From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (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 BB9BB277021; Tue, 6 May 2025 11:25:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746530713; cv=none; b=EBlpECZN2/bM5Lbi10xw8fAcnlDPfy3nuexXmzRb2jNtTucg8ldd3suvRunOn6Y0hHhhL6Q1245gLJTHSoMDqlquVb3nEr1ZEmCCWAlTgylcmwQzWC8QP6fMSfj4Hf8zZtGxxnC6Hwb+ECWR+ZfwGBBqAMndgQIfsO9dGbJPh/o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1746530713; c=relaxed/simple; bh=LYEoDqW9Aw3HirRWc3fZPPqmXKbhw5VH1R/eJ7s7ey0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=DbaBIHPJLzFbldzhHAqlBiBjSiWaKpArC6BKQDNIJYQ4+Kzlr0I6qBUl0rxqjB8vC5YvAOPZi2kDUmXL2eucqao6UKj0Vk/IohWmvbSaYh/v2jdLkdg9lwlIXiiPljz3toxtkcuirU+D4aPbHYLh4lRgo+aKmEBeGshUfzZ1R9I= 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=45.249.212.51 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 dggsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4ZsGK03YjSzYQv9t; Tue, 6 May 2025 19:25:08 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id D0A9F1A1041; Tue, 6 May 2025 19:25:07 +0800 (CST) Received: from [10.174.179.80] (unknown [10.174.179.80]) by APP4 (Coremail) with SMTP id gCh0CgD3Wl+S8RlowhVpLg--.31381S3; Tue, 06 May 2025 19:25:07 +0800 (CST) Message-ID: Date: Tue, 6 May 2025 19:25:06 +0800 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v4 07/11] fs: statx add write zeroes unmap attribute To: Christoph Hellwig , "Darrick J. Wong" Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-block@vger.kernel.org, dm-devel@lists.linux.dev, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu, john.g.garry@oracle.com, bmarzins@redhat.com, chaitanyak@nvidia.com, shinichiro.kawasaki@wdc.com, brauner@kernel.org, yi.zhang@huawei.com, chengzhihao1@huawei.com, yukuai3@huawei.com, yangerkun@huawei.com References: <20250421021509.2366003-1-yi.zhang@huaweicloud.com> <20250421021509.2366003-8-yi.zhang@huaweicloud.com> <20250505132208.GA22182@lst.de> <20250505142945.GJ1035866@frogsfrogsfrogs> <20250506050239.GA27687@lst.de> <20250506053654.GA25700@frogsfrogsfrogs> <20250506054722.GA28781@lst.de> Content-Language: en-US From: Zhang Yi In-Reply-To: <20250506054722.GA28781@lst.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-CM-TRANSID:gCh0CgD3Wl+S8RlowhVpLg--.31381S3 X-Coremail-Antispam: 1UD129KBjvJXoW7tr4rXrW8WF4fKryrZw43ZFb_yoW8GF47pF WkCFyIkr4IkF47Ga1kZw1Ivr1Y9rn7JFy7C3s5Kr12yay2qrn7uFn5Ca42kFnaqr93uw4Y qFZxX342va1093DanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvYb4IE77IF4wAFF20E14v26ryj6rWUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr1j6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x 0267AKxVW0oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG 6I80ewAv7VC0I7IYx2IY67AKxVWUGVWUXwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFV Cjc4AY6r1j6r4UM4x0Y48IcVAKI48JM4IIrI8v6xkF7I0E8cxan2IY04v7MxkF7I0En4kS 14v26r4a6rW5MxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I 8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVW8ZVWr XwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x 0267AKxVW8JVWxJwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_ Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVW8Jr0_Cr1UYxBIdaVFxhVjvjDU0xZFpf9x07 j7l19UUUUU= X-CM-SenderInfo: d1lo6xhdqjqx5xdzvxpfor3voofrz/ On 2025/5/6 13:47, Christoph Hellwig wrote: > On Mon, May 05, 2025 at 10:36:54PM -0700, Darrick J. Wong wrote: >> I think STATX_* (i.e. not STATX_ATTR_*) flags have two purposes: 1) to >> declare that specific fields in struct statx actually have meaning, most >> notably in scenarios where zeroes are valid field contents; and 2) if >> filling out the field is expensive, userspace can elect not to have it >> filled by leaving the bit unset. I don't know how userspace is supposed >> to figure out which fields are expensive. > > Yes. > IIUC, it seems I was misled by STATX_ATTR_WRITE_ATOMIC, adding this STATX_ATTR_WRITE_ZEROES_UNMAP attribute flag is incorrect. The right approach should be to add STATX_WRITE_ZEROES_UNMAP, setting it in the result_mask if the request_mask includes this flag and bdev_write_zeroes_unmap(bdev) returns true. Something like below. Is my understanding right? diff --git a/block/bdev.c b/block/bdev.c index 4ba48b8735e7..e1367f30dbce 100644 --- a/block/bdev.c +++ b/block/bdev.c @@ -1303,9 +1303,9 @@ void bdev_statx(const struct path *path, struct kstat *stat, u32 request_mask) queue_atomic_write_unit_max_bytes(bd_queue)); } + if (request_mask & STATX_WRITE_ZEROES_UNMAP && + bdev_write_zeroes_unmap(bdev)) + stat->result_mask |= STATX_WRITE_ZEROES_UNMAP; stat->blksize = bdev_io_min(bdev); Thanks, Yi.