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authorEric Blake <eblake@redhat.com>2016-10-14 13:33:16 -0500
committerPaolo Bonzini <pbonzini@redhat.com>2016-11-02 09:28:56 +0100
commitb6f5d3b573fe43da1f9fa07b7454e4492f409411 (patch)
treebe19f967869577966cdbcfa26f1a21dfbfc5832a /nbd/nbd-internal.h
parent8b34a9dbc3f2c0afe3450cb20b94cc30f450e77b (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/nbd-internal.h')
-rw-r--r--nbd/nbd-internal.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/nbd/nbd-internal.h b/nbd/nbd-internal.h
index dd57e18833..eee20abc25 100644
--- a/nbd/nbd-internal.h
+++ b/nbd/nbd-internal.h
@@ -92,6 +92,7 @@
#define NBD_ENOMEM 12
#define NBD_EINVAL 22
#define NBD_ENOSPC 28
+#define NBD_ESHUTDOWN 108
static inline ssize_t read_sync(QIOChannel *ioc, void *buffer, size_t size)
{