> On May 21, 2023, at 11:56 PM, Dai Ngo <dai.ngo@xxxxxxxxxx> wrote:
>
>
> On 5/21/23 7:56 PM, dai.ngo@xxxxxxxxxx wrote:
>>
>> On 5/21/23 4:08 PM, Jeff Layton wrote:
>>> On Sat, 2023-05-20 at 14:36 -0700, Dai Ngo wrote:
>>>> If the GETATTR request on a file that has write delegation in effect
>>>> and the request attributes include the change info and size attribute
>>>> then the write delegation is recalled and NFS4ERR_DELAY is returned
>>>> for the GETATTR.
>>>>
>>>> Signed-off-by: Dai Ngo <dai.ngo@xxxxxxxxxx>
>>>> ---
>>>> fs/nfsd/nfs4xdr.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
>>>> 1 file changed, 45 insertions(+)
>>>>
>>>> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
>>>> index 76db2fe29624..e069b970f136 100644
>>>> --- a/fs/nfsd/nfs4xdr.c
>>>> +++ b/fs/nfsd/nfs4xdr.c
>>>> @@ -2920,6 +2920,46 @@ nfsd4_encode_bitmap(struct xdr_stream *xdr, u32 bmval0, u32 bmval1, u32 bmval2)
>>>> return nfserr_resource;
>>>> }
>>>> +static struct file_lock *
>>>> +nfs4_wrdeleg_filelock(struct svc_rqst *rqstp, struct inode *inode)
>>>> +{
>>>> + struct file_lock_context *ctx;
>>>> + struct file_lock *fl;
>>>> +
>>>> + ctx = locks_inode_context(inode);
>>>> + if (!ctx)
>>>> + return NULL;
>>>> + spin_lock(&ctx->flc_lock);
>>>> + if (!list_empty(&ctx->flc_lease)) {
>>>> + fl = list_first_entry(&ctx->flc_lease,
>>>> + struct file_lock, fl_list);
>>>> + if (fl->fl_type == F_WRLCK) {
>>>> + spin_unlock(&ctx->flc_lock);
>>>> + return fl;
>>>> + }
>>>> + }
>>>> + spin_unlock(&ctx->flc_lock);
>>>> + return NULL;
>>>> +}
>>>> +
>>>> +static __be32
>>>> +nfs4_handle_wrdeleg_conflict(struct svc_rqst *rqstp, struct inode *inode)
>>>> +{
>>>> + __be32 status;
>>>> + struct file_lock *fl;
>>>> + struct nfs4_delegation *dp;
>>>> +
>>>> + fl = nfs4_wrdeleg_filelock(rqstp, inode);
>>>> + if (!fl)
>>>> + return 0;
>>>> + dp = fl->fl_owner;
>>>> + if (dp->dl_recall.cb_clp == *(rqstp->rq_lease_breaker))
>>>> + return 0;
>>>> + refcount_inc(&dp->dl_stid.sc_count);
>>> Another question: Why are you taking a reference here at all?
>>
>> This is same as in nfsd_break_one_deleg and revoke_delegation.
>> I think it is to prevent the delegation to be freed while delegation
>> is being recalled.
>>
>>> AFAICT,
>>> you don't even look at the delegation again after that point, so it's
>>> not clear to me who's responsible for putting that reference.
>>
>> In v2, the sc_count is decrement by nfs4_put_stid. I forgot to do that
>> in V4. I'll add it back in v5.
>
> Actually the refcount is decremented after the CB_RECALL is done
> by nfs4_put_stid in nfsd4_cb_recall_release. So we don't have to
> decrement it here. This is to prevent the delegation to be free
> while the recall is being sent.
For v5, please add this good information to the documenting comment
for this function.
> -Dai
>
>>
>> Thanks,
>> -Dai
>>
>>>
>>>> + status = nfserrno(nfsd_open_break_lease(inode, NFSD_MAY_READ));
>>>> + return status;
>>>> +}
>>>> +
>>>> /*
>>>> * Note: @fhp can be NULL; in this case, we might have to compose the filehandle
>>>> * ourselves.
>>>> @@ -2966,6 +3006,11 @@ nfsd4_encode_fattr(struct xdr_stream *xdr, struct svc_fh *fhp,
>>>> if (status)
>>>> goto out;
>>>> }
>>>> + if (bmval0 & (FATTR4_WORD0_CHANGE | FATTR4_WORD0_SIZE)) {
>>>> + status = nfs4_handle_wrdeleg_conflict(rqstp, d_inode(dentry));
>>>> + if (status)
>>>> + goto out;
>>>> + }
>>>> err = vfs_getattr(&path, &stat,
>>>> STATX_BASIC_STATS | STATX_BTIME | STATX_CHANGE_COOKIE,
--
Chuck Lever
