Re: [PATCH] ceph: fix NULL pointer dereference for req->r_session

[Xiubo Li <xiubli@redhat.com>]

On 07/11/2022 22:55, Ilya Dryomov wrote:
> On Thu, Oct 27, 2022 at 11:12 AM <xiubli@redhat.com> wrote:
>> From: Xiubo Li <xiubli@redhat.com>
>>
>> The request's r_session maybe changed when it was forwarded or
>> resent.
>>
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Xiubo Li <xiubli@redhat.com>
>> ---
>>   fs/ceph/caps.c | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
>> index 894adfb4a092..d34ac716d7fe 100644
>> --- a/fs/ceph/caps.c
>> +++ b/fs/ceph/caps.c
>> @@ -2341,6 +2341,7 @@ static int flush_mdlog_and_wait_inode_unsafe_requests(struct inode *inode)
>>                          goto out;
>>                  }
>>
>> +               mutex_lock(&mdsc->mutex);
> Hi Xiubo,
>
> A few lines above, there is the following comment:
>
>          /*
>           * The mdsc->max_sessions is unlikely to be changed
>           * mostly, here we will retry it by reallocating the
>           * sessions array memory to get rid of the mdsc->mutex
>           * lock.
>           */
>
> Does retry label and gotos still make sense if mdsc->mutex is
> introduced?  Would it make sense to move it up and get rid of
> retry code?

I'm okay to remove the label since we will introduce the mdsc->mutex.

Thanks!

- Xiubo

> Thanks,
>
>                  Ilya
>