[libvirt] [PATCH] Fix sparse volume allocation reporting

[Cole Robinson <crobinso redhat com>]

I have a sparse volume with a capacity of 1000M, and an allocation of a
little over 750M. 'du' prints the correct sizes, but 'virsh vol-dumpxml'
shows:

    <capacity>1048576000</capacity>
  <allocation>6406307840</allocation>

This is because we were calculating the allocation size using the
requested fs block size, instead of what stat actually uses as a block
size (DEV_BSIZE in sys/params.h). sys/params.h looks to be present in
mingw32-runtime, so I didn't add a configure check for it.

The attached patch fixes allocation listing for me.

Thanks,
Cole

diff --git a/src/storage_backend.c b/src/storage_backend.c
index 787630c..54e9289 100644
--- a/src/storage_backend.c
+++ b/src/storage_backend.c
@@ -36,6 +36,7 @@
 #include <fcntl.h>
 #include <stdint.h>
 #include <sys/stat.h>
+#include <sys/param.h>
 #include <dirent.h>
 
 #if HAVE_SELINUX
@@ -204,8 +205,15 @@ virStorageBackendUpdateVolTargetInfoFD(virConnectPtr conn,
     if (allocation) {
         if (S_ISREG(sb.st_mode)) {
 #ifndef __MINGW32__
-            *allocation = (unsigned long long)sb.st_blocks *
-                (unsigned long long)sb.st_blksize;
+
+            unsigned long long blksize;
+#ifdef DEV_BSIZE
+            blksize = (unsigned long long) DEV_BSIZE;
+#else
+            blksize = (unsigned long long)sb.st_blksize;
+#endif
+            *allocation = (unsigned long long)sb.st_blocks * blksize;
+
 #else
             *allocation = sb.st_size;
 #endif