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block: Include details on permission errors in message

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Instead of just telling that there was some conflict, we can be specific
and tell which permissions were in conflict and which way the conflict
is.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Kevin Wolf 2017-01-16 18:26:20 +01:00
parent b541155587
commit d083319fe0
1 changed files with 56 additions and 11 deletions
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67
block.c
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@ -1462,6 +1462,43 @@ static void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
*shared_perm = cumulative_shared_perms;
}
static char *bdrv_child_user_desc(BdrvChild *c)
{
if (c->role->get_parent_desc) {
return c->role->get_parent_desc(c);
}
return g_strdup("another user");
}
static char *bdrv_perm_names(uint64_t perm)
{
struct perm_name {
uint64_t perm;
const char *name;
} permissions[] = {
{ BLK_PERM_CONSISTENT_READ, "consistent read" },
{ BLK_PERM_WRITE, "write" },
{ BLK_PERM_WRITE_UNCHANGED, "write unchanged" },
{ BLK_PERM_RESIZE, "resize" },
{ BLK_PERM_GRAPH_MOD, "change children" },
{ 0, NULL }
};
char *result = g_strdup("");
struct perm_name *p;
for (p = permissions; p->name; p++) {
if (perm & p->perm) {
char *old = result;
result = g_strdup_printf("%s%s%s", old, *old ? ", " : "", p->name);
g_free(old);
}
}
return result;
}
/*
* Checks whether a new reference to @bs can be added if the new user requires
* @new_used_perm/@new_shared_perm as its permissions. If @ignore_child is set,
@ -1486,17 +1523,25 @@ static int bdrv_check_update_perm(BlockDriverState *bs, uint64_t new_used_perm,
continue;
}
if ((new_used_perm & c->shared_perm) != new_used_perm ||
(c->perm & new_shared_perm) != c->perm)
{
const char *user = NULL;
if (c->role->get_name) {
user = c->role->get_name(c);
if (user && !*user) {
user = NULL;
}
}
error_setg(errp, "Conflicts with %s", user ?: "another operation");
if ((new_used_perm & c->shared_perm) != new_used_perm) {
char *user = bdrv_child_user_desc(c);
char *perm_names = bdrv_perm_names(new_used_perm & ~c->shared_perm);
error_setg(errp, "Conflicts with use by %s as '%s', which does not "
"allow '%s' on %s",
user, c->name, perm_names, bdrv_get_node_name(c->bs));
g_free(user);
g_free(perm_names);
return -EPERM;
}
if ((c->perm & new_shared_perm) != c->perm) {
char *user = bdrv_child_user_desc(c);
char *perm_names = bdrv_perm_names(c->perm & ~new_shared_perm);
error_setg(errp, "Conflicts with use by %s as '%s', which uses "
"'%s' on %s",
user, c->name, perm_names, bdrv_get_node_name(c->bs));
g_free(user);
g_free(perm_names);
return -EPERM;
}