Re: [PATCH 2/3] NFSD: Increase the reference of lockowner when coping file_lock

[Kinglong Mee <kinglongmee@gmail.com>]

On 8/9/2014 19:08, Jeff Layton wrote:
> On Wed, 06 Aug 2014 21:35:40 +0800
> Kinglong Mee <kinglongmee@gmail.com> wrote:
> 
>> Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
>> ---
>>  fs/nfsd/nfs4state.c | 33 +++++++++++++++++++++++++++++++--
>>  1 file changed, 31 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>> index 24168ae..07e4b5c 100644
>> --- a/fs/nfsd/nfs4state.c
>> +++ b/fs/nfsd/nfs4state.c
>> @@ -4867,6 +4867,29 @@ nfs4_transform_lock_offset(struct file_lock *lock)
>>  		lock->fl_end = OFFSET_MAX;
>>  }
>>  
>> +static inline struct nfs4_lockowner *get_lockowner(struct nfs4_lockowner *lo)
>> +{
>> +	atomic_inc(&lo->lo_owner.so_count);
>> +	return lo;
>> +}
>> +
>> +static void nfsd4_fl_copy_lock(struct file_lock *dst, struct file_lock *src)
>> +{
>> +	struct nfs4_lockowner *lo = (struct nfs4_lockowner *) src->fl_owner;
>> +	get_lockowner(lo);
>> +}
>> +
>> +static void nfsd4_fl_release_lock(struct file_lock *fl)
>> +{
>> +	struct nfs4_lockowner *lo = (struct nfs4_lockowner *) fl->fl_owner;
>> +	nfs4_put_stateowner(&lo->lo_owner);
>> +}
>> +
>> +static const struct file_lock_operations nfsd4_fl_lock_ops = {
>> +	.fl_copy_lock = nfsd4_fl_copy_lock,
>> +	.fl_release_private = nfsd4_fl_release_lock,
>> +};
>> +
>>  static inline void
>>  nfs4_set_lock_denied(struct file_lock *fl, struct nfsd4_lock_denied *deny)
>>  {
>> @@ -5233,10 +5256,12 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>>  		status = nfserr_openmode;
>>  		goto out;
>>  	}
>> -	file_lock->fl_owner = (fl_owner_t)lock_sop;
>> +
>> +	file_lock->fl_owner = (fl_owner_t)get_lockowner(lock_sop);
>>  	file_lock->fl_pid = current->tgid;
>>  	file_lock->fl_file = filp;
>>  	file_lock->fl_flags = FL_POSIX | FL_NFSD;
>> +	file_lock->fl_ops = &nfsd4_fl_lock_ops;
>>  	file_lock->fl_start = lock->lk_offset;
>>  	file_lock->fl_end = last_byte_offset(lock->lk_offset, lock->lk_length);
>>  	nfs4_transform_lock_offset(file_lock);
>> @@ -5399,6 +5424,7 @@ nfsd4_locku(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>>  	struct nfs4_ol_stateid *stp;
>>  	struct file *filp = NULL;
>>  	struct file_lock *file_lock = NULL;
>> +	struct nfs4_lockowner *lock_sop = NULL;
>>  	__be32 status;
>>  	int err;
>>  	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
>> @@ -5420,6 +5446,8 @@ nfsd4_locku(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>>  		status = nfserr_lock_range;
>>  		goto put_stateid;
>>  	}
>> +
>> +	lock_sop = lockowner(stp->st_stateowner);
>>  	file_lock = locks_alloc_lock();
>>  	if (!file_lock) {
>>  		dprintk("NFSD: %s: unable to allocate lock!\n", __func__);
>> @@ -5428,10 +5456,11 @@ nfsd4_locku(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>>  	}
>>  	locks_init_lock(file_lock);
>>  	file_lock->fl_type = F_UNLCK;
>> -	file_lock->fl_owner = (fl_owner_t)lockowner(stp->st_stateowner);
>> +	file_lock->fl_owner = (fl_owner_t)get_lockowner(lock_sop);
>>  	file_lock->fl_pid = current->tgid;
>>  	file_lock->fl_file = filp;
>>  	file_lock->fl_flags = FL_POSIX | FL_NFSD;
>> +	file_lock->fl_ops = &nfsd4_fl_lock_ops;
>>  	file_lock->fl_start = locku->lu_offset;
>>  
>>  	file_lock->fl_end = last_byte_offset(locku->lu_offset,
> 
> (Sorry I didn't respond to these before -- I no longer work for Red
>  Hat, so emails to jlayton@redhat.com don't get to me).
> 
> This looks really wrong. In this case, knfsd is acting as a
> (server-side) lock manager, not a filesystem:
> 
>         const struct file_lock_operations *fl_ops;      /* Callbacks for filesystems */
>         const struct lock_manager_operations *fl_lmops; /* Callbacks for lockmanagers */
> 
> So really, taking and putting of lockowner references is really the
> purview of the lockmanager. If you had a filesystem that set fl_ops and
> was exportable, then this will likely break it.
> 
> The fact that the file locking code uses struct file_lock for lock
> requests and for tracking the locks themselves makes for a horribly
> confusing interface. If I were designing this from scratch I would have
> made those two distinct structures. Maybe we should do that anyway
> sometime.
> 
> What you probably ought want to do is to declare some new fl_lmops for
> taking and putting lockowner references and add hooks to call them at
> the appropriate places.

Sorry for my fault, a new resolve as v2 has be send.
Please help have a check, thank you very much.

thanks,
Kinglong Mee