zonefs: convert zonefs to use the new mount api

Convert the zonefs filesystem to use the new mount API.
Tested using the zonefs test suite from:
https://github.com/damien-lemoal/zonefs-tools

Signed-off-by: Bill O'Donnell <bodonnel@redhat.com>
Reviewed-by: Ian Kent <raven@themaw.net>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>

Author: Bill O'Donnell

fs/zonefs/super.c

@@ -15,12 +15,13 @@
 #include <linux/writeback.h>
 #include <linux/quotaops.h>
 #include <linux/seq_file.h>
-#include <linux/parser.h>
 #include <linux/uio.h>
 #include <linux/mman.h>
 #include <linux/sched/mm.h>
 #include <linux/crc32.h>
 #include <linux/task_io_accounting_ops.h>
+#include <linux/fs_parser.h>
+#include <linux/fs_context.h>
 
 #include "zonefs.h"
 
@@ -460,58 +461,47 @@ static int zonefs_statfs(struct dentry *dentry, struct kstatfs *buf)
 }
 
 enum {
-	Opt_errors_ro, Opt_errors_zro, Opt_errors_zol, Opt_errors_repair,
-	Opt_explicit_open, Opt_err,
+	Opt_errors, Opt_explicit_open,
 };
 
-static const match_table_t tokens = {
-	{ Opt_errors_ro,	"errors=remount-ro"},
-	{ Opt_errors_zro,	"errors=zone-ro"},
-	{ Opt_errors_zol,	"errors=zone-offline"},
-	{ Opt_errors_repair,	"errors=repair"},
-	{ Opt_explicit_open,	"explicit-open" },
-	{ Opt_err,		NULL}
+struct zonefs_context {
+	unsigned long s_mount_opts;
 };
 
-static int zonefs_parse_options(struct super_block *sb, char *options)
-{
-	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
-	substring_t args[MAX_OPT_ARGS];
-	char *p;
-
-	if (!options)
-		return 0;
-
-	while ((p = strsep(&options, ",")) != NULL) {
-		int token;
+static const struct constant_table zonefs_param_errors[] = {
+	{"remount-ro",		ZONEFS_MNTOPT_ERRORS_RO},
+	{"zone-ro",		ZONEFS_MNTOPT_ERRORS_ZRO},
+	{"zone-offline",	ZONEFS_MNTOPT_ERRORS_ZOL},
+	{"repair", 		ZONEFS_MNTOPT_ERRORS_REPAIR},
+	{}
+};
 
-		if (!*p)
-			continue;
+static const struct fs_parameter_spec zonefs_param_spec[] = {
+	fsparam_enum	("errors",		Opt_errors, zonefs_param_errors),
+	fsparam_flag	("explicit-open",	Opt_explicit_open),
+	{}
+};
 
-		token = match_token(p, tokens, args);
-		switch (token) {
-		case Opt_errors_ro:
-			sbi->s_mount_opts &= ~ZONEFS_MNTOPT_ERRORS_MASK;
-			sbi->s_mount_opts |= ZONEFS_MNTOPT_ERRORS_RO;
-			break;
-		case Opt_errors_zro:
-			sbi->s_mount_opts &= ~ZONEFS_MNTOPT_ERRORS_MASK;
-			sbi->s_mount_opts |= ZONEFS_MNTOPT_ERRORS_ZRO;
-			break;
-		case Opt_errors_zol:
-			sbi->s_mount_opts &= ~ZONEFS_MNTOPT_ERRORS_MASK;
-			sbi->s_mount_opts |= ZONEFS_MNTOPT_ERRORS_ZOL;
-			break;
-		case Opt_errors_repair:
-			sbi->s_mount_opts &= ~ZONEFS_MNTOPT_ERRORS_MASK;
-			sbi->s_mount_opts |= ZONEFS_MNTOPT_ERRORS_REPAIR;
-			break;
-		case Opt_explicit_open:
-			sbi->s_mount_opts |= ZONEFS_MNTOPT_EXPLICIT_OPEN;
-			break;
-		default:
-			return -EINVAL;
-		}
+static int zonefs_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+	struct zonefs_context *ctx = fc->fs_private;
+	struct fs_parse_result result;
+	int opt;
+
+	opt = fs_parse(fc, zonefs_param_spec, param, &result);
+	if (opt < 0)
+		return opt;
+
+	switch (opt) {
+	case Opt_errors:
+		ctx->s_mount_opts &= ~ZONEFS_MNTOPT_ERRORS_MASK;
+		ctx->s_mount_opts |= result.uint_32;
+		break;
+	case Opt_explicit_open:
+		ctx->s_mount_opts |= ZONEFS_MNTOPT_EXPLICIT_OPEN;
+		break;
+	default:
+		return -EINVAL;
 	}
 
 	return 0;
@@ -533,13 +523,6 @@ static int zonefs_show_options(struct seq_file *seq, struct dentry *root)
 	return 0;
 }
 
-static int zonefs_remount(struct super_block *sb, int *flags, char *data)
-{
-	sync_filesystem(sb);
-
-	return zonefs_parse_options(sb, data);
-}
-
 static int zonefs_inode_setattr(struct mnt_idmap *idmap,
 				struct dentry *dentry, struct iattr *iattr)
 {
@@ -1195,7 +1178,6 @@ static const struct super_operations zonefs_sops = {
 	.alloc_inode	= zonefs_alloc_inode,
 	.free_inode	= zonefs_free_inode,
 	.statfs		= zonefs_statfs,
-	.remount_fs	= zonefs_remount,
 	.show_options	= zonefs_show_options,
 };
 
@@ -1240,9 +1222,10 @@ static void zonefs_release_zgroup_inodes(struct super_block *sb)
  * sub-directories and files according to the device zone configuration and
  * format options.
  */
-static int zonefs_fill_super(struct super_block *sb, void *data, int silent)
+static int zonefs_fill_super(struct super_block *sb, struct fs_context *fc)
 {
 	struct zonefs_sb_info *sbi;
+	struct zonefs_context *ctx = fc->fs_private;
 	struct inode *inode;
 	enum zonefs_ztype ztype;
 	int ret;
@@ -1279,7 +1262,7 @@ static int zonefs_fill_super(struct super_block *sb, void *data, int silent)
 	sbi->s_uid = GLOBAL_ROOT_UID;
 	sbi->s_gid = GLOBAL_ROOT_GID;
 	sbi->s_perm = 0640;
-	sbi->s_mount_opts = ZONEFS_MNTOPT_ERRORS_RO;
+	sbi->s_mount_opts = ctx->s_mount_opts;
 
 	atomic_set(&sbi->s_wro_seq_files, 0);
 	sbi->s_max_wro_seq_files = bdev_max_open_zones(sb->s_bdev);
@@ -1290,10 +1273,6 @@ static int zonefs_fill_super(struct super_block *sb, void *data, int silent)
 	if (ret)
 		return ret;
 
-	ret = zonefs_parse_options(sb, data);
-	if (ret)
-		return ret;
-
 	zonefs_info(sb, "Mounting %u zones", bdev_nr_zones(sb->s_bdev));
 
 	if (!sbi->s_max_wro_seq_files &&
@@ -1354,12 +1333,6 @@ static int zonefs_fill_super(struct super_block *sb, void *data, int silent)
 	return ret;
 }
 
-static struct dentry *zonefs_mount(struct file_system_type *fs_type,
-				   int flags, const char *dev_name, void *data)
-{
-	return mount_bdev(fs_type, flags, dev_name, data, zonefs_fill_super);
-}
-
 static void zonefs_kill_super(struct super_block *sb)
 {
 	struct zonefs_sb_info *sbi = ZONEFS_SB(sb);
@@ -1374,15 +1347,65 @@ static void zonefs_kill_super(struct super_block *sb)
 	kfree(sbi);
 }
 
+static void zonefs_free_fc(struct fs_context *fc)
+{
+	struct zonefs_context *ctx = fc->fs_private;
+
+	kfree(ctx);
+}
+
+static int zonefs_get_tree(struct fs_context *fc)
+{
+	return get_tree_bdev(fc, zonefs_fill_super);
+}
+
+static int zonefs_reconfigure(struct fs_context *fc)
+{
+	struct zonefs_context *ctx = fc->fs_private;
+	struct super_block *sb = fc->root->d_sb;
+	struct zonefs_sb_info *sbi = sb->s_fs_info;
+
+	sync_filesystem(fc->root->d_sb);
+	/* Copy new options from ctx into sbi. */
+	sbi->s_mount_opts = ctx->s_mount_opts;
+
+	return 0;
+}
+
+static const struct fs_context_operations zonefs_context_ops = {
+	.parse_param    = zonefs_parse_param,
+	.get_tree       = zonefs_get_tree,
+	.reconfigure	= zonefs_reconfigure,
+	.free           = zonefs_free_fc,
+};
+
+/*
+ * Set up the filesystem mount context.
+ */
+static int zonefs_init_fs_context(struct fs_context *fc)
+{
+	struct zonefs_context *ctx;
+
+	ctx = kzalloc(sizeof(struct zonefs_context), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+	ctx->s_mount_opts = ZONEFS_MNTOPT_ERRORS_RO;
+	fc->ops = &zonefs_context_ops;
+	fc->fs_private = ctx;
+
+	return 0;
+}
+
 /*
  * File system definition and registration.
  */
 static struct file_system_type zonefs_type = {
-	.owner		= THIS_MODULE,
-	.name		= "zonefs",
-	.mount		= zonefs_mount,
-	.kill_sb	= zonefs_kill_super,
-	.fs_flags	= FS_REQUIRES_DEV,
+	.owner			= THIS_MODULE,
+	.name			= "zonefs",
+	.kill_sb		= zonefs_kill_super,
+	.fs_flags		= FS_REQUIRES_DEV,
+	.init_fs_context	= zonefs_init_fs_context,
+	.parameters		= zonefs_param_spec,
 };
 
 static int __init zonefs_init_inodecache(void)