nbd-client: fix handling of hungup connections

After the switch to reading replies in a coroutine, nothing is
reentering pending receive coroutines if the connection hangs.
Move nbd_recv_coroutines_enter_all to the reply read coroutine,
which is the place where hangups are detected.  nbd_teardown_connection
can simply wait for the reply read coroutine to detect the hangup
and clean up after itself.

This wouldn't be enough though because nbd_receive_reply returns 0
(rather than -EPIPE or similar) when reading from a hung connection.
Fix the return value check in nbd_read_reply_entry.

This fixes qemu-iotests 083.

Reported-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20170314111157.14464-1-pbonzini@redhat.com
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/nbd/client.c b/nbd/client.c
index 3dc2564..a58fb02 100644
--- a/nbd/client.c
+++ b/nbd/client.c
@@ -812,6 +812,6 @@ ssize_t nbd_receive_reply(QIOChannel *ioc, NBDReply *reply)
         LOG("invalid magic (got 0x%" PRIx32 ")", magic);
         return -EINVAL;
     }
-    return 0;
+    return sizeof(buf);
 }