Re: [PATCH RFC v21 2/7] NFSD: add support for share reservation conflict to courteous server

From: dai.ngo@oracle.com
To: Chuck Lever III <chuck.lever@oracle.com>
Cc: Bruce Fields <bfields@fieldses.org>,
	Jeff Layton <jlayton@redhat.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH RFC v21 2/7] NFSD: add support for share reservation conflict to courteous server
Date: Mon, 25 Apr 2022 08:08:53 -0700	[thread overview]
Message-ID: <2cb6bc13-8adc-42fa-29d6-a18b7b20c9ca@oracle.com> (raw)
In-Reply-To: <C0354D9B-B980-405E-B70A-16A8D9761D7F@oracle.com>

On 4/25/22 6:15 AM, Chuck Lever III wrote:
>
>> On Apr 23, 2022, at 2:44 PM, Dai Ngo <dai.ngo@oracle.com> wrote:
>>
>> This patch allows expired client with open state to be in COURTESY
>> state. Share/access conflict with COURTESY client is resolved by
>> setting COURTESY client to EXPIRABLE state, schedule laundromat
>> to run and returning nfserr_jukebox to the request client.
>>
>> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
>> ---
>> fs/nfsd/nfs4state.c | 111 +++++++++++++++++++++++++++++++++++++++++++++++++---
>> 1 file changed, 105 insertions(+), 6 deletions(-)
>>
>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>> index fea5e24e7d94..b08c132648b9 100644
>> --- a/fs/nfsd/nfs4state.c
>> +++ b/fs/nfsd/nfs4state.c
>> @@ -700,6 +700,57 @@ run_laundromat(struct nfsd_net *nn, bool wait)
>> 		flush_workqueue(laundry_wq);
>> }
>>
>> +/*
>> + * Check if courtesy clients have conflicting access and resolve it if possible
>> + *
>> + * 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:
>> + *	false - access/deny mode conflict with normal client.
>> + *	true  - 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;
>> +	bool conflict = true;
>> +	unsigned char bmap;
>> +	struct nfsd_net *nn;
>> +	struct nfs4_client *clp;
>> +
>> +	lockdep_assert_held(&fp->fi_lock);
>> +	list_for_each_entry(st, &fp->fi_stateids, st_perfile) {
>> +		/* ignore lock stateid */
>> +		if (st->st_openstp)
>> +			continue;
>> +		if (st == stp && new_stp)
>> +			continue;
>> +		/* check file access against deny mode or vice versa */
>> +		bmap = share_access ? st->st_deny_bmap : st->st_access_bmap;
>> +		if (!(access & bmap_to_share_mode(bmap)))
>> +			continue;
>> +		clp = st->st_stid.sc_client;
>> +		if (try_to_expire_client(clp))
>> +			continue;
>> +		conflict = false;
>> +		break;
>> +	}
>> +	if (conflict) {
>> +		clp = stp->st_stid.sc_client;
>> +		nn = net_generic(clp->net, nfsd_net_id);
>> +		run_laundromat(nn, false);
>> +	}
>> +	return conflict;
>> +}
>> +
>> static void
>> __nfs4_file_get_access(struct nfs4_file *fp, u32 access)
>> {
>> @@ -4995,13 +5046,14 @@ nfsd4_truncate(struct svc_rqst *rqstp, struct svc_fh *fh,
>>
>> 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;
>> 	int oflag = nfs4_access_to_omode(open->op_share_access);
>> 	int access = nfs4_access_to_access(open->op_share_access);
>> 	unsigned char old_access_bmap, old_deny_bmap;
>> +	struct nfs4_client *clp;
>>
>> 	spin_lock(&fp->fi_lock);
>>
>> @@ -5011,6 +5063,14 @@ 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) {
>> +		if (status != nfserr_share_denied) {
>> +			spin_unlock(&fp->fi_lock);
>> +			goto out;
>> +		}
>> +		clp = stp->st_stid.sc_client;
> @clp is set here, but the value is never used in this function,
> even in later patches. Possibly left over from the previous
> revision of this series?

Thanks Chuck, will fix in v22.
Kernel test robot also reported the problem.

-Dai

>
>
>> +		if (nfs4_resolve_deny_conflicts_locked(fp, new_stp,
>> +				stp, open->op_share_deny, false))
>> +			status = nfserr_jukebox;
>> 		spin_unlock(&fp->fi_lock);
>> 		goto out;
>> 	}
>> @@ -5018,6 +5078,14 @@ static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
>> 	/* set access to the file */
>> 	status = nfs4_file_get_access(fp, open->op_share_access);
>> 	if (status != nfs_ok) {
>> +		if (status != nfserr_share_denied) {
>> +			spin_unlock(&fp->fi_lock);
>> +			goto out;
>> +		}
>> +		clp = stp->st_stid.sc_client;
> Ditto.
>
>
>> +		if (nfs4_resolve_deny_conflicts_locked(fp, new_stp,
>> +				stp, open->op_share_access, true))
>> +			status = nfserr_jukebox;
>> 		spin_unlock(&fp->fi_lock);
>> 		goto out;
>> 	}
>> @@ -5064,21 +5132,29 @@ static __be32 nfs4_get_vfs_file(struct svc_rqst *rqstp, struct nfs4_file *fp,
>> }
>>
>> static __be32
>> -nfs4_upgrade_open(struct svc_rqst *rqstp, struct nfs4_file *fp, struct svc_fh *cur_fh, struct nfs4_ol_stateid *stp, struct nfsd4_open *open)
>> +nfs4_upgrade_open(struct svc_rqst *rqstp, struct nfs4_file *fp,
>> +		struct svc_fh *cur_fh, struct nfs4_ol_stateid *stp,
>> +		struct nfsd4_open *open)
>> {
>> 	__be32 status;
>> 	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);
>> 	status = nfs4_file_check_deny(fp, open->op_share_deny);
>> 	if (status == nfs_ok) {
>> -		set_deny(open->op_share_deny, stp);
>> -		fp->fi_share_deny |=
>> +		if (status != nfserr_share_denied) {
>> +			set_deny(open->op_share_deny, stp);
>> +			fp->fi_share_deny |=
>> 				(open->op_share_deny & NFS4_SHARE_DENY_BOTH);
>> +		} else {
>> +			if (nfs4_resolve_deny_conflicts_locked(fp, false,
>> +					stp, open->op_share_deny, false))
>> +				status = nfserr_jukebox;
>> +		}
>> 	}
>> 	spin_unlock(&fp->fi_lock);
>>
>> @@ -5419,7 +5495,7 @@ 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);
>> @@ -5653,12 +5729,35 @@ static void nfsd4_ssc_expire_umount(struct nfsd_net *nn)
>> }
>> #endif
>>
>> +static bool
>> +nfs4_has_any_locks(struct nfs4_client *clp)
>> +{
>> +	int i;
>> +	struct nfs4_stateowner *so;
>> +
>> +	spin_lock(&clp->cl_lock);
>> +	for (i = 0; i < OWNER_HASH_SIZE; i++) {
>> +		list_for_each_entry(so, &clp->cl_ownerstr_hashtbl[i],
>> +				so_strhash) {
>> +			if (so->so_is_open_owner)
>> +				continue;
>> +			spin_unlock(&clp->cl_lock);
>> +			return true;
>> +		}
>> +	}
>> +	spin_unlock(&clp->cl_lock);
>> +	return false;
>> +}
>> +
>> /*
>>   * place holder for now, no check for lock blockers yet
>>   */
>> static bool
>> nfs4_anylock_blockers(struct nfs4_client *clp)
>> {
>> +	/* not allow locks yet */
>> +	if (nfs4_has_any_locks(clp))
>> +		return true;
>> 	/*
>> 	 * don't want to check for delegation conflict here since
>> 	 * we need the state_lock for it. The laundromat willexpire
>> -- 
>> 2.9.5
>>
> --
> Chuck Lever
>
>
>