Re: bcache: unlock new_nodes[i]->write_lock in btree_gc_coalesce

From: Zhiqiang Liu
Date: Mon Apr 20 2020 - 03:48:28 EST




On 2020/4/20 15:10, Coly Li wrote:
> On 2020/4/20 14:55, Zhiqiang Liu wrote:
>> friendly ping...
>>
>
> The patch is good. Just it would be better if the commit log can be more
> accurate and understandable for other readers who are not very familiar
> with bcache code.
>
> Thanks.
>
>
> Coly Li

Thanks for your reply. I will try my best to rewrite the commit log.

Regards.
Zhiqiang Liu.

>
>
>> On 2020/4/15 19:42, Zhiqiang Liu wrote:
>>> From: Zhiqiang Liu <liuzhiqiang26@xxxxxxxxxx>
>>>
>>> coccicheck reports:
>>> drivers/md//bcache/btree.c:1538:1-7:ÂprecedingÂlockÂonÂlineÂ1417
>>>
>>> After obtaining new_nodes[i]->write_lock, we may go to out_nocoalesce
>>> tag without releasing lock. Here, we add a new tag
>>> 'out_unlock_nocoalesce' before out_nocoalesce tag to release
>>> new_nodes[i]->write_lock.
>>>
>>> Fixes: 2a285686c1 ("bcache: btree locking rework")
>>> Signed-off-by: Zhiqiang Liu <liuzhiqiang26@xxxxxxxxxx>
>>> ---
>>> drivers/md/bcache/btree.c | 8 ++++++--
>>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
>>> index fa872df4e770..cad8b0b97e33 100644
>>> --- a/drivers/md/bcache/btree.c
>>> +++ b/drivers/md/bcache/btree.c
>>> @@ -1447,7 +1447,7 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op,
>>> if (__set_blocks(n1, n1->keys + n2->keys,
>>> block_bytes(b->c)) >
>>> btree_blocks(new_nodes[i]))
>>> - goto out_nocoalesce;
>>> + goto out_unlock_nocoalesce;
>>>
>>> keys = n2->keys;
>>> /* Take the key of the node we're getting rid of */
>>> @@ -1476,7 +1476,7 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op,
>>>
>>> if (__bch_keylist_realloc(&keylist,
>>> bkey_u64s(&new_nodes[i]->key)))
>>> - goto out_nocoalesce;
>>> + goto out_unlock_nocoalesce;
>>>
>>> bch_btree_node_write(new_nodes[i], &cl);
>>> bch_keylist_add(&keylist, &new_nodes[i]->key);
>>> @@ -1522,6 +1522,10 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op,
>>> /* Invalidated our iterator */
>>> return -EINTR;
>>>
>>> +out_unlock_nocoalesce:
>>> + for (i = 0; i < nodes; i++)
>>> + mutex_unlock(&new_nodes[i]->write_lock);
>>> +
>>> out_nocoalesce:
>>> closure_sync(&cl);
>>>
>>
>
>