diff options
| author | Eric Blake <eblake@redhat.com> | 2017-07-07 15:30:47 -0500 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2017-07-14 12:04:42 +0200 |
| commit | 8ecaeae82241b6e317d19e5558e52f9e2f979f74 (patch) | |
| tree | 68272b3eea7fef4e8dd0ad8bf1a1d78741272a3d /nbd/nbd-internal.h | |
| parent | f37708f6b8e0bef0dd85c6aad7fc2062071f8227 (diff) | |
nbd: Implement NBD_OPT_GO on client
NBD_OPT_EXPORT_NAME is lousy: per the NBD protocol, any failure
requires the server to close the connection rather than report an
error to us. Therefore, upstream NBD recently added NBD_OPT_GO as
the improved version of the option that does what we want [1]: it
reports sane errors on failures, and on success provides at least
as much info as NBD_OPT_EXPORT_NAME.
[1] https://github.com/NetworkBlockDevice/nbd/blob/extension-info/doc/proto.md
This is a first cut at use of the information types. Note that we
do not need to use NBD_OPT_INFO, and that use of NBD_OPT_GO means
we no longer have to use NBD_OPT_LIST to learn whether a server
requires TLS (this requires servers that gracefully handle unknown
NBD_OPT, many servers prior to qemu 2.5 were buggy, but I have patched
qemu, upstream nbd, and nbdkit in the meantime, in part because of
interoperability testing with this patch). We still fall back to
NBD_OPT_LIST when NBD_OPT_GO is not supported on the server, as it
is still one last chance for a nicer error message. Later patches
will use further info, like NBD_INFO_BLOCK_SIZE.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20170707203049.534-8-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'nbd/nbd-internal.h')
| -rw-r--r-- | nbd/nbd-internal.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/nbd/nbd-internal.h b/nbd/nbd-internal.h index bf95601ff5..4065bc68ac 100644 --- a/nbd/nbd-internal.h +++ b/nbd/nbd-internal.h @@ -37,8 +37,11 @@ * https://github.com/yoe/nbd/blob/master/doc/proto.md */ +/* Size of all NBD_OPT_*, without payload */ #define NBD_REQUEST_SIZE (4 + 2 + 2 + 8 + 8 + 4) +/* Size of all NBD_REP_* sent in answer to most NBD_OPT_*, without payload */ #define NBD_REPLY_SIZE (4 + 4 + 8) + #define NBD_REQUEST_MAGIC 0x25609513 #define NBD_REPLY_MAGIC 0x67446698 #define NBD_OPTS_MAGIC 0x49484156454F5054LL |