1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
2 * vim:expandtab:shiftwidth=8:tabstop=8:
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29 * Copyright 2008 Sun Microsystems, Inc. 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 * 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;
206 if (lsm->lsm_stripe_count > 1) {
207 size = cl_index(lov2cl(obj), lsm->lsm_stripe_size);
208 skip = (lsm->lsm_stripe_count - 1) * size;
210 /* XXX overflow check here? */
211 start += start/size * skip + stripe * size;
213 if (end != CL_PAGE_EOF) {
214 end += end/size * skip + stripe * size;
216 * And check for overflow...
218 if (end < in->cld_end)
222 out->cld_start = start;
228 * Adjusts parent lock extent when a sub-lock is attached to a parent. This is
229 * called in two ways:
231 * - as part of receive call-back, when server returns granted extent to
234 * - when top-lock finds existing sub-lock in the cache.
236 * Note, that lock mode is not propagated to the parent: i.e., if CLM_READ
237 * top-lock matches CLM_WRITE sub-lock, top-lock is still CLM_READ.
239 int lov_sublock_modify(const struct lu_env *env, struct lov_lock *lov,
240 struct lovsub_lock *sublock,
241 const struct cl_lock_descr *d, int idx)
243 struct cl_lock *parent;
244 struct cl_lock *child;
245 struct lovsub_object *subobj;
246 struct cl_lock_descr *pd;
247 struct cl_lock_descr *parent_descr;
250 parent = lov->lls_cl.cls_lock;
251 parent_descr = &parent->cll_descr;
252 LASSERT(cl_lock_mode_match(d->cld_mode, parent_descr->cld_mode));
254 child = sublock->lss_cl.cls_lock;
255 subobj = cl2lovsub(sublock->lss_cl.cls_obj);
256 pd = &lov_env_info(env)->lti_ldescr;
258 pd->cld_obj = parent_descr->cld_obj;
259 pd->cld_mode = parent_descr->cld_mode;
260 pd->cld_gid = parent_descr->cld_gid;
261 lovsub_lock_descr_map(d, subobj->lso_super, subobj->lso_index, pd);
262 lov->lls_sub[idx].sub_got = *d;
264 * Notify top-lock about modification, if lock description changes
267 if (!cl_lock_ext_match(parent_descr, pd))
268 result = cl_lock_modify(env, parent, pd);
274 static int lovsub_lock_modify(const struct lu_env *env,
275 const struct cl_lock_slice *s,
276 const struct cl_lock_descr *d)
278 struct lovsub_lock *lock = cl2lovsub_lock(s);
279 struct lov_lock_link *scan;
280 struct lov_lock *lov;
285 LASSERT(cl_lock_mode_match(d->cld_mode,
286 s->cls_lock->cll_descr.cld_mode));
287 list_for_each_entry(scan, &lock->lss_parents, lll_list) {
290 lov = scan->lll_super;
291 lovsub_parent_lock(env, lov);
292 rc = lov_sublock_modify(env, lov, lock, d, scan->lll_idx);
293 lovsub_parent_unlock(env, lov);
294 result = result ?: rc;
299 static int lovsub_lock_closure(const struct lu_env *env,
300 const struct cl_lock_slice *slice,
301 struct cl_lock_closure *closure)
303 struct lovsub_lock *sub;
304 struct cl_lock *parent;
305 struct lov_lock_link *scan;
308 LASSERT(cl_lock_is_mutexed(slice->cls_lock));
311 sub = cl2lovsub_lock(slice);
314 list_for_each_entry(scan, &sub->lss_parents, lll_list) {
315 parent = scan->lll_super->lls_cl.cls_lock;
316 result = cl_lock_closure_build(env, parent, closure);
324 * A helper function for lovsub_lock_delete() that deals with a given parent
327 static int lovsub_lock_delete_one(const struct lu_env *env,
328 struct cl_lock *child, struct lov_lock *lov)
330 struct cl_lock *parent;
334 parent = lov->lls_cl.cls_lock;
337 switch (parent->cll_state) {
342 cl_lock_signal(env, parent);
346 * Here lies a problem: a sub-lock is canceled while top-lock
347 * is being unlocked. Top-lock cannot be moved into CLS_NEW
348 * state, because unlocking has to succeed eventually by
349 * placing lock into CLS_CACHED (or failing it), see
350 * cl_unuse_try(). Nor can top-lock be left in CLS_CACHED
351 * state, because lov maintains an invariant that all
352 * sub-locks exist in CLS_CACHED (this allows cached top-lock
353 * to be reused immediately). Nor can we wait for top-lock
354 * state to change, because this can be synchronous to the
357 * We know for sure that lov_lock_unuse() will be called at
358 * least one more time to finish un-using, so leave a mark on
359 * the top-lock, that will be seen by the next call to
362 if (cl_lock_is_intransit(parent))
363 lov->lls_cancel_race = 1;
367 * if a sub-lock is canceled move its top-lock into CLS_NEW
368 * state to preserve an invariant that a top-lock in
369 * CLS_CACHED is immediately ready for re-use (i.e., has all
370 * sub-locks), and so that next attempt to re-use the top-lock
371 * enqueues missing sub-lock.
373 cl_lock_state_set(env, parent, CLS_NEW);
375 * if last sub-lock is canceled, destroy the top-lock (which
376 * is now `empty') proactively.
378 if (lov->lls_nr_filled == 0) {
379 /* ... but unfortunately, this cannot be done easily,
380 * as cancellation of a top-lock might acquire mutices
381 * of its other sub-locks, violating lock ordering,
382 * see cl_lock_{cancel,delete}() preconditions.
384 * To work around this, the mutex of this sub-lock is
385 * released, top-lock is destroyed, and sub-lock mutex
386 * acquired again. The list of parents has to be
387 * re-scanned from the beginning after this.
389 * Only do this if no mutices other than on @child and
390 * @parent are held by the current thread.
392 * TODO: The lock modal here is too complex, because
393 * the lock may be canceled and deleted by voluntarily:
395 * -> osc_lock_enqueue_wait
396 * -> osc_lock_cancel_wait
398 * -> lovsub_lock_delete
399 * -> cl_lock_cancel/delete
402 * The better choice is to spawn a kernel thread for
405 if (cl_lock_nr_mutexed(env) == 2) {
406 cl_lock_mutex_put(env, child);
407 cl_lock_cancel(env, parent);
408 cl_lock_delete(env, parent);
414 CL_LOCK_DEBUG(D_ERROR, env, parent, "Delete CLS_HELD lock\n");
416 CERROR("Impossible state: %i\n", parent->cll_state);
425 * An implementation of cl_lock_operations::clo_delete() method. This is
426 * invoked in "bottom-to-top" delete, when lock destruction starts from the
427 * sub-lock (e.g, as a result of ldlm lock LRU policy).
429 static void lovsub_lock_delete(const struct lu_env *env,
430 const struct cl_lock_slice *slice)
432 struct cl_lock *child = slice->cls_lock;
433 struct lovsub_lock *sub = cl2lovsub_lock(slice);
436 LASSERT(cl_lock_is_mutexed(child));
440 * Destruction of a sub-lock might take multiple iterations, because
441 * when the last sub-lock of a given top-lock is deleted, top-lock is
442 * canceled proactively, and this requires to release sub-lock
443 * mutex. Once sub-lock mutex has been released, list of its parents
444 * has to be re-scanned from the beginning.
447 struct lov_lock *lov;
448 struct lov_lock_link *scan;
449 struct lov_lock_link *temp;
450 struct lov_lock_sub *subdata;
453 list_for_each_entry_safe(scan, temp,
454 &sub->lss_parents, lll_list) {
455 lov = scan->lll_super;
456 subdata = &lov->lls_sub[scan->lll_idx];
457 lovsub_parent_lock(env, lov);
458 subdata->sub_got = subdata->sub_descr;
459 lov_lock_unlink(env, scan, sub);
460 restart = lovsub_lock_delete_one(env, child, lov);
461 lovsub_parent_unlock(env, lov);
464 cl_lock_mutex_get(env, child);
472 static int lovsub_lock_print(const struct lu_env *env, void *cookie,
473 lu_printer_t p, const struct cl_lock_slice *slice)
475 struct lovsub_lock *sub = cl2lovsub_lock(slice);
476 struct lov_lock *lov;
477 struct lov_lock_link *scan;
479 list_for_each_entry(scan, &sub->lss_parents, lll_list) {
480 lov = scan->lll_super;
481 (*p)(env, cookie, "[%d %p ", scan->lll_idx, lov);
483 cl_lock_descr_print(env, cookie, p,
484 &lov->lls_cl.cls_lock->cll_descr);
485 (*p)(env, cookie, "] ");
490 static const struct cl_lock_operations lovsub_lock_ops = {
491 .clo_fini = lovsub_lock_fini,
492 .clo_state = lovsub_lock_state,
493 .clo_delete = lovsub_lock_delete,
494 .clo_modify = lovsub_lock_modify,
495 .clo_closure = lovsub_lock_closure,
496 .clo_weigh = lovsub_lock_weigh,
497 .clo_print = lovsub_lock_print
500 int lovsub_lock_init(const struct lu_env *env, struct cl_object *obj,
501 struct cl_lock *lock, const struct cl_io *io)
503 struct lovsub_lock *lsk;
507 OBD_SLAB_ALLOC_PTR_GFP(lsk, lovsub_lock_kmem, CFS_ALLOC_IO);
509 CFS_INIT_LIST_HEAD(&lsk->lss_parents);
510 cl_lock_slice_add(lock, &lsk->lss_cl, obj, &lovsub_lock_ops);