[Qemu-devel] [PATCH 5/7] block/vpc: Fix size calculation

[Stefan Weil]

The size calculated from the CHS values is not the real image (disk) size,
but usually a smaller value (this is caused by rounding effects).

Only older operating systems use CHS. Such guests won't be able to use
the whole disk.

This patch fixes https://bugs.launchpad.net/qemu/+bug/1105670/.

Signed-off-by: Stefan Weil <address@hidden>
---
 block/vpc.c |    9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/block/vpc.c b/block/vpc.c
index fff103b..799b1c9 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -198,11 +198,10 @@ static int vpc_open(BlockDriverState *bs, int flags)
     /* Write 'checksum' back to footer, or else will leave it with zero. */
     footer->checksum = be32_to_cpu(checksum);
 
-    // The visible size of a image in Virtual PC depends on the geometry
-    // rather than on the size stored in the footer (the size in the footer
-    // is too large usually)
-    bs->total_sectors = (int64_t)
-        be16_to_cpu(footer->cyls) * footer->heads * footer->secs_per_cyl;
+    /* The visible size of an image in Virtual PC may depend on the geometry
+     * rather than on the size stored in the footer (the size in the footer
+     * is usually larger). Nevertheless we must use the real size here. */
+    bs->total_sectors = be64_to_cpu(footer->size) / 512;
 
     /* Allow a maximum disk size of approximately 2 TB */
     if (bs->total_sectors >= 65535LL * 255 * 255) {
-- 
1.7.10.4