controller: Fix issue with ct_commit encode.

Action length is getting set incorrectly during ct_commit encode
due to which ct action is getting skipped  during phsycial flows
creation. This issue is noticed only if ct_commit is prefixed
with other actions.

logical flow: reg8[17] = 1; ct_commit { ct_mark.blocked = 1; };
without fix: encodes as set_field:0x2000000000000/0x2000000000000->xreg4
with fix: encodes as set_field:0x2000000000000/0x2000000000000->xreg4,ct(commit,zone=NXM_NX_REG13[0..15],exec(set_field:0x1/0x1->ct_mark))

Signed-off-by: Naveen Yerramneni <naveen.yerramneni@nutanix.com>
Signed-off-by: Dumitru Ceara <dceara@redhat.com>
(cherry picked from commit 7b43959)

lib/actions.c

@@ -875,6 +875,9 @@ encode_CT_COMMIT_V2(const struct ovnact_nest *on,
                     const struct ovnact_encode_params *ep OVS_UNUSED,
                     struct ofpbuf *ofpacts)
 {
+    size_t ct_offset = ofpacts->size;
+    ofpbuf_pull(ofpacts, ct_offset);
+
     struct ofpact_conntrack *ct = ofpact_put_CT(ofpacts);
     ct->flags = NX_CT_F_COMMIT;
     ct->recirc_table = NX_CT_RECIRC_NONE;
@@ -906,6 +909,7 @@ encode_CT_COMMIT_V2(const struct ovnact_nest *on,
     ofpacts->header = ofpbuf_push_uninit(ofpacts, set_field_offset);
     ct = ofpacts->header;
     ofpact_finish(ofpacts, &ct->ofpact);
+    ofpbuf_push_uninit(ofpacts, ct_offset);
 }
 
 static void

tests/ovn.at

@@ -1304,6 +1304,9 @@ ct_commit { ct_label=0x181716151413121110090807060504030201; };
     141-bit constant is not compatible with 128-bit field ct_label.
 ct_commit { ip4.dst = 192.168.0.1; };
     Field ip4.dst is not modifiable.
+reg8[17] = 1; ct_commit { ct_mark.blocked = 1; };
+    encodes as set_field:0x2000000000000/0x2000000000000->xreg4,ct(commit,zone=NXM_NX_REG13[0..15],exec(set_field:0x1/0x1->ct_mark))
+    has prereqs ip
 
 # Legact ct_commit_v1 action.
 ct_commit();