[for-6.16-final PATCH 7/9] Revert "nfs_localio: use cmpxchg() to install new nfs_file_localio"

[Mike Snitzer <snitzer@xxxxxxxxxx>]

This reverts commit 9fccbbec13a73ae0e75448a00e20dadc8c511c8c.

Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
---
 fs/nfs/localio.c           | 11 ++++++++---
 fs/nfs_common/nfslocalio.c | 39 +++++++++++++++++++++-----------------
 2 files changed, 30 insertions(+), 20 deletions(-)

diff --git a/fs/nfs/localio.c b/fs/nfs/localio.c
index 7a33da477da3..a4bacd9a5052 100644
--- a/fs/nfs/localio.c
+++ b/fs/nfs/localio.c
@@ -282,9 +282,14 @@ nfs_local_open_fh(struct nfs_client *clp, const struct cred *cred,
 			return NULL;
 		rcu_read_lock();
 		/* try to swap in the pointer */
-		nf = unrcu_pointer(cmpxchg(pnf, NULL, RCU_INITIALIZER(new)));
-		if (!nf)
-			swap(nf, new);
+		spin_lock(&clp->cl_uuid.lock);
+		nf = rcu_dereference_protected(*pnf, 1);
+		if (!nf) {
+			nf = new;
+			new = NULL;
+			rcu_assign_pointer(*pnf, nf);
+		}
+		spin_unlock(&clp->cl_uuid.lock);
 	}
 	nf = nfs_local_file_get(nf);
 	rcu_read_unlock();
diff --git a/fs/nfs_common/nfslocalio.c b/fs/nfs_common/nfslocalio.c
index bdf251332b6b..6a0bdea6d644 100644
--- a/fs/nfs_common/nfslocalio.c
+++ b/fs/nfs_common/nfslocalio.c
@@ -273,8 +273,8 @@ EXPORT_SYMBOL_GPL(nfs_open_local_fh);
 
 void nfs_close_local_fh(struct nfs_file_localio *nfl)
 {
-	struct nfsd_file *ro_nf;
-	struct nfsd_file *rw_nf;
+	struct nfsd_file *ro_nf = NULL;
+	struct nfsd_file *rw_nf = NULL;
 	nfs_uuid_t *nfs_uuid;
 
 	rcu_read_lock();
@@ -285,23 +285,28 @@ void nfs_close_local_fh(struct nfs_file_localio *nfl)
 		return;
 	}
 
-	ro_nf = unrcu_pointer(xchg(&nfl->ro_file, NULL));
-	rw_nf = unrcu_pointer(xchg(&nfl->rw_file, NULL));
+	ro_nf = rcu_access_pointer(nfl->ro_file);
+	rw_nf = rcu_access_pointer(nfl->rw_file);
+	if (ro_nf || rw_nf) {
+		spin_lock(&nfs_uuid->lock);
+		if (ro_nf)
+			ro_nf = rcu_dereference_protected(xchg(&nfl->ro_file, NULL), 1);
+		if (rw_nf)
+			rw_nf = rcu_dereference_protected(xchg(&nfl->rw_file, NULL), 1);
 
-	spin_lock(&nfs_uuid->lock);
-	/* Remove nfl from nfs_uuid->files list */
-	list_del_init(&nfl->list);
-	spin_unlock(&nfs_uuid->lock);
+		/* Remove nfl from nfs_uuid->files list */
+		RCU_INIT_POINTER(nfl->nfs_uuid, NULL);
+		list_del_init(&nfl->list);
+		spin_unlock(&nfs_uuid->lock);
+		rcu_read_unlock();
+
+		if (ro_nf)
+			nfs_to_nfsd_file_put_local(ro_nf);
+		if (rw_nf)
+			nfs_to_nfsd_file_put_local(rw_nf);
+		return;
+	}
 	rcu_read_unlock();
-	/* Now we can allow racing nfs_close_local_fh() to
-	 * skip the locking.
-	 */
-	RCU_INIT_POINTER(nfl->nfs_uuid, NULL);
-
-	if (ro_nf)
-		nfs_to_nfsd_file_put_local(ro_nf);
-	if (rw_nf)
-		nfs_to_nfsd_file_put_local(rw_nf);
 }
 EXPORT_SYMBOL_GPL(nfs_close_local_fh);
 
-- 
2.44.0