[PATCH 2/2] NFS: add a clientid mount option

[Christoph Hellwig <hch@lst.de>]

Add a mount option to set a clientid, similarly to how it can be
configured through the per-netfs sysfs file.  This allows for easy
testing of behavior that relies on the client ID likes locks or
delegations with having to resort to separate VMs or containers.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/nfs/client.c           | 12 ++++++++++++
 fs/nfs/fs_context.c       | 12 ++++++++++++
 fs/nfs/internal.h         |  2 ++
 fs/nfs/nfs4client.c       |  1 +
 fs/nfs/nfs4proc.c         |  7 ++++++-
 include/linux/nfs_fs_sb.h |  1 +
 6 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 47258dc3af70..1a55debab6e5 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -181,6 +181,12 @@ struct nfs_client *nfs_alloc_client(const struct nfs_client_initdata *cl_init)
 	clp->cl_nconnect = cl_init->nconnect;
 	clp->cl_max_connect = cl_init->max_connect ? cl_init->max_connect : 1;
 	clp->cl_net = get_net_track(cl_init->net, &clp->cl_ns_tracker, GFP_KERNEL);
+	if (cl_init->clientid) {
+		err = -ENOMEM;
+		clp->clientid = kstrdup(cl_init->clientid, GFP_KERNEL);
+		if (!clp->clientid)
+			goto error_free_host;
+	}
 
 #if IS_ENABLED(CONFIG_NFS_LOCALIO)
 	seqlock_init(&clp->cl_boot_lock);
@@ -193,6 +199,8 @@ struct nfs_client *nfs_alloc_client(const struct nfs_client_initdata *cl_init)
 	clp->cl_xprtsec = cl_init->xprtsec;
 	return clp;
 
+error_free_host:
+	kfree(clp->cl_hostname);
 error_cleanup:
 	put_nfs_version(clp->cl_nfs_mod);
 error_dealloc:
@@ -254,6 +262,7 @@ void nfs_free_client(struct nfs_client *clp)
 	put_nfs_version(clp->cl_nfs_mod);
 	kfree(clp->cl_hostname);
 	kfree(clp->cl_acceptor);
+	kfree(clp->clientid);
 	kfree_rcu(clp, rcu);
 }
 EXPORT_SYMBOL_GPL(nfs_free_client);
@@ -339,6 +348,9 @@ static struct nfs_client *nfs_match_client(const struct nfs_client_initdata *dat
 		if (clp->cl_xprtsec.policy != data->xprtsec.policy)
 			continue;
 
+		if (data->clientid && data->clientid != clp->clientid)
+			continue;
+
 		refcount_inc(&clp->cl_count);
 		return clp;
 	}
diff --git a/fs/nfs/fs_context.c b/fs/nfs/fs_context.c
index 9e94d18448ff..fe9ecdc8db3c 100644
--- a/fs/nfs/fs_context.c
+++ b/fs/nfs/fs_context.c
@@ -98,6 +98,7 @@ enum nfs_param {
 	Opt_xprtsec,
 	Opt_cert_serial,
 	Opt_privkey_serial,
+	Opt_clientid,
 };
 
 enum {
@@ -225,6 +226,7 @@ static const struct fs_parameter_spec nfs_fs_parameters[] = {
 	fsparam_string("xprtsec",	Opt_xprtsec),
 	fsparam_s32("cert_serial",	Opt_cert_serial),
 	fsparam_s32("privkey_serial",	Opt_privkey_serial),
+	fsparam_string("clientid",	Opt_clientid),
 	{}
 };
 
@@ -1031,6 +1033,14 @@ static int nfs_fs_context_parse_param(struct fs_context *fc,
 			goto out_invalid_value;
 		}
 		break;
+	case Opt_clientid:
+		if (!param->string || strlen(param->string) == 0 ||
+		    strlen(param->string) > NFS4_CLIENT_ID_UNIQ_LEN - 1)
+			goto out_of_bounds;
+		kfree(ctx->clientid);
+		ctx->clientid = param->string;
+		param->string = NULL;
+		break;
 
 		/*
 		 * Special options
@@ -1650,6 +1660,7 @@ static int nfs_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc)
 	ctx->nfs_server.hostname	= NULL;
 	ctx->fscache_uniq		= NULL;
 	ctx->clone_data.fattr		= NULL;
+	ctx->clientid			= NULL;
 	fc->fs_private = ctx;
 	return 0;
 }
@@ -1670,6 +1681,7 @@ static void nfs_fs_context_free(struct fs_context *fc)
 		kfree(ctx->fscache_uniq);
 		nfs_free_fhandle(ctx->mntfh);
 		nfs_free_fattr(ctx->clone_data.fattr);
+		kfree(ctx->clientid);
 		kfree(ctx);
 	}
 }
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 69c2c10ee658..1a392676d27c 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -86,6 +86,7 @@ struct nfs_client_initdata {
 	struct xprtsec_parms xprtsec;
 	unsigned long connect_timeout;
 	unsigned long reconnect_timeout;
+	const char *clientid;
 };
 
 /*
@@ -115,6 +116,7 @@ struct nfs_fs_context {
 	unsigned short		mountfamily;
 	bool			has_sec_mnt_opts;
 	int			lock_status;
+	char			*clientid;
 
 	struct {
 		union {
diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index 2e623da1a787..3ab5cc985224 100644
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -1153,6 +1153,7 @@ static int nfs4_init_server(struct nfs_server *server, struct fs_context *fc)
 		.xprtsec = ctx->xprtsec,
 		.nconnect = ctx->nfs_server.nconnect,
 		.max_connect = ctx->nfs_server.max_connect,
+		.clientid = ctx->clientid,
 	};
 	int error;
 
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index ef2077e185b6..ad53bc4ef50c 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -6487,6 +6487,11 @@ nfs4_get_uniquifier(struct nfs_client *clp, char *buf, size_t buflen)
 
 	buf[0] = '\0';
 
+	if (clp->clientid) {
+		strscpy(buf, clp->clientid, buflen);
+		goto out;
+	}
+
 	if (nn_clp) {
 		rcu_read_lock();
 		id = rcu_dereference(nn_clp->identifier);
@@ -6497,7 +6502,7 @@ nfs4_get_uniquifier(struct nfs_client *clp, char *buf, size_t buflen)
 
 	if (nfs4_client_id_uniquifier[0] != '\0' && buf[0] == '\0')
 		strscpy(buf, nfs4_client_id_uniquifier, buflen);
-
+out:
 	return strlen(buf);
 }
 
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index d2d36711a119..73bed04529a7 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -128,6 +128,7 @@ struct nfs_client {
 	netns_tracker		cl_ns_tracker;
 	struct list_head	pending_cb_stateids;
 	struct rcu_head		rcu;
+	const char		*clientid;
 
 #if IS_ENABLED(CONFIG_NFS_LOCALIO)
 	struct timespec64	cl_nfssvc_boot;
-- 
2.47.2