4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 only,
8 * as published by the Free Software Foundation.
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License version 2 for more details (a copy is included
14 * in the LICENSE file that accompanied this code).
16 * You should have received a copy of the GNU General Public License
17 * version 2 along with this program; If not, see
18 * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
20 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
21 * CA 95054 USA or visit www.sun.com if you need additional information or
27 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
28 * Use is subject to license terms.
30 * Copyright (c) 2011, 2014, Intel Corporation.
33 * This file is part of Lustre, http://www.lustre.org/
34 * Lustre is a trademark of Sun Microsystems, Inc.
38 #include <linux/sched.h>
39 #include <linux/kthread.h>
41 #include <linux/highmem.h>
42 #include <linux/pagemap.h>
44 #define DEBUG_SUBSYSTEM S_LLITE
46 #include <obd_support.h>
47 #include <lustre_dlm.h>
48 #include "llite_internal.h"
50 #define SA_OMITTED_ENTRY_MAX 8ULL
53 /** negative values are for error cases */
54 SA_ENTRY_INIT = 0, /** init entry */
55 SA_ENTRY_SUCC = 1, /** stat succeed */
56 SA_ENTRY_INVA = 2, /** invalid entry */
59 /* sa_entry is not refcounted: statahead thread allocates it and do async stat,
60 * and in async stat callback ll_statahead_interpret() will add it into
61 * sai_interim_entries, later statahead thread will call sa_handle_callback() to
62 * instantiate entry and move it into sai_entries, and then only scanner process
63 * can access and free it. */
65 /* link into sai_interim_entries or sai_entries */
66 struct list_head se_list;
67 /* link into sai hash table locally */
68 struct list_head se_hash;
69 /* entry index in the sai */
71 /* low layer ldlm lock handle */
75 /* entry size, contains name */
77 /* pointer to async getattr enqueue info */
78 struct md_enqueue_info *se_minfo;
79 /* pointer to the async getattr request */
80 struct ptlrpc_request *se_req;
81 /* pointer to the target inode */
82 struct inode *se_inode;
87 static unsigned int sai_generation = 0;
88 static DEFINE_SPINLOCK(sai_generation_lock);
90 static inline int sa_unhashed(struct sa_entry *entry)
92 return list_empty(&entry->se_hash);
95 /* sa_entry is ready to use */
96 static inline int sa_ready(struct sa_entry *entry)
99 return (entry->se_state != SA_ENTRY_INIT);
102 /* hash value to put in sai_cache */
103 static inline int sa_hash(int val)
105 return val & LL_SA_CACHE_MASK;
108 /* hash entry into sai_cache */
110 sa_rehash(struct ll_statahead_info *sai, struct sa_entry *entry)
112 int i = sa_hash(entry->se_qstr.hash);
114 spin_lock(&sai->sai_cache_lock[i]);
115 list_add_tail(&entry->se_hash, &sai->sai_cache[i]);
116 spin_unlock(&sai->sai_cache_lock[i]);
119 /* unhash entry from sai_cache */
121 sa_unhash(struct ll_statahead_info *sai, struct sa_entry *entry)
123 int i = sa_hash(entry->se_qstr.hash);
125 spin_lock(&sai->sai_cache_lock[i]);
126 list_del_init(&entry->se_hash);
127 spin_unlock(&sai->sai_cache_lock[i]);
130 static inline int agl_should_run(struct ll_statahead_info *sai,
133 return (inode != NULL && S_ISREG(inode->i_mode) && sai->sai_agl_valid);
136 static inline struct ll_inode_info *
137 agl_first_entry(struct ll_statahead_info *sai)
139 return list_entry(sai->sai_agls.next, struct ll_inode_info,
143 /* statahead window is full */
144 static inline int sa_sent_full(struct ll_statahead_info *sai)
146 return atomic_read(&sai->sai_cache_count) >= sai->sai_max;
149 /* got async stat replies */
150 static inline int sa_has_callback(struct ll_statahead_info *sai)
152 return !list_empty(&sai->sai_interim_entries);
155 static inline int agl_list_empty(struct ll_statahead_info *sai)
157 return list_empty(&sai->sai_agls);
161 * (1) hit ratio less than 80%
163 * (2) consecutive miss more than 8
164 * then means low hit.
166 static inline int sa_low_hit(struct ll_statahead_info *sai)
168 return ((sai->sai_hit > 7 && sai->sai_hit < 4 * sai->sai_miss) ||
169 (sai->sai_consecutive_miss > 8));
173 * if the given index is behind of statahead window more than
174 * SA_OMITTED_ENTRY_MAX, then it is old.
176 static inline int is_omitted_entry(struct ll_statahead_info *sai, __u64 index)
178 return ((__u64)sai->sai_max + index + SA_OMITTED_ENTRY_MAX <
182 /* allocate sa_entry and hash it to allow scanner process to find it */
183 static struct sa_entry *
184 sa_alloc(struct ll_statahead_info *sai, __u64 index, const char *name, int len)
186 struct ll_inode_info *lli;
187 struct sa_entry *entry;
192 entry_size = sizeof(struct sa_entry) + (len & ~3) + 4;
193 OBD_ALLOC(entry, entry_size);
194 if (unlikely(entry == NULL))
195 RETURN(ERR_PTR(-ENOMEM));
197 CDEBUG(D_READA, "alloc sa entry %.*s(%p) index "LPU64"\n",
198 len, name, entry, index);
200 entry->se_index = index;
202 entry->se_state = SA_ENTRY_INIT;
203 entry->se_size = entry_size;
204 dname = (char *)entry + sizeof(struct sa_entry);
205 memcpy(dname, name, len);
207 entry->se_qstr.hash = full_name_hash(name, len);
208 entry->se_qstr.len = len;
209 entry->se_qstr.name = dname;
211 lli = ll_i2info(sai->sai_dentry->d_inode);
213 spin_lock(&lli->lli_sa_lock);
214 INIT_LIST_HEAD(&entry->se_list);
215 sa_rehash(sai, entry);
216 spin_unlock(&lli->lli_sa_lock);
218 atomic_inc(&sai->sai_cache_count);
223 /* free sa_entry, which should have been unhashed and not in any list */
224 static void sa_free(struct ll_statahead_info *sai, struct sa_entry *entry)
226 CDEBUG(D_READA, "free sa entry %.*s(%p) index "LPU64"\n",
227 entry->se_qstr.len, entry->se_qstr.name, entry,
230 LASSERT(list_empty(&entry->se_list));
231 LASSERT(sa_unhashed(entry));
233 OBD_FREE(entry, entry->se_size);
234 atomic_dec(&sai->sai_cache_count);
238 * find sa_entry by name, used by directory scanner, lock is not needed because
239 * only scanner can remove the entry from cache.
241 static struct sa_entry *
242 sa_get(struct ll_statahead_info *sai, const struct qstr *qstr)
244 struct sa_entry *entry;
245 int i = sa_hash(qstr->hash);
247 list_for_each_entry(entry, &sai->sai_cache[i], se_hash) {
248 if (entry->se_qstr.hash == qstr->hash &&
249 entry->se_qstr.len == qstr->len &&
250 memcmp(entry->se_qstr.name, qstr->name, qstr->len) == 0)
256 /* unhash and unlink sa_entry, and then free it */
258 sa_kill(struct ll_statahead_info *sai, struct sa_entry *entry)
260 struct ll_inode_info *lli = ll_i2info(sai->sai_dentry->d_inode);
262 LASSERT(!sa_unhashed(entry));
263 LASSERT(!list_empty(&entry->se_list));
264 LASSERT(sa_ready(entry));
266 sa_unhash(sai, entry);
268 spin_lock(&lli->lli_sa_lock);
269 list_del_init(&entry->se_list);
270 spin_unlock(&lli->lli_sa_lock);
272 if (entry->se_inode != NULL)
273 iput(entry->se_inode);
278 /* called by scanner after use, sa_entry will be killed */
280 sa_put(struct ll_statahead_info *sai, struct sa_entry *entry)
282 struct sa_entry *tmp, *next;
284 if (entry != NULL && entry->se_state == SA_ENTRY_SUCC) {
285 struct ll_sb_info *sbi = ll_i2sbi(sai->sai_dentry->d_inode);
288 sai->sai_consecutive_miss = 0;
289 sai->sai_max = min(2 * sai->sai_max, sbi->ll_sa_max);
292 sai->sai_consecutive_miss++;
298 /* kill old completed entries, only scanner process does this, no need
300 list_for_each_entry_safe(tmp, next, &sai->sai_entries, se_list) {
301 if (!is_omitted_entry(sai, tmp->se_index))
306 wake_up(&sai->sai_thread.t_ctl_waitq);
309 /* update state and sort add entry to sai_entries by index, return true if
310 * scanner is waiting on this entry. */
312 __sa_make_ready(struct ll_statahead_info *sai, struct sa_entry *entry, int ret)
315 struct list_head *pos = &sai->sai_entries;
316 __u64 index = entry->se_index;
318 LASSERT(!sa_ready(entry));
319 LASSERT(list_empty(&entry->se_list));
321 list_for_each_entry_reverse(se, &sai->sai_entries, se_list) {
322 if (se->se_index < entry->se_index) {
327 list_add(&entry->se_list, pos);
328 entry->se_state = ret < 0 ? SA_ENTRY_INVA : SA_ENTRY_SUCC;
330 return (index == sai->sai_index_wait);
334 * release resources used in async stat RPC, update entry state and wakeup if
335 * scanner process it waiting on this entry.
338 sa_make_ready(struct ll_statahead_info *sai, struct sa_entry *entry, int ret)
340 struct ll_inode_info *lli = ll_i2info(sai->sai_dentry->d_inode);
341 struct md_enqueue_info *minfo = entry->se_minfo;
342 struct ptlrpc_request *req = entry->se_req;
345 /* release resources used in RPC */
347 entry->se_minfo = NULL;
348 ll_intent_release(&minfo->mi_it);
354 entry->se_req = NULL;
355 ptlrpc_req_finished(req);
358 spin_lock(&lli->lli_sa_lock);
359 wakeup = __sa_make_ready(sai, entry, ret);
360 spin_unlock(&lli->lli_sa_lock);
363 wake_up(&sai->sai_waitq);
366 /* insert inode into the list of sai_agls */
367 static void ll_agl_add(struct ll_statahead_info *sai,
368 struct inode *inode, int index)
370 struct ll_inode_info *child = ll_i2info(inode);
371 struct ll_inode_info *parent = ll_i2info(sai->sai_dentry->d_inode);
374 spin_lock(&child->lli_agl_lock);
375 if (child->lli_agl_index == 0) {
376 child->lli_agl_index = index;
377 spin_unlock(&child->lli_agl_lock);
379 LASSERT(list_empty(&child->lli_agl_list));
382 spin_lock(&parent->lli_agl_lock);
383 if (agl_list_empty(sai))
385 list_add_tail(&child->lli_agl_list, &sai->sai_agls);
386 spin_unlock(&parent->lli_agl_lock);
388 spin_unlock(&child->lli_agl_lock);
392 wake_up(&sai->sai_agl_thread.t_ctl_waitq);
396 static struct ll_statahead_info *ll_sai_alloc(struct dentry *dentry)
398 struct ll_statahead_info *sai;
399 struct ll_inode_info *lli = ll_i2info(dentry->d_inode);
407 sai->sai_dentry = dget(dentry);
408 atomic_set(&sai->sai_refcount, 1);
409 sai->sai_max = LL_SA_RPC_MIN;
411 init_waitqueue_head(&sai->sai_waitq);
412 init_waitqueue_head(&sai->sai_thread.t_ctl_waitq);
413 init_waitqueue_head(&sai->sai_agl_thread.t_ctl_waitq);
415 INIT_LIST_HEAD(&sai->sai_interim_entries);
416 INIT_LIST_HEAD(&sai->sai_entries);
417 INIT_LIST_HEAD(&sai->sai_agls);
419 for (i = 0; i < LL_SA_CACHE_SIZE; i++) {
420 INIT_LIST_HEAD(&sai->sai_cache[i]);
421 spin_lock_init(&sai->sai_cache_lock[i]);
423 atomic_set(&sai->sai_cache_count, 0);
425 spin_lock(&sai_generation_lock);
426 lli->lli_sa_generation = ++sai_generation;
427 if (unlikely(sai_generation == 0))
428 lli->lli_sa_generation = ++sai_generation;
429 spin_unlock(&sai_generation_lock);
435 static inline void ll_sai_free(struct ll_statahead_info *sai)
437 LASSERT(sai->sai_dentry != NULL);
438 dput(sai->sai_dentry);
443 * take refcount of sai if sai for @dir exists, which means statahead is on for
446 static inline struct ll_statahead_info *ll_sai_get(struct inode *dir)
448 struct ll_inode_info *lli = ll_i2info(dir);
449 struct ll_statahead_info *sai = NULL;
451 spin_lock(&lli->lli_sa_lock);
454 atomic_inc(&sai->sai_refcount);
455 spin_unlock(&lli->lli_sa_lock);
461 * put sai refcount after use, if refcount reaches zero, free sai and sa_entries
464 static void ll_sai_put(struct ll_statahead_info *sai)
466 struct ll_inode_info *lli = ll_i2info(sai->sai_dentry->d_inode);
468 if (atomic_dec_and_lock(&sai->sai_refcount, &lli->lli_sa_lock)) {
469 struct sa_entry *entry, *next;
470 struct ll_sb_info *sbi = ll_i2sbi(sai->sai_dentry->d_inode);
473 spin_unlock(&lli->lli_sa_lock);
475 LASSERT(thread_is_stopped(&sai->sai_thread));
476 LASSERT(thread_is_stopped(&sai->sai_agl_thread));
477 LASSERT(sai->sai_sent == sai->sai_replied);
478 LASSERT(!sa_has_callback(sai));
480 list_for_each_entry_safe(entry, next, &sai->sai_entries,
484 LASSERT(atomic_read(&sai->sai_cache_count) == 0);
485 LASSERT(agl_list_empty(sai));
488 atomic_dec(&sbi->ll_sa_running);
492 /* Do NOT forget to drop inode refcount when into sai_agls. */
493 static void ll_agl_trigger(struct inode *inode, struct ll_statahead_info *sai)
495 struct ll_inode_info *lli = ll_i2info(inode);
496 __u64 index = lli->lli_agl_index;
500 LASSERT(list_empty(&lli->lli_agl_list));
502 /* AGL maybe fall behind statahead with one entry */
503 if (is_omitted_entry(sai, index + 1)) {
504 lli->lli_agl_index = 0;
509 /* Someone is in glimpse (sync or async), do nothing. */
510 rc = down_write_trylock(&lli->lli_glimpse_sem);
512 lli->lli_agl_index = 0;
518 * Someone triggered glimpse within 1 sec before.
519 * 1) The former glimpse succeeded with glimpse lock granted by OST, and
520 * if the lock is still cached on client, AGL needs to do nothing. If
521 * it is cancelled by other client, AGL maybe cannot obtaion new lock
522 * for no glimpse callback triggered by AGL.
523 * 2) The former glimpse succeeded, but OST did not grant glimpse lock.
524 * Under such case, it is quite possible that the OST will not grant
525 * glimpse lock for AGL also.
526 * 3) The former glimpse failed, compared with other two cases, it is
527 * relative rare. AGL can ignore such case, and it will not muchly
528 * affect the performance.
530 if (lli->lli_glimpse_time != 0 &&
531 cfs_time_before(cfs_time_shift(-1), lli->lli_glimpse_time)) {
532 up_write(&lli->lli_glimpse_sem);
533 lli->lli_agl_index = 0;
538 CDEBUG(D_READA, "Handling (init) async glimpse: inode = "
539 DFID", idx = "LPU64"\n", PFID(&lli->lli_fid), index);
542 lli->lli_agl_index = 0;
543 lli->lli_glimpse_time = cfs_time_current();
544 up_write(&lli->lli_glimpse_sem);
546 CDEBUG(D_READA, "Handled (init) async glimpse: inode= "
547 DFID", idx = "LPU64", rc = %d\n",
548 PFID(&lli->lli_fid), index, rc);
556 * prepare inode for sa entry, add it into agl list, now sa_entry is ready
557 * to be used by scanner process.
559 static void sa_instantiate(struct ll_statahead_info *sai,
560 struct sa_entry *entry)
562 struct inode *dir = sai->sai_dentry->d_inode;
564 struct md_enqueue_info *minfo;
565 struct lookup_intent *it;
566 struct ptlrpc_request *req;
567 struct mdt_body *body;
571 LASSERT(entry->se_handle != 0);
573 minfo = entry->se_minfo;
576 body = req_capsule_server_get(&req->rq_pill, &RMF_MDT_BODY);
578 GOTO(out, rc = -EFAULT);
580 child = entry->se_inode;
585 LASSERT(fid_is_zero(&minfo->mi_data.op_fid2));
587 /* XXX: No fid in reply, this is probaly cross-ref case.
588 * SA can't handle it yet. */
589 if (body->mbo_valid & OBD_MD_MDS)
590 GOTO(out, rc = -EAGAIN);
595 /* unlinked and re-created with the same name */
596 if (unlikely(!lu_fid_eq(&minfo->mi_data.op_fid2,
598 entry->se_inode = NULL;
604 it->d.lustre.it_lock_handle = entry->se_handle;
605 rc = md_revalidate_lock(ll_i2mdexp(dir), it, ll_inode2fid(dir), NULL);
607 GOTO(out, rc = -EAGAIN);
609 rc = ll_prep_inode(&child, req, dir->i_sb, it);
613 CDEBUG(D_READA, "%s: setting %.*s"DFID" l_data to inode %p\n",
614 ll_get_fsname(child->i_sb, NULL, 0),
615 entry->se_qstr.len, entry->se_qstr.name,
616 PFID(ll_inode2fid(child)), child);
617 ll_set_lock_data(ll_i2sbi(dir)->ll_md_exp, child, it, NULL);
619 entry->se_inode = child;
621 if (agl_should_run(sai, child))
622 ll_agl_add(sai, child, entry->se_index);
627 /* sa_make_ready() will drop ldlm ibits lock refcount by calling
628 * ll_intent_drop_lock() in spite of failures. Do not worry about
629 * calling ll_intent_drop_lock() more than once. */
630 sa_make_ready(sai, entry, rc);
633 /* once there are async stat replies, instantiate sa_entry from replies */
634 static void sa_handle_callback(struct ll_statahead_info *sai)
636 struct ll_inode_info *lli;
638 lli = ll_i2info(sai->sai_dentry->d_inode);
640 while (sa_has_callback(sai)) {
641 struct sa_entry *entry;
643 spin_lock(&lli->lli_sa_lock);
644 if (unlikely(!sa_has_callback(sai))) {
645 spin_unlock(&lli->lli_sa_lock);
648 entry = list_entry(sai->sai_interim_entries.next,
649 struct sa_entry, se_list);
650 list_del_init(&entry->se_list);
651 spin_unlock(&lli->lli_sa_lock);
653 sa_instantiate(sai, entry);
658 * callback for async stat RPC, because this is called in ptlrpcd context, we
659 * only put sa_entry in sai_interim_entries, and wake up statahead thread to
660 * really prepare inode and instantiate sa_entry later.
662 static int ll_statahead_interpret(struct ptlrpc_request *req,
663 struct md_enqueue_info *minfo, int rc)
665 struct lookup_intent *it = &minfo->mi_it;
666 struct inode *dir = minfo->mi_dir;
667 struct ll_inode_info *lli = ll_i2info(dir);
668 struct ll_statahead_info *sai = lli->lli_sai;
669 struct sa_entry *entry = (struct sa_entry *)minfo->mi_cbdata;
674 if (it_disposition(it, DISP_LOOKUP_NEG))
677 /* because statahead thread will wait for all inflight RPC to finish,
678 * sai should be always valid, no need to refcount */
679 LASSERT(sai != NULL);
680 LASSERT(!thread_is_stopped(&sai->sai_thread));
681 LASSERT(entry != NULL);
683 CDEBUG(D_READA, "sa_entry %.*s rc %d\n",
684 entry->se_qstr.len, entry->se_qstr.name, rc);
687 ll_intent_release(it);
691 /* release ibits lock ASAP to avoid deadlock when statahead
692 * thread enqueues lock on parent in readdir and another
693 * process enqueues lock on child with parent lock held, eg.
695 handle = it->d.lustre.it_lock_handle;
696 ll_intent_drop_lock(it);
699 spin_lock(&lli->lli_sa_lock);
701 wakeup = __sa_make_ready(sai, entry, rc);
703 entry->se_minfo = minfo;
704 entry->se_req = ptlrpc_request_addref(req);
705 /* Release the async ibits lock ASAP to avoid deadlock
706 * when statahead thread tries to enqueue lock on parent
707 * for readpage and other tries to enqueue lock on child
708 * with parent's lock held, for example: unlink. */
709 entry->se_handle = handle;
710 wakeup = !sa_has_callback(sai);
711 list_add_tail(&entry->se_list, &sai->sai_interim_entries);
715 wake_up(&sai->sai_thread.t_ctl_waitq);
716 spin_unlock(&lli->lli_sa_lock);
721 /* finish async stat RPC arguments */
722 static void sa_fini_data(struct md_enqueue_info *minfo,
723 struct ldlm_enqueue_info *einfo)
725 LASSERT(minfo && einfo);
727 capa_put(minfo->mi_data.op_capa1);
728 capa_put(minfo->mi_data.op_capa2);
734 * prepare arguments for async stat RPC.
736 * There is race condition between "capa_put" and "ll_statahead_interpret" for
737 * accessing "op_data.op_capa[1,2]" as following:
738 * "capa_put" releases "op_data.op_capa[1,2]"'s reference count after calling
739 * "md_intent_getattr_async". But "ll_statahead_interpret" maybe run first, and
740 * fill "op_data.op_capa[1,2]" as POISON, then cause "capa_put" access invalid
741 * "ocapa". So here reserve "op_data.op_capa[1,2]" in "pcapa" before calling
742 * "md_intent_getattr_async".
744 static int sa_prep_data(struct inode *dir, struct inode *child,
745 struct sa_entry *entry, struct md_enqueue_info **pmi,
746 struct ldlm_enqueue_info **pei,
747 struct obd_capa **pcapa)
749 struct qstr *qstr = &entry->se_qstr;
750 struct md_enqueue_info *minfo;
751 struct ldlm_enqueue_info *einfo;
752 struct md_op_data *op_data;
754 OBD_ALLOC_PTR(einfo);
758 OBD_ALLOC_PTR(minfo);
764 op_data = ll_prep_md_op_data(&minfo->mi_data, dir, child, qstr->name,
765 qstr->len, 0, LUSTRE_OPC_ANY, NULL);
766 if (IS_ERR(op_data)) {
769 return PTR_ERR(op_data);
772 minfo->mi_it.it_op = IT_GETATTR;
773 minfo->mi_dir = igrab(dir);
774 minfo->mi_cb = ll_statahead_interpret;
775 minfo->mi_cbdata = entry;
777 einfo->ei_type = LDLM_IBITS;
778 einfo->ei_mode = it_to_lock_mode(&minfo->mi_it);
779 einfo->ei_cb_bl = ll_md_blocking_ast;
780 einfo->ei_cb_cp = ldlm_completion_ast;
781 einfo->ei_cb_gl = NULL;
782 einfo->ei_cbdata = NULL;
786 pcapa[0] = op_data->op_capa1;
787 pcapa[1] = op_data->op_capa2;
792 /* async stat for file not found in dcache */
793 static int sa_lookup(struct inode *dir, struct sa_entry *entry)
795 struct md_enqueue_info *minfo;
796 struct ldlm_enqueue_info *einfo;
797 struct obd_capa *capas[2];
801 rc = sa_prep_data(dir, NULL, entry, &minfo, &einfo, capas);
805 rc = md_intent_getattr_async(ll_i2mdexp(dir), minfo, einfo);
810 sa_fini_data(minfo, einfo);
817 * async stat for file found in dcache, similar to .revalidate
819 * \retval 1 dentry valid, no RPC sent
820 * \retval 0 dentry invalid, will send async stat RPC
821 * \retval negative number upon error
823 static int sa_revalidate(struct inode *dir, struct sa_entry *entry,
824 struct dentry *dentry)
826 struct inode *inode = dentry->d_inode;
827 struct lookup_intent it = { .it_op = IT_GETATTR,
828 .d.lustre.it_lock_handle = 0 };
829 struct md_enqueue_info *minfo;
830 struct ldlm_enqueue_info *einfo;
831 struct obd_capa *capas[2];
835 if (unlikely(inode == NULL))
838 if (d_mountpoint(dentry))
841 entry->se_inode = igrab(inode);
842 rc = md_revalidate_lock(ll_i2mdexp(dir), &it, ll_inode2fid(inode),
845 entry->se_handle = it.d.lustre.it_lock_handle;
846 ll_intent_release(&it);
850 rc = sa_prep_data(dir, inode, entry, &minfo, &einfo, capas);
852 entry->se_inode = NULL;
857 rc = md_intent_getattr_async(ll_i2mdexp(dir), minfo, einfo);
862 entry->se_inode = NULL;
864 sa_fini_data(minfo, einfo);
870 /* async stat for file with @name */
871 static void sa_statahead(struct dentry *parent, const char *name, int len)
873 struct inode *dir = parent->d_inode;
874 struct ll_inode_info *lli = ll_i2info(dir);
875 struct ll_statahead_info *sai = lli->lli_sai;
876 struct dentry *dentry = NULL;
877 struct sa_entry *entry;
881 entry = sa_alloc(sai, sai->sai_index, name, len);
885 dentry = d_lookup(parent, &entry->se_qstr);
887 rc = sa_lookup(dir, entry);
889 rc = sa_revalidate(dir, entry, dentry);
890 if (rc == 1 && agl_should_run(sai, dentry->d_inode))
891 ll_agl_add(sai, dentry->d_inode, entry->se_index);
898 sa_make_ready(sai, entry, rc);
907 /* async glimpse (agl) thread main function */
908 static int ll_agl_thread(void *arg)
910 struct dentry *parent = (struct dentry *)arg;
911 struct inode *dir = parent->d_inode;
912 struct ll_inode_info *plli = ll_i2info(dir);
913 struct ll_inode_info *clli;
914 struct ll_sb_info *sbi = ll_i2sbi(dir);
915 struct ll_statahead_info *sai;
916 struct ptlrpc_thread *thread;
917 struct l_wait_info lwi = { 0 };
921 sai = ll_sai_get(dir);
922 thread = &sai->sai_agl_thread;
923 thread->t_pid = current_pid();
924 CDEBUG(D_READA, "agl thread started: sai %p, parent %.*s\n",
925 sai, parent->d_name.len, parent->d_name.name);
927 atomic_inc(&sbi->ll_agl_total);
928 spin_lock(&plli->lli_agl_lock);
929 sai->sai_agl_valid = 1;
930 if (thread_is_init(thread))
931 /* If someone else has changed the thread state
932 * (e.g. already changed to SVC_STOPPING), we can't just
933 * blindly overwrite that setting. */
934 thread_set_flags(thread, SVC_RUNNING);
935 spin_unlock(&plli->lli_agl_lock);
936 wake_up(&thread->t_ctl_waitq);
939 l_wait_event(thread->t_ctl_waitq,
940 !agl_list_empty(sai) ||
941 !thread_is_running(thread),
944 if (!thread_is_running(thread))
947 spin_lock(&plli->lli_agl_lock);
948 /* The statahead thread maybe help to process AGL entries,
949 * so check whether list empty again. */
950 if (!agl_list_empty(sai)) {
951 clli = agl_first_entry(sai);
952 list_del_init(&clli->lli_agl_list);
953 spin_unlock(&plli->lli_agl_lock);
954 ll_agl_trigger(&clli->lli_vfs_inode, sai);
956 spin_unlock(&plli->lli_agl_lock);
960 spin_lock(&plli->lli_agl_lock);
961 sai->sai_agl_valid = 0;
962 while (!agl_list_empty(sai)) {
963 clli = agl_first_entry(sai);
964 list_del_init(&clli->lli_agl_list);
965 spin_unlock(&plli->lli_agl_lock);
966 clli->lli_agl_index = 0;
967 iput(&clli->lli_vfs_inode);
968 spin_lock(&plli->lli_agl_lock);
970 thread_set_flags(thread, SVC_STOPPED);
971 spin_unlock(&plli->lli_agl_lock);
972 wake_up(&thread->t_ctl_waitq);
974 CDEBUG(D_READA, "agl thread stopped: sai %p, parent %.*s\n",
975 sai, parent->d_name.len, parent->d_name.name);
979 /* start agl thread */
980 static void ll_start_agl(struct dentry *parent, struct ll_statahead_info *sai)
982 struct ptlrpc_thread *thread = &sai->sai_agl_thread;
983 struct l_wait_info lwi = { 0 };
984 struct ll_inode_info *plli;
985 struct task_struct *task;
988 CDEBUG(D_READA, "start agl thread: sai %p, parent %.*s\n",
989 sai, parent->d_name.len, parent->d_name.name);
991 plli = ll_i2info(parent->d_inode);
992 task = kthread_run(ll_agl_thread, parent,
993 "ll_agl_%u", plli->lli_opendir_pid);
995 CERROR("can't start ll_agl thread, rc: %ld\n", PTR_ERR(task));
996 thread_set_flags(thread, SVC_STOPPED);
1000 l_wait_event(thread->t_ctl_waitq,
1001 thread_is_running(thread) || thread_is_stopped(thread),
1006 /* statahead thread main function */
1007 static int ll_statahead_thread(void *arg)
1009 struct dentry *parent = (struct dentry *)arg;
1010 struct inode *dir = parent->d_inode;
1011 struct ll_inode_info *lli = ll_i2info(dir);
1012 struct ll_sb_info *sbi = ll_i2sbi(dir);
1013 struct ll_statahead_info *sai;
1014 struct ptlrpc_thread *sa_thread;
1015 struct ptlrpc_thread *agl_thread;
1017 struct md_op_data *op_data;
1018 struct ll_dir_chain chain;
1019 struct l_wait_info lwi = { 0 };
1020 struct page *page = NULL;
1025 sai = ll_sai_get(dir);
1026 sa_thread = &sai->sai_thread;
1027 agl_thread = &sai->sai_agl_thread;
1028 sa_thread->t_pid = current_pid();
1029 CDEBUG(D_READA, "statahead thread starting: sai %p, parent %.*s\n",
1030 sai, parent->d_name.len, parent->d_name.name);
1032 op_data = ll_prep_md_op_data(NULL, dir, dir, NULL, 0, 0,
1033 LUSTRE_OPC_ANY, dir);
1034 if (IS_ERR(op_data))
1035 GOTO(out, rc = PTR_ERR(op_data));
1037 op_data->op_max_pages = ll_i2sbi(dir)->ll_md_brw_pages;
1039 if (sbi->ll_flags & LL_SBI_AGL_ENABLED)
1040 ll_start_agl(parent, sai);
1042 atomic_inc(&sbi->ll_sa_total);
1043 spin_lock(&lli->lli_sa_lock);
1044 if (thread_is_init(sa_thread))
1045 /* If someone else has changed the thread state
1046 * (e.g. already changed to SVC_STOPPING), we can't just
1047 * blindly overwrite that setting. */
1048 thread_set_flags(sa_thread, SVC_RUNNING);
1049 spin_unlock(&lli->lli_sa_lock);
1050 wake_up(&sa_thread->t_ctl_waitq);
1052 ll_dir_chain_init(&chain);
1053 while (pos != MDS_DIR_END_OFF && thread_is_running(sa_thread)) {
1054 struct lu_dirpage *dp;
1055 struct lu_dirent *ent;
1057 sai->sai_in_readpage = 1;
1058 page = ll_get_dir_page(dir, op_data, pos, &chain);
1059 sai->sai_in_readpage = 0;
1062 CDEBUG(D_READA, "error reading dir "DFID" at "LPU64
1063 "/"LPU64" opendir_pid = %u: rc = %d\n",
1064 PFID(ll_inode2fid(dir)), pos, sai->sai_index,
1065 lli->lli_opendir_pid, rc);
1069 dp = page_address(page);
1070 for (ent = lu_dirent_start(dp);
1071 ent != NULL && thread_is_running(sa_thread) &&
1073 ent = lu_dirent_next(ent)) {
1078 hash = le64_to_cpu(ent->lde_hash);
1079 if (unlikely(hash < pos))
1081 * Skip until we find target hash value.
1085 namelen = le16_to_cpu(ent->lde_namelen);
1086 if (unlikely(namelen == 0))
1088 * Skip dummy record.
1092 name = ent->lde_name;
1093 if (name[0] == '.') {
1099 } else if (name[1] == '.' && namelen == 2) {
1104 } else if (!sai->sai_ls_all) {
1106 * skip hidden files.
1108 sai->sai_skip_hidden++;
1114 * don't stat-ahead first entry.
1116 if (unlikely(++first == 1))
1119 /* wait for spare statahead window */
1121 l_wait_event(sa_thread->t_ctl_waitq,
1122 !sa_sent_full(sai) ||
1123 sa_has_callback(sai) ||
1124 !agl_list_empty(sai) ||
1125 !thread_is_running(sa_thread),
1128 sa_handle_callback(sai);
1130 spin_lock(&lli->lli_agl_lock);
1131 while (sa_sent_full(sai) &&
1132 !agl_list_empty(sai)) {
1133 struct ll_inode_info *clli;
1135 clli = agl_first_entry(sai);
1136 list_del_init(&clli->lli_agl_list);
1137 spin_unlock(&lli->lli_agl_lock);
1139 ll_agl_trigger(&clli->lli_vfs_inode,
1142 spin_lock(&lli->lli_agl_lock);
1144 spin_unlock(&lli->lli_agl_lock);
1145 } while (sa_sent_full(sai) &&
1146 thread_is_running(sa_thread));
1148 sa_statahead(parent, name, namelen);
1151 pos = le64_to_cpu(dp->ldp_hash_end);
1152 ll_release_page(dir, page,
1153 le32_to_cpu(dp->ldp_flags) & LDF_COLLIDE);
1155 if (sa_low_hit(sai)) {
1157 atomic_inc(&sbi->ll_sa_wrong);
1158 CDEBUG(D_READA, "Statahead for dir "DFID" hit "
1159 "ratio too low: hit/miss "LPU64"/"LPU64
1160 ", sent/replied "LPU64"/"LPU64", stopping "
1161 "statahead thread: pid %d\n",
1162 PFID(&lli->lli_fid), sai->sai_hit,
1163 sai->sai_miss, sai->sai_sent,
1164 sai->sai_replied, current_pid());
1168 ll_dir_chain_fini(&chain);
1169 ll_finish_md_op_data(op_data);
1172 spin_lock(&lli->lli_sa_lock);
1173 thread_set_flags(sa_thread, SVC_STOPPING);
1174 lli->lli_sa_enabled = 0;
1175 spin_unlock(&lli->lli_sa_lock);
1178 /* statahead is finished, but statahead entries need to be cached, wait
1179 * for file release to stop me. */
1180 while (thread_is_running(sa_thread)) {
1181 l_wait_event(sa_thread->t_ctl_waitq,
1182 sa_has_callback(sai) ||
1183 !thread_is_running(sa_thread),
1186 sa_handle_callback(sai);
1191 if (sai->sai_agl_valid) {
1192 spin_lock(&lli->lli_agl_lock);
1193 thread_set_flags(agl_thread, SVC_STOPPING);
1194 spin_unlock(&lli->lli_agl_lock);
1195 wake_up(&agl_thread->t_ctl_waitq);
1197 CDEBUG(D_READA, "stop agl thread: sai %p pid %u\n",
1198 sai, (unsigned int)agl_thread->t_pid);
1199 l_wait_event(agl_thread->t_ctl_waitq,
1200 thread_is_stopped(agl_thread),
1203 /* Set agl_thread flags anyway. */
1204 thread_set_flags(agl_thread, SVC_STOPPED);
1207 /* wait for inflight statahead RPCs to finish, and then we can free sai
1208 * safely because statahead RPC will access sai data */
1209 while (sai->sai_sent != sai->sai_replied) {
1210 /* in case we're not woken up, timeout wait */
1211 lwi = LWI_TIMEOUT(msecs_to_jiffies(MSEC_PER_SEC >> 3),
1213 l_wait_event(sa_thread->t_ctl_waitq,
1214 sai->sai_sent == sai->sai_replied, &lwi);
1217 /* release resources held by statahead RPCs */
1218 sa_handle_callback(sai);
1220 spin_lock(&lli->lli_sa_lock);
1221 thread_set_flags(sa_thread, SVC_STOPPED);
1222 spin_unlock(&lli->lli_sa_lock);
1224 CDEBUG(D_READA, "statahead thread stopped: sai %p, parent %.*s\n",
1225 sai, parent->d_name.len, parent->d_name.name);
1227 wake_up(&sai->sai_waitq);
1228 wake_up(&sa_thread->t_ctl_waitq);
1234 /* authorize opened dir handle @key to statahead */
1235 void ll_authorize_statahead(struct inode *dir, void *key)
1237 struct ll_inode_info *lli = ll_i2info(dir);
1239 spin_lock(&lli->lli_sa_lock);
1240 if (lli->lli_opendir_key == NULL && lli->lli_sai == NULL) {
1242 * if lli_sai is not NULL, it means previous statahead is not
1243 * finished yet, we'd better not start a new statahead for now.
1245 LASSERT(lli->lli_opendir_pid == 0);
1246 lli->lli_opendir_key = key;
1247 lli->lli_opendir_pid = current_pid();
1248 lli->lli_sa_enabled = 1;
1250 spin_unlock(&lli->lli_sa_lock);
1254 * deauthorize opened dir handle @key to statahead, and notify statahead thread
1255 * to quit if it's running.
1257 void ll_deauthorize_statahead(struct inode *dir, void *key)
1259 struct ll_inode_info *lli = ll_i2info(dir);
1260 struct ll_statahead_info *sai;
1262 LASSERT(lli->lli_opendir_key == key);
1263 LASSERT(lli->lli_opendir_pid != 0);
1265 CDEBUG(D_READA, "deauthorize statahead for "DFID"\n",
1266 PFID(&lli->lli_fid));
1268 spin_lock(&lli->lli_sa_lock);
1269 lli->lli_opendir_key = NULL;
1270 lli->lli_opendir_pid = 0;
1271 lli->lli_sa_enabled = 0;
1273 if (sai != NULL && thread_is_running(&sai->sai_thread)) {
1275 * statahead thread may not quit yet because it needs to cache
1276 * entries, now it's time to tell it to quit.
1278 thread_set_flags(&sai->sai_thread, SVC_STOPPING);
1279 wake_up(&sai->sai_thread.t_ctl_waitq);
1281 spin_unlock(&lli->lli_sa_lock);
1286 * not first dirent, or is "."
1288 LS_NOT_FIRST_DE = 0,
1290 * the first non-hidden dirent
1294 * the first hidden dirent, that is "."
1299 /* file is first dirent under @dir */
1300 static int is_first_dirent(struct inode *dir, struct dentry *dentry)
1302 struct ll_dir_chain chain;
1303 struct qstr *target = &dentry->d_name;
1304 struct md_op_data *op_data;
1306 struct page *page = NULL;
1307 int rc = LS_NOT_FIRST_DE;
1311 op_data = ll_prep_md_op_data(NULL, dir, dir, NULL, 0, 0,
1312 LUSTRE_OPC_ANY, dir);
1313 if (IS_ERR(op_data))
1314 RETURN(PTR_ERR(op_data));
1316 *FIXME choose the start offset of the readdir
1318 op_data->op_max_pages = ll_i2sbi(dir)->ll_md_brw_pages;
1320 ll_dir_chain_init(&chain);
1321 page = ll_get_dir_page(dir, op_data, 0, &chain);
1324 struct lu_dirpage *dp;
1325 struct lu_dirent *ent;
1328 struct ll_inode_info *lli = ll_i2info(dir);
1331 CERROR("%s: reading dir "DFID" at "LPU64
1332 "opendir_pid = %u : rc = %d\n",
1333 ll_get_fsname(dir->i_sb, NULL, 0),
1334 PFID(ll_inode2fid(dir)), pos,
1335 lli->lli_opendir_pid, rc);
1339 dp = page_address(page);
1340 for (ent = lu_dirent_start(dp); ent != NULL;
1341 ent = lu_dirent_next(ent)) {
1346 hash = le64_to_cpu(ent->lde_hash);
1347 /* The ll_get_dir_page() can return any page containing
1348 * the given hash which may be not the start hash. */
1349 if (unlikely(hash < pos))
1352 namelen = le16_to_cpu(ent->lde_namelen);
1353 if (unlikely(namelen == 0))
1355 * skip dummy record.
1359 name = ent->lde_name;
1360 if (name[0] == '.') {
1366 else if (name[1] == '.' && namelen == 2)
1377 if (dot_de && target->name[0] != '.') {
1378 CDEBUG(D_READA, "%.*s skip hidden file %.*s\n",
1379 target->len, target->name,
1384 if (target->len != namelen ||
1385 memcmp(target->name, name, namelen) != 0)
1386 rc = LS_NOT_FIRST_DE;
1390 rc = LS_FIRST_DOT_DE;
1392 ll_release_page(dir, page, false);
1395 pos = le64_to_cpu(dp->ldp_hash_end);
1396 if (pos == MDS_DIR_END_OFF) {
1398 * End of directory reached.
1400 ll_release_page(dir, page, false);
1404 * chain is exhausted
1405 * Normal case: continue to the next page.
1407 ll_release_page(dir, page, le32_to_cpu(dp->ldp_flags) &
1409 page = ll_get_dir_page(dir, op_data, pos, &chain);
1414 ll_dir_chain_fini(&chain);
1415 ll_finish_md_op_data(op_data);
1420 * revalidate @dentryp from statahead cache
1422 * \param[in] dir parent directory
1423 * \param[in] sai sai structure
1424 * \param[out] dentryp pointer to dentry which will be revalidated
1425 * \param[in] unplug unplug statahead window only (normally for negative
1427 * \retval 1 on success, dentry is saved in @dentryp
1428 * \retval 0 if revalidation failed (no proper lock on client)
1429 * \retval negative number upon error
1431 static int revalidate_statahead_dentry(struct inode *dir,
1432 struct ll_statahead_info *sai,
1433 struct dentry **dentryp,
1436 struct sa_entry *entry = NULL;
1437 struct l_wait_info lwi = { 0 };
1438 struct ll_dentry_data *ldd;
1439 struct ll_inode_info *lli;
1443 if ((*dentryp)->d_name.name[0] == '.') {
1444 if (sai->sai_ls_all ||
1445 sai->sai_miss_hidden >= sai->sai_skip_hidden) {
1447 * Hidden dentry is the first one, or statahead
1448 * thread does not skip so many hidden dentries
1449 * before "sai_ls_all" enabled as below.
1452 if (!sai->sai_ls_all)
1454 * It maybe because hidden dentry is not
1455 * the first one, "sai_ls_all" was not
1456 * set, then "ls -al" missed. Enable
1457 * "sai_ls_all" for such case.
1459 sai->sai_ls_all = 1;
1462 * Such "getattr" has been skipped before
1463 * "sai_ls_all" enabled as above.
1465 sai->sai_miss_hidden++;
1473 entry = sa_get(sai, &(*dentryp)->d_name);
1475 GOTO(out, rc = -EAGAIN);
1477 /* if statahead is busy in readdir, help it do post-work */
1478 if (!sa_ready(entry) && sai->sai_in_readpage)
1479 sa_handle_callback(sai);
1481 if (!sa_ready(entry)) {
1482 sai->sai_index_wait = entry->se_index;
1483 lwi = LWI_TIMEOUT_INTR(cfs_time_seconds(30), NULL,
1484 LWI_ON_SIGNAL_NOOP, NULL);
1485 rc = l_wait_event(sai->sai_waitq, sa_ready(entry), &lwi);
1488 * entry may not be ready, so it may be used by inflight
1489 * statahead RPC, don't free it.
1492 GOTO(out, rc = -EAGAIN);
1496 if (entry->se_state == SA_ENTRY_SUCC && entry->se_inode != NULL) {
1497 struct inode *inode = entry->se_inode;
1498 struct lookup_intent it = { .it_op = IT_GETATTR,
1499 .d.lustre.it_lock_handle =
1503 rc = md_revalidate_lock(ll_i2mdexp(dir), &it,
1504 ll_inode2fid(inode), &bits);
1506 if ((*dentryp)->d_inode == NULL) {
1507 struct dentry *alias;
1509 alias = ll_splice_alias(inode, *dentryp);
1511 GOTO(out, rc = PTR_ERR(alias));
1513 /* statahead prepared this inode, transfer inode
1514 * refcount from sa_entry to dentry */
1515 entry->se_inode = NULL;
1516 } else if ((*dentryp)->d_inode != inode) {
1517 /* revalidate, but inode is recreated */
1519 "%s: stale dentry %.*s inode "
1520 DFID", statahead inode "DFID
1522 ll_get_fsname((*dentryp)->d_inode->i_sb,
1524 (*dentryp)->d_name.len,
1525 (*dentryp)->d_name.name,
1526 PFID(ll_inode2fid((*dentryp)->d_inode)),
1527 PFID(ll_inode2fid(inode)));
1528 GOTO(out, rc = -ESTALE);
1531 if ((bits & MDS_INODELOCK_LOOKUP) &&
1532 d_lustre_invalid(*dentryp))
1533 d_lustre_revalidate(*dentryp);
1534 ll_intent_release(&it);
1539 * statahead cached sa_entry can be used only once, and will be killed
1540 * right after use, so if lookup/revalidate accessed statahead cache,
1541 * set dentry ldd_sa_generation to parent lli_sa_generation, later if we
1542 * stat this file again, we know we've done statahead before, see
1543 * dentry_may_statahead().
1545 ldd = ll_d2d(*dentryp);
1546 lli = ll_i2info(dir);
1547 /* ldd can be NULL if llite lookup failed. */
1549 ldd->lld_sa_generation = lli->lli_sa_generation;
1556 * start statahead thread
1558 * \param[in] dir parent directory
1559 * \param[in] dentry dentry that triggers statahead, normally the first
1561 * \retval -EAGAIN on success, because when this function is
1562 * called, it's already in lookup call, so client should
1563 * do it itself instead of waiting for statahead thread
1564 * to do it asynchronously.
1565 * \retval negative number upon error
1567 static int start_statahead_thread(struct inode *dir, struct dentry *dentry)
1569 struct ll_inode_info *lli = ll_i2info(dir);
1570 struct ll_statahead_info *sai = NULL;
1571 struct dentry *parent = dentry->d_parent;
1572 struct ptlrpc_thread *thread;
1573 struct l_wait_info lwi = { 0 };
1574 struct task_struct *task;
1578 /* I am the "lli_opendir_pid" owner, only me can set "lli_sai". */
1579 rc = is_first_dirent(dir, dentry);
1580 if (rc == LS_NOT_FIRST_DE)
1581 /* It is not "ls -{a}l" operation, no need statahead for it. */
1582 GOTO(out, rc = -EFAULT);
1584 sai = ll_sai_alloc(parent);
1586 GOTO(out, rc = -ENOMEM);
1588 sai->sai_ls_all = (rc == LS_FIRST_DOT_DE);
1590 /* if current lli_opendir_key was deauthorized, or dir re-opened by
1591 * another process, don't start statahead, otherwise the newly spawned
1592 * statahead thread won't be notified to quit. */
1593 spin_lock(&lli->lli_sa_lock);
1594 if (unlikely(lli->lli_sai != NULL ||
1595 lli->lli_opendir_key == NULL ||
1596 lli->lli_opendir_pid != current->pid)) {
1597 spin_unlock(&lli->lli_sa_lock);
1598 GOTO(out, rc = -EPERM);
1601 spin_unlock(&lli->lli_sa_lock);
1603 atomic_inc(&ll_i2sbi(parent->d_inode)->ll_sa_running);
1605 CDEBUG(D_READA, "start statahead thread: [pid %d] [parent %.*s]\n",
1606 current_pid(), parent->d_name.len, parent->d_name.name);
1608 task = kthread_run(ll_statahead_thread, parent, "ll_sa_%u",
1609 lli->lli_opendir_pid);
1610 thread = &sai->sai_thread;
1613 CERROR("can't start ll_sa thread, rc: %d\n", rc);
1617 l_wait_event(thread->t_ctl_waitq,
1618 thread_is_running(thread) || thread_is_stopped(thread),
1623 * We don't stat-ahead for the first dirent since we are already in
1629 /* once we start statahead thread failed, disable statahead so that
1630 * subsequent stat won't waste time to try it. */
1631 spin_lock(&lli->lli_sa_lock);
1632 lli->lli_sa_enabled = 0;
1633 lli->lli_sai = NULL;
1634 spin_unlock(&lli->lli_sa_lock);
1643 * statahead entry function, this is called when client getattr on a file, it
1644 * will start statahead thread if this is the first dir entry, else revalidate
1645 * dentry from statahead cache.
1647 * \param[in] dir parent directory
1648 * \param[out] dentryp dentry to getattr
1649 * \param[in] unplug unplug statahead window only (normally for negative
1651 * \retval 1 on success
1652 * \retval 0 revalidation from statahead cache failed, caller needs
1653 * to getattr from server directly
1654 * \retval negative number on error, caller often ignores this and
1655 * then getattr from server
1657 int ll_statahead(struct inode *dir, struct dentry **dentryp, bool unplug)
1659 struct ll_statahead_info *sai;
1661 sai = ll_sai_get(dir);
1665 rc = revalidate_statahead_dentry(dir, sai, dentryp, unplug);
1666 CDEBUG(D_READA, "revalidate statahead %.*s: %d.\n",
1667 (*dentryp)->d_name.len, (*dentryp)->d_name.name, rc);
1671 return start_statahead_thread(dir, *dentryp);