From patchwork Thu Jul 27 15:20:19 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chengming Zhou X-Patchwork-Id: 13330277 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 089A9C0015E for ; Thu, 27 Jul 2023 15:21:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234567AbjG0PVr (ORCPT ); Thu, 27 Jul 2023 11:21:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35494 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234559AbjG0PVp (ORCPT ); Thu, 27 Jul 2023 11:21:45 -0400 Received: from out-80.mta0.migadu.com (out-80.mta0.migadu.com [IPv6:2001:41d0:1004:224b::50]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F14D130F0 for ; Thu, 27 Jul 2023 08:21:40 -0700 (PDT) X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1690471299; 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=/sKpoCtxUkYnH2WqkRrOBZ45YFGekx6TcrM1LcTi34Y=; b=GoAulQGyGJtzXSa5IKoRcjIs0s8QPP3zFwnYNiNs+kPVJnExsYqEOYEtlR8fhSpj47xKUw YJMSo28qz6Ff2+WhW4F2MDPA7X0bZeGdSFiNNk7xJAPXm25ysAo4/ta6xcQFVsJP/ROKoX B4SM3TA0HMPPk371Wjn8U3jkybITGKc= From: chengming.zhou@linux.dev To: axboe@kernel.dk, osandov@fb.com, ming.lei@redhat.com, kbusch@kernel.org, krisman@suse.de Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, zhouchengming@bytedance.com Subject: [PATCH v2 2/3] sbitmap: fix strict round-robin non-wrap with hint > 0 Date: Thu, 27 Jul 2023 23:20:19 +0800 Message-ID: <20230727152020.3633009-2-chengming.zhou@linux.dev> In-Reply-To: <20230727152020.3633009-1-chengming.zhou@linux.dev> References: <20230727152020.3633009-1-chengming.zhou@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: Chengming Zhou If we have alloc_hint > 0 and don't wrap, we need to recheck sb->map[index] with hint == 0 to exhaust the map. For example: we have 8 words to search, index == 4, hint > 0 In sb->map[4] word, we only search [hint, 63] bits in the first word search. Then we search left 7 words, the sb->map[4] [0, hint-1] bits aren't searched. This patch fix it by searching 9 words in this case, so we will search sb->map[4] the second time at last with hint == 0. Signed-off-by: Chengming Zhou --- lib/sbitmap.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/lib/sbitmap.c b/lib/sbitmap.c index ac4027884765..6e098a46be26 100644 --- a/lib/sbitmap.c +++ b/lib/sbitmap.c @@ -199,10 +199,18 @@ static int sbitmap_find_bit(struct sbitmap *sb, unsigned int alloc_hint, bool wrap) { + unsigned int map_nr = sb->map_nr; unsigned int i; int nr = -1; - for (i = 0; i < sb->map_nr; i++) { + /* + * If we have alloc_hint > 0 and don't wrap, we need to + * recheck sb->map[index] with hint == 0 to exhaust the map. + */ + if (alloc_hint && !wrap) + map_nr += 1; + + for (i = 0; i < map_nr; i++) { nr = sbitmap_find_bit_in_word(&sb->map[index], min_t(unsigned int, __map_depth(sb, index),