We have to perform an active commit whenever the top node has a parent
that has taken the WRITE permission on it.
Signed-off-by: Max Reitz <mre...@redhat.com>
---
blockdev.c | 24 +++++++++++++++++++++---
1 file changed, 21 insertions(+), 3 deletions(-)
diff --git a/blockdev.c b/blockdev.c
index a464cabf9e..5370f3b738 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3294,6 +3294,7 @@ void qmp_block_commit(bool has_job_id, const char
*job_id, const char *device,
*/
BlockdevOnError on_error = BLOCKDEV_ON_ERROR_REPORT;
int job_flags = JOB_DEFAULT;
+ uint64_t top_perm, top_shared;
if (!has_speed) {
speed = 0;
@@ -3406,14 +3407,31 @@ void qmp_block_commit(bool has_job_id, const char
*job_id, const char *device,
goto out;
}
- if (top_bs == bs) {
+ /*
+ * Active commit is required if and only if someone has taken a
+ * WRITE permission on the top node. Historically, we have always
+ * used active commit for top nodes, so continue that practice.
+ * (Active commit is never really wrong.)
+ */
+ bdrv_get_cumulative_perm(top_bs, &top_perm, &top_shared);
+ if (top_perm & BLK_PERM_WRITE ||
+ bdrv_skip_rw_filters(top_bs) == bdrv_skip_rw_filters(bs))
+ {
if (has_backing_file) {
error_setg(errp, "'backing-file' specified,"
" but 'top' is the active layer");
goto out;
}
- commit_active_start(has_job_id ? job_id : NULL, bs, base_bs,
- job_flags, speed, on_error,
+ if (!has_job_id) {
+ /*
+ * Emulate here what block_job_create() does, because it
+ * is possible that @bs != @top_bs (the block job should
+ * be named after @bs, even if @top_bs is the actual
+ * source)
+ */
+ job_id = bdrv_get_device_name(bs);
+ }
+ commit_active_start(job_id, top_bs, base_bs, job_flags, speed,
on_error,
filter_node_name, NULL, NULL, false, &local_err);
} else {
BlockDriverState *overlay_bs = bdrv_find_overlay(bs, top_bs);
--
2.21.0
