handle fetch retries on pool count changes

Signed-off-by: Michael MacDonald <mjmac@google.com>

src/control/cmd/daos/pool.go

@@ -599,34 +599,48 @@ func (cmd *poolAutoTestCmd) Execute(_ []string) error {
 }
 
 func getPoolList(log logging.Logger, sysName string, queryEnabled bool) ([]*daos.PoolInfo, error) {
- var rc C.int
- bufSize := C.size_t(0)
-
- // First, fetch the total number of pools in the system.
- // We may not have access to all of them, so this is an upper bound.
- rc = C.daos_mgmt_list_pools(nil, &bufSize, nil, nil)
- if err := daosError(rc); err != nil {
- return nil, err
- }
-
- if bufSize < 1 {
- return nil, nil
- }
-
  var cSysName *C.char
  if sysName != "" {
  cSysName := C.CString(sysName)
  defer freeString(cSysName)
  }
 
- // Now, we actually fetch the pools into the buffer that we've created.
- cPools := make([]C.daos_mgmt_pool_info_t, bufSize)
- rc = C.daos_mgmt_list_pools(nil, &bufSize, &cPools[0], nil)
- if err := daosError(rc); err != nil {
+ var cPools []C.daos_mgmt_pool_info_t
+ for {
+ var rc C.int
+ var poolCount C.size_t
+
+ // First, fetch the total number of pools in the system.
+ // We may not have access to all of them, so this is an upper bound.
+ rc = C.daos_mgmt_list_pools(cSysName, &poolCount, nil, nil)
+ if err := daosError(rc); err != nil {
+ return nil, err
+ }
+ log.Debugf("pools in system: %d", poolCount)
+
+ if poolCount < 1 {
+ return nil, nil
+ }
+
+ // Now, we actually fetch the pools into the buffer that we've created.
+ cPools = make([]C.daos_mgmt_pool_info_t, poolCount)
+ rc = C.daos_mgmt_list_pools(cSysName, &poolCount, &cPools[0], nil)
+ err := daosError(rc)
+ if err == nil {
+ cPools = cPools[:poolCount] // adjust the slice to the number of pools retrieved
+ log.Debugf("fetched %d pools", len(cPools))
+ break
+ }
+ if err == daos.StructTooSmall {
+ log.Notice("server-side pool list changed; re-fetching")
+ continue
+ }
+ log.Errorf("failed to fetch pool list: %s", err)
  return nil, err
  }
- pools := make([]*daos.PoolInfo, 0, bufSize)
- for i := 0; i < int(bufSize); i++ {
+
+ pools := make([]*daos.PoolInfo, 0, len(cPools))
+ for i := 0; i < len(cPools); i++ {
  cPool := &cPools[i]
 
  svcRanks, err := rankSetFromC(cPool.mgpi_svc)

src/engine/drpc_client.c

@@ -1,5 +1,5 @@
 /*
- * (C) Copyright 2019-2021 Intel Corporation.
+ * (C) Copyright 2019-2024 Intel Corporation.
  *
  * SPDX-License-Identifier: BSD-2-Clause-Patent
  */
@@ -459,7 +459,7 @@ ds_get_pool_list(uint64_t *npools, daos_mgmt_pool_info_t *pools)
  if (*npools > 0 && lp_resp->n_pools > *npools) {
  D_ERROR("pool list exceeds request buffer (req: %lu, actual: %lu)", *npools,
  lp_resp->n_pools);
- D_GOTO(out_resp, rc = -DER_TRUNC);
+ D_GOTO(out_resp, rc = -DER_OVERFLOW);
  }
 
  *npools = lp_resp->n_pools;

src/mgmt/cli_mgmt.c

@@ -1374,10 +1374,8 @@ dc_mgmt_pool_list(tse_task_t *task)
  }
 
  rc = out->plo_op.mo_rc;
- if (rc != 0) {
- DL_ERROR(rc, "failed to list pools");
+ if (rc != 0)
  D_GOTO(out_put_req, rc);
- }
 
  *args->npools = out->plo_npools;
 

src/mgmt/srv.c

@@ -530,6 +530,15 @@ ds_mgmt_pool_list_hdlr(crt_rpc_t *rpc)
 send_resp:
  out->plo_op.mo_rc = rc;
 
+ if (rc == 0) {
+ if (n_rpc > 0)
+ D_DEBUG(DB_MGMT, "returning %zu/%zu pools\n", n_rpc, n_mgmt);
+ else
+ D_DEBUG(DB_MGMT, "returning %zu pools\n", n_mgmt);
+ } else {
+ DL_ERROR(rc, "failed to list pools");
+ }
+
  rc = crt_reply_send(rpc);
  if (rc != 0)
  DL_ERROR(rc, "crt_reply_send() failed");