[RFC v5 113/126] qcow: introduce ERRP_AUTO_PROPAGATE

[Vladimir Sementsov-Ogievskiy]

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

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

This commit (together with its neighbors) was generated by

for f in $(git grep -l errp \*.[ch]); do \
    spatch --sp-file scripts/coccinelle/auto-propagated-errp.cocci \
    --macro-file scripts/cocci-macro-file.h --in-place --no-show-diff $f; \
done;

then fix a bit of compilation problems: coccinelle for some reason
leaves several
f() {
    ...
    goto out;
    ...
    out:
}
patterns, with "out:" at function end.

then
./python/commit-per-subsystem.py MAINTAINERS "$(< auto-msg)"

(auto-msg was a file with this commit message)

Still, for backporting it may be more comfortable to use only the first
command and then do one huge commit.

Reported-by: Kevin Wolf <address@hidden>
Reported-by: Greg Kurz <address@hidden>
Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
---
 block/qcow.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/block/qcow.c b/block/qcow.c
index 5bdf72ba33..c58d3e36be 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -117,11 +117,11 @@ static QemuOptsList qcow_runtime_opts = {
 static int qcow_open(BlockDriverState *bs, QDict *options, int flags,
                      Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     BDRVQcowState *s = bs->opaque;
     unsigned int len, i, shift;
     int ret;
     QCowHeader header;
-    Error *local_err = NULL;
     QCryptoBlockOpenOptions *crypto_opts = NULL;
     unsigned int cflags = 0;
     QDict *encryptopts = NULL;
@@ -314,9 +314,8 @@ static int qcow_open(BlockDriverState *bs, QDict *options, 
int flags,
     error_setg(&s->migration_blocker, "The qcow format used by node '%s' "
                "does not support live migration",
                bdrv_get_device_or_node_name(bs));
-    ret = migrate_add_blocker(s->migration_blocker, &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+    ret = migrate_add_blocker(s->migration_blocker, errp);
+    if (*errp) {
         error_free(s->migration_blocker);
         goto fail;
     }
@@ -942,12 +941,12 @@ exit:
 static int coroutine_fn qcow_co_create_opts(const char *filename,
                                             QemuOpts *opts, Error **errp)
 {
+    ERRP_AUTO_PROPAGATE();
     BlockdevCreateOptions *create_options = NULL;
     BlockDriverState *bs = NULL;
     QDict *qdict;
     Visitor *v;
     const char *val;
-    Error *local_err = NULL;
     int ret;
 
     static const QDictRenames opt_renames[] = {
@@ -977,9 +976,8 @@ static int coroutine_fn qcow_co_create_opts(const char 
*filename,
     }
 
     /* Create and open the file (protocol layer) */
-    ret = bdrv_create_file(filename, opts, &local_err);
+    ret = bdrv_create_file(filename, opts, errp);
     if (ret < 0) {
-        error_propagate(errp, local_err);
         goto fail;
     }
 
@@ -1000,11 +998,10 @@ static int coroutine_fn qcow_co_create_opts(const char 
*filename,
         goto fail;
     }
 
-    visit_type_BlockdevCreateOptions(v, NULL, &create_options, &local_err);
+    visit_type_BlockdevCreateOptions(v, NULL, &create_options, errp);
     visit_free(v);
 
-    if (local_err) {
-        error_propagate(errp, local_err);
+    if (*errp) {
         ret = -EINVAL;
         goto fail;
     }
-- 
2.21.0