@@ -2082,11 +2082,20 @@ static void bdrv_child_abort_perm_update(BdrvChild *c)
int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
Error **errp)
{
+ Error *local_err = NULL;
int ret;
+ bool loosen_restrictions;
- ret = bdrv_child_check_perm(c, NULL, perm, shared, NULL, NULL, errp);
+ ret = bdrv_child_check_perm(c, NULL, perm, shared, NULL,
+ &loosen_restrictions, &local_err);
if (ret < 0) {
bdrv_child_abort_perm_update(c);
+ if (loosen_restrictions) {
+ warn_reportf_err(local_err, "Failed to loosen restrictions: ");
+ ret = 0;
+ } else {
+ error_propagate(errp, local_err);
+ }
return ret;
}
@@ -2269,10 +2278,20 @@ static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs)
/* Update permissions for old node. This is guaranteed to succeed
* because we're just taking a parent away, so we're loosening
* restrictions. */
+ bool loosen_restrictions;
+ Error *local_err = NULL;
+ int ret;
+
bdrv_get_cumulative_perm(old_bs, &perm, &shared_perm);
- bdrv_check_perm(old_bs, NULL, perm, shared_perm, NULL,
- NULL, &error_abort);
- bdrv_set_perm(old_bs, perm, shared_perm);
+ ret = bdrv_check_perm(old_bs, NULL, perm, shared_perm, NULL,
+ &loosen_restrictions, &local_err);
+ assert(loosen_restrictions == true);
+ if (ret < 0) {
+ warn_reportf_err(local_err, "Failed to loosen restrictions: ");
+ bdrv_abort_perm_update(old_bs);
+ } else {
+ bdrv_set_perm(old_bs, perm, shared_perm);
+ }
}
}
@@ -5316,7 +5335,9 @@ static bool bdrv_has_bds_parent(BlockDriverState *bs, bool only_active)
static int bdrv_inactivate_recurse(BlockDriverState *bs)
{
BdrvChild *child, *parent;
+ bool loosen_restrictions;
uint64_t perm, shared_perm;
+ Error *local_err = NULL;
int ret;
if (!bs->drv) {
@@ -5352,8 +5373,15 @@ static int bdrv_inactivate_recurse(BlockDriverState *bs)
/* Update permissions, they may differ for inactive nodes */
bdrv_get_cumulative_perm(bs, &perm, &shared_perm);
- bdrv_check_perm(bs, NULL, perm, shared_perm, NULL, NULL, &error_abort);
- bdrv_set_perm(bs, perm, shared_perm);
+ ret = bdrv_check_perm(bs, NULL, perm, shared_perm, NULL,
+ &loosen_restrictions, &local_err);
+ assert(loosen_restrictions == true);
+ if (ret < 0) {
+ warn_reportf_err(local_err, "Failed to loosen restrictions: ");
+ bdrv_abort_perm_update(bs);
+ } else {
+ bdrv_set_perm(bs, perm, shared_perm);
+ }
/* Recursively inactivate children */
We generally assume that loosening permission restrictions can never fail. We have seen in the past that this assumption is wrong. This has led to crashes because we generally pass &error_abort when loosening permissions. However, a failure in such a case should actually be handled in quite the opposite way: It is very much not fatal, so qemu may report it, but still consider the operation successful. The only realistic problem is that qemu may then retain permissions and thus locks on images it actually does not require. But again, that is not fatal. To implement this behavior, we make all functions that change permissions and that pass &error_abort to the initiating function (bdrv_check_perm() or bdrv_child_check_perm()) evaluate the @loosen_restrictions value introduced in the previous patch. If it is true and an error did occur, we abort the permission update, report the error, and report success to the caller. bdrv_child_try_set_perm() itself does not pass &error_abort, but it is the only public function to change permissions. As such, callers may pass &error_abort to it, expecting dropping permission restrictions to never fail. Signed-off-by: Max Reitz <mreitz@redhat.com> --- block.c | 40 ++++++++++++++++++++++++++++++++++------ 1 file changed, 34 insertions(+), 6 deletions(-)