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, 2013, 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>
40 #include <linux/highmem.h>
41 #include <linux/pagemap.h>
43 #define DEBUG_SUBSYSTEM S_LLITE
45 #include <obd_support.h>
46 #include <lustre_dlm.h>
47 #include "llite_internal.h"
49 #define SA_OMITTED_ENTRY_MAX 8ULL
52 /** negative values are for error cases */
53 SA_ENTRY_INIT = 0, /** init entry */
54 SA_ENTRY_SUCC = 1, /** stat succeed */
55 SA_ENTRY_INVA = 2, /** invalid entry */
58 /* sa_entry is not refcounted: statahead thread allocates it and do async stat,
59 * and in async stat callback ll_statahead_interpret() will add it into
60 * sai_interim_entries, later statahead thread will call sa_handle_callback() to
61 * instantiate entry and move it into sai_entries, and then only scanner process
62 * can access and free it. */
64 /* link into sai_interim_entries or sai_entries */
65 struct list_head se_list;
66 /* link into sai hash table locally */
67 struct list_head se_hash;
68 /* entry index in the sai */
70 /* low layer ldlm lock handle */
74 /* entry size, contains name */
76 /* pointer to async getattr enqueue info */
77 struct md_enqueue_info *se_minfo;
78 /* pointer to the async getattr request */
79 struct ptlrpc_request *se_req;
80 /* pointer to the target inode */
81 struct inode *se_inode;
86 static unsigned int sai_generation = 0;
87 static DEFINE_SPINLOCK(sai_generation_lock);
89 static inline int sa_unhashed(struct sa_entry *entry)
91 return list_empty(&entry->se_hash);
94 /* sa_entry is ready to use */
95 static inline int sa_ready(struct sa_entry *entry)
98 return (entry->se_state != SA_ENTRY_INIT);
101 /* hash value to put in sai_cache */
102 static inline int sa_hash(int val)
104 return val & LL_SA_CACHE_MASK;
107 /* hash entry into sai_cache */
109 sa_rehash(struct ll_statahead_info *sai, struct sa_entry *entry)
111 int i = sa_hash(entry->se_qstr.hash);
113 spin_lock(&sai->sai_cache_lock[i]);
114 list_add_tail(&entry->se_hash, &sai->sai_cache[i]);
115 spin_unlock(&sai->sai_cache_lock[i]);
118 /* unhash entry from sai_cache */
120 sa_unhash(struct ll_statahead_info *sai, struct sa_entry *entry)
122 int i = sa_hash(entry->se_qstr.hash);
124 spin_lock(&sai->sai_cache_lock[i]);
125 list_del_init(&entry->se_hash);
126 spin_unlock(&sai->sai_cache_lock[i]);
129 static inline int agl_should_run(struct ll_statahead_info *sai,
132 return (inode != NULL && S_ISREG(inode->i_mode) && sai->sai_agl_valid);
135 static inline struct ll_inode_info *
136 agl_first_entry(struct ll_statahead_info *sai)
138 return list_entry(sai->sai_agls.next, struct ll_inode_info,
142 /* statahead window is full */
143 static inline int sa_sent_full(struct ll_statahead_info *sai)
145 return atomic_read(&sai->sai_cache_count) >= sai->sai_max;
148 /* got async stat replies */
149 static inline int sa_has_callback(struct ll_statahead_info *sai)
151 return !list_empty(&sai->sai_interim_entries);
154 static inline int agl_list_empty(struct ll_statahead_info *sai)
156 return list_empty(&sai->sai_agls);
160 * (1) hit ratio less than 80%
162 * (2) consecutive miss more than 8
163 * then means low hit.
165 static inline int sa_low_hit(struct ll_statahead_info *sai)
167 return ((sai->sai_hit > 7 && sai->sai_hit < 4 * sai->sai_miss) ||
168 (sai->sai_consecutive_miss > 8));
172 * if the given index is behind of statahead window more than
173 * SA_OMITTED_ENTRY_MAX, then it is old.
175 static inline int is_omitted_entry(struct ll_statahead_info *sai, __u64 index)
177 return ((__u64)sai->sai_max + index + SA_OMITTED_ENTRY_MAX <
181 /* allocate sa_entry and hash it to allow scanner process to find it */
182 static struct sa_entry *
183 sa_alloc(struct ll_statahead_info *sai, __u64 index, const char *name, int len)
185 struct ll_inode_info *lli;
186 struct sa_entry *entry;
191 entry_size = sizeof(struct sa_entry) + (len & ~3) + 4;
192 OBD_ALLOC(entry, entry_size);
193 if (unlikely(entry == NULL))
194 RETURN(ERR_PTR(-ENOMEM));
196 CDEBUG(D_READA, "alloc sa entry %.*s(%p) index "LPU64"\n",
197 len, name, entry, index);
199 entry->se_index = index;
201 entry->se_state = SA_ENTRY_INIT;
202 entry->se_size = entry_size;
203 dname = (char *)entry + sizeof(struct sa_entry);
204 memcpy(dname, name, len);
206 entry->se_qstr.hash = full_name_hash(name, len);
207 entry->se_qstr.len = len;
208 entry->se_qstr.name = dname;
210 lli = ll_i2info(sai->sai_dentry->d_inode);
212 spin_lock(&lli->lli_sa_lock);
213 INIT_LIST_HEAD(&entry->se_list);
214 sa_rehash(sai, entry);
215 spin_unlock(&lli->lli_sa_lock);
217 atomic_inc(&sai->sai_cache_count);
222 /* free sa_entry, which should have been unhashed and not in any list */
223 static void sa_free(struct ll_statahead_info *sai, struct sa_entry *entry)
225 CDEBUG(D_READA, "free sa entry %.*s(%p) index "LPU64"\n",
226 entry->se_qstr.len, entry->se_qstr.name, entry,
229 LASSERT(list_empty(&entry->se_list));
230 LASSERT(sa_unhashed(entry));
232 OBD_FREE(entry, entry->se_size);
233 atomic_dec(&sai->sai_cache_count);
237 * find sa_entry by name, used by directory scanner, lock is not needed because
238 * only scanner can remove the entry from cache.
240 static struct sa_entry *
241 sa_get(struct ll_statahead_info *sai, const struct qstr *qstr)
243 struct sa_entry *entry;
244 int i = sa_hash(qstr->hash);
246 list_for_each_entry(entry, &sai->sai_cache[i], se_hash) {
247 if (entry->se_qstr.hash == qstr->hash &&
248 entry->se_qstr.len == qstr->len &&
249 memcmp(entry->se_qstr.name, qstr->name, qstr->len) == 0)
255 /* unhash and unlink sa_entry, and then free it */
257 sa_kill(struct ll_statahead_info *sai, struct sa_entry *entry)
259 struct ll_inode_info *lli = ll_i2info(sai->sai_dentry->d_inode);
261 LASSERT(!sa_unhashed(entry));
262 LASSERT(!list_empty(&entry->se_list));
263 LASSERT(sa_ready(entry));
265 sa_unhash(sai, entry);
267 spin_lock(&lli->lli_sa_lock);
268 list_del_init(&entry->se_list);
269 spin_unlock(&lli->lli_sa_lock);
271 if (entry->se_inode != NULL)
272 iput(entry->se_inode);
277 /* called by scanner after use, sa_entry will be killed */
279 sa_put(struct ll_statahead_info *sai, struct sa_entry *entry)
281 struct sa_entry *tmp, *next;
283 if (entry != NULL && entry->se_state == SA_ENTRY_SUCC) {
284 struct ll_sb_info *sbi = ll_i2sbi(sai->sai_dentry->d_inode);
287 sai->sai_consecutive_miss = 0;
288 sai->sai_max = min(2 * sai->sai_max, sbi->ll_sa_max);
291 sai->sai_consecutive_miss++;
297 /* kill old completed entries, only scanner process does this, no need
299 list_for_each_entry_safe(tmp, next, &sai->sai_entries, se_list) {
300 if (!is_omitted_entry(sai, tmp->se_index))
305 wake_up(&sai->sai_thread.t_ctl_waitq);
308 /* update state and sort add entry to sai_entries by index, return true if
309 * scanner is waiting on this entry. */
311 __sa_make_ready(struct ll_statahead_info *sai, struct sa_entry *entry, int ret)
314 struct list_head *pos = &sai->sai_entries;
316 LASSERT(!sa_ready(entry));
317 LASSERT(list_empty(&entry->se_list));
319 entry->se_state = ret < 0 ? SA_ENTRY_INVA : SA_ENTRY_SUCC;
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);
329 return (entry->se_index == sai->sai_index_wait);
333 * release resources used in async stat RPC, update entry state and wakeup if
334 * scanner process it waiting on this entry.
337 sa_make_ready(struct ll_statahead_info *sai, struct sa_entry *entry, int ret)
339 struct ll_inode_info *lli = ll_i2info(sai->sai_dentry->d_inode);
340 struct md_enqueue_info *minfo = entry->se_minfo;
341 struct ptlrpc_request *req = entry->se_req;
344 /* release resources used in RPC */
346 entry->se_minfo = NULL;
347 ll_intent_release(&minfo->mi_it);
353 entry->se_req = NULL;
354 ptlrpc_req_finished(req);
357 spin_lock(&lli->lli_sa_lock);
358 wakeup = __sa_make_ready(sai, entry, ret);
359 spin_unlock(&lli->lli_sa_lock);
362 wake_up(&sai->sai_waitq);
365 /* insert inode into the list of sai_agls */
366 static void ll_agl_add(struct ll_statahead_info *sai,
367 struct inode *inode, int index)
369 struct ll_inode_info *child = ll_i2info(inode);
370 struct ll_inode_info *parent = ll_i2info(sai->sai_dentry->d_inode);
373 spin_lock(&child->lli_agl_lock);
374 if (child->lli_agl_index == 0) {
375 child->lli_agl_index = index;
376 spin_unlock(&child->lli_agl_lock);
378 LASSERT(list_empty(&child->lli_agl_list));
381 spin_lock(&parent->lli_agl_lock);
382 if (agl_list_empty(sai))
384 list_add_tail(&child->lli_agl_list, &sai->sai_agls);
385 spin_unlock(&parent->lli_agl_lock);
387 spin_unlock(&child->lli_agl_lock);
391 wake_up(&sai->sai_agl_thread.t_ctl_waitq);
395 static struct ll_statahead_info *ll_sai_alloc(struct dentry *dentry)
397 struct ll_statahead_info *sai;
398 struct ll_inode_info *lli = ll_i2info(dentry->d_inode);
406 sai->sai_dentry = dget(dentry);
407 atomic_set(&sai->sai_refcount, 1);
408 sai->sai_max = LL_SA_RPC_MIN;
410 init_waitqueue_head(&sai->sai_waitq);
411 init_waitqueue_head(&sai->sai_thread.t_ctl_waitq);
412 init_waitqueue_head(&sai->sai_agl_thread.t_ctl_waitq);
414 INIT_LIST_HEAD(&sai->sai_interim_entries);
415 INIT_LIST_HEAD(&sai->sai_entries);
416 INIT_LIST_HEAD(&sai->sai_agls);
418 for (i = 0; i < LL_SA_CACHE_SIZE; i++) {
419 INIT_LIST_HEAD(&sai->sai_cache[i]);
420 spin_lock_init(&sai->sai_cache_lock[i]);
422 atomic_set(&sai->sai_cache_count, 0);
424 spin_lock(&sai_generation_lock);
425 lli->lli_sa_generation = ++sai_generation;
426 if (unlikely(sai_generation == 0))
427 lli->lli_sa_generation = ++sai_generation;
428 spin_unlock(&sai_generation_lock);
434 static inline void ll_sai_free(struct ll_statahead_info *sai)
436 LASSERT(sai->sai_dentry != NULL);
437 dput(sai->sai_dentry);
442 * take refcount of sai if sai for @dir exists, which means statahead is on for
445 static inline struct ll_statahead_info *ll_sai_get(struct inode *dir)
447 struct ll_inode_info *lli = ll_i2info(dir);
448 struct ll_statahead_info *sai = NULL;
450 spin_lock(&lli->lli_sa_lock);
453 atomic_inc(&sai->sai_refcount);
454 spin_unlock(&lli->lli_sa_lock);
460 * put sai refcount after use, if refcount reaches zero, free sai and sa_entries
463 static void ll_sai_put(struct ll_statahead_info *sai)
465 struct ll_inode_info *lli = ll_i2info(sai->sai_dentry->d_inode);
467 if (atomic_dec_and_lock(&sai->sai_refcount, &lli->lli_sa_lock)) {
468 struct sa_entry *entry, *next;
469 struct ll_sb_info *sbi = ll_i2sbi(sai->sai_dentry->d_inode);
472 spin_unlock(&lli->lli_sa_lock);
474 LASSERT(thread_is_stopped(&sai->sai_thread));
475 LASSERT(thread_is_stopped(&sai->sai_agl_thread));
476 LASSERT(sai->sai_sent == sai->sai_replied);
477 LASSERT(!sa_has_callback(sai));
479 list_for_each_entry_safe(entry, next, &sai->sai_entries,
483 LASSERT(atomic_read(&sai->sai_cache_count) == 0);
484 LASSERT(agl_list_empty(sai));
487 atomic_dec(&sbi->ll_sa_running);
491 /* Do NOT forget to drop inode refcount when into sai_agls. */
492 static void ll_agl_trigger(struct inode *inode, struct ll_statahead_info *sai)
494 struct ll_inode_info *lli = ll_i2info(inode);
495 __u64 index = lli->lli_agl_index;
499 LASSERT(list_empty(&lli->lli_agl_list));
501 /* AGL maybe fall behind statahead with one entry */
502 if (is_omitted_entry(sai, index + 1)) {
503 lli->lli_agl_index = 0;
508 /* Someone is in glimpse (sync or async), do nothing. */
509 rc = down_write_trylock(&lli->lli_glimpse_sem);
511 lli->lli_agl_index = 0;
517 * Someone triggered glimpse within 1 sec before.
518 * 1) The former glimpse succeeded with glimpse lock granted by OST, and
519 * if the lock is still cached on client, AGL needs to do nothing. If
520 * it is cancelled by other client, AGL maybe cannot obtaion new lock
521 * for no glimpse callback triggered by AGL.
522 * 2) The former glimpse succeeded, but OST did not grant glimpse lock.
523 * Under such case, it is quite possible that the OST will not grant
524 * glimpse lock for AGL also.
525 * 3) The former glimpse failed, compared with other two cases, it is
526 * relative rare. AGL can ignore such case, and it will not muchly
527 * affect the performance.
529 if (lli->lli_glimpse_time != 0 &&
530 cfs_time_before(cfs_time_shift(-1), lli->lli_glimpse_time)) {
531 up_write(&lli->lli_glimpse_sem);
532 lli->lli_agl_index = 0;
537 CDEBUG(D_READA, "Handling (init) async glimpse: inode = "
538 DFID", idx = "LPU64"\n", PFID(&lli->lli_fid), index);
541 lli->lli_agl_index = 0;
542 lli->lli_glimpse_time = cfs_time_current();
543 up_write(&lli->lli_glimpse_sem);
545 CDEBUG(D_READA, "Handled (init) async glimpse: inode= "
546 DFID", idx = "LPU64", rc = %d\n",
547 PFID(&lli->lli_fid), index, rc);
555 * prepare inode for sa entry, add it into agl list, now sa_entry is ready
556 * to be used by scanner process.
558 static void sa_instantiate(struct ll_statahead_info *sai,
559 struct sa_entry *entry)
561 struct inode *dir = sai->sai_dentry->d_inode;
563 struct md_enqueue_info *minfo;
564 struct lookup_intent *it;
565 struct ptlrpc_request *req;
566 struct mdt_body *body;
570 LASSERT(entry->se_handle != 0);
572 minfo = entry->se_minfo;
575 body = req_capsule_server_get(&req->rq_pill, &RMF_MDT_BODY);
577 GOTO(out, rc = -EFAULT);
579 child = entry->se_inode;
584 LASSERT(fid_is_zero(&minfo->mi_data.op_fid2));
586 /* XXX: No fid in reply, this is probaly cross-ref case.
587 * SA can't handle it yet. */
588 if (body->mbo_valid & OBD_MD_MDS)
589 GOTO(out, rc = -EAGAIN);
594 /* unlinked and re-created with the same name */
595 if (unlikely(!lu_fid_eq(&minfo->mi_data.op_fid2,
597 entry->se_inode = NULL;
603 it->d.lustre.it_lock_handle = entry->se_handle;
604 rc = md_revalidate_lock(ll_i2mdexp(dir), it, ll_inode2fid(dir), NULL);
606 GOTO(out, rc = -EAGAIN);
608 rc = ll_prep_inode(&child, req, dir->i_sb, it);
612 CDEBUG(D_READA, "%s: setting %.*s"DFID" l_data to inode %p\n",
613 ll_get_fsname(child->i_sb, NULL, 0),
614 entry->se_qstr.len, entry->se_qstr.name,
615 PFID(ll_inode2fid(child)), child);
616 ll_set_lock_data(ll_i2sbi(dir)->ll_md_exp, child, it, NULL);
618 entry->se_inode = child;
620 if (agl_should_run(sai, child))
621 ll_agl_add(sai, child, entry->se_index);
626 /* sa_make_ready() will drop ldlm ibits lock refcount by calling
627 * ll_intent_drop_lock() in spite of failures. Do not worry about
628 * calling ll_intent_drop_lock() more than once. */
629 sa_make_ready(sai, entry, rc);
632 /* once there are async stat replies, instantiate sa_entry from replies */
633 static void sa_handle_callback(struct ll_statahead_info *sai)
635 struct ll_inode_info *lli;
637 lli = ll_i2info(sai->sai_dentry->d_inode);
639 while (sa_has_callback(sai)) {
640 struct sa_entry *entry;
642 spin_lock(&lli->lli_sa_lock);
643 if (unlikely(!sa_has_callback(sai))) {
644 spin_unlock(&lli->lli_sa_lock);
647 entry = list_entry(sai->sai_interim_entries.next,
648 struct sa_entry, se_list);
649 list_del_init(&entry->se_list);
650 spin_unlock(&lli->lli_sa_lock);
652 sa_instantiate(sai, entry);
657 * callback for async stat RPC, because this is called in ptlrpcd context, we
658 * only put sa_entry in sai_interim_entries, and wake up statahead thread to
659 * really prepare inode and instantiate sa_entry later.
661 static int ll_statahead_interpret(struct ptlrpc_request *req,
662 struct md_enqueue_info *minfo, int rc)
664 struct lookup_intent *it = &minfo->mi_it;
665 struct inode *dir = minfo->mi_dir;
666 struct ll_inode_info *lli = ll_i2info(dir);
667 struct ll_statahead_info *sai = lli->lli_sai;
668 struct sa_entry *entry = (struct sa_entry *)minfo->mi_cbdata;
673 if (it_disposition(it, DISP_LOOKUP_NEG))
676 /* because statahead thread will wait for all inflight RPC to finish,
677 * sai should be always valid, no need to refcount */
678 LASSERT(sai != NULL);
679 LASSERT(!thread_is_stopped(&sai->sai_thread));
680 LASSERT(entry != NULL);
682 CDEBUG(D_READA, "sa_entry %.*s rc %d\n",
683 entry->se_qstr.len, entry->se_qstr.name, rc);
686 ll_intent_release(it);
690 /* release ibits lock ASAP to avoid deadlock when statahead
691 * thread enqueues lock on parent in readdir and another
692 * process enqueues lock on child with parent lock held, eg.
694 handle = it->d.lustre.it_lock_handle;
695 ll_intent_drop_lock(it);
698 spin_lock(&lli->lli_sa_lock);
700 wakeup = __sa_make_ready(sai, entry, rc);
702 entry->se_minfo = minfo;
703 entry->se_req = ptlrpc_request_addref(req);
704 /* Release the async ibits lock ASAP to avoid deadlock
705 * when statahead thread tries to enqueue lock on parent
706 * for readpage and other tries to enqueue lock on child
707 * with parent's lock held, for example: unlink. */
708 entry->se_handle = handle;
709 wakeup = !sa_has_callback(sai);
710 list_add_tail(&entry->se_list, &sai->sai_interim_entries);
714 wake_up(&sai->sai_thread.t_ctl_waitq);
715 spin_unlock(&lli->lli_sa_lock);
720 /* finish async stat RPC arguments */
721 static void sa_fini_data(struct md_enqueue_info *minfo,
722 struct ldlm_enqueue_info *einfo)
724 LASSERT(minfo && einfo);
726 capa_put(minfo->mi_data.op_capa1);
727 capa_put(minfo->mi_data.op_capa2);
733 * prepare arguments for async stat RPC.
735 * There is race condition between "capa_put" and "ll_statahead_interpret" for
736 * accessing "op_data.op_capa[1,2]" as following:
737 * "capa_put" releases "op_data.op_capa[1,2]"'s reference count after calling
738 * "md_intent_getattr_async". But "ll_statahead_interpret" maybe run first, and
739 * fill "op_data.op_capa[1,2]" as POISON, then cause "capa_put" access invalid
740 * "ocapa". So here reserve "op_data.op_capa[1,2]" in "pcapa" before calling
741 * "md_intent_getattr_async".
743 static int sa_prep_data(struct inode *dir, struct inode *child,
744 struct sa_entry *entry, struct md_enqueue_info **pmi,
745 struct ldlm_enqueue_info **pei,
746 struct obd_capa **pcapa)
748 struct qstr *qstr = &entry->se_qstr;
749 struct md_enqueue_info *minfo;
750 struct ldlm_enqueue_info *einfo;
751 struct md_op_data *op_data;
753 OBD_ALLOC_PTR(einfo);
757 OBD_ALLOC_PTR(minfo);
763 op_data = ll_prep_md_op_data(&minfo->mi_data, dir, child, qstr->name,
764 qstr->len, 0, LUSTRE_OPC_ANY, NULL);
765 if (IS_ERR(op_data)) {
768 return PTR_ERR(op_data);
771 minfo->mi_it.it_op = IT_GETATTR;
772 minfo->mi_dir = igrab(dir);
773 minfo->mi_cb = ll_statahead_interpret;
774 minfo->mi_cbdata = entry;
776 einfo->ei_type = LDLM_IBITS;
777 einfo->ei_mode = it_to_lock_mode(&minfo->mi_it);
778 einfo->ei_cb_bl = ll_md_blocking_ast;
779 einfo->ei_cb_cp = ldlm_completion_ast;
780 einfo->ei_cb_gl = NULL;
781 einfo->ei_cbdata = NULL;
785 pcapa[0] = op_data->op_capa1;
786 pcapa[1] = op_data->op_capa2;
791 /* async stat for file not found in dcache */
792 static int sa_lookup(struct inode *dir, struct sa_entry *entry)
794 struct md_enqueue_info *minfo;
795 struct ldlm_enqueue_info *einfo;
796 struct obd_capa *capas[2];
800 rc = sa_prep_data(dir, NULL, entry, &minfo, &einfo, capas);
804 rc = md_intent_getattr_async(ll_i2mdexp(dir), minfo, einfo);
809 sa_fini_data(minfo, einfo);
816 * async stat for file found in dcache, similar to .revalidate
818 * \retval 1 dentry valid, no RPC sent
819 * \retval 0 dentry invalid, will send async stat RPC
820 * \retval negative number upon error
822 static int sa_revalidate(struct inode *dir, struct sa_entry *entry,
823 struct dentry *dentry)
825 struct inode *inode = dentry->d_inode;
826 struct lookup_intent it = { .it_op = IT_GETATTR,
827 .d.lustre.it_lock_handle = 0 };
828 struct md_enqueue_info *minfo;
829 struct ldlm_enqueue_info *einfo;
830 struct obd_capa *capas[2];
834 if (unlikely(inode == NULL))
837 if (d_mountpoint(dentry))
840 entry->se_inode = igrab(inode);
841 rc = md_revalidate_lock(ll_i2mdexp(dir), &it, ll_inode2fid(inode),
844 entry->se_handle = it.d.lustre.it_lock_handle;
845 ll_intent_release(&it);
849 rc = sa_prep_data(dir, inode, entry, &minfo, &einfo, capas);
851 entry->se_inode = NULL;
856 rc = md_intent_getattr_async(ll_i2mdexp(dir), minfo, einfo);
861 entry->se_inode = NULL;
863 sa_fini_data(minfo, einfo);
869 /* async stat for file with @name */
870 static void sa_statahead(struct dentry *parent, const char *name, int len)
872 struct inode *dir = parent->d_inode;
873 struct ll_inode_info *lli = ll_i2info(dir);
874 struct ll_statahead_info *sai = lli->lli_sai;
875 struct dentry *dentry = NULL;
876 struct sa_entry *entry;
880 entry = sa_alloc(sai, sai->sai_index, name, len);
884 dentry = d_lookup(parent, &entry->se_qstr);
886 rc = sa_lookup(dir, entry);
888 rc = sa_revalidate(dir, entry, dentry);
889 if (rc == 1 && agl_should_run(sai, dentry->d_inode))
890 ll_agl_add(sai, dentry->d_inode, entry->se_index);
897 sa_make_ready(sai, entry, rc);
906 /* async glimpse (agl) thread main function */
907 static int ll_agl_thread(void *arg)
909 struct dentry *parent = (struct dentry *)arg;
910 struct inode *dir = parent->d_inode;
911 struct ll_inode_info *plli = ll_i2info(dir);
912 struct ll_inode_info *clli;
913 struct ll_sb_info *sbi = ll_i2sbi(dir);
914 struct ll_statahead_info *sai;
915 struct ptlrpc_thread *thread;
916 struct l_wait_info lwi = { 0 };
920 sai = ll_sai_get(dir);
921 thread = &sai->sai_agl_thread;
922 thread->t_pid = current_pid();
923 CDEBUG(D_READA, "agl thread started: sai %p, parent %.*s\n",
924 sai, parent->d_name.len, parent->d_name.name);
926 atomic_inc(&sbi->ll_agl_total);
927 spin_lock(&plli->lli_agl_lock);
928 sai->sai_agl_valid = 1;
929 if (thread_is_init(thread))
930 /* If someone else has changed the thread state
931 * (e.g. already changed to SVC_STOPPING), we can't just
932 * blindly overwrite that setting. */
933 thread_set_flags(thread, SVC_RUNNING);
934 spin_unlock(&plli->lli_agl_lock);
935 wake_up(&thread->t_ctl_waitq);
938 l_wait_event(thread->t_ctl_waitq,
939 !agl_list_empty(sai) ||
940 !thread_is_running(thread),
943 if (!thread_is_running(thread))
946 spin_lock(&plli->lli_agl_lock);
947 /* The statahead thread maybe help to process AGL entries,
948 * so check whether list empty again. */
949 if (!agl_list_empty(sai)) {
950 clli = agl_first_entry(sai);
951 list_del_init(&clli->lli_agl_list);
952 spin_unlock(&plli->lli_agl_lock);
953 ll_agl_trigger(&clli->lli_vfs_inode, sai);
955 spin_unlock(&plli->lli_agl_lock);
959 spin_lock(&plli->lli_agl_lock);
960 sai->sai_agl_valid = 0;
961 while (!agl_list_empty(sai)) {
962 clli = agl_first_entry(sai);
963 list_del_init(&clli->lli_agl_list);
964 spin_unlock(&plli->lli_agl_lock);
965 clli->lli_agl_index = 0;
966 iput(&clli->lli_vfs_inode);
967 spin_lock(&plli->lli_agl_lock);
969 thread_set_flags(thread, SVC_STOPPED);
970 spin_unlock(&plli->lli_agl_lock);
971 wake_up(&thread->t_ctl_waitq);
973 CDEBUG(D_READA, "agl thread stopped: sai %p, parent %.*s\n",
974 sai, parent->d_name.len, parent->d_name.name);
978 /* start agl thread */
979 static void ll_start_agl(struct dentry *parent, struct ll_statahead_info *sai)
981 struct ptlrpc_thread *thread = &sai->sai_agl_thread;
982 struct l_wait_info lwi = { 0 };
983 struct ll_inode_info *plli;
984 struct task_struct *task;
987 CDEBUG(D_READA, "start agl thread: sai %p, parent %.*s\n",
988 sai, parent->d_name.len, parent->d_name.name);
990 plli = ll_i2info(parent->d_inode);
991 task = kthread_run(ll_agl_thread, parent,
992 "ll_agl_%u", plli->lli_opendir_pid);
994 CERROR("can't start ll_agl thread, rc: %ld\n", PTR_ERR(task));
995 thread_set_flags(thread, SVC_STOPPED);
999 l_wait_event(thread->t_ctl_waitq,
1000 thread_is_running(thread) || thread_is_stopped(thread),
1005 /* statahead thread main function */
1006 static int ll_statahead_thread(void *arg)
1008 struct dentry *parent = (struct dentry *)arg;
1009 struct inode *dir = parent->d_inode;
1010 struct ll_inode_info *lli = ll_i2info(dir);
1011 struct ll_sb_info *sbi = ll_i2sbi(dir);
1012 struct ll_statahead_info *sai;
1013 struct ptlrpc_thread *sa_thread;
1014 struct ptlrpc_thread *agl_thread;
1016 struct md_op_data *op_data;
1017 struct ll_dir_chain chain;
1018 struct l_wait_info lwi = { 0 };
1019 struct page *page = NULL;
1024 sai = ll_sai_get(dir);
1025 sa_thread = &sai->sai_thread;
1026 agl_thread = &sai->sai_agl_thread;
1027 sa_thread->t_pid = current_pid();
1028 CDEBUG(D_READA, "statahead thread starting: sai %p, parent %.*s\n",
1029 sai, parent->d_name.len, parent->d_name.name);
1031 op_data = ll_prep_md_op_data(NULL, dir, dir, NULL, 0, 0,
1032 LUSTRE_OPC_ANY, dir);
1033 if (IS_ERR(op_data))
1034 GOTO(out, rc = PTR_ERR(op_data));
1036 op_data->op_max_pages = ll_i2sbi(dir)->ll_md_brw_pages;
1038 if (sbi->ll_flags & LL_SBI_AGL_ENABLED)
1039 ll_start_agl(parent, sai);
1041 atomic_inc(&sbi->ll_sa_total);
1042 spin_lock(&lli->lli_sa_lock);
1043 if (thread_is_init(sa_thread))
1044 /* If someone else has changed the thread state
1045 * (e.g. already changed to SVC_STOPPING), we can't just
1046 * blindly overwrite that setting. */
1047 thread_set_flags(sa_thread, SVC_RUNNING);
1048 spin_unlock(&lli->lli_sa_lock);
1049 wake_up(&sa_thread->t_ctl_waitq);
1051 ll_dir_chain_init(&chain);
1052 while (pos != MDS_DIR_END_OFF && thread_is_running(sa_thread)) {
1053 struct lu_dirpage *dp;
1054 struct lu_dirent *ent;
1056 sai->sai_in_readpage = 1;
1057 page = ll_get_dir_page(dir, op_data, pos, &chain);
1058 sai->sai_in_readpage = 0;
1061 CDEBUG(D_READA, "error reading dir "DFID" at "LPU64
1062 "/"LPU64" opendir_pid = %u: rc = %d\n",
1063 PFID(ll_inode2fid(dir)), pos, sai->sai_index,
1064 lli->lli_opendir_pid, rc);
1068 dp = page_address(page);
1069 for (ent = lu_dirent_start(dp);
1070 ent != NULL && thread_is_running(sa_thread) &&
1072 ent = lu_dirent_next(ent)) {
1077 hash = le64_to_cpu(ent->lde_hash);
1078 if (unlikely(hash < pos))
1080 * Skip until we find target hash value.
1084 namelen = le16_to_cpu(ent->lde_namelen);
1085 if (unlikely(namelen == 0))
1087 * Skip dummy record.
1091 name = ent->lde_name;
1092 if (name[0] == '.') {
1098 } else if (name[1] == '.' && namelen == 2) {
1103 } else if (!sai->sai_ls_all) {
1105 * skip hidden files.
1107 sai->sai_skip_hidden++;
1113 * don't stat-ahead first entry.
1115 if (unlikely(++first == 1))
1118 /* wait for spare statahead window */
1120 l_wait_event(sa_thread->t_ctl_waitq,
1121 !sa_sent_full(sai) ||
1122 sa_has_callback(sai) ||
1123 !agl_list_empty(sai) ||
1124 !thread_is_running(sa_thread),
1127 sa_handle_callback(sai);
1129 spin_lock(&lli->lli_agl_lock);
1130 while (sa_sent_full(sai) &&
1131 !agl_list_empty(sai)) {
1132 struct ll_inode_info *clli;
1134 clli = agl_first_entry(sai);
1135 list_del_init(&clli->lli_agl_list);
1136 spin_unlock(&lli->lli_agl_lock);
1138 ll_agl_trigger(&clli->lli_vfs_inode,
1141 spin_lock(&lli->lli_agl_lock);
1143 spin_unlock(&lli->lli_agl_lock);
1144 } while (sa_sent_full(sai) &&
1145 thread_is_running(sa_thread));
1147 sa_statahead(parent, name, namelen);
1150 pos = le64_to_cpu(dp->ldp_hash_end);
1151 ll_release_page(dir, page,
1152 le32_to_cpu(dp->ldp_flags) & LDF_COLLIDE);
1154 if (sa_low_hit(sai)) {
1156 atomic_inc(&sbi->ll_sa_wrong);
1157 CDEBUG(D_READA, "Statahead for dir "DFID" hit "
1158 "ratio too low: hit/miss "LPU64"/"LPU64
1159 ", sent/replied "LPU64"/"LPU64", stopping "
1160 "statahead thread: pid %d\n",
1161 PFID(&lli->lli_fid), sai->sai_hit,
1162 sai->sai_miss, sai->sai_sent,
1163 sai->sai_replied, current_pid());
1167 ll_dir_chain_fini(&chain);
1168 ll_finish_md_op_data(op_data);
1171 spin_lock(&lli->lli_sa_lock);
1172 thread_set_flags(sa_thread, SVC_STOPPING);
1173 lli->lli_sa_enabled = 0;
1174 spin_unlock(&lli->lli_sa_lock);
1177 /* statahead is finished, but statahead entries need to be cached, wait
1178 * for file release to stop me. */
1179 while (thread_is_running(sa_thread)) {
1180 l_wait_event(sa_thread->t_ctl_waitq,
1181 sa_has_callback(sai) ||
1182 !thread_is_running(sa_thread),
1185 sa_handle_callback(sai);
1190 if (sai->sai_agl_valid) {
1191 spin_lock(&lli->lli_agl_lock);
1192 thread_set_flags(agl_thread, SVC_STOPPING);
1193 spin_unlock(&lli->lli_agl_lock);
1194 wake_up(&agl_thread->t_ctl_waitq);
1196 CDEBUG(D_READA, "stop agl thread: sai %p pid %u\n",
1197 sai, (unsigned int)agl_thread->t_pid);
1198 l_wait_event(agl_thread->t_ctl_waitq,
1199 thread_is_stopped(agl_thread),
1202 /* Set agl_thread flags anyway. */
1203 thread_set_flags(agl_thread, SVC_STOPPED);
1206 /* wait for inflight statahead RPCs to finish, and then we can free sai
1207 * safely because statahead RPC will access sai data */
1208 while (sai->sai_sent != sai->sai_replied) {
1209 /* in case we're not woken up, timeout wait */
1210 lwi = LWI_TIMEOUT(msecs_to_jiffies(MSEC_PER_SEC >> 3),
1212 l_wait_event(sa_thread->t_ctl_waitq,
1213 sai->sai_sent == sai->sai_replied, &lwi);
1216 /* release resources held by statahead RPCs */
1217 sa_handle_callback(sai);
1219 spin_lock(&lli->lli_sa_lock);
1220 thread_set_flags(sa_thread, SVC_STOPPED);
1221 spin_unlock(&lli->lli_sa_lock);
1223 CDEBUG(D_READA, "statahead thread stopped: sai %p, parent %.*s\n",
1224 sai, parent->d_name.len, parent->d_name.name);
1226 wake_up(&sai->sai_waitq);
1227 wake_up(&sa_thread->t_ctl_waitq);
1233 /* authorize opened dir handle @key to statahead */
1234 void ll_authorize_statahead(struct inode *dir, void *key)
1236 struct ll_inode_info *lli = ll_i2info(dir);
1238 spin_lock(&lli->lli_sa_lock);
1239 if (lli->lli_opendir_key == NULL && lli->lli_sai == NULL) {
1241 * if lli_sai is not NULL, it means previous statahead is not
1242 * finished yet, we'd better not start a new statahead for now.
1244 LASSERT(lli->lli_opendir_pid == 0);
1245 lli->lli_opendir_key = key;
1246 lli->lli_opendir_pid = current_pid();
1247 lli->lli_sa_enabled = 1;
1249 spin_unlock(&lli->lli_sa_lock);
1253 * deauthorize opened dir handle @key to statahead, and notify statahead thread
1254 * to quit if it's running.
1256 void ll_deauthorize_statahead(struct inode *dir, void *key)
1258 struct ll_inode_info *lli = ll_i2info(dir);
1259 struct ll_statahead_info *sai;
1261 LASSERT(lli->lli_opendir_key == key);
1262 LASSERT(lli->lli_opendir_pid != 0);
1264 CDEBUG(D_READA, "deauthorize statahead for "DFID"\n",
1265 PFID(&lli->lli_fid));
1267 spin_lock(&lli->lli_sa_lock);
1268 lli->lli_opendir_key = NULL;
1269 lli->lli_opendir_pid = 0;
1270 lli->lli_sa_enabled = 0;
1272 if (sai != NULL && thread_is_running(&sai->sai_thread)) {
1274 * statahead thread may not quit yet because it needs to cache
1275 * entries, now it's time to tell it to quit.
1277 thread_set_flags(&sai->sai_thread, SVC_STOPPING);
1278 wake_up(&sai->sai_thread.t_ctl_waitq);
1280 spin_unlock(&lli->lli_sa_lock);
1285 * not first dirent, or is "."
1287 LS_NOT_FIRST_DE = 0,
1289 * the first non-hidden dirent
1293 * the first hidden dirent, that is "."
1298 /* file is first dirent under @dir */
1299 static int is_first_dirent(struct inode *dir, struct dentry *dentry)
1301 struct ll_dir_chain chain;
1302 struct qstr *target = &dentry->d_name;
1303 struct md_op_data *op_data;
1305 struct page *page = NULL;
1306 int rc = LS_NOT_FIRST_DE;
1310 op_data = ll_prep_md_op_data(NULL, dir, dir, NULL, 0, 0,
1311 LUSTRE_OPC_ANY, dir);
1312 if (IS_ERR(op_data))
1313 RETURN(PTR_ERR(op_data));
1315 *FIXME choose the start offset of the readdir
1317 op_data->op_max_pages = ll_i2sbi(dir)->ll_md_brw_pages;
1319 ll_dir_chain_init(&chain);
1320 page = ll_get_dir_page(dir, op_data, 0, &chain);
1323 struct lu_dirpage *dp;
1324 struct lu_dirent *ent;
1327 struct ll_inode_info *lli = ll_i2info(dir);
1330 CERROR("%s: reading dir "DFID" at "LPU64
1331 "opendir_pid = %u : rc = %d\n",
1332 ll_get_fsname(dir->i_sb, NULL, 0),
1333 PFID(ll_inode2fid(dir)), pos,
1334 lli->lli_opendir_pid, rc);
1338 dp = page_address(page);
1339 for (ent = lu_dirent_start(dp); ent != NULL;
1340 ent = lu_dirent_next(ent)) {
1345 hash = le64_to_cpu(ent->lde_hash);
1346 /* The ll_get_dir_page() can return any page containing
1347 * the given hash which may be not the start hash. */
1348 if (unlikely(hash < pos))
1351 namelen = le16_to_cpu(ent->lde_namelen);
1352 if (unlikely(namelen == 0))
1354 * skip dummy record.
1358 name = ent->lde_name;
1359 if (name[0] == '.') {
1365 else if (name[1] == '.' && namelen == 2)
1376 if (dot_de && target->name[0] != '.') {
1377 CDEBUG(D_READA, "%.*s skip hidden file %.*s\n",
1378 target->len, target->name,
1383 if (target->len != namelen ||
1384 memcmp(target->name, name, namelen) != 0)
1385 rc = LS_NOT_FIRST_DE;
1389 rc = LS_FIRST_DOT_DE;
1391 ll_release_page(dir, page, false);
1394 pos = le64_to_cpu(dp->ldp_hash_end);
1395 if (pos == MDS_DIR_END_OFF) {
1397 * End of directory reached.
1399 ll_release_page(dir, page, false);
1403 * chain is exhausted
1404 * Normal case: continue to the next page.
1406 ll_release_page(dir, page, le32_to_cpu(dp->ldp_flags) &
1408 page = ll_get_dir_page(dir, op_data, pos, &chain);
1413 ll_dir_chain_fini(&chain);
1414 ll_finish_md_op_data(op_data);
1419 * revalidate @dentryp from statahead cache
1421 * \param[in] dir parent directory
1422 * \param[in] sai sai structure
1423 * \param[out] dentryp pointer to dentry which will be revalidated
1424 * \param[in] unplug unplug statahead window only (normally for negative
1426 * \retval 1 on success, dentry is saved in @dentryp
1427 * \retval 0 if revalidation failed (no proper lock on client)
1428 * \retval negative number upon error
1430 static int revalidate_statahead_dentry(struct inode *dir,
1431 struct ll_statahead_info *sai,
1432 struct dentry **dentryp,
1435 struct sa_entry *entry = NULL;
1436 struct l_wait_info lwi = { 0 };
1437 struct ll_dentry_data *ldd;
1438 struct ll_inode_info *lli;
1442 if ((*dentryp)->d_name.name[0] == '.') {
1443 if (sai->sai_ls_all ||
1444 sai->sai_miss_hidden >= sai->sai_skip_hidden) {
1446 * Hidden dentry is the first one, or statahead
1447 * thread does not skip so many hidden dentries
1448 * before "sai_ls_all" enabled as below.
1451 if (!sai->sai_ls_all)
1453 * It maybe because hidden dentry is not
1454 * the first one, "sai_ls_all" was not
1455 * set, then "ls -al" missed. Enable
1456 * "sai_ls_all" for such case.
1458 sai->sai_ls_all = 1;
1461 * Such "getattr" has been skipped before
1462 * "sai_ls_all" enabled as above.
1464 sai->sai_miss_hidden++;
1472 entry = sa_get(sai, &(*dentryp)->d_name);
1474 GOTO(out, rc = -EAGAIN);
1476 /* if statahead is busy in readdir, help it do post-work */
1477 if (!sa_ready(entry) && sai->sai_in_readpage)
1478 sa_handle_callback(sai);
1480 if (!sa_ready(entry)) {
1481 sai->sai_index_wait = entry->se_index;
1482 lwi = LWI_TIMEOUT_INTR(cfs_time_seconds(30), NULL,
1483 LWI_ON_SIGNAL_NOOP, NULL);
1484 rc = l_wait_event(sai->sai_waitq,
1486 thread_is_stopped(&sai->sai_thread),
1490 * entry may not be ready, so it may be used by inflight
1491 * statahead RPC, don't free it.
1494 GOTO(out, rc = -EAGAIN);
1498 if (entry->se_state == SA_ENTRY_SUCC && entry->se_inode != NULL) {
1499 struct inode *inode = entry->se_inode;
1500 struct lookup_intent it = { .it_op = IT_GETATTR,
1501 .d.lustre.it_lock_handle =
1505 rc = md_revalidate_lock(ll_i2mdexp(dir), &it,
1506 ll_inode2fid(inode), &bits);
1508 if ((*dentryp)->d_inode == NULL) {
1509 struct dentry *alias;
1511 alias = ll_splice_alias(inode, *dentryp);
1513 GOTO(out, rc = PTR_ERR(alias));
1515 /* statahead prepared this inode, transfer inode
1516 * refcount from sa_entry to dentry */
1517 entry->se_inode = NULL;
1518 } else if ((*dentryp)->d_inode != inode) {
1519 /* revalidate, but inode is recreated */
1521 "%s: stale dentry %.*s inode "
1522 DFID", statahead inode "DFID
1524 ll_get_fsname((*dentryp)->d_inode->i_sb,
1526 (*dentryp)->d_name.len,
1527 (*dentryp)->d_name.name,
1528 PFID(ll_inode2fid((*dentryp)->d_inode)),
1529 PFID(ll_inode2fid(inode)));
1530 GOTO(out, rc = -ESTALE);
1533 if ((bits & MDS_INODELOCK_LOOKUP) &&
1534 d_lustre_invalid(*dentryp))
1535 d_lustre_revalidate(*dentryp);
1536 ll_intent_release(&it);
1541 * statahead cached sa_entry can be used only once, and will be killed
1542 * right after use, so if lookup/revalidate accessed statahead cache,
1543 * set dentry ldd_sa_generation to parent lli_sa_generation, later if we
1544 * stat this file again, we know we've done statahead before, see
1545 * dentry_may_statahead().
1547 ldd = ll_d2d(*dentryp);
1548 lli = ll_i2info(dir);
1549 /* ldd can be NULL if llite lookup failed. */
1551 ldd->lld_sa_generation = lli->lli_sa_generation;
1558 * start statahead thread
1560 * \param[in] dir parent directory
1561 * \param[in] dentry dentry that triggers statahead, normally the first
1563 * \retval -EAGAIN on success, because when this function is
1564 * called, it's already in lookup call, so client should
1565 * do it itself instead of waiting for statahead thread
1566 * to do it asynchronously.
1567 * \retval negative number upon error
1569 static int start_statahead_thread(struct inode *dir, struct dentry *dentry)
1571 struct ll_inode_info *lli = ll_i2info(dir);
1572 struct ll_statahead_info *sai = NULL;
1573 struct dentry *parent = dentry->d_parent;
1574 struct ptlrpc_thread *thread;
1575 struct l_wait_info lwi = { 0 };
1576 struct task_struct *task;
1580 /* I am the "lli_opendir_pid" owner, only me can set "lli_sai". */
1581 rc = is_first_dirent(dir, dentry);
1582 if (rc == LS_NOT_FIRST_DE)
1583 /* It is not "ls -{a}l" operation, no need statahead for it. */
1584 GOTO(out, rc = -EFAULT);
1586 sai = ll_sai_alloc(parent);
1588 GOTO(out, rc = -ENOMEM);
1590 sai->sai_ls_all = (rc == LS_FIRST_DOT_DE);
1592 /* if current lli_opendir_key was deauthorized, or dir re-opened by
1593 * another process, don't start statahead, otherwise the newly spawned
1594 * statahead thread won't be notified to quit. */
1595 spin_lock(&lli->lli_sa_lock);
1596 if (unlikely(lli->lli_sai != NULL ||
1597 lli->lli_opendir_key == NULL ||
1598 lli->lli_opendir_pid != current->pid)) {
1599 spin_unlock(&lli->lli_sa_lock);
1600 GOTO(out, rc = -EPERM);
1603 spin_unlock(&lli->lli_sa_lock);
1605 atomic_inc(&ll_i2sbi(parent->d_inode)->ll_sa_running);
1607 CDEBUG(D_READA, "start statahead thread: [pid %d] [parent %.*s]\n",
1608 current_pid(), parent->d_name.len, parent->d_name.name);
1610 task = kthread_run(ll_statahead_thread, parent, "ll_sa_%u",
1611 lli->lli_opendir_pid);
1612 thread = &sai->sai_thread;
1615 CERROR("can't start ll_sa thread, rc: %d\n", rc);
1619 l_wait_event(thread->t_ctl_waitq,
1620 thread_is_running(thread) || thread_is_stopped(thread),
1625 * We don't stat-ahead for the first dirent since we are already in
1631 /* once we start statahead thread failed, disable statahead so that
1632 * subsequent stat won't waste time to try it. */
1633 spin_lock(&lli->lli_sa_lock);
1634 lli->lli_sa_enabled = 0;
1635 lli->lli_sai = NULL;
1636 spin_unlock(&lli->lli_sa_lock);
1645 * statahead entry function, this is called when client getattr on a file, it
1646 * will start statahead thread if this is the first dir entry, else revalidate
1647 * dentry from statahead cache.
1649 * \param[in] dir parent directory
1650 * \param[out] dentryp dentry to getattr
1651 * \param[in] unplug unplug statahead window only (normally for negative
1653 * \retval 1 on success
1654 * \retval 0 revalidation from statahead cache failed, caller needs
1655 * to getattr from server directly
1656 * \retval negative number on error, caller often ignores this and
1657 * then getattr from server
1659 int ll_statahead(struct inode *dir, struct dentry **dentryp, bool unplug)
1661 struct ll_statahead_info *sai;
1663 sai = ll_sai_get(dir);
1667 rc = revalidate_statahead_dentry(dir, sai, dentryp, unplug);
1668 CDEBUG(D_READA, "revalidate statahead %.*s: %d.\n",
1669 (*dentryp)->d_name.len, (*dentryp)->d_name.name, rc);
1673 return start_statahead_thread(dir, *dentryp);