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

1 files changed, 9 insertions, 4 deletions

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index b8323aa7b543..bbc49caa7a82 100644
--- a/fs/nfs/pnfs.c
+++ b/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;