Re: [PATCH v2 2/4] NFSD: enable support for write delegation

[dai.ngo@oracle.com]

Thank you Jeff for your review.

On 5/15/23 4:25 AM, Jeff Layton wrote:
> On Sun, 2023-05-14 at 17:20 -0700, Dai Ngo wrote:
>> This patch grants write delegation for OPEN with NFS4_SHARE_ACCESS_WRITE
>> if there is no conflict with other OPENs.
>>
>> Write delegation conflict with another OPEN, REMOVE, RENAME and SETATTR
>> are handled the same as read delegation using notify_change,
>> try_break_deleg.
>>
>> Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
>> ---
>>   fs/nfsd/nfs4state.c | 24 ++++++++++++++++--------
>>   1 file changed, 16 insertions(+), 8 deletions(-)
>>
>> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
>> index 6e61fa3acaf1..09a9e16407f9 100644
>> --- a/fs/nfsd/nfs4state.c
>> +++ b/fs/nfsd/nfs4state.c
>> @@ -1144,7 +1144,7 @@ static void block_delegations(struct knfsd_fh *fh)
>>   
>>   static struct nfs4_delegation *
>>   alloc_init_deleg(struct nfs4_client *clp, struct nfs4_file *fp,
>> -		 struct nfs4_clnt_odstate *odstate)
>> +		struct nfs4_clnt_odstate *odstate, u32 dl_type)
>>   {
>>   	struct nfs4_delegation *dp;
>>   	long n;
>> @@ -1170,7 +1170,7 @@ alloc_init_deleg(struct nfs4_client *clp, struct nfs4_file *fp,
>>   	INIT_LIST_HEAD(&dp->dl_recall_lru);
>>   	dp->dl_clnt_odstate = odstate;
>>   	get_clnt_odstate(odstate);
>> -	dp->dl_type = NFS4_OPEN_DELEGATE_READ;
>> +	dp->dl_type = dl_type;
>>   	dp->dl_retries = 1;
>>   	dp->dl_recalled = false;
>>   	nfsd4_init_cb(&dp->dl_recall, dp->dl_stid.sc_client,
>> @@ -5451,6 +5451,7 @@ nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
>>   	struct nfs4_delegation *dp;
>>   	struct nfsd_file *nf;
>>   	struct file_lock *fl;
>> +	u32 deleg;
> nit: I'd probably call this "dl_type" for consistency

fix in v3.

>
>>   
>>   	/*
>>   	 * The fi_had_conflict and nfs_get_existing_delegation checks
>> @@ -5460,7 +5461,13 @@ nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
>>   	if (fp->fi_had_conflict)
>>   		return ERR_PTR(-EAGAIN);
>>   
>> -	nf = find_readable_file(fp);
>> +	if (open->op_share_access & NFS4_SHARE_ACCESS_WRITE) {
>> +		nf = find_writeable_file(fp);
>> +		deleg = NFS4_OPEN_DELEGATE_WRITE;
>> +	} else {
>> +		nf = find_readable_file(fp);
>> +		deleg = NFS4_OPEN_DELEGATE_READ;
>> +	}
>>   	if (!nf) {
>>   		/*
>>   		 * We probably could attempt another open and get a read
>> @@ -5491,11 +5498,11 @@ nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
>>   		return ERR_PTR(status);
>>   
>>   	status = -ENOMEM;
>> -	dp = alloc_init_deleg(clp, fp, odstate);
>> +	dp = alloc_init_deleg(clp, fp, odstate, deleg);
>>   	if (!dp)
>>   		goto out_delegees;
>>   
>> -	fl = nfs4_alloc_init_lease(dp, NFS4_OPEN_DELEGATE_READ);
>> +	fl = nfs4_alloc_init_lease(dp, deleg);
>>   	if (!fl)
>>   		goto out_clnt_odstate;
>>   
>> @@ -5583,6 +5590,7 @@ nfs4_open_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
>>   	struct svc_fh *parent = NULL;
>>   	int cb_up;
>>   	int status = 0;
>> +	u32 wdeleg = false;
> Shouldn't that be a bool? I don't think you actually need this variable
> anyway, you can just open-code the ternary condition in the assignment.

fix in v3.

-Dai

>
>>   
>>   	cb_up = nfsd4_cb_channel_good(oo->oo_owner.so_client);
>>   	open->op_recall = 0;
>> @@ -5590,8 +5598,6 @@ nfs4_open_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
>>   		case NFS4_OPEN_CLAIM_PREVIOUS:
>>   			if (!cb_up)
>>   				open->op_recall = 1;
>> -			if (open->op_delegate_type != NFS4_OPEN_DELEGATE_READ)
>> -				goto out_no_deleg;
>>   			break;
>>   		case NFS4_OPEN_CLAIM_NULL:
>>   			parent = currentfh;
>> @@ -5617,7 +5623,9 @@ nfs4_open_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
>>   	memcpy(&open->op_delegate_stateid, &dp->dl_stid.sc_stateid, sizeof(dp->dl_stid.sc_stateid));
>>   
>>   	trace_nfsd_deleg_read(&dp->dl_stid.sc_stateid);
>> -	open->op_delegate_type = NFS4_OPEN_DELEGATE_READ;
>> +	wdeleg = open->op_share_access & NFS4_SHARE_ACCESS_WRITE;
>> +	open->op_delegate_type = wdeleg ?
>> +			NFS4_OPEN_DELEGATE_WRITE : NFS4_OPEN_DELEGATE_READ;
>>   	nfs4_put_stid(&dp->dl_stid);
>>   	return;
>>   out_no_deleg: