qemu-irix/nbd
Eric Blake 97b5a97f2f 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>
(cherry picked from commit 7423f41782)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
2016-08-05 16:19:20 -05:00
..
Makefile.objs
client.c nbd: Limit nbdflags to 16 bits 2016-08-05 16:19:20 -05:00
common.c nbd: do not hang nbd_wr_syncv if outside a coroutine and no available data 2016-04-08 00:07:44 +02:00
nbd-internal.h nbd: Avoid bitrot in TRACE() usage 2016-04-08 00:07:43 +02:00
server.c nbd: Limit nbdflags to 16 bits 2016-08-05 16:19:20 -05:00