[for-6.11 PATCH 21/29] nfs_common: add NFS v3 LOCALIO protocol extension enablement

[Mike Snitzer <snitzer@kernel.org>]

First use is in nfsd, to add access to a global nfsd_uuids list that
will be used to identify local nfsd instances.

nfsd_uuids is protected by nfsd_mutex or RCU read lock.  List is
composed of nfsd_uuid_t instances that are managed as nfsd creates
them (per network namespace).

nfsd_uuid_is_local() will be used to search all local nfsd for the
client specified nfsd uuid.

Also, nfs and nfsd will only build their respective localio.c if
NFS_V3_LOCALIO and/or NFSD_V3_LOCALIO are enabled.

Signed-off-by: Mike Snitzer <snitzer@kernel.org>
---
 fs/Kconfig                 |  3 +++
 fs/nfs/Kconfig             | 13 ++++++++++++
 fs/nfs/Makefile            |  3 ++-
 fs/nfs/internal.h          | 38 ++++++++++++++++++++++++++++++++++
 fs/nfs_common/Makefile     |  3 +++
 fs/nfs_common/nfslocalio.c | 42 ++++++++++++++++++++++++++++++++++++++
 fs/nfsd/Kconfig            | 13 ++++++++++++
 fs/nfsd/Makefile           |  3 ++-
 fs/nfsd/netns.h            |  4 ++++
 fs/nfsd/nfssvc.c           | 11 ++++++++++
 include/linux/nfslocalio.h | 29 ++++++++++++++++++++++++++
 11 files changed, 160 insertions(+), 2 deletions(-)
 create mode 100644 fs/nfs_common/nfslocalio.c
 create mode 100644 include/linux/nfslocalio.h

diff --git a/fs/Kconfig b/fs/Kconfig
index a46b0cbc4d8f..9864a738ccae 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -377,6 +377,9 @@ config NFS_ACL_SUPPORT
 	tristate
 	select FS_POSIX_ACL
 
+config NFS_LOCALIO_SUPPORT
+	tristate
+
 config NFS_COMMON
 	bool
 	depends on NFSD || NFS_FS || LOCKD
diff --git a/fs/nfs/Kconfig b/fs/nfs/Kconfig
index 57249f040dfc..db8c9d6edcea 100644
--- a/fs/nfs/Kconfig
+++ b/fs/nfs/Kconfig
@@ -5,6 +5,7 @@ config NFS_FS
 	select LOCKD
 	select SUNRPC
 	select NFS_ACL_SUPPORT if NFS_V3_ACL
+	select NFS_LOCALIO_SUPPORT if NFS_V3_LOCALIO
 	help
 	  Choose Y here if you want to access files residing on other
 	  computers using Sun's Network File System protocol.  To compile
@@ -72,6 +73,18 @@ config NFS_V3_ACL
 
 	  If unsure, say N.
 
+config NFS_V3_LOCALIO
+	bool "NFS client support for the NFSv3 LOCALIO protocol extension"
+	depends on NFS_V3
+	help
+	  Some NFS servers support an auxiliary NFSv3 LOCALIO protocol
+	  that is not an official part of the NFS version 3 protocol.
+
+	  This option enables support for version 3 of the LOCALIO
+	  protocol in the kernel's NFS client.
+
+	  If unsure, say N.
+
 config NFS_V4
 	tristate "NFS client support for NFS version 4"
 	depends on NFS_FS
diff --git a/fs/nfs/Makefile b/fs/nfs/Makefile
index af64cf5ea420..7fed1ce375da 100644
--- a/fs/nfs/Makefile
+++ b/fs/nfs/Makefile
@@ -9,10 +9,11 @@ CFLAGS_nfstrace.o += -I$(src)
 nfs-y 			:= client.o dir.o file.o getroot.o inode.o super.o \
 			   io.o direct.o pagelist.o read.o symlink.o unlink.o \
 			   write.o namespace.o mount_clnt.o nfstrace.o \
-			   export.o sysfs.o fs_context.o localio.o
+			   export.o sysfs.o fs_context.o
 nfs-$(CONFIG_ROOT_NFS)	+= nfsroot.o
 nfs-$(CONFIG_SYSCTL)	+= sysctl.o
 nfs-$(CONFIG_NFS_FSCACHE) += fscache.o
+nfs-$(CONFIG_NFS_V3_LOCALIO) += localio.o
 
 obj-$(CONFIG_NFS_V2) += nfsv2.o
 nfsv2-y := nfs2super.o proc.o nfs2xdr.o
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 6d75466ad356..9f81a94e798c 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -452,6 +452,7 @@ extern void nfs_set_cache_invalid(struct inode *inode, unsigned long flags);
 extern bool nfs_check_cache_invalid(struct inode *, unsigned long);
 extern int nfs_wait_bit_killable(struct wait_bit_key *key, int mode);
 
+#if defined(CONFIG_NFS_V3_LOCALIO)
 /* localio.c */
 extern void nfs_local_init(void);
 extern void nfs_local_enable(struct nfs_client *);
@@ -471,6 +472,43 @@ extern int nfs_local_commit(struct nfs_client *, struct file *,
 			    const struct rpc_call_ops *, int);
 extern bool nfs_server_is_local(const struct nfs_client *clp);
 
+#else
+static inline void nfs_local_init(void) {}
+static inline void nfs_local_enable(struct nfs_client *clp) {}
+static inline void nfs_local_disable(struct nfs_client *clp) {}
+static inline void nfs_local_probe(struct nfs_client *clp) {}
+static inline struct file *nfs_local_open_fh(struct nfs_client *clp,
+					const struct cred *cred,
+					struct nfs_fh *fh,
+					const fmode_t mode)
+{
+	return ERR_PTR(-EINVAL);
+}
+static inline struct file *nfs_local_file_open(struct nfs_client *clp,
+					const struct cred *cred,
+					struct nfs_fh *fh,
+					struct nfs_open_context *ctx)
+{
+	return NULL;
+}
+static inline int nfs_local_doio(struct nfs_client *clp, struct file *filep,
+				struct nfs_pgio_header *hdr,
+				const struct rpc_call_ops *call_ops)
+{
+	return -EINVAL;
+}
+static inline int nfs_local_commit(struct nfs_client *clp, struct file *filep,
+				struct nfs_commit_data *data,
+				const struct rpc_call_ops *call_ops, int how)
+{
+	return -EINVAL;
+}
+static inline bool nfs_server_is_local(const struct nfs_client *clp)
+{
+	return false;
+}
+#endif /* CONFIG_NFS_V3_LOCALIO */
+
 /* super.c */
 extern const struct super_operations nfs_sops;
 bool nfs_auth_info_match(const struct nfs_auth_info *, rpc_authflavor_t);
diff --git a/fs/nfs_common/Makefile b/fs/nfs_common/Makefile
index 119c75ab9fd0..c566cca92a1b 100644
--- a/fs/nfs_common/Makefile
+++ b/fs/nfs_common/Makefile
@@ -6,5 +6,8 @@
 obj-$(CONFIG_NFS_ACL_SUPPORT) += nfs_acl.o
 nfs_acl-objs := nfsacl.o
 
+obj-$(CONFIG_NFS_LOCALIO_SUPPORT) += nfs_localio.o
+nfs_localio-objs := nfslocalio.o
+
 obj-$(CONFIG_GRACE_PERIOD) += grace.o
 obj-$(CONFIG_NFS_V4_2_SSC_HELPER) += nfs_ssc.o
diff --git a/fs/nfs_common/nfslocalio.c b/fs/nfs_common/nfslocalio.c
new file mode 100644
index 000000000000..f214cc6754a1
--- /dev/null
+++ b/fs/nfs_common/nfslocalio.c
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2024 Mike Snitzer <snitzer@hammerspace.com>
+ */
+
+#include <linux/module.h>
+#include <linux/rculist.h>
+#include <linux/nfslocalio.h>
+
+MODULE_LICENSE("GPL");
+
+/*
+ * Global list of nfsd_uuid_t instances, add/remove
+ * is protected by fs/nfsd/nfssvc.c:nfsd_mutex.
+ * Reads are protected RCU read lock (see below).
+ */
+LIST_HEAD(nfsd_uuids);
+EXPORT_SYMBOL(nfsd_uuids);
+
+/* Must be called with RCU read lock held. */
+static const uuid_t * nfsd_uuid_lookup(const uuid_t *uuid)
+{
+	nfsd_uuid_t *nfsd_uuid;
+
+	list_for_each_entry_rcu(nfsd_uuid, &nfsd_uuids, list)
+		if (uuid_equal(&nfsd_uuid->uuid, uuid))
+			return &nfsd_uuid->uuid;
+
+	return &uuid_null;
+}
+
+bool nfsd_uuid_is_local(const uuid_t *uuid)
+{
+	const uuid_t *nfsd_uuid;
+
+	rcu_read_lock();
+	nfsd_uuid = nfsd_uuid_lookup(uuid);
+	rcu_read_unlock();
+
+	return !uuid_is_null(nfsd_uuid);
+}
+EXPORT_SYMBOL_GPL(nfsd_uuid_is_local);
diff --git a/fs/nfsd/Kconfig b/fs/nfsd/Kconfig
index 272ab8d5c4d7..c8eb7e2d4006 100644
--- a/fs/nfsd/Kconfig
+++ b/fs/nfsd/Kconfig
@@ -9,6 +9,7 @@ config NFSD
 	select EXPORTFS
 	select NFS_ACL_SUPPORT if NFSD_V2_ACL
 	select NFS_ACL_SUPPORT if NFSD_V3_ACL
+	select NFS_LOCALIO_SUPPORT if NFSD_V3_LOCALIO
 	depends on MULTIUSER
 	help
 	  Choose Y here if you want to allow other computers to access
@@ -69,6 +70,18 @@ config NFSD_V3_ACL
 
 	  If unsure, say N.
 
+config NFSD_V3_LOCALIO
+	bool "NFS server support for the NFSv3 LOCALIO protocol extension"
+	depends on NFSD
+	help
+	  Some NFS servers support an auxiliary NFSv3 LOCALIO protocol
+	  that is not an official part of the NFS version 3 protocol.
+
+	  This option enables support for version 3 of the LOCALIO
+	  protocol in the kernel's NFS server.
+
+	  If unsure, say N.
+
 config NFSD_V4
 	bool "NFS server support for NFS version 4"
 	depends on NFSD && PROC_FS
diff --git a/fs/nfsd/Makefile b/fs/nfsd/Makefile
index 702f277394f1..0e01749f6153 100644
--- a/fs/nfsd/Makefile
+++ b/fs/nfsd/Makefile
@@ -13,7 +13,7 @@ nfsd-y			+= trace.o
 nfsd-y 			+= nfssvc.o nfsctl.o nfsfh.o vfs.o \
 			   export.o auth.o lockd.o nfscache.o \
 			   stats.o filecache.o nfs3proc.o nfs3xdr.o \
-			   netlink.o localio.o
+			   netlink.o
 nfsd-$(CONFIG_NFSD_V2) += nfsproc.o nfsxdr.o
 nfsd-$(CONFIG_NFSD_V2_ACL) += nfs2acl.o
 nfsd-$(CONFIG_NFSD_V3_ACL) += nfs3acl.o
@@ -23,3 +23,4 @@ nfsd-$(CONFIG_NFSD_PNFS) += nfs4layouts.o
 nfsd-$(CONFIG_NFSD_BLOCKLAYOUT) += blocklayout.o blocklayoutxdr.o
 nfsd-$(CONFIG_NFSD_SCSILAYOUT) += blocklayout.o blocklayoutxdr.o
 nfsd-$(CONFIG_NFSD_FLEXFILELAYOUT) += flexfilelayout.o flexfilelayoutxdr.o
+nfsd-$(CONFIG_NFSD_V3_LOCALIO) += localio.o
diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h
index 14ec15656320..5c5f7030ad87 100644
--- a/fs/nfsd/netns.h
+++ b/fs/nfsd/netns.h
@@ -15,6 +15,7 @@
 #include <linux/percpu_counter.h>
 #include <linux/siphash.h>
 #include <linux/sunrpc/stats.h>
+#include <linux/nfslocalio.h>
 
 /* Hash tables for nfs4_clientid state */
 #define CLIENT_HASH_BITS                 4
@@ -213,6 +214,9 @@ struct nfsd_net {
 	/* last time an admin-revoke happened for NFSv4.0 */
 	time64_t		nfs40_last_revoke;
 
+#if defined(CONFIG_NFSD_V3_LOCALIO)
+	nfsd_uuid_t		nfsd_uuid;
+#endif
 };
 
 /* Simple check to find out if a given net was properly initialized */
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index cd9a6a1a9fc8..122cfa184805 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -19,6 +19,7 @@
 #include <linux/sunrpc/svc_xprt.h>
 #include <linux/lockd/bind.h>
 #include <linux/nfsacl.h>
+#include <linux/nfslocalio.h>
 #include <linux/seq_file.h>
 #include <linux/inetdevice.h>
 #include <net/addrconf.h>
@@ -427,6 +428,10 @@ static int nfsd_startup_net(struct net *net, const struct cred *cred)
 
 #ifdef CONFIG_NFSD_V4_2_INTER_SSC
 	nfsd4_ssc_init_umount_work(nn);
+#endif
+#if defined(CONFIG_NFSD_V3_LOCALIO)
+	INIT_LIST_HEAD(&nn->nfsd_uuid.list);
+	list_add_tail_rcu(&nn->nfsd_uuid.list, &nfsd_uuids);
 #endif
 	nn->nfsd_net_up = true;
 	return 0;
@@ -457,6 +462,9 @@ static void nfsd_shutdown_net(struct net *net)
 		nn->lockd_up = false;
 	}
 	nn->nfsd_net_up = false;
+#if defined(CONFIG_NFSD_V3_LOCALIO)
+	list_del_rcu(&nn->nfsd_uuid.list);
+#endif
 	nfsd_shutdown_generic();
 }
 
@@ -787,6 +795,9 @@ nfsd_svc(int nrservs, struct net *net, const struct cred *cred, const char *scop
 
 	strscpy(nn->nfsd_name, scope ? scope : utsname()->nodename,
 		sizeof(nn->nfsd_name));
+#if defined(CONFIG_NFSD_V3_LOCALIO)
+	uuid_gen(&nn->nfsd_uuid.uuid);
+#endif
 
 	error = nfsd_create_serv(net);
 	if (error)
diff --git a/include/linux/nfslocalio.h b/include/linux/nfslocalio.h
new file mode 100644
index 000000000000..d0bbacd0adcf
--- /dev/null
+++ b/include/linux/nfslocalio.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2024 Mike Snitzer <snitzer@hammerspace.com>
+ */
+#ifndef __LINUX_NFSLOCALIO_H
+#define __LINUX_NFSLOCALIO_H
+
+#include <linux/list.h>
+#include <linux/uuid.h>
+
+/*
+ * Global list of nfsd_uuid_t instances, add/remove
+ * is protected by fs/nfsd/nfssvc.c:nfsd_mutex.
+ */
+extern struct list_head nfsd_uuids;
+
+/*
+ * Each nfsd instance has an nfsd_uuid_t that is accessible through the
+ * global nfsd_uuids list. Useful to allow a client to negotiate if localio
+ * possible with its server.
+ */
+typedef struct {
+	uuid_t uuid;
+	struct list_head list;
+} nfsd_uuid_t;
+
+bool nfsd_uuid_is_local(const uuid_t *uuid);
+
+#endif  /* __LINUX_NFSLOCALIO_H */
-- 
2.44.0