Change the way information about swap devices is exported to be more

canonical: define a versioned struct xswdev, and add a sysctl node
handler that allows the user to get this structure for a certain device
index by specifying this index as last element of the MIB.
This new node handler, vm.swap_info, replaces the old vm.nswapdev
and vm.swapdevX.* (where X was the index) sysctls.

2 files changed, 46 insertions, 28 deletions

diff --git a/sys/vm/vm_param.h b/sys/vm/vm_param.h
index a0809fe..7237638 100644
--- a/sys/vm/vm_param.h
+++ b/sys/vm/vm_param.h
@@ -105,6 +105,18 @@
 }
 
 /*
+ * Structure for swap device statistics
+ */
+#define XSWDEV_VERSION	1
+struct xswdev {
+	u_int	xsw_version;
+	udev_t	xsw_dev;
+	int	xsw_flags;
+	int	xsw_nblks;
+	int     xsw_used;
+};
+
+/*
  *	Return values from the VM routines.
  */
 #define	KERN_SUCCESS		0
diff --git a/sys/vm/vm_swap.c b/sys/vm/vm_swap.c
index 5904395..168f5cf 100644
--- a/sys/vm/vm_swap.c
+++ b/sys/vm/vm_swap.c
@@ -55,6 +55,7 @@
 #include <vm/vm.h>
 #include <vm/vm_extern.h>
 #include <vm/vm_zone.h>
+#include <vm/vm_param.h>
 #include <vm/swap_pager.h>
 
 /*
@@ -69,9 +70,6 @@ struct swdevt *swdevt = should_be_malloced;
 static int nswap;		/* first block after the interleaved devs */
 int nswdev = NSWAPDEV;
 int vm_swap_size;
-static int ncswdev = 0;         /* # of configured swap devs */
-SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, 
-   &ncswdev, 0, "Number of swap devices");
 
 static int swapdev_strategy __P((struct vop_strategy_args *ap));
 struct vnode *swapdev_vp;
@@ -250,8 +248,6 @@ swaponvp(p, vp, dev, nblks)
 	swblk_t dvbase;
 	int error;
 	u_long aligned_nblks;
-	struct sysctl_oid *oid;
-	char name[11];
 
 	if (!swapdev_vp) {
 		error = getnewvnode(VT_NON, NULL, swapdev_vnodeop_p,
@@ -334,29 +330,39 @@ swaponvp(p, vp, dev, nblks)
 		blist_free(swapblist, vsbase, blk);
 		vm_swap_size += blk;
 	}
-	/* 
-	 * Add sysctl entries for new swap area. XXX: if some day swap devices 
-	 * can be removed, add an oid member to swdevt.
-	 */
-	if (snprintf(name, sizeof(name), "swapdev%d", ncswdev) < sizeof(name)) {
-		oid = SYSCTL_ADD_NODE(NULL, SYSCTL_STATIC_CHILDREN(_vm), 
-		    OID_AUTO, name, CTLFLAG_RD, NULL, "Swap device stats");
-		if (oid != NULL) {
-			SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(oid), OID_AUTO, 
-			    "flags", CTLFLAG_RD, &sp->sw_flags, 0, "Flags");
-			SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(oid), OID_AUTO, 
-			    "nblks", CTLFLAG_RD, &sp->sw_nblks, 0, 
-			    "Number of blocks");
-			SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(oid), OID_AUTO, 
-			    "used", CTLFLAG_RD, &sp->sw_used, 0, 
-			    "Number of blocks in use");
-			SYSCTL_ADD_OPAQUE(NULL, SYSCTL_CHILDREN(oid), OID_AUTO, 
-			    "dev", CTLFLAG_RD, &sp->sw_dev, sizeof(sp->sw_dev), 
-			    "T,dev_t", "Device");
-		}
-	} else
-		printf("XXX: swaponvp() name buffer too small!\n");
-	ncswdev++;
 
 	return (0);
 }
+
+static int
+sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS)
+{
+	int	*name = (int *)arg1;
+	int	error, i, n;
+	struct xswdev xs;
+	struct swdevt *sp;
+
+	if (arg2 != 1) /* name length */
+		return (EINVAL);
+
+	for (sp = swdevt, i = 0, n = 0 ; i < nswdev; i++, sp++) {
+		if (sp->sw_vp) {
+			if (n == *name) {
+				xs.xsw_version = XSWDEV_VERSION;
+				xs.xsw_dev = sp->sw_dev;
+				xs.xsw_flags = sp->sw_flags;
+				xs.xsw_nblks = sp->sw_nblks;
+				xs.xsw_used = sp->sw_used;
+
+				error = SYSCTL_OUT(req, &xs, sizeof(xs));
+				return (error);
+			}
+			n++;
+		}
+
+	}
+	return (ENOENT);
+}
+
+SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD, sysctl_vm_swap_info,
+    "Swap statistics by device");