nfsd41: implement NFS4_SHARE_WANT_NO_DELEG, NFS4_OPEN_DELEGATE_NONE_EXT, why_no_deleg

Respect client request for not getting a delegation in NFSv4.1
Appropriately return delegation "type" NFS4_OPEN_DELEGATE_NONE_EXT
and WND4_NOT_WANTED reason.

[nfsd41: add missing break when encoding op_why_no_deleg]
Signed-off-by: Benny Halevy <bhalevy@tonian.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 53 insertions, 7 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index f1b74a74ec49..967c677c2e54 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2866,7 +2866,7 @@ nfs4_open_delegation(struct svc_fh *fh, struct nfsd4_open *open, struct nfs4_ol_
         struct nfs4_delegation *dp;
         struct nfs4_openowner *oo = container_of(stp->st_stateowner, struct nfs4_openowner, oo_owner);
         int cb_up;
-        int status, flag = 0;
+        int status = 0, flag = 0;
 
         cb_up = nfsd4_cb_channel_good(oo->oo_owner.so_client);
         flag = NFS4_OPEN_DELEGATE_NONE;
@@ -2907,11 +2907,32 @@ nfs4_open_delegation(struct svc_fh *fh, struct nfsd4_open *open, struct nfs4_ol_
         dprintk("NFSD: delegation stateid=" STATEID_FMT "\n",
                 STATEID_VAL(&dp->dl_stid.sc_stateid));
 out:
-        if (open->op_claim_type == NFS4_OPEN_CLAIM_PREVIOUS
-                        && flag == NFS4_OPEN_DELEGATE_NONE
-                        && open->op_delegate_type != NFS4_OPEN_DELEGATE_NONE)
-                dprintk("NFSD: WARNING: refusing delegation reclaim\n");
         open->op_delegate_type = flag;
+        if (flag == NFS4_OPEN_DELEGATE_NONE) {
+                if (open->op_claim_type == NFS4_OPEN_CLAIM_PREVIOUS &&
+                    open->op_delegate_type != NFS4_OPEN_DELEGATE_NONE)
+                        dprintk("NFSD: WARNING: refusing delegation reclaim\n");
+
+                if (open->op_deleg_want) {
+                        open->op_delegate_type = NFS4_OPEN_DELEGATE_NONE_EXT;
+                        if (status == -EAGAIN)
+                                open->op_why_no_deleg = WND4_CONTENTION;
+                        else {
+                                open->op_why_no_deleg = WND4_RESOURCE;
+                                switch (open->op_deleg_want) {
+                                case NFS4_SHARE_WANT_READ_DELEG:
+                                case NFS4_SHARE_WANT_WRITE_DELEG:
+                                case NFS4_SHARE_WANT_ANY_DELEG:
+                                        break;
+                                case NFS4_SHARE_WANT_CANCEL:
+                                        open->op_why_no_deleg = WND4_CANCELLED;
+                                        break;
+                                case NFS4_SHARE_WANT_NO_DELEG:
+                                        BUG();  /* not supposed to get here */
+                                }
+                        }
+                }
+        }
         return;
 out_free:
         nfs4_put_delegation(dp);
@@ -2981,20 +3002,45 @@ nfsd4_process_open2(struct svc_rqst *rqstp, struct svc_fh *current_fh, struct nf
         update_stateid(&stp->st_stid.sc_stateid);
         memcpy(&open->op_stateid, &stp->st_stid.sc_stateid, sizeof(stateid_t));
 
-        if (nfsd4_has_session(&resp->cstate))
+        if (nfsd4_has_session(&resp->cstate)) {
                 open->op_openowner->oo_flags |= NFS4_OO_CONFIRMED;
 
+                if (open->op_deleg_want & NFS4_SHARE_WANT_NO_DELEG) {
+                        open->op_delegate_type = NFS4_OPEN_DELEGATE_NONE_EXT;
+                        open->op_why_no_deleg = WND4_NOT_WANTED;
+                        goto nodeleg;
+                }
+        }
+
         /*
         * Attempt to hand out a delegation. No error return, because the
         * OPEN succeeds even if we fail.
         */
         nfs4_open_delegation(current_fh, open, stp);
-
+nodeleg:
         status = nfs_ok;
 
         dprintk("%s: stateid=" STATEID_FMT "\n", __func__,
                 STATEID_VAL(&stp->st_stid.sc_stateid));
 out:
+        /* 4.1 client trying to upgrade/downgrade delegation? */
+        if (open->op_delegate_type == NFS4_OPEN_DELEGATE_NONE && dp &&
+            open->op_deleg_want) {
+                if (open->op_deleg_want == NFS4_SHARE_WANT_READ_DELEG &&
+                    dp->dl_type == NFS4_OPEN_DELEGATE_WRITE) {
+                        open->op_delegate_type = NFS4_OPEN_DELEGATE_NONE_EXT;
+                        open->op_why_no_deleg = WND4_NOT_SUPP_DOWNGRADE;
+                } else if (open->op_deleg_want == NFS4_SHARE_WANT_WRITE_DELEG &&
+                           dp->dl_type == NFS4_OPEN_DELEGATE_WRITE) {
+                        open->op_delegate_type = NFS4_OPEN_DELEGATE_NONE_EXT;
+                        open->op_why_no_deleg = WND4_NOT_SUPP_UPGRADE;
+                }
+                /* Otherwise the client must be confused wanting a delegation
+                 * it already has, therefore we don't return
+                 * NFS4_OPEN_DELEGATE_NONE_EXT and reason.
+                 */
+        }
+
         if (fp)
                 put_nfs4_file(fp);
         if (status == 0 && open->op_claim_type == NFS4_OPEN_CLAIM_PREVIOUS)