[Xen-devel] [PATCH] Fix 32-bit sector number overflow in blktap userspace

["Daniel P. Berrange" <berrange@xxxxxxxxxx>]

While the kernel side of blktap drivers is using 64-bit sector numbers
correctly when reporting disk sizing, the userspace parts where this
dat is actually generated is truncating at 32-bit. There are 3 variables
related to disk sizing which are used in the kernel/userspace code 'size',
'sector size' & 'info'. In kernel space these are treated as being 
unsigned long long, unsigned long, and unsigned int, respectively. In
the blktap userspace code this were all varyingly long, unsigned long.
This mismatch caused 32-bit wraparound on large disks. The attached patch
updates the blktap userspace to use the same data types as kernel space
for all these params, thus both fixing the 32-bit bug & giving the code
consistency.

This patch has been tested both by comparing /proc/partitions in the
guest, with the image size seen in the host, and by using Stephen
Tweedie's 'verify-data' tool on a variety of multi-TB sized disks.

  Signed-off-by: Daniel P. Berrange <berrange@xxxxxxxxxx>

(Reposted from 
http://lists.xensource.com/archives/html/xen-devel/2006-11/msg01131.html)

Regards,
Dan.
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Attachment: blktap-2tb-2.patch
Description: Text document

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