Re: [PATCH] mds: update dentry lease for async create

["Yan, Zheng" <zyan@redhat.com>]

On 3/4/20 10:05 PM, Jeff Layton wrote:
> On Wed, 2020-03-04 at 08:55 -0500, Jeff Layton wrote:
>> On Wed, 2020-03-04 at 21:22 +0800, Yan, Zheng wrote:
>>> Otherwise ceph_d_delete() may return 1 for the dentry, which makes
>>> dput() prune the dentry and clear parent dir's complete flag.
>>>
>>> Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
>>> ---
>>>   fs/ceph/file.c | 3 +++
>>>   1 file changed, 3 insertions(+)
>>>
>>> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
>>> index 53321bf517c2..671b141aedfe 100644
>>> --- a/fs/ceph/file.c
>>> +++ b/fs/ceph/file.c
>>> @@ -480,6 +480,9 @@ static int try_prep_async_create(struct inode *dir, struct dentry *dentry,
>>>   	if (d_in_lookup(dentry)) {
>>>   		if (!__ceph_dir_is_complete(ci))
>>>   			goto no_async;
>>> +		spin_lock(&dentry->d_lock);
>>> +		di->lease_shared_gen = atomic_read(&ci->i_shared_gen);
>>> +		spin_unlock(&dentry->d_lock);
>>>   	} else if (atomic_read(&ci->i_shared_gen) !=
>>>   		   READ_ONCE(di->lease_shared_gen)) {
>>>   		goto no_async;
>>
>> Good catch, merged into testing (with small update to changelog
>> s/mds:/ceph:/)
>>
> 
> One related comment though. This patch implies that lease_shared_gen is
> protected by the d_lock, but it's not held when it's assigned in
> ceph_lookup. Should it be?
> 

we only assign and compare lease_shared_gen, I think it doesn't matter 
if it's protected by d_lock or not