bdrv_reopen_multiple() does not invoke bdrv_reopen_abort() for the element of the reopen queue for which bdrv_reopen_prepare() failed, because it assumes that the prepare function will have rolled back all changes already.
However, bdrv_reopen_prepare() does not do this in every case: It may notice an error after BlockDriver.bdrv_reopen_prepare() succeeded, and it will not invoke BlockDriver.bdrv_reopen_abort() then; and neither will bdrv_reopen_multiple(), as explained above. This is wrong because we must always call .bdrv_reopen_commit() or .bdrv_reopen_abort() after .bdrv_reopen_prepare() has succeeded. Otherwise, the block driver has no chance to undo what it has done in its implementation of .bdrv_reopen_prepare(). To fix this, bdrv_reopen_prepare() has to call .bdrv_reopen_abort() if it wants to return an error after .bdrv_reopen_prepare() has succeeded. Signed-off-by: Max Reitz <mre...@redhat.com> --- block.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/block.c b/block.c index fd67e14dfa..7f5859aa74 100644 --- a/block.c +++ b/block.c @@ -3332,7 +3332,7 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, if (!qobject_is_equal(new, old)) { error_setg(errp, "Cannot change the option '%s'", entry->key); ret = -EINVAL; - goto error; + goto late_error; } } while ((entry = qdict_next(reopen_state->options, entry))); } @@ -3340,7 +3340,7 @@ int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue, ret = bdrv_check_perm(reopen_state->bs, queue, reopen_state->perm, reopen_state->shared_perm, NULL, errp); if (ret < 0) { - goto error; + goto late_error; } ret = 0; @@ -3354,6 +3354,19 @@ error: qobject_unref(orig_reopen_opts); g_free(discard); return ret; + +late_error: + /* drv->bdrv_reopen_prepare() has succeeded, so we need to call + * drv->bdrv_reopen_abort() before signaling an error + * (bdrv_reopen_multiple() will not call bdrv_reopen_abort() when + * the respective bdrv_reopen_prepare() failed) */ + if (drv->bdrv_reopen_abort) { + drv->bdrv_reopen_abort(reopen_state); + } + qemu_opts_del(opts); + qobject_unref(orig_reopen_opts); + g_free(discard); + return ret; } /* -- 2.17.2