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author | Eric Blake <eblake@redhat.com> | 2016-10-14 13:33:16 -0500 |
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committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-11-02 09:28:56 +0100 |
commit | b6f5d3b573fe43da1f9fa07b7454e4492f409411 (patch) | |
tree | be19f967869577966cdbcfa26f1a21dfbfc5832a /nbd/client.c | |
parent | 8b34a9dbc3f2c0afe3450cb20b94cc30f450e77b (diff) | |
download | qemu-b6f5d3b573fe43da1f9fa07b7454e4492f409411.zip qemu-b6f5d3b573fe43da1f9fa07b7454e4492f409411.tar.gz qemu-b6f5d3b573fe43da1f9fa07b7454e4492f409411.tar.bz2 |
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/client.c')
-rw-r--r-- | nbd/client.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/nbd/client.c b/nbd/client.c index 7bdce53..7db4301 100644 --- a/nbd/client.c +++ b/nbd/client.c @@ -40,6 +40,9 @@ static int nbd_errno_to_system_errno(int err) case NBD_ENOSPC: ret = ENOSPC; break; + case NBD_ESHUTDOWN: + ret = ESHUTDOWN; + break; default: TRACE("Squashing unexpected error %d to EINVAL", err); /* fallthrough */ @@ -239,11 +242,21 @@ static int nbd_handle_reply_err(QIOChannel *ioc, nbd_opt_reply *reply, reply->option); break; + case NBD_REP_ERR_PLATFORM: + error_setg(errp, "Server lacks support for option %" PRIx32, + reply->option); + break; + case NBD_REP_ERR_TLS_REQD: error_setg(errp, "TLS negotiation required before option %" PRIx32, reply->option); break; + case NBD_REP_ERR_SHUTDOWN: + error_setg(errp, "Server shutting down before option %" PRIx32, + reply->option); + break; + default: error_setg(errp, "Unknown error code when asking for option %" PRIx32, reply->option); @@ -785,6 +798,11 @@ ssize_t nbd_receive_reply(QIOChannel *ioc, NBDReply *reply) reply->error = nbd_errno_to_system_errno(reply->error); + if (reply->error == ESHUTDOWN) { + /* This works even on mingw which lacks a native ESHUTDOWN */ + LOG("server shutting down"); + return -EINVAL; + } TRACE("Got reply: { magic = 0x%" PRIx32 ", .error = % " PRId32 ", handle = %" PRIu64" }", magic, reply->error, reply->handle); |