zfs label bootenv should store data as nvlist

nvlist does allow us to support different data types and systems.

To encapsulate user data to/from nvlist, the libzfsbootenv library is
provided.

Reviewed-by: Arvind Sankar <nivedita@alum.mit.edu>
Reviewed-by: Allan Jude <allan@klarasystems.com>
Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Reviewed-by: Igor Kozhukhov <igor@dilos.org>
Signed-off-by: Toomas Soome <tsoome@me.com>
Closes #10774

include/Makefile.am

@@ -15,6 +15,7 @@ USER_H = \
 	libuutil.h \
 	libuutil_impl.h \
 	libzfs.h \
+	libzfsbootenv.h \
 	libzfs_core.h \
 	libzfs_impl.h \
 	libzutil.h \

include/libzfs.h

@@ -892,8 +892,8 @@ extern int zpool_in_use(libzfs_handle_t *, int, pool_state_t *, char **,
  * Label manipulation.
  */
 extern int zpool_clear_label(int);
-extern int zpool_set_bootenv(zpool_handle_t *, const char *);
-extern int zpool_get_bootenv(zpool_handle_t *, char *, size_t, off_t);
+extern int zpool_set_bootenv(zpool_handle_t *, const nvlist_t *);
+extern int zpool_get_bootenv(zpool_handle_t *, nvlist_t **);
 
 /*
  * Management interfaces for SMB ACL files

include/libzfs_core.h

@@ -135,7 +135,7 @@ int lzc_wait(const char *, zpool_wait_activity_t, boolean_t *);
 int lzc_wait_tag(const char *, zpool_wait_activity_t, uint64_t, boolean_t *);
 int lzc_wait_fs(const char *, zfs_wait_activity_t, boolean_t *);
 
-int lzc_set_bootenv(const char *, const char *);
+int lzc_set_bootenv(const char *, const nvlist_t *);
 int lzc_get_bootenv(const char *, nvlist_t **);
 #ifdef	__cplusplus
 }

include/libzfsbootenv.h

@@ -0,0 +1,41 @@
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source.  A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * Copyright 2020 Toomas Soome <tsoome@me.com>
+ */
+
+#ifndef _LIBZFSBOOTENV_H
+#define	_LIBZFSBOOTENV_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef enum lzbe_flags {
+	lzbe_add,	/* add data to existing nvlist */
+	lzbe_replace	/* replace current nvlist */
+} lzbe_flags_t;
+
+extern int lzbe_nvlist_get(const char *, const char *, void **);
+extern int lzbe_nvlist_set(const char *, const char *, void *);
+extern void lzbe_nvlist_free(void *);
+extern int lzbe_add_pair(void *, const char *, const char *, void *, size_t);
+extern int lzbe_remove_pair(void *, const char *);
+extern int lzbe_set_boot_device(const char *, lzbe_flags_t, const char *);
+extern int lzbe_get_boot_device(const char *, char **);
+extern int lzbe_bootenv_print(const char *, const char *, FILE *);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _LIBZFSBOOTENV_H */

include/os/freebsd/zfs/sys/Makefile.am

@@ -2,6 +2,7 @@ KERNEL_H = \
 	freebsd_crypto.h \
 	sha2.h \
 	vdev_os.h \
+	zfs_bootenv_os.h \
 	zfs_context_os.h \
 	zfs_ctldir.h \
 	zfs_dir.h \

include/os/freebsd/zfs/sys/zfs_bootenv_os.h

@@ -0,0 +1,29 @@
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source.  A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * Copyright 2020 Toomas Soome <tsoome@me.com>
+ */
+
+#ifndef _ZFS_BOOTENV_OS_H
+#define	_ZFS_BOOTENV_OS_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define	BOOTENV_OS		BE_FREEBSD_VENDOR
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _ZFS_BOOTENV_OS_H */

include/os/linux/zfs/sys/Makefile.am

@@ -16,6 +16,7 @@ KERNEL_H = \
 	trace_zil.h \
 	trace_zio.h \
 	trace_zrlock.h \
+	zfs_bootenv_os.h \
 	zfs_context_os.h \
 	zfs_ctldir.h \
 	zfs_dir.h \

include/os/linux/zfs/sys/zfs_bootenv_os.h

@@ -0,0 +1,29 @@
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source.  A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * Copyright 2020 Toomas Soome <tsoome@me.com>
+ */
+
+#ifndef _ZFS_BOOTENV_OS_H
+#define	_ZFS_BOOTENV_OS_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define	BOOTENV_OS		BE_LINUX_VENDOR
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _ZFS_BOOTENV_OS_H */

include/sys/Makefile.am

@@ -102,6 +102,7 @@ COMMON_H = \
 	zcp_set.h \
 	zfeature.h \
 	zfs_acl.h \
+	zfs_bootenv.h \
 	zfs_context.h \
 	zfs_debug.h \
 	zfs_delay.h \

include/sys/fs/zfs.h

@@ -1336,8 +1336,8 @@ typedef enum zfs_ioc {
 	ZFS_IOC_NEXTBOOT,			/* 0x84 (FreeBSD) */
 	ZFS_IOC_JAIL,				/* 0x85 (FreeBSD) */
 	ZFS_IOC_UNJAIL,				/* 0x86 (FreeBSD) */
-	ZFS_IOC_SET_BOOTENV,			/* 0x87 (Linux) */
-	ZFS_IOC_GET_BOOTENV,			/* 0x88 (Linux) */
+	ZFS_IOC_SET_BOOTENV,			/* 0x87 */
+	ZFS_IOC_GET_BOOTENV,			/* 0x88 */
 	ZFS_IOC_LAST
 } zfs_ioc_t;
 

include/sys/vdev.h

@@ -181,7 +181,7 @@ extern void vdev_config_generate_stats(vdev_t *vd, nvlist_t *nv);
 extern void vdev_label_write(zio_t *zio, vdev_t *vd, int l, abd_t *buf, uint64_t
     offset, uint64_t size, zio_done_func_t *done, void *priv, int flags);
 extern int vdev_label_read_bootenv(vdev_t *, nvlist_t *);
-extern int vdev_label_write_bootenv(vdev_t *, char *);
+extern int vdev_label_write_bootenv(vdev_t *, nvlist_t *);
 
 typedef enum {
 	VDEV_LABEL_CREATE,	/* create/add a new device */

include/sys/vdev_impl.h

@@ -476,7 +476,16 @@ typedef struct vdev_phys {
 } vdev_phys_t;
 
 typedef enum vbe_vers {
-	/* The bootenv file is stored as ascii text in the envblock */
+	/*
+	 * The bootenv file is stored as ascii text in the envblock.
+	 * It is used by the GRUB bootloader used on Linux to store the
+	 * contents of the grubenv file. The file is stored as raw ASCII,
+	 * and is protected by an embedded checksum. By default, GRUB will
+	 * check if the boot filesystem supports storing the environment data
+	 * in a special location, and if so, will invoke filesystem specific
+	 * logic to retrieve it. This can be overriden by a variable, should
+	 * the user so desire.
+	 */
 	VB_RAW = 0,
 
 	/*

include/sys/zfs_bootenv.h

@@ -0,0 +1,53 @@
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source.  A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * Copyright 2020 Toomas Soome <tsoome@me.com>
+ */
+
+#ifndef _ZFS_BOOTENV_H
+#define	_ZFS_BOOTENV_H
+
+/*
+ * Define macros for label bootenv nvlist pair keys.
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define	BOOTENV_VERSION		"version"
+
+#define	BE_ILLUMOS_VENDOR	"illumos"
+#define	BE_FREEBSD_VENDOR	"freebsd"
+#define	BE_GRUB_VENDOR		"grub"
+#define	BE_LINUX_VENDOR		"linux"
+
+#include <sys/zfs_bootenv_os.h>
+
+#define	GRUB_ENVMAP		BE_GRUB_VENDOR ":" "envmap"
+
+#define	FREEBSD_BOOTONCE	BE_FREEBSD_VENDOR ":" "bootonce"
+#define	FREEBSD_BOOTONCE_USED	BE_FREEBSD_VENDOR ":" "bootonce-used"
+#define	FREEBSD_NVSTORE		BE_FREEBSD_VENDOR ":" "nvstore"
+#define	ILLUMOS_BOOTONCE	BE_ILLUMOS_VENDOR ":" "bootonce"
+#define	ILLUMOS_BOOTONCE_USED	BE_ILLUMOS_VENDOR ":" "bootonce-used"
+#define	ILLUMOS_NVSTORE		BE_ILLUMOS_VENDOR ":" "nvstore"
+
+#define	OS_BOOTONCE		BOOTENV_OS ":" "bootonce"
+#define	OS_BOOTONCE_USED	BOOTENV_OS ":" "bootonce-used"
+#define	OS_NVSTORE		BOOTENV_OS ":" "nvstore"
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _ZFS_BOOTENV_H */