9os

commit 79d65ee7842c7f23b7d07efbc4c99eb37cf00cba
parent bad3e003ee66b0292d1c37246def9b615374eae6
Author: Roberto E. Vargas Caballero <roberto.vargas@midokura.com>
Date:   Wed, 23 Nov 2022 14:12:45 +0100

os9: Don't copy mpoints in RFNAMEG

Instead of having an array of Mpoints this commit changes
the code to have an array of pointers to Mpoints that are
shared between different Nspaces.

Diffstat:
M
include/os9/os9.h
 | 
9
+++++++--
M
src/os9/alloc.c
 | 
31
+++++++++++++++++++++++++++++++
M
src/os9/dev/dev.c
 | 
78
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--------------------

3 files changed, 96 insertions(+), 22 deletions(-)
diff --git a/include/os9/os9.h b/include/os9/os9.h
@@ -48,6 +48,7 @@ typedef struct dir Dir;
 typedef struct mach Mach;
 typedef struct map Map;
 typedef struct page Page;
+typedef struct mpoint Mpoint;
 typedef struct nspace Nspace;
 typedef struct fdset Fdset;
 typedef struct ref Ref;
@@ -165,16 +166,17 @@ struct chan {
 };
 
 struct mpoint {
+	Ref ref;
 	Chan *new;
 	Chan *old;
 	mutex_t m;
+	Mpoint *next;
 };
 
-
 struct nspace {
 	Ref ref;
 	mutex_t m;
-	struct mpoint mpoints[NR_MPOINTS];
+	Mpoint *mpoints[NR_MPOINTS];
 	Nspace *next;
 };
 
@@ -273,12 +275,15 @@ extern Nspace *allocspace(void);
 extern Map *allocmap(void);
 extern Fdset *allocfds(void);
 extern Chan *allocchan(void);
+extern Mpoint *allocmpoint(void);
+
 extern void freeb(void *);
 extern void freep(Page *);
 extern void freespace(Nspace *);
 extern void freemap(Map *);
 extern void freefds(Fdset *);
 extern void freechan(Chan *);
+extern void freempoint(Mpoint *);
 extern void ialloc(void);
 
 /* map.c */
diff --git a/src/os9/alloc.c b/src/os9/alloc.c
@@ -23,6 +23,7 @@ static struct pool nspool;
 static struct pool mappool;
 static struct pool fdspool;
 static struct pool chanpool;
+static struct pool mpointpool;
 
 void
 freeb(void *bp)
@@ -271,6 +272,36 @@ freechan(Chan *c)
 	unlock(&chanpool.m);
 }
 
+Mpoint *
+allocmpoint(void)
+{
+	Mpoint *mp;
+
+	lock(&mpointpool.m);
+	if (mpointpool.list) {
+		mp = mpointpool.list;
+		mpointpool.list = mp->next;
+	} else {
+		if ((mp = alloc(sizeof(*mp))) == NULL)
+			return NULL;
+	}
+	unlock(&mpointpool.m);
+
+	return mp;
+}
+
+void
+freempoint(Mpoint *mp)
+{
+	if (!mp)
+		return;
+
+	lock(&mpointpool.m);
+	mp->next = mpointpool.list;
+	mpointpool.list = mp;
+	unlock(&mpointpool.m);
+}
+
 void
 ialloc(void)
 {
diff --git a/src/os9/dev/dev.c b/src/os9/dev/dev.c
@@ -62,14 +62,26 @@ err2:
 Nspace *
 newspace(Nspace *from)
 {
+	int i;
+	Mpoint *mp;
 	Nspace *ns;
 
 	if ((ns = allocspace()) == NULL)
 		return NULL;
-
-	*ns = (from) ? *from : (Nspace) {0};
+	memset(ns, 0, sizeof(*ns));
 	initref(&ns->ref);
 
+	if (!from)
+		return ns;
+
+	lock(&from->m);
+	for (i = 0; i <NR_MPOINTS; i++) {
+		mp = ns->mpoints[i] = from->mpoints[i];
+		if (mp)
+			incref(&mp->ref);
+	}
+	unlock(&from->m);
+
 	return ns;
 }
 
@@ -100,10 +112,30 @@ newfds(Fdset *from)
 }
 
 void
+delmpoint(Mpoint *mp)
+{
+	if (!decref(&mp->ref))
+		return;
+	delchan(mp->new);
+	delchan(mp->old);
+	freempoint(mp);
+}
+
+void
 delspace(Nspace *ns)
 {
+	int i;
+	Mpoint *mp;
+
 	if (!decref(&ns->ref))
 		return;
+
+	for (i = 0; i < NR_MPOINTS; ++i) {
+		mp = ns->mpoints[i];
+		if (!mp)
+			continue;
+		delmpoint(mp);
+	}
 	freespace(ns);
 }
 
@@ -247,11 +279,15 @@ buf2chan(Chan *c, void *dst, void *src, int nbytes, long len)
 static Chan *
 mntpoint(int type, Qid qid)
 {
+	int i;
 	Chan *cn;
-	struct mpoint *mp;
-	struct mpoint *mpoints = proc->ns->mpoints;
+	Mpoint *mp;
+	Nspace *ns = proc->ns;
 
-	for (mp = mpoints; mp < &mpoints[NR_MPOINTS]; mp++) {
+	lock(&ns->m);
+	for (i = 0; i < NR_MPOINTS; ++i) {
+		if ((mp = ns->mpoints[i]) == NULL)
+			continue;
 		lock(&mp->m);
 		if ((cn = mp->new) == NULL) {
 			unlock(&mp->m);
@@ -263,6 +299,7 @@ mntpoint(int type, Qid qid)
 		}
 		unlock(&mp->m);
 	}
+	unlock(&ns->m);
 
 	return NULL;
 }
@@ -736,8 +773,11 @@ addmntpoint(Chan *c, char *new)
 {
 	int i;
 	Chan *cn;
-	struct mpoint *mp;
-	struct mpoint *mpoints = proc->ns->mpoints;
+	Mpoint *mp;
+	Nspace *ns = proc->ns;
+
+	if ((mp = allocmpoint()) == NULL)
+		return -1;
 
 	if ((cn = namec(new, O_READ)) == NULL)
 		goto err0;
@@ -747,28 +787,26 @@ addmntpoint(Chan *c, char *new)
 		goto err1;
 	}
 
-	for (i = NR_MPOINTS-1; i >= 0; i--) {
-		mp = &mpoints[i];
-		lock(&mp->m);
-		if (!mp->new)
-			break;
-		unlock(&mp->m);
-	}
-
-	if (i < 0) {
-		errno = ENOMEM;
-		goto err1;
-	}
+	lock(&ns->m);
+	for (i = NR_MPOINTS-1; i >= 0 && ns->mpoints[i]; i--)
+		;
+	if (i < 0)
+		goto err2;
 
+	ns->mpoints[i] = mp;
 	mp->new = cn;
 	mp->old = c;
-	unlock(&mp->m);
+	unlock(&ns->m);
 
 	return 0;
 
+err2:
+	errno = ENOMEM;
+	unlock(&ns->m);
 err1:
 	delchan(cn);
 err0:
+	delmpoint(mp);
 	return -1;
 }