nfsd4: better reservation of head space for krb5

RPC_MAX_AUTH_SIZE is scattered around several places.  Better to set it
once in the auth code, where this kind of estimate should be made.  And
while we're at it we can leave it zero when we're not using krb5i or
krb5p.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

3 files changed, 6 insertions, 5 deletions

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 2d786b813c7e..16e71d033ea5 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1261,13 +1261,13 @@ static void svcxdr_init_encode(struct svc_rqst *rqstp,
         xdr->buf = buf;
         xdr->iov = head;
         xdr->p   = head->iov_base + head->iov_len;
-        xdr->end = head->iov_base + PAGE_SIZE - 2 * RPC_MAX_AUTH_SIZE;
+        xdr->end = head->iov_base + PAGE_SIZE - rqstp->rq_auth_slack;
         /* Tail and page_len should be zero at this point: */
         buf->len = buf->head[0].iov_len;
         xdr->scratch.iov_len = 0;
         xdr->page_ptr = buf->pages;
         buf->buflen = PAGE_SIZE * (1 + rqstp->rq_page_end - buf->pages)
-                - 2 * RPC_MAX_AUTH_SIZE;
+                - rqstp->rq_auth_slack;
 }
 
 /*
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 62b882dc48ec..d0a016a502be 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2288,7 +2288,7 @@ nfsd4_sequence(struct svc_rqst *rqstp,
                         session->se_fchannel.maxresp_sz;
         status = (seq->cachethis) ? nfserr_rep_too_big_to_cache :
                                     nfserr_rep_too_big;
-        if (xdr_restrict_buflen(xdr, buflen - 2 * RPC_MAX_AUTH_SIZE))
+        if (xdr_restrict_buflen(xdr, buflen - rqstp->rq_auth_slack))
                 goto out_put_session;
         svc_reserve(rqstp, buflen);
 
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 3e347a1caec4..470fe8998c9b 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -1611,7 +1611,8 @@ nfsd4_decode_compound(struct nfsd4_compoundargs *argp)
         DECODE_HEAD;
         struct nfsd4_op *op;
         bool cachethis = false;
-        int max_reply = 2 * RPC_MAX_AUTH_SIZE + 8; /* opcnt, status */
+        int auth_slack= argp->rqstp->rq_auth_slack;
+        int max_reply = auth_slack + 8; /* opcnt, status */
         int readcount = 0;
         int readbytes = 0;
         int i;
@@ -1677,7 +1678,7 @@ nfsd4_decode_compound(struct nfsd4_compoundargs *argp)
         svc_reserve(argp->rqstp, max_reply + readbytes);
         argp->rqstp->rq_cachetype = cachethis ? RC_REPLBUFF : RC_NOCACHE;
 
-        if (readcount > 1 || max_reply > PAGE_SIZE - 2*RPC_MAX_AUTH_SIZE)
+        if (readcount > 1 || max_reply > PAGE_SIZE - auth_slack)
                 argp->rqstp->rq_splice_ok = false;
 
         DECODE_TAIL;