1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
2 * vim:expandtab:shiftwidth=8:tabstop=8:
6 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 only,
10 * as published by the Free Software Foundation.
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * General Public License version 2 for more details (a copy is included
16 * in the LICENSE file that accompanied this code).
18 * You should have received a copy of the GNU General Public License
19 * version 2 along with this program; If not, see
20 * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
22 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
23 * CA 95054 USA or visit www.sun.com if you need additional information or
29 * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
30 * Use is subject to license terms.
33 * This file is part of Lustre, http://www.lustre.org/
34 * Lustre is a trademark of Sun Microsystems, Inc.
36 * Implementation of cl_lock for LOVSUB layer.
38 * Author: Nikita Danilov <nikita.danilov@sun.com>
41 #define DEBUG_SUBSYSTEM S_LOV
43 #include "lov_cl_internal.h"
49 /*****************************************************************************
51 * Lovsub lock operations.
55 static void lovsub_lock_fini(const struct lu_env *env,
56 struct cl_lock_slice *slice)
58 struct lovsub_lock *lsl;
61 lsl = cl2lovsub_lock(slice);
62 LASSERT(list_empty(&lsl->lss_parents));
63 OBD_SLAB_FREE_PTR(lsl, lovsub_lock_kmem);
67 static void lovsub_parent_lock(const struct lu_env *env, struct lov_lock *lov)
69 struct cl_lock *parent;
72 parent = lov->lls_cl.cls_lock;
74 lu_ref_add(&parent->cll_reference, "lovsub-parent", cfs_current());
75 cl_lock_mutex_get(env, parent);
79 static void lovsub_parent_unlock(const struct lu_env *env, struct lov_lock *lov)
81 struct cl_lock *parent;
84 parent = lov->lls_cl.cls_lock;
85 cl_lock_mutex_put(env, lov->lls_cl.cls_lock);
86 lu_ref_del(&parent->cll_reference, "lovsub-parent", cfs_current());
87 cl_lock_put(env, parent);
91 static int lovsub_lock_state_one(const struct lu_env *env,
92 const struct lovsub_lock *lovsub,
95 struct cl_lock *parent;
96 struct cl_lock *child;
100 parent = lov->lls_cl.cls_lock;
101 child = lovsub->lss_cl.cls_lock;
103 if (lovsub->lss_active != parent) {
104 lovsub_parent_lock(env, lov);
105 if (child->cll_error != 0 && parent->cll_error == 0) {
107 * This is a deadlock case:
108 * cl_lock_error(for the parent lock)
111 * -> cl_lock_enclosure
112 * -> cl_lock_mutex_try(for the child lock)
114 cl_lock_mutex_put(env, child);
115 cl_lock_error(env, parent, child->cll_error);
118 cl_lock_signal(env, parent);
120 lovsub_parent_unlock(env, lov);
126 * Implements cl_lock_operations::clo_state() method for lovsub layer, which
127 * method is called whenever sub-lock state changes. Propagates state change
130 static void lovsub_lock_state(const struct lu_env *env,
131 const struct cl_lock_slice *slice,
132 enum cl_lock_state state)
134 struct lovsub_lock *sub = cl2lovsub_lock(slice);
135 struct lov_lock_link *scan;
138 LASSERT(cl_lock_is_mutexed(slice->cls_lock));
143 list_for_each_entry(scan, &sub->lss_parents, lll_list) {
144 restart = lovsub_lock_state_one(env, sub,
147 cl_lock_mutex_get(env, slice->cls_lock);
156 * Implementation of cl_lock_operation::clo_weigh() estimating lock weight by
157 * asking parent lock.
159 static unsigned long lovsub_lock_weigh(const struct lu_env *env,
160 const struct cl_lock_slice *slice)
162 struct lovsub_lock *lock = cl2lovsub_lock(slice);
163 struct lov_lock *lov;
164 unsigned long dumbbell;
168 LASSERT(cl_lock_is_mutexed(slice->cls_lock));
170 if (!list_empty(&lock->lss_parents)) {
172 * It is not clear whether all parents have to be asked and
173 * their estimations summed, or it is enough to ask one. For
174 * the current usages, one is always enough.
176 lov = container_of(lock->lss_parents.next,
177 struct lov_lock_link, lll_list)->lll_super;
179 lovsub_parent_lock(env, lov);
180 dumbbell = cl_lock_weigh(env, lov->lls_cl.cls_lock);
181 lovsub_parent_unlock(env, lov);
189 * Maps start/end offsets within a stripe, to offsets within a file.
191 static void lovsub_lock_descr_map(const struct cl_lock_descr *in,
192 struct lov_object *obj,
193 int stripe, struct cl_lock_descr *out)
195 struct lov_stripe_md *lsm = lov_r0(obj)->lo_lsm;
196 pgoff_t size; /* stripe size in pages */
197 pgoff_t skip; /* how many pages in every stripe are occupied by
203 start = in->cld_start;
207 * XXX join file support.
209 if (lsm->lsm_stripe_count > 1) {
210 size = cl_index(lov2cl(obj), lsm->lsm_stripe_size);
211 skip = (lsm->lsm_stripe_count - 1) * size;
213 /* XXX overflow check here? */
214 start += start/size * skip + stripe * size;
216 if (end != CL_PAGE_EOF) {
217 end += end/size * skip + stripe * size;
219 * And check for overflow...
221 if (end < in->cld_end)
225 out->cld_start = start;
231 * Adjusts parent lock extent when a sub-lock is attached to a parent. This is
232 * called in two ways:
234 * - as part of receive call-back, when server returns granted extent to
237 * - when top-lock finds existing sub-lock in the cache.
239 * Note, that lock mode is not propagated to the parent: i.e., if CLM_READ
240 * top-lock matches CLM_WRITE sub-lock, top-lock is still CLM_READ.
242 int lov_sublock_modify(const struct lu_env *env, struct lov_lock *lov,
243 struct lovsub_lock *sublock,
244 const struct cl_lock_descr *d, int idx)
246 struct cl_lock *parent;
247 struct cl_lock *child;
248 struct lovsub_object *subobj;
249 struct cl_lock_descr *pd;
250 struct cl_lock_descr *parent_descr;
253 parent = lov->lls_cl.cls_lock;
254 parent_descr = &parent->cll_descr;
255 LASSERT(cl_lock_mode_match(d->cld_mode, parent_descr->cld_mode));
257 child = sublock->lss_cl.cls_lock;
258 subobj = cl2lovsub(sublock->lss_cl.cls_obj);
259 pd = &lov_env_info(env)->lti_ldescr;
261 pd->cld_obj = parent_descr->cld_obj;
262 pd->cld_mode = parent_descr->cld_mode;
263 pd->cld_gid = parent_descr->cld_gid;
264 lovsub_lock_descr_map(d, subobj->lso_super, subobj->lso_index, pd);
265 lov->lls_sub[idx].sub_got = *d;
267 * Notify top-lock about modification, if lock description changes
270 if (!cl_lock_ext_match(parent_descr, pd))
271 result = cl_lock_modify(env, parent, pd);
277 static int lovsub_lock_modify(const struct lu_env *env,
278 const struct cl_lock_slice *s,
279 const struct cl_lock_descr *d)
281 struct lovsub_lock *lock = cl2lovsub_lock(s);
282 struct lov_lock_link *scan;
283 struct lov_lock *lov;
288 LASSERT(cl_lock_mode_match(d->cld_mode,
289 s->cls_lock->cll_descr.cld_mode));
290 list_for_each_entry(scan, &lock->lss_parents, lll_list) {
293 lov = scan->lll_super;
294 lovsub_parent_lock(env, lov);
295 rc = lov_sublock_modify(env, lov, lock, d, scan->lll_idx);
296 lovsub_parent_unlock(env, lov);
297 result = result ?: rc;
302 static int lovsub_lock_closure(const struct lu_env *env,
303 const struct cl_lock_slice *slice,
304 struct cl_lock_closure *closure)
306 struct lovsub_lock *sub;
307 struct cl_lock *parent;
308 struct lov_lock_link *scan;
311 LASSERT(cl_lock_is_mutexed(slice->cls_lock));
314 sub = cl2lovsub_lock(slice);
317 list_for_each_entry(scan, &sub->lss_parents, lll_list) {
318 parent = scan->lll_super->lls_cl.cls_lock;
319 result = cl_lock_closure_build(env, parent, closure);
327 * A helper function for lovsub_lock_delete() that deals with a given parent
330 static int lovsub_lock_delete_one(const struct lu_env *env,
331 struct cl_lock *child, struct lov_lock *lov)
333 struct cl_lock *parent;
337 parent = lov->lls_cl.cls_lock;
340 switch (parent->cll_state) {
345 cl_lock_signal(env, parent);
349 * Here lies a problem: a sub-lock is canceled while top-lock
350 * is being unlocked. Top-lock cannot be moved into CLS_NEW
351 * state, because unlocking has to succeed eventually by
352 * placing lock into CLS_CACHED (or failing it), see
353 * cl_unuse_try(). Nor can top-lock be left in CLS_CACHED
354 * state, because lov maintains an invariant that all
355 * sub-locks exist in CLS_CACHED (this allows cached top-lock
356 * to be reused immediately). Nor can we wait for top-lock
357 * state to change, because this can be synchronous to the
360 * We know for sure that lov_lock_unuse() will be called at
361 * least one more time to finish un-using, so leave a mark on
362 * the top-lock, that will be seen by the next call to
365 if (cl_lock_is_intransit(parent))
366 lov->lls_cancel_race = 1;
370 * if a sub-lock is canceled move its top-lock into CLS_NEW
371 * state to preserve an invariant that a top-lock in
372 * CLS_CACHED is immediately ready for re-use (i.e., has all
373 * sub-locks), and so that next attempt to re-use the top-lock
374 * enqueues missing sub-lock.
376 cl_lock_state_set(env, parent, CLS_NEW);
378 * if last sub-lock is canceled, destroy the top-lock (which
379 * is now `empty') proactively.
381 if (lov->lls_nr_filled == 0) {
382 /* ... but unfortunately, this cannot be done easily,
383 * as cancellation of a top-lock might acquire mutices
384 * of its other sub-locks, violating lock ordering,
385 * see cl_lock_{cancel,delete}() preconditions.
387 * To work around this, the mutex of this sub-lock is
388 * released, top-lock is destroyed, and sub-lock mutex
389 * acquired again. The list of parents has to be
390 * re-scanned from the beginning after this.
392 * Only do this if no mutices other than on @child and
393 * @parent are held by the current thread.
395 * TODO: The lock modal here is too complex, because
396 * the lock may be canceled and deleted by voluntarily:
398 * -> osc_lock_enqueue_wait
399 * -> osc_lock_cancel_wait
401 * -> lovsub_lock_delete
402 * -> cl_lock_cancel/delete
405 * The better choice is to spawn a kernel thread for
408 if (cl_lock_nr_mutexed(env) == 2) {
409 cl_lock_mutex_put(env, child);
410 cl_lock_cancel(env, parent);
411 cl_lock_delete(env, parent);
418 CERROR("Impossible state: %i\n", parent->cll_state);
426 * An implementation of cl_lock_operations::clo_delete() method. This is
427 * invoked in "bottom-to-top" delete, when lock destruction starts from the
428 * sub-lock (e.g, as a result of ldlm lock LRU policy).
430 static void lovsub_lock_delete(const struct lu_env *env,
431 const struct cl_lock_slice *slice)
433 struct cl_lock *child = slice->cls_lock;
434 struct lovsub_lock *sub = cl2lovsub_lock(slice);
437 LASSERT(cl_lock_is_mutexed(child));
441 * Destruction of a sub-lock might take multiple iterations, because
442 * when the last sub-lock of a given top-lock is deleted, top-lock is
443 * canceled proactively, and this requires to release sub-lock
444 * mutex. Once sub-lock mutex has been released, list of its parents
445 * has to be re-scanned from the beginning.
448 struct lov_lock *lov;
449 struct lov_lock_link *scan;
450 struct lov_lock_link *temp;
451 struct lov_lock_sub *subdata;
454 list_for_each_entry_safe(scan, temp,
455 &sub->lss_parents, lll_list) {
456 lov = scan->lll_super;
457 subdata = &lov->lls_sub[scan->lll_idx];
458 lovsub_parent_lock(env, lov);
459 subdata->sub_got = subdata->sub_descr;
460 lov_lock_unlink(env, scan, sub);
461 restart = lovsub_lock_delete_one(env, child, lov);
462 lovsub_parent_unlock(env, lov);
465 cl_lock_mutex_get(env, child);
473 static int lovsub_lock_print(const struct lu_env *env, void *cookie,
474 lu_printer_t p, const struct cl_lock_slice *slice)
476 struct lovsub_lock *sub = cl2lovsub_lock(slice);
477 struct lov_lock *lov;
478 struct lov_lock_link *scan;
480 list_for_each_entry(scan, &sub->lss_parents, lll_list) {
481 lov = scan->lll_super;
482 (*p)(env, cookie, "[%d %p ", scan->lll_idx, lov);
484 cl_lock_descr_print(env, cookie, p,
485 &lov->lls_cl.cls_lock->cll_descr);
486 (*p)(env, cookie, "] ");
491 static const struct cl_lock_operations lovsub_lock_ops = {
492 .clo_fini = lovsub_lock_fini,
493 .clo_state = lovsub_lock_state,
494 .clo_delete = lovsub_lock_delete,
495 .clo_modify = lovsub_lock_modify,
496 .clo_closure = lovsub_lock_closure,
497 .clo_weigh = lovsub_lock_weigh,
498 .clo_print = lovsub_lock_print
501 int lovsub_lock_init(const struct lu_env *env, struct cl_object *obj,
502 struct cl_lock *lock, const struct cl_io *io)
504 struct lovsub_lock *lsk;
508 OBD_SLAB_ALLOC_PTR_GFP(lsk, lovsub_lock_kmem, CFS_ALLOC_IO);
510 CFS_INIT_LIST_HEAD(&lsk->lss_parents);
511 cl_lock_slice_add(lock, &lsk->lss_cl, obj, &lovsub_lock_ops);