From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id ED0571D86F2; Mon, 26 May 2025 07:57:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748246265; cv=none; b=ZvWc0u4dBe6qSLiNCK0I6qab2W/j9i/J87a2OQSEzFsrcaxd3QeXR/MDMB07DqK7TqD0TSqj+eaxUB4uRugo+Lo6Mb24PcCcxX57dcoIINaLhPFOYi6OKAL9VmQ5075jFOFb6lDF+9M89WtM4157pWXfMBfGgVWwEVmggxXrdmU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748246265; c=relaxed/simple; bh=8jpIJ/PJOv+VNNNCz7eR5MMkKhKD87N05X6jSuQtMjY=; h=Subject:To:Cc:References:From:Message-ID:Date:MIME-Version: In-Reply-To:Content-Type; b=L3bAK8VK2wpkyjkl8k6aSDKrBEZz8/J4y28kVmOxbvkzR+QUpv+sLgXEcqGaM+kMoa3F+tjMUJak1VcsI4RADTRHhxfNc66lCWhtlJ3ki3mz3JxcqNTVYmvmz0ZNV8yzVP83/Rdd55i1HZvtHXbt8ge1JaZoQ5XDyL+ATjF9lI4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.235]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4b5SmN576HzKHMm3; Mon, 26 May 2025 15:57:40 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 2B1461A109A; Mon, 26 May 2025 15:57:39 +0800 (CST) Received: from [10.174.179.143] (unknown [10.174.179.143]) by APP4 (Coremail) with SMTP id gCh0CgAni1_xHjRoDfE2Ng--.33568S3; Mon, 26 May 2025 15:57:38 +0800 (CST) Subject: Re: [PATCH 07/23] md/md-bitmap: delay registration of bitmap_ops until creating bitmap To: Xiao Ni , Yu Kuai Cc: hch@lst.de, colyli@kernel.org, song@kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org, yi.zhang@huawei.com, yangerkun@huawei.com, johnny.chenyi@huawei.com, "yukuai (C)" References: <20250524061320.370630-1-yukuai1@huaweicloud.com> <20250524061320.370630-8-yukuai1@huaweicloud.com> From: Yu Kuai Message-ID: <12a61dcf-ad39-48e8-132f-c49979b9012b@huaweicloud.com> Date: Mon, 26 May 2025 15:57:37 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.1 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-CM-TRANSID:gCh0CgAni1_xHjRoDfE2Ng--.33568S3 X-Coremail-Antispam: 1UD129KBjvJXoW7ZryUArWxuF1UtF1fKr15urg_yoW8tF45p3 yfJ3W3CF4fXrWIqw13Xa4DuF9Ygw4kJrZFvryIqw1rGrnrCrnxAFWFg3WFyry8A3WS9F1q vr15Jr18G34j9FJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBF14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26F1j6w1UM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gc CE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E 2Ix0cI8IcVAFwI0_JrI_JrylYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvEwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lFIxGxcIEc7CjxVA2Y2ka 0xkIwI1lc7I2V7IY0VAS07AlzVAYIcxG8wCY1x0262kKe7AKxVWUtVW8ZwCF04k20xvY0x 0EwIxGrwCFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E 7480Y4vE14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcV C0I7IYx2IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcVCF 04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7 CjxVAFwI0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JUZYFZUUUUU= X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ Hi, 在 2025/05/26 14:52, Xiao Ni 写道: > On Sat, May 24, 2025 at 2:18 PM Yu Kuai wrote: >> >> From: Yu Kuai >> >> Currently bitmap_ops is registered while allocating mddev, this is fine >> when there is only one bitmap_ops, however, after introduing a new >> bitmap_ops, user space need a time window to choose which bitmap_ops to >> use while creating new array. > > Could you give more explanation about what the time window is? Is it > between setting llbitmap by bitmap_type and md_bitmap_create? The window after this patch is that user can write the new sysfs after allocating mddev, and before running the array. > >> >> Signed-off-by: Yu Kuai >> --- >> drivers/md/md.c | 86 +++++++++++++++++++++++++++++++------------------ >> 1 file changed, 55 insertions(+), 31 deletions(-) >> >> diff --git a/drivers/md/md.c b/drivers/md/md.c >> index 4eb0c6effd5b..dc4b85f30e13 100644 >> --- a/drivers/md/md.c >> +++ b/drivers/md/md.c >> @@ -674,39 +674,50 @@ static void no_op(struct percpu_ref *r) {} >> >> static bool mddev_set_bitmap_ops(struct mddev *mddev) >> { >> + struct bitmap_operations *old = mddev->bitmap_ops; >> + struct md_submodule_head *head; >> + >> + if (mddev->bitmap_id == ID_BITMAP_NONE || >> + (old && old->head.id == mddev->bitmap_id)) >> + return true; >> + >> xa_lock(&md_submodule); >> - mddev->bitmap_ops = xa_load(&md_submodule, mddev->bitmap_id); >> + head = xa_load(&md_submodule, mddev->bitmap_id); >> xa_unlock(&md_submodule); >> >> - if (!mddev->bitmap_ops) { >> - pr_warn_once("md: can't find bitmap id %d\n", mddev->bitmap_id); >> + if (WARN_ON_ONCE(!head || head->type != MD_BITMAP)) { >> + pr_err("md: can't find bitmap id %d\n", mddev->bitmap_id); >> return false; >> } >> >> + if (old && old->group) >> + sysfs_remove_group(&mddev->kobj, old->group); > > I think you're handling a competition problem here. But I don't know > how the old/old->group is already created when creating an array. > Could you explain this? It's not possible now, this is because I think we want to be able to switch existing array with old bitmap to new bitmap. Thanks, Kuai > > Regards > Xiao