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nbd/client-connection: nbd_co_establish_connection(): return real error

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The only caller of nbd_do_establish_connection() that uses errp is
nbd_open(). The only way to cancel this call is through open_timer
timeout. And for this case, user will be more interested in description
of last failed connect rather than in
"Connection attempt cancelled by other operation".

So, let's change behavior on cancel to return previous failure error if
available.

Do the same for non-blocking failure case. In this case we still don't
have a caller that is interested in errp. But let's be consistent.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy 2021-09-06 22:06:49 +03:00
parent be16b8bf9f
commit 169b9a94ed
1 changed files with 35 additions and 17 deletions
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52
nbd/client-connection.c
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@ -39,16 +39,18 @@ struct NBDClientConnection {
QemuMutex mutex;
/*
* @sioc and @err represent a connection attempt. While running
* is true, they are only used by the connection thread, and mutex
* locking is not needed. Once the thread finishes,
* nbd_co_establish_connection then steals these pointers while
* under the mutex.
*/
NBDExportInfo updated_info;
/*
* @sioc represents a successful result. While thread is running, @sioc is
* used only by thread and not protected by mutex. When thread is not
* running, @sioc is stolen by nbd_co_establish_connection() under mutex.
*/
QIOChannelSocket *sioc;
QIOChannel *ioc;
/*
* @err represents previous attempt. It may be copied by
* nbd_co_establish_connection() when it reports failure.
*/
Error *err;
/* All further fields are accessed only under mutex */
@ -170,18 +172,18 @@ static void *connect_thread_func(void *opaque)
qemu_mutex_lock(&conn->mutex);
while (!conn->detached) {
Error *local_err = NULL;
assert(!conn->sioc);
conn->sioc = qio_channel_socket_new();
qemu_mutex_unlock(&conn->mutex);
error_free(conn->err);
conn->err = NULL;
conn->updated_info = conn->initial_info;
ret = nbd_connect(conn->sioc, conn->saddr,
conn->do_negotiation ? &conn->updated_info : NULL,
conn->tlscreds, &conn->ioc, &conn->err);
conn->tlscreds, &conn->ioc, &local_err);
/*
* conn->updated_info will finally be returned to the user. Clear the
@ -194,6 +196,10 @@ static void *connect_thread_func(void *opaque)
qemu_mutex_lock(&conn->mutex);
error_free(conn->err);
conn->err = NULL;
error_propagate(&conn->err, local_err);
if (ret < 0) {
object_unref(OBJECT(conn->sioc));
conn->sioc = NULL;
@ -311,14 +317,17 @@ nbd_co_establish_connection(NBDClientConnection *conn, NBDExportInfo *info,
}
conn->running = true;
error_free(conn->err);
conn->err = NULL;
qemu_thread_create(&thread, "nbd-connect",
connect_thread_func, conn, QEMU_THREAD_DETACHED);
}
if (!blocking) {
error_setg(errp, "No connection at the moment");
if (conn->err) {
error_propagate(errp, error_copy(conn->err));
} else {
error_setg(errp, "No connection at the moment");
}
return NULL;
}
@ -339,14 +348,23 @@ nbd_co_establish_connection(NBDClientConnection *conn, NBDExportInfo *info,
* attempt as failed, but leave the connection thread running,
* to reuse it for the next connection attempt.
*/
error_setg(errp, "Connection attempt cancelled by other operation");
if (conn->err) {
error_propagate(errp, error_copy(conn->err));
} else {
error_setg(errp,
"Connection attempt cancelled by other operation");
}
return NULL;
} else {
error_propagate(errp, conn->err);
conn->err = NULL;
if (!conn->sioc) {
/* Thread finished. There must be either error or sioc */
assert(!conn->err != !conn->sioc);
if (conn->err) {
error_propagate(errp, error_copy(conn->err));
return NULL;
}
if (conn->do_negotiation) {
memcpy(info, &conn->updated_info, sizeof(*info));
if (conn->ioc) {