Am 06.02.2015 um 12:59 hat Denis V. Lunev geschrieben:
On 06/02/15 14:53, Kevin Wolf wrote:
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 <address@hidden>
CC: Peter Lieven <address@hidden>
CC: Kevin Wolf <address@hidden>
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?
can you give me tree URL?
Sure:
git: git://repo.or.cz/qemu/kevin.git block
Web: http://repo.or.cz/w/qemu/kevin.git/shortlog/refs/heads/block
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
nope, it is absolutely mandatory
stdint.h:
/* Limit of `size_t' type. */
# if __WORDSIZE == 64
# define SIZE_MAX (18446744073709551615UL)
# else
# define SIZE_MAX (4294967295U)
# endif
But Peter defined it like this:
#define BDRV_REQUEST_MAX_SECTORS MIN(SIZE_MAX >> BDRV_SECTOR_BITS, \
INT_MAX >> BDRV_SECTOR_BITS)
And having integers with more the 32 bits is at least unusual. I don't
know of any platform that has them.
Anyway, as I said, your patch is good documentation, so I'm happy to
apply it nevertheless.
Kevin