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authorEric Blake <eblake@redhat.com>2016-07-21 13:34:46 -0600
committerPaolo Bonzini <pbonzini@redhat.com>2016-08-03 18:44:56 +0200
commit7423f417827146f956df820f172d0bf80a489495 (patch)
treec344d494cc4fab46a7bb1daacb0088bc35e9ee1f /block
parent5bee0f4717c4c67394aaade0c5a9cee3d42cc614 (diff)
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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>
Diffstat (limited to 'block')
-rw-r--r--block/nbd-client.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/block/nbd-client.h b/block/nbd-client.h
index fa9817b..044aca4 100644
--- a/block/nbd-client.h
+++ b/block/nbd-client.h
@@ -20,7 +20,7 @@
typedef struct NbdClientSession {
QIOChannelSocket *sioc; /* The master data channel */
QIOChannel *ioc; /* The current I/O channel which may differ (eg TLS) */
- uint32_t nbdflags;
+ uint16_t nbdflags;
off_t size;
CoMutex send_mutex;