From: Vitaly Kuznetsov <vkuzn...@redhat.com>
It was found that 'qemu-nbd' is not able to work with some disk images
exported from Azure. Looking at the 512b footer (which contains VPC
metadata):
00000000 63 6f 6e 65 63 74 69 78 00 00 00 02 00 01 00 00 |conectix........|
00000010 ff ff ff ff ff ff ff ff 2e c7 9b 96 77 61 00 00 |............wa..|
00000020 00 07 00 00 57 69 32 6b 00 00 00 01 40 00 00 00 |....Wi2k....@...|
00000030 00 00 00 01 40 00 00 00 28 a2 10 3f 00 00 00 02 |....@...(..?....|
00000040 ff ff e7 47 8c 54 df 94 bd 35 71 4c 94 5f e5 44 |...G.T...5qL._.D|
00000050 44 53 92 1a 00 00 00 00 00 00 00 00 00 00 00 00 |DS..............|
00000060 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
we can see that Azure uses a different 'Creator application' --
'wa\0\0' (offset 0x1c, likely reads as 'Windows Azure') and QEMU uses this
field to determine how it can get image size. Apparently, Azure uses 'new'
method, just like Hyper-V.
Overall, it seems that only VPC and old QEMUs need to be ignored as all new
creator apps seem to have reliable current_size. Invert the logic and make
'current_size' method the default to avoid adding every new creator app to
the list.
Signed-off-by: Vitaly Kuznetsov <vkuzn...@redhat.com>
Message-ID: <20241212134504.1983757-3-vkuzn...@redhat.com>
Reviewed-by: Kevin Wolf <kw...@redhat.com>
Signed-off-by: Kevin Wolf <kw...@redhat.com>
---
block/vpc.c | 8 +++-----
1 file changed, 3 insertions(+), 5 deletions(-)
diff --git a/block/vpc.c b/block/vpc.c
index cb0773914c..fb64ea6040 100644
--- a/block/vpc.c
+++ b/block/vpc.c
@@ -237,6 +237,7 @@ static void vpc_parse_options(BlockDriverState *bs,
QemuOpts *opts,
* 'd2v ' : current_size Disk2vhd
* 'tap\0' : current_size XenServer
* 'CTXS' : current_size XenConverter
+ * 'wa\0\0': current_size Azure
*
* The user can override the table values via drive options, however
* even with an override we will still use current_size for images
@@ -244,11 +245,8 @@ static void vpc_parse_options(BlockDriverState *bs,
QemuOpts *opts,
*/
static bool vpc_ignore_current_size(VHDFooter *footer)
{
- return !!strncmp(footer->creator_app, "win ", 4) &&
- !!strncmp(footer->creator_app, "qem2", 4) &&
- !!strncmp(footer->creator_app, "d2v ", 4) &&
- !!strncmp(footer->creator_app, "CTXS", 4) &&
- !!memcmp(footer->creator_app, "tap", 4));
+ return !strncmp(footer->creator_app, "vpc ", 4) ||
+ !strncmp(footer->creator_app, "qemu", 4);
}
static int vpc_open(BlockDriverState *bs, QDict *options, int flags,
--
2.48.1
