When a client disconnects abruptly, but did not have any pending
requests (for example, when using nbdsh without calling h.shutdown),
we used to output the following message:
$ qemu-nbd -f raw file
$ nbdsh -u 'nbd://localhost:10809' -c 'h.trim(1,0)'
qemu-nbd: Disconnect client, due to: Failed to read request: Unexpected
end-of-file before all bytes were read
Then in commit f148ae7, we refactored nbd_receive_request() to use
nbd_read_eof(); when this returns 0, we regressed into tracing
uninitialized memory (if tracing is enabled) and reporting a
less-specific:
qemu-nbd: Disconnect client, due to: Request handling failed in intermediate
state
Note that with Unix sockets, we have yet another error message,
unchanged by the 6.0 regression:
$ qemu-nbd -k /tmp/sock -f raw file
$ nbdsh -u 'nbd+unix:///?socket=/tmp/sock' -c 'h.trim(1,0)'
qemu-nbd: Disconnect client, due to: Failed to send reply: Unable to write to
socket: Broken pipe
But in all cases, the error message goes away if the client performs a
soft shutdown by using NBD_CMD_DISC, rather than a hard shutdown by
abrupt disconnect:
$ nbdsh -u 'nbd://localhost:10809' -c 'h.trim(1,0)' -c 'h.shutdown()'
This patch fixes things to avoid uninitialized memory, and in general
avoids warning about a client that does a hard shutdown when not in
the middle of a packet. A client that aborts mid-request, or which
does not read the full server's reply, can still result in warnings,
but those are indeed much more unusual situations.
CC: qemu-sta...@nongnu.org
Fixes: f148ae7d36 (nbd/server: Quiesce coroutines on context switch)
Signed-off-by: Eric Blake <ebl...@redhat.com>
---
nbd/server.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/nbd/server.c b/nbd/server.c
index d9164ee6d0da..85877f630533 100644
--- a/nbd/server.c
+++ b/nbd/server.c
@@ -1418,6 +1418,9 @@ static int nbd_receive_request(NBDClient *client,
NBDRequest *request,
if (ret < 0) {
return ret;
}
+ if (ret == 0) {
+ return -EIO;
+ }
/* Request
[ 0 .. 3] magic (NBD_REQUEST_MAGIC)
@@ -2285,7 +2288,7 @@ static int nbd_co_receive_request(NBDRequestData *req,
NBDRequest *request,
assert(client->recv_coroutine == qemu_coroutine_self());
ret = nbd_receive_request(client, request, errp);
if (ret < 0) {
- return ret;
+ return ret;
}
trace_nbd_co_receive_request_decode_type(request->handle, request->type,
@@ -2662,7 +2665,7 @@ static coroutine_fn void nbd_trip(void *opaque)
}
if (ret < 0) {
- /* It wans't -EIO, so, according to nbd_co_receive_request()
+ /* It wasn't -EIO, so, according to nbd_co_receive_request()
* semantics, we should return the error to the client. */
Error *export_err = local_err;
--
2.33.1
