From 1644cccea5c71b02b9cf8f78b780e7069a29b189 Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Wed, 17 Nov 2021 11:02:29 -0600 Subject: [PATCH] nbd/server: Don't complain on certain client disconnects 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-stable@nongnu.org Fixes: f148ae7d36 ("nbd/server: Quiesce coroutines on context switch", v6.0.0) Signed-off-by: Eric Blake Reviewed-by: Vladimir Sementsov-Ogievskiy [eblake: defer unrelated typo fixes to later patch] Message-Id: <20211117170230.1128262-2-eblake@redhat.com> Signed-off-by: Eric Blake --- nbd/server.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/nbd/server.c b/nbd/server.c index d9164ee6d0..74ba487094 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)