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@redhat.com>
- remove magic number 8 and 64.
page size / sector size is 8 on x86, however on ia64 page size is
16kb.
blkring size is 64 on x86. however it's 128 on ia64.
- replace 0xFFFF with INVALID_GRANT_HANDLE
- don't map io ring into user space with uncachable.
kernel access the page with cacable and tapdisk uses memory barrier
so that it isn't necessary.
- remove printk warning and inserted new line.
- remove unused variable, page.
- add one BUG()
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
blktap currently uses a hardcoded major of 254 for the device. This is
not robust in anyway and needs to be dynamic.
Note: it is better not to have the daemon create the node, and have udev
create it instead. But since the daemon currently creates the node
anyway, it is still the way this is done. That change needs to be made
at another time.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Ewan Mellor
kfraser@localhost.localdomain
Andrew Warfield
kaf24@firebug.cl.cam.ac.uk
jchesterfield@dhcp92.uk.xensource.com