diff mbox series

[RFC,v23,1/7] NFSD: add courteous server support for thread with only delegation

Message ID 1651129595-6904-2-git-send-email-dai.ngo@oracle.com (mailing list archive)
State New
Headers show
Series NFSD: Initial implementation of NFSv4 Courteous Server | expand

Commit Message

Dai Ngo April 28, 2022, 7:06 a.m. UTC
This patch provides courteous server support for delegation only.
Only expired client with delegation but no conflict and no open
or lock state is allowed to be in COURTESY state.

Delegation conflict with COURTESY/EXPIRABLE client is resolved by
setting it to EXPIRABLE, queue work for the laundromat and return
delay to the caller. Conflict is resolved when the laudromat runs
and expires the EXIRABLE client while the NFS client retries the
OPEN request. Local thread request that gets conflict is doing the
retry in _break_lease.

Client in COURTESY or EXPIRABLE state is allowed to reconnect and
continues to have access to its state. Access to the nfs4_client by
the reconnecting thread and the laundromat is serialized via the
client_lock.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/nfsd/nfs4state.c | 79 ++++++++++++++++++++++++++++++++++++++++++++---------
 fs/nfsd/nfsd.h      |  1 +
 fs/nfsd/state.h     | 29 ++++++++++++++++++++
 3 files changed, 96 insertions(+), 13 deletions(-)

Comments

J.Bruce Fields April 29, 2022, 2:16 p.m. UTC | #1
On Thu, Apr 28, 2022 at 12:06:29AM -0700, Dai Ngo wrote:
> This patch provides courteous server support for delegation only.
> Only expired client with delegation but no conflict and no open
> or lock state is allowed to be in COURTESY state.
> 
> Delegation conflict with COURTESY/EXPIRABLE client is resolved by
> setting it to EXPIRABLE, queue work for the laundromat and return
> delay to the caller. Conflict is resolved when the laudromat runs
> and expires the EXIRABLE client while the NFS client retries the
> OPEN request. Local thread request that gets conflict is doing the
> retry in _break_lease.
> 
> Client in COURTESY or EXPIRABLE state is allowed to reconnect and
> continues to have access to its state. Access to the nfs4_client by
> the reconnecting thread and the laundromat is serialized via the
> client_lock.
> 
> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> ---
>  fs/nfsd/nfs4state.c | 79 ++++++++++++++++++++++++++++++++++++++++++++---------
>  fs/nfsd/nfsd.h      |  1 +
>  fs/nfsd/state.h     | 29 ++++++++++++++++++++
>  3 files changed, 96 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 234e852fcdfa..b84ba19c856b 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -125,6 +125,8 @@ static void free_session(struct nfsd4_session *);
>  static const struct nfsd4_callback_ops nfsd4_cb_recall_ops;
>  static const struct nfsd4_callback_ops nfsd4_cb_notify_lock_ops;
>  
> +static struct workqueue_struct *laundry_wq;
> +
>  static bool is_session_dead(struct nfsd4_session *ses)
>  {
>  	return ses->se_flags & NFS4_SESSION_DEAD;
> @@ -152,6 +154,7 @@ static __be32 get_client_locked(struct nfs4_client *clp)
>  	if (is_client_expired(clp))
>  		return nfserr_expired;
>  	atomic_inc(&clp->cl_rpc_users);
> +	clp->cl_state = NFSD4_ACTIVE;
>  	return nfs_ok;
>  }
>  
> @@ -172,6 +175,7 @@ renew_client_locked(struct nfs4_client *clp)
>  
>  	list_move_tail(&clp->cl_lru, &nn->client_lru);
>  	clp->cl_time = ktime_get_boottime_seconds();
> +	clp->cl_state = NFSD4_ACTIVE;
>  }
>  
>  static void put_client_renew_locked(struct nfs4_client *clp)
> @@ -2004,6 +2008,7 @@ static struct nfs4_client *alloc_client(struct xdr_netobj name)
>  	idr_init(&clp->cl_stateids);
>  	atomic_set(&clp->cl_rpc_users, 0);
>  	clp->cl_cb_state = NFSD4_CB_UNKNOWN;
> +	clp->cl_state = NFSD4_ACTIVE;
>  	INIT_LIST_HEAD(&clp->cl_idhash);
>  	INIT_LIST_HEAD(&clp->cl_openowners);
>  	INIT_LIST_HEAD(&clp->cl_delegations);
> @@ -4694,9 +4699,16 @@ nfsd_break_deleg_cb(struct file_lock *fl)
>  	bool ret = false;
>  	struct nfs4_delegation *dp = (struct nfs4_delegation *)fl->fl_owner;
>  	struct nfs4_file *fp = dp->dl_stid.sc_file;
> +	struct nfs4_client *clp = dp->dl_stid.sc_client;
> +	struct nfsd_net *nn;
>  
>  	trace_nfsd_cb_recall(&dp->dl_stid);
>  
> +	if (try_to_expire_client(clp)) {
> +		nn = net_generic(clp->net, nfsd_net_id);
> +		mod_delayed_work(laundry_wq, &nn->laundromat_work, 0);
> +	}
> +
>  	/*
>  	 * We don't want the locks code to timeout the lease for us;
>  	 * we'll remove it ourself if a delegation isn't returned
> @@ -5605,6 +5617,58 @@ static void nfsd4_ssc_expire_umount(struct nfsd_net *nn)
>  }
>  #endif
>  
> +/*
> + * place holder for now, no check for lock blockers yet
> + */
> +static bool
> +nfs4_anylock_blockers(struct nfs4_client *clp)
> +{
> +	/*
> +	 * don't want to check for delegation conflict here since
> +	 * we need the state_lock for it. The laundromat willexpire
> +	 * COURTESY later when checking for delegation recall timeout.
> +	 */
> +	return false;
> +}
> +
> +static bool client_has_state_tmp(struct nfs4_client *clp)
> +{
> +	if (!list_empty(&clp->cl_delegations) &&
> +			!client_has_openowners(clp) &&
> +			list_empty(&clp->async_copies))
> +		return true;
> +	return false;
> +}
> +
> +static void
> +nfs4_get_client_reaplist(struct nfsd_net *nn, struct list_head *reaplist,
> +				struct laundry_time *lt)
> +{
> +	struct list_head *pos, *next;
> +	struct nfs4_client *clp;
> +
> +	INIT_LIST_HEAD(reaplist);
> +	spin_lock(&nn->client_lock);
> +	list_for_each_safe(pos, next, &nn->client_lru) {
> +		clp = list_entry(pos, struct nfs4_client, cl_lru);
> +		if (clp->cl_state == NFSD4_EXPIRABLE)
> +			goto exp_client;
> +		if (!state_expired(lt, clp->cl_time))
> +			break;
> +		clp->cl_state = NFSD4_COURTESY;
> +		if (!client_has_state_tmp(clp) ||
> +				ktime_get_boottime_seconds() >=
> +				(clp->cl_time + NFSD_COURTESY_CLIENT_TIMEOUT))
> +			goto exp_client;
> +		if (nfs4_anylock_blockers(clp)) {
> +exp_client:
> +			if (!mark_client_expired_locked(clp))
> +				list_add(&clp->cl_lru, reaplist);
> +		}
> +	}
> +	spin_unlock(&nn->client_lock);
> +}
> +
>  static time64_t
>  nfs4_laundromat(struct nfsd_net *nn)
>  {
> @@ -5627,7 +5691,6 @@ nfs4_laundromat(struct nfsd_net *nn)
>  		goto out;
>  	}
>  	nfsd4_end_grace(nn);
> -	INIT_LIST_HEAD(&reaplist);
>  
>  	spin_lock(&nn->s2s_cp_lock);
>  	idr_for_each_entry(&nn->s2s_cp_stateids, cps_t, i) {
> @@ -5637,17 +5700,7 @@ nfs4_laundromat(struct nfsd_net *nn)
>  			_free_cpntf_state_locked(nn, cps);
>  	}
>  	spin_unlock(&nn->s2s_cp_lock);
> -
> -	spin_lock(&nn->client_lock);
> -	list_for_each_safe(pos, next, &nn->client_lru) {
> -		clp = list_entry(pos, struct nfs4_client, cl_lru);
> -		if (!state_expired(&lt, clp->cl_time))
> -			break;
> -		if (mark_client_expired_locked(clp))
> -			continue;
> -		list_add(&clp->cl_lru, &reaplist);
> -	}
> -	spin_unlock(&nn->client_lock);
> +	nfs4_get_client_reaplist(nn, &reaplist, &lt);
>  	list_for_each_safe(pos, next, &reaplist) {
>  		clp = list_entry(pos, struct nfs4_client, cl_lru);
>  		trace_nfsd_clid_purged(&clp->cl_clientid);
> @@ -5657,6 +5710,7 @@ nfs4_laundromat(struct nfsd_net *nn)
>  	spin_lock(&state_lock);
>  	list_for_each_safe(pos, next, &nn->del_recall_lru) {
>  		dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
> +		try_to_expire_client(dp->dl_stid.sc_client);

I don't think this quite works.  First, we're only looping over the
delegations that have been under recall for the longest, and those
aren't the only ones that may matter.  Second, just calling
try_to_expire_client isn't enough, we also need to reschedule the
laundromat.

It's not the end of the world, we'll just have to wait another lease
period, but I think we can do better.

How about something like the below?  (Incomplete.)   And then you can
check cl_delegs_in_recall in nfs4_anylock_blockers.

Otherwise, this patch seems OK to me.

--b.

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 4f45caead507..23041584d84f 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4780,6 +4780,9 @@ nfsd_break_deleg_cb(struct file_lock *fl)
 
 	trace_nfsd_cb_recall(&dp->dl_stid);
 
+	dp->dl_recalled = true;
+	atomic_inc(&clp->cl_delegs_in_recall);
+
 	if (!try_to_expire_client(clp)) {
 		nn = net_generic(clp->net, nfsd_net_id);
 		mod_delayed_work(laundry_wq, &nn->laundromat_work, 0);
@@ -4827,9 +4830,14 @@ static int
 nfsd_change_deleg_cb(struct file_lock *onlist, int arg,
 		     struct list_head *dispose)
 {
-	if (arg & F_UNLCK)
+	struct nfs4_delegation *dp = (struct nfs4_delegation *)onlist->fl_owner;
+	struct nfs4_client *clp = dp->dl_stid.sc_client;
+
+	if (arg & F_UNLCK) {
+		if (dp->dl_recalled)
+			atomic_dec(&clp->cl_delegs_in_recall);
 		return lease_modify(onlist, arg, dispose);
-	else
+	} else
 		return -EAGAIN;
 }
J.Bruce Fields April 29, 2022, 2:55 p.m. UTC | #2
On Thu, Apr 28, 2022 at 12:06:29AM -0700, Dai Ngo wrote:
> This patch provides courteous server support for delegation only.
> Only expired client with delegation but no conflict and no open
> or lock state is allowed to be in COURTESY state.
> 
> Delegation conflict with COURTESY/EXPIRABLE client is resolved by
> setting it to EXPIRABLE, queue work for the laundromat and return
> delay to the caller. Conflict is resolved when the laudromat runs
> and expires the EXIRABLE client while the NFS client retries the
> OPEN request. Local thread request that gets conflict is doing the
> retry in _break_lease.
> 
> Client in COURTESY or EXPIRABLE state is allowed to reconnect and
> continues to have access to its state. Access to the nfs4_client by
> the reconnecting thread and the laundromat is serialized via the
> client_lock.
> 
> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> ---
>  fs/nfsd/nfs4state.c | 79 ++++++++++++++++++++++++++++++++++++++++++++---------
>  fs/nfsd/nfsd.h      |  1 +
>  fs/nfsd/state.h     | 29 ++++++++++++++++++++
>  3 files changed, 96 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 234e852fcdfa..b84ba19c856b 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -125,6 +125,8 @@ static void free_session(struct nfsd4_session *);
>  static const struct nfsd4_callback_ops nfsd4_cb_recall_ops;
>  static const struct nfsd4_callback_ops nfsd4_cb_notify_lock_ops;
>  
> +static struct workqueue_struct *laundry_wq;
> +
>  static bool is_session_dead(struct nfsd4_session *ses)
>  {
>  	return ses->se_flags & NFS4_SESSION_DEAD;
> @@ -152,6 +154,7 @@ static __be32 get_client_locked(struct nfs4_client *clp)
>  	if (is_client_expired(clp))
>  		return nfserr_expired;
>  	atomic_inc(&clp->cl_rpc_users);
> +	clp->cl_state = NFSD4_ACTIVE;
>  	return nfs_ok;
>  }
>  
> @@ -172,6 +175,7 @@ renew_client_locked(struct nfs4_client *clp)
>  
>  	list_move_tail(&clp->cl_lru, &nn->client_lru);
>  	clp->cl_time = ktime_get_boottime_seconds();
> +	clp->cl_state = NFSD4_ACTIVE;
>  }
>  
>  static void put_client_renew_locked(struct nfs4_client *clp)
> @@ -2004,6 +2008,7 @@ static struct nfs4_client *alloc_client(struct xdr_netobj name)
>  	idr_init(&clp->cl_stateids);
>  	atomic_set(&clp->cl_rpc_users, 0);
>  	clp->cl_cb_state = NFSD4_CB_UNKNOWN;
> +	clp->cl_state = NFSD4_ACTIVE;
>  	INIT_LIST_HEAD(&clp->cl_idhash);
>  	INIT_LIST_HEAD(&clp->cl_openowners);
>  	INIT_LIST_HEAD(&clp->cl_delegations);
> @@ -4694,9 +4699,16 @@ nfsd_break_deleg_cb(struct file_lock *fl)
>  	bool ret = false;
>  	struct nfs4_delegation *dp = (struct nfs4_delegation *)fl->fl_owner;
>  	struct nfs4_file *fp = dp->dl_stid.sc_file;
> +	struct nfs4_client *clp = dp->dl_stid.sc_client;
> +	struct nfsd_net *nn;
>  
>  	trace_nfsd_cb_recall(&dp->dl_stid);
>  
> +	if (try_to_expire_client(clp)) {
> +		nn = net_generic(clp->net, nfsd_net_id);
> +		mod_delayed_work(laundry_wq, &nn->laundromat_work, 0);
> +	}
> +
>  	/*
>  	 * We don't want the locks code to timeout the lease for us;
>  	 * we'll remove it ourself if a delegation isn't returned
> @@ -5605,6 +5617,58 @@ static void nfsd4_ssc_expire_umount(struct nfsd_net *nn)
>  }
>  #endif
>  
> +/*
> + * place holder for now, no check for lock blockers yet
> + */
> +static bool
> +nfs4_anylock_blockers(struct nfs4_client *clp)
> +{
> +	/*
> +	 * don't want to check for delegation conflict here since
> +	 * we need the state_lock for it. The laundromat willexpire
> +	 * COURTESY later when checking for delegation recall timeout.
> +	 */
> +	return false;
> +}
> +
> +static bool client_has_state_tmp(struct nfs4_client *clp)

Why the "_tmp"?

> +{
> +	if (!list_empty(&clp->cl_delegations) &&
> +			!client_has_openowners(clp) &&
> +			list_empty(&clp->async_copies))

I would have expected

	if (!list_empty(&clp->cl_delegations) ||
		client_has_openowners(clp) ||
		!list_empty(&clp->async_copies))

?--b.

> +		return true;
> +	return false;
> +}
> +
> +static void
> +nfs4_get_client_reaplist(struct nfsd_net *nn, struct list_head *reaplist,
> +				struct laundry_time *lt)
> +{
> +	struct list_head *pos, *next;
> +	struct nfs4_client *clp;
> +
> +	INIT_LIST_HEAD(reaplist);
> +	spin_lock(&nn->client_lock);
> +	list_for_each_safe(pos, next, &nn->client_lru) {
> +		clp = list_entry(pos, struct nfs4_client, cl_lru);
> +		if (clp->cl_state == NFSD4_EXPIRABLE)
> +			goto exp_client;
> +		if (!state_expired(lt, clp->cl_time))
> +			break;
> +		clp->cl_state = NFSD4_COURTESY;
> +		if (!client_has_state_tmp(clp) ||
> +				ktime_get_boottime_seconds() >=
> +				(clp->cl_time + NFSD_COURTESY_CLIENT_TIMEOUT))
> +			goto exp_client;
> +		if (nfs4_anylock_blockers(clp)) {
> +exp_client:
> +			if (!mark_client_expired_locked(clp))
> +				list_add(&clp->cl_lru, reaplist);
> +		}
> +	}
> +	spin_unlock(&nn->client_lock);
> +}
> +
>  static time64_t
>  nfs4_laundromat(struct nfsd_net *nn)
>  {
> @@ -5627,7 +5691,6 @@ nfs4_laundromat(struct nfsd_net *nn)
>  		goto out;
>  	}
>  	nfsd4_end_grace(nn);
> -	INIT_LIST_HEAD(&reaplist);
>  
>  	spin_lock(&nn->s2s_cp_lock);
>  	idr_for_each_entry(&nn->s2s_cp_stateids, cps_t, i) {
> @@ -5637,17 +5700,7 @@ nfs4_laundromat(struct nfsd_net *nn)
>  			_free_cpntf_state_locked(nn, cps);
>  	}
>  	spin_unlock(&nn->s2s_cp_lock);
> -
> -	spin_lock(&nn->client_lock);
> -	list_for_each_safe(pos, next, &nn->client_lru) {
> -		clp = list_entry(pos, struct nfs4_client, cl_lru);
> -		if (!state_expired(&lt, clp->cl_time))
> -			break;
> -		if (mark_client_expired_locked(clp))
> -			continue;
> -		list_add(&clp->cl_lru, &reaplist);
> -	}
> -	spin_unlock(&nn->client_lock);
> +	nfs4_get_client_reaplist(nn, &reaplist, &lt);
>  	list_for_each_safe(pos, next, &reaplist) {
>  		clp = list_entry(pos, struct nfs4_client, cl_lru);
>  		trace_nfsd_clid_purged(&clp->cl_clientid);
> @@ -5657,6 +5710,7 @@ nfs4_laundromat(struct nfsd_net *nn)
>  	spin_lock(&state_lock);
>  	list_for_each_safe(pos, next, &nn->del_recall_lru) {
>  		dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
> +		try_to_expire_client(dp->dl_stid.sc_client);
>  		if (!state_expired(&lt, dp->dl_time))
>  			break;
>  		WARN_ON(!unhash_delegation_locked(dp));
> @@ -5722,7 +5776,6 @@ nfs4_laundromat(struct nfsd_net *nn)
>  	return max_t(time64_t, lt.new_timeo, NFSD_LAUNDROMAT_MINTIMEOUT);
>  }
>  
> -static struct workqueue_struct *laundry_wq;
>  static void laundromat_main(struct work_struct *);
>  
>  static void
> diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
> index 4fc1fd639527..23996c6ca75e 100644
> --- a/fs/nfsd/nfsd.h
> +++ b/fs/nfsd/nfsd.h
> @@ -336,6 +336,7 @@ void		nfsd_lockd_shutdown(void);
>  #define COMPOUND_ERR_SLACK_SPACE	16     /* OP_SETATTR */
>  
>  #define NFSD_LAUNDROMAT_MINTIMEOUT      1   /* seconds */
> +#define	NFSD_COURTESY_CLIENT_TIMEOUT	(24 * 60 * 60)	/* seconds */
>  
>  /*
>   * The following attributes are currently not supported by the NFSv4 server:
> diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
> index 95457cfd37fc..bd15f2863823 100644
> --- a/fs/nfsd/state.h
> +++ b/fs/nfsd/state.h
> @@ -283,6 +283,28 @@ struct nfsd4_sessionid {
>  #define HEXDIR_LEN     33 /* hex version of 16 byte md5 of cl_name plus '\0' */
>  
>  /*
> + *       State                Meaning                  Where set
> + * --------------------------------------------------------------------------
> + * | NFSD4_ACTIVE      | Confirmed, active    | Default                     |
> + * |------------------- ----------------------------------------------------|
> + * | NFSD4_COURTESY    | Courtesy state.      | nfs4_get_client_reaplist    |
> + * |                   | Lease/lock/share     |                             |
> + * |                   | reservation conflict |                             |
> + * |                   | can cause Courtesy   |                             |
> + * |                   | client to be expired |                             |
> + * |------------------------------------------------------------------------|
> + * | NFSD4_EXPIRABLE   | Courtesy client to be| nfs4_laundromat             |
> + * |                   | expired by Laundromat| try_to_expire_client        |
> + * |                   | due to conflict      |                             |
> + * |------------------------------------------------------------------------|
> + */
> +enum {
> +	NFSD4_ACTIVE = 0,
> +	NFSD4_COURTESY,
> +	NFSD4_EXPIRABLE,
> +};
> +
> +/*
>   * struct nfs4_client - one per client.  Clientids live here.
>   *
>   * The initial object created by an NFS client using SETCLIENTID (for NFSv4.0)
> @@ -385,6 +407,8 @@ struct nfs4_client {
>  	struct list_head	async_copies;	/* list of async copies */
>  	spinlock_t		async_lock;	/* lock for async copies */
>  	atomic_t		cl_cb_inflight;	/* Outstanding callbacks */
> +
> +	unsigned int		cl_state;
>  };
>  
>  /* struct nfs4_client_reset
> @@ -702,4 +726,9 @@ extern void nfsd4_client_record_remove(struct nfs4_client *clp);
>  extern int nfsd4_client_record_check(struct nfs4_client *clp);
>  extern void nfsd4_record_grace_done(struct nfsd_net *nn);
>  
> +static inline bool try_to_expire_client(struct nfs4_client *clp)
> +{
> +	cmpxchg(&clp->cl_state, NFSD4_COURTESY, NFSD4_EXPIRABLE);
> +	return clp->cl_state == NFSD4_EXPIRABLE;
> +}
>  #endif   /* NFSD4_STATE_H */
> -- 
> 2.9.5
Dai Ngo April 29, 2022, 5:21 p.m. UTC | #3
On 4/29/22 7:55 AM, J. Bruce Fields wrote:
> On Thu, Apr 28, 2022 at 12:06:29AM -0700, Dai Ngo wrote:
>> This patch provides courteous server support for delegation only.
>> Only expired client with delegation but no conflict and no open
>> or lock state is allowed to be in COURTESY state.
>>
>> Delegation conflict with COURTESY/EXPIRABLE client is resolved by
>> setting it to EXPIRABLE, queue work for the laundromat and return
>> delay to the caller. Conflict is resolved when the laudromat runs
>> and expires the EXIRABLE client while the NFS client retries the
>> OPEN request. Local thread request that gets conflict is doing the
>> retry in _break_lease.
>>
>> Client in COURTESY or EXPIRABLE state is allowed to reconnect and
>> continues to have access to its state. Access to the nfs4_client by
>> the reconnecting thread and the laundromat is serialized via the
>> client_lock.
>>
>> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
>> ---
>>   fs/nfsd/nfs4state.c | 79 ++++++++++++++++++++++++++++++++++++++++++++---------
>>   fs/nfsd/nfsd.h      |  1 +
>>   fs/nfsd/state.h     | 29 ++++++++++++++++++++
>>   3 files changed, 96 insertions(+), 13 deletions(-)
>>
>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>> index 234e852fcdfa..b84ba19c856b 100644
>> --- a/fs/nfsd/nfs4state.c
>> +++ b/fs/nfsd/nfs4state.c
>> @@ -125,6 +125,8 @@ static void free_session(struct nfsd4_session *);
>>   static const struct nfsd4_callback_ops nfsd4_cb_recall_ops;
>>   static const struct nfsd4_callback_ops nfsd4_cb_notify_lock_ops;
>>   
>> +static struct workqueue_struct *laundry_wq;
>> +
>>   static bool is_session_dead(struct nfsd4_session *ses)
>>   {
>>   	return ses->se_flags & NFS4_SESSION_DEAD;
>> @@ -152,6 +154,7 @@ static __be32 get_client_locked(struct nfs4_client *clp)
>>   	if (is_client_expired(clp))
>>   		return nfserr_expired;
>>   	atomic_inc(&clp->cl_rpc_users);
>> +	clp->cl_state = NFSD4_ACTIVE;
>>   	return nfs_ok;
>>   }
>>   
>> @@ -172,6 +175,7 @@ renew_client_locked(struct nfs4_client *clp)
>>   
>>   	list_move_tail(&clp->cl_lru, &nn->client_lru);
>>   	clp->cl_time = ktime_get_boottime_seconds();
>> +	clp->cl_state = NFSD4_ACTIVE;
>>   }
>>   
>>   static void put_client_renew_locked(struct nfs4_client *clp)
>> @@ -2004,6 +2008,7 @@ static struct nfs4_client *alloc_client(struct xdr_netobj name)
>>   	idr_init(&clp->cl_stateids);
>>   	atomic_set(&clp->cl_rpc_users, 0);
>>   	clp->cl_cb_state = NFSD4_CB_UNKNOWN;
>> +	clp->cl_state = NFSD4_ACTIVE;
>>   	INIT_LIST_HEAD(&clp->cl_idhash);
>>   	INIT_LIST_HEAD(&clp->cl_openowners);
>>   	INIT_LIST_HEAD(&clp->cl_delegations);
>> @@ -4694,9 +4699,16 @@ nfsd_break_deleg_cb(struct file_lock *fl)
>>   	bool ret = false;
>>   	struct nfs4_delegation *dp = (struct nfs4_delegation *)fl->fl_owner;
>>   	struct nfs4_file *fp = dp->dl_stid.sc_file;
>> +	struct nfs4_client *clp = dp->dl_stid.sc_client;
>> +	struct nfsd_net *nn;
>>   
>>   	trace_nfsd_cb_recall(&dp->dl_stid);
>>   
>> +	if (try_to_expire_client(clp)) {
>> +		nn = net_generic(clp->net, nfsd_net_id);
>> +		mod_delayed_work(laundry_wq, &nn->laundromat_work, 0);
>> +	}
>> +
>>   	/*
>>   	 * We don't want the locks code to timeout the lease for us;
>>   	 * we'll remove it ourself if a delegation isn't returned
>> @@ -5605,6 +5617,58 @@ static void nfsd4_ssc_expire_umount(struct nfsd_net *nn)
>>   }
>>   #endif
>>   
>> +/*
>> + * place holder for now, no check for lock blockers yet
>> + */
>> +static bool
>> +nfs4_anylock_blockers(struct nfs4_client *clp)
>> +{
>> +	/*
>> +	 * don't want to check for delegation conflict here since
>> +	 * we need the state_lock for it. The laundromat willexpire
>> +	 * COURTESY later when checking for delegation recall timeout.
>> +	 */
>> +	return false;
>> +}
>> +
>> +static bool client_has_state_tmp(struct nfs4_client *clp)
> Why the "_tmp"?
>
>> +{
>> +	if (!list_empty(&clp->cl_delegations) &&
>> +			!client_has_openowners(clp) &&
>> +			list_empty(&clp->async_copies))
> I would have expected
>
> 	if (!list_empty(&clp->cl_delegations) ||
> 		client_has_openowners(clp) ||
> 		!list_empty(&clp->async_copies))

In patch 1, we want to allow *only* clients with non-conflict delegation
to be in COURTESY state, not with opens and locks. So for that, we can not
use the existing client_has_state (until patch 6), so I just created
client_has_state_tmp for it.

-Dai

>
> ?--b.
>
>> +		return true;
>> +	return false;
>> +}
>> +
>> +static void
>> +nfs4_get_client_reaplist(struct nfsd_net *nn, struct list_head *reaplist,
>> +				struct laundry_time *lt)
>> +{
>> +	struct list_head *pos, *next;
>> +	struct nfs4_client *clp;
>> +
>> +	INIT_LIST_HEAD(reaplist);
>> +	spin_lock(&nn->client_lock);
>> +	list_for_each_safe(pos, next, &nn->client_lru) {
>> +		clp = list_entry(pos, struct nfs4_client, cl_lru);
>> +		if (clp->cl_state == NFSD4_EXPIRABLE)
>> +			goto exp_client;
>> +		if (!state_expired(lt, clp->cl_time))
>> +			break;
>> +		clp->cl_state = NFSD4_COURTESY;
>> +		if (!client_has_state_tmp(clp) ||
>> +				ktime_get_boottime_seconds() >=
>> +				(clp->cl_time + NFSD_COURTESY_CLIENT_TIMEOUT))
>> +			goto exp_client;
>> +		if (nfs4_anylock_blockers(clp)) {
>> +exp_client:
>> +			if (!mark_client_expired_locked(clp))
>> +				list_add(&clp->cl_lru, reaplist);
>> +		}
>> +	}
>> +	spin_unlock(&nn->client_lock);
>> +}
>> +
>>   static time64_t
>>   nfs4_laundromat(struct nfsd_net *nn)
>>   {
>> @@ -5627,7 +5691,6 @@ nfs4_laundromat(struct nfsd_net *nn)
>>   		goto out;
>>   	}
>>   	nfsd4_end_grace(nn);
>> -	INIT_LIST_HEAD(&reaplist);
>>   
>>   	spin_lock(&nn->s2s_cp_lock);
>>   	idr_for_each_entry(&nn->s2s_cp_stateids, cps_t, i) {
>> @@ -5637,17 +5700,7 @@ nfs4_laundromat(struct nfsd_net *nn)
>>   			_free_cpntf_state_locked(nn, cps);
>>   	}
>>   	spin_unlock(&nn->s2s_cp_lock);
>> -
>> -	spin_lock(&nn->client_lock);
>> -	list_for_each_safe(pos, next, &nn->client_lru) {
>> -		clp = list_entry(pos, struct nfs4_client, cl_lru);
>> -		if (!state_expired(&lt, clp->cl_time))
>> -			break;
>> -		if (mark_client_expired_locked(clp))
>> -			continue;
>> -		list_add(&clp->cl_lru, &reaplist);
>> -	}
>> -	spin_unlock(&nn->client_lock);
>> +	nfs4_get_client_reaplist(nn, &reaplist, &lt);
>>   	list_for_each_safe(pos, next, &reaplist) {
>>   		clp = list_entry(pos, struct nfs4_client, cl_lru);
>>   		trace_nfsd_clid_purged(&clp->cl_clientid);
>> @@ -5657,6 +5710,7 @@ nfs4_laundromat(struct nfsd_net *nn)
>>   	spin_lock(&state_lock);
>>   	list_for_each_safe(pos, next, &nn->del_recall_lru) {
>>   		dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
>> +		try_to_expire_client(dp->dl_stid.sc_client);
>>   		if (!state_expired(&lt, dp->dl_time))
>>   			break;
>>   		WARN_ON(!unhash_delegation_locked(dp));
>> @@ -5722,7 +5776,6 @@ nfs4_laundromat(struct nfsd_net *nn)
>>   	return max_t(time64_t, lt.new_timeo, NFSD_LAUNDROMAT_MINTIMEOUT);
>>   }
>>   
>> -static struct workqueue_struct *laundry_wq;
>>   static void laundromat_main(struct work_struct *);
>>   
>>   static void
>> diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
>> index 4fc1fd639527..23996c6ca75e 100644
>> --- a/fs/nfsd/nfsd.h
>> +++ b/fs/nfsd/nfsd.h
>> @@ -336,6 +336,7 @@ void		nfsd_lockd_shutdown(void);
>>   #define COMPOUND_ERR_SLACK_SPACE	16     /* OP_SETATTR */
>>   
>>   #define NFSD_LAUNDROMAT_MINTIMEOUT      1   /* seconds */
>> +#define	NFSD_COURTESY_CLIENT_TIMEOUT	(24 * 60 * 60)	/* seconds */
>>   
>>   /*
>>    * The following attributes are currently not supported by the NFSv4 server:
>> diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
>> index 95457cfd37fc..bd15f2863823 100644
>> --- a/fs/nfsd/state.h
>> +++ b/fs/nfsd/state.h
>> @@ -283,6 +283,28 @@ struct nfsd4_sessionid {
>>   #define HEXDIR_LEN     33 /* hex version of 16 byte md5 of cl_name plus '\0' */
>>   
>>   /*
>> + *       State                Meaning                  Where set
>> + * --------------------------------------------------------------------------
>> + * | NFSD4_ACTIVE      | Confirmed, active    | Default                     |
>> + * |------------------- ----------------------------------------------------|
>> + * | NFSD4_COURTESY    | Courtesy state.      | nfs4_get_client_reaplist    |
>> + * |                   | Lease/lock/share     |                             |
>> + * |                   | reservation conflict |                             |
>> + * |                   | can cause Courtesy   |                             |
>> + * |                   | client to be expired |                             |
>> + * |------------------------------------------------------------------------|
>> + * | NFSD4_EXPIRABLE   | Courtesy client to be| nfs4_laundromat             |
>> + * |                   | expired by Laundromat| try_to_expire_client        |
>> + * |                   | due to conflict      |                             |
>> + * |------------------------------------------------------------------------|
>> + */
>> +enum {
>> +	NFSD4_ACTIVE = 0,
>> +	NFSD4_COURTESY,
>> +	NFSD4_EXPIRABLE,
>> +};
>> +
>> +/*
>>    * struct nfs4_client - one per client.  Clientids live here.
>>    *
>>    * The initial object created by an NFS client using SETCLIENTID (for NFSv4.0)
>> @@ -385,6 +407,8 @@ struct nfs4_client {
>>   	struct list_head	async_copies;	/* list of async copies */
>>   	spinlock_t		async_lock;	/* lock for async copies */
>>   	atomic_t		cl_cb_inflight;	/* Outstanding callbacks */
>> +
>> +	unsigned int		cl_state;
>>   };
>>   
>>   /* struct nfs4_client_reset
>> @@ -702,4 +726,9 @@ extern void nfsd4_client_record_remove(struct nfs4_client *clp);
>>   extern int nfsd4_client_record_check(struct nfs4_client *clp);
>>   extern void nfsd4_record_grace_done(struct nfsd_net *nn);
>>   
>> +static inline bool try_to_expire_client(struct nfs4_client *clp)
>> +{
>> +	cmpxchg(&clp->cl_state, NFSD4_COURTESY, NFSD4_EXPIRABLE);
>> +	return clp->cl_state == NFSD4_EXPIRABLE;
>> +}
>>   #endif   /* NFSD4_STATE_H */
>> -- 
>> 2.9.5
Dai Ngo April 29, 2022, 5:26 p.m. UTC | #4
On 4/29/22 7:16 AM, J. Bruce Fields wrote:
> On Thu, Apr 28, 2022 at 12:06:29AM -0700, Dai Ngo wrote:
>> This patch provides courteous server support for delegation only.
>> Only expired client with delegation but no conflict and no open
>> or lock state is allowed to be in COURTESY state.
>>
>> Delegation conflict with COURTESY/EXPIRABLE client is resolved by
>> setting it to EXPIRABLE, queue work for the laundromat and return
>> delay to the caller. Conflict is resolved when the laudromat runs
>> and expires the EXIRABLE client while the NFS client retries the
>> OPEN request. Local thread request that gets conflict is doing the
>> retry in _break_lease.
>>
>> Client in COURTESY or EXPIRABLE state is allowed to reconnect and
>> continues to have access to its state. Access to the nfs4_client by
>> the reconnecting thread and the laundromat is serialized via the
>> client_lock.
>>
>> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
>> ---
>>   fs/nfsd/nfs4state.c | 79 ++++++++++++++++++++++++++++++++++++++++++++---------
>>   fs/nfsd/nfsd.h      |  1 +
>>   fs/nfsd/state.h     | 29 ++++++++++++++++++++
>>   3 files changed, 96 insertions(+), 13 deletions(-)
>>
>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>> index 234e852fcdfa..b84ba19c856b 100644
>> --- a/fs/nfsd/nfs4state.c
>> +++ b/fs/nfsd/nfs4state.c
>> @@ -125,6 +125,8 @@ static void free_session(struct nfsd4_session *);
>>   static const struct nfsd4_callback_ops nfsd4_cb_recall_ops;
>>   static const struct nfsd4_callback_ops nfsd4_cb_notify_lock_ops;
>>   
>> +static struct workqueue_struct *laundry_wq;
>> +
>>   static bool is_session_dead(struct nfsd4_session *ses)
>>   {
>>   	return ses->se_flags & NFS4_SESSION_DEAD;
>> @@ -152,6 +154,7 @@ static __be32 get_client_locked(struct nfs4_client *clp)
>>   	if (is_client_expired(clp))
>>   		return nfserr_expired;
>>   	atomic_inc(&clp->cl_rpc_users);
>> +	clp->cl_state = NFSD4_ACTIVE;
>>   	return nfs_ok;
>>   }
>>   
>> @@ -172,6 +175,7 @@ renew_client_locked(struct nfs4_client *clp)
>>   
>>   	list_move_tail(&clp->cl_lru, &nn->client_lru);
>>   	clp->cl_time = ktime_get_boottime_seconds();
>> +	clp->cl_state = NFSD4_ACTIVE;
>>   }
>>   
>>   static void put_client_renew_locked(struct nfs4_client *clp)
>> @@ -2004,6 +2008,7 @@ static struct nfs4_client *alloc_client(struct xdr_netobj name)
>>   	idr_init(&clp->cl_stateids);
>>   	atomic_set(&clp->cl_rpc_users, 0);
>>   	clp->cl_cb_state = NFSD4_CB_UNKNOWN;
>> +	clp->cl_state = NFSD4_ACTIVE;
>>   	INIT_LIST_HEAD(&clp->cl_idhash);
>>   	INIT_LIST_HEAD(&clp->cl_openowners);
>>   	INIT_LIST_HEAD(&clp->cl_delegations);
>> @@ -4694,9 +4699,16 @@ nfsd_break_deleg_cb(struct file_lock *fl)
>>   	bool ret = false;
>>   	struct nfs4_delegation *dp = (struct nfs4_delegation *)fl->fl_owner;
>>   	struct nfs4_file *fp = dp->dl_stid.sc_file;
>> +	struct nfs4_client *clp = dp->dl_stid.sc_client;
>> +	struct nfsd_net *nn;
>>   
>>   	trace_nfsd_cb_recall(&dp->dl_stid);
>>   
>> +	if (try_to_expire_client(clp)) {
>> +		nn = net_generic(clp->net, nfsd_net_id);
>> +		mod_delayed_work(laundry_wq, &nn->laundromat_work, 0);
>> +	}
>> +
>>   	/*
>>   	 * We don't want the locks code to timeout the lease for us;
>>   	 * we'll remove it ourself if a delegation isn't returned
>> @@ -5605,6 +5617,58 @@ static void nfsd4_ssc_expire_umount(struct nfsd_net *nn)
>>   }
>>   #endif
>>   
>> +/*
>> + * place holder for now, no check for lock blockers yet
>> + */
>> +static bool
>> +nfs4_anylock_blockers(struct nfs4_client *clp)
>> +{
>> +	/*
>> +	 * don't want to check for delegation conflict here since
>> +	 * we need the state_lock for it. The laundromat willexpire
>> +	 * COURTESY later when checking for delegation recall timeout.
>> +	 */
>> +	return false;
>> +}
>> +
>> +static bool client_has_state_tmp(struct nfs4_client *clp)
>> +{
>> +	if (!list_empty(&clp->cl_delegations) &&
>> +			!client_has_openowners(clp) &&
>> +			list_empty(&clp->async_copies))
>> +		return true;
>> +	return false;
>> +}
>> +
>> +static void
>> +nfs4_get_client_reaplist(struct nfsd_net *nn, struct list_head *reaplist,
>> +				struct laundry_time *lt)
>> +{
>> +	struct list_head *pos, *next;
>> +	struct nfs4_client *clp;
>> +
>> +	INIT_LIST_HEAD(reaplist);
>> +	spin_lock(&nn->client_lock);
>> +	list_for_each_safe(pos, next, &nn->client_lru) {
>> +		clp = list_entry(pos, struct nfs4_client, cl_lru);
>> +		if (clp->cl_state == NFSD4_EXPIRABLE)
>> +			goto exp_client;
>> +		if (!state_expired(lt, clp->cl_time))
>> +			break;
>> +		clp->cl_state = NFSD4_COURTESY;
>> +		if (!client_has_state_tmp(clp) ||
>> +				ktime_get_boottime_seconds() >=
>> +				(clp->cl_time + NFSD_COURTESY_CLIENT_TIMEOUT))
>> +			goto exp_client;
>> +		if (nfs4_anylock_blockers(clp)) {
>> +exp_client:
>> +			if (!mark_client_expired_locked(clp))
>> +				list_add(&clp->cl_lru, reaplist);
>> +		}
>> +	}
>> +	spin_unlock(&nn->client_lock);
>> +}
>> +
>>   static time64_t
>>   nfs4_laundromat(struct nfsd_net *nn)
>>   {
>> @@ -5627,7 +5691,6 @@ nfs4_laundromat(struct nfsd_net *nn)
>>   		goto out;
>>   	}
>>   	nfsd4_end_grace(nn);
>> -	INIT_LIST_HEAD(&reaplist);
>>   
>>   	spin_lock(&nn->s2s_cp_lock);
>>   	idr_for_each_entry(&nn->s2s_cp_stateids, cps_t, i) {
>> @@ -5637,17 +5700,7 @@ nfs4_laundromat(struct nfsd_net *nn)
>>   			_free_cpntf_state_locked(nn, cps);
>>   	}
>>   	spin_unlock(&nn->s2s_cp_lock);
>> -
>> -	spin_lock(&nn->client_lock);
>> -	list_for_each_safe(pos, next, &nn->client_lru) {
>> -		clp = list_entry(pos, struct nfs4_client, cl_lru);
>> -		if (!state_expired(&lt, clp->cl_time))
>> -			break;
>> -		if (mark_client_expired_locked(clp))
>> -			continue;
>> -		list_add(&clp->cl_lru, &reaplist);
>> -	}
>> -	spin_unlock(&nn->client_lock);
>> +	nfs4_get_client_reaplist(nn, &reaplist, &lt);
>>   	list_for_each_safe(pos, next, &reaplist) {
>>   		clp = list_entry(pos, struct nfs4_client, cl_lru);
>>   		trace_nfsd_clid_purged(&clp->cl_clientid);
>> @@ -5657,6 +5710,7 @@ nfs4_laundromat(struct nfsd_net *nn)
>>   	spin_lock(&state_lock);
>>   	list_for_each_safe(pos, next, &nn->del_recall_lru) {
>>   		dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
>> +		try_to_expire_client(dp->dl_stid.sc_client);
> I don't think this quite works.  First, we're only looping over the
> delegations that have been under recall for the longest, and those
> aren't the only ones that may matter.  Second, just calling
> try_to_expire_client isn't enough, we also need to reschedule the
> laundromat.
>
> It's not the end of the world, we'll just have to wait another lease
> period, but I think we can do better.
>
> How about something like the below?  (Incomplete.)   And then you can
> check cl_delegs_in_recall in nfs4_anylock_blockers.

fix in v24.

-Dai

>
> Otherwise, this patch seems OK to me.
>
> --b.
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 4f45caead507..23041584d84f 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -4780,6 +4780,9 @@ nfsd_break_deleg_cb(struct file_lock *fl)
>   
>   	trace_nfsd_cb_recall(&dp->dl_stid);
>   
> +	dp->dl_recalled = true;
> +	atomic_inc(&clp->cl_delegs_in_recall);
> +
>   	if (!try_to_expire_client(clp)) {
>   		nn = net_generic(clp->net, nfsd_net_id);
>   		mod_delayed_work(laundry_wq, &nn->laundromat_work, 0);
> @@ -4827,9 +4830,14 @@ static int
>   nfsd_change_deleg_cb(struct file_lock *onlist, int arg,
>   		     struct list_head *dispose)
>   {
> -	if (arg & F_UNLCK)
> +	struct nfs4_delegation *dp = (struct nfs4_delegation *)onlist->fl_owner;
> +	struct nfs4_client *clp = dp->dl_stid.sc_client;
> +
> +	if (arg & F_UNLCK) {
> +		if (dp->dl_recalled)
> +			atomic_dec(&clp->cl_delegs_in_recall);
>   		return lease_modify(onlist, arg, dispose);
> -	else
> +	} else
>   		return -EAGAIN;
>   }
>
J.Bruce Fields April 29, 2022, 7:55 p.m. UTC | #5
On Fri, Apr 29, 2022 at 10:21:21AM -0700, dai.ngo@oracle.com wrote:
> 
> On 4/29/22 7:55 AM, J. Bruce Fields wrote:
> >On Thu, Apr 28, 2022 at 12:06:29AM -0700, Dai Ngo wrote:
> >>This patch provides courteous server support for delegation only.
> >>Only expired client with delegation but no conflict and no open
> >>or lock state is allowed to be in COURTESY state.
> >>
> >>Delegation conflict with COURTESY/EXPIRABLE client is resolved by
> >>setting it to EXPIRABLE, queue work for the laundromat and return
> >>delay to the caller. Conflict is resolved when the laudromat runs
> >>and expires the EXIRABLE client while the NFS client retries the
> >>OPEN request. Local thread request that gets conflict is doing the
> >>retry in _break_lease.
> >>
> >>Client in COURTESY or EXPIRABLE state is allowed to reconnect and
> >>continues to have access to its state. Access to the nfs4_client by
> >>the reconnecting thread and the laundromat is serialized via the
> >>client_lock.
> >>
> >>Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> >>---
> >>  fs/nfsd/nfs4state.c | 79 ++++++++++++++++++++++++++++++++++++++++++++---------
> >>  fs/nfsd/nfsd.h      |  1 +
> >>  fs/nfsd/state.h     | 29 ++++++++++++++++++++
> >>  3 files changed, 96 insertions(+), 13 deletions(-)
> >>
> >>diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> >>index 234e852fcdfa..b84ba19c856b 100644
> >>--- a/fs/nfsd/nfs4state.c
> >>+++ b/fs/nfsd/nfs4state.c
> >>@@ -125,6 +125,8 @@ static void free_session(struct nfsd4_session *);
> >>  static const struct nfsd4_callback_ops nfsd4_cb_recall_ops;
> >>  static const struct nfsd4_callback_ops nfsd4_cb_notify_lock_ops;
> >>+static struct workqueue_struct *laundry_wq;
> >>+
> >>  static bool is_session_dead(struct nfsd4_session *ses)
> >>  {
> >>  	return ses->se_flags & NFS4_SESSION_DEAD;
> >>@@ -152,6 +154,7 @@ static __be32 get_client_locked(struct nfs4_client *clp)
> >>  	if (is_client_expired(clp))
> >>  		return nfserr_expired;
> >>  	atomic_inc(&clp->cl_rpc_users);
> >>+	clp->cl_state = NFSD4_ACTIVE;
> >>  	return nfs_ok;
> >>  }
> >>@@ -172,6 +175,7 @@ renew_client_locked(struct nfs4_client *clp)
> >>  	list_move_tail(&clp->cl_lru, &nn->client_lru);
> >>  	clp->cl_time = ktime_get_boottime_seconds();
> >>+	clp->cl_state = NFSD4_ACTIVE;
> >>  }
> >>  static void put_client_renew_locked(struct nfs4_client *clp)
> >>@@ -2004,6 +2008,7 @@ static struct nfs4_client *alloc_client(struct xdr_netobj name)
> >>  	idr_init(&clp->cl_stateids);
> >>  	atomic_set(&clp->cl_rpc_users, 0);
> >>  	clp->cl_cb_state = NFSD4_CB_UNKNOWN;
> >>+	clp->cl_state = NFSD4_ACTIVE;
> >>  	INIT_LIST_HEAD(&clp->cl_idhash);
> >>  	INIT_LIST_HEAD(&clp->cl_openowners);
> >>  	INIT_LIST_HEAD(&clp->cl_delegations);
> >>@@ -4694,9 +4699,16 @@ nfsd_break_deleg_cb(struct file_lock *fl)
> >>  	bool ret = false;
> >>  	struct nfs4_delegation *dp = (struct nfs4_delegation *)fl->fl_owner;
> >>  	struct nfs4_file *fp = dp->dl_stid.sc_file;
> >>+	struct nfs4_client *clp = dp->dl_stid.sc_client;
> >>+	struct nfsd_net *nn;
> >>  	trace_nfsd_cb_recall(&dp->dl_stid);
> >>+	if (try_to_expire_client(clp)) {
> >>+		nn = net_generic(clp->net, nfsd_net_id);
> >>+		mod_delayed_work(laundry_wq, &nn->laundromat_work, 0);
> >>+	}
> >>+
> >>  	/*
> >>  	 * We don't want the locks code to timeout the lease for us;
> >>  	 * we'll remove it ourself if a delegation isn't returned
> >>@@ -5605,6 +5617,58 @@ static void nfsd4_ssc_expire_umount(struct nfsd_net *nn)
> >>  }
> >>  #endif
> >>+/*
> >>+ * place holder for now, no check for lock blockers yet
> >>+ */
> >>+static bool
> >>+nfs4_anylock_blockers(struct nfs4_client *clp)
> >>+{
> >>+	/*
> >>+	 * don't want to check for delegation conflict here since
> >>+	 * we need the state_lock for it. The laundromat willexpire
> >>+	 * COURTESY later when checking for delegation recall timeout.
> >>+	 */
> >>+	return false;
> >>+}
> >>+
> >>+static bool client_has_state_tmp(struct nfs4_client *clp)
> >Why the "_tmp"?
> >
> >>+{
> >>+	if (!list_empty(&clp->cl_delegations) &&
> >>+			!client_has_openowners(clp) &&
> >>+			list_empty(&clp->async_copies))
> >I would have expected
> >
> >	if (!list_empty(&clp->cl_delegations) ||
> >		client_has_openowners(clp) ||
> >		!list_empty(&clp->async_copies))
> 
> In patch 1, we want to allow *only* clients with non-conflict delegation
> to be in COURTESY state, not with opens and locks. So for that, we can not
> use the existing client_has_state (until patch 6), so I just created
> client_has_state_tmp for it.

Got it, so, I recommend just moving this logic into
nfs4_anylock_blockers instead, and replacing the call to
client_has_state_tmp() with a call to client_has_state().

The logic of nfs4_anylock_blockers() is then basically "return true if anyone
might be waiting on this client; and if the client has some class of
state that we don't handle yet, just assume it might have someone
waiting on it."

--b.

> 
> -Dai
> 
> >
> >?--b.
> >
> >>+		return true;
> >>+	return false;
> >>+}
> >>+
> >>+static void
> >>+nfs4_get_client_reaplist(struct nfsd_net *nn, struct list_head *reaplist,
> >>+				struct laundry_time *lt)
> >>+{
> >>+	struct list_head *pos, *next;
> >>+	struct nfs4_client *clp;
> >>+
> >>+	INIT_LIST_HEAD(reaplist);
> >>+	spin_lock(&nn->client_lock);
> >>+	list_for_each_safe(pos, next, &nn->client_lru) {
> >>+		clp = list_entry(pos, struct nfs4_client, cl_lru);
> >>+		if (clp->cl_state == NFSD4_EXPIRABLE)
> >>+			goto exp_client;
> >>+		if (!state_expired(lt, clp->cl_time))
> >>+			break;
> >>+		clp->cl_state = NFSD4_COURTESY;
> >>+		if (!client_has_state_tmp(clp) ||
> >>+				ktime_get_boottime_seconds() >=
> >>+				(clp->cl_time + NFSD_COURTESY_CLIENT_TIMEOUT))
> >>+			goto exp_client;
> >>+		if (nfs4_anylock_blockers(clp)) {
> >>+exp_client:
> >>+			if (!mark_client_expired_locked(clp))
> >>+				list_add(&clp->cl_lru, reaplist);
> >>+		}
> >>+	}
> >>+	spin_unlock(&nn->client_lock);
> >>+}
> >>+
> >>  static time64_t
> >>  nfs4_laundromat(struct nfsd_net *nn)
> >>  {
> >>@@ -5627,7 +5691,6 @@ nfs4_laundromat(struct nfsd_net *nn)
> >>  		goto out;
> >>  	}
> >>  	nfsd4_end_grace(nn);
> >>-	INIT_LIST_HEAD(&reaplist);
> >>  	spin_lock(&nn->s2s_cp_lock);
> >>  	idr_for_each_entry(&nn->s2s_cp_stateids, cps_t, i) {
> >>@@ -5637,17 +5700,7 @@ nfs4_laundromat(struct nfsd_net *nn)
> >>  			_free_cpntf_state_locked(nn, cps);
> >>  	}
> >>  	spin_unlock(&nn->s2s_cp_lock);
> >>-
> >>-	spin_lock(&nn->client_lock);
> >>-	list_for_each_safe(pos, next, &nn->client_lru) {
> >>-		clp = list_entry(pos, struct nfs4_client, cl_lru);
> >>-		if (!state_expired(&lt, clp->cl_time))
> >>-			break;
> >>-		if (mark_client_expired_locked(clp))
> >>-			continue;
> >>-		list_add(&clp->cl_lru, &reaplist);
> >>-	}
> >>-	spin_unlock(&nn->client_lock);
> >>+	nfs4_get_client_reaplist(nn, &reaplist, &lt);
> >>  	list_for_each_safe(pos, next, &reaplist) {
> >>  		clp = list_entry(pos, struct nfs4_client, cl_lru);
> >>  		trace_nfsd_clid_purged(&clp->cl_clientid);
> >>@@ -5657,6 +5710,7 @@ nfs4_laundromat(struct nfsd_net *nn)
> >>  	spin_lock(&state_lock);
> >>  	list_for_each_safe(pos, next, &nn->del_recall_lru) {
> >>  		dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
> >>+		try_to_expire_client(dp->dl_stid.sc_client);
> >>  		if (!state_expired(&lt, dp->dl_time))
> >>  			break;
> >>  		WARN_ON(!unhash_delegation_locked(dp));
> >>@@ -5722,7 +5776,6 @@ nfs4_laundromat(struct nfsd_net *nn)
> >>  	return max_t(time64_t, lt.new_timeo, NFSD_LAUNDROMAT_MINTIMEOUT);
> >>  }
> >>-static struct workqueue_struct *laundry_wq;
> >>  static void laundromat_main(struct work_struct *);
> >>  static void
> >>diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
> >>index 4fc1fd639527..23996c6ca75e 100644
> >>--- a/fs/nfsd/nfsd.h
> >>+++ b/fs/nfsd/nfsd.h
> >>@@ -336,6 +336,7 @@ void		nfsd_lockd_shutdown(void);
> >>  #define COMPOUND_ERR_SLACK_SPACE	16     /* OP_SETATTR */
> >>  #define NFSD_LAUNDROMAT_MINTIMEOUT      1   /* seconds */
> >>+#define	NFSD_COURTESY_CLIENT_TIMEOUT	(24 * 60 * 60)	/* seconds */
> >>  /*
> >>   * The following attributes are currently not supported by the NFSv4 server:
> >>diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
> >>index 95457cfd37fc..bd15f2863823 100644
> >>--- a/fs/nfsd/state.h
> >>+++ b/fs/nfsd/state.h
> >>@@ -283,6 +283,28 @@ struct nfsd4_sessionid {
> >>  #define HEXDIR_LEN     33 /* hex version of 16 byte md5 of cl_name plus '\0' */
> >>  /*
> >>+ *       State                Meaning                  Where set
> >>+ * --------------------------------------------------------------------------
> >>+ * | NFSD4_ACTIVE      | Confirmed, active    | Default                     |
> >>+ * |------------------- ----------------------------------------------------|
> >>+ * | NFSD4_COURTESY    | Courtesy state.      | nfs4_get_client_reaplist    |
> >>+ * |                   | Lease/lock/share     |                             |
> >>+ * |                   | reservation conflict |                             |
> >>+ * |                   | can cause Courtesy   |                             |
> >>+ * |                   | client to be expired |                             |
> >>+ * |------------------------------------------------------------------------|
> >>+ * | NFSD4_EXPIRABLE   | Courtesy client to be| nfs4_laundromat             |
> >>+ * |                   | expired by Laundromat| try_to_expire_client        |
> >>+ * |                   | due to conflict      |                             |
> >>+ * |------------------------------------------------------------------------|
> >>+ */
> >>+enum {
> >>+	NFSD4_ACTIVE = 0,
> >>+	NFSD4_COURTESY,
> >>+	NFSD4_EXPIRABLE,
> >>+};
> >>+
> >>+/*
> >>   * struct nfs4_client - one per client.  Clientids live here.
> >>   *
> >>   * The initial object created by an NFS client using SETCLIENTID (for NFSv4.0)
> >>@@ -385,6 +407,8 @@ struct nfs4_client {
> >>  	struct list_head	async_copies;	/* list of async copies */
> >>  	spinlock_t		async_lock;	/* lock for async copies */
> >>  	atomic_t		cl_cb_inflight;	/* Outstanding callbacks */
> >>+
> >>+	unsigned int		cl_state;
> >>  };
> >>  /* struct nfs4_client_reset
> >>@@ -702,4 +726,9 @@ extern void nfsd4_client_record_remove(struct nfs4_client *clp);
> >>  extern int nfsd4_client_record_check(struct nfs4_client *clp);
> >>  extern void nfsd4_record_grace_done(struct nfsd_net *nn);
> >>+static inline bool try_to_expire_client(struct nfs4_client *clp)
> >>+{
> >>+	cmpxchg(&clp->cl_state, NFSD4_COURTESY, NFSD4_EXPIRABLE);
> >>+	return clp->cl_state == NFSD4_EXPIRABLE;
> >>+}
> >>  #endif   /* NFSD4_STATE_H */
> >>-- 
> >>2.9.5
J.Bruce Fields April 29, 2022, 7:59 p.m. UTC | #6
On Fri, Apr 29, 2022 at 03:55:10PM -0400, J. Bruce Fields wrote:
> On Fri, Apr 29, 2022 at 10:21:21AM -0700, dai.ngo@oracle.com wrote:
> > 
> > On 4/29/22 7:55 AM, J. Bruce Fields wrote:
> > >On Thu, Apr 28, 2022 at 12:06:29AM -0700, Dai Ngo wrote:
> > >>+static bool client_has_state_tmp(struct nfs4_client *clp)
> > >Why the "_tmp"?
> > >
> > >>+{
> > >>+	if (!list_empty(&clp->cl_delegations) &&
> > >>+			!client_has_openowners(clp) &&
> > >>+			list_empty(&clp->async_copies))
> > >I would have expected
> > >
> > >	if (!list_empty(&clp->cl_delegations) ||
> > >		client_has_openowners(clp) ||
> > >		!list_empty(&clp->async_copies))
> > 
> > In patch 1, we want to allow *only* clients with non-conflict delegation
> > to be in COURTESY state, not with opens and locks. So for that, we can not
> > use the existing client_has_state (until patch 6), so I just created
> > client_has_state_tmp for it.
> 
> Got it, so, I recommend just moving this logic into
> nfs4_anylock_blockers instead, and replacing the call to
> client_has_state_tmp() with a call to client_has_state().
> 
> The logic of nfs4_anylock_blockers() is then basically "return true if anyone
> might be waiting on this client; and if the client has some class of
> state that we don't handle yet, just assume it might have someone
> waiting on it."

And, yeah, the end result is probably the same, but this would just make
the patches easier to read.

--b.
diff mbox series

Patch

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 234e852fcdfa..b84ba19c856b 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -125,6 +125,8 @@  static void free_session(struct nfsd4_session *);
 static const struct nfsd4_callback_ops nfsd4_cb_recall_ops;
 static const struct nfsd4_callback_ops nfsd4_cb_notify_lock_ops;
 
+static struct workqueue_struct *laundry_wq;
+
 static bool is_session_dead(struct nfsd4_session *ses)
 {
 	return ses->se_flags & NFS4_SESSION_DEAD;
@@ -152,6 +154,7 @@  static __be32 get_client_locked(struct nfs4_client *clp)
 	if (is_client_expired(clp))
 		return nfserr_expired;
 	atomic_inc(&clp->cl_rpc_users);
+	clp->cl_state = NFSD4_ACTIVE;
 	return nfs_ok;
 }
 
@@ -172,6 +175,7 @@  renew_client_locked(struct nfs4_client *clp)
 
 	list_move_tail(&clp->cl_lru, &nn->client_lru);
 	clp->cl_time = ktime_get_boottime_seconds();
+	clp->cl_state = NFSD4_ACTIVE;
 }
 
 static void put_client_renew_locked(struct nfs4_client *clp)
@@ -2004,6 +2008,7 @@  static struct nfs4_client *alloc_client(struct xdr_netobj name)
 	idr_init(&clp->cl_stateids);
 	atomic_set(&clp->cl_rpc_users, 0);
 	clp->cl_cb_state = NFSD4_CB_UNKNOWN;
+	clp->cl_state = NFSD4_ACTIVE;
 	INIT_LIST_HEAD(&clp->cl_idhash);
 	INIT_LIST_HEAD(&clp->cl_openowners);
 	INIT_LIST_HEAD(&clp->cl_delegations);
@@ -4694,9 +4699,16 @@  nfsd_break_deleg_cb(struct file_lock *fl)
 	bool ret = false;
 	struct nfs4_delegation *dp = (struct nfs4_delegation *)fl->fl_owner;
 	struct nfs4_file *fp = dp->dl_stid.sc_file;
+	struct nfs4_client *clp = dp->dl_stid.sc_client;
+	struct nfsd_net *nn;
 
 	trace_nfsd_cb_recall(&dp->dl_stid);
 
+	if (try_to_expire_client(clp)) {
+		nn = net_generic(clp->net, nfsd_net_id);
+		mod_delayed_work(laundry_wq, &nn->laundromat_work, 0);
+	}
+
 	/*
 	 * We don't want the locks code to timeout the lease for us;
 	 * we'll remove it ourself if a delegation isn't returned
@@ -5605,6 +5617,58 @@  static void nfsd4_ssc_expire_umount(struct nfsd_net *nn)
 }
 #endif
 
+/*
+ * place holder for now, no check for lock blockers yet
+ */
+static bool
+nfs4_anylock_blockers(struct nfs4_client *clp)
+{
+	/*
+	 * don't want to check for delegation conflict here since
+	 * we need the state_lock for it. The laundromat willexpire
+	 * COURTESY later when checking for delegation recall timeout.
+	 */
+	return false;
+}
+
+static bool client_has_state_tmp(struct nfs4_client *clp)
+{
+	if (!list_empty(&clp->cl_delegations) &&
+			!client_has_openowners(clp) &&
+			list_empty(&clp->async_copies))
+		return true;
+	return false;
+}
+
+static void
+nfs4_get_client_reaplist(struct nfsd_net *nn, struct list_head *reaplist,
+				struct laundry_time *lt)
+{
+	struct list_head *pos, *next;
+	struct nfs4_client *clp;
+
+	INIT_LIST_HEAD(reaplist);
+	spin_lock(&nn->client_lock);
+	list_for_each_safe(pos, next, &nn->client_lru) {
+		clp = list_entry(pos, struct nfs4_client, cl_lru);
+		if (clp->cl_state == NFSD4_EXPIRABLE)
+			goto exp_client;
+		if (!state_expired(lt, clp->cl_time))
+			break;
+		clp->cl_state = NFSD4_COURTESY;
+		if (!client_has_state_tmp(clp) ||
+				ktime_get_boottime_seconds() >=
+				(clp->cl_time + NFSD_COURTESY_CLIENT_TIMEOUT))
+			goto exp_client;
+		if (nfs4_anylock_blockers(clp)) {
+exp_client:
+			if (!mark_client_expired_locked(clp))
+				list_add(&clp->cl_lru, reaplist);
+		}
+	}
+	spin_unlock(&nn->client_lock);
+}
+
 static time64_t
 nfs4_laundromat(struct nfsd_net *nn)
 {
@@ -5627,7 +5691,6 @@  nfs4_laundromat(struct nfsd_net *nn)
 		goto out;
 	}
 	nfsd4_end_grace(nn);
-	INIT_LIST_HEAD(&reaplist);
 
 	spin_lock(&nn->s2s_cp_lock);
 	idr_for_each_entry(&nn->s2s_cp_stateids, cps_t, i) {
@@ -5637,17 +5700,7 @@  nfs4_laundromat(struct nfsd_net *nn)
 			_free_cpntf_state_locked(nn, cps);
 	}
 	spin_unlock(&nn->s2s_cp_lock);
-
-	spin_lock(&nn->client_lock);
-	list_for_each_safe(pos, next, &nn->client_lru) {
-		clp = list_entry(pos, struct nfs4_client, cl_lru);
-		if (!state_expired(&lt, clp->cl_time))
-			break;
-		if (mark_client_expired_locked(clp))
-			continue;
-		list_add(&clp->cl_lru, &reaplist);
-	}
-	spin_unlock(&nn->client_lock);
+	nfs4_get_client_reaplist(nn, &reaplist, &lt);
 	list_for_each_safe(pos, next, &reaplist) {
 		clp = list_entry(pos, struct nfs4_client, cl_lru);
 		trace_nfsd_clid_purged(&clp->cl_clientid);
@@ -5657,6 +5710,7 @@  nfs4_laundromat(struct nfsd_net *nn)
 	spin_lock(&state_lock);
 	list_for_each_safe(pos, next, &nn->del_recall_lru) {
 		dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
+		try_to_expire_client(dp->dl_stid.sc_client);
 		if (!state_expired(&lt, dp->dl_time))
 			break;
 		WARN_ON(!unhash_delegation_locked(dp));
@@ -5722,7 +5776,6 @@  nfs4_laundromat(struct nfsd_net *nn)
 	return max_t(time64_t, lt.new_timeo, NFSD_LAUNDROMAT_MINTIMEOUT);
 }
 
-static struct workqueue_struct *laundry_wq;
 static void laundromat_main(struct work_struct *);
 
 static void
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 4fc1fd639527..23996c6ca75e 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -336,6 +336,7 @@  void		nfsd_lockd_shutdown(void);
 #define COMPOUND_ERR_SLACK_SPACE	16     /* OP_SETATTR */
 
 #define NFSD_LAUNDROMAT_MINTIMEOUT      1   /* seconds */
+#define	NFSD_COURTESY_CLIENT_TIMEOUT	(24 * 60 * 60)	/* seconds */
 
 /*
  * The following attributes are currently not supported by the NFSv4 server:
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index 95457cfd37fc..bd15f2863823 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -283,6 +283,28 @@  struct nfsd4_sessionid {
 #define HEXDIR_LEN     33 /* hex version of 16 byte md5 of cl_name plus '\0' */
 
 /*
+ *       State                Meaning                  Where set
+ * --------------------------------------------------------------------------
+ * | NFSD4_ACTIVE      | Confirmed, active    | Default                     |
+ * |------------------- ----------------------------------------------------|
+ * | NFSD4_COURTESY    | Courtesy state.      | nfs4_get_client_reaplist    |
+ * |                   | Lease/lock/share     |                             |
+ * |                   | reservation conflict |                             |
+ * |                   | can cause Courtesy   |                             |
+ * |                   | client to be expired |                             |
+ * |------------------------------------------------------------------------|
+ * | NFSD4_EXPIRABLE   | Courtesy client to be| nfs4_laundromat             |
+ * |                   | expired by Laundromat| try_to_expire_client        |
+ * |                   | due to conflict      |                             |
+ * |------------------------------------------------------------------------|
+ */
+enum {
+	NFSD4_ACTIVE = 0,
+	NFSD4_COURTESY,
+	NFSD4_EXPIRABLE,
+};
+
+/*
  * struct nfs4_client - one per client.  Clientids live here.
  *
  * The initial object created by an NFS client using SETCLIENTID (for NFSv4.0)
@@ -385,6 +407,8 @@  struct nfs4_client {
 	struct list_head	async_copies;	/* list of async copies */
 	spinlock_t		async_lock;	/* lock for async copies */
 	atomic_t		cl_cb_inflight;	/* Outstanding callbacks */
+
+	unsigned int		cl_state;
 };
 
 /* struct nfs4_client_reset
@@ -702,4 +726,9 @@  extern void nfsd4_client_record_remove(struct nfs4_client *clp);
 extern int nfsd4_client_record_check(struct nfs4_client *clp);
 extern void nfsd4_record_grace_done(struct nfsd_net *nn);
 
+static inline bool try_to_expire_client(struct nfs4_client *clp)
+{
+	cmpxchg(&clp->cl_state, NFSD4_COURTESY, NFSD4_EXPIRABLE);
+	return clp->cl_state == NFSD4_EXPIRABLE;
+}
 #endif   /* NFSD4_STATE_H */