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 0E74F235041; Mon, 25 Aug 2025 09:36:07 +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=1756114571; cv=none; b=LwCCv+7tgLcm99ALKaxhP0l1A4/qGeaPDFRA4pna2xC63c4KZ10rsIZuYarQp6KPeKeEyyALSwWZ5XBig7Ea/NwwWZGOKZM8pqU7q7IQgLKNwYssvdRCh1SKljn2jMsjSzhQH3V0Ikanv+1Qbmm/SBauynGDgAFdYt15e7e5HFw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756114571; c=relaxed/simple; bh=N9qWtkRk3fJ5bIXuhkjNCG48R1vPFV+wVc1tIXHExks=; h=Subject:To:Cc:References:From:Message-ID:Date:MIME-Version: In-Reply-To:Content-Type; b=UxVPPP/+TgFLLYSw0Q1gzBwBLpyn9/7YS8wlPmuNbAZ5qcrZGxX/ESsa6wYqa/DMMa4WG7yx9+u0sdWE57p/DE7PK1x+/lPG9aREbZ8Dra6Fx0OzZX3nOILLxAHhDbKonhBGQaryEZV+0BFmjq5IQLR3bi++Jy32QANl3S4oJDY= 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 [172.19.163.216]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTPS id 4c9Qdy2sppzYQtnt; Mon, 25 Aug 2025 17:36:06 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id E9F391A01A1; Mon, 25 Aug 2025 17:36:04 +0800 (CST) Received: from [10.174.179.143] (unknown [10.174.179.143]) by APP4 (Coremail) with SMTP id gCh0CgAXYIyCLqxo09rwAA--.44762S3; Mon, 25 Aug 2025 17:36:04 +0800 (CST) Subject: Re: [PATCH] loop: fix zero sized loop for block special file To: Christoph Hellwig , Ming Lei Cc: Yu Kuai , axboe@kernel.dk, rajeevm@hpe.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yi.zhang@huawei.com, yangerkun@huawei.com, johnny.chenyi@huawei.com, linux-fsdevel@vger.kernel.org, "yukuai (C)" References: <20250825062300.2485281-1-yukuai1@huaweicloud.com> From: Yu Kuai Message-ID: Date: Mon, 25 Aug 2025 17:36:02 +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-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=gbk; format=flowed Content-Transfer-Encoding: 8bit X-CM-TRANSID:gCh0CgAXYIyCLqxo09rwAA--.44762S3 X-Coremail-Antispam: 1UD129KBjvdXoWruF48CrWrCF1fKw4xAF43Jrb_yoWftrb_Wr 1rAFyDt348Zrn2k3y3K3WDtrZ5GF4jkry3X3y0kF9Fywn7X34fuF1rZ343WF12qryjyrsI 9w43Zr1UJry3ujkaLaAFLSUrUUUUjb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUIcSsGvfJTRUUUbfAFF20E14v26r4j6ryUM7CY07I20VC2zVCF04k26cxKx2IYs7xG 6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8w A2z4x0Y4vE2Ix0cI8IcVAFwI0_tr0E3s1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j 6F4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oV Cq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0 I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r 4UM4x0Y48IcVAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2kI c2xKxwCYjI0SjxkI62AI1cAE67vIY487MxkF7I0En4kS14v26r1q6r43MxAIw28IcxkI7V AKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCj r7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y0x0EwIxGrwCI42IY6x IIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAI w20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x 0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7VUbGQ6JUUUUU== X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ Hi, ÔÚ 2025/08/25 17:18, Christoph Hellwig дµÀ: > On Mon, Aug 25, 2025 at 04:56:55PM +0800, Ming Lei wrote: >> `stat $BDEV_PATH` never works for getting bdev size, so it looks wrong >> to call vfs_getattr_nosec() with bdev path for retrieving bdev's size. > > Exactly. > Ok. >> So just wondering why not take the following more readable way? >> >> /* vfs_getattr() never works for retrieving bdev size */ >> if (S_ISBLK(stat.mode)) { >> loopsize = i_size_read(file->f_mapping->host); >> } else { >> ret = vfs_getattr_nosec(&file->f_path, &stat, STATX_SIZE, 0); >> if (ret) >> return 0; >> loopsize = stat.size; >> } Just we can't use stat.mode here, I'll replace it with: S_ISBLK(file_inode(file)->i_mode) Thanks, Kuai >> >> Also the above looks like how application reads file size in case of bdev >> involved. > > That's not just more readable, but simply the way to go. Maybe split > it into a helper for readability, though. > . >