From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 617721A3BD7 for ; Fri, 21 Nov 2025 16:48:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763743735; cv=none; b=HLZjubJCo+f4JZZOhO8iS6p3fn2RoJ5Zcq56GiGxeP+rqNvr26v003msCBfAMMR9ZwwfkTRh70GowZAzV12ze/wHLJ+SW08WC/ythNTP9bvPLz0D/3roZ0iUiBqrmBW+Z+KUIy/k5eKRWC1gJV0VhYmYHAsXPGYNYUF06lW4Pvw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763743735; c=relaxed/simple; bh=Py+eUaG7KjKGE2UByt0X5KqgWPv3DKjcfHuHBSO/W5c=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=X+vo+WrEwBlPw3PhoVCwsbBhz7d9qaZl49cSJ+mh/yRXiDLnHRrHDLdTVHHXBQNX3+a9Vh3KLx8ErECN9eQKsW7FM5qadIVSoDqnmJyQVl9y6aoAwT5kDYbWrMylkywJqZmyousoLuNz/vbCOabx9+alvNLYfgdsiPUoWfuBvzw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=UIhtrFuO; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="UIhtrFuO" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1763743732; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=MG7U0FeK78zPIuCL+1OBmvgEb3SpMMFvrUNSSf8ey7M=; b=UIhtrFuOT7K0P89JnMObzMYWMMU/mTcuXs74128s1543JNdSdjsbCnJB++eCC4+1gtlc8P jUOqe8CKxsgzahMGp5tR2kJ6EdbsfQlZlyf/qp981n5o7Z/DqaJCF1JfVDUxPBw6r6PJM+ /VPYqlpvtcApWIAkYypTkOU+fPu3NZQ= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-331-m5j9GWt5OvSX-IuIszzM9A-1; Fri, 21 Nov 2025 11:48:48 -0500 X-MC-Unique: m5j9GWt5OvSX-IuIszzM9A-1 X-Mimecast-MFC-AGG-ID: m5j9GWt5OvSX-IuIszzM9A_1763743727 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 7B7A21800447; Fri, 21 Nov 2025 16:48:47 +0000 (UTC) Received: from bmarzins-01.fast.eng.rdu2.dc.redhat.com (unknown [10.6.23.247]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 75A6230044E7; Fri, 21 Nov 2025 16:48:46 +0000 (UTC) Received: from bmarzins-01.fast.eng.rdu2.dc.redhat.com (localhost [127.0.0.1]) by bmarzins-01.fast.eng.rdu2.dc.redhat.com (8.18.1/8.17.1) with ESMTPS id 5ALGmjDK1021652 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Fri, 21 Nov 2025 11:48:45 -0500 Received: (from bmarzins@localhost) by bmarzins-01.fast.eng.rdu2.dc.redhat.com (8.18.1/8.18.1/Submit) id 5ALGmiAl1021651; Fri, 21 Nov 2025 11:48:44 -0500 Date: Fri, 21 Nov 2025 11:48:44 -0500 From: Benjamin Marzinski To: Uladzislau Rezki Cc: Christoph Hellwig , Mikulas Patocka , Alasdair Kergon , DMML , Andrew Morton , Mike Snitzer , LKML Subject: Re: [RESEND PATCH] dm-ebs: Mark full buffer dirty even on partial write Message-ID: References: <73556fc8-5fbf-37cb-26b9-7cdb88f69720@redhat.com> <230baa83-cd79-f232-5fb8-1476115e1ae7@redhat.com> <20251119054635.GB19993@lst.de> <20251120062146.GA29990@lst.de> <20251121072421.GA29754@lst.de> Precedence: bulk X-Mailing-List: dm-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 On Fri, Nov 21, 2025 at 02:21:34PM +0100, Uladzislau Rezki wrote: > On Fri, Nov 21, 2025 at 08:24:21AM +0100, Christoph Hellwig wrote: > > On Thu, Nov 20, 2025 at 01:08:57PM +0100, Uladzislau Rezki wrote: > > > Could you please check below? Is the last one is correctly reported? > > > > The latter looks unexpected, but is is becase qemu is not passing through > > the qemu physical_block_size attribute to any of the nvme settings Linux > > interprets as such for NVMe (NVMe doesn't actually have the concept of > > a physical block size, unlike SCSI/ATA): > > > OK, understood and thank you for checking this. > > > > > root@testvm:~# nvme id-ns -H /dev/nvme0n1 | grep npw > > npwg : 0 > > npwa : 0 > > root@testvm:~# nvme id-ns -H /dev/nvme0n1 | grep naw > > nawun : 0 > > nawupf : 0 > > root@testvm:~# nvme id-ctrl -H /dev/nvme0 | grep awupf > > awupf : 0 > > > > but as said multiple times, that should not really matter - the logical > > block size is the granularity of I/O, the physical block size is just > > a performance hint. > > > Right. > > As stated in commit message of the patch which is in question. 8K > emulated in qemu device with CONFIG_TRANSPARENT_HUGEPAGE=y: > > urezki@pc638:~$ sudo nvme list > Node Generic SN Model Namespace Usage Format FW Rev > --------------------- --------------------- -------------------- ---------------------------------------- --------- -------------------------- ---------------- -------- > /dev/nvme0n1 /dev/ng0n1 foo QEMU NVMe Ctrl 1 8.49 GB / 8.49 GB 8 KiB + 0 B 10.0.6 > urezki@pc638:~$ cat bin/dmsetup.sh > #!/bin/bash > > lower=/dev/nvme0n1 > len=$(blockdev --getsz "$lower") > > echo "0 $len ebs $lower 0 1 16" | dmsetup create nvme-8k > urezki@pc638:~$ sudo bin/dmsetup.sh > urezki@pc638:~$ sudo cat /sys/block/nvme0n1/queue/logical_block_size > 8192 > urezki@pc638:~$ sudo cat /sys/block/nvme0n1/queue/physical_block_size > 8192 > urezki@pc638:~$ sudo cat /sys/block/dm-0/queue/logical_block_size > 512 > urezki@pc638:~$ sudo cat /sys/block/dm-0/queue/physical_block_size > 8192 > urezki@pc638:~$ sudo mkfs.ext4 -F /dev/dm-0 > mke2fs 1.47.0 (5-Feb-2023) > /dev/dm-0 contains a ext4 file system > last mounted on Fri Nov 21 12:22:55 2025 > Discarding device blocks: done > Creating filesystem with 2072576 4k blocks and 518144 inodes > Filesystem UUID: f71adb05-c020-4406-bc0d-bdb9e5c29af7 > Superblock backups stored on blocks: > 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632 > > Allocating group tables: done > Writing inode tables: done > Creating journal (16384 blocks): done > Writing superblocks and filesystem accounting information: mkfs.ext4: Input/output error while writing out and closing file system > urezki@pc638:~$ sudo dmesg | grep -i "i/o" > [ 71.813322] Buffer I/O error on dev dm-0, logical block 10, lost async page write > [ 71.813373] Buffer I/O error on dev dm-0, logical block 11, lost async page write > [ 71.813395] Buffer I/O error on dev dm-0, logical block 12, lost async page write > [ 71.813415] Buffer I/O error on dev dm-0, logical block 13, lost async page write > [ 71.813433] Buffer I/O error on dev dm-0, logical block 14, lost async page write > [ 71.813451] Buffer I/O error on dev dm-0, logical block 15, lost async page write > [ 71.813475] Buffer I/O error on dev dm-0, logical block 16, lost async page write > [ 71.813493] Buffer I/O error on dev dm-0, logical block 17, lost async page write > [ 71.813516] Buffer I/O error on dev dm-0, logical block 18, lost async page write > [ 71.813537] Buffer I/O error on dev dm-0, logical block 19, lost async page write > urezki@pc638:~$ > > with the patch: > > urezki@pc638:~$ sudo nvme list > Node Generic SN Model Namespace Usage Format FW Rev > --------------------- --------------------- -------------------- ---------------------------------------- --------- -------------------------- ---------------- -------- > /dev/nvme0n1 /dev/ng0n1 foo QEMU NVMe Ctrl 1 8.49 GB / 8.49 GB 8 KiB + 0 B 10.0.6 > urezki@pc638:~$ cat bin/dmsetup.sh > #!/bin/bash > > lower=/dev/nvme0n1 > len=$(blockdev --getsz "$lower") > > echo "0 $len ebs $lower 0 1 16" | dmsetup create nvme-8k > urezki@pc638:~$ sudo bin/dmsetup.sh > urezki@pc638:~$ sudo cat /sys/block/nvme0n1/queue/logical_block_size > 8192 > urezki@pc638:~$ sudo cat /sys/block/nvme0n1/queue/physical_block_size > 8192 > urezki@pc638:~$ sudo cat /sys/block/dm-0/queue/logical_block_size > 512 > urezki@pc638:~$ sudo cat /sys/block/dm-0/queue/physical_block_size > 8192 > urezki@pc638:~$ sudo mkfs.ext4 -F /dev/dm-0 > mke2fs 1.47.0 (5-Feb-2023) > Discarding device blocks: done > Creating filesystem with 2072576 4k blocks and 518144 inodes > Filesystem UUID: c7dff4c7-aa7e-4c94-98ee-f9ea2da92a06 > Superblock backups stored on blocks: > 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632 > > Allocating group tables: done > Writing inode tables: done > Creating journal (16384 blocks): done > Writing superblocks and filesystem accounting information: done > > urezki@pc638:~$ sudo mount /dev/dm-0 /mnt/ > urezki@pc638:~$ ls -al /mnt/ > total 24 > drwxr-xr-x 3 root root 4096 Nov 21 12:22 . > drwxr-xr-x 19 root root 4096 Jul 10 19:42 .. > drwx------ 2 root root 16384 Nov 21 12:22 lost+found > urezki@pc638:~$ > > How do we solve this? > > Mikulas proposed to use below patch: > > > Index: linux-2.6/drivers/md/dm-bufio.c > =================================================================== > --- linux-2.6.orig/drivers/md/dm-bufio.c 2025-10-13 21:42:47.000000000 +0200 > +++ linux-2.6/drivers/md/dm-bufio.c 2025-10-20 14:40:32.000000000 +0200 > @@ -1374,7 +1374,7 @@ static void submit_io(struct dm_buffer * > { > unsigned int n_sectors; > sector_t sector; > - unsigned int offset, end; > + unsigned int offset, end, align; > > b->end_io = end_io; > > @@ -1388,9 +1388,10 @@ static void submit_io(struct dm_buffer * > b->c->write_callback(b); > offset = b->write_start; > end = b->write_end; > - offset &= -DM_BUFIO_WRITE_ALIGN; > - end += DM_BUFIO_WRITE_ALIGN - 1; > - end &= -DM_BUFIO_WRITE_ALIGN; > + align = max(DM_BUFIO_WRITE_ALIGN, bdev_logical_block_size(b->c->bdev)); > + offset &= -align; > + end += align - 1; > + end &= -align; > if (unlikely(end > b->c->block_size)) > end = b->c->block_size; > > > and it fixes the setup which i described in the commit message, but i > have question. > > Why in dm-ebs we need to offload partial buffer < ubf size? Um, did you notice that Mikulas accepted your patch? > > Thank you for answers! > > -- > Uladzislau Rezki