diff options
| author | Eric Blake <eblake@redhat.com> | 2016-10-14 13:33:16 -0500 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-11-02 09:28:56 +0100 |
| commit | b6f5d3b573fe43da1f9fa07b7454e4492f409411 (patch) | |
| tree | be19f967869577966cdbcfa26f1a21dfbfc5832a /nbd/server.c | |
| parent | 8b34a9dbc3f2c0afe3450cb20b94cc30f450e77b (diff) | |
nbd: Improve server handling of shutdown requests
NBD commit 6d34500b clarified how clients and servers are supposed
to behave before closing a connection. It added NBD_REP_ERR_SHUTDOWN
(for the server to announce it is about to go away during option
haggling, so the client should quit sending NBD_OPT_* other than
NBD_OPT_ABORT) and ESHUTDOWN (for the server to announce it is about
to go away during transmission, so the client should quit sending
NBD_CMD_* other than NBD_CMD_DISC). It also clarified that
NBD_OPT_ABORT gets a reply, while NBD_CMD_DISC does not.
This patch merely adds the missing reply to NBD_OPT_ABORT and teaches
the client to recognize server errors. Actually teaching the server
to send NBD_REP_ERR_SHUTDOWN or ESHUTDOWN would require knowing that
the server has been requested to shut down soon (maybe we could do
that by installing a SIGINT handler in qemu-nbd, which transitions
from RUNNING to a new state that waits for the client to react,
rather than just out-right quitting - but that's a bigger task for
another day).
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-15-git-send-email-eblake@redhat.com>
[Move dummy ESHUTDOWN to include/qemu/osdep.h. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'nbd/server.c')
| -rw-r--r-- | nbd/server.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/nbd/server.c b/nbd/server.c index afc1ec47b3..0b50caad9e 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -39,6 +39,8 @@ static int system_errno_to_nbd_errno(int err) case EFBIG: case ENOSPC: return NBD_ENOSPC; + case ESHUTDOWN: + return NBD_ESHUTDOWN; case EINVAL: default: return NBD_EINVAL; @@ -527,6 +529,10 @@ static int nbd_negotiate_options(NBDClient *client) if (ret < 0) { return ret; } + /* Let the client keep trying, unless they asked to quit */ + if (clientflags == NBD_OPT_ABORT) { + return -EINVAL; + } break; } } else if (fixedNewstyle) { @@ -539,6 +545,10 @@ static int nbd_negotiate_options(NBDClient *client) break; case NBD_OPT_ABORT: + /* NBD spec says we must try to reply before + * disconnecting, but that we must also tolerate + * guests that don't wait for our reply. */ + nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, clientflags); return -EINVAL; case NBD_OPT_EXPORT_NAME: |