DAOS-16563 client: mark pool/cont handle as g2l after fork (#15125)

This patch marks all pool and container handles as if they
were created with g2l in the child processes after fork.
It prevents misinteractions if one of the child processes
closes the handle.
The marking is done by iterating through all the pool and
container handles which was not supported by the hhash code.

This patch also:
- adds support for fork to pydaos.
- introduces daos_reinit() to be called after fork.
- fixes IL to set the atfork callback when no extra eq are used.
- remove support for creating an event queue for each pydaos
  put/get operation. This makes the global event queue the only
  option. This should probably be moved to a per-thread eq in
  the future.

Signed-off-by: Johann Lombardi <johann.lombardi@gmail.com>

src/client/api/init.c

@@ -361,3 +361,32 @@ daos_fini(void)
 	D_MUTEX_UNLOCK(&module_lock);
 	return rc;
 }
+
+/**
+ * Re-initialize the DAOS library in the child process after fork.
+ */
+int
+daos_reinit(void)
+{
+	int rc;
+
+	rc = daos_eq_lib_reset_after_fork();
+	if (rc)
+		return rc;
+
+	daos_dti_reset();
+
+	/**
+	 * Mark all pool and container handles owned by the parent process as if they were created
+	 * in the child processes with g2l to avoid confusing the DAOS engines.
+	 */
+	rc = dc_pool_mark_all_slave();
+	if (rc)
+		return rc;
+
+	rc = dc_cont_mark_all_slave();
+	if (rc)
+		return rc;
+
+	return 0;
+}

src/client/dfuse/il/int_posix.c

@@ -818,16 +818,20 @@ child_hdlr(void)
 {
 	int rc;
 
-	rc = daos_eq_lib_reset_after_fork();
+	rc = daos_reinit();
 	if (rc)
-		DL_WARN(rc, "daos_eq_lib_init() failed in child process");
-	daos_dti_reset();
+		DL_WARN(rc, "daos_reinit() failed in child process");
+
+	/** Reset event queue */
 	ioil_eqh = ioil_iog.iog_main_eqh = DAOS_HDL_INVAL;
-	rc = daos_eq_create(&ioil_eqh);
-	if (rc)
-		DFUSE_LOG_WARNING("daos_eq_create() failed: "DF_RC, DP_RC(rc));
-	else
-		ioil_iog.iog_main_eqh = ioil_eqh;
+
+	if (ioil_iog.iog_eq_count_max) {
+		rc = daos_eq_create(&ioil_eqh);
+		if (rc)
+			DFUSE_LOG_WARNING("daos_eq_create() failed: " DF_RC, DP_RC(rc));
+		else
+			ioil_iog.iog_main_eqh = ioil_eqh;
+	}
 }
 
 /* Returns true on success */
@@ -876,10 +880,12 @@ check_ioctl_on_open(int fd, struct fd_entry *entry, int flags)
 				D_GOTO(err, rc = daos_der2errno(rc));
 			}
 			ioil_iog.iog_main_eqh = ioil_eqh;
-
-			rc = pthread_atfork(NULL, NULL, &child_hdlr);
-			D_ASSERT(rc == 0);
 		}
+
+		rc = pthread_atfork(NULL, NULL, &child_hdlr);
+		if (rc)
+			DFUSE_LOG_WARNING("Failed to install atfork handler: " DF_RC, DP_RC(rc));
+		rc = 0;
 	}
 
 	d_list_for_each_entry(pool, &ioil_iog.iog_pools_head, iop_pools) {

src/client/dfuse/pil4dfs/int_dfs.c

@@ -939,10 +939,9 @@ child_hdlr(void)
 	if (atomic_load_relaxed(&d_daos_inited) == false)
 		return;
 
-	rc = daos_eq_lib_reset_after_fork();
+	rc = daos_reinit();
 	if (rc)
-		DL_WARN(rc, "daos_eq_lib_init() failed in child process");
-	daos_dti_reset();
+		DL_WARN(rc, "daos_reinit() failed in child process");
 	td_eqh = main_eqh = DAOS_HDL_INVAL;
 	context_reset = true;
 }

src/client/pydaos/pydaos_shim.c

@@ -63,30 +63,48 @@ struct open_handle {
 		}                                                                                  \
 	} while (0)
 
-static daos_handle_t glob_eq;
-static bool          use_glob_eq;
+/** Global event queue */
+static daos_handle_t eq;
 
 /**
  * Implementations of baseline shim functions
  */
 
+static void
+child_handler(void)
+{
+	int rc;
+
+	rc = daos_reinit();
+	if (rc)
+		D_WARN("daos_reinit() failed in child process %d", rc);
+
+	eq = DAOS_HDL_INVAL;
+	rc = daos_eq_create(&eq);
+	if (rc)
+		DL_ERROR(rc, "Failed to re-create global eq");
+}
+
 static PyObject *
 __shim_handle__daos_init(PyObject *self, PyObject *args)
 {
 	int rc;
 
 	rc = daos_init();
-	if ((rc == 0) && (use_glob_eq == 0)) {
-		d_getenv_bool("PYDAOS_GLOB_EQ", &use_glob_eq);
-		if (use_glob_eq) {
-			int ret;
-
-			ret = daos_eq_create(&glob_eq);
-			if (ret) {
-				DL_ERROR(ret, "Failed to create global eq");
-				use_glob_eq = false;
-			}
-		}
+	if (rc)
+		return PyLong_FromLong(rc);
+
+	rc = daos_eq_create(&eq);
+	if (rc) {
+		DL_ERROR(rc, "Failed to create global eq");
+		daos_fini();
+		return PyLong_FromLong(rc);
+	}
+
+	rc = pthread_atfork(NULL, NULL, &child_handler);
+	if (rc) {
+		DL_ERROR(rc, "Failed to set atfork handler");
+		return PyLong_FromLong(rc);
 	}
 
 	return PyLong_FromLong(rc);
@@ -97,12 +115,9 @@ __shim_handle__daos_fini(PyObject *self, PyObject *args)
 {
 	int rc;
 
-	if (use_glob_eq) {
-		rc =  daos_eq_destroy(glob_eq, DAOS_EQ_DESTROY_FORCE);
-		if (rc)
-			D_ERROR("Failed to destroy global eq, "DF_RC"\n", DP_RC(rc));
-		use_glob_eq = false;
-	}
+	rc = daos_eq_destroy(eq, DAOS_EQ_DESTROY_FORCE);
+	if (rc)
+		D_ERROR("Failed to destroy global eq, " DF_RC "\n", DP_RC(rc));
 
 	rc = daos_fini();
 
@@ -914,8 +929,7 @@ __shim_handle__kv_get(PyObject *self, PyObject *args)
 	PyObject	*daos_dict;
 	daos_handle_t	 oh;
 	PyObject	*key;
-	Py_ssize_t	 pos = 0;
-	daos_handle_t	 eq;
+	Py_ssize_t       pos      = 0;
 	struct kv_op	*kv_array = NULL;
 	struct kv_op	*op;
 	daos_event_t	*evp;
@@ -928,14 +942,6 @@ __shim_handle__kv_get(PyObject *self, PyObject *args)
 	RETURN_NULL_IF_FAILED_TO_PARSE(args, "LO!l", &oh.cookie, &PyDict_Type,
 				       &daos_dict, &v_size);
 
-	if (!use_glob_eq) {
-		rc = daos_eq_create(&eq);
-		if (rc)
-			return PyLong_FromLong(rc);
-	} else {
-		eq = glob_eq;
-	}
-
 	D_ALLOC_ARRAY(kv_array, MAX_INFLIGHT);
 	if (kv_array == NULL) {
 		rc = -DER_NOMEM;
@@ -1079,19 +1085,10 @@ __shim_handle__kv_get(PyObject *self, PyObject *args)
 out:
 	D_FREE(kv_array);
 
-	/** destroy event queue */
-	if (!use_glob_eq) {
-		ret = daos_eq_destroy(eq, DAOS_EQ_DESTROY_FORCE);
-		if (rc == DER_SUCCESS && ret < 0)
-			rc = ret;
-	}
-
 	/* Populate return list */
 	return PyLong_FromLong(rc);
 
 err:
-	if (!use_glob_eq)
-		daos_eq_destroy(eq, DAOS_EQ_DESTROY_FORCE);
 	D_FREE(kv_array);
 
 	return NULL;
@@ -1104,8 +1101,7 @@ __shim_handle__kv_put(PyObject *self, PyObject *args)
 	daos_handle_t	 oh;
 	PyObject	*key;
 	PyObject	*value;
-	Py_ssize_t	 pos = 0;
-	daos_handle_t	 eq;
+	Py_ssize_t       pos = 0;
 	daos_event_t	 ev_array[MAX_INFLIGHT];
 	daos_event_t	*evp;
 	int		 i = 0;
@@ -1116,14 +1112,6 @@ __shim_handle__kv_put(PyObject *self, PyObject *args)
 	RETURN_NULL_IF_FAILED_TO_PARSE(args, "LO!", &oh.cookie,
 				       &PyDict_Type, &daos_dict);
 
-	if (!use_glob_eq) {
-		rc = daos_eq_create(&eq);
-		if (rc)
-			return PyLong_FromLong(rc);
-	} else {
-		eq = glob_eq;
-	}
-
 	while (PyDict_Next(daos_dict, &pos, &key, &value)) {
 		char		*buf;
 		daos_size_t	 size;
@@ -1203,17 +1191,8 @@ __shim_handle__kv_put(PyObject *self, PyObject *args)
 	if (rc == DER_SUCCESS && ret < 0)
 		rc = ret;
 
-	/** destroy event queue */
-	if (!use_glob_eq) {
-		ret = daos_eq_destroy(eq, 0);
-		if (rc == DER_SUCCESS && ret < 0)
-			rc = ret;
-	}
-
 	return PyLong_FromLong(rc);
 err:
-	if (!use_glob_eq)
-		daos_eq_destroy(eq, 0);
 	return NULL;
 }
 

src/common/misc.c

@@ -630,6 +630,12 @@ daos_hhash_link_delete(struct d_hlink *hlink)
 	return d_hhash_link_delete(daos_ht.dht_hhash, hlink);
 }
 
+int
+daos_hhash_traverse(int type, daos_hhash_traverse_cb_t cb, void *arg)
+{
+	return d_hhash_traverse(daos_ht.dht_hhash, type, cb, arg);
+}
+
 /**
  * a helper to get the needed crt_init_opt.
  *

src/container/cli.c

@@ -3524,3 +3524,20 @@ dc_cont_hdl2props(daos_handle_t coh)
 
 	return result;
 }
+
+static int
+cont_mark_slave(struct d_hlink *link, void *arg)
+{
+	struct dc_cont *cont;
+
+	cont           = container_of(link, struct dc_cont, dc_hlink);
+	cont->dc_slave = 1;
+
+	return 0;
+}
+
+int
+dc_cont_mark_all_slave(void)
+{
+	return daos_hhash_traverse(DAOS_HTYPE_CO, cont_mark_slave, NULL);
+}

src/gurt/hash.c

@@ -1344,6 +1344,42 @@ d_hhash_key_type(uint64_t key)
 	return d_hhash_key_isptr(key) ? D_HTYPE_PTR : key & D_HTYPE_MASK;
 }
 
+struct traverse_args {
+	int                   type;
+	d_hhash_traverse_cb_t cb;
+	void                 *arg;
+};
+
+static int
+d_hhash_cb(d_list_t *link, void *args)
+{
+	struct traverse_args *targs = args;
+	struct d_hlink       *hlink = link2hlink(link);
+	uint64_t              key;
+
+	if (hlink == NULL)
+		return 0;
+
+	d_hhash_link_key(hlink, &key);
+
+	if (targs->type != d_hhash_key_type(key))
+		return 0;
+
+	return targs->cb(hlink, targs->arg);
+}
+
+int
+d_hhash_traverse(struct d_hhash *hhash, int type, d_hhash_traverse_cb_t cb, void *arg)
+{
+	struct traverse_args args;
+
+	args.type = type;
+	args.cb   = cb;
+	args.arg  = arg;
+
+	return d_hash_table_traverse(&hhash->ch_htable, d_hhash_cb, &args);
+}
+
 /******************************************************************************
  * UUID Hash Table Wrapper
  * Key: UUID

src/include/daos.h

@@ -46,6 +46,17 @@ daos_init(void);
 int
 daos_fini(void);
 
+/**
+ * Reinitialize DAOS library after a fork call.
+ * For applications that initialize DAOS and then call fork without exec, some
+ * internal data structures must be reinitialized in the child process.
+ * It is recommended to call this function from a fork handler registered via
+ * pthread_atfork(). If any event queues were created prior to the fork call,
+ * those must be re-created in the child process.
+ */
+int
+daos_reinit(void);
+
 #if defined(__cplusplus)
 }
 #endif

src/include/daos/common.h

@@ -959,6 +959,10 @@ bool daos_hhash_link_delete(struct d_hlink *hlink);
 #define daos_hhash_link_empty(hlink)		d_hhash_link_empty(hlink)
 #define daos_hhash_link_key(hlink, key)		d_hhash_link_key(hlink, key)
 
+typedef int (*daos_hhash_traverse_cb_t)(struct d_hlink *link, void *arg);
+int
+daos_hhash_traverse(int type, daos_hhash_traverse_cb_t cb, void *arg);
+
 /* daos_recx_t overlap detector */
 #define DAOS_RECX_OVERLAP(recx_1, recx_2)				\
 	(((recx_1).rx_idx < (recx_2).rx_idx + (recx_2).rx_nr) &&	\

src/include/daos/container.h

@@ -149,4 +149,6 @@ dc_cont_open_flags_valid(uint64_t flags)
 	return true;
 }
 
+int
+dc_cont_mark_all_slave(void);
 #endif /* __DD_CONT_H__ */

src/include/daos/pool.h

@@ -198,4 +198,7 @@ int dc_pool_create_map_refresh_task(daos_handle_t pool_hdl, uint32_t map_version
 				    tse_sched_t *sched, tse_task_t **task);
 void dc_pool_abandon_map_refresh_task(tse_task_t *task);
 
+int
+dc_pool_mark_all_slave(void);
+
 #endif /* __DD_POOL_H__ */

src/include/gurt/hash.h

@@ -580,6 +580,9 @@ int  d_hhash_key_type(uint64_t key);
 bool d_hhash_key_isptr(uint64_t key);
 int  d_hhash_set_ptrtype(struct d_hhash *hhash);
 bool d_hhash_is_ptrtype(struct d_hhash *hhash);
+typedef int (*d_hhash_traverse_cb_t)(struct d_hlink *link, void *arg);
+int
+d_hhash_traverse(struct d_hhash *hhash, int type, d_hhash_traverse_cb_t cb, void *arg);
 
 /******************************************************************************
  * UUID Hash Table Wrapper