NFS: Fix an Oops in nfs_setattr()

It looks like nfs_setattr() and nfs_rename() also need to test whether the
target is a regular file before calling nfs_wb_all()...
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fs/nfs/dir.c

@@ -1684,7 +1684,8 @@ static int nfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 	 * ... prune child dentries and writebacks if needed.
 	 */
 	if (atomic_read(&old_dentry->d_count) > 1) {
-		nfs_wb_all(old_inode);
+		if (S_ISREG(old_inode->i_mode))
+			nfs_wb_all(old_inode);
 		shrink_dcache_parent(old_dentry);
 	}
 	nfs_inode_return_delegation(old_inode);

fs/nfs/inode.c

@@ -341,8 +341,10 @@ nfs_setattr(struct dentry *dentry, struct iattr *attr)
 	lock_kernel();
 	nfs_begin_data_update(inode);
 	/* Write all dirty data */
-	filemap_write_and_wait(inode->i_mapping);
-	nfs_wb_all(inode);
+	if (S_ISREG(inode->i_mode)) {
+		filemap_write_and_wait(inode->i_mapping);
+		nfs_wb_all(inode);
+	}
 	/*
 	 * Return any delegations if we're going to change ACLs
 	 */