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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(cfs_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);
92 * Implements cl_lock_operations::clo_state() method for lovsub layer, which
93 * method is called whenever sub-lock state changes. Propagates state change
96 static void lovsub_lock_state(const struct lu_env *env,
97 const struct cl_lock_slice *slice,
98 enum cl_lock_state state)
100 struct lovsub_lock *sub = cl2lovsub_lock(slice);
101 struct lov_lock_link *scan;
103 LASSERT(cl_lock_is_mutexed(slice->cls_lock));
106 cfs_list_for_each_entry(scan, &sub->lss_parents, lll_list) {
107 struct lov_lock *lov = scan->lll_super;
108 struct cl_lock *parent = lov->lls_cl.cls_lock;
110 if (sub->lss_active != parent) {
111 lovsub_parent_lock(env, lov);
112 cl_lock_signal(env, parent);
113 lovsub_parent_unlock(env, lov);
120 * Implementation of cl_lock_operation::clo_weigh() estimating lock weight by
121 * asking parent lock.
123 static unsigned long lovsub_lock_weigh(const struct lu_env *env,
124 const struct cl_lock_slice *slice)
126 struct lovsub_lock *lock = cl2lovsub_lock(slice);
127 struct lov_lock *lov;
128 unsigned long dumbbell;
132 LASSERT(cl_lock_is_mutexed(slice->cls_lock));
134 if (!cfs_list_empty(&lock->lss_parents)) {
136 * It is not clear whether all parents have to be asked and
137 * their estimations summed, or it is enough to ask one. For
138 * the current usages, one is always enough.
140 lov = container_of(lock->lss_parents.next,
141 struct lov_lock_link, lll_list)->lll_super;
143 lovsub_parent_lock(env, lov);
144 dumbbell = cl_lock_weigh(env, lov->lls_cl.cls_lock);
145 lovsub_parent_unlock(env, lov);
153 * Maps start/end offsets within a stripe, to offsets within a file.
155 static void lovsub_lock_descr_map(const struct cl_lock_descr *in,
156 struct lov_object *lov,
157 int stripe, struct cl_lock_descr *out)
159 pgoff_t size; /* stripe size in pages */
160 pgoff_t skip; /* how many pages in every stripe are occupied by
166 start = in->cld_start;
169 if (lov->lo_lsm->lsm_stripe_count > 1) {
170 size = cl_index(lov2cl(lov), lov->lo_lsm->lsm_stripe_size);
171 skip = (lov->lo_lsm->lsm_stripe_count - 1) * size;
173 /* XXX overflow check here? */
174 start += start/size * skip + stripe * size;
176 if (end != CL_PAGE_EOF) {
177 end += end/size * skip + stripe * size;
179 * And check for overflow...
181 if (end < in->cld_end)
185 out->cld_start = start;
191 * Adjusts parent lock extent when a sub-lock is attached to a parent. This is
192 * called in two ways:
194 * - as part of receive call-back, when server returns granted extent to
197 * - when top-lock finds existing sub-lock in the cache.
199 * Note, that lock mode is not propagated to the parent: i.e., if CLM_READ
200 * top-lock matches CLM_WRITE sub-lock, top-lock is still CLM_READ.
202 int lov_sublock_modify(const struct lu_env *env, struct lov_lock *lov,
203 struct lovsub_lock *sublock,
204 const struct cl_lock_descr *d, int idx)
206 struct cl_lock *parent;
207 struct lovsub_object *subobj;
208 struct cl_lock_descr *pd;
209 struct cl_lock_descr *parent_descr;
212 parent = lov->lls_cl.cls_lock;
213 parent_descr = &parent->cll_descr;
214 LASSERT(cl_lock_mode_match(d->cld_mode, parent_descr->cld_mode));
216 subobj = cl2lovsub(sublock->lss_cl.cls_obj);
217 pd = &lov_env_info(env)->lti_ldescr;
219 pd->cld_obj = parent_descr->cld_obj;
220 pd->cld_mode = parent_descr->cld_mode;
221 pd->cld_gid = parent_descr->cld_gid;
222 lovsub_lock_descr_map(d, subobj->lso_super, subobj->lso_index, pd);
223 lov->lls_sub[idx].sub_got = *d;
225 * Notify top-lock about modification, if lock description changes
228 if (!cl_lock_ext_match(parent_descr, pd))
229 result = cl_lock_modify(env, parent, pd);
235 static int lovsub_lock_modify(const struct lu_env *env,
236 const struct cl_lock_slice *s,
237 const struct cl_lock_descr *d)
239 struct lovsub_lock *lock = cl2lovsub_lock(s);
240 struct lov_lock_link *scan;
241 struct lov_lock *lov;
246 LASSERT(cl_lock_mode_match(d->cld_mode,
247 s->cls_lock->cll_descr.cld_mode));
248 cfs_list_for_each_entry(scan, &lock->lss_parents, lll_list) {
251 lov = scan->lll_super;
252 lovsub_parent_lock(env, lov);
253 rc = lov_sublock_modify(env, lov, lock, d, scan->lll_idx);
254 lovsub_parent_unlock(env, lov);
255 result = result ?: rc;
260 static int lovsub_lock_closure(const struct lu_env *env,
261 const struct cl_lock_slice *slice,
262 struct cl_lock_closure *closure)
264 struct lovsub_lock *sub;
265 struct cl_lock *parent;
266 struct lov_lock_link *scan;
269 LASSERT(cl_lock_is_mutexed(slice->cls_lock));
272 sub = cl2lovsub_lock(slice);
275 cfs_list_for_each_entry(scan, &sub->lss_parents, lll_list) {
276 parent = scan->lll_super->lls_cl.cls_lock;
277 result = cl_lock_closure_build(env, parent, closure);
285 * A helper function for lovsub_lock_delete() that deals with a given parent
288 static int lovsub_lock_delete_one(const struct lu_env *env,
289 struct cl_lock *child, struct lov_lock *lov)
291 struct cl_lock *parent;
295 parent = lov->lls_cl.cls_lock;
296 if (parent->cll_error)
300 switch (parent->cll_state) {
302 /* See LU-1355 for the case that a glimpse lock is
303 * interrupted by signal */
304 LASSERT(parent->cll_flags & CLF_CANCELLED);
308 cl_lock_signal(env, parent);
312 * Here lies a problem: a sub-lock is canceled while top-lock
313 * is being unlocked. Top-lock cannot be moved into CLS_NEW
314 * state, because unlocking has to succeed eventually by
315 * placing lock into CLS_CACHED (or failing it), see
316 * cl_unuse_try(). Nor can top-lock be left in CLS_CACHED
317 * state, because lov maintains an invariant that all
318 * sub-locks exist in CLS_CACHED (this allows cached top-lock
319 * to be reused immediately). Nor can we wait for top-lock
320 * state to change, because this can be synchronous to the
323 * We know for sure that lov_lock_unuse() will be called at
324 * least one more time to finish un-using, so leave a mark on
325 * the top-lock, that will be seen by the next call to
328 if (cl_lock_is_intransit(parent))
329 lov->lls_cancel_race = 1;
333 * if a sub-lock is canceled move its top-lock into CLS_NEW
334 * state to preserve an invariant that a top-lock in
335 * CLS_CACHED is immediately ready for re-use (i.e., has all
336 * sub-locks), and so that next attempt to re-use the top-lock
337 * enqueues missing sub-lock.
339 cl_lock_state_set(env, parent, CLS_NEW);
343 * if last sub-lock is canceled, destroy the top-lock (which
344 * is now `empty') proactively.
346 if (lov->lls_nr_filled == 0) {
347 /* ... but unfortunately, this cannot be done easily,
348 * as cancellation of a top-lock might acquire mutices
349 * of its other sub-locks, violating lock ordering,
350 * see cl_lock_{cancel,delete}() preconditions.
352 * To work around this, the mutex of this sub-lock is
353 * released, top-lock is destroyed, and sub-lock mutex
354 * acquired again. The list of parents has to be
355 * re-scanned from the beginning after this.
357 * Only do this if no mutices other than on @child and
358 * @parent are held by the current thread.
360 * TODO: The lock modal here is too complex, because
361 * the lock may be canceled and deleted by voluntarily:
363 * -> osc_lock_enqueue_wait
364 * -> osc_lock_cancel_wait
366 * -> lovsub_lock_delete
367 * -> cl_lock_cancel/delete
370 * The better choice is to spawn a kernel thread for
373 if (cl_lock_nr_mutexed(env) == 2) {
374 cl_lock_mutex_put(env, child);
375 cl_lock_cancel(env, parent);
376 cl_lock_delete(env, parent);
382 CL_LOCK_DEBUG(D_ERROR, env, parent, "Delete CLS_HELD lock\n");
383 /* falling through */
385 CERROR("Impossible state: %d\n", parent->cll_state);
394 * An implementation of cl_lock_operations::clo_delete() method. This is
395 * invoked in "bottom-to-top" delete, when lock destruction starts from the
396 * sub-lock (e.g, as a result of ldlm lock LRU policy).
398 static void lovsub_lock_delete(const struct lu_env *env,
399 const struct cl_lock_slice *slice)
401 struct cl_lock *child = slice->cls_lock;
402 struct lovsub_lock *sub = cl2lovsub_lock(slice);
405 LASSERT(cl_lock_is_mutexed(child));
409 * Destruction of a sub-lock might take multiple iterations, because
410 * when the last sub-lock of a given top-lock is deleted, top-lock is
411 * canceled proactively, and this requires to release sub-lock
412 * mutex. Once sub-lock mutex has been released, list of its parents
413 * has to be re-scanned from the beginning.
416 struct lov_lock *lov;
417 struct lov_lock_link *scan;
418 struct lov_lock_link *temp;
421 cfs_list_for_each_entry_safe(scan, temp,
422 &sub->lss_parents, lll_list) {
423 lov = scan->lll_super;
424 lovsub_parent_lock(env, lov);
425 lov_lock_unlink(env, scan, sub);
426 restart = lovsub_lock_delete_one(env, child, lov);
427 lovsub_parent_unlock(env, lov);
430 cl_lock_mutex_get(env, child);
438 static int lovsub_lock_print(const struct lu_env *env, void *cookie,
439 lu_printer_t p, const struct cl_lock_slice *slice)
441 struct lovsub_lock *sub = cl2lovsub_lock(slice);
442 struct lov_lock *lov;
443 struct lov_lock_link *scan;
445 cfs_list_for_each_entry(scan, &sub->lss_parents, lll_list) {
446 lov = scan->lll_super;
447 (*p)(env, cookie, "[%d %p ", scan->lll_idx, lov);
449 cl_lock_descr_print(env, cookie, p,
450 &lov->lls_cl.cls_lock->cll_descr);
451 (*p)(env, cookie, "] ");
456 static const struct cl_lock_operations lovsub_lock_ops = {
457 .clo_fini = lovsub_lock_fini,
458 .clo_state = lovsub_lock_state,
459 .clo_delete = lovsub_lock_delete,
460 .clo_modify = lovsub_lock_modify,
461 .clo_closure = lovsub_lock_closure,
462 .clo_weigh = lovsub_lock_weigh,
463 .clo_print = lovsub_lock_print
466 int lovsub_lock_init(const struct lu_env *env, struct cl_object *obj,
467 struct cl_lock *lock, const struct cl_io *io)
469 struct lovsub_lock *lsk;
473 OBD_SLAB_ALLOC_PTR_GFP(lsk, lovsub_lock_kmem, __GFP_IO);
475 CFS_INIT_LIST_HEAD(&lsk->lss_parents);
476 cl_lock_slice_add(lock, &lsk->lss_cl, obj, &lovsub_lock_ops);