fs/cachefiles/main.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /* Network filesystem caching backend to use cache files on a premounted
0003  * filesystem
0004  *
0005  * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
0006  * Written by David Howells (dhowells@redhat.com)
0007  */
0008
0009 #include <linux/module.h>
0010 #include <linux/init.h>
0011 #include <linux/sched.h>
0012 #include <linux/completion.h>
0013 #include <linux/slab.h>
0014 #include <linux/fs.h>
0015 #include <linux/file.h>
0016 #include <linux/namei.h>
0017 #include <linux/mount.h>
0018 #include <linux/statfs.h>
0019 #include <linux/sysctl.h>
0020 #include <linux/miscdevice.h>
0021 #include <linux/netfs.h>
0022 #include <trace/events/netfs.h>
0023 #define CREATE_TRACE_POINTS
0024 #include "internal.h"
0025
0026 unsigned cachefiles_debug;
0027 module_param_named(debug, cachefiles_debug, uint, S_IWUSR | S_IRUGO);
0028 MODULE_PARM_DESC(cachefiles_debug, "CacheFiles debugging mask");
0029
0030 MODULE_DESCRIPTION("Mounted-filesystem based cache");
0031 MODULE_AUTHOR("Red Hat, Inc.");
0032 MODULE_LICENSE("GPL");
0033
0034 struct kmem_cache *cachefiles_object_jar;
0035
0036 static struct miscdevice cachefiles_dev = {
0037     .minor  = MISC_DYNAMIC_MINOR,
0038     .name   = "cachefiles",
0039     .fops   = &cachefiles_daemon_fops,
0040 };
0041
0042 /*
0043  * initialise the fs caching module
0044  */
0045 static int __init cachefiles_init(void)
0046 {
0047     int ret;
0048
0049     ret = cachefiles_register_error_injection();
0050     if (ret < 0)
0051         goto error_einj;
0052     ret = misc_register(&cachefiles_dev);
0053     if (ret < 0)
0054         goto error_dev;
0055
0056     /* create an object jar */
0057     ret = -ENOMEM;
0058     cachefiles_object_jar =
0059         kmem_cache_create("cachefiles_object_jar",
0060                   sizeof(struct cachefiles_object),
0061                   0, SLAB_HWCACHE_ALIGN, NULL);
0062     if (!cachefiles_object_jar) {
0063         pr_notice("Failed to allocate an object jar\n");
0064         goto error_object_jar;
0065     }
0066
0067     pr_info("Loaded\n");
0068     return 0;
0069
0070 error_object_jar:
0071     misc_deregister(&cachefiles_dev);
0072 error_dev:
0073     cachefiles_unregister_error_injection();
0074 error_einj:
0075     pr_err("failed to register: %d\n", ret);
0076     return ret;
0077 }
0078
0079 fs_initcall(cachefiles_init);
0080
0081 /*
0082  * clean up on module removal
0083  */
0084 static void __exit cachefiles_exit(void)
0085 {
0086     pr_info("Unloading\n");
0087
0088     kmem_cache_destroy(cachefiles_object_jar);
0089     misc_deregister(&cachefiles_dev);
0090     cachefiles_unregister_error_injection();
0091 }
0092
0093 module_exit(cachefiles_exit);