git: 84800ef64b9f - stable/11 - nfsd: fix replies from session cache for retried RPCs

[Rick Macklem]

The branch stable/11 has been updated by rmacklem:

URL: https://cgit.FreeBSD.org/src/commit/?id=84800ef64b9f8b75466c9622b9c105b227a5e2d3

commit 84800ef64b9f8b75466c9622b9c105b227a5e2d3
Author:     Rick Macklem <rmacklem at FreeBSD.org>
AuthorDate: 2021-04-08 21:04:22 +0000
Commit:     Rick Macklem <rmacklem at FreeBSD.org>
CommitDate: 2021-04-27 23:08:47 +0000

    nfsd: fix replies from session cache for retried RPCs
    
    Recent testing of network partitioning a FreeBSD NFSv4.1
    server from a Linux NFSv4.1 client identified problems
    with both the FreeBSD server and Linux client.
    
    The FreeBSD server failed to reply using the cached
    reply in the session slot when an RPC was retried on
    the session slot, as indicated by same slot sequence#.
    
    This patch fixes this.  It should also fix a similar
    failure for NFSv4.0 mounts, when the sequence# in
    the open/lock_owner requires a reply be done from
    an entry locked into the DRC.
    
    This fix affects the fairly rare case where a NFSv4
    client retries a non-idempotent RPC, such as a lock
    operation.  Note that retries only occur after the
    client has needed to create a new TCP connection.
    
    (cherry picked from commit 05a39c2c1c18cd0c4382a4f58e0952d3f77e7dfa)
---
 sys/fs/nfsserver/nfs_nfsdkrpc.c | 7 ++++++-
 sys/fs/nfsserver/nfs_nfsdsubs.c | 2 ++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/sys/fs/nfsserver/nfs_nfsdkrpc.c b/sys/fs/nfsserver/nfs_nfsdkrpc.c
index e1d82b33eb81..f77af2779847 100644
--- a/sys/fs/nfsserver/nfs_nfsdkrpc.c
+++ b/sys/fs/nfsserver/nfs_nfsdkrpc.c
@@ -388,8 +388,13 @@ nfs_proc(struct nfsrv_descript *nd, u_int32_t xid, SVCXPRT *xprt,
 				m = NULL;
 			if ((nd->nd_flag & ND_HASSEQUENCE) != 0)
 				nfsrv_cache_session(nd, &m);
-			if (nd->nd_repstat == NFSERR_REPLYFROMCACHE)
+			if (nd->nd_repstat == NFSERR_REPLYFROMCACHE) {
 				nd->nd_repstat = 0;
+				if (m != NULL) {
+					m_freem(nd->nd_mreq);
+					nd->nd_mreq = m;
+				}
+			}
 			cacherep = RC_REPLY;
 		} else {
 			if (nd->nd_repstat == NFSERR_DONTREPLY)
diff --git a/sys/fs/nfsserver/nfs_nfsdsubs.c b/sys/fs/nfsserver/nfs_nfsdsubs.c
index 382ed291c38b..0080f26ea643 100644
--- a/sys/fs/nfsserver/nfs_nfsdsubs.c
+++ b/sys/fs/nfsserver/nfs_nfsdsubs.c
@@ -1506,6 +1506,8 @@ nfsd_errmap(struct nfsrv_descript *nd)
 		else if (nd->nd_repstat == NFSERR_MINORVERMISMATCH ||
 			 nd->nd_repstat == NFSERR_OPILLEGAL)
 			return (txdr_unsigned(nd->nd_repstat));
+		else if (nd->nd_repstat == NFSERR_REPLYFROMCACHE)
+			return (txdr_unsigned(NFSERR_IO));
 		else if ((nd->nd_flag & ND_NFSV41) != 0) {
 			if (nd->nd_repstat == EOPNOTSUPP)
 				nd->nd_repstat = NFSERR_NOTSUPP;