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block: Simplify bdrv_append_temp_snapshot() logic 

Noticed while checking Coccinelle results. Naming a label 'out:'
when it is only used on error paths is weird.  Also, we had some
dead stores to 'ret'.  Meanwhile we know that snapshot_options
is NULL on success and that QDECREF(NULL) is safe.  So merge the
two exit paths into one by careful control over bs_snapshot.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20170427215821.19397-8-eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
This commit is contained in:
Eric Blake 2017-04-27 16:58:18 -05:00 committed by Markus Armbruster
parent 46f5ac205a
commit ff6ed7141d
1 changed files with 7 additions and 10 deletions
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17
block.c
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@ -2195,7 +2195,7 @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
char *tmp_filename = g_malloc0(PATH_MAX + 1); char *tmp_filename = g_malloc0(PATH_MAX + 1);
int64_t total_size; int64_t total_size;
QemuOpts *opts = NULL; QemuOpts *opts = NULL;
BlockDriverState *bs_snapshot; BlockDriverState *bs_snapshot = NULL;
Error *local_err = NULL; Error *local_err = NULL;
int ret; int ret;
@ -2235,28 +2235,25 @@ static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
bs_snapshot = bdrv_open(NULL, NULL, snapshot_options, flags, errp); bs_snapshot = bdrv_open(NULL, NULL, snapshot_options, flags, errp);
snapshot_options = NULL; snapshot_options = NULL;
if (!bs_snapshot) { if (!bs_snapshot) {
ret = -EINVAL;
goto out; goto out;
} }
/* bdrv_append() consumes a strong reference to bs_snapshot (i.e. it will /* bdrv_append() consumes a strong reference to bs_snapshot
* call bdrv_unref() on it), so in order to be able to return one, we have * (i.e. it will call bdrv_unref() on it) even on error, so in
* to increase bs_snapshot's refcount here */ * order to be able to return one, we have to increase
* bs_snapshot's refcount here */
bdrv_ref(bs_snapshot); bdrv_ref(bs_snapshot);
bdrv_append(bs_snapshot, bs, &local_err); bdrv_append(bs_snapshot, bs, &local_err);
if (local_err) { if (local_err) {
error_propagate(errp, local_err); error_propagate(errp, local_err);
ret = -EINVAL; bs_snapshot = NULL;
goto out; goto out;
} }
g_free(tmp_filename);
return bs_snapshot;
out: out:
QDECREF(snapshot_options); QDECREF(snapshot_options);
g_free(tmp_filename); g_free(tmp_filename);
return NULL; return bs_snapshot;
} }
/* /*