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27 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
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33 * This file is part of Lustre, http://www.lustre.org/
34 * Lustre is a trademark of Sun Microsystems, Inc.
36 * lustre/obdclass/lu_ref.c
40 * Author: Nikita Danilov <nikita.danilov@sun.com>
43 #define DEBUG_SUBSYSTEM S_CLASS
45 #include <libcfs/libcfs.h>
47 #include <obd_class.h>
48 #include <obd_support.h>
54 * Asserts a condition for a given lu_ref. Must be called with
55 * lu_ref::lf_guard held.
57 #define REFASSERT(ref, expr) do { \
58 struct lu_ref *__tmp = (ref); \
60 if (unlikely(!(expr))) { \
61 lu_ref_print(__tmp); \
62 spin_unlock(&__tmp->lf_guard); \
65 spin_lock(&__tmp->lf_guard); \
69 static struct kmem_cache *lu_ref_link_kmem;
71 static struct lu_kmem_descr lu_ref_caches[] = {
73 .ckd_cache = &lu_ref_link_kmem,
74 .ckd_name = "lu_ref_link_kmem",
75 .ckd_size = sizeof (struct lu_ref_link)
83 * Global list of active (initialized, but not finalized) lu_ref's.
85 * Protected by lu_ref_refs_guard.
87 static struct list_head lu_ref_refs;
88 static spinlock_t lu_ref_refs_guard;
89 static struct lu_ref lu_ref_marker = {
90 .lf_guard = __SPIN_LOCK_UNLOCKED(lu_ref_marker.lf_guard),
91 .lf_list = LIST_HEAD_INIT(lu_ref_marker.lf_list),
92 .lf_linkage = LIST_HEAD_INIT(lu_ref_marker.lf_linkage)
95 void lu_ref_print(const struct lu_ref *ref)
97 struct lu_ref_link *link;
99 CERROR("lu_ref: %p %d %d %s:%d\n",
100 ref, ref->lf_refs, ref->lf_failed, ref->lf_func, ref->lf_line);
101 list_for_each_entry(link, &ref->lf_list, ll_linkage) {
102 CERROR(" link: %s %p\n", link->ll_scope, link->ll_source);
105 EXPORT_SYMBOL(lu_ref_print);
107 static int lu_ref_is_marker(const struct lu_ref *ref)
109 return (ref == &lu_ref_marker);
112 void lu_ref_print_all(void)
116 spin_lock(&lu_ref_refs_guard);
117 list_for_each_entry(ref, &lu_ref_refs, lf_linkage) {
118 if (lu_ref_is_marker(ref))
121 spin_lock(&ref->lf_guard);
123 spin_unlock(&ref->lf_guard);
125 spin_unlock(&lu_ref_refs_guard);
127 EXPORT_SYMBOL(lu_ref_print_all);
129 void lu_ref_init_loc(struct lu_ref *ref, const char *func, const int line)
134 spin_lock_init(&ref->lf_guard);
135 INIT_LIST_HEAD(&ref->lf_list);
136 spin_lock(&lu_ref_refs_guard);
137 list_add(&ref->lf_linkage, &lu_ref_refs);
138 spin_unlock(&lu_ref_refs_guard);
140 EXPORT_SYMBOL(lu_ref_init_loc);
142 void lu_ref_fini(struct lu_ref *ref)
144 REFASSERT(ref, list_empty(&ref->lf_list));
145 REFASSERT(ref, ref->lf_refs == 0);
146 spin_lock(&lu_ref_refs_guard);
147 list_del_init(&ref->lf_linkage);
148 spin_unlock(&lu_ref_refs_guard);
150 EXPORT_SYMBOL(lu_ref_fini);
152 static struct lu_ref_link *lu_ref_add_context(struct lu_ref *ref,
157 struct lu_ref_link *link;
160 if (lu_ref_link_kmem != NULL) {
161 OBD_SLAB_ALLOC_PTR_GFP(link, lu_ref_link_kmem, flags);
164 link->ll_scope = scope;
165 link->ll_source = source;
166 spin_lock(&ref->lf_guard);
167 list_add_tail(&link->ll_linkage, &ref->lf_list);
169 spin_unlock(&ref->lf_guard);
174 spin_lock(&ref->lf_guard);
176 spin_unlock(&ref->lf_guard);
177 link = ERR_PTR(-ENOMEM);
183 void lu_ref_add(struct lu_ref *ref, const char *scope, const void *source)
186 lu_ref_add_context(ref, GFP_IOFS, scope, source);
188 EXPORT_SYMBOL(lu_ref_add);
190 void lu_ref_add_at(struct lu_ref *ref, struct lu_ref_link *link,
191 const char *scope, const void *source)
194 link->ll_scope = scope;
195 link->ll_source = source;
196 spin_lock(&ref->lf_guard);
197 list_add_tail(&link->ll_linkage, &ref->lf_list);
199 spin_unlock(&ref->lf_guard);
201 EXPORT_SYMBOL(lu_ref_add_at);
204 * Version of lu_ref_add() to be used in non-blockable contexts.
206 void lu_ref_add_atomic(struct lu_ref *ref, const char *scope,
209 lu_ref_add_context(ref, GFP_ATOMIC, scope, source);
211 EXPORT_SYMBOL(lu_ref_add_atomic);
213 static inline int lu_ref_link_eq(const struct lu_ref_link *link,
214 const char *scope, const void *source)
216 return link->ll_source == source && !strcmp(link->ll_scope, scope);
220 * Maximal chain length seen so far.
222 static unsigned lu_ref_chain_max_length = 127;
225 * Searches for a lu_ref_link with given [scope, source] within given lu_ref.
227 static struct lu_ref_link *lu_ref_find(struct lu_ref *ref, const char *scope,
230 struct lu_ref_link *link;
234 list_for_each_entry(link, &ref->lf_list, ll_linkage) {
236 if (lu_ref_link_eq(link, scope, source)) {
237 if (iterations > lu_ref_chain_max_length) {
238 CWARN("Long lu_ref chain %d \"%s\":%p\n",
239 iterations, scope, source);
240 lu_ref_chain_max_length = iterations * 3 / 2;
248 void lu_ref_del(struct lu_ref *ref, const char *scope, const void *source)
250 struct lu_ref_link *link;
252 spin_lock(&ref->lf_guard);
253 link = lu_ref_find(ref, scope, source);
255 list_del(&link->ll_linkage);
257 spin_unlock(&ref->lf_guard);
258 OBD_SLAB_FREE(link, lu_ref_link_kmem, sizeof(*link));
260 REFASSERT(ref, ref->lf_failed > 0);
262 spin_unlock(&ref->lf_guard);
265 EXPORT_SYMBOL(lu_ref_del);
267 void lu_ref_set_at(struct lu_ref *ref, struct lu_ref_link *link,
269 const void *source0, const void *source1)
271 REFASSERT(ref, link != NULL && !IS_ERR(link));
273 spin_lock(&ref->lf_guard);
274 REFASSERT(ref, link->ll_ref == ref);
275 REFASSERT(ref, lu_ref_link_eq(link, scope, source0));
276 link->ll_source = source1;
277 spin_unlock(&ref->lf_guard);
279 EXPORT_SYMBOL(lu_ref_set_at);
281 void lu_ref_del_at(struct lu_ref *ref, struct lu_ref_link *link,
282 const char *scope, const void *source)
284 REFASSERT(ref, link != NULL && !IS_ERR(link));
285 spin_lock(&ref->lf_guard);
286 REFASSERT(ref, link->ll_ref == ref);
287 REFASSERT(ref, lu_ref_link_eq(link, scope, source));
288 list_del(&link->ll_linkage);
290 spin_unlock(&ref->lf_guard);
292 EXPORT_SYMBOL(lu_ref_del_at);
294 #ifdef CONFIG_PROC_FS
296 static void *lu_ref_seq_start(struct seq_file *seq, loff_t *pos)
298 struct lu_ref *ref = seq->private;
300 spin_lock(&lu_ref_refs_guard);
301 if (list_empty(&ref->lf_linkage))
303 spin_unlock(&lu_ref_refs_guard);
308 static void *lu_ref_seq_next(struct seq_file *seq, void *p, loff_t *pos)
310 struct lu_ref *ref = p;
313 LASSERT(seq->private == p);
314 LASSERT(!list_empty(&ref->lf_linkage));
316 spin_lock(&lu_ref_refs_guard);
317 next = list_entry(ref->lf_linkage.next, struct lu_ref, lf_linkage);
318 if (&next->lf_linkage == &lu_ref_refs) {
322 list_move(&ref->lf_linkage, &next->lf_linkage);
324 spin_unlock(&lu_ref_refs_guard);
328 static void lu_ref_seq_stop(struct seq_file *seq, void *p)
334 static int lu_ref_seq_show(struct seq_file *seq, void *p)
336 struct lu_ref *ref = p;
339 spin_lock(&lu_ref_refs_guard);
340 next = list_entry(ref->lf_linkage.next, struct lu_ref, lf_linkage);
341 if ((&next->lf_linkage == &lu_ref_refs) || lu_ref_is_marker(next)) {
342 spin_unlock(&lu_ref_refs_guard);
346 /* print the entry */
347 spin_lock(&next->lf_guard);
348 seq_printf(seq, "lu_ref: %p %d %d %s:%d\n",
349 next, next->lf_refs, next->lf_failed,
350 next->lf_func, next->lf_line);
351 if (next->lf_refs > 64) {
352 seq_printf(seq, " too many references, skip\n");
354 struct lu_ref_link *link;
357 list_for_each_entry(link, &next->lf_list, ll_linkage)
358 seq_printf(seq, " #%d link: %s %p\n",
359 i++, link->ll_scope, link->ll_source);
361 spin_unlock(&next->lf_guard);
362 spin_unlock(&lu_ref_refs_guard);
367 static struct seq_operations lu_ref_seq_ops = {
368 .start = lu_ref_seq_start,
369 .stop = lu_ref_seq_stop,
370 .next = lu_ref_seq_next,
371 .show = lu_ref_seq_show
374 static int lu_ref_seq_open(struct inode *inode, struct file *file)
376 struct lu_ref *marker = &lu_ref_marker;
379 result = seq_open(file, &lu_ref_seq_ops);
381 spin_lock(&lu_ref_refs_guard);
382 if (!list_empty(&marker->lf_linkage))
385 list_add(&marker->lf_linkage, &lu_ref_refs);
386 spin_unlock(&lu_ref_refs_guard);
389 struct seq_file *f = file->private_data;
392 seq_release(inode, file);
399 static int lu_ref_seq_release(struct inode *inode, struct file *file)
401 struct lu_ref *ref = ((struct seq_file *)file->private_data)->private;
403 spin_lock(&lu_ref_refs_guard);
404 list_del_init(&ref->lf_linkage);
405 spin_unlock(&lu_ref_refs_guard);
407 return seq_release(inode, file);
410 static struct file_operations lu_ref_dump_fops = {
411 .owner = THIS_MODULE,
412 .open = lu_ref_seq_open,
415 .release = lu_ref_seq_release
418 #endif /* CONFIG_PROC_FS */
420 int lu_ref_global_init(void)
425 "lu_ref tracking is enabled. Performance isn't.\n");
427 INIT_LIST_HEAD(&lu_ref_refs);
428 spin_lock_init(&lu_ref_refs_guard);
429 result = lu_kmem_init(lu_ref_caches);
431 #ifdef CONFIG_PROC_FS
433 result = lprocfs_seq_create(proc_lustre_root, "lu_refs",
434 0444, &lu_ref_dump_fops, NULL);
436 lu_kmem_fini(lu_ref_caches);
438 #endif /* CONFIG_PROC_FS */
443 void lu_ref_global_fini(void)
445 #ifdef CONFIG_PROC_FS
446 lprocfs_remove_proc_entry("lu_refs", proc_lustre_root);
447 #endif /* CONFIG_PROC_FS */
448 lu_kmem_fini(lu_ref_caches);
451 #endif /* USE_LU_REF */