Since the beginning, svcsock has built a received RPC Call message
by populating the xdr_buf's head, then placing the remaining
message bytes in the xdr_buf's page list. The xdr_buf's tail is
never populated.
This means that an NFSv4 COMPOUND containing an NFS WRITE operation
plus trailing operations has a page list that contains the WRITE
data payload followed by the trailing operations. NFSv4 XDR decoders
will not look in the xdr_buf's tail, ever, because svcsock never put
anything there.
To support transports that can pass the write payload in the
xdr_buf's pagelist and trailing content in the xdr_buf's tail,
introduce logic in READ_BUF that switches to the xdr_buf's tail vec
when the decoder runs out of content in rq_arg.pages.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
fs/nfsd/nfs4xdr.c | 20 ++++++++++++++++++++
fs/nfsd/xdr4.h | 1 +
2 files changed, 21 insertions(+)
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 7c48d68..a9f88cf 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -159,6 +159,25 @@ static __be32 *read_buf(struct nfsd4_compoundargs *argp, u32 nbytes)
*/
unsigned int avail = (char *)argp->end - (char *)argp->p;
__be32 *p;
+
+ if (argp->pagelen == 0) {
+ struct kvec *vec = &argp->rqstp->rq_arg.tail[0];
+
+ if (!argp->tail) {
+ argp->tail = true;
+ avail = vec->iov_len;
+ argp->p = vec->iov_base;
+ argp->end = vec->iov_base + avail;
+ }
+
+ if (avail < nbytes)
+ return NULL;
+
+ p = argp->p;
+ argp->p += XDR_QUADLEN(nbytes);
+ return p;
+ }
+
if (avail + argp->pagelen < nbytes)
return NULL;
if (avail + PAGE_SIZE < nbytes) /* need more than a page !! */
@@ -4573,6 +4592,7 @@ void nfsd4_release_compoundargs(struct svc_rqst *rqstp)
args->end = rqstp->rq_arg.head[0].iov_base + rqstp->rq_arg.head[0].iov_len;
args->pagelist = rqstp->rq_arg.pages;
args->pagelen = rqstp->rq_arg.page_len;
+ args->tail = false;
args->tmpp = NULL;
args->to_free = NULL;
args->ops = args->iops;
diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h
index 72c6ad1..bac91b1 100644
--- a/fs/nfsd/xdr4.h
+++ b/fs/nfsd/xdr4.h
@@ -614,6 +614,7 @@ struct nfsd4_compoundargs {
__be32 * end;
struct page ** pagelist;
int pagelen;
+ bool tail;
__be32 tmp[8];
__be32 * tmpp;
struct svcxdr_tmpbuf *to_free;
--
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