id: 13158038 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 58B5CC678D4 for ; Thu, 2 Mar 2023 23:18:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229825AbjCBXSV (ORCPT ); Thu, 2 Mar 2023 18:18:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60404 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229810AbjCBXSP (ORCPT ); Thu, 2 Mar 2023 18:18:15 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 13468580FF for ; Thu, 2 Mar 2023 15:17:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1677799015; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=nNYSQ/Y9B3aZRJt+LYUgV6EcG7vLla4aEHu0riyXHik=; b=T+EU/v3L66r3qxhADmmDUXrcr/7+6v3GBscNSRndEYbWpF2KSgkAsZ2+15KbI7Dujc2Rek psHTF3FhgX5KqDiaAJYaK+3E/ZuLP8DJPJOVBbQXIPf82qryOD8WFZLg64jDQw7XwoRVXW s6A6SnVXRLZ03wYrGa4CwVFtpCaHJh4= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-640-Ema7s1klNeSsDP6d3fPMHw-1; Thu, 02 Mar 2023 18:16:50 -0500 X-MC-Unique: Ema7s1klNeSsDP6d3fPMHw-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 2767F1C05AC1; Thu, 2 Mar 2023 23:16:49 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.18]) by smtp.corp.redhat.com (Postfix) with ESMTP id 15443492C3E; Thu, 2 Mar 2023 23:16:46 +0000 (UTC) From: David Howells To: Linus Torvalds , Steve French Cc: David Howells , Vishal Moola , Shyam Prasad N , Rohith Surabattula , Tom Talpey , Stefan Metzmacher , Paulo Alcantara , Jeff Layton , Matthew Wilcox , Marc Dionne , linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Steve French , Andrew Morton , linux-mm@kvack.org Subject: [PATCH 2/3] afs: Partially revert and use filemap_get_folio_tag() Date: Thu, 2 Mar 2023 23:16:37 +0000 Message-Id: <20230302231638.521280-3-dhowells@redhat.com> In-Reply-To: <20230302231638.521280-1-dhowells@redhat.com> References: <20230302231638.521280-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org Partially revert the changes made by: acc8d8588cb7e3e64b0d2fa611dad06574cd67b1. afs: convert afs_writepages_region() to use filemap_get_folios_tag() The issue is that filemap_get_folios_tag() gets a batch of pages at a time, and then afs_writepages_region() goes through them one at a time, extends each into an operation with as many pages as will fit using the loop in afs_extend_writeback() and submits it - but, in the common case, this means that the other pages in the batch already got annexed and processed in afs_extend_writeback() and we end up doing duplicate processing. Switching to write_cache_pages() isn't an immediate substitute as that doesn't take account of PG_fscache (and this bit is used in other ways by other filesystems). So go back to finding the next folio from the VM one at a time and then extending the op onwards. Fixes: acc8d8588cb7 ("afs: convert afs_writepages_region() to use filemap_get_folios_tag()") Signed-off-by: David Howells cc: Linus Torvalds cc: Marc Dionne cc: Steve French cc: "Vishal Moola (Oracle)" cc: "Matthew Wilcox (Oracle)" cc: Andrew Morton cc: linux-afs@lists.infradead.org cc: linux-mm@kvack.org Link: https://lore.kernel.org/r/2214157.1677250083@warthog.procyon.org.uk/ --- fs/afs/write.c | 118 ++++++++++++++++++++++++------------------------- 1 file changed, 57 insertions(+), 61 deletions(-) diff --git a/fs/afs/write.c b/fs/afs/write.c index 571f3b9a417e..2ed76697be96 100644 --- a/fs/afs/write.c +++ b/fs/afs/write.c @@ -704,87 +704,83 @@ static int afs_writepages_region(struct address_space *mapping, bool max_one_loop) { struct folio *folio; - struct folio_batch fbatch; ssize_t ret; - unsigned int i; - int n, skips = 0; + int skips = 0; _enter("%llx,%llx,", start, end); - folio_batch_init(&fbatch); do { pgoff_t index = start / PAGE_SIZE; - n = filemap_get_folios_tag(mapping, &index, end / PAGE_SIZE, - PAGECACHE_TAG_DIRTY, &fbatch); - - if (!n) + folio = filemap_get_folio_tag(mapping, &index, end / PAGE_SIZE, + PAGECACHE_TAG_DIRTY); + if (!folio) break; - for (i = 0; i < n; i++) { - folio = fbatch.folios[i]; - start = folio_pos(folio); /* May regress with THPs */ - _debug("wback %lx", folio_index(folio)); + start = folio_pos(folio); /* May regress with THPs */ - /* At this point we hold neither the i_pages lock nor the - * page lock: the page may be truncated or invalidated - * (changing page->mapping to NULL), or even swizzled - * back from swapper_space to tmpfs file mapping - */ - if (wbc->sync_mode != WB_SYNC_NONE) { - ret = folio_lock_killable(folio); - if (ret < 0) { - folio_batch_release(&fbatch); - return ret; - } - } else { - if (!folio_trylock(folio)) - continue; - } + _debug("wback %lx", folio_index(folio)); - if (folio->mapping != mapping || - !folio_test_dirty(folio)) { - start += folio_size(folio); - folio_unlock(folio); - continue; + /* At this point we hold neither the i_pages lock nor the + * page lock: the page may be truncated or invalidated + * (changing page->mapping to NULL), or even swizzled + * back from swapper_space to tmpfs file mapping + */ + if (wbc->sync_mode != WB_SYNC_NONE) { + ret = folio_lock_killable(folio); + if (ret < 0) { + folio_put(folio); + return ret; + } + } else { + if (!folio_trylock(folio)) { + folio_put(folio); + return 0; } + } - if (folio_test_writeback(folio) || - folio_test_fscache(folio)) { - folio_unlock(folio); - if (wbc->sync_mode != WB_SYNC_NONE) { - folio_wait_writeback(folio); + if (folio_mapping(folio) != mapping || + !folio_test_dirty(folio)) { + start += folio_size(folio); + folio_unlock(folio); + folio_put(folio); + continue; + } + + if (folio_test_writeback(folio) || + folio_test_fscache(folio)) { + folio_unlock(folio); + if (wbc->sync_mode != WB_SYNC_NONE) { + folio_wait_writeback(folio); #ifdef CONFIG_AFS_FSCACHE - folio_wait_fscache(folio); + folio_wait_fscache(folio); #endif - } else { - start += folio_size(folio); - } - if (wbc->sync_mode == WB_SYNC_NONE) { - if (skips >= 5 || need_resched()) { - *_next = start; - _leave(" = 0 [%llx]", *_next); - return 0; - } - skips++; - } - continue; + } else { + start += folio_size(folio); } - - if (!folio_clear_dirty_for_io(folio)) - BUG(); - ret = afs_write_back_from_locked_folio(mapping, wbc, - folio, start, end); - if (ret < 0) { - _leave(" = %zd", ret); - folio_batch_release(&fbatch); - return ret; + folio_put(folio); + if (wbc->sync_mode == WB_SYNC_NONE) { + if (skips >= 5 || need_resched()) + break; + skips++; } + continue; + } - start += ret; + if (!folio_clear_dirty_for_io(folio)) + BUG(); + ret = afs_write_back_from_locked_folio(mapping, wbc, folio, start, end); + folio_put(folio); + if (ret < 0) { + _leave(" = %zd", ret); + return ret; } - folio_batch_release(&fbatch); + start += ret; + + if (max_one_loop) + break; + cond_resched(); } while (wbc->nr_to_write > 0);