efs: convert efs to use the new mount api

Convert the efs filesystem to use the new mount API.

Signed-off-by: Bill O'Donnell <bodonnel@redhat.com>
Link: https://lore.kernel.org/r/20240220003318.166143-1-bodonnel@redhat.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs/efs/super.c

@@ -14,19 +14,14 @@
 #include <linux/buffer_head.h>
 #include <linux/vfs.h>
 #include <linux/blkdev.h>
-
+#include <linux/fs_context.h>
+#include <linux/fs_parser.h>
 #include "efs.h"
 #include <linux/efs_vh.h>
 #include <linux/efs_fs_sb.h>
 
 static int efs_statfs(struct dentry *dentry, struct kstatfs *buf);
-static int efs_fill_super(struct super_block *s, void *d, int silent);
+static int efs_init_fs_context(struct fs_context *fc);
-
-static struct dentry *efs_mount(struct file_system_type *fs_type,
-	int flags, const char *dev_name, void *data)
-{
-	return mount_bdev(fs_type, flags, dev_name, data, efs_fill_super);
-}
 
 static void efs_kill_sb(struct super_block *s)
 {
@@ -35,15 +30,6 @@ static void efs_kill_sb(struct super_block *s)
 	kfree(sbi);
 }
 
-static struct file_system_type efs_fs_type = {
-	.owner		= THIS_MODULE,
-	.name		= "efs",
-	.mount		= efs_mount,
-	.kill_sb	= efs_kill_sb,
-	.fs_flags	= FS_REQUIRES_DEV,
-};
-MODULE_ALIAS_FS("efs");
-
 static struct pt_types sgi_pt_types[] = {
 	{0x00,		"SGI vh"},
 	{0x01,		"SGI trkrepl"},
@@ -63,6 +49,27 @@ static struct pt_types sgi_pt_types[] = {
 	{0,		NULL}
 };
 
+enum {
+	Opt_explicit_open,
+};
+
+static const struct fs_parameter_spec efs_param_spec[] = {
+	fsparam_flag    ("explicit-open",       Opt_explicit_open),
+	{}
+};
+
+/*
+ * File system definition and registration.
+ */
+static struct file_system_type efs_fs_type = {
+	.owner			= THIS_MODULE,
+	.name			= "efs",
+	.kill_sb		= efs_kill_sb,
+	.fs_flags		= FS_REQUIRES_DEV,
+	.init_fs_context	= efs_init_fs_context,
+	.parameters		= efs_param_spec,
+};
+MODULE_ALIAS_FS("efs");
 
 static struct kmem_cache * efs_inode_cachep;
 
@@ -108,18 +115,10 @@ static void destroy_inodecache(void)
 	kmem_cache_destroy(efs_inode_cachep);
 }
 
-static int efs_remount(struct super_block *sb, int *flags, char *data)
-{
-	sync_filesystem(sb);
-	*flags |= SB_RDONLY;
-	return 0;
-}
-
 static const struct super_operations efs_superblock_operations = {
 	.alloc_inode	= efs_alloc_inode,
 	.free_inode	= efs_free_inode,
 	.statfs		= efs_statfs,
-	.remount_fs	= efs_remount,
 };
 
 static const struct export_operations efs_export_ops = {
@@ -249,7 +248,7 @@ static int efs_validate_super(struct efs_sb_info *sb, struct efs_super *super) {
 	return 0;    
 }
 
-static int efs_fill_super(struct super_block *s, void *d, int silent)
+static int efs_fill_super(struct super_block *s, struct fs_context *fc)
 {
 	struct efs_sb_info *sb;
 	struct buffer_head *bh;
@@ -328,6 +327,61 @@ static int efs_fill_super(struct super_block *s, void *d, int silent)
 	return 0;
 }
 
+static void efs_free_fc(struct fs_context *fc)
+{
+	kfree(fc->fs_private);
+}
+
+static int efs_get_tree(struct fs_context *fc)
+{
+	return get_tree_bdev(fc, efs_fill_super);
+}
+
+static int efs_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+	int token;
+	struct fs_parse_result result;
+
+	token = fs_parse(fc, efs_param_spec, param, &result);
+	if (token < 0)
+		return token;
+	return 0;
+}
+
+static int efs_reconfigure(struct fs_context *fc)
+{
+	sync_filesystem(fc->root->d_sb);
+
+	return 0;
+}
+
+struct efs_context {
+	unsigned long s_mount_opts;
+};
+
+static const struct fs_context_operations efs_context_opts = {
+	.parse_param	= efs_parse_param,
+	.get_tree	= efs_get_tree,
+	.reconfigure	= efs_reconfigure,
+	.free		= efs_free_fc,
+};
+
+/*
+ * Set up the filesystem mount context.
+ */
+static int efs_init_fs_context(struct fs_context *fc)
+{
+	struct efs_context *ctx;
+
+	ctx = kzalloc(sizeof(struct efs_context), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+	fc->fs_private = ctx;
+	fc->ops = &efs_context_opts;
+
+	return 0;
+}
+
 static int efs_statfs(struct dentry *dentry, struct kstatfs *buf) {
 	struct super_block *sb = dentry->d_sb;
 	struct efs_sb_info *sbi = SUPER_INFO(sb);