Properly set size of the file_zone to match kern.maxfiles parameter.

Otherwise the parameter is no-op, since zone by default limits number
of descriptors to some 12K entries. Attempt to allocate more ends up
sleeping on zonelimit.

MFC after:	2 weeks

1 files changed, 36 insertions, 3 deletions

diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index 5174c15..683da72 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -2801,8 +2801,38 @@ DB_SHOW_COMMAND(files, db_show_files)
 SYSCTL_INT(_kern, KERN_MAXFILESPERPROC, maxfilesperproc, CTLFLAG_RW,
     &maxfilesperproc, 0, "Maximum files allowed open per process");
 
-SYSCTL_INT(_kern, KERN_MAXFILES, maxfiles, CTLFLAG_RW,
-    &maxfiles, 0, "Maximum number of files");
+/*
+ * User has changed the maximum number of files.
+ * This may require us to change size of the zone.
+ */
+static int
+sysctl_kern_maxfiles(SYSCTL_HANDLER_ARGS)
+{
+	int error;
+	int new_maxfiles;
+
+	new_maxfiles = maxfiles;
+	error = sysctl_handle_int(oidp, &new_maxfiles, sizeof(int), req);
+	if (error != 0 || req->newptr == NULL)
+		return (error);
+	if (new_maxfiles <= 0) {
+		return (EINVAL);
+	}
+	maxfiles = new_maxfiles;
+	EVENTHANDLER_INVOKE(maxfiles_change);
+	return (0);
+}
+
+static void
+file_zone_change(void *tag)
+{
+
+	uma_zone_set_max(file_zone, maxfiles);
+}
+
+SYSCTL_PROC(_kern, OID_AUTO, maxfiles, CTLTYPE_INT|CTLFLAG_RW,
+    __DEVOLATILE(int *, &maxfiles), 0, sysctl_kern_maxfiles, "IU",
+    "Maximum number of files");
 
 SYSCTL_INT(_kern, OID_AUTO, openfiles, CTLFLAG_RD,
     __DEVOLATILE(int *, &openfiles), 0, "System-wide number of open files");
@@ -2814,10 +2844,13 @@ filelistinit(void *dummy)
 
 	file_zone = uma_zcreate("Files", sizeof(struct file), NULL, NULL,
 	    NULL, NULL, UMA_ALIGN_PTR, 0);
+	uma_zone_set_max(file_zone, maxfiles);
+	EVENTHANDLER_REGISTER(maxfiles_change, file_zone_change, NULL,
+	    EVENTHANDLER_PRI_FIRST);
 	mtx_init(&sigio_lock, "sigio lock", NULL, MTX_DEF);
 	mtx_init(&fdesc_mtx, "fdesc", NULL, MTX_DEF);
 }
-SYSINIT(select, SI_SUB_LOCK, SI_ORDER_FIRST, filelistinit, NULL)
+SYSINIT(select, SI_SUB_EVENTHANDLER+1, SI_ORDER_MIDDLE, filelistinit, NULL)
 
 /*-------------------------------------------------------------------*/