diff mbox series

[RFC,v22,6/7] NFSD: add support for lock conflict to courteous server

Message ID 1651049573-29552-7-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 27, 2022, 8:52 a.m. UTC
This patch allows expired client with lock state to be in COURTESY
state. Lock conflict with COURTESY client is resolved by the fs/lock
code using the lm_lock_expirable and lm_expire_lock callback in the
struct lock_manager_operations.

If conflict client is in COURTESY state, set it to EXPIRABLE and
schedule the laundromat to run immediately to expire the client. The
callback lm_expire_lock waits for the laundromat to flush its work
queue before returning to caller.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
 fs/nfsd/nfs4state.c | 82 +++++++++++++++++++++++++++++++++--------------------
 1 file changed, 52 insertions(+), 30 deletions(-)

Comments

Dai Ngo April 27, 2022, 6:50 p.m. UTC | #1
> +/* return pointer to struct nfs4_client if client is expirable */
> +static void *
> +nfsd4_lm_lock_expirable(struct file_lock *cfl)
> +{
> +	struct nfs4_lockowner *lo = (struct nfs4_lockowner *)cfl->fl_owner;
> +	struct nfs4_client *clp = lo->lo_owner.so_client;
> +
> +	if (try_to_expire_client(clp))

I dropped the mod_delayed_work here, will add it back.

> +		return clp;
> +	return NULL;
> +}

-Dai
J. Bruce Fields April 28, 2022, 2:05 a.m. UTC | #2
On Wed, Apr 27, 2022 at 01:52:52AM -0700, Dai Ngo wrote:
> This patch allows expired client with lock state to be in COURTESY
> state. Lock conflict with COURTESY client is resolved by the fs/lock
> code using the lm_lock_expirable and lm_expire_lock callback in the
> struct lock_manager_operations.
> 
> If conflict client is in COURTESY state, set it to EXPIRABLE and
> schedule the laundromat to run immediately to expire the client. The
> callback lm_expire_lock waits for the laundromat to flush its work
> queue before returning to caller.
> 
> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> ---
>  fs/nfsd/nfs4state.c | 82 +++++++++++++++++++++++++++++++++--------------------
>  1 file changed, 52 insertions(+), 30 deletions(-)
> 
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 55ecf5da25fe..9b1134d823bb 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -5705,11 +5705,31 @@ static void nfsd4_ssc_expire_umount(struct nfsd_net *nn)
>  }
>  #endif
>  
> +/* Check if any lock belonging to this lockowner has any blockers */
>  static bool
> -nfs4_has_any_locks(struct nfs4_client *clp)
> +nfs4_lockowner_has_blockers(struct nfs4_lockowner *lo)
> +{
> +	struct file_lock_context *ctx;
> +	struct nfs4_ol_stateid *stp;
> +	struct nfs4_file *nf;
> +
> +	list_for_each_entry(stp, &lo->lo_owner.so_stateids, st_perstateowner) {
> +		nf = stp->st_stid.sc_file;
> +		ctx = nf->fi_inode->i_flctx;
> +		if (!ctx)
> +			continue;
> +		if (locks_owner_has_blockers(ctx, lo))
> +			return true;
> +	}
> +	return false;
> +}
> +
> +static bool
> +nfs4_anylock_blockers(struct nfs4_client *clp)
>  {
>  	int i;
>  	struct nfs4_stateowner *so;
> +	struct nfs4_lockowner *lo;
>  
>  	spin_lock(&clp->cl_lock);
>  	for (i = 0; i < OWNER_HASH_SIZE; i++) {
> @@ -5717,40 +5737,17 @@ nfs4_has_any_locks(struct nfs4_client *clp)
>  				so_strhash) {
>  			if (so->so_is_open_owner)
>  				continue;
> -			spin_unlock(&clp->cl_lock);
> -			return true;
> +			lo = lockowner(so);
> +			if (nfs4_lockowner_has_blockers(lo)) {
> +				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
> -	 * 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)
> @@ -5767,7 +5764,7 @@ nfs4_get_client_reaplist(struct nfsd_net *nn, struct list_head *reaplist,
>  			goto exp_client;
>  		if (!state_expired(lt, clp->cl_time))
>  			break;
> -		if (!client_has_state_tmp(clp))
> +		if (!client_has_state(clp))
>  			goto exp_client;
>  		cour = (clp->cl_state == NFSD4_COURTESY);
>  		if (cour && ktime_get_boottime_seconds() >=
> @@ -6722,6 +6719,28 @@ nfsd4_lm_put_owner(fl_owner_t owner)
>  		nfs4_put_stateowner(&lo->lo_owner);
>  }
>  
> +/* return pointer to struct nfs4_client if client is expirable */
> +static void *
> +nfsd4_lm_lock_expirable(struct file_lock *cfl)
> +{
> +	struct nfs4_lockowner *lo = (struct nfs4_lockowner *)cfl->fl_owner;
> +	struct nfs4_client *clp = lo->lo_owner.so_client;
> +
> +	if (!try_to_expire_client(clp))
> +		return clp;
> +	return NULL;
> +}
> +
> +/* schedule laundromat to run immediately and wait for it to complete */
> +static void
> +nfsd4_lm_expire_lock(void *data)
> +{
> +	struct nfs4_client *clp = (struct nfs4_client *)data;
> +	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
> +
> +	flush_workqueue(laundry_wq);

Note we don't actually end up using the nfsd_net, or the argument to
lm_lock_expirable.  This was a mistake in my original sketch.  See

	https://lore.kernel.org/linux-nfs/20220417190727.GA18120@fieldses.org/

	"Correction: I forgot that the laundromat is global, not
	per-net.  So, we can skip the put_net/get_net.  Also,
	lm_lock_expirable can just return bool instead of void *, and
	lm_expire_lock needs no arguments."

--b.

> +}
> +
>  static void
>  nfsd4_lm_notify(struct file_lock *fl)
>  {
> @@ -6748,9 +6767,12 @@ nfsd4_lm_notify(struct file_lock *fl)
>  }
>  
>  static const struct lock_manager_operations nfsd_posix_mng_ops  = {
> +	.lm_mod_owner = THIS_MODULE,
>  	.lm_notify = nfsd4_lm_notify,
>  	.lm_get_owner = nfsd4_lm_get_owner,
>  	.lm_put_owner = nfsd4_lm_put_owner,
> +	.lm_lock_expirable = nfsd4_lm_lock_expirable,
> +	.lm_expire_lock = nfsd4_lm_expire_lock,
>  };
>  
>  static inline void
> -- 
> 2.9.5
Dai Ngo April 28, 2022, 3:47 a.m. UTC | #3
On 4/27/22 7:05 PM, J. Bruce Fields wrote:
> On Wed, Apr 27, 2022 at 01:52:52AM -0700, Dai Ngo wrote:
>> This patch allows expired client with lock state to be in COURTESY
>> state. Lock conflict with COURTESY client is resolved by the fs/lock
>> code using the lm_lock_expirable and lm_expire_lock callback in the
>> struct lock_manager_operations.
>>
>> If conflict client is in COURTESY state, set it to EXPIRABLE and
>> schedule the laundromat to run immediately to expire the client. The
>> callback lm_expire_lock waits for the laundromat to flush its work
>> queue before returning to caller.
>>
>> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
>> ---
>>   fs/nfsd/nfs4state.c | 82 +++++++++++++++++++++++++++++++++--------------------
>>   1 file changed, 52 insertions(+), 30 deletions(-)
>>
>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>> index 55ecf5da25fe..9b1134d823bb 100644
>> --- a/fs/nfsd/nfs4state.c
>> +++ b/fs/nfsd/nfs4state.c
>> @@ -5705,11 +5705,31 @@ static void nfsd4_ssc_expire_umount(struct nfsd_net *nn)
>>   }
>>   #endif
>>   
>> +/* Check if any lock belonging to this lockowner has any blockers */
>>   static bool
>> -nfs4_has_any_locks(struct nfs4_client *clp)
>> +nfs4_lockowner_has_blockers(struct nfs4_lockowner *lo)
>> +{
>> +	struct file_lock_context *ctx;
>> +	struct nfs4_ol_stateid *stp;
>> +	struct nfs4_file *nf;
>> +
>> +	list_for_each_entry(stp, &lo->lo_owner.so_stateids, st_perstateowner) {
>> +		nf = stp->st_stid.sc_file;
>> +		ctx = nf->fi_inode->i_flctx;
>> +		if (!ctx)
>> +			continue;
>> +		if (locks_owner_has_blockers(ctx, lo))
>> +			return true;
>> +	}
>> +	return false;
>> +}
>> +
>> +static bool
>> +nfs4_anylock_blockers(struct nfs4_client *clp)
>>   {
>>   	int i;
>>   	struct nfs4_stateowner *so;
>> +	struct nfs4_lockowner *lo;
>>   
>>   	spin_lock(&clp->cl_lock);
>>   	for (i = 0; i < OWNER_HASH_SIZE; i++) {
>> @@ -5717,40 +5737,17 @@ nfs4_has_any_locks(struct nfs4_client *clp)
>>   				so_strhash) {
>>   			if (so->so_is_open_owner)
>>   				continue;
>> -			spin_unlock(&clp->cl_lock);
>> -			return true;
>> +			lo = lockowner(so);
>> +			if (nfs4_lockowner_has_blockers(lo)) {
>> +				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
>> -	 * 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)
>> @@ -5767,7 +5764,7 @@ nfs4_get_client_reaplist(struct nfsd_net *nn, struct list_head *reaplist,
>>   			goto exp_client;
>>   		if (!state_expired(lt, clp->cl_time))
>>   			break;
>> -		if (!client_has_state_tmp(clp))
>> +		if (!client_has_state(clp))
>>   			goto exp_client;
>>   		cour = (clp->cl_state == NFSD4_COURTESY);
>>   		if (cour && ktime_get_boottime_seconds() >=
>> @@ -6722,6 +6719,28 @@ nfsd4_lm_put_owner(fl_owner_t owner)
>>   		nfs4_put_stateowner(&lo->lo_owner);
>>   }
>>   
>> +/* return pointer to struct nfs4_client if client is expirable */
>> +static void *
>> +nfsd4_lm_lock_expirable(struct file_lock *cfl)
>> +{
>> +	struct nfs4_lockowner *lo = (struct nfs4_lockowner *)cfl->fl_owner;
>> +	struct nfs4_client *clp = lo->lo_owner.so_client;
>> +
>> +	if (!try_to_expire_client(clp))
>> +		return clp;
>> +	return NULL;
>> +}
>> +
>> +/* schedule laundromat to run immediately and wait for it to complete */
>> +static void
>> +nfsd4_lm_expire_lock(void *data)
>> +{
>> +	struct nfs4_client *clp = (struct nfs4_client *)data;
>> +	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
>> +
>> +	flush_workqueue(laundry_wq);
> Note we don't actually end up using the nfsd_net, or the argument to
> lm_lock_expirable.  This was a mistake in my original sketch.  See
>
> 	https://lore.kernel.org/linux-nfs/20220417190727.GA18120@fieldses.org/
>
> 	"Correction: I forgot that the laundromat is global, not
> 	per-net.  So, we can skip the put_net/get_net.  Also,
> 	lm_lock_expirable can just return bool instead of void *, and
> 	lm_expire_lock needs no arguments."

ok. I'll make the adjustment.

-Dai

>
> --b.
>
>> +}
>> +
>>   static void
>>   nfsd4_lm_notify(struct file_lock *fl)
>>   {
>> @@ -6748,9 +6767,12 @@ nfsd4_lm_notify(struct file_lock *fl)
>>   }
>>   
>>   static const struct lock_manager_operations nfsd_posix_mng_ops  = {
>> +	.lm_mod_owner = THIS_MODULE,
>>   	.lm_notify = nfsd4_lm_notify,
>>   	.lm_get_owner = nfsd4_lm_get_owner,
>>   	.lm_put_owner = nfsd4_lm_put_owner,
>> +	.lm_lock_expirable = nfsd4_lm_lock_expirable,
>> +	.lm_expire_lock = nfsd4_lm_expire_lock,
>>   };
>>   
>>   static inline void
>> -- 
>> 2.9.5
diff mbox series

Patch

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 55ecf5da25fe..9b1134d823bb 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -5705,11 +5705,31 @@  static void nfsd4_ssc_expire_umount(struct nfsd_net *nn)
 }
 #endif
 
+/* Check if any lock belonging to this lockowner has any blockers */
 static bool
-nfs4_has_any_locks(struct nfs4_client *clp)
+nfs4_lockowner_has_blockers(struct nfs4_lockowner *lo)
+{
+	struct file_lock_context *ctx;
+	struct nfs4_ol_stateid *stp;
+	struct nfs4_file *nf;
+
+	list_for_each_entry(stp, &lo->lo_owner.so_stateids, st_perstateowner) {
+		nf = stp->st_stid.sc_file;
+		ctx = nf->fi_inode->i_flctx;
+		if (!ctx)
+			continue;
+		if (locks_owner_has_blockers(ctx, lo))
+			return true;
+	}
+	return false;
+}
+
+static bool
+nfs4_anylock_blockers(struct nfs4_client *clp)
 {
 	int i;
 	struct nfs4_stateowner *so;
+	struct nfs4_lockowner *lo;
 
 	spin_lock(&clp->cl_lock);
 	for (i = 0; i < OWNER_HASH_SIZE; i++) {
@@ -5717,40 +5737,17 @@  nfs4_has_any_locks(struct nfs4_client *clp)
 				so_strhash) {
 			if (so->so_is_open_owner)
 				continue;
-			spin_unlock(&clp->cl_lock);
-			return true;
+			lo = lockowner(so);
+			if (nfs4_lockowner_has_blockers(lo)) {
+				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
-	 * 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)
@@ -5767,7 +5764,7 @@  nfs4_get_client_reaplist(struct nfsd_net *nn, struct list_head *reaplist,
 			goto exp_client;
 		if (!state_expired(lt, clp->cl_time))
 			break;
-		if (!client_has_state_tmp(clp))
+		if (!client_has_state(clp))
 			goto exp_client;
 		cour = (clp->cl_state == NFSD4_COURTESY);
 		if (cour && ktime_get_boottime_seconds() >=
@@ -6722,6 +6719,28 @@  nfsd4_lm_put_owner(fl_owner_t owner)
 		nfs4_put_stateowner(&lo->lo_owner);
 }
 
+/* return pointer to struct nfs4_client if client is expirable */
+static void *
+nfsd4_lm_lock_expirable(struct file_lock *cfl)
+{
+	struct nfs4_lockowner *lo = (struct nfs4_lockowner *)cfl->fl_owner;
+	struct nfs4_client *clp = lo->lo_owner.so_client;
+
+	if (!try_to_expire_client(clp))
+		return clp;
+	return NULL;
+}
+
+/* schedule laundromat to run immediately and wait for it to complete */
+static void
+nfsd4_lm_expire_lock(void *data)
+{
+	struct nfs4_client *clp = (struct nfs4_client *)data;
+	struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
+
+	flush_workqueue(laundry_wq);
+}
+
 static void
 nfsd4_lm_notify(struct file_lock *fl)
 {
@@ -6748,9 +6767,12 @@  nfsd4_lm_notify(struct file_lock *fl)
 }
 
 static const struct lock_manager_operations nfsd_posix_mng_ops  = {
+	.lm_mod_owner = THIS_MODULE,
 	.lm_notify = nfsd4_lm_notify,
 	.lm_get_owner = nfsd4_lm_get_owner,
 	.lm_put_owner = nfsd4_lm_put_owner,
+	.lm_lock_expirable = nfsd4_lm_lock_expirable,
+	.lm_expire_lock = nfsd4_lm_expire_lock,
 };
 
 static inline void