1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* General filesystem local caching manager 3 * 4 * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 */ 7 8 #define FSCACHE_DEBUG_LEVEL CACHE 9 #include <linux/module.h> 10 #include <linux/init.h> 11 #include <linux/sched.h> 12 #include <linux/completion.h> 13 #include <linux/slab.h> 14 #include <linux/seq_file.h> 15 #define CREATE_TRACE_POINTS 16 #include "internal.h" 17 18 MODULE_DESCRIPTION("FS Cache Manager"); 19 MODULE_AUTHOR("Red Hat, Inc."); 20 MODULE_LICENSE("GPL"); 21 22 unsigned fscache_defer_lookup = 1; 23 module_param_named(defer_lookup, fscache_defer_lookup, uint, 24 S_IWUSR | S_IRUGO); 25 MODULE_PARM_DESC(fscache_defer_lookup, 26 "Defer cookie lookup to background thread"); 27 28 unsigned fscache_defer_create = 1; 29 module_param_named(defer_create, fscache_defer_create, uint, 30 S_IWUSR | S_IRUGO); 31 MODULE_PARM_DESC(fscache_defer_create, 32 "Defer cookie creation to background thread"); 33 34 unsigned fscache_debug; 35 module_param_named(debug, fscache_debug, uint, 36 S_IWUSR | S_IRUGO); 37 MODULE_PARM_DESC(fscache_debug, 38 "FS-Cache debugging mask"); 39 40 struct kobject *fscache_root; 41 struct workqueue_struct *fscache_object_wq; 42 struct workqueue_struct *fscache_op_wq; 43 44 DEFINE_PER_CPU(wait_queue_head_t, fscache_object_cong_wait); 45 46 /* these values serve as lower bounds, will be adjusted in fscache_init() */ 47 static unsigned fscache_object_max_active = 4; 48 static unsigned fscache_op_max_active = 2; 49 50 #ifdef CONFIG_SYSCTL 51 static struct ctl_table_header *fscache_sysctl_header; 52 53 static int fscache_max_active_sysctl(struct ctl_table *table, int write, 54 void *buffer, size_t *lenp, loff_t *ppos) 55 { 56 struct workqueue_struct **wqp = table->extra1; 57 unsigned int *datap = table->data; 58 int ret; 59 60 ret = proc_dointvec(table, write, buffer, lenp, ppos); 61 if (ret == 0) 62 workqueue_set_max_active(*wqp, *datap); 63 return ret; 64 } 65 66 static struct ctl_table fscache_sysctls[] = { 67 { 68 .procname = "object_max_active", 69 .data = &fscache_object_max_active, 70 .maxlen = sizeof(unsigned), 71 .mode = 0644, 72 .proc_handler = fscache_max_active_sysctl, 73 .extra1 = &fscache_object_wq, 74 }, 75 { 76 .procname = "operation_max_active", 77 .data = &fscache_op_max_active, 78 .maxlen = sizeof(unsigned), 79 .mode = 0644, 80 .proc_handler = fscache_max_active_sysctl, 81 .extra1 = &fscache_op_wq, 82 }, 83 {} 84 }; 85 86 static struct ctl_table fscache_sysctls_root[] = { 87 { 88 .procname = "fscache", 89 .mode = 0555, 90 .child = fscache_sysctls, 91 }, 92 {} 93 }; 94 #endif 95 96 /* 97 * Mixing scores (in bits) for (7,20): 98 * Input delta: 1-bit 2-bit 99 * 1 round: 330.3 9201.6 100 * 2 rounds: 1246.4 25475.4 101 * 3 rounds: 1907.1 31295.1 102 * 4 rounds: 2042.3 31718.6 103 * Perfect: 2048 31744 104 * (32*64) (32*31/2 * 64) 105 */ 106 #define HASH_MIX(x, y, a) \ 107 ( x ^= (a), \ 108 y ^= x, x = rol32(x, 7),\ 109 x += y, y = rol32(y,20),\ 110 y *= 9 ) 111 112 static inline unsigned int fold_hash(unsigned long x, unsigned long y) 113 { 114 /* Use arch-optimized multiply if one exists */ 115 return __hash_32(y ^ __hash_32(x)); 116 } 117 118 /* 119 * Generate a hash. This is derived from full_name_hash(), but we want to be 120 * sure it is arch independent and that it doesn't change as bits of the 121 * computed hash value might appear on disk. The caller also guarantees that 122 * the hashed data will be a series of aligned 32-bit words. 123 */ 124 unsigned int fscache_hash(unsigned int salt, unsigned int *data, unsigned int n) 125 { 126 unsigned int a, x = 0, y = salt; 127 128 for (; n; n--) { 129 a = *data++; 130 HASH_MIX(x, y, a); 131 } 132 return fold_hash(x, y); 133 } 134 135 /* 136 * initialise the fs caching module 137 */ 138 static int __init fscache_init(void) 139 { 140 unsigned int nr_cpus = num_possible_cpus(); 141 unsigned int cpu; 142 int ret; 143 144 fscache_object_max_active = 145 clamp_val(nr_cpus, 146 fscache_object_max_active, WQ_UNBOUND_MAX_ACTIVE); 147 148 ret = -ENOMEM; 149 fscache_object_wq = alloc_workqueue("fscache_object", WQ_UNBOUND, 150 fscache_object_max_active); 151 if (!fscache_object_wq) 152 goto error_object_wq; 153 154 fscache_op_max_active = 155 clamp_val(fscache_object_max_active / 2, 156 fscache_op_max_active, WQ_UNBOUND_MAX_ACTIVE); 157 158 ret = -ENOMEM; 159 fscache_op_wq = alloc_workqueue("fscache_operation", WQ_UNBOUND, 160 fscache_op_max_active); 161 if (!fscache_op_wq) 162 goto error_op_wq; 163 164 for_each_possible_cpu(cpu) 165 init_waitqueue_head(&per_cpu(fscache_object_cong_wait, cpu)); 166 167 ret = fscache_proc_init(); 168 if (ret < 0) 169 goto error_proc; 170 171 #ifdef CONFIG_SYSCTL 172 ret = -ENOMEM; 173 fscache_sysctl_header = register_sysctl_table(fscache_sysctls_root); 174 if (!fscache_sysctl_header) 175 goto error_sysctl; 176 #endif 177 178 fscache_cookie_jar = kmem_cache_create("fscache_cookie_jar", 179 sizeof(struct fscache_cookie), 180 0, 0, NULL); 181 if (!fscache_cookie_jar) { 182 pr_notice("Failed to allocate a cookie jar\n"); 183 ret = -ENOMEM; 184 goto error_cookie_jar; 185 } 186 187 fscache_root = kobject_create_and_add("fscache", kernel_kobj); 188 if (!fscache_root) 189 goto error_kobj; 190 191 pr_notice("Loaded\n"); 192 return 0; 193 194 error_kobj: 195 kmem_cache_destroy(fscache_cookie_jar); 196 error_cookie_jar: 197 #ifdef CONFIG_SYSCTL 198 unregister_sysctl_table(fscache_sysctl_header); 199 error_sysctl: 200 #endif 201 fscache_proc_cleanup(); 202 error_proc: 203 destroy_workqueue(fscache_op_wq); 204 error_op_wq: 205 destroy_workqueue(fscache_object_wq); 206 error_object_wq: 207 return ret; 208 } 209 210 fs_initcall(fscache_init); 211 212 /* 213 * clean up on module removal 214 */ 215 static void __exit fscache_exit(void) 216 { 217 _enter(""); 218 219 kobject_put(fscache_root); 220 kmem_cache_destroy(fscache_cookie_jar); 221 #ifdef CONFIG_SYSCTL 222 unregister_sysctl_table(fscache_sysctl_header); 223 #endif 224 fscache_proc_cleanup(); 225 destroy_workqueue(fscache_op_wq); 226 destroy_workqueue(fscache_object_wq); 227 pr_notice("Unloaded\n"); 228 } 229 230 module_exit(fscache_exit); 231