nfs: probe for LOCALIO when v4 client reconnects to server

Introduce nfs_local_probe_async() for the NFS client to initiate
if/when it reconnects with server. For NFSv4 it is a simple matter to
call nfs_local_probe_async() from nfs4_do_reclaim (during NFSv4
grace).

Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Anna Schumaker <anna.schumaker@oracle.com>

Author: Mike Snitzer

fs/nfs/client.c

@@ -186,6 +186,7 @@ struct nfs_client *nfs_alloc_client(const struct nfs_client_initdata *cl_init)
 	seqlock_init(&clp->cl_boot_lock);
 	ktime_get_real_ts64(&clp->cl_nfssvc_boot);
 	nfs_uuid_init(&clp->cl_uuid);
+	INIT_WORK(&clp->cl_local_probe_work, nfs_local_probe_async_work);
 #endif /* CONFIG_NFS_LOCALIO */
 
 	clp->cl_principal = "*";

fs/nfs/internal.h

@@ -456,6 +456,8 @@ extern int nfs_wait_bit_killable(struct wait_bit_key *key, int mode);
 #if IS_ENABLED(CONFIG_NFS_LOCALIO)
 /* localio.c */
 extern void nfs_local_probe(struct nfs_client *);
+extern void nfs_local_probe_async(struct nfs_client *);
+extern void nfs_local_probe_async_work(struct work_struct *);
 extern struct nfsd_file *nfs_local_open_fh(struct nfs_client *,
 					   const struct cred *,
 					   struct nfs_fh *,
@@ -472,6 +474,7 @@ extern bool nfs_server_is_local(const struct nfs_client *clp);
 
 #else /* CONFIG_NFS_LOCALIO */
 static inline void nfs_local_probe(struct nfs_client *clp) {}
+static inline void nfs_local_probe_async(struct nfs_client *clp) {}
 static inline struct nfsd_file *
 nfs_local_open_fh(struct nfs_client *clp, const struct cred *cred,
 		  struct nfs_fh *fh, struct nfs_file_localio *nfl,

fs/nfs/localio.c

@@ -193,6 +193,20 @@ void nfs_local_probe(struct nfs_client *clp)
 }
 EXPORT_SYMBOL_GPL(nfs_local_probe);
 
+void nfs_local_probe_async_work(struct work_struct *work)
+{
+	struct nfs_client *clp =
+		container_of(work, struct nfs_client, cl_local_probe_work);
+
+	nfs_local_probe(clp);
+}
+
+void nfs_local_probe_async(struct nfs_client *clp)
+{
+	queue_work(nfsiod_workqueue, &clp->cl_local_probe_work);
+}
+EXPORT_SYMBOL_GPL(nfs_local_probe_async);
+
 static inline struct nfsd_file *nfs_local_file_get(struct nfsd_file *nf)
 {
 	return nfs_to->nfsd_file_get(nf);

fs/nfs/nfs4state.c

@@ -1955,6 +1955,7 @@ static int nfs4_do_reclaim(struct nfs_client *clp, const struct nfs4_state_recov
 	}
 	rcu_read_unlock();
 	nfs4_free_state_owners(&freeme);
+	nfs_local_probe_async(clp);
 	if (lost_locks)
 		pr_warn("NFS: %s: lost %d locks\n",
 			clp->cl_hostname, lost_locks);

include/linux/nfs_fs_sb.h

@@ -131,6 +131,7 @@ struct nfs_client {
 	struct timespec64	cl_nfssvc_boot;
 	seqlock_t		cl_boot_lock;
 	nfs_uuid_t		cl_uuid;
+	struct work_struct	cl_local_probe_work;
 #endif /* CONFIG_NFS_LOCALIO */
 };