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 <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?
can you give me tree URL?

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

Den

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