nbd patches for 2019-09-24

- Improved error message for plaintext client of encrypted server
 - Fix various assertions when -object iothread is in use
 - Silence a Coverity error for use-after-free on error path
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Merge remote-tracking branch 'remotes/ericb/tags/pull-nbd-2019-09-24-v2' into staging

nbd patches for 2019-09-24

- Improved error message for plaintext client of encrypted server
- Fix various assertions when -object iothread is in use
- Silence a Coverity error for use-after-free on error path

# gpg: Signature made Wed 25 Sep 2019 14:35:52 BST
# gpg:                using RSA key 71C2CC22B1C4602927D2F3AAA7A16B4A2527436A
# gpg: Good signature from "Eric Blake <eblake@redhat.com>" [full]
# gpg:                 aka "Eric Blake (Free Software Programmer) <ebb9@byu.net>" [full]
# gpg:                 aka "[jpeg image of size 6874]" [full]
# Primary key fingerprint: 71C2 CC22 B1C4 6029 27D2  F3AA A7A1 6B4A 2527 436A

* remotes/ericb/tags/pull-nbd-2019-09-24-v2:
  util/qemu-sockets: fix keep_alive handling in inet_connect_saddr
  tests: Use iothreads during iotest 223
  nbd: Grab aio context lock in more places
  nbd/server: attach client channel to the export's AioContext
  nbd/client: Add hint when TLS is missing

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

blockdev-nbd.c

@@ -151,6 +151,7 @@ void qmp_nbd_server_add(const char *device, bool has_name, const char *name,
     BlockBackend *on_eject_blk;
     NBDExport *exp;
     int64_t len;
+    AioContext *aio_context;
 
     if (!nbd_server) {
         error_setg(errp, "NBD server not running");
@@ -173,11 +174,13 @@ void qmp_nbd_server_add(const char *device, bool has_name, const char *name,
         return;
     }
 
+    aio_context = bdrv_get_aio_context(bs);
+    aio_context_acquire(aio_context);
     len = bdrv_getlength(bs);
     if (len < 0) {
         error_setg_errno(errp, -len,
                          "Failed to determine the NBD export's length");
-        return;
+        goto out;
     }
 
     if (!has_writable) {
@@ -190,13 +193,16 @@ void qmp_nbd_server_add(const char *device, bool has_name, const char *name,
     exp = nbd_export_new(bs, 0, len, name, NULL, bitmap, !writable, !writable,
                          NULL, false, on_eject_blk, errp);
     if (!exp) {
-        return;
+        goto out;
     }
 
     /* The list of named exports has a strong reference to this export now and
      * our only way of accessing it is through nbd_export_find(), so we can drop
      * the strong reference that is @exp. */
     nbd_export_put(exp);
+
+ out:
+    aio_context_release(aio_context);
 }
 
 void qmp_nbd_server_remove(const char *name,
@@ -204,6 +210,7 @@ void qmp_nbd_server_remove(const char *name,
                            Error **errp)
 {
     NBDExport *exp;
+    AioContext *aio_context;
 
     if (!nbd_server) {
         error_setg(errp, "NBD server not running");
@@ -220,7 +227,10 @@ void qmp_nbd_server_remove(const char *name,
         mode = NBD_SERVER_REMOVE_MODE_SAFE;
     }
 
+    aio_context = nbd_export_aio_context(exp);
+    aio_context_acquire(aio_context);
     nbd_export_remove(exp, mode, errp);
+    aio_context_release(aio_context);
 }
 
 void qmp_nbd_server_stop(Error **errp)

include/block/nbd.h

@@ -340,6 +340,7 @@ void nbd_export_put(NBDExport *exp);
 
 BlockBackend *nbd_export_get_blockdev(NBDExport *exp);
 
+AioContext *nbd_export_aio_context(NBDExport *exp);
 NBDExport *nbd_export_find(const char *name);
 void nbd_export_close_all(void);
 

nbd/client.c

@@ -204,6 +204,7 @@ static int nbd_handle_reply_err(QIOChannel *ioc, NBDOptionReply *reply,
     case NBD_REP_ERR_TLS_REQD:
         error_setg(errp, "TLS negotiation required before option %" PRIu32
                    " (%s)", reply->option, nbd_opt_lookup(reply->option));
+        error_append_hint(errp, "Did you forget a valid tls-creds?\n");
         break;
 
     case NBD_REP_ERR_UNKNOWN:

nbd/server.c

@@ -1297,6 +1297,11 @@ static coroutine_fn int nbd_negotiate(NBDClient *client, Error **errp)
         return ret;
     }
 
+    /* Attach the channel to the same AioContext as the export */
+    if (client->exp && client->exp->ctx) {
+        qio_channel_attach_aio_context(client->ioc, client->exp->ctx);
+    }
+
     assert(!client->optlen);
     trace_nbd_negotiate_success();
 
@@ -1456,7 +1461,12 @@ static void blk_aio_detach(void *opaque)
 static void nbd_eject_notifier(Notifier *n, void *data)
 {
     NBDExport *exp = container_of(n, NBDExport, eject_notifier);
+    AioContext *aio_context;
+
+    aio_context = exp->ctx;
+    aio_context_acquire(aio_context);
     nbd_export_close(exp);
+    aio_context_release(aio_context);
 }
 
 NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
@@ -1475,12 +1485,11 @@ NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
      * NBD exports are used for non-shared storage migration.  Make sure
      * that BDRV_O_INACTIVE is cleared and the image is ready for write
      * access since the export could be available before migration handover.
+     * ctx was acquired in the caller.
      */
     assert(name);
     ctx = bdrv_get_aio_context(bs);
-    aio_context_acquire(ctx);
     bdrv_invalidate_cache(bs, NULL);
-    aio_context_release(ctx);
 
     /* Don't allow resize while the NBD server is running, otherwise we don't
      * care what happens with the node. */
@@ -1488,7 +1497,7 @@ NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
     if (!readonly) {
         perm |= BLK_PERM_WRITE;
     }
-    blk = blk_new(bdrv_get_aio_context(bs), perm,
+    blk = blk_new(ctx, perm,
                   BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED |
                   BLK_PERM_WRITE | BLK_PERM_GRAPH_MOD);
     ret = blk_insert_bs(blk, bs, errp);
@@ -1555,7 +1564,7 @@ NBDExport *nbd_export_new(BlockDriverState *bs, uint64_t dev_offset,
     }
 
     exp->close = close;
-    exp->ctx = blk_get_aio_context(blk);
+    exp->ctx = ctx;
     blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
 
     if (on_eject_blk) {
@@ -1588,6 +1597,12 @@ NBDExport *nbd_export_find(const char *name)
     return NULL;
 }
 
+AioContext *
+nbd_export_aio_context(NBDExport *exp)
+{
+    return exp->ctx;
+}
+
 void nbd_export_close(NBDExport *exp)
 {
     NBDClient *client, *next;
@@ -1682,9 +1697,13 @@ BlockBackend *nbd_export_get_blockdev(NBDExport *exp)
 void nbd_export_close_all(void)
 {
     NBDExport *exp, *next;
+    AioContext *aio_context;
 
     QTAILQ_FOREACH_SAFE(exp, &exports, next, next) {
+        aio_context = exp->ctx;
+        aio_context_acquire(aio_context);
         nbd_export_close(exp);
+        aio_context_release(aio_context);
     }
 }
 

tests/qemu-iotests/223

@@ -2,7 +2,7 @@
 #
 # Test reading dirty bitmap over NBD
 #
-# Copyright (C) 2018 Red Hat, Inc.
+# Copyright (C) 2018-2019 Red Hat, Inc.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -109,7 +109,7 @@ echo
 echo "=== End dirty bitmaps, and start serving image over NBD ==="
 echo
 
-_launch_qemu 2> >(_filter_nbd)
+_launch_qemu -object iothread,id=io0 2> >(_filter_nbd)
 
 # Intentionally provoke some errors as well, to check error handling
 silent=
@@ -117,6 +117,8 @@ _send_qemu_cmd $QEMU_HANDLE '{"execute":"qmp_capabilities"}' "return"
 _send_qemu_cmd $QEMU_HANDLE '{"execute":"blockdev-add",
   "arguments":{"driver":"qcow2", "node-name":"n",
     "file":{"driver":"file", "filename":"'"$TEST_IMG"'"}}}' "return"
+_send_qemu_cmd $QEMU_HANDLE '{"execute":"x-blockdev-set-iothread",
+  "arguments":{"node-name":"n", "iothread":"io0"}}' "return"
 _send_qemu_cmd $QEMU_HANDLE '{"execute":"block-dirty-bitmap-disable",
   "arguments":{"node":"n", "name":"b"}}' "return"
 _send_qemu_cmd $QEMU_HANDLE '{"execute":"nbd-server-add",

tests/qemu-iotests/223.out

@@ -27,6 +27,7 @@ wrote 2097152/2097152 bytes at offset 2097152
 {"return": {}}
 {"return": {}}
 {"return": {}}
+{"return": {}}
 {"error": {"class": "GenericError", "desc": "NBD server not running"}}
 {"return": {}}
 {"error": {"class": "GenericError", "desc": "NBD server already running"}}

tests/qemu-iotests/233.out

@@ -21,8 +21,10 @@ server reported: TLS not configured
 
 == check plain client to TLS server fails ==
 qemu-img: Could not open 'nbd://localhost:PORT': TLS negotiation required before option 7 (go)
+Did you forget a valid tls-creds?
 server reported: Option 0x7 not permitted before TLS
 qemu-nbd: TLS negotiation required before option 3 (list)
+Did you forget a valid tls-creds?
 server reported: Option 0x3 not permitted before TLS
 
 == check TLS works ==

util/qemu-sockets.c

@@ -461,12 +461,13 @@ int inet_connect_saddr(InetSocketAddress *saddr, Error **errp)
         }
     }
 
+    freeaddrinfo(res);
+
     if (sock < 0) {
         error_propagate(errp, local_err);
+        return sock;
     }
 
-    freeaddrinfo(res);
-
     if (saddr->keep_alive) {
         int val = 1;
         int ret = qemu_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,