[PATCH v6 02/14] tools/xenstore: manage per-transaction domain accounting data in an array

[Juergen Gross <jgross@suse.com>]

In order to prepare keeping accounting data in an array instead of
using independent fields, switch the struct changed_domain accounting
data to that scheme, for now only using an array with one element.

In order to be able to extend this scheme add the needed indexing enum
to xenstored_domain.h.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
---
V2:
- make "what" parameter of acc_add_changed_dom() an enum type, and
  assert() that it won't exceed the accounting array (Julien Grall)
---
 tools/xenstore/xenstored_domain.c | 19 +++++++++++--------
 tools/xenstore/xenstored_domain.h | 10 ++++++++++
 2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/tools/xenstore/xenstored_domain.c b/tools/xenstore/xenstored_domain.c
index dbbf97accc..609a9a13ab 100644
--- a/tools/xenstore/xenstored_domain.c
+++ b/tools/xenstore/xenstored_domain.c
@@ -99,8 +99,8 @@ struct changed_domain
 	/* Identifier of the changed domain. */
 	unsigned int domid;
 
-	/* Amount by which this domain's nbentry field has changed. */
-	int nbentry;
+	/* Accounting data. */
+	int acc[ACC_TR_N];
 };
 
 static struct hashtable *domhash;
@@ -550,7 +550,7 @@ int acc_fix_domains(struct list_head *head, bool chk_quota, bool update)
 	int cnt;
 
 	list_for_each_entry(cd, head, list) {
-		cnt = domain_nbentry_fix(cd->domid, cd->nbentry, update);
+		cnt = domain_nbentry_fix(cd->domid, cd->acc[ACC_NODES], update);
 		if (!update) {
 			if (chk_quota && cnt >= quota_nb_entry_per_domain)
 				return ENOSPC;
@@ -595,19 +595,21 @@ static struct changed_domain *acc_get_changed_domain(const void *ctx,
 	return cd;
 }
 
-static int acc_add_dom_nbentry(const void *ctx, struct list_head *head, int val,
-			       unsigned int domid)
+static int acc_add_changed_dom(const void *ctx, struct list_head *head,
+			       enum accitem what, int val, unsigned int domid)
 {
 	struct changed_domain *cd;
 
+	assert(what < ARRAY_SIZE(cd->acc));
+
 	cd = acc_get_changed_domain(ctx, head, domid);
 	if (!cd)
 		return 0;
 
 	errno = 0;
-	cd->nbentry += val;
+	cd->acc[what] += val;
 
-	return cd->nbentry;
+	return cd->acc[what];
 }
 
 static void domain_conn_reset(struct domain *domain)
@@ -1071,7 +1073,8 @@ static int domain_nbentry_add(struct connection *conn, unsigned int domid,
 
 	if (conn && conn->transaction) {
 		head = transaction_get_changed_domains(conn->transaction);
-		ret = acc_add_dom_nbentry(conn->transaction, head, add, domid);
+		ret = acc_add_changed_dom(conn->transaction, head, ACC_NODES,
+					  add, domid);
 		if (errno) {
 			fail_transaction(conn->transaction);
 			return -1;
diff --git a/tools/xenstore/xenstored_domain.h b/tools/xenstore/xenstored_domain.h
index 279cccb3ad..40803574f6 100644
--- a/tools/xenstore/xenstored_domain.h
+++ b/tools/xenstore/xenstored_domain.h
@@ -19,6 +19,16 @@
 #ifndef _XENSTORED_DOMAIN_H
 #define _XENSTORED_DOMAIN_H
 
+/*
+ * All accounting data is stored in a per-domain array.
+ * Depending on the account item there might be other scopes as well, like e.g.
+ * a per transaction array.
+ */
+enum accitem {
+	ACC_NODES,
+	ACC_TR_N,		/* Number of elements per transaction. */
+};
+
 void handle_event(void);
 
 void check_domains(void);
-- 
2.35.3