pNFS: return status from nfs4_pnfs_ds_connect

The nfs4_pnfs_ds_connect path can call rpc_create which can fail or it
can wait on another context to reach the same failure.

This checks that the rpc_create succeeded and returns the error to the
caller.

When an error is returned, both the files and flexfiles layouts will return
NULL from _prepare_ds(). The flexfiles layout will also return the layout
with the error NFS4ERR_NXIO.

Signed-off-by: Weston Andros Adamson <[e-mail]>
Signed-off-by: Anna Schumaker <[e-mail]>

fs/nfs/client.c

···
 	return NULL;
 }
 
-static bool nfs_client_init_is_complete(const struct nfs_client *clp)
+/*
+ * Return true if @clp is done initializing, false if still working on it.
+ *
+ * Use nfs_client_init_status to check if it was successful.
+ */
+bool nfs_client_init_is_complete(const struct nfs_client *clp)
 {
 	return clp->cl_cons_state <= NFS_CS_READY;
 }
+EXPORT_SYMBOL_GPL(nfs_client_init_is_complete);
+
+/*
+ * Return 0 if @clp was successfully initialized, -errno otherwise.
+ *
+ * This must be called *after* nfs_client_init_is_complete() returns true,
+ * otherwise it will pop WARN_ON_ONCE and return -EINVAL
+ */
+int nfs_client_init_status(const struct nfs_client *clp)
+{
+	/* called without checking nfs_client_init_is_complete */
+	if (clp->cl_cons_state > NFS_CS_READY) {
+		WARN_ON_ONCE(1);
+		return -EINVAL;
+	}
+	return clp->cl_cons_state;
+}
+EXPORT_SYMBOL_GPL(nfs_client_init_status);
 
 int nfs_wait_client_init_complete(const struct nfs_client *clp)
 {

fs/nfs/filelayout/filelayoutdev.c

···
 	struct nfs4_deviceid_node *devid = FILELAYOUT_DEVID_NODE(lseg);
 	struct nfs4_pnfs_ds *ret = ds;
 	struct nfs_server *s = NFS_SERVER(lseg->pls_layout->plh_inode);
+	int status;
 
 	if (ds == NULL) {
 		printk(KERN_ERR "NFS: %s: No data server for offset index %d\n",
···
 	if (ds->ds_clp)
 		goto out_test_devid;
 
-	nfs4_pnfs_ds_connect(s, ds, devid, dataserver_timeo,
+	status = nfs4_pnfs_ds_connect(s, ds, devid, dataserver_timeo,
 			     dataserver_retrans, 4,
 			     s->nfs_client->cl_minorversion);
+	if (status) {
+		ret = NULL;
+		goto out;
+	}
 
 out_test_devid:
 	if (ret->ds_clp == NULL ||

fs/nfs/flexfilelayout/flexfilelayoutdev.c

···
 	struct inode *ino = lseg->pls_layout->plh_inode;
 	struct nfs_server *s = NFS_SERVER(ino);
 	unsigned int max_payload;
+	int status;
 
 	if (!ff_layout_mirror_valid(lseg, mirror, true)) {
 		pr_err_ratelimited("NFS: %s: No data server for offset index %d\n",
···
 	/* FIXME: For now we assume the server sent only one version of NFS
 	 * to use for the DS.
 	 */
-	nfs4_pnfs_ds_connect(s, ds, devid, dataserver_timeo,
+	status = nfs4_pnfs_ds_connect(s, ds, devid, dataserver_timeo,
 			     dataserver_retrans,
 			     mirror->mirror_ds->ds_versions[0].version,
 			     mirror->mirror_ds->ds_versions[0].minor_version);

fs/nfs/internal.h

···
 					   struct nfs_fh *,
 					   struct nfs_fattr *,
 					   rpc_authflavor_t);
+extern bool nfs_client_init_is_complete(const struct nfs_client *clp);
+extern int nfs_client_init_status(const struct nfs_client *clp);
 extern int nfs_wait_client_init_complete(const struct nfs_client *clp);
 extern void nfs_mark_client_ready(struct nfs_client *clp, int state);
 extern struct nfs_client *nfs4_set_ds_client(struct nfs_server *mds_srv,

fs/nfs/pnfs.h

···
 struct nfs4_pnfs_ds *nfs4_pnfs_ds_add(struct list_head *dsaddrs,
 				      gfp_t gfp_flags);
 void nfs4_pnfs_v3_ds_connect_unload(void);
-void nfs4_pnfs_ds_connect(struct nfs_server *mds_srv, struct nfs4_pnfs_ds *ds,
+int nfs4_pnfs_ds_connect(struct nfs_server *mds_srv, struct nfs4_pnfs_ds *ds,
 			  struct nfs4_deviceid_node *devid, unsigned int timeo,
 			  unsigned int retrans, u32 version, u32 minor_version);
 struct nfs4_pnfs_ds_addr *nfs4_decode_mp_ds_addr(struct net *net,

fs/nfs/pnfs_nfs.c

···
 /*
  * Create an rpc connection to the nfs4_pnfs_ds data server.
  * Currently only supports IPv4 and IPv6 addresses.
- * If connection fails, make devid unavailable.
+ * If connection fails, make devid unavailable and return a -errno.
  */
-void nfs4_pnfs_ds_connect(struct nfs_server *mds_srv, struct nfs4_pnfs_ds *ds,
+int nfs4_pnfs_ds_connect(struct nfs_server *mds_srv, struct nfs4_pnfs_ds *ds,
 			  struct nfs4_deviceid_node *devid, unsigned int timeo,
 			  unsigned int retrans, u32 version, u32 minor_version)
 {
···
 	} else {
 		nfs4_wait_ds_connect(ds);
 	}
+
+	/*
+	 * At this point the ds->ds_clp should be ready, but it might have
+	 * hit an error.
+	 */
+	if (!ds->ds_clp || !nfs_client_init_is_complete(ds->ds_clp)) {
+		WARN_ON_ONCE(1);
+		return -EINVAL;
+	}
+
+	return nfs_client_init_status(ds->ds_clp);
 }
 EXPORT_SYMBOL_GPL(nfs4_pnfs_ds_connect);