[RFC PATCH] NFSD: Add a Kconfig setting to enable delegated timestamps

[cel@kernel.org]

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

After three tries, we still see test failures with delegated
timestamps. Disable them by default, but leave the implementation
intact so that development can continue.

X-Cc: stable@vger.kernel.org # v6.14
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfsd/Kconfig     | 12 +++++++++++-
 fs/nfsd/nfs4state.c | 16 ++++++++++++++--
 2 files changed, 25 insertions(+), 3 deletions(-)

This compiles. Initial testing shows that tests that were previously
failing are now passing. I would like to include this in v6.15, but
I will give it a little more time in nfsd-testing.

diff --git a/fs/nfsd/Kconfig b/fs/nfsd/Kconfig
index c0bd1509ccd4..792d3fed1b45 100644
--- a/fs/nfsd/Kconfig
+++ b/fs/nfsd/Kconfig
@@ -172,6 +172,16 @@ config NFSD_LEGACY_CLIENT_TRACKING
 	  recoverydir, or spawn a process directly using a usermodehelper
 	  upcall.
 
-	  These legacy client tracking methods have proven to be probelmatic
+	  These legacy client tracking methods have proven to be problematic
 	  and will be removed in the future. Say Y here if you need support
 	  for them in the interim.
+
+config NFSD_V4_DELEG_TIMESTAMPS
+	bool "Support delegated timestamps"
+	depends on NFSD_V4
+	default n
+	help
+	  NFSD implements delegated timestamps according to
+	  draft-ietf-nfsv4-delstid-08 "Extending the Opening of Files". This
+	  is currently an experimental feature and is therefore left disabled
+	  by default.
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 2da700635955..2bd63594d8da 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -5948,11 +5948,23 @@ nfsd4_verify_setuid_write(struct nfsd4_open *open, struct nfsd_file *nf)
 	return 0;
 }
 
+#ifdef CONFIG_NFSD_V4_DELEG_TIMESTAMPS
+static bool nfsd4_want_deleg_timestamps(const struct nfsd4_open *open)
+{
+	return open->op_deleg_want & OPEN4_SHARE_ACCESS_WANT_DELEG_TIMESTAMPS;
+}
+#else /* CONFIG_NFSD_V4_DELEG_TIMESTAMPS */
+static bool nfsd4_want_deleg_timestamps(const struct nfsd4_open *open)
+{
+	return false;
+}
+#endif /* CONFIG NFSD_V4_DELEG_TIMESTAMPS */
+
 static struct nfs4_delegation *
 nfs4_set_delegation(struct nfsd4_open *open, struct nfs4_ol_stateid *stp,
 		    struct svc_fh *parent)
 {
-	bool deleg_ts = open->op_deleg_want & OPEN4_SHARE_ACCESS_WANT_DELEG_TIMESTAMPS;
+	bool deleg_ts = nfsd4_want_deleg_timestamps(open);
 	struct nfs4_client *clp = stp->st_stid.sc_client;
 	struct nfs4_file *fp = stp->st_stid.sc_file;
 	struct nfs4_clnt_odstate *odstate = stp->st_clnt_odstate;
@@ -6193,8 +6205,8 @@ nfs4_open_delegation(struct svc_rqst *rqstp, struct nfsd4_open *open,
 		     struct nfs4_ol_stateid *stp, struct svc_fh *currentfh,
 		     struct svc_fh *fh)
 {
-	bool deleg_ts = open->op_deleg_want & OPEN4_SHARE_ACCESS_WANT_DELEG_TIMESTAMPS;
 	struct nfs4_openowner *oo = openowner(stp->st_stateowner);
+	bool deleg_ts = nfsd4_want_deleg_timestamps(open);
 	struct nfs4_client *clp = stp->st_stid.sc_client;
 	struct svc_fh *parent = NULL;
 	struct nfs4_delegation *dp;
-- 
2.48.1