/* General filesystem local caching manager
   *
   * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
   * Written by David Howells (dhowells@redhat.com)
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; either version
   * 2 of the License, or (at your option) any later version.
   */
  
  #define FSCACHE_DEBUG_LEVEL CACHE
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/sched.h>
  #include <linux/completion.h>
  #include <linux/slab.h>
  #include <linux/seq_file.h>
  #include "internal.h"
  
  MODULE_DESCRIPTION("FS Cache Manager");
  MODULE_AUTHOR("Red Hat, Inc.");
  MODULE_LICENSE("GPL");
  
  unsigned fscache_defer_lookup = 1;
  module_param_named(defer_lookup, fscache_defer_lookup, uint,
  		   S_IWUSR | S_IRUGO);
  MODULE_PARM_DESC(fscache_defer_lookup,
  		 "Defer cookie lookup to background thread");
  
  unsigned fscache_defer_create = 1;
  module_param_named(defer_create, fscache_defer_create, uint,
  		   S_IWUSR | S_IRUGO);
  MODULE_PARM_DESC(fscache_defer_create,
  		 "Defer cookie creation to background thread");
  
  unsigned fscache_debug;
  module_param_named(debug, fscache_debug, uint,
  		   S_IWUSR | S_IRUGO);
  MODULE_PARM_DESC(fscache_debug,
  		 "FS-Cache debugging mask");
  
  struct kobject *fscache_root;
  struct workqueue_struct *fscache_object_wq;
  struct workqueue_struct *fscache_op_wq;
  
  DEFINE_PER_CPU(wait_queue_head_t, fscache_object_cong_wait);
  
  /* these values serve as lower bounds, will be adjusted in fscache_init() */
  static unsigned fscache_object_max_active = 4;
  static unsigned fscache_op_max_active = 2;
  
  #ifdef CONFIG_SYSCTL
  static struct ctl_table_header *fscache_sysctl_header;
  
  static int fscache_max_active_sysctl(struct ctl_table *table, int write,
  				     void __user *buffer,
  				     size_t *lenp, loff_t *ppos)
  {
  	struct workqueue_struct **wqp = table->extra1;
  	unsigned int *datap = table->data;
  	int ret;
  
  	ret = proc_dointvec(table, write, buffer, lenp, ppos);
  	if (ret == 0)
  		workqueue_set_max_active(*wqp, *datap);
  	return ret;
  }
  
  ctl_table fscache_sysctls[] = {
  	{
  		.procname	= "object_max_active",
  		.data		= &fscache_object_max_active,
  		.maxlen		= sizeof(unsigned),
  		.mode		= 0644,
  		.proc_handler	= fscache_max_active_sysctl,
  		.extra1		= &fscache_object_wq,
  	},
  	{
  		.procname	= "operation_max_active",
  		.data		= &fscache_op_max_active,
  		.maxlen		= sizeof(unsigned),
  		.mode		= 0644,
  		.proc_handler	= fscache_max_active_sysctl,
  		.extra1		= &fscache_op_wq,
  	},
  	{}
  };
  
  ctl_table fscache_sysctls_root[] = {
  	{
  		.procname	= "fscache",
  		.mode		= 0555,
  		.child		= fscache_sysctls,
  	},
  	{}
  };
  #endif
  
  /*
   * initialise the fs caching module
   */
  static int __init fscache_init(void)
  {
  	unsigned int nr_cpus = num_possible_cpus();
  	unsigned int cpu;
  	int ret;
  
  	fscache_object_max_active =
  		clamp_val(nr_cpus,
  			  fscache_object_max_active, WQ_UNBOUND_MAX_ACTIVE);
  
  	ret = -ENOMEM;
  	fscache_object_wq = alloc_workqueue("fscache_object", WQ_UNBOUND,
  					    fscache_object_max_active);
  	if (!fscache_object_wq)
  		goto error_object_wq;
  
  	fscache_op_max_active =
  		clamp_val(fscache_object_max_active / 2,
  			  fscache_op_max_active, WQ_UNBOUND_MAX_ACTIVE);
  
  	ret = -ENOMEM;
  	fscache_op_wq = alloc_workqueue("fscache_operation", WQ_UNBOUND,
  					fscache_op_max_active);
  	if (!fscache_op_wq)
  		goto error_op_wq;
  
  	for_each_possible_cpu(cpu)
  		init_waitqueue_head(&per_cpu(fscache_object_cong_wait, cpu));
  
  	ret = fscache_proc_init();
  	if (ret < 0)
  		goto error_proc;
  
  #ifdef CONFIG_SYSCTL
  	ret = -ENOMEM;
  	fscache_sysctl_header = register_sysctl_table(fscache_sysctls_root);
  	if (!fscache_sysctl_header)
  		goto error_sysctl;
  #endif
  
  	fscache_cookie_jar = kmem_cache_create("fscache_cookie_jar",
  					       sizeof(struct fscache_cookie),
  					       0,
  					       0,
  					       fscache_cookie_init_once);
  	if (!fscache_cookie_jar) {
  		printk(KERN_NOTICE
  		       "FS-Cache: Failed to allocate a cookie jar
  ");
  		ret = -ENOMEM;
  		goto error_cookie_jar;
  	}
  
  	fscache_root = kobject_create_and_add("fscache", kernel_kobj);
  	if (!fscache_root)
  		goto error_kobj;
  
  	printk(KERN_NOTICE "FS-Cache: Loaded
  ");
  	return 0;
  
  error_kobj:
  	kmem_cache_destroy(fscache_cookie_jar);
  error_cookie_jar:
  #ifdef CONFIG_SYSCTL
  	unregister_sysctl_table(fscache_sysctl_header);
  error_sysctl:
  #endif
  	fscache_proc_cleanup();
  error_proc:
  	destroy_workqueue(fscache_op_wq);
  error_op_wq:
  	destroy_workqueue(fscache_object_wq);
  error_object_wq:
  	return ret;
  }
  
  fs_initcall(fscache_init);
  
  /*
   * clean up on module removal
   */
  static void __exit fscache_exit(void)
  {
  	_enter("");
  
  	kobject_put(fscache_root);
  	kmem_cache_destroy(fscache_cookie_jar);
  #ifdef CONFIG_SYSCTL
  	unregister_sysctl_table(fscache_sysctl_header);
  #endif
  	fscache_proc_cleanup();
  	destroy_workqueue(fscache_op_wq);
  	destroy_workqueue(fscache_object_wq);
  	printk(KERN_NOTICE "FS-Cache: Unloaded
  ");
  }
  
  module_exit(fscache_exit);
  
  /*
   * wait_on_bit() sleep function for uninterruptible waiting
   */
  int fscache_wait_bit(void *flags)
  {
  	schedule();
  	return 0;
  }
  
  /*
   * wait_on_bit() sleep function for interruptible waiting
   */
  int fscache_wait_bit_interruptible(void *flags)
  {
  	schedule();
  	return signal_pending(current);
  }
  
  /*
   * wait_on_atomic_t() sleep function for uninterruptible waiting
   */
  int fscache_wait_atomic_t(atomic_t *p)
  {
  	schedule();
  	return 0;
  }