Add a function users can use to cycle oids

Required-githooks: true

Signed-off-by: Jeff Olivier <jeffolivier@google.com>

src/client/dfs/dfs_internal.h

@@ -99,21 +99,6 @@
 /** Max recursion depth for symlinks */
 #define DFS_MAX_RECURSION  40
 
-/** MAX value for the HI OID */
-#define MAX_OID_HI         ((1UL << 32) - 1)
-
-/** Use a large prime for cycling through all oids */
-#define OID_INC            (999999937)
-
-static inline void
-oid_inc(daos_obj_id_t *oid)
-{
-	oid->hi = (oid->hi + OID_INC) & MAX_OID_HI;
-	/** Skip reserved entries */
-	if (oid->lo == RESERVED_LO && oid->hi <= 1)
-		oid->hi += OID_INC;
-}
-
 typedef uint64_t dfs_magic_t;
 typedef uint16_t dfs_sb_ver_t;
 typedef uint16_t dfs_layout_ver_t;
@@ -371,7 +356,9 @@ oid_gen(dfs_t *dfs, daos_oclass_id_t oclass, bool file, daos_obj_id_t *oid)
 
 	/** set oid and lo, bump the current hi value */
 	oid->lo = dfs->oid.lo;
-	oid_inc(&dfs->oid);
+	daos_obj_oid_cycle(&dfs->oid);
+	if (unlikely(dfs->oid.lo == RESERVED_LO && dfs->oid.hi <= 1))
+		daos_obj_oid_cycle(&dfs->oid); /* Avoid reserved oids */
 	oid->hi = dfs->oid.hi;
 	D_MUTEX_UNLOCK(&dfs->lock);
 

src/client/dfs/mnt.c

@@ -688,21 +688,17 @@ dfs_mount(daos_handle_t poh, daos_handle_t coh, int flags, dfs_t **_dfs)
 		dfs->last_hi = (unsigned int)d_rand();
 		/** Avoid potential conflict with SB or ROOT */
 		if (dfs->last_hi <= 1)
-			dfs->last_hi += OID_INC;
+			dfs->last_hi = 2;
 
 		rc = daos_cont_alloc_oids(coh, 1, &dfs->oid.lo, NULL);
 		if (rc) {
 			D_ERROR("daos_cont_alloc_oids() Failed, " DF_RC "\n", DP_RC(rc));
 			D_GOTO(err_root, rc = daos_der2errno(rc));
 		}
 
-		/*
-		 * if this is the first time we allocate on this container,
-		 * account 0 for SB, 1 for root obj.
-		 */
 		dfs->oid.hi = dfs->last_hi;
 		/** Increment so that dfs->last_hi is the last value */
-		oid_inc(&dfs->oid);
+		daos_obj_oid_cycle(&dfs->oid);
 	}
 
 	dfs->mounted = DFS_MOUNT;

src/include/daos_obj.h

@@ -1,5 +1,5 @@
 /**
- * (C) Copyright 2015-2023 Intel Corporation.
+ * (C) Copyright 2015-2024 Intel Corporation.
  *
  * SPDX-License-Identifier: BSD-2-Clause-Patent
  */
@@ -564,6 +564,21 @@ daos_obj_generate_oid(daos_handle_t coh, daos_obj_id_t *oid,
 		      enum daos_otype_t type, daos_oclass_id_t cid,
 		      daos_oclass_hints_t hints, uint32_t args);
 
+
+/**
+ * This function, if called 2^32 times will set oid->hi to every unique 32-bit
+ * value. The caller is responsible for setting the initial value, tracking the
+ * final value, and avoiding any values that are otherwise reserved.
+ *
+ * \param[in, out]	oid	oid to cycle
+ */
+static inline void
+daos_obj_oid_cycle(daos_obj_id_t *oid)
+{
+	/** Uses a large prime number to guarantee hitting every unique value */
+	oid->hi = (oid->hi + 999999937) & UINT_MAX;
+}
+
 /**
  * Open an DAOS object.
  *