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From:   Dai Ngo <dai.ngo@oracle.com>
To:     chuck.lever@oracle.com, bfields@fieldses.org
Cc:     jlayton@redhat.com, viro@zeniv.linux.org.uk,
        linux-nfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: [PATCH RFC v22 6/7] NFSD: add support for lock conflict to courteous server
Date:   Wed, 27 Apr 2022 01:52:52 -0700
Message-Id: <1651049573-29552-7-git-send-email-dai.ngo@oracle.com>
In-Reply-To: <1651049573-29552-1-git-send-email-dai.ngo@oracle.com>
References: <1651049573-29552-1-git-send-email-dai.ngo@oracle.com>
Precedence: bulk

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);
+}
+
 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