On 15/05/2020 11:24, Bo YU wrote:
> Hi,
> On Fri, May 15, 2020 at 5:03 PM Johannes Thumshirn
> <[email protected]> wrote:
>>
>> On 15/05/2020 04:17, Bo YU wrote:
>>> It adds spin_lock() in add_block_entry() but out path does not unlock
>>> it.
>>
>> Which call path doesn't unlock it? There is an out_unlock label with a
>> spin_unlock() right above your insert. So either coverity messed something
>> up or the call path that needs the unlock has to jump to out_unlock instead
>> of out.
> This is out label without unlocking it. It will be offered spin_lock
> in add_block_entry()
> for be. But here I was worried about that unlock it in if() whether it
> is right or not.
>
No add_block_entry() returns with the ref_verify_lock held on success only:
static struct block_entry *add_block_entry(struct btrfs_fs_info *fs_info,
u64 bytenr, u64 len,
u64 root_objectid)
{
struct block_entry *be = NULL, *exist;
struct root_entry *re = NULL;
re = kzalloc(sizeof(struct root_entry), GFP_KERNEL);
be = kzalloc(sizeof(struct block_entry), GFP_KERNEL);
if (!be || !re) {
kfree(re);
kfree(be);
return ERR_PTR(-ENOMEM);
}
be->bytenr = bytenr;
be->len = len;
re->root_objectid = root_objectid;
re->num_refs = 0;
spin_lock(&fs_info->ref_verify_lock);
[...]
While the code caller checks for an error:
if (action == BTRFS_ADD_DELAYED_EXTENT) {
/*
* For subvol_create we'll just pass in whatever the parent root
* is and the new root objectid, so let's not treat the passed
* in root as if it really has a ref for this bytenr.
*/
be = add_block_entry(fs_info, bytenr, num_bytes, ref_root);
if (IS_ERR(be)) {
kfree(ref);
kfree(ra);
ret = PTR_ERR(be);
goto out;
}
So if add_block_entry returns -ENOMEM it didn't take the lock and thus no unlock
is needed.
Or did I miss something?
