// SPDX-License-Identifier: GPL-2.0-or-later
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/* General filesystem local caching manager
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*
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* Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#define FSCACHE_DEBUG_LEVEL CACHE
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/completion.h>
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#include <linux/slab.h>
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#include <linux/seq_file.h>
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#define CREATE_TRACE_POINTS
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#include "internal.h"
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MODULE_DESCRIPTION("FS Cache Manager");
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MODULE_AUTHOR("Red Hat, Inc.");
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MODULE_LICENSE("GPL");
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unsigned fscache_defer_lookup = 1;
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module_param_named(defer_lookup, fscache_defer_lookup, uint,
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S_IWUSR | S_IRUGO);
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MODULE_PARM_DESC(fscache_defer_lookup,
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"Defer cookie lookup to background thread");
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unsigned fscache_defer_create = 1;
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module_param_named(defer_create, fscache_defer_create, uint,
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S_IWUSR | S_IRUGO);
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MODULE_PARM_DESC(fscache_defer_create,
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"Defer cookie creation to background thread");
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unsigned fscache_debug;
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module_param_named(debug, fscache_debug, uint,
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S_IWUSR | S_IRUGO);
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MODULE_PARM_DESC(fscache_debug,
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"FS-Cache debugging mask");
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struct kobject *fscache_root;
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struct workqueue_struct *fscache_object_wq;
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struct workqueue_struct *fscache_op_wq;
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DEFINE_PER_CPU(wait_queue_head_t, fscache_object_cong_wait);
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/* these values serve as lower bounds, will be adjusted in fscache_init() */
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static unsigned fscache_object_max_active = 4;
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static unsigned fscache_op_max_active = 2;
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#ifdef CONFIG_SYSCTL
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static struct ctl_table_header *fscache_sysctl_header;
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static int fscache_max_active_sysctl(struct ctl_table *table, int write,
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void *buffer, size_t *lenp, loff_t *ppos)
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{
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struct workqueue_struct **wqp = table->extra1;
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unsigned int *datap = table->data;
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int ret;
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ret = proc_dointvec(table, write, buffer, lenp, ppos);
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if (ret == 0)
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workqueue_set_max_active(*wqp, *datap);
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return ret;
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}
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static struct ctl_table fscache_sysctls[] = {
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{
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.procname = "object_max_active",
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.data = &fscache_object_max_active,
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.maxlen = sizeof(unsigned),
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.mode = 0644,
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.proc_handler = fscache_max_active_sysctl,
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.extra1 = &fscache_object_wq,
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},
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{
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.procname = "operation_max_active",
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.data = &fscache_op_max_active,
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.maxlen = sizeof(unsigned),
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.mode = 0644,
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.proc_handler = fscache_max_active_sysctl,
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.extra1 = &fscache_op_wq,
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},
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{}
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};
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static struct ctl_table fscache_sysctls_root[] = {
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{
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.procname = "fscache",
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.mode = 0555,
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.child = fscache_sysctls,
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},
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{}
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};
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#endif
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/*
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* Mixing scores (in bits) for (7,20):
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* Input delta: 1-bit 2-bit
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* 1 round: 330.3 9201.6
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* 2 rounds: 1246.4 25475.4
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* 3 rounds: 1907.1 31295.1
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* 4 rounds: 2042.3 31718.6
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* Perfect: 2048 31744
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* (32*64) (32*31/2 * 64)
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*/
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#define HASH_MIX(x, y, a) \
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( x ^= (a), \
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y ^= x, x = rol32(x, 7),\
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x += y, y = rol32(y,20),\
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y *= 9 )
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static inline unsigned int fold_hash(unsigned long x, unsigned long y)
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{
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/* Use arch-optimized multiply if one exists */
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return __hash_32(y ^ __hash_32(x));
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}
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/*
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* Generate a hash. This is derived from full_name_hash(), but we want to be
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* sure it is arch independent and that it doesn't change as bits of the
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* computed hash value might appear on disk. The caller also guarantees that
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* the hashed data will be a series of aligned 32-bit words.
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*/
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unsigned int fscache_hash(unsigned int salt, unsigned int *data, unsigned int n)
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{
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unsigned int a, x = 0, y = salt;
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for (; n; n--) {
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a = *data++;
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HASH_MIX(x, y, a);
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}
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return fold_hash(x, y);
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}
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/*
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* initialise the fs caching module
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*/
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static int __init fscache_init(void)
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{
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unsigned int nr_cpus = num_possible_cpus();
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unsigned int cpu;
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int ret;
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fscache_object_max_active =
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clamp_val(nr_cpus,
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fscache_object_max_active, WQ_UNBOUND_MAX_ACTIVE);
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ret = -ENOMEM;
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fscache_object_wq = alloc_workqueue("fscache_object", WQ_UNBOUND,
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fscache_object_max_active);
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if (!fscache_object_wq)
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goto error_object_wq;
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fscache_op_max_active =
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clamp_val(fscache_object_max_active / 2,
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fscache_op_max_active, WQ_UNBOUND_MAX_ACTIVE);
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ret = -ENOMEM;
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fscache_op_wq = alloc_workqueue("fscache_operation", WQ_UNBOUND,
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fscache_op_max_active);
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if (!fscache_op_wq)
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goto error_op_wq;
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for_each_possible_cpu(cpu)
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init_waitqueue_head(&per_cpu(fscache_object_cong_wait, cpu));
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ret = fscache_proc_init();
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if (ret < 0)
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goto error_proc;
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#ifdef CONFIG_SYSCTL
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ret = -ENOMEM;
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fscache_sysctl_header = register_sysctl_table(fscache_sysctls_root);
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if (!fscache_sysctl_header)
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goto error_sysctl;
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#endif
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fscache_cookie_jar = kmem_cache_create("fscache_cookie_jar",
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sizeof(struct fscache_cookie),
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0, 0, NULL);
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if (!fscache_cookie_jar) {
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pr_notice("Failed to allocate a cookie jar\n");
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ret = -ENOMEM;
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goto error_cookie_jar;
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}
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fscache_root = kobject_create_and_add("fscache", kernel_kobj);
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if (!fscache_root)
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goto error_kobj;
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pr_notice("Loaded\n");
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return 0;
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error_kobj:
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kmem_cache_destroy(fscache_cookie_jar);
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error_cookie_jar:
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#ifdef CONFIG_SYSCTL
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unregister_sysctl_table(fscache_sysctl_header);
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error_sysctl:
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#endif
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fscache_proc_cleanup();
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error_proc:
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destroy_workqueue(fscache_op_wq);
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error_op_wq:
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destroy_workqueue(fscache_object_wq);
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error_object_wq:
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return ret;
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}
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fs_initcall(fscache_init);
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/*
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* clean up on module removal
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*/
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static void __exit fscache_exit(void)
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{
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_enter("");
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kobject_put(fscache_root);
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kmem_cache_destroy(fscache_cookie_jar);
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#ifdef CONFIG_SYSCTL
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unregister_sysctl_table(fscache_sysctl_header);
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#endif
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fscache_proc_cleanup();
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destroy_workqueue(fscache_op_wq);
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destroy_workqueue(fscache_object_wq);
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pr_notice("Unloaded\n");
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}
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module_exit(fscache_exit);
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