libkvm - Adjust kvm_getswapinfo() to use the new vm.swap_info_array sysctl

* kvm_getswapinfo() attempts to use the new sysctl and if it fails, or
  if the kvm is operating on a kernel core file, reverts to the namelist.

diff --git a/lib/libkvm/kvm_getswapinfo.c b/lib/libkvm/kvm_getswapinfo.c
index 66c9259..3e7915d 100644 (file)
--- a/lib/libkvm/kvm_getswapinfo.c
+++ b/lib/libkvm/kvm_getswapinfo.c
@@ -43,6 +43,8 @@
 #include <sys/stat.h>
 #include <sys/conf.h>
 #include <sys/blist.h>
+#include <sys/sysctl.h>
+#include <vm/vm_param.h>
 
 #include <err.h>
 #include <fcntl.h>
@@ -53,6 +55,9 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <limits.h>
+
+#include "kvm_private.h"
 
 static struct nlist kvm_swap_nl[] = {
        { "_swapblist" },       /* new radix swap list          */
@@ -74,6 +79,8 @@ static int dmmax;
 
 static void getswapinfo_radix(kvm_t *kd, struct kvm_swap *swap_ary,
                              int swap_max, int flags);
+static int kvm_getswapinfo_sysctl(kvm_t *kd, struct kvm_swap *swap_ary,
+                             int swap_max, int flags);
 
 #define        SVAR(var) __STRING(var) /* to force expansion */
 #define        KGET(idx, var)                                                  \
@@ -102,7 +109,7 @@ kvm_getswapinfo(
        int swap_max, 
        int flags
 ) {
-       int ti = 0;
+       int ti;
 
        /*
         * clear cache
@@ -113,6 +120,15 @@ kvm_getswapinfo(
        }
 
        /*
+        * Use sysctl if possible
+        */
+       if (kvm_ishost(kd) && (flags & SWIF_DUMP_TREE) == 0) {
+               ti = kvm_getswapinfo_sysctl(kd, swap_ary, swap_max, flags);
+               if (ti >= 0)
+                       return(ti);
+       }
+
+       /*
         * namelist
         */
        if (kvm_swap_nl_cached == 0) {
@@ -158,7 +174,6 @@ kvm_getswapinfo(
                kvm_swap_nl_cached = 1;
        }
 
-
        {
                struct swdevt *sw;
                int i;
@@ -462,3 +477,69 @@ getswapinfo_radix(kvm_t *kd, struct kvm_swap *swap_ary, int swap_max, int flags)
                swap_ary[0].ksw_used -= blcopy.bl_free;
        }
 }
+
+static
+int
+kvm_getswapinfo_sysctl(kvm_t *kd, struct kvm_swap *swap_ary,
+                      int swap_max, int flags)
+{
+       size_t bytes = 0;
+       size_t ksize;
+       int ti;
+       int n;
+       int i;
+       char *xswbuf;
+       struct xswdev *xsw;
+
+       if (sysctlbyname("vm.swap_info_array", NULL, &bytes, NULL, 0) < 0)
+               return(-1);
+       if (bytes == 0)
+               return(-1);
+       xswbuf = malloc(bytes);
+       if (sysctlbyname("vm.swap_info_array", xswbuf, &bytes, NULL, 0) < 0)
+               return(-1);
+       if (bytes == 0)
+               return(-1);
+
+       bzero(swap_ary, sizeof(struct kvm_swap) * swap_max);
+       --swap_max;
+
+       /*
+        * Calculate size of xsw entry returned by kernel (it can be larger
+        * than the one we have if there is a version mismatch).
+        *
+        * Then iterate the list looking for live swap devices.
+        */
+       ksize = ((struct xswdev *)xswbuf)->xsw_size;
+       n = (int)(bytes / ksize);
+
+       for (i = ti = 0; i < n && ti < swap_max; ++i) {
+               xsw = (void *)((char *)xswbuf + i * ksize);
+
+               if ((xsw->xsw_flags & SW_FREED) == 0)
+                       continue;
+
+               swap_ary[ti].ksw_total = xsw->xsw_nblks;
+               swap_ary[ti].ksw_used = xsw->xsw_used;
+               swap_ary[ti].ksw_flags = xsw->xsw_flags;
+
+               if (xsw->xsw_dev == NODEV) {
+                       snprintf(
+                           swap_ary[ti].ksw_devname,
+                           sizeof(swap_ary[ti].ksw_devname),
+                           "%s",
+                           "[NFS swap]"
+                       );
+               } else {
+                       snprintf(
+                           swap_ary[ti].ksw_devname,
+                           sizeof(swap_ary[ti].ksw_devname),
+                           "%s%s",
+                           ((flags & SWIF_DEV_PREFIX) ? _PATH_DEV : ""),
+                           devname(xsw->xsw_dev, S_IFCHR)
+                       );
+               }
+               ++ti;
+       }
+       return(ti);
+}