main.c
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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright 2018 Google LLC
*/
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/module.h>
#include <uapi/linux/incrementalfs.h>
#include "vfs.h"
#define INCFS_NODE_FEATURES "features"
static struct file_system_type incfs_fs_type = {
.owner = THIS_MODULE,
.name = INCFS_NAME,
.mount = incfs_mount_fs,
.kill_sb = incfs_kill_sb,
.fs_flags = 0
};
static struct kobject *sysfs_root, *featurefs_root;
static ssize_t supported(struct kobject *kobj,
struct kobj_attribute *attr, char *buff)
{
return snprintf(buff, PAGE_SIZE, "supported\n");
}
typedef ssize_t (*const attr_show)(struct kobject *kobj,
struct kobj_attribute *attr, char *buff);
#define _DECLARE_FEATURE_FLAG(name) \
static attr_show name##_show = supported; \
static struct kobj_attribute name##_attr = __ATTR_RO(name)
#define DECLARE_FEATURE_FLAG(name) _DECLARE_FEATURE_FLAG(name)
DECLARE_FEATURE_FLAG(corefs);
DECLARE_FEATURE_FLAG(zstd);
DECLARE_FEATURE_FLAG(v2);
static struct attribute *attributes[] = {
&corefs_attr.attr,
&zstd_attr.attr,
&v2_attr.attr,
NULL,
};
static const struct attribute_group attr_group = {
.attrs = attributes,
};
static int __init init_sysfs(void)
{
int res = 0;
sysfs_root = kobject_create_and_add(INCFS_NAME, fs_kobj);
if (!sysfs_root)
return -ENOMEM;
featurefs_root = kobject_create_and_add(INCFS_NODE_FEATURES,
sysfs_root);
if (!featurefs_root)
return -ENOMEM;
res = sysfs_create_group(featurefs_root, &attr_group);
if (res) {
kobject_put(sysfs_root);
sysfs_root = NULL;
}
return res;
}
static void cleanup_sysfs(void)
{
if (featurefs_root) {
sysfs_remove_group(featurefs_root, &attr_group);
kobject_put(featurefs_root);
featurefs_root = NULL;
}
if (sysfs_root) {
kobject_put(sysfs_root);
sysfs_root = NULL;
}
}
static int __init init_incfs_module(void)
{
int err = 0;
err = init_sysfs();
if (err)
return err;
err = register_filesystem(&incfs_fs_type);
if (err)
cleanup_sysfs();
return err;
}
static void __exit cleanup_incfs_module(void)
{
cleanup_sysfs();
unregister_filesystem(&incfs_fs_type);
}
module_init(init_incfs_module);
module_exit(cleanup_incfs_module);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Eugene Zemtsov <ezemtsov@google.com>");
MODULE_DESCRIPTION("Incremental File System");