Am 06.02.2015 um 12:24 hat Denis V. Lunev geschrieben:
> nbd_co_discard calls nbd_client_session_co_discard which uses uint32_t
> as the length in bytes of the data to discard due to the following
> definition:
>
> struct nbd_request {
> uint32_t magic;
> uint32_t type;
> uint64_t handle;
> uint64_t from;
> uint32_t len; <-- the length of data to be discarded, in bytes
> } QEMU_PACKED;
>
> Thus we should limit bl_max_discard to UINT32_MAX >> BDRV_SECTOR_BITS to
> avoid overflow.
>
> NBD read/write code uses the same structure for transfers. Fix
> max_transfer_length accordingly.
>
> Signed-off-by: Denis V. Lunev <d...@openvz.org>
> CC: Peter Lieven <p...@kamp.de>
> CC: Kevin Wolf <kw...@redhat.com>
Thanks, I have applied both Peter's and your patch. Can you guys please
check whether the current state of my block branch is correct or whether
I forgot to include or remove some patch?
By the way, I don't think this NBD patch is strictly necessary as you'll
have a hard time finding a platform where INT_MAX > UINT32_MAX, but I
think it's good documentation at least and a safeguard if we ever decide
to lift the general block layer restrictions.
Kevin
