qemu/nbd
Eric Blake 7423f41782 nbd: Limit nbdflags to 16 bits
Rather than asserting that nbdflags is within range, just give
it the correct type to begin with :)  nbdflags corresponds to
the per-export portion of NBD Protocol "transmission flags", which
is 16 bits in response to NBD_OPT_EXPORT_NAME and NBD_OPT_GO.

Furthermore, upstream NBD has never passed the global flags to
the kernel via ioctl(NBD_SET_FLAGS) (the ioctl was first
introduced in NBD 2.9.22; then a latent bug in NBD 3.1 actually
tried to OR the global flags with the transmission flags, with
the disaster that the addition of NBD_FLAG_NO_ZEROES in 3.9
caused all earlier NBD 3.x clients to treat every export as
read-only; NBD 3.10 and later intentionally clip things to 16
bits to pass only transmission flags).  Qemu should follow suit,
since the current two global flags (NBD_FLAG_FIXED_NEWSTYLE
and NBD_FLAG_NO_ZEROES) have no impact on the kernel's behavior
during transmission.

CC: qemu-stable@nongnu.org
Signed-off-by: Eric Blake <eblake@redhat.com>

Message-Id: <1469129688-22848-3-git-send-email-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2016-08-03 18:44:56 +02:00
..
client.c nbd: Limit nbdflags to 16 bits 2016-08-03 18:44:56 +02:00
common.c nbd: Drop unused offset parameter 2016-07-20 14:11:54 +01:00
Makefile.objs nbd: Split nbd.c 2016-01-15 18:58:02 +01:00
nbd-internal.h nbd: Drop unused offset parameter 2016-07-20 14:11:54 +01:00
server.c nbd: Limit nbdflags to 16 bits 2016-08-03 18:44:56 +02:00