Re: [PATCH 2/4] NFSD: Rervert "knfsd: locks: flag NFSv4-owned locks"

[Kinglong Mee <kinglongmee@gmail.com>]

On 7/8/2014 01:26, Jeff Layton wrote:
> On Mon, 07 Jul 2014 22:12:21 +0800
> Kinglong Mee <kinglongmee@gmail.com> wrote:
> 
>> Commit d5b9026a67 ([PATCH] knfsd: locks: flag NFSv4-owned locks) using
>> fl_lmops field in file_lock for checking nfsd4 lockowner.
>>
>> But, commit 1a747ee0cc (locks: don't call ->copy_lock methods on return of conflicting locks) causes the fl_lmops of conflock for nfsd4_lock always be NULL.
>>
>> Also, commit 0996905f93 (lockd: posix_test_lock() should not call locks_copy_lock()) caused the fl_lmops of conflock for nfsd4_lockt always be NULL too.
>>
>> So that, using fl_lmops cannot checking nfsd4 lockowner for it always be NULL.
>>
>> This patch save the strhashval in nfs4_lockowner for searching lockownerlike before.
>>
>> Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
>> ---
>>  fs/nfsd/nfs4state.c | 35 +++++++++++++++++++++++------------
>>  fs/nfsd/state.h     |  1 +
>>  2 files changed, 24 insertions(+), 12 deletions(-)
>>
>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>> index 9b9474c..1b5afc1 100644
>> --- a/fs/nfsd/nfs4state.c
>> +++ b/fs/nfsd/nfs4state.c
>> @@ -4282,18 +4282,30 @@ nfs4_transform_lock_offset(struct file_lock *lock)
>>  		lock->fl_end = OFFSET_MAX;
>>  }
>>  
>> -/* Hack!: For now, we're defining this just so we can use a pointer to it
>> - * as a unique cookie to identify our (NFSv4's) posix locks. */
>> -static const struct lock_manager_operations nfsd_posix_mng_ops  = {
>> -};
>> +static bool
>> +nfs4_verify_lock_stateowner(struct nfs4_lockowner *lo, struct nfsd_net *nn)
>> +{
>> +	struct nfs4_stateowner *local = NULL;
>> +	unsigned hashval = lo->lo_hashval;
>> +
>> +	if (hashval >= OWNER_HASH_SIZE)
>> +		return false;
>> +
>> +	list_for_each_entry(local, &nn->ownerstr_hashtbl[hashval], so_strhash) {
>> +		if (local == &lo->lo_owner)
>> +			return true;
>> +	}
>> +
>> +	return false;
>> +}
>>  
>>  static inline void
>> -nfs4_set_lock_denied(struct file_lock *fl, struct nfsd4_lock_denied *deny)
>> +nfs4_set_lock_denied(struct file_lock *fl, struct nfsd4_lock_denied *deny,
>> +			struct nfsd_net *nn)
>>  {
>> -	struct nfs4_lockowner *lo;
>> +	struct nfs4_lockowner *lo = (struct nfs4_lockowner *) fl->fl_owner;
>>  
>> -	if (fl->fl_lmops == &nfsd_posix_mng_ops) {
>> -		lo = (struct nfs4_lockowner *) fl->fl_owner;
>> +	if (nfs4_verify_lock_stateowner(lo, nn)) {
>>  		deny->ld_owner.data = kmemdup(lo->lo_owner.so_owner.data,
>>  					lo->lo_owner.so_owner.len, GFP_KERNEL);
>>  		if (!deny->ld_owner.data)
>> @@ -4350,6 +4362,7 @@ alloc_init_lock_stateowner(unsigned int strhashval, struct nfs4_client *clp, str
>>  	if (!lo)
>>  		return NULL;
>>  	INIT_LIST_HEAD(&lo->lo_owner.so_stateids);
>> +	lo->lo_hashval = strhashval;
>>  	lo->lo_owner.so_is_open_owner = 0;
>>  	/* It is the openowner seqid that will be incremented in encode in the
>>  	 * case of new lockowners; so increment the lock seqid manually: */
>> @@ -4564,7 +4577,6 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>>  	file_lock->fl_pid = current->tgid;
>>  	file_lock->fl_file = filp;
>>  	file_lock->fl_flags = FL_POSIX;
>> -	file_lock->fl_lmops = &nfsd_posix_mng_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);
>> @@ -4587,7 +4599,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>>  	case (EAGAIN):		/* conflock holds conflicting lock */
>>  		status = nfserr_denied;
>>  		dprintk("NFSD: nfsd4_lock: conflicting lock found!\n");
>> -		nfs4_set_lock_denied(conflock, &lock->lk_denied);
>> +		nfs4_set_lock_denied(conflock, &lock->lk_denied, nn);
>>  		break;
>>  	case (EDEADLK):
>>  		status = nfserr_deadlock;
>> @@ -4695,7 +4707,7 @@ nfsd4_lockt(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>>  
>>  	if (file_lock->fl_type != F_UNLCK) {
>>  		status = nfserr_denied;
>> -		nfs4_set_lock_denied(file_lock, &lockt->lt_denied);
>> +		nfs4_set_lock_denied(file_lock, &lockt->lt_denied, nn);
>>  	}
>>  out:
>>  	nfs4_unlock_state();
>> @@ -4746,7 +4758,6 @@ nfsd4_locku(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
>>  	file_lock->fl_pid = current->tgid;
>>  	file_lock->fl_file = filp;
>>  	file_lock->fl_flags = FL_POSIX;
>> -	file_lock->fl_lmops = &nfsd_posix_mng_ops;
>>  	file_lock->fl_start = locku->lu_offset;
>>  
>>  	file_lock->fl_end = last_byte_offset(locku->lu_offset,
>> diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
>> index 1848fed..9ecae58 100644
>> --- a/fs/nfsd/state.h
>> +++ b/fs/nfsd/state.h
>> @@ -362,6 +362,7 @@ struct nfs4_openowner {
>>  
>>  struct nfs4_lockowner {
>>  	struct nfs4_stateowner	lo_owner; /* must be first element */
>> +	unsigned int		lo_hashval;
> 
> Actually, I have another comment here too. I'm not sure there's a lot
> of value in tracking the lo_hashval here. Why not just recompute it in
> nfs4_verify_lock_stateowner?

No, ownerstr_hashval() needs a client which holds the conflicting lock,
in nfsd4_lock/nfsd4_lockt cannot know the client from vfs_lock_file()
 or vfs_test_lock().

> 
> You'd need to pass down a pointer to the nfs4_client in order to do so,
> but you could do that instead of passing down 'nn' and then just call
> net_generic on clp->net where you needed it.

I find patch "[PATCH v3 069/114] nfsd: Move the open owner hash table into struct nfs4_client"
have remove the client argument from ownerstr_hashval().

So, the lo_hashval isn't needed after that patch.
After Bruce merging that patch, I will resend a new patch recomputing
the hash value instead recording in lo_hashval.

thanks,
Kinglong Mee