DAOS-17321 ddb: Add checksum dump function to ddb VOS API

src/utils/ddb/ddb_vos.c

@@ -1093,6 +1093,117 @@ dv_dump_value(daos_handle_t poh, struct dv_tree_path *path, dv_dump_value_cb dum
 	return rc;
 }
 
+static int
+dump_csum_sv(daos_handle_t coh, daos_key_t *dkey, daos_unit_oid_t *oid, daos_iod_t *iod,
+	     daos_epoch_t epoch, dv_dump_csum_cb dump_cb, void *cb_arg)
+{
+	daos_handle_t       ioh;
+	struct dcs_ci_list *cil;
+	int                 cb_rc = 0;
+	int                 rc;
+
+	rc = vos_fetch_begin(coh, *oid, epoch, dkey, 1, iod, VOS_OF_FETCH_CSUM, NULL, &ioh, NULL);
+	if (!SUCCESS(rc)) {
+		D_ERROR("vos_fetch_begin for csum dump of " DF_UOID " failed: " DF_RC "\n",
+			DP_UOID(*oid), DP_RC(rc));
+		goto out;
+	}
+
+	cil = vos_ioh2ci(ioh);
+
+	cb_rc = dump_cb(cb_arg, NULL, cil);
+	if (!SUCCESS(cb_rc))
+		D_DEBUG(DB_IO, "Csum dump callback for " DF_UOID " returned: " DF_RC "\n",
+			DP_UOID(*oid), DP_RC(cb_rc));
+
+	rc = vos_fetch_end(ioh, NULL, cb_rc);
+	if (!SUCCESS(rc) && rc != cb_rc)
+		D_ERROR("vos_fetch_end for csum dump of " DF_UOID " failed: " DF_RC "\n",
+			DP_UOID(*oid), DP_RC(rc));
+
+out:
+	if (!SUCCESS(cb_rc))
+		rc = cb_rc;
+	return rc;
+}
+
+static int
+dump_csum_recx(daos_handle_t coh, daos_key_t *dkey, daos_unit_oid_t *oid, daos_iod_t *iod,
+	       daos_epoch_t epoch, dv_dump_csum_cb dump_cb, void *cb_arg)
+{
+	daos_handle_t             ioh;
+	struct dcs_ci_list       *cil;
+	struct daos_recx_ep_list *rel;
+	int                       cb_rc = 0;
+	int                       rc;
+
+	rc = vos_fetch_begin(coh, *oid, epoch, dkey, 1, iod, VOS_OF_FETCH_CSUM, NULL, &ioh, NULL);
+	if (!SUCCESS(rc)) {
+		D_ERROR("vos_fetch_begin for csum dump of " DF_UOID " failed: " DF_RC "\n",
+			DP_UOID(*oid), DP_RC(rc));
+		goto out;
+	}
+
+	cil = vos_ioh2ci(ioh);
+	rel = vos_ioh2recx_list(ioh);
+
+	cb_rc = dump_cb(cb_arg, rel, cil);
+	if (!SUCCESS(cb_rc))
+		D_DEBUG(DB_IO, "Csum dump callback for " DF_UOID " returned: " DF_RC "\n",
+			DP_UOID(*oid), DP_RC(cb_rc));
+
+	/* rel ownership is transferred by vos_ioh2recx_list(); free before vos_fetch_end. */
+	daos_recx_ep_list_free(rel, iod->iod_nr);
+	rc = vos_fetch_end(ioh, NULL, cb_rc);
+	if (!SUCCESS(rc) && rc != cb_rc)
+		D_ERROR("vos_fetch_end for csum dump of " DF_UOID " failed: " DF_RC "\n",
+			DP_UOID(*oid), DP_RC(rc));
+
+out:
+	if (!SUCCESS(cb_rc))
+		rc = cb_rc;
+	return rc;
+}
+
+int
+dv_dump_csum(daos_handle_t poh, struct dv_tree_path *path, daos_epoch_t epoch,
+	     dv_dump_csum_cb dump_cb, void *cb_arg)
+{
+	daos_handle_t coh;
+	daos_iod_t    iod = {0};
+	int           rc  = 0;
+
+	/* No-op when no callback is provided; the caller controls whether to consume results. */
+	if (dump_cb == NULL)
+		goto out;
+
+	rc = vos_cont_open(poh, path->vtp_cont, &coh);
+	if (!SUCCESS(rc)) {
+		D_ERROR("Opening container for csum dump of " DF_UOID " failed: " DF_RC "\n",
+			DP_UOID(path->vtp_oid), DP_RC(rc));
+		goto out;
+	}
+
+	iod.iod_name  = path->vtp_akey;
+	iod.iod_recxs = &path->vtp_recx;
+	iod.iod_nr    = 1;
+	iod.iod_size  = 0;
+	if (path->vtp_is_recx) {
+		iod.iod_type = DAOS_IOD_ARRAY;
+		rc = dump_csum_recx(coh, &path->vtp_dkey, &path->vtp_oid, &iod, epoch, dump_cb,
+				    cb_arg);
+	} else {
+		iod.iod_type = DAOS_IOD_SINGLE;
+		rc = dump_csum_sv(coh, &path->vtp_dkey, &path->vtp_oid, &iod, epoch, dump_cb,
+				  cb_arg);
+	}
+
+	vos_cont_close(coh);
+
+out:
+	return rc;
+}
+
 static void
 ilog_entry_status(enum ilog_status status, char *status_str, uint32_t status_str_len)
 {

src/utils/ddb/ddb_vos.h

@@ -155,6 +155,37 @@ typedef int (*dv_dump_value_cb)(void *cb_arg, d_iov_t *value);
 int dv_dump_value(daos_handle_t poh, struct dv_tree_path *path, dv_dump_value_cb dump_cb,
 		  void *cb_arg);
 
+/**
+ * Callback invoked by dv_dump_csum() with the fetched checksum information.
+ *
+ * @param cb_arg  User-provided argument passed through from dv_dump_csum().
+ * @param rel     Recx/epoch list describing the stored extents. NULL for single-value akeys;
+ *                non-NULL for array akeys. The caller must not free this pointer.
+ * @param cil     Checksum info list. Valid only for the duration of the callback.
+ * @return        0 on success; a negative error code is propagated back to the caller of
+ *                dv_dump_csum().
+ */
+typedef int (*dv_dump_csum_cb)(void *cb_arg, struct daos_recx_ep_list *rel,
+			       struct dcs_ci_list *cil);
+
+/**
+ * Fetch and dump the checksum information for the akey identified by \a path.
+ *
+ * @param poh      Open pool handle.
+ * @param path     VOS tree path identifying the container, object, dkey, and akey.
+ *                 For array akeys, path->vtp_recx selects the extent to inspect.
+ * @param epoch    Epoch for the fetch. For single-value akeys, controls which version is
+ *                 returned — pass DAOS_EPOCH_MAX to get the latest, or a snapshot epoch to
+ *                 access an earlier version. For array akeys, selects the visible extent set.
+ * @param dump_cb  Callback invoked with the result. If NULL, the function returns 0
+ *                 without opening the container or calling VOS.
+ * @param cb_arg   Opaque argument forwarded to \a dump_cb.
+ * @return         0 on success, or a negative error code.
+ */
+int
+dv_dump_csum(daos_handle_t poh, struct dv_tree_path *path, daos_epoch_t epoch,
+	     dv_dump_csum_cb dump_cb, void *cb_arg);
+
 struct ddb_ilog_entry {
 	uint32_t	die_idx;
 	int32_t		die_status;