NFS client bugfixes for Linux 3.5

Fixes include:
 - Fix a write hang due to an uninitalised variable when !defined(CONFIG_NFS_V4)
 - Address upcall races in the legacy NFSv4 idmapper
 - Remove an O_DIRECT refcounting issue
 - Fix a pNFS refcounting bug when the file layout metadata server is also
   acting as a data server
 - Fix a pNFS module loading race.
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Merge tag 'nfs-for-3.5-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Pull NFS client bugfixes from Trond Myklebust:
 - Fix a write hang due to an uninitalised variable when
   !defined(CONFIG_NFS_V4)
 - Address upcall races in the legacy NFSv4 idmapper
 - Remove an O_DIRECT refcounting issue
 - Fix a pNFS refcounting bug when the file layout metadata server is
   also acting as a data server
 - Fix a pNFS module loading race.

* tag 'nfs-for-3.5-3' of git://git.linux-nfs.org/projects/trondmy/linux-nfs:
  NFS: Force the legacy idmapper to be single threaded
  NFS: Initialise commit_info.rpc_out when !defined(CONFIG_NFS_V4)
  NFS: Fix a refcounting issue in O_DIRECT
  NFSv4.1: Fix a race in set_pnfs_layoutdriver
  NFSv4.1: Fix umount when filelayout DS is also the MDS

fs/nfs/client.c

@@ -207,7 +207,6 @@ error_0:
 static void nfs4_shutdown_session(struct nfs_client *clp)
 {
 	if (nfs4_has_session(clp)) {
-		nfs4_deviceid_purge_client(clp);
 		nfs4_destroy_session(clp->cl_session);
 		nfs4_destroy_clientid(clp);
 	}

fs/nfs/direct.c

@@ -490,6 +490,7 @@ static void nfs_direct_write_reschedule(struct nfs_direct_req *dreq)
 			dreq->error = -EIO;
 			spin_unlock(cinfo.lock);
 		}
+		nfs_release_request(req);
 	}
 	nfs_pageio_complete(&desc);
 

fs/nfs/idmap.c

@@ -57,6 +57,11 @@ unsigned int nfs_idmap_cache_timeout = 600;
 static const struct cred *id_resolver_cache;
 static struct key_type key_type_id_resolver_legacy;
 
+struct idmap {
+	struct rpc_pipe		*idmap_pipe;
+	struct key_construction	*idmap_key_cons;
+	struct mutex		idmap_mutex;
+};
 
 /**
  * nfs_fattr_init_names - initialise the nfs_fattr owner_name/group_name fields
@@ -310,9 +315,11 @@ static ssize_t nfs_idmap_get_key(const char *name, size_t namelen,
 					    name, namelen, type, data,
 					    data_size, NULL);
 	if (ret < 0) {
+		mutex_lock(&idmap->idmap_mutex);
 		ret = nfs_idmap_request_key(&key_type_id_resolver_legacy,
 					    name, namelen, type, data,
 					    data_size, idmap);
+		mutex_unlock(&idmap->idmap_mutex);
 	}
 	return ret;
 }
@@ -354,11 +361,6 @@ static int nfs_idmap_lookup_id(const char *name, size_t namelen, const char *typ
 /* idmap classic begins here */
 module_param(nfs_idmap_cache_timeout, int, 0644);
 
-struct idmap {
-	struct rpc_pipe		*idmap_pipe;
-	struct key_construction	*idmap_key_cons;
-};
-
 enum {
 	Opt_find_uid, Opt_find_gid, Opt_find_user, Opt_find_group, Opt_find_err
 };
@@ -469,6 +471,7 @@ nfs_idmap_new(struct nfs_client *clp)
 		return error;
 	}
 	idmap->idmap_pipe = pipe;
+	mutex_init(&idmap->idmap_mutex);
 
 	clp->cl_idmap = idmap;
 	return 0;

fs/nfs/inode.c

@@ -1530,7 +1530,6 @@ static inline void nfs4_init_once(struct nfs_inode *nfsi)
 	nfsi->delegation_state = 0;
 	init_rwsem(&nfsi->rwsem);
 	nfsi->layout = NULL;
-	atomic_set(&nfsi->commit_info.rpcs_out, 0);
 #endif
 }
 
@@ -1545,6 +1544,7 @@ static void init_once(void *foo)
 	INIT_LIST_HEAD(&nfsi->commit_info.list);
 	nfsi->npages = 0;
 	nfsi->commit_info.ncommit = 0;
+	atomic_set(&nfsi->commit_info.rpcs_out, 0);
 	atomic_set(&nfsi->silly_count, 1);
 	INIT_HLIST_HEAD(&nfsi->silly_list);
 	init_waitqueue_head(&nfsi->waitqueue);

fs/nfs/pnfs.c

@@ -70,6 +70,10 @@ find_pnfs_driver(u32 id)
 
 	spin_lock(&pnfs_spinlock);
 	local = find_pnfs_driver_locked(id);
+	if (local != NULL && !try_module_get(local->owner)) {
+		dprintk("%s: Could not grab reference on module\n", __func__);
+		local = NULL;
+	}
 	spin_unlock(&pnfs_spinlock);
 	return local;
 }
@@ -80,6 +84,9 @@ unset_pnfs_layoutdriver(struct nfs_server *nfss)
 	if (nfss->pnfs_curr_ld) {
 		if (nfss->pnfs_curr_ld->clear_layoutdriver)
 			nfss->pnfs_curr_ld->clear_layoutdriver(nfss);
+		/* Decrement the MDS count. Purge the deviceid cache if zero */
+		if (atomic_dec_and_test(&nfss->nfs_client->cl_mds_count))
+			nfs4_deviceid_purge_client(nfss->nfs_client);
 		module_put(nfss->pnfs_curr_ld->owner);
 	}
 	nfss->pnfs_curr_ld = NULL;
@@ -115,10 +122,6 @@ set_pnfs_layoutdriver(struct nfs_server *server, const struct nfs_fh *mntfh,
 			goto out_no_driver;
 		}
 	}
-	if (!try_module_get(ld_type->owner)) {
-		dprintk("%s: Could not grab reference on module\n", __func__);
-		goto out_no_driver;
-	}
 	server->pnfs_curr_ld = ld_type;
 	if (ld_type->set_layoutdriver
 	    && ld_type->set_layoutdriver(server, mntfh)) {
@@ -127,6 +130,8 @@ set_pnfs_layoutdriver(struct nfs_server *server, const struct nfs_fh *mntfh,
 		module_put(ld_type->owner);
 		goto out_no_driver;
 	}
+	/* Bump the MDS count */
+	atomic_inc(&server->nfs_client->cl_mds_count);
 
 	dprintk("%s: pNFS module for %u set\n", __func__, id);
 	return;

include/linux/nfs_fs_sb.h

@@ -25,6 +25,7 @@ struct nfs41_impl_id;
  */
 struct nfs_client {
 	atomic_t		cl_count;
+	atomic_t		cl_mds_count;
 	int			cl_cons_state;	/* current construction state (-ve: init error) */
 #define NFS_CS_READY		0		/* ready to be used */
 #define NFS_CS_INITING		1		/* busy initialising */