From: Olga Kornievskaia <kolga@netapp.com>
Date: Wed, 16 Mar 2022 18:24:26 -0400
Subject: [PATCH] NFSv4.1 provide mount option to toggle trunking discovery
Git-commit: a43bf604446414103b7535f38e739b65601c4fb2
Patch-mainline: v5.18
References: git-fixes

Introduce a new mount option -- trunkdiscovery,notrunkdiscovery -- to
toggle whether or not the client will engage in actively discovery
of trunking locations.

v2 make notrunkdiscovery default

Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Fixes: 1976b2b31462 ("NFSv4.1 query for fs_location attr on a new file system")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Acked-by: NeilBrown <neilb@suse.com>

---
 fs/nfs/client.c           |    3 ++-
 fs/nfs/fs_context.c       |    8 ++++++++
 include/linux/nfs_fs_sb.h |    1 +
 3 files changed, 11 insertions(+), 1 deletion(-)

--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -859,7 +859,8 @@ int nfs_probe_fsinfo(struct nfs_server *
 	}
 
 	if (clp->rpc_ops->discover_trunking != NULL &&
-			(server->caps & NFS_CAP_FS_LOCATIONS)) {
+			(server->caps & NFS_CAP_FS_LOCATIONS &&
+			 (server->flags & NFS_MOUNT_TRUNK_DISCOVERY))) {
 		error = clp->rpc_ops->discover_trunking(server, mntfh);
 		if (error < 0)
 			return error;
--- a/fs/nfs/fs_context.c
+++ b/fs/nfs/fs_context.c
@@ -78,6 +78,7 @@ enum nfs_param {
 	Opt_source,
 	Opt_tcp,
 	Opt_timeo,
+	Opt_trunkdiscovery,
 	Opt_udp,
 	Opt_v,
 	Opt_vers,
@@ -177,6 +178,7 @@ static const struct fs_parameter_spec nf
 	fsparam_string("source",	Opt_source),
 	fsparam_flag  ("tcp",		Opt_tcp),
 	fsparam_u32   ("timeo",		Opt_timeo),
+	fsparam_flag_no("trunkdiscovery", Opt_trunkdiscovery),
 	fsparam_flag  ("udp",		Opt_udp),
 	fsparam_flag  ("v2",		Opt_v),
 	fsparam_flag  ("v3",		Opt_v),
@@ -526,6 +528,12 @@ static int nfs_fs_context_parse_param(st
 		else
 			ctx->flags &= ~NFS_MOUNT_NOCTO;
 		break;
+	case Opt_trunkdiscovery:
+		if (result.negated)
+			ctx->flags &= ~NFS_MOUNT_TRUNK_DISCOVERY;
+		else
+			ctx->flags |= NFS_MOUNT_TRUNK_DISCOVERY;
+		break;
 	case Opt_ac:
 		if (result.negated)
 			ctx->flags |= NFS_MOUNT_NOAC;
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -155,6 +155,7 @@ struct nfs_server {
 #define NFS_MOUNT_SOFTREVAL		0x800000
 #define NFS_MOUNT_WRITE_EAGER		0x01000000
 #define NFS_MOUNT_WRITE_WAIT		0x02000000
+#define NFS_MOUNT_TRUNK_DISCOVERY	0x04000000
 
 	unsigned int		fattr_valid;	/* Valid attributes */
 	unsigned int		caps;		/* server capabilities */