[pnfs] [PATCH 1/1] Replaced BUG() with BUG_ON()

[Benny Halevy]

The problem I hit is caused by the fact that that I'm not using the file layout.

nfs_write_rpcsetup() does not set data->session before calling
pnfs_try_to_write_data().

When we do the pnfs write via the layout driver there's indeed no
session in my case.

The files layout driver sets data->session to the DS session as
		data->session = dserver.dev_item->clp->cl_session;

and on the async callback path pnfs4_write_done() is called.
[note, without properly going through pnfs4_proc_write_setup in my case,
it is called only when writing to the MDS to to the DS via calls
to nfs_initiate_write()]

pnfs4_write_done(), in turn, calls the NFS_SERVER(inode)->rpc_ops->
sequence_done if not null, unconditionally in all cases.

The fix I tested is attached.  It calls sequence_done only if data->session
is not NULL.

Another question is whether calling server->rpc_ops->sequence_done
is appropriate both for the MDS and for the DS case.

Benny
 
Benny Halevy wrote:
> iyer at netapp.com wrote:
>> From: Rahul Iyer <iyer at netapp.com>
>>
>> Replaced instances of
>>
>> if (....)
>> 	BUG();
>>
>> with
>>
>> BUG_on(...);
>>
>> Signed-off-by: Rahul Iyer <iyer at netapp.com>
>> ---
>>  fs/nfs/nfs4proc.c |   31 +++++++++++++------------------
>>  1 files changed, 13 insertions(+), 18 deletions(-)
>>
>> diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
>> index b4ce093..89702cf 100644
>> --- a/fs/nfs/nfs4proc.c
>> +++ b/fs/nfs/nfs4proc.c
>> @@ -222,10 +222,9 @@ static int nfs41_proc_sequence_done(struct nfs4_session *session, struct nfs41_s
>>  	unsigned long timestamp;
>>  	struct nfs4_client *clp;
>>  
>> -	if (!session || !(clp = session->client)) {
>> -		printk(KERN_EMERG "%s is NULL!!!\n", (!session)?"session":"clp");
>> -		BUG();
>> -	}
>> +	BUG_ON(!session);
> 
> Rahul, this BUG_ON introduces a bug :-(
> Previously the function just returned if !session,
> now it BUG()'s.
> 
>> +	clp = session->client;
>> +	BUG_ON(!clp);
>>  
> 
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