nbd: Use ERRP_GUARD()

If we want to check error after errp-function call, we need to
introduce local_err and then propagate it to errp. Instead, use
the ERRP_GUARD() macro, benefits are:
1. No need of explicit error_propagate call
2. No need of explicit local_err variable: use errp directly
3. ERRP_GUARD() leaves errp as is if it's not NULL or
   &error_fatal, this means that we don't break error_abort
   (we'll abort on error_set, not on error_propagate)

If we want to add some info to errp (by error_prepend() or
error_append_hint()), we must use the ERRP_GUARD() macro.
Otherwise, this info will not be added when errp == &error_fatal
(the program will exit prior to the error_append_hint() or
error_prepend() call).  Fix several such cases, e.g. in nbd_read().

This commit is generated by command

    sed -n '/^Network Block Device (NBD)$/,/^$/{s/^F: //p}' \
        MAINTAINERS | \
    xargs git ls-files | grep '\.[hc]$' | \
    xargs spatch \
        --sp-file scripts/coccinelle/errp-guard.cocci \
        --macro-file scripts/cocci-macro-file.h \
        --in-place --no-show-diff --max-width 80

Reported-by: Kevin Wolf <kwolf@redhat.com>
Reported-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Commit message tweaked]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200707165037.1026246-8-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[ERRP_AUTO_PROPAGATE() renamed to ERRP_GUARD(), and
auto-propagated-errp.cocci to errp-guard.cocci.  Commit message
tweaked again.]

1 files changed, 1 insertions, 0 deletions

diff --git a/include/block/nbd.h b/include/block/nbd.h
index 20363280ae..9bc3bfaeec 100644
--- a/include/block/nbd.h
+++ b/include/block/nbd.h
@@ -361,6 +361,7 @@ void nbd_server_start_options(NbdServerOptions *arg, Error **errp);
 static inline int nbd_read(QIOChannel *ioc, void *buffer, size_t size,
                            const char *desc, Error **errp)
 {
+    ERRP_GUARD();
     int ret = qio_channel_read_all(ioc, buffer, size, errp) < 0 ? -EIO : 0;
 
     if (ret < 0) {