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14 * in the LICENSE file that accompanied this code).
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23 * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
24 * Use is subject to license terms.
26 * Copyright (c) 2011, 2017, Intel Corporation.
29 * This file is part of Lustre, http://www.lustre.org/
30 * Lustre is a trademark of Sun Microsystems, Inc.
32 * lustre/ldlm/ldlm_inodebits.c
34 * Author: Peter Braam <braam@clusterfs.com>
35 * Author: Phil Schwan <phil@clusterfs.com>
39 * This file contains implementation of IBITS lock type
41 * IBITS lock type contains a bit mask determining various properties of an
42 * object. The meanings of specific bits are specific to the caller and are
43 * opaque to LDLM code.
45 * Locks with intersecting bitmasks and conflicting lock modes (e.g. LCK_PW)
46 * are considered conflicting. See the lock mode compatibility matrix
50 #define DEBUG_SUBSYSTEM S_LDLM
52 #include <lustre_dlm.h>
53 #include <obd_support.h>
54 #include <lustre_lib.h>
55 #include <obd_class.h>
57 #include "ldlm_internal.h"
59 #ifdef HAVE_SERVER_SUPPORT
62 * Determine if the lock is compatible with all locks on the queue.
64 * If \a work_list is provided, conflicting locks are linked there.
65 * If \a work_list is not provided, we exit this function on first conflict.
67 * \retval 0 if there are conflicting locks in the \a queue
68 * \retval 1 if the lock is compatible to all locks in \a queue
70 * IBITS locks in granted queue are organized in bunches of
71 * same-mode/same-bits locks called "skip lists". The First lock in the
72 * bunch contains a pointer to the end of the bunch. This allows us to
73 * skip an entire bunch when iterating the list in search for conflicting
74 * locks if first lock of the bunch is not conflicting with us.
77 ldlm_inodebits_compat_queue(struct list_head *queue, struct ldlm_lock *req,
78 struct list_head *work_list)
80 struct list_head *tmp;
81 struct ldlm_lock *lock;
82 __u64 req_bits = req->l_policy_data.l_inodebits.bits;
83 __u64 *try_bits = &req->l_policy_data.l_inodebits.try_bits;
88 /* There is no sense in lock with no bits set. Also such a lock
89 * would be compatible with any other bit lock.
90 * Meanwhile that can be true if there were just try_bits and all
91 * are failed, so just exit gracefully and let the caller to care.
93 if ((req_bits | *try_bits) == 0)
96 list_for_each(tmp, queue) {
97 struct list_head *mode_tail;
99 lock = list_entry(tmp, struct ldlm_lock, l_res_link);
101 /* We stop walking the queue if we hit ourselves so we don't
102 * take conflicting locks enqueued after us into account,
103 * or we'd wait forever. */
107 /* last lock in mode group */
108 LASSERT(lock->l_sl_mode.prev != NULL);
109 mode_tail = &list_entry(lock->l_sl_mode.prev, struct ldlm_lock,
110 l_sl_mode)->l_res_link;
112 /* if request lock is not COS_INCOMPAT and COS is disabled,
113 * they are compatible, IOW this request is from a local
114 * transaction on a DNE system. */
115 if (lock->l_req_mode == LCK_COS && !ldlm_is_cos_incompat(req) &&
116 !ldlm_is_cos_enabled(req)) {
117 /* jump to last lock in mode group */
122 /* locks' mode are compatible, bits don't matter */
123 if (lockmode_compat(lock->l_req_mode, req->l_req_mode)) {
124 /* jump to last lock in mode group */
130 struct list_head *head;
132 /* Advance loop cursor to last lock in policy group. */
133 tmp = &list_entry(lock->l_sl_policy.prev,
135 l_sl_policy)->l_res_link;
137 /* New lock's try_bits are filtered out by ibits
138 * of all locks in both granted and waiting queues.
140 *try_bits &= ~(lock->l_policy_data.l_inodebits.bits |
141 lock->l_policy_data.l_inodebits.try_bits);
143 if ((req_bits | *try_bits) == 0)
146 /* The new lock ibits is more preferable than try_bits
147 * of waiting locks so drop conflicting try_bits in
149 * Notice that try_bits of granted locks must be zero.
151 lock->l_policy_data.l_inodebits.try_bits &= ~req_bits;
153 /* Locks with overlapping bits conflict. */
154 if (lock->l_policy_data.l_inodebits.bits & req_bits) {
155 /* COS lock mode has a special compatibility
156 * requirement: it is only compatible with
157 * locks from the same client. */
158 if (lock->l_req_mode == LCK_COS &&
159 !ldlm_is_cos_incompat(req) &&
160 ldlm_is_cos_enabled(req) &&
161 lock->l_client_cookie == req->l_client_cookie)
162 goto not_conflicting;
164 /* Found a conflicting policy group. */
170 /* Add locks of the policy group to @work_list
171 * as blocking locks for @req */
172 if (lock->l_blocking_ast)
173 ldlm_add_ast_work_item(lock, req,
175 head = &lock->l_sl_policy;
176 list_for_each_entry(lock, head, l_sl_policy)
177 if (lock->l_blocking_ast)
178 ldlm_add_ast_work_item(lock,
182 if (tmp == mode_tail)
186 lock = list_entry(tmp, struct ldlm_lock, l_res_link);
187 } /* Loop over policy groups within one mode group. */
188 } /* Loop over mode groups within @queue. */
194 * Process a granting attempt for IBITS lock.
195 * Must be called with ns lock held
197 * This function looks for any conflicts for \a lock in the granted or
198 * waiting queues. The lock is granted if no conflicts are found in
201 int ldlm_process_inodebits_lock(struct ldlm_lock *lock, __u64 *flags,
202 enum ldlm_process_intention intention,
203 enum ldlm_error *err,
204 struct list_head *work_list)
206 struct ldlm_resource *res = lock->l_resource;
207 struct list_head *grant_work = intention == LDLM_PROCESS_ENQUEUE ?
213 LASSERT(!ldlm_is_granted(lock));
214 check_res_locked(res);
216 if (intention == LDLM_PROCESS_RESCAN) {
217 struct list_head *bl_list;
219 if (*flags & LDLM_FL_BLOCK_NOWAIT) {
221 *err = ELDLM_LOCK_WOULDBLOCK;
224 *err = ELDLM_LOCK_ABORTED;
227 LASSERT(lock->l_policy_data.l_inodebits.bits != 0);
229 /* It is possible that some of granted locks was not canceled
230 * but converted and is kept in granted queue. So there is
231 * a window where lock with 'ast_sent' might become granted
232 * again. Meanwhile a new lock may appear in that window and
233 * conflicts with the converted lock so the following scenario
236 * 1) lock1 conflicts with lock2
237 * 2) bl_ast was sent for lock2
238 * 3) lock3 comes and conflicts with lock2 too
239 * 4) no bl_ast sent because lock2->l_bl_ast_sent is 1
240 * 5) lock2 was converted for lock1 but not for lock3
241 * 6) lock1 granted, lock3 still is waiting for lock2, but
242 * there will never be another bl_ast for that
244 * To avoid this scenario the work_list is used below to collect
245 * any blocked locks from granted queue during every reprocess
246 * and bl_ast will be sent if needed.
248 rc = ldlm_inodebits_compat_queue(&res->lr_granted, lock,
251 RETURN(LDLM_ITER_STOP);
252 rc = ldlm_inodebits_compat_queue(&res->lr_waiting, lock, NULL);
254 RETURN(LDLM_ITER_STOP);
256 /* grant also try_bits if any */
257 if (lock->l_policy_data.l_inodebits.try_bits != 0) {
258 lock->l_policy_data.l_inodebits.bits |=
259 lock->l_policy_data.l_inodebits.try_bits;
260 lock->l_policy_data.l_inodebits.try_bits = 0;
261 *flags |= LDLM_FL_LOCK_CHANGED;
263 ldlm_resource_unlink_lock(lock);
264 ldlm_grant_lock(lock, grant_work);
267 RETURN(LDLM_ITER_CONTINUE);
270 rc = ldlm_inodebits_compat_queue(&res->lr_granted, lock, work_list);
271 rc += ldlm_inodebits_compat_queue(&res->lr_waiting, lock, work_list);
274 /* if there were only bits to try and all are conflicting */
275 if ((lock->l_policy_data.l_inodebits.bits |
276 lock->l_policy_data.l_inodebits.try_bits) == 0) {
277 *err = ELDLM_LOCK_WOULDBLOCK;
282 /* grant also all remaining try_bits */
283 if (lock->l_policy_data.l_inodebits.try_bits != 0) {
284 lock->l_policy_data.l_inodebits.bits |=
285 lock->l_policy_data.l_inodebits.try_bits;
286 lock->l_policy_data.l_inodebits.try_bits = 0;
287 *flags |= LDLM_FL_LOCK_CHANGED;
289 LASSERT(lock->l_policy_data.l_inodebits.bits);
290 ldlm_resource_unlink_lock(lock);
291 ldlm_grant_lock(lock, grant_work);
295 RETURN(LDLM_ITER_CONTINUE);
297 #endif /* HAVE_SERVER_SUPPORT */
299 void ldlm_ibits_policy_wire_to_local(const union ldlm_wire_policy_data *wpolicy,
300 union ldlm_policy_data *lpolicy)
302 lpolicy->l_inodebits.bits = wpolicy->l_inodebits.bits;
303 lpolicy->l_inodebits.try_bits = wpolicy->l_inodebits.try_bits;
306 void ldlm_ibits_policy_local_to_wire(const union ldlm_policy_data *lpolicy,
307 union ldlm_wire_policy_data *wpolicy)
309 memset(wpolicy, 0, sizeof(*wpolicy));
310 wpolicy->l_inodebits.bits = lpolicy->l_inodebits.bits;
311 wpolicy->l_inodebits.try_bits = lpolicy->l_inodebits.try_bits;
315 * Attempt to convert already granted IBITS lock with several bits set to
316 * a lock with less bits (downgrade).
318 * Such lock conversion is used to keep lock with non-blocking bits instead of
319 * cancelling it, introduced for better support of DoM files.
321 int ldlm_inodebits_drop(struct ldlm_lock *lock, __u64 to_drop)
325 check_res_locked(lock->l_resource);
327 /* Just return if there are no conflicting bits */
328 if ((lock->l_policy_data.l_inodebits.bits & to_drop) == 0) {
329 LDLM_WARN(lock, "try to drop unset bits %#llx/%#llx",
330 lock->l_policy_data.l_inodebits.bits, to_drop);
335 /* remove lock from a skiplist and put in the new place
336 * according with new inodebits */
337 ldlm_resource_unlink_lock(lock);
338 lock->l_policy_data.l_inodebits.bits &= ~to_drop;
339 ldlm_grant_lock_with_skiplist(lock);
342 EXPORT_SYMBOL(ldlm_inodebits_drop);
344 /* convert single lock */
345 int ldlm_cli_dropbits(struct ldlm_lock *lock, __u64 drop_bits)
347 struct lustre_handle lockh;
354 LASSERT(!lock->l_readers && !lock->l_writers);
356 LDLM_DEBUG(lock, "client lock convert START");
358 ldlm_lock2handle(lock, &lockh);
359 lock_res_and_lock(lock);
360 /* check if all bits are blocked */
361 if (!(lock->l_policy_data.l_inodebits.bits & ~drop_bits)) {
362 unlock_res_and_lock(lock);
363 /* return error to continue with cancel */
364 GOTO(exit, rc = -EINVAL);
367 /* check if no common bits, consider this as successful convert */
368 if (!(lock->l_policy_data.l_inodebits.bits & drop_bits)) {
369 unlock_res_and_lock(lock);
373 /* check if there is race with cancel */
374 if (ldlm_is_canceling(lock) || ldlm_is_cancel(lock)) {
375 unlock_res_and_lock(lock);
376 GOTO(exit, rc = -EINVAL);
379 /* clear cbpending flag early, it is safe to match lock right after
380 * client convert because it is downgrade always.
382 ldlm_clear_cbpending(lock);
383 ldlm_clear_bl_ast(lock);
385 /* If lock is being converted already, check drop bits first */
386 if (ldlm_is_converting(lock)) {
387 /* raced lock convert, lock inodebits are remaining bits
388 * so check if they are conflicting with new convert or not.
390 if (!(lock->l_policy_data.l_inodebits.bits & drop_bits)) {
391 unlock_res_and_lock(lock);
394 /* Otherwise drop new conflicting bits in new convert */
396 ldlm_set_converting(lock);
397 /* from all bits of blocking lock leave only conflicting */
398 drop_bits &= lock->l_policy_data.l_inodebits.bits;
399 /* save them in cancel_bits, so l_blocking_ast will know
400 * which bits from the current lock were dropped. */
401 lock->l_policy_data.l_inodebits.cancel_bits = drop_bits;
402 /* Finally clear these bits in lock ibits */
403 ldlm_inodebits_drop(lock, drop_bits);
404 unlock_res_and_lock(lock);
405 /* Finally call cancel callback for remaining bits only.
406 * It is important to have converting flag during that
407 * so blocking_ast callback can distinguish convert from
410 if (lock->l_blocking_ast)
411 lock->l_blocking_ast(lock, NULL, lock->l_ast_data,
414 /* now notify server about convert */
415 rc = ldlm_cli_convert(lock, &flags);
417 lock_res_and_lock(lock);
418 if (ldlm_is_converting(lock)) {
419 ldlm_clear_converting(lock);
420 ldlm_set_cbpending(lock);
421 ldlm_set_bl_ast(lock);
423 unlock_res_and_lock(lock);
428 LDLM_DEBUG(lock, "client lock convert END");