Received-SPF: pass (google.com: domain of linux-nfs-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
Message-ID: <5a42bf04-3f79-b0e2-7ee3-9a5bfad72990@oracle.com>
Date:   Tue, 15 Mar 2022 23:29:23 -0700
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0)
 Gecko/20100101 Thunderbird/91.7.0
Subject: Re: [PATCH RFC v16 05/11] NFSD: Update nfs4_get_vfs_file() to handle
 courtesy clients
Content-Language: en-US
To:     "J. Bruce Fields" <bfields@fieldses.org>
Cc:     chuck.lever@oracle.com, jlayton@redhat.com,
        viro@zeniv.linux.org.uk, linux-nfs@vger.kernel.org,
        linux-fsdevel@vger.kernel.org
References: <1647051215-2873-1-git-send-email-dai.ngo@oracle.com>
 <1647051215-2873-6-git-send-email-dai.ngo@oracle.com>
 <20220315153928.GC19168@fieldses.org>
From:   dai.ngo@oracle.com
In-Reply-To: <20220315153928.GC19168@fieldses.org>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?L3dXcXdtSjRNOTEvdGNzbzAvbW56QkJvUjNOL1pJM2lTcFM1ZkhOU1haYUFx?=
 =?utf-8?B?VVA1aVlJTHdoYzNSUTUzNjNvK01jenN2c3ladUJXOW9ubW1JQkdHNVJ5VW9V?=
 =?utf-8?B?RHZBdUJTVkFEQVBCY3VPZUZwM251eElJbzJ6TVhZUWJEdFk4blphaWM3OHdJ?=
 =?utf-8?B?U2V4Yi9QcjcrS3hTbGU3aEwxWkduQWxNYWo5emFsMlpCL3RjY0lSZ1RFUEto?=
 =?utf-8?B?eEx6cFJ0VjdiTWVFdjhlcXZhUUlCMks3Z3grcklIUHdQNlU1ZjVrdXcwWHlM?=
 =?utf-8?B?NDIwY0hMYTJjWml6WUpvbHJRVk9BcjZlQkdFdGxpQnp4M1dJMnJpRHRhODZ5?=
 =?utf-8?B?alE4VGpndzNDU3FnYTVkVUZyd1AyUUwwQjdlY3BjNldTL0pMUUEvZUhXeHhJ?=
 =?utf-8?B?UnNBa1ltdTVWcDRWb2JtRWJ0MGxaNk50Q00wTnZ1VjQ0di95VDFLL0xseElP?=
 =?utf-8?B?bitQVU5iZmFXWWE4VFlBQ3drN1lubFRpWmo2N0dtSlZhQVRGRDNGeWJCNVJ0?=
 =?utf-8?B?aEp4a3RGTlo4YzZvaTZqeTVIMXVVTFNXUTBlQmlENVYwd29XUVJQSnovSzZR?=
 =?utf-8?B?WUxKQjNPQ3FCQk1WWDhtSFNmK3MzM1dRZEdZOUlHamNubUJvMFYyMHFLalM4?=
 =?utf-8?B?RStZSG4yYjdKUW5Kc1h1YXNlQVZ6TzgzZ2JIREM4akRleFB0Zm5ibFk4NC92?=
 =?utf-8?B?OFRLN1R0RDJUalZYMU1DdFNEdllaTHBCWnpZYmJrUXNTVXhpOUpHdUJBRjVZ?=
 =?utf-8?B?ZmZaakNpUDU5a2s1UHFxTHFWTktQZmZ4am84eDl4V2pNcTgxRTYvRHM3ZVRs?=
 =?utf-8?B?VXJPbFJMMDlkWmVaeHVpUHVKVldGN0puc2dSMmpOajExMEI4U05rMU1YOFIr?=
 =?utf-8?B?eUhtb1N1MmhCK0p5M0FreHZ6cnZPNklzV3Y2V1JCUGNabmpoQ2Jra3M1MzVy?=
 =?utf-8?B?N25xcmdQWDVpMEVMaGpKVTRvV3pPb1FOZURkY3M5eURHd0poN3R5ZFltNk9x?=
 =?utf-8?B?RDJnOXhZQTgvZjA2MXJBYko3eVFmSHV5ZEJNUG80R0pTM3hvcEE2M0wzdzRm?=
 =?utf-8?B?d0djbHg0Yk1YbVN6bTEvVmpSMC9pNkQwK3lYZW1CY1pzYXlJZ3VhcWVJYyt3?=
 =?utf-8?B?aWM3Nm9VOWJEU2oyUU4vWC9VV1dCTXp0cDdiTU9ZNVRpOUtJTm9rVjlQZFRz?=
 =?utf-8?B?c3hrWVU2cFIyU3NVYXgrWVUzNjNxNEs5TUhoZ2ZFV251QXlEWXkzbW96K2t2?=
 =?utf-8?B?dUFLSTNiQ2k2amw0R3J4U3ltZ0RDVnNPWElha1N4UGtpaXg0cGdUUyt6czQv?=
 =?utf-8?B?SUxTSE1rWXJvYzlYUzdWVWVjVUFKS3hxcmM4OVBIdDFCeTNIVGl0aEwyZzNq?=
 =?utf-8?B?cllGRHE1SE81ZmRxcmZhUU51TTMzYVhGeHNWWUdWVTBtMXplWmoyR1BGQjVh?=
 =?utf-8?B?TU8vSFZiQnY4SEFzUlpNWitkNXBvTGttV2J1T0VWalJJOG5ZZ2VkQzdCYWJC?=
 =?utf-8?B?V09saTJVMWVxMmlUVUc0MmV6enREVERXMkh1QlNWa2lOYytHME04QTNJWWto?=
 =?utf-8?B?eWhxNUdxTjJ6S1NuUENvQ1l5ZGhXWXZNMXJEVlJrMWU5M0FHbFdJc1IxTU4z?=
 =?utf-8?B?dVVuU1VHdmZaRlRDWVJQZ1V0M0R0cVo0bTF3YklLTnNsSWJNRzlpMW83QU5T?=
 =?utf-8?B?TnplTzZpc2lwd0ErSXVqOUIxd2JTR2ZVbkxNbGNwajkzNDZqQzZZdENpNm81?=
 =?utf-8?B?SEcyVW8vbjNIVk51bW9LR1R0bUQwVU1yL3UwRG9pUDNFTWZSZDlUaUNMeW5v?=
 =?utf-8?B?VWZUUDFlVGNNT1NXdUlrQVM2S2ZYd3dqc3hBSnpVUnZxN2h3c2pVRnBibnBu?=
 =?utf-8?B?bml4UXZVdkpNdzhmVCtFZGp2bEZvRU9La2c5K3oxMmVSdnZIdUI3SHYzMk9L?=
 =?utf-8?Q?2HYLZLfjT29bBjsWhTYsQyYjDDbTcTe0?=
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-Network-Message-Id: ff3ad171-e71f-4d97-f3ae-08da071651c5
X-MS-Exchange-CrossTenant-AuthSource: BY5PR10MB4257.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Mar 2022 06:29:27.0354
 (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: TU0k4fIzTl4Lfh0zC0SNh5AfYmhfb4aByyPCQubo938CGCCqNuuj4r5eWoCYZ4RhVyGsCQoPoD127IVLdIbYFw==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR10MB4048
X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10287 signatures=693139
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 spamscore=0
 malwarescore=0 adultscore=0 bulkscore=0 mlxscore=0 mlxlogscore=999
 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1
 engine=8.12.0-2202240000 definitions=main-2203160040
X-Proofpoint-GUID: RshPTNYhGE90bMLxDhZ7FhsJv52CyA1l
X-Proofpoint-ORIG-GUID: RshPTNYhGE90bMLxDhZ7FhsJv52CyA1l
X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED,
	DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,
	MAILING_LIST_MULTI,NICE_REPLY_A,RDNS_NONE,SPF_HELO_NONE,
	T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
	lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-nfs.vger.kernel.org>
X-Mailing-List: linux-nfs@vger.kernel.org


On 3/15/22 8:39 AM, J. Bruce Fields wrote:
> On Fri, Mar 11, 2022 at 06:13:29PM -0800, Dai Ngo wrote:
>> Update nfs4_get_vfs_file and nfs4_upgrade_open to handle share
>> reservation conflict with courtesy client.
>>
>> If share/access check fails with share denied then check if the
>> the conflict was caused by courtesy clients. If that's the case
>> then set CLIENT_EXPIRED flag to expire the courtesy clients and
>> allow nfs4_get_vfs_file to continue. Client with CLIENT_EXPIRED
>> is expired by the laundromat.
> I'm not following this code.  I'll see if I can give it another shot
> tomorrow, but are you sure it can't be simplified somehow?

When we have deny/access conflict we walk the fi_stateids of the
file in question, looking for open stateid and check the deny/access
of that stateid against the one from the open request. If there is
a conflict then we check if the client that owns that stateid is
a courtesy client. If it is then we set the client state to
CLIENT_EXPIRED and allow the open request to continue. We have
to scan all the stateid's of the file since the conflict can be
caused by multiple open stateid's.

>
> Keep in mind, we really don't care about share conflicts much.  I'm not
> sure whether anyone actually uses open deny modes, so there's no need to
> optimize that case.

Yes, but we have to pass pynfs 4.0 tests.

>   I'd be totally fine with expiring things
> unnecessarily in the deny mode case, for example.

I have not been able to come up with a simpler solution.

-Dai

>
> --b.
>
>> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
>> ---
>>   fs/nfsd/nfs4state.c | 99 ++++++++++++++++++++++++++++++++++++++++++++++++-----
>>   1 file changed, 91 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>> index 2beb0972de88..b16f689f34c3 100644
>> --- a/fs/nfsd/nfs4state.c
>> +++ b/fs/nfsd/nfs4state.c
>> @@ -4973,9 +4973,75 @@ nfsd4_truncate(struct svc_rqst *rqstp, struct svc_fh *fh,
>>   	return nfsd_setattr(rqstp, fh, &iattr, 0, (time64_t)0);
>>   }
>>   
>> +static bool
>> +nfs4_check_access_deny_bmap(struct nfs4_ol_stateid *stp, u32 access,
>> +			bool share_access)
>> +{
>> +	if (share_access) {
>> +		if (!stp->st_deny_bmap)
>> +			return false;
>> +
>> +		if ((stp->st_deny_bmap & (1 << NFS4_SHARE_DENY_BOTH)) ||
>> +			(access & NFS4_SHARE_ACCESS_READ &&
>> +				stp->st_deny_bmap & (1 << NFS4_SHARE_DENY_READ)) ||
>> +			(access & NFS4_SHARE_ACCESS_WRITE &&
>> +				stp->st_deny_bmap & (1 << NFS4_SHARE_DENY_WRITE))) {
>> +			return true;
>> +		}
>> +		return false;
>> +	}
>> +	if ((access & NFS4_SHARE_DENY_BOTH) ||
>> +		(access & NFS4_SHARE_DENY_READ &&
>> +			stp->st_access_bmap & (1 << NFS4_SHARE_ACCESS_READ)) ||
>> +		(access & NFS4_SHARE_DENY_WRITE &&
>> +			stp->st_access_bmap & (1 << NFS4_SHARE_ACCESS_WRITE))) {
>> +		return true;
>> +	}
>> +	return false;
>> +}
>> +
>> +/*
>> + * Check whether courtesy clients have conflicting access
>> + *
>> + * access:  is op_share_access if share_access is true.
>> + *	    Check if access mode, op_share_access, would conflict with
>> + *	    the current deny mode of the file 'fp'.
>> + * access:  is op_share_deny if share_access is false.
>> + *	    Check if the deny mode, op_share_deny, would conflict with
>> + *	    current access of the file 'fp'.
>> + * stp:     skip checking this entry.
>> + * new_stp: normal open, not open upgrade.
>> + *
>> + * Function returns:
>> + *	true   - access/deny mode conflict with normal client.
>> + *	false  - no conflict or conflict with courtesy client(s) is resolved.
>> + */
>> +static bool
>> +nfs4_resolve_deny_conflicts_locked(struct nfs4_file *fp, bool new_stp,
>> +		struct nfs4_ol_stateid *stp, u32 access, bool share_access)
>> +{
>> +	struct nfs4_ol_stateid *st;
>> +	struct nfs4_client *clp;
>> +	bool conflict = false;
>> +
>> +	lockdep_assert_held(&fp->fi_lock);
>> +	list_for_each_entry(st, &fp->fi_stateids, st_perfile) {
>> +		if (st->st_openstp || (st == stp && new_stp) ||
>> +			(!nfs4_check_access_deny_bmap(st,
>> +					access, share_access)))
>> +			continue;
>> +		clp = st->st_stid.sc_client;
>> +		if (nfs4_check_and_expire_courtesy_client(clp))
>> +			continue;
>> +		conflict = true;
>> +		break;
>> +	}
>> +	return conflict;
>> +}
>> +
>>   static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
>>   		struct svc_fh *cur_fh, struct nfs4_ol_stateid *stp,
>> -		struct nfsd4_open *open)
>> +		struct nfsd4_open *open, bool new_stp)
>>   {
>>   	struct nfsd_file *nf = NULL;
>>   	__be32 status;
>> @@ -4991,15 +5057,29 @@ static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
>>   	 */
>>   	status = nfs4_file_check_deny(fp, open->op_share_deny);
>>   	if (status != nfs_ok) {
>> -		spin_unlock(&fp->fi_lock);
>> -		goto out;
>> +		if (status != nfserr_share_denied) {
>> +			spin_unlock(&fp->fi_lock);
>> +			goto out;
>> +		}
>> +		if (nfs4_resolve_deny_conflicts_locked(fp, new_stp,
>> +				stp, open->op_share_deny, false)) {
>> +			spin_unlock(&fp->fi_lock);
>> +			goto out;
>> +		}
>>   	}
>>   
>>   	/* set access to the file */
>>   	status = nfs4_file_get_access(fp, open->op_share_access);
>>   	if (status != nfs_ok) {
>> -		spin_unlock(&fp->fi_lock);
>> -		goto out;
>> +		if (status != nfserr_share_denied) {
>> +			spin_unlock(&fp->fi_lock);
>> +			goto out;
>> +		}
>> +		if (nfs4_resolve_deny_conflicts_locked(fp, new_stp,
>> +				stp, open->op_share_access, true)) {
>> +			spin_unlock(&fp->fi_lock);
>> +			goto out;
>> +		}
>>   	}
>>   
>>   	/* Set access bits in stateid */
>> @@ -5050,7 +5130,7 @@ nfs4_upgrade_open(struct svc_rqst *rqstp, struct nfs4_file *fp, struct svc_fh *c
>>   	unsigned char old_deny_bmap = stp->st_deny_bmap;
>>   
>>   	if (!test_access(open->op_share_access, stp))
>> -		return nfs4_get_vfs_file(rqstp, fp, cur_fh, stp, open);
>> +		return nfs4_get_vfs_file(rqstp, fp, cur_fh, stp, open, false);
>>   
>>   	/* test and set deny mode */
>>   	spin_lock(&fp->fi_lock);
>> @@ -5059,7 +5139,10 @@ nfs4_upgrade_open(struct svc_rqst *rqstp, struct nfs4_file *fp, struct svc_fh *c
>>   		set_deny(open->op_share_deny, stp);
>>   		fp->fi_share_deny |=
>>   				(open->op_share_deny & NFS4_SHARE_DENY_BOTH);
>> -	}
>> +	} else if (status == nfserr_share_denied &&
>> +		!nfs4_resolve_deny_conflicts_locked(fp, false, stp,
>> +			open->op_share_deny, false))
>> +		status = nfs_ok;
>>   	spin_unlock(&fp->fi_lock);
>>   
>>   	if (status != nfs_ok)
>> @@ -5399,7 +5482,7 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
>>   			goto out;
>>   		}
>>   	} else {
>> -		status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open);
>> +		status = nfs4_get_vfs_file(rqstp, fp, current_fh, stp, open, true);
>>   		if (status) {
>>   			stp->st_stid.sc_type = NFS4_CLOSED_STID;
>>   			release_open_stateid(stp);
>> -- 
>> 2.9.5