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nfsd: stop pretending that we cache the SEQUENCE reply. 

nfsd does not cache the reply to a SEQUENCE.  As the comment above
nfsd4_replay_cache_entry() says:

 * The sequence operation is not cached because we can use the slot and
 * session values.

The comment above nfsd4_cache_this() suggests otherwise.

 * The session reply cache only needs to cache replies that the client
 * actually asked us to.  But it's almost free for us to cache compounds
 * consisting of only a SEQUENCE op, so we may as well cache those too.
 * Also, the protocol doesn't give us a convenient response in the case
 * of a replay of a solo SEQUENCE op that wasn't cached

The code in nfsd4_store_cache_entry() makes it clear that only responses
beyond 'cstate.data_offset' are actually cached, and data_offset is set
at the end of nfsd4_encode_sequence() *after* the sequence response has
been encoded.

This patch simplifies code and removes the confusing comments.

- nfsd4_is_solo_sequence() is discarded as not-useful.
- nfsd4_cache_this() is now trivial so it too is discarded with the
  code placed in-line at the one call-site in nfsd4_store_cache_entry().
- nfsd4_enc_sequence_replay() is open-coded in to
  nfsd4_replay_cache_entry(), and then simplified to (hopefully) make
  the process of replaying a reply clearer.

Signed-off-by: NeilBrown <neil@brown.name>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
pull/1354/merge
NeilBrown 2025-10-16 09:49:58 -04:00 committed by Chuck Lever
parent 8320b75b2b
commit fceb8734e7
2 changed files with 18 additions and 61 deletions
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58
fs/nfsd/nfs4state.c
View File

@ -3508,7 +3508,7 @@ nfsd4_store_cache_entry(struct nfsd4_compoundres *resp)
free_svc_cred(&slot->sl_cred);
copy_cred(&slot->sl_cred, &resp->rqstp->rq_cred);
if (!nfsd4_cache_this(resp)) {
if (!(resp->cstate.slot->sl_flags & NFSD4_SLOT_CACHETHIS)) {
slot->sl_flags &= ~NFSD4_SLOT_CACHED;
return;
}
@ -3522,41 +3522,6 @@ nfsd4_store_cache_entry(struct nfsd4_compoundres *resp)
return;
}
/*
* Encode the replay sequence operation from the slot values.
* If cachethis is FALSE encode the uncached rep error on the next
* operation which sets resp->p and increments resp->opcnt for
* nfs4svc_encode_compoundres.
*
*/
static __be32
nfsd4_enc_sequence_replay(struct nfsd4_compoundargs *args,
struct nfsd4_compoundres *resp)
{
struct nfsd4_op *op;
struct nfsd4_slot *slot = resp->cstate.slot;
/* Encode the replayed sequence operation */
op = &args->ops[resp->opcnt - 1];
nfsd4_encode_operation(resp, op);
if (slot->sl_flags & NFSD4_SLOT_CACHED)
return op->status;
if (args->opcnt == 1) {
/*
* The original operation wasn't a solo sequence--we
* always cache those--so this retry must not match the
* original:
*/
op->status = nfserr_seq_false_retry;
} else {
op = &args->ops[resp->opcnt++];
op->status = nfserr_retry_uncached_rep;
nfsd4_encode_operation(resp, op);
}
return op->status;
}
/*
* The sequence operation is not cached because we can use the slot and
* session values.
@ -3565,17 +3530,30 @@ static __be32
nfsd4_replay_cache_entry(struct nfsd4_compoundres *resp,
struct nfsd4_sequence *seq)
{
struct nfsd4_compoundargs *args = resp->rqstp->rq_argp;
struct nfsd4_slot *slot = resp->cstate.slot;
struct xdr_stream *xdr = resp->xdr;
__be32 *p;
__be32 status;
dprintk("--> %s slot %p\n", __func__, slot);
status = nfsd4_enc_sequence_replay(resp->rqstp->rq_argp, resp);
if (status)
return status;
/* Always encode the SEQUENCE response. */
nfsd4_encode_operation(resp, &args->ops[0]);
if (args->opcnt == 1)
/* A solo SEQUENCE - nothing was cached */
return args->ops[0].status;
if (!(slot->sl_flags & NFSD4_SLOT_CACHED)) {
/* We weren't asked to cache this. */
struct nfsd4_op *op;
op = &args->ops[resp->opcnt++];
op->status = nfserr_retry_uncached_rep;
nfsd4_encode_operation(resp, op);
return op->status;
}
/* return reply from cache */
p = xdr_reserve_space(xdr, slot->sl_datalen);
if (!p) {
WARN_ON_ONCE(1);

21
fs/nfsd/xdr4.h
View File

@ -924,27 +924,6 @@ struct nfsd4_compoundres {
struct nfsd4_compound_state cstate;
};
static inline bool nfsd4_is_solo_sequence(struct nfsd4_compoundres *resp)
{
struct nfsd4_compoundargs *args = resp->rqstp->rq_argp;
return resp->opcnt == 1 && args->ops[0].opnum == OP_SEQUENCE;
}
/*
* The session reply cache only needs to cache replies that the client
* actually asked us to. But it's almost free for us to cache compounds
* consisting of only a SEQUENCE op, so we may as well cache those too.
* Also, the protocol doesn't give us a convenient response in the case
* of a replay of a solo SEQUENCE op that wasn't cached
* (RETRY_UNCACHED_REP can only be returned in the second op of a
* compound).
*/
static inline bool nfsd4_cache_this(struct nfsd4_compoundres *resp)
{
return (resp->cstate.slot->sl_flags & NFSD4_SLOT_CACHETHIS)
|| nfsd4_is_solo_sequence(resp);
}
static inline bool nfsd4_last_compound_op(struct svc_rqst *rqstp)
{
struct nfsd4_compoundres *resp = rqstp->rq_resp;