Re: [PATCH RFC v23 2/7] NFSD: add support for share reservation conflict to courteous server

[dai.ngo@xxxxxxxxxx]

On 4/29/22 7:36 AM, J. Bruce Fields wrote:
> On Thu, Apr 28, 2022 at 12:06:30AM -0700, Dai Ngo 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@xxxxxxxxxx>
> > ---
> >   fs/nfsd/nfs4state.c | 112 ++++++++++++++++++++++++++++++++++++++++++++++++----
> >   1 file changed, 104 insertions(+), 8 deletions(-)
> >
> > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> > index b84ba19c856b..d2cb820de0ab 100644
> > --- a/fs/nfsd/nfs4state.c
> > +++ b/fs/nfsd/nfs4state.c
> > @@ -694,6 +694,57 @@ static unsigned int file_hashval(struct svc_fh *fh)
> >   
> >   static struct hlist_head file_hashtbl[FILE_HASH_SIZE];
> >   
> > +/*
> > + * 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);
> > +		mod_delayed_work(laundry_wq, &nn->laundromat_work, 0);
> > +	}
> > +	return conflict;
> "conflict" is a confusing name for that variable.  Maybe "resolvable"?

fix in v24.

-Dai

> --b.
>
> > +}
> > +
> >   static void
> >   __nfs4_file_get_access(struct nfs4_file *fp, u32 access)
> >   {
> > @@ -4959,7 +5010,7 @@ 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;
> > @@ -4975,6 +5026,13 @@ 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;
> > +		}
> > +		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;
> >   	}
> > @@ -4982,6 +5040,13 @@ 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;
> > +		}
> > +		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;
> >   	}
> > @@ -5028,21 +5093,29 @@ 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);
> >   
> > @@ -5383,7 +5456,7 @@ 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);
> > @@ -5617,12 +5690,35 @@ 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
> > @@ -5633,8 +5729,8 @@ nfs4_anylock_blockers(struct nfs4_client *clp)
> >   
> >   static bool client_has_state_tmp(struct nfs4_client *clp)
> >   {
> > -	if (!list_empty(&clp->cl_delegations) &&
> > -			!client_has_openowners(clp) &&
> > +	if (((!list_empty(&clp->cl_delegations)) ||
> > +			client_has_openowners(clp)) &&
> >   			list_empty(&clp->async_copies))
> >   		return true;
> >   	return false;
> > --
> > 2.9.5