[PATCH v3 4/5] NFSD: Increase minimum size of slot replay cache

[Chuck Lever <cel@kernel.org>]

From: Chuck Lever <chuck.lever@oracle.com>

NFSD caches solo SEQUENCE even when sa_cachethis is false. Ensure
there is enough space in each slot replay cache, even when the
client requested a zero ca_maxresponsesize_cached.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfsd/nfs4state.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 7b80f00fb32c..7d297ac2bf2b 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2024,11 +2024,12 @@ static struct nfsd4_slot *nfsd4_alloc_slot(struct nfsd4_channel_attrs *fattrs,
 	size_t size;
 
 	/*
-	 * The RPC and NFS session headers are never saved in
-	 * the slot reply cache buffer.
+	 * Reserve enough space to handle solo SEQUENCE operations,
+	 * which are always cached.
 	 */
 	size = fattrs->maxresp_cached < NFSD_MIN_HDR_SEQ_SZ ?
-		0 : fattrs->maxresp_cached - NFSD_MIN_HDR_SEQ_SZ;
+		NFSD_MIN_HDR_SEQ_SZ :
+		fattrs->maxresp_cached - NFSD_MIN_HDR_SEQ_SZ;
 
 	slot = kzalloc(struct_size(slot, sl_data, size), gfp);
 	if (!slot)
-- 
2.51.0