Received-SPF: pass (google.com: domain of linux-kernel+bounces-42476-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Message-ID: <ca58facd-db6b-42b2-ace3-595817c81ca9@oracle.com>
Date: Mon, 29 Jan 2024 09:36:38 +0000
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH v3 15/15] nvme: Ensure atomic writes will be executed
 atomically
Content-Language: en-US
To: Christoph Hellwig <hch@lst.de>, martin.petersen@oracle.com
Cc: Keith Busch <kbusch@kernel.org>, axboe@kernel.dk, sagi@grimberg.me,
        jejb@linux.ibm.com, djwong@kernel.org, viro@zeniv.linux.org.uk,
        brauner@kernel.org, dchinner@redhat.com, jack@suse.cz,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-nvme@lists.infradead.org, linux-xfs@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, tytso@mit.edu, jbongio@google.com,
        linux-scsi@vger.kernel.org, ming.lei@redhat.com, ojaswin@linux.ibm.com,
        bvanassche@acm.org, Alan Adamson <alan.adamson@oracle.com>
References: <20240124113841.31824-1-john.g.garry@oracle.com>
 <20240124113841.31824-16-john.g.garry@oracle.com>
 <ZbGwv4uFdJyfKtk5@kbusch-mbp.dhcp.thefacebook.com>
 <dbb3ad13-7524-4861-8006-b2ea426fbacd@oracle.com>
 <20240129062035.GB19796@lst.de>
From: John Garry <john.g.garry@oracle.com>
Organization: Oracle Corporation
In-Reply-To: <20240129062035.GB19796@lst.de>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: 
	=?utf-8?B?VUY5ZFl0eDgxMUFucjBvekxPbm9XaXhreGxyMlNwV3QwVlMrYlBqaTI1UWph?=
 =?utf-8?B?NFdYWEllTy9qOGZjVmlsWVhHMFhBbStWQml4R1NrQ2dCQm4zcUFiSytPOEtJ?=
 =?utf-8?B?ZlI0OU5BVE0zZnRNOFZaZGMyTjFTdHJkeng3SVE3c2I2dmVzUmltUHQ5cnB3?=
 =?utf-8?B?M3E3b2dIUTk1YWRXV0lnRDk4TDhCdG1xN252cmJ1QStnbDk3RG5tUEhoV010?=
 =?utf-8?B?emN2RXg3ZTg5K1k5QVh1Zyt6YVpnTmhCTzhXWjZnMDNuTUpkUVllS0xIdStQ?=
 =?utf-8?B?eHI1K3JCWG53Nm9MeSswRzNJcEU3MXZsU0NjOVVNMWZCYmhTUGk4RER5aERR?=
 =?utf-8?B?QTNaUzY5bXpEUm1FQkh0UzhjU3dFRDcwY21IcTFlNkJHbSsxZjY3aGt0bkFG?=
 =?utf-8?B?Kys3eDgwcWF3cEtOd3V1dVlCeGErN2h4Znh6TENSdDh4cGlLVlRjVlFDMGg0?=
 =?utf-8?B?bWxHcTExRFBlNWVubWxkMHVtS0YzNDNMaVFsVTRCYkkwRlN6QkJHSC9GaWdJ?=
 =?utf-8?B?dElRNzlhOUg1SHNjUldDaTZvUUZVWkdFQzBreHg4QU9BMjJUL3dyZ0NweFRH?=
 =?utf-8?B?dmx5YlZEcitxSnlReTZnR1VFZWY3TEtiVjBjRUVoeHcrNWp2cnNZdUp6Ly9O?=
 =?utf-8?B?MDZDTEhnd1Z6OGMvaGxyRzlLRUlLSHpnYVM4WWdRNElSdkhMVzdXTG9MWVI4?=
 =?utf-8?B?T2JXVXFGVkc2Sk84RlM3VS9wL01BS3pqZE1HRkJJRjNjT2JHUFVBT3krcFJy?=
 =?utf-8?B?UHl2MWp6RUhNZCtTc2xXMm94RmpacmNzWWs0Rk5hNDh0MEx2ekpZZk54NWRL?=
 =?utf-8?B?Z2RZTGQ3UXNxbHhrSnpmQkZTdUc1b1krdExZWjVIMTYxT0MrVjRGRzJBdnVi?=
 =?utf-8?B?S2x1NnNwWlFNbmVNMVRobXlkUDZhbWo0aVdaZm5abit6V0o4aEl1UUgxa1VD?=
 =?utf-8?B?b2F4Skt2dFFWd00xNldyTy80Wjc0TFVCMXMyaDZWbjlaWGhkYVdHc2U1M2Uz?=
 =?utf-8?B?M1Y2TjQxUUY2VGhKQjlRaWd1bmwrOHdWMDB1Q0wvVjhoTzlQcDQ1RmZweTFF?=
 =?utf-8?B?MjFGR0k0bzZ6bWlvQXpIc0JOMWRGREtBbCtBS3NrR3VOWDd6WVVlSFB3UGpD?=
 =?utf-8?B?TEVXaDZQZ2c3LzhZWjVaK0hkeXFNaW5GRW1VM0IwektkU0ZRNzVBOUxyL0Rz?=
 =?utf-8?B?SXk0azBFcndTQUprbkx2bldpUWh0TFpZWEtmUGkwRHo5MXIwVXZjOEhGVHBo?=
 =?utf-8?B?YktkK3JEeVlVeXRJQnlHZ3NGSWpJOUdJRnBWdmNjU3dZd1dGTGQySWYxeU45?=
 =?utf-8?B?Q05ZVjRDeXdZemFSUkRXdDZ3Rm1XL3hmalZ5S2R6ODJaYjBHK3ROOG1tbnpK?=
 =?utf-8?B?REh2Qzc2NHZRb2lnT01TN253Y3pzelNOV29zcDhMY3NJV1orVU9KZkJmVU5q?=
 =?utf-8?B?Z2VsUXk1V0tIb1MxUnNEa3FEUW4ydUVYdk9veGFZbHJuaWs0TVZwZkUyaldw?=
 =?utf-8?B?UGVpVjJIUmNaV0Y1anRNSEVoeG5XQTRxejBRcmZEL1N0M1E1OW85VU5HUHBY?=
 =?utf-8?B?RVdER3ZqZ3V3TlBDUytCRkRPcGEwdHlFb1VOdWR1WWR5cEcrTG5wYjNScm1i?=
 =?utf-8?B?V2FrWWZvTUhrQ0FlaHA3TVBjZnJqeUg4QTFHYURYV3hxanVXL2REN1pCMTF6?=
 =?utf-8?B?ak4zSGZNOC9rZnhKOHk4bVJjRVBGQXFQTnFwWWFPWnRtOWRreW05NTNTMWpa?=
 =?utf-8?B?QjUra2ZHRlNGcTRGR0syZmM4aTUxVVdkY3ljM08xUEFmMVFvbVYxUnhhK2NH?=
 =?utf-8?B?eFpYNHJ3NEdkQkFQbGl3WnBDMWZTdEM2Rk9rUFlqcUZNSStLNFpmM3ZxQzZB?=
 =?utf-8?B?Uk51MkFRYzYxREh2UURVeVptRlZsRklQbkQyTHI4RHhaZmpZbno3TW8rWDJW?=
 =?utf-8?B?NUxZdExuU0krZWVQL3ZmYTZBaUJpV0xwK3hkMmxESGdRenRHZCtzRHl3dlo3?=
 =?utf-8?B?azZjTVh6K1hjQktTS2tBUGxzS3RNSkN5b2l2N1BTMHlQcUJxK0dPMUw3Q2xy?=
 =?utf-8?B?UnJxR1JKQWhGZTYyVS9KdEZkc0ZBckxOSjlnNy9rVmV4Zk1sMyt4dGVWL3lO?=
 =?utf-8?B?U1Z1a0ZHSHFOUkcraTNac2cxR2tQTVpDQllDSDVWQnpmQldxWGVOVFkwV1E3?=
 =?utf-8?B?WlE9PQ==?=
X-MS-Exchange-AntiSpam-ExternalHop-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-ExternalHop-MessageData-0: 
	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
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 553dec13-ea2d-427f-d533-08dc20adcd17
X-MS-Exchange-CrossTenant-AuthSource: DM6PR10MB4313.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 29 Jan 2024 09:36:42.4250
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: L9ZpKp7RAThhXtQBAvfdTQfKw08Nga2wjlh1JWp8LZzOv+wBj18S2NWWihxCjnbQnJifJNp1dTbRzek2UHdlyw==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR10MB6822
X-Proofpoint-Virus-Version: vendor=baseguard
 engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26
 definitions=2024-01-29_05,2024-01-25_01,2023-05-22_02
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 phishscore=0 bulkscore=0 malwarescore=0
 mlxscore=0 mlxlogscore=999 spamscore=0 adultscore=0 suspectscore=0
 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000
 definitions=main-2401290068
X-Proofpoint-ORIG-GUID: g6MveXtASMGshKV6IROfZwNw4LsV-d29
X-Proofpoint-GUID: g6MveXtASMGshKV6IROfZwNw4LsV-d29

On 29/01/2024 06:20, Christoph Hellwig wrote:
> On Thu, Jan 25, 2024 at 11:28:22AM +0000, John Garry wrote:
>> We have limits checks in XFS iomap and fops.c, but we would also want to
>> ensure that the the block layer is not doing anything it shouldn't be doing
>> after submit_bio_noacct(), like merging atomic write BIOs which straddle a
>> boundary or exceed atomic_max (if there were any merging).
>>
>> The SCSI standard already has provision for error'ing an atomic write
>> command which exceeds the target atomic write capabilities, while NVMe
>> doesn't.
> 
> Can you get Oracle to propose this for NVMe?  It always helps if these
> suggestions come from a large buyer of NVMe equipment.

I'll let Martin comment on that.

> 
>> BTW, Christoph did mention that he would like to see this:
>> https://lore.kernel.org/linux-nvme/20231109153603.GA2188@lst.de/
> 
> I can probably live with a sufficiently low-level block layer check.

That would probably be in blk_mq_dispatch_rq_list() for block drivers 
with .queue_rq set, but I would need to check for a good place for 
->queue_rqs . I can't imagine that we just want to inefficiently iter 
all rqs at the ->queue_rqs call point.

However considering the nature of this change, it is not a good sign 
that we/I need to check... I'd be more inclined to leave as is.

Thanks,
John