syscalls: fix more deadlocks and issues

kernel-src/sys/syscalls/chdir.c

@@ -33,6 +33,8 @@ syscallret_t syscall_chdir(context_t *, char *upath) {
 	if (ret.errno)
 		goto cleanup;
 
+	VOP_UNLOCK(new);
+
 	if (new->type != V_TYPE_DIR) {
 		ret.errno = ENOTDIR;
 		goto cleanup;

kernel-src/sys/syscalls/mount.c

@@ -78,8 +78,11 @@ syscallret_t syscall_mount(context_t *context, char *ubacking, char *umountpoint
 		ret.errno = vfs_lookup(&backingnode, backingrefnode, backing, NULL, 0);
 		if (ret.errno)
 			goto cleanup;
+
+		VOP_UNLOCK(backingnode);
 	}
 
+
 	ret.errno = vfs_mount(backingnode, mountpointrefnode, mountpoint, fs, data);
 	if (ubacking) {
 		VOP_RELEASE(backingnode);

kernel-src/sys/syscalls/renameat.c

@@ -60,7 +60,7 @@ syscallret_t syscall_renameat(context_t *context, int olddirfd, char *uoldpath,
 	if (oldcomponent == NULL && newcomponent == NULL)
 		goto cleanup;
 
-	// TODO possibly deadlocks
+	// TODO deadlocks.
 	ret.errno = vfs_lookup(&sourcedirnode, olddirnode, oldpath, oldcomponent, VFS_LOOKUP_NOLINK | VFS_LOOKUP_PARENT);
 	if (ret.errno)
 		goto cleanup;