lustre/llite/statahead.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   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.
   9  *
  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).
  15  *
  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.gnu.org/licenses/gpl-2.0.html
  19  *
  20  * GPL HEADER END
  21  */
  22 /*
  23  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Use is subject to license terms.
  25  *
  26  * Copyright (c) 2011, 2017, Intel Corporation.
  27  */
  28 /*
  29  * This file is part of Lustre, http://www.lustre.org/
  30  * Lustre is a trademark of Sun Microsystems, Inc.
  31  */
  32
  33 #include <linux/fs.h>
  34 #include <linux/sched.h>
  35 #include <linux/kthread.h>
  36 #include <linux/mm.h>
  37 #include <linux/highmem.h>
  38 #include <linux/pagemap.h>
  39
  40 #define DEBUG_SUBSYSTEM S_LLITE
  41
  42 #include <obd_support.h>
  43 #include <lustre_dlm.h>
  44 #include "llite_internal.h"
  45
  46 #define SA_OMITTED_ENTRY_MAX 8ULL
  47
  48 typedef enum {
  49         /** negative values are for error cases */
  50         SA_ENTRY_INIT = 0,      /** init entry */
  51         SA_ENTRY_SUCC = 1,      /** stat succeed */
  52         SA_ENTRY_INVA = 2,      /** invalid entry */
  53 } se_state_t;
  54
  55 /* sa_entry is not refcounted: statahead thread allocates it and do async stat,
  56  * and in async stat callback ll_statahead_interpret() will add it into
  57  * sai_interim_entries, later statahead thread will call sa_handle_callback() to
  58  * instantiate entry and move it into sai_entries, and then only scanner process
  59  * can access and free it. */
  60 struct sa_entry {
  61         /* link into sai_interim_entries or sai_entries */
  62         struct list_head        se_list;
  63         /* link into sai hash table locally */
  64         struct list_head        se_hash;
  65         /* entry index in the sai */
  66         __u64                   se_index;
  67         /* low layer ldlm lock handle */
  68         __u64                   se_handle;
  69         /* entry status */
  70         se_state_t              se_state;
  71         /* entry size, contains name */
  72         int                     se_size;
  73         /* pointer to async getattr enqueue info */
  74         struct md_enqueue_info *se_minfo;
  75         /* pointer to the async getattr request */
  76         struct ptlrpc_request  *se_req;
  77         /* pointer to the target inode */
  78         struct inode           *se_inode;
  79         /* entry name */
  80         struct qstr             se_qstr;
  81         /* entry fid */
  82         struct lu_fid           se_fid;
  83 };
  84
  85 static unsigned int sai_generation = 0;
  86 static DEFINE_SPINLOCK(sai_generation_lock);
  87
  88 static inline int sa_unhashed(struct sa_entry *entry)
  89 {
  90         return list_empty(&entry->se_hash);
  91 }
  92
  93 /* sa_entry is ready to use */
  94 static inline int sa_ready(struct sa_entry *entry)
  95 {
  96         smp_rmb();
  97         return (entry->se_state != SA_ENTRY_INIT);
  98 }
  99
 100 /* hash value to put in sai_cache */
 101 static inline int sa_hash(int val)
 102 {
 103         return val & LL_SA_CACHE_MASK;
 104 }
 105
 106 /* hash entry into sai_cache */
 107 static inline void
 108 sa_rehash(struct ll_statahead_info *sai, struct sa_entry *entry)
 109 {
 110         int i = sa_hash(entry->se_qstr.hash);
 111
 112         spin_lock(&sai->sai_cache_lock[i]);
 113         list_add_tail(&entry->se_hash, &sai->sai_cache[i]);
 114         spin_unlock(&sai->sai_cache_lock[i]);
 115 }
 116
 117 /* unhash entry from sai_cache */
 118 static inline void
 119 sa_unhash(struct ll_statahead_info *sai, struct sa_entry *entry)
 120 {
 121         int i = sa_hash(entry->se_qstr.hash);
 122
 123         spin_lock(&sai->sai_cache_lock[i]);
 124         list_del_init(&entry->se_hash);
 125         spin_unlock(&sai->sai_cache_lock[i]);
 126 }
 127
 128 static inline int agl_should_run(struct ll_statahead_info *sai,
 129                                  struct inode *inode)
 130 {
 131         return (inode != NULL && S_ISREG(inode->i_mode) && sai->sai_agl_valid);
 132 }
 133
 134 static inline struct ll_inode_info *
 135 agl_first_entry(struct ll_statahead_info *sai)
 136 {
 137         return list_entry(sai->sai_agls.next, struct ll_inode_info,
 138                           lli_agl_list);
 139 }
 140
 141 /* statahead window is full */
 142 static inline int sa_sent_full(struct ll_statahead_info *sai)
 143 {
 144         return atomic_read(&sai->sai_cache_count) >= sai->sai_max;
 145 }
 146
 147 /* got async stat replies */
 148 static inline int sa_has_callback(struct ll_statahead_info *sai)
 149 {
 150         return !list_empty(&sai->sai_interim_entries);
 151 }
 152
 153 static inline int agl_list_empty(struct ll_statahead_info *sai)
 154 {
 155         return list_empty(&sai->sai_agls);
 156 }
 157
 158 /**
 159  * (1) hit ratio less than 80%
 160  * or
 161  * (2) consecutive miss more than 8
 162  * then means low hit.
 163  */
 164 static inline int sa_low_hit(struct ll_statahead_info *sai)
 165 {
 166         return ((sai->sai_hit > 7 && sai->sai_hit < 4 * sai->sai_miss) ||
 167                 (sai->sai_consecutive_miss > 8));
 168 }
 169
 170 /*
 171  * if the given index is behind of statahead window more than
 172  * SA_OMITTED_ENTRY_MAX, then it is old.
 173  */
 174 static inline int is_omitted_entry(struct ll_statahead_info *sai, __u64 index)
 175 {
 176         return ((__u64)sai->sai_max + index + SA_OMITTED_ENTRY_MAX <
 177                  sai->sai_index);
 178 }
 179
 180 /* allocate sa_entry and hash it to allow scanner process to find it */
 181 static struct sa_entry *
 182 sa_alloc(struct dentry *parent, struct ll_statahead_info *sai, __u64 index,
 183          const char *name, int len, const struct lu_fid *fid)
 184 {
 185         struct ll_inode_info *lli;
 186         struct sa_entry *entry;
 187         int entry_size;
 188         char *dname;
 189         ENTRY;
 190
 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));
 195
 196         CDEBUG(D_READA, "alloc sa entry %.*s(%p) index %llu\n",
 197                len, name, entry, index);
 198
 199         entry->se_index = index;
 200
 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);
 205         dname[len] = 0;
 206         entry->se_qstr.hash = ll_full_name_hash(parent, name, len);
 207         entry->se_qstr.len = len;
 208         entry->se_qstr.name = dname;
 209         entry->se_fid = *fid;
 210
 211         lli = ll_i2info(sai->sai_dentry->d_inode);
 212
 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);
 217
 218         atomic_inc(&sai->sai_cache_count);
 219
 220         RETURN(entry);
 221 }
 222
 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)
 225 {
 226         CDEBUG(D_READA, "free sa entry %.*s(%p) index %llu\n",
 227                entry->se_qstr.len, entry->se_qstr.name, entry,
 228                entry->se_index);
 229
 230         LASSERT(list_empty(&entry->se_list));
 231         LASSERT(sa_unhashed(entry));
 232
 233         OBD_FREE(entry, entry->se_size);
 234         atomic_dec(&sai->sai_cache_count);
 235 }
 236
 237 /*
 238  * find sa_entry by name, used by directory scanner, lock is not needed because
 239  * only scanner can remove the entry from cache.
 240  */
 241 static struct sa_entry *
 242 sa_get(struct ll_statahead_info *sai, const struct qstr *qstr)
 243 {
 244         struct sa_entry *entry;
 245         int i = sa_hash(qstr->hash);
 246
 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)
 251                         return entry;
 252         }
 253         return NULL;
 254 }
 255
 256 /* unhash and unlink sa_entry, and then free it */
 257 static inline void
 258 sa_kill(struct ll_statahead_info *sai, struct sa_entry *entry)
 259 {
 260         struct ll_inode_info *lli = ll_i2info(sai->sai_dentry->d_inode);
 261
 262         LASSERT(!sa_unhashed(entry));
 263         LASSERT(!list_empty(&entry->se_list));
 264         LASSERT(sa_ready(entry));
 265
 266         sa_unhash(sai, entry);
 267
 268         spin_lock(&lli->lli_sa_lock);
 269         list_del_init(&entry->se_list);
 270         spin_unlock(&lli->lli_sa_lock);
 271
 272         if (entry->se_inode != NULL)
 273                 iput(entry->se_inode);
 274
 275         sa_free(sai, entry);
 276 }
 277
 278 /* called by scanner after use, sa_entry will be killed */
 279 static void
 280 sa_put(struct ll_statahead_info *sai, struct sa_entry *entry)
 281 {
 282         struct sa_entry *tmp, *next;
 283
 284         if (entry != NULL && entry->se_state == SA_ENTRY_SUCC) {
 285                 struct ll_sb_info *sbi = ll_i2sbi(sai->sai_dentry->d_inode);
 286
 287                 sai->sai_hit++;
 288                 sai->sai_consecutive_miss = 0;
 289                 sai->sai_max = min(2 * sai->sai_max, sbi->ll_sa_max);
 290         } else {
 291                 sai->sai_miss++;
 292                 sai->sai_consecutive_miss++;
 293         }
 294
 295         if (entry != NULL)
 296                 sa_kill(sai, entry);
 297
 298         /* kill old completed entries, only scanner process does this, no need
 299          * to lock */
 300         list_for_each_entry_safe(tmp, next, &sai->sai_entries, se_list) {
 301                 if (!is_omitted_entry(sai, tmp->se_index))
 302                         break;
 303                 sa_kill(sai, tmp);
 304         }
 305
 306         wake_up(&sai->sai_thread.t_ctl_waitq);
 307 }
 308
 309 /* update state and sort add entry to sai_entries by index, return true if
 310  * scanner is waiting on this entry. */
 311 static bool
 312 __sa_make_ready(struct ll_statahead_info *sai, struct sa_entry *entry, int ret)
 313 {
 314         struct sa_entry *se;
 315         struct list_head *pos = &sai->sai_entries;
 316         __u64 index = entry->se_index;
 317
 318         LASSERT(!sa_ready(entry));
 319         LASSERT(list_empty(&entry->se_list));
 320
 321         list_for_each_entry_reverse(se, &sai->sai_entries, se_list) {
 322                 if (se->se_index < entry->se_index) {
 323                         pos = &se->se_list;
 324                         break;
 325                 }
 326         }
 327         list_add(&entry->se_list, pos);
 328         entry->se_state = ret < 0 ? SA_ENTRY_INVA : SA_ENTRY_SUCC;
 329
 330         return (index == sai->sai_index_wait);
 331 }
 332
 333 /*
 334  * release resources used in async stat RPC, update entry state and wakeup if
 335  * scanner process it waiting on this entry.
 336  */
 337 static void
 338 sa_make_ready(struct ll_statahead_info *sai, struct sa_entry *entry, int ret)
 339 {
 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;
 343         bool wakeup;
 344
 345         /* release resources used in RPC */
 346         if (minfo) {
 347                 entry->se_minfo = NULL;
 348                 ll_intent_release(&minfo->mi_it);
 349                 iput(minfo->mi_dir);
 350                 OBD_FREE_PTR(minfo);
 351         }
 352
 353         if (req) {
 354                 entry->se_req = NULL;
 355                 ptlrpc_req_finished(req);
 356         }
 357
 358         spin_lock(&lli->lli_sa_lock);
 359         wakeup = __sa_make_ready(sai, entry, ret);
 360         spin_unlock(&lli->lli_sa_lock);
 361
 362         if (wakeup)
 363                 wake_up(&sai->sai_waitq);
 364 }
 365
 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)
 369 {
 370         struct ll_inode_info *child  = ll_i2info(inode);
 371         struct ll_inode_info *parent = ll_i2info(sai->sai_dentry->d_inode);
 372         int                   added  = 0;
 373
 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);
 378
 379                 LASSERT(list_empty(&child->lli_agl_list));
 380
 381                 igrab(inode);
 382                 spin_lock(&parent->lli_agl_lock);
 383                 if (agl_list_empty(sai))
 384                         added = 1;
 385                 list_add_tail(&child->lli_agl_list, &sai->sai_agls);
 386                 spin_unlock(&parent->lli_agl_lock);
 387         } else {
 388                 spin_unlock(&child->lli_agl_lock);
 389         }
 390
 391         if (added > 0)
 392                 wake_up(&sai->sai_agl_thread.t_ctl_waitq);
 393 }
 394
 395 /* allocate sai */
 396 static struct ll_statahead_info *ll_sai_alloc(struct dentry *dentry)
 397 {
 398         struct ll_statahead_info *sai;
 399         struct ll_inode_info *lli = ll_i2info(dentry->d_inode);
 400         int i;
 401         ENTRY;
 402
 403         OBD_ALLOC_PTR(sai);
 404         if (!sai)
 405                 RETURN(NULL);
 406
 407         sai->sai_dentry = dget(dentry);
 408         atomic_set(&sai->sai_refcount, 1);
 409         sai->sai_max = LL_SA_RPC_MIN;
 410         sai->sai_index = 1;
 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);
 414
 415         INIT_LIST_HEAD(&sai->sai_interim_entries);
 416         INIT_LIST_HEAD(&sai->sai_entries);
 417         INIT_LIST_HEAD(&sai->sai_agls);
 418
 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]);
 422         }
 423         atomic_set(&sai->sai_cache_count, 0);
 424
 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);
 430
 431         RETURN(sai);
 432 }
 433
 434 /* free sai */
 435 static inline void ll_sai_free(struct ll_statahead_info *sai)
 436 {
 437         LASSERT(sai->sai_dentry != NULL);
 438         dput(sai->sai_dentry);
 439         OBD_FREE_PTR(sai);
 440 }
 441
 442 /*
 443  * take refcount of sai if sai for @dir exists, which means statahead is on for
 444  * this directory.
 445  */
 446 static inline struct ll_statahead_info *ll_sai_get(struct inode *dir)
 447 {
 448         struct ll_inode_info *lli = ll_i2info(dir);
 449         struct ll_statahead_info *sai = NULL;
 450
 451         spin_lock(&lli->lli_sa_lock);
 452         sai = lli->lli_sai;
 453         if (sai != NULL)
 454                 atomic_inc(&sai->sai_refcount);
 455         spin_unlock(&lli->lli_sa_lock);
 456
 457         return sai;
 458 }
 459
 460 /*
 461  * put sai refcount after use, if refcount reaches zero, free sai and sa_entries
 462  * attached to it.
 463  */
 464 static void ll_sai_put(struct ll_statahead_info *sai)
 465 {
 466         struct ll_inode_info *lli = ll_i2info(sai->sai_dentry->d_inode);
 467
 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);
 471
 472                 lli->lli_sai = NULL;
 473                 spin_unlock(&lli->lli_sa_lock);
 474
 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));
 479
 480                 list_for_each_entry_safe(entry, next, &sai->sai_entries,
 481                                          se_list)
 482                         sa_kill(sai, entry);
 483
 484                 LASSERT(atomic_read(&sai->sai_cache_count) == 0);
 485                 LASSERT(agl_list_empty(sai));
 486
 487                 ll_sai_free(sai);
 488                 atomic_dec(&sbi->ll_sa_running);
 489         }
 490 }
 491
 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)
 494 {
 495         struct ll_inode_info *lli = ll_i2info(inode);
 496         u64 index = lli->lli_agl_index;
 497         ktime_t expire;
 498         int rc;
 499
 500         ENTRY;
 501         LASSERT(list_empty(&lli->lli_agl_list));
 502
 503         /* AGL maybe fall behind statahead with one entry */
 504         if (is_omitted_entry(sai, index + 1)) {
 505                 lli->lli_agl_index = 0;
 506                 iput(inode);
 507                 RETURN_EXIT;
 508         }
 509
 510         /* In case of restore, the MDT has the right size and has already
 511          * sent it back without granting the layout lock, inode is up-to-date.
 512          * Then AGL (async glimpse lock) is useless.
 513          * Also to glimpse we need the layout, in case of a runninh restore
 514          * the MDT holds the layout lock so the glimpse will block up to the
 515          * end of restore (statahead/agl will block) */
 516         if (ll_file_test_flag(lli, LLIF_FILE_RESTORING)) {
 517                 lli->lli_agl_index = 0;
 518                 iput(inode);
 519                 RETURN_EXIT;
 520         }
 521
 522         /* Someone is in glimpse (sync or async), do nothing. */
 523         rc = down_write_trylock(&lli->lli_glimpse_sem);
 524         if (rc == 0) {
 525                 lli->lli_agl_index = 0;
 526                 iput(inode);
 527                 RETURN_EXIT;
 528         }
 529
 530         /*
 531          * Someone triggered glimpse within 1 sec before.
 532          * 1) The former glimpse succeeded with glimpse lock granted by OST, and
 533          *    if the lock is still cached on client, AGL needs to do nothing. If
 534          *    it is cancelled by other client, AGL maybe cannot obtaion new lock
 535          *    for no glimpse callback triggered by AGL.
 536          * 2) The former glimpse succeeded, but OST did not grant glimpse lock.
 537          *    Under such case, it is quite possible that the OST will not grant
 538          *    glimpse lock for AGL also.
 539          * 3) The former glimpse failed, compared with other two cases, it is
 540          *    relative rare. AGL can ignore such case, and it will not muchly
 541          *    affect the performance.
 542          */
 543         expire = ktime_sub_ns(ktime_get(), NSEC_PER_SEC);
 544         if (ktime_to_ns(lli->lli_glimpse_time) &&
 545             ktime_before(expire, lli->lli_glimpse_time)) {
 546                 up_write(&lli->lli_glimpse_sem);
 547                 lli->lli_agl_index = 0;
 548                 iput(inode);
 549                 RETURN_EXIT;
 550         }
 551
 552         CDEBUG(D_READA, "Handling (init) async glimpse: inode = "
 553                DFID", idx = %llu\n", PFID(&lli->lli_fid), index);
 554
 555         cl_agl(inode);
 556         lli->lli_agl_index = 0;
 557         lli->lli_glimpse_time = ktime_get();
 558         up_write(&lli->lli_glimpse_sem);
 559
 560         CDEBUG(D_READA, "Handled (init) async glimpse: inode= "
 561                DFID", idx = %llu, rc = %d\n",
 562                PFID(&lli->lli_fid), index, rc);
 563
 564         iput(inode);
 565
 566         EXIT;
 567 }
 568
 569 /*
 570  * prepare inode for sa entry, add it into agl list, now sa_entry is ready
 571  * to be used by scanner process.
 572  */
 573 static void sa_instantiate(struct ll_statahead_info *sai,
 574                                  struct sa_entry *entry)
 575 {
 576         struct inode *dir = sai->sai_dentry->d_inode;
 577         struct inode *child;
 578         struct md_enqueue_info *minfo;
 579         struct lookup_intent *it;
 580         struct ptlrpc_request *req;
 581         struct mdt_body *body;
 582         int rc = 0;
 583         ENTRY;
 584
 585         LASSERT(entry->se_handle != 0);
 586
 587         minfo = entry->se_minfo;
 588         it = &minfo->mi_it;
 589         req = entry->se_req;
 590         body = req_capsule_server_get(&req->rq_pill, &RMF_MDT_BODY);
 591         if (body == NULL)
 592                 GOTO(out, rc = -EFAULT);
 593
 594         child = entry->se_inode;
 595         if (child != NULL) {
 596                 /* revalidate; unlinked and re-created with the same name */
 597                 if (unlikely(!lu_fid_eq(&minfo->mi_data.op_fid2,
 598                                         &body->mbo_fid1))) {
 599                         entry->se_inode = NULL;
 600                         iput(child);
 601                         child = NULL;
 602                 }
 603         }
 604
 605         it->it_lock_handle = entry->se_handle;
 606         rc = md_revalidate_lock(ll_i2mdexp(dir), it, ll_inode2fid(dir), NULL);
 607         if (rc != 1)
 608                 GOTO(out, rc = -EAGAIN);
 609
 610         rc = ll_prep_inode(&child, req, dir->i_sb, it);
 611         if (rc)
 612                 GOTO(out, rc);
 613
 614         CDEBUG(D_READA, "%s: setting %.*s"DFID" l_data to inode %p\n",
 615                ll_get_fsname(child->i_sb, NULL, 0),
 616                entry->se_qstr.len, entry->se_qstr.name,
 617                PFID(ll_inode2fid(child)), child);
 618         ll_set_lock_data(ll_i2sbi(dir)->ll_md_exp, child, it, NULL);
 619
 620         entry->se_inode = child;
 621
 622         if (agl_should_run(sai, child))
 623                 ll_agl_add(sai, child, entry->se_index);
 624
 625         EXIT;
 626
 627 out:
 628         /* sa_make_ready() will drop ldlm ibits lock refcount by calling
 629          * ll_intent_drop_lock() in spite of failures. Do not worry about
 630          * calling ll_intent_drop_lock() more than once. */
 631         sa_make_ready(sai, entry, rc);
 632 }
 633
 634 /* once there are async stat replies, instantiate sa_entry from replies */
 635 static void sa_handle_callback(struct ll_statahead_info *sai)
 636 {
 637         struct ll_inode_info *lli;
 638
 639         lli = ll_i2info(sai->sai_dentry->d_inode);
 640
 641         while (sa_has_callback(sai)) {
 642                 struct sa_entry *entry;
 643
 644                 spin_lock(&lli->lli_sa_lock);
 645                 if (unlikely(!sa_has_callback(sai))) {
 646                         spin_unlock(&lli->lli_sa_lock);
 647                         break;
 648                 }
 649                 entry = list_entry(sai->sai_interim_entries.next,
 650                                    struct sa_entry, se_list);
 651                 list_del_init(&entry->se_list);
 652                 spin_unlock(&lli->lli_sa_lock);
 653
 654                 sa_instantiate(sai, entry);
 655         }
 656 }
 657
 658 /*
 659  * callback for async stat RPC, because this is called in ptlrpcd context, we
 660  * only put sa_entry in sai_interim_entries, and wake up statahead thread to
 661  * really prepare inode and instantiate sa_entry later.
 662  */
 663 static int ll_statahead_interpret(struct ptlrpc_request *req,
 664                                   struct md_enqueue_info *minfo, int rc)
 665 {
 666         struct lookup_intent *it = &minfo->mi_it;
 667         struct inode *dir = minfo->mi_dir;
 668         struct ll_inode_info *lli = ll_i2info(dir);
 669         struct ll_statahead_info *sai = lli->lli_sai;
 670         struct sa_entry *entry = (struct sa_entry *)minfo->mi_cbdata;
 671         __u64 handle = 0;
 672         wait_queue_head_t *waitq = NULL;
 673         ENTRY;
 674
 675         if (it_disposition(it, DISP_LOOKUP_NEG))
 676                 rc = -ENOENT;
 677
 678         /* because statahead thread will wait for all inflight RPC to finish,
 679          * sai should be always valid, no need to refcount */
 680         LASSERT(sai != NULL);
 681         LASSERT(!thread_is_stopped(&sai->sai_thread));
 682         LASSERT(entry != NULL);
 683
 684         CDEBUG(D_READA, "sa_entry %.*s rc %d\n",
 685                entry->se_qstr.len, entry->se_qstr.name, rc);
 686
 687         if (rc != 0) {
 688                 ll_intent_release(it);
 689                 iput(dir);
 690                 OBD_FREE_PTR(minfo);
 691         } else {
 692                 /* release ibits lock ASAP to avoid deadlock when statahead
 693                  * thread enqueues lock on parent in readdir and another
 694                  * process enqueues lock on child with parent lock held, eg.
 695                  * unlink. */
 696                 handle = it->it_lock_handle;
 697                 ll_intent_drop_lock(it);
 698         }
 699
 700         spin_lock(&lli->lli_sa_lock);
 701         if (rc != 0) {
 702                 if (__sa_make_ready(sai, entry, rc))
 703                         waitq = &sai->sai_waitq;
 704         } else {
 705                 entry->se_minfo = minfo;
 706                 entry->se_req = ptlrpc_request_addref(req);
 707                 /* Release the async ibits lock ASAP to avoid deadlock
 708                  * when statahead thread tries to enqueue lock on parent
 709                  * for readpage and other tries to enqueue lock on child
 710                  * with parent's lock held, for example: unlink. */
 711                 entry->se_handle = handle;
 712                 if (!sa_has_callback(sai))
 713                         waitq = &sai->sai_thread.t_ctl_waitq;
 714
 715                 list_add_tail(&entry->se_list, &sai->sai_interim_entries);
 716         }
 717         sai->sai_replied++;
 718
 719         smp_mb();
 720         if (waitq != NULL)
 721                 wake_up(waitq);
 722         spin_unlock(&lli->lli_sa_lock);
 723
 724         RETURN(rc);
 725 }
 726
 727 /* finish async stat RPC arguments */
 728 static void sa_fini_data(struct md_enqueue_info *minfo)
 729 {
 730         iput(minfo->mi_dir);
 731         OBD_FREE_PTR(minfo);
 732 }
 733
 734 /*
 735  * prepare arguments for async stat RPC.
 736  */
 737 static struct md_enqueue_info *
 738 sa_prep_data(struct inode *dir, struct inode *child, struct sa_entry *entry)
 739 {
 740         struct md_enqueue_info   *minfo;
 741         struct ldlm_enqueue_info *einfo;
 742         struct md_op_data        *op_data;
 743
 744         OBD_ALLOC_PTR(minfo);
 745         if (minfo == NULL)
 746                 return ERR_PTR(-ENOMEM);
 747
 748         op_data = ll_prep_md_op_data(&minfo->mi_data, dir, child,
 749                                      entry->se_qstr.name, entry->se_qstr.len, 0,
 750                                      LUSTRE_OPC_ANY, NULL);
 751         if (IS_ERR(op_data)) {
 752                 OBD_FREE_PTR(minfo);
 753                 return (struct md_enqueue_info *)op_data;
 754         }
 755
 756         if (child == NULL)
 757                 op_data->op_fid2 = entry->se_fid;
 758
 759         minfo->mi_it.it_op = IT_GETATTR;
 760         minfo->mi_dir = igrab(dir);
 761         minfo->mi_cb = ll_statahead_interpret;
 762         minfo->mi_cbdata = entry;
 763
 764         einfo = &minfo->mi_einfo;
 765         einfo->ei_type   = LDLM_IBITS;
 766         einfo->ei_mode   = it_to_lock_mode(&minfo->mi_it);
 767         einfo->ei_cb_bl  = ll_md_blocking_ast;
 768         einfo->ei_cb_cp  = ldlm_completion_ast;
 769         einfo->ei_cb_gl  = NULL;
 770         einfo->ei_cbdata = NULL;
 771
 772         return minfo;
 773 }
 774
 775 /* async stat for file not found in dcache */
 776 static int sa_lookup(struct inode *dir, struct sa_entry *entry)
 777 {
 778         struct md_enqueue_info   *minfo;
 779         int                       rc;
 780         ENTRY;
 781
 782         minfo = sa_prep_data(dir, NULL, entry);
 783         if (IS_ERR(minfo))
 784                 RETURN(PTR_ERR(minfo));
 785
 786         rc = md_intent_getattr_async(ll_i2mdexp(dir), minfo);
 787         if (rc < 0)
 788                 sa_fini_data(minfo);
 789
 790         RETURN(rc);
 791 }
 792
 793 /**
 794  * async stat for file found in dcache, similar to .revalidate
 795  *
 796  * \retval      1 dentry valid, no RPC sent
 797  * \retval      0 dentry invalid, will send async stat RPC
 798  * \retval      negative number upon error
 799  */
 800 static int sa_revalidate(struct inode *dir, struct sa_entry *entry,
 801                          struct dentry *dentry)
 802 {
 803         struct inode *inode = dentry->d_inode;
 804         struct lookup_intent it = { .it_op = IT_GETATTR,
 805                                     .it_lock_handle = 0 };
 806         struct md_enqueue_info *minfo;
 807         int rc;
 808         ENTRY;
 809
 810         if (unlikely(inode == NULL))
 811                 RETURN(1);
 812
 813         if (d_mountpoint(dentry))
 814                 RETURN(1);
 815
 816         entry->se_inode = igrab(inode);
 817         rc = md_revalidate_lock(ll_i2mdexp(dir), &it, ll_inode2fid(inode),
 818                                 NULL);
 819         if (rc == 1) {
 820                 entry->se_handle = it.it_lock_handle;
 821                 ll_intent_release(&it);
 822                 RETURN(1);
 823         }
 824
 825         minfo = sa_prep_data(dir, inode, entry);
 826         if (IS_ERR(minfo)) {
 827                 entry->se_inode = NULL;
 828                 iput(inode);
 829                 RETURN(PTR_ERR(minfo));
 830         }
 831
 832         rc = md_intent_getattr_async(ll_i2mdexp(dir), minfo);
 833         if (rc < 0) {
 834                 entry->se_inode = NULL;
 835                 iput(inode);
 836                 sa_fini_data(minfo);
 837         }
 838
 839         RETURN(rc);
 840 }
 841
 842 /* async stat for file with @name */
 843 static void sa_statahead(struct dentry *parent, const char *name, int len,
 844                          const struct lu_fid *fid)
 845 {
 846         struct inode *dir = parent->d_inode;
 847         struct ll_inode_info *lli = ll_i2info(dir);
 848         struct ll_statahead_info *sai = lli->lli_sai;
 849         struct dentry *dentry = NULL;
 850         struct sa_entry *entry;
 851         int rc;
 852         ENTRY;
 853
 854         entry = sa_alloc(parent, sai, sai->sai_index, name, len, fid);
 855         if (IS_ERR(entry))
 856                 RETURN_EXIT;
 857
 858         dentry = d_lookup(parent, &entry->se_qstr);
 859         if (!dentry) {
 860                 rc = sa_lookup(dir, entry);
 861         } else {
 862                 rc = sa_revalidate(dir, entry, dentry);
 863                 if (rc == 1 && agl_should_run(sai, dentry->d_inode))
 864                         ll_agl_add(sai, dentry->d_inode, entry->se_index);
 865         }
 866
 867         if (dentry != NULL)
 868                 dput(dentry);
 869
 870         if (rc != 0)
 871                 sa_make_ready(sai, entry, rc);
 872         else
 873                 sai->sai_sent++;
 874
 875         sai->sai_index++;
 876
 877         EXIT;
 878 }
 879
 880 /* async glimpse (agl) thread main function */
 881 static int ll_agl_thread(void *arg)
 882 {
 883         struct dentry *parent = (struct dentry *)arg;
 884         struct inode *dir = parent->d_inode;
 885         struct ll_inode_info *plli = ll_i2info(dir);
 886         struct ll_inode_info *clli;
 887         struct ll_sb_info *sbi = ll_i2sbi(dir);
 888         struct ll_statahead_info *sai;
 889         struct ptlrpc_thread *thread;
 890         struct l_wait_info lwi = { 0 };
 891         ENTRY;
 892
 893
 894         sai = ll_sai_get(dir);
 895         thread = &sai->sai_agl_thread;
 896         thread->t_pid = current_pid();
 897         CDEBUG(D_READA, "agl thread started: sai %p, parent %.*s\n",
 898                sai, parent->d_name.len, parent->d_name.name);
 899
 900         atomic_inc(&sbi->ll_agl_total);
 901         spin_lock(&plli->lli_agl_lock);
 902         sai->sai_agl_valid = 1;
 903         if (thread_is_init(thread))
 904                 /* If someone else has changed the thread state
 905                  * (e.g. already changed to SVC_STOPPING), we can't just
 906                  * blindly overwrite that setting. */
 907                 thread_set_flags(thread, SVC_RUNNING);
 908         spin_unlock(&plli->lli_agl_lock);
 909         wake_up(&thread->t_ctl_waitq);
 910
 911         while (1) {
 912                 l_wait_event(thread->t_ctl_waitq,
 913                              !agl_list_empty(sai) ||
 914                              !thread_is_running(thread),
 915                              &lwi);
 916
 917                 if (!thread_is_running(thread))
 918                         break;
 919
 920                 spin_lock(&plli->lli_agl_lock);
 921                 /* The statahead thread maybe help to process AGL entries,
 922                  * so check whether list empty again. */
 923                 if (!agl_list_empty(sai)) {
 924                         clli = agl_first_entry(sai);
 925                         list_del_init(&clli->lli_agl_list);
 926                         spin_unlock(&plli->lli_agl_lock);
 927                         ll_agl_trigger(&clli->lli_vfs_inode, sai);
 928                         cond_resched();
 929                 } else {
 930                         spin_unlock(&plli->lli_agl_lock);
 931                 }
 932         }
 933
 934         spin_lock(&plli->lli_agl_lock);
 935         sai->sai_agl_valid = 0;
 936         while (!agl_list_empty(sai)) {
 937                 clli = agl_first_entry(sai);
 938                 list_del_init(&clli->lli_agl_list);
 939                 spin_unlock(&plli->lli_agl_lock);
 940                 clli->lli_agl_index = 0;
 941                 iput(&clli->lli_vfs_inode);
 942                 spin_lock(&plli->lli_agl_lock);
 943         }
 944         thread_set_flags(thread, SVC_STOPPED);
 945         spin_unlock(&plli->lli_agl_lock);
 946         wake_up(&thread->t_ctl_waitq);
 947         ll_sai_put(sai);
 948         CDEBUG(D_READA, "agl thread stopped: sai %p, parent %.*s\n",
 949                sai, parent->d_name.len, parent->d_name.name);
 950         RETURN(0);
 951 }
 952
 953 /* start agl thread */
 954 static void ll_start_agl(struct dentry *parent, struct ll_statahead_info *sai)
 955 {
 956         struct ptlrpc_thread *thread = &sai->sai_agl_thread;
 957         struct l_wait_info    lwi    = { 0 };
 958         struct ll_inode_info  *plli;
 959         struct task_struct            *task;
 960         ENTRY;
 961
 962         CDEBUG(D_READA, "start agl thread: sai %p, parent %.*s\n",
 963                sai, parent->d_name.len, parent->d_name.name);
 964
 965         plli = ll_i2info(parent->d_inode);
 966         task = kthread_run(ll_agl_thread, parent,
 967                                "ll_agl_%u", plli->lli_opendir_pid);
 968         if (IS_ERR(task)) {
 969                 CERROR("can't start ll_agl thread, rc: %ld\n", PTR_ERR(task));
 970                 thread_set_flags(thread, SVC_STOPPED);
 971                 RETURN_EXIT;
 972         }
 973
 974         l_wait_event(thread->t_ctl_waitq,
 975                      thread_is_running(thread) || thread_is_stopped(thread),
 976                      &lwi);
 977         EXIT;
 978 }
 979
 980 /* statahead thread main function */
 981 static int ll_statahead_thread(void *arg)
 982 {
 983         struct dentry *parent = (struct dentry *)arg;
 984         struct inode *dir = parent->d_inode;
 985         struct ll_inode_info *lli = ll_i2info(dir);
 986         struct ll_sb_info *sbi = ll_i2sbi(dir);
 987         struct ll_statahead_info *sai;
 988         struct ptlrpc_thread *sa_thread;
 989         struct ptlrpc_thread *agl_thread;
 990         int first = 0;
 991         struct md_op_data *op_data;
 992         struct ll_dir_chain chain;
 993         struct l_wait_info lwi = { 0 };
 994         struct page *page = NULL;
 995         __u64 pos = 0;
 996         int rc = 0;
 997         ENTRY;
 998
 999         sai = ll_sai_get(dir);
1000         sa_thread = &sai->sai_thread;
1001         agl_thread = &sai->sai_agl_thread;
1002         sa_thread->t_pid = current_pid();
1003         CDEBUG(D_READA, "statahead thread starting: sai %p, parent %.*s\n",
1004                sai, parent->d_name.len, parent->d_name.name);
1005
1006         op_data = ll_prep_md_op_data(NULL, dir, dir, NULL, 0, 0,
1007                                      LUSTRE_OPC_ANY, dir);
1008         if (IS_ERR(op_data))
1009                 GOTO(out, rc = PTR_ERR(op_data));
1010
1011         if (sbi->ll_flags & LL_SBI_AGL_ENABLED)
1012                 ll_start_agl(parent, sai);
1013
1014         atomic_inc(&sbi->ll_sa_total);
1015         spin_lock(&lli->lli_sa_lock);
1016         if (thread_is_init(sa_thread))
1017                 /* If someone else has changed the thread state
1018                  * (e.g. already changed to SVC_STOPPING), we can't just
1019                  * blindly overwrite that setting. */
1020                 thread_set_flags(sa_thread, SVC_RUNNING);
1021         spin_unlock(&lli->lli_sa_lock);
1022         wake_up(&sa_thread->t_ctl_waitq);
1023
1024         ll_dir_chain_init(&chain);
1025         while (pos != MDS_DIR_END_OFF && thread_is_running(sa_thread)) {
1026                 struct lu_dirpage *dp;
1027                 struct lu_dirent  *ent;
1028
1029                 sai->sai_in_readpage = 1;
1030                 page = ll_get_dir_page(dir, op_data, pos, &chain);
1031                 sai->sai_in_readpage = 0;
1032                 if (IS_ERR(page)) {
1033                         rc = PTR_ERR(page);
1034                         CDEBUG(D_READA, "error reading dir "DFID" at %llu"
1035                                "/%llu opendir_pid = %u: rc = %d\n",
1036                                PFID(ll_inode2fid(dir)), pos, sai->sai_index,
1037                                lli->lli_opendir_pid, rc);
1038                         break;
1039                 }
1040
1041                 dp = page_address(page);
1042                 for (ent = lu_dirent_start(dp);
1043                      ent != NULL && thread_is_running(sa_thread) &&
1044                      !sa_low_hit(sai);
1045                      ent = lu_dirent_next(ent)) {
1046                         __u64 hash;
1047                         int namelen;
1048                         char *name;
1049                         struct lu_fid fid;
1050
1051                         hash = le64_to_cpu(ent->lde_hash);
1052                         if (unlikely(hash < pos))
1053                                 /*
1054                                  * Skip until we find target hash value.
1055                                  */
1056                                 continue;
1057
1058                         namelen = le16_to_cpu(ent->lde_namelen);
1059                         if (unlikely(namelen == 0))
1060                                 /*
1061                                  * Skip dummy record.
1062                                  */
1063                                 continue;
1064
1065                         name = ent->lde_name;
1066                         if (name[0] == '.') {
1067                                 if (namelen == 1) {
1068                                         /*
1069                                          * skip "."
1070                                          */
1071                                         continue;
1072                                 } else if (name[1] == '.' && namelen == 2) {
1073                                         /*
1074                                          * skip ".."
1075                                          */
1076                                         continue;
1077                                 } else if (!sai->sai_ls_all) {
1078                                         /*
1079                                          * skip hidden files.
1080                                          */
1081                                         sai->sai_skip_hidden++;
1082                                         continue;
1083                                 }
1084                         }
1085
1086                         /*
1087                          * don't stat-ahead first entry.
1088                          */
1089                         if (unlikely(++first == 1))
1090                                 continue;
1091
1092                         fid_le_to_cpu(&fid, &ent->lde_fid);
1093
1094                         /* wait for spare statahead window */
1095                         do {
1096                                 l_wait_event(sa_thread->t_ctl_waitq,
1097                                              !sa_sent_full(sai) ||
1098                                              sa_has_callback(sai) ||
1099                                              !agl_list_empty(sai) ||
1100                                              !thread_is_running(sa_thread),
1101                                              &lwi);
1102
1103                                 sa_handle_callback(sai);
1104
1105                                 spin_lock(&lli->lli_agl_lock);
1106                                 while (sa_sent_full(sai) &&
1107                                        !agl_list_empty(sai)) {
1108                                         struct ll_inode_info *clli;
1109
1110                                         clli = agl_first_entry(sai);
1111                                         list_del_init(&clli->lli_agl_list);
1112                                         spin_unlock(&lli->lli_agl_lock);
1113
1114                                         ll_agl_trigger(&clli->lli_vfs_inode,
1115                                                         sai);
1116                                         cond_resched();
1117                                         spin_lock(&lli->lli_agl_lock);
1118                                 }
1119                                 spin_unlock(&lli->lli_agl_lock);
1120                         } while (sa_sent_full(sai) &&
1121                                  thread_is_running(sa_thread));
1122
1123                         sa_statahead(parent, name, namelen, &fid);
1124                 }
1125
1126                 pos = le64_to_cpu(dp->ldp_hash_end);
1127                 ll_release_page(dir, page,
1128                                 le32_to_cpu(dp->ldp_flags) & LDF_COLLIDE);
1129
1130                 if (sa_low_hit(sai)) {
1131                         rc = -EFAULT;
1132                         atomic_inc(&sbi->ll_sa_wrong);
1133                         CDEBUG(D_READA, "Statahead for dir "DFID" hit "
1134                                "ratio too low: hit/miss %llu/%llu"
1135                                ", sent/replied %llu/%llu, stopping "
1136                                "statahead thread: pid %d\n",
1137                                PFID(&lli->lli_fid), sai->sai_hit,
1138                                sai->sai_miss, sai->sai_sent,
1139                                sai->sai_replied, current_pid());
1140                         break;
1141                 }
1142         }
1143         ll_dir_chain_fini(&chain);
1144         ll_finish_md_op_data(op_data);
1145
1146         if (rc < 0) {
1147                 spin_lock(&lli->lli_sa_lock);
1148                 thread_set_flags(sa_thread, SVC_STOPPING);
1149                 lli->lli_sa_enabled = 0;
1150                 spin_unlock(&lli->lli_sa_lock);
1151         }
1152
1153         /* statahead is finished, but statahead entries need to be cached, wait
1154          * for file release to stop me. */
1155         while (thread_is_running(sa_thread)) {
1156                 l_wait_event(sa_thread->t_ctl_waitq,
1157                              sa_has_callback(sai) ||
1158                              !thread_is_running(sa_thread),
1159                              &lwi);
1160
1161                 sa_handle_callback(sai);
1162         }
1163
1164         EXIT;
1165 out:
1166         if (sai->sai_agl_valid) {
1167                 spin_lock(&lli->lli_agl_lock);
1168                 thread_set_flags(agl_thread, SVC_STOPPING);
1169                 spin_unlock(&lli->lli_agl_lock);
1170                 wake_up(&agl_thread->t_ctl_waitq);
1171
1172                 CDEBUG(D_READA, "stop agl thread: sai %p pid %u\n",
1173                        sai, (unsigned int)agl_thread->t_pid);
1174                 l_wait_event(agl_thread->t_ctl_waitq,
1175                              thread_is_stopped(agl_thread),
1176                              &lwi);
1177         } else {
1178                 /* Set agl_thread flags anyway. */
1179                 thread_set_flags(agl_thread, SVC_STOPPED);
1180         }
1181
1182         /* wait for inflight statahead RPCs to finish, and then we can free sai
1183          * safely because statahead RPC will access sai data */
1184         while (sai->sai_sent != sai->sai_replied) {
1185                 /* in case we're not woken up, timeout wait */
1186                 lwi = LWI_TIMEOUT(msecs_to_jiffies(MSEC_PER_SEC >> 3),
1187                                   NULL, NULL);
1188                 l_wait_event(sa_thread->t_ctl_waitq,
1189                         sai->sai_sent == sai->sai_replied, &lwi);
1190         }
1191
1192         /* release resources held by statahead RPCs */
1193         sa_handle_callback(sai);
1194
1195         spin_lock(&lli->lli_sa_lock);
1196         thread_set_flags(sa_thread, SVC_STOPPED);
1197         spin_unlock(&lli->lli_sa_lock);
1198
1199         CDEBUG(D_READA, "statahead thread stopped: sai %p, parent %.*s\n",
1200                sai, parent->d_name.len, parent->d_name.name);
1201
1202         wake_up(&sai->sai_waitq);
1203         wake_up(&sa_thread->t_ctl_waitq);
1204         ll_sai_put(sai);
1205
1206         return rc;
1207 }
1208
1209 /* authorize opened dir handle @key to statahead */
1210 void ll_authorize_statahead(struct inode *dir, void *key)
1211 {
1212         struct ll_inode_info *lli = ll_i2info(dir);
1213
1214         spin_lock(&lli->lli_sa_lock);
1215         if (lli->lli_opendir_key == NULL && lli->lli_sai == NULL) {
1216                 /*
1217                  * if lli_sai is not NULL, it means previous statahead is not
1218                  * finished yet, we'd better not start a new statahead for now.
1219                  */
1220                 LASSERT(lli->lli_opendir_pid == 0);
1221                 lli->lli_opendir_key = key;
1222                 lli->lli_opendir_pid = current_pid();
1223                 lli->lli_sa_enabled = 1;
1224         }
1225         spin_unlock(&lli->lli_sa_lock);
1226 }
1227
1228 /*
1229  * deauthorize opened dir handle @key to statahead, and notify statahead thread
1230  * to quit if it's running.
1231  */
1232 void ll_deauthorize_statahead(struct inode *dir, void *key)
1233 {
1234         struct ll_inode_info *lli = ll_i2info(dir);
1235         struct ll_statahead_info *sai;
1236
1237         LASSERT(lli->lli_opendir_key == key);
1238         LASSERT(lli->lli_opendir_pid != 0);
1239
1240         CDEBUG(D_READA, "deauthorize statahead for "DFID"\n",
1241                 PFID(&lli->lli_fid));
1242
1243         spin_lock(&lli->lli_sa_lock);
1244         lli->lli_opendir_key = NULL;
1245         lli->lli_opendir_pid = 0;
1246         lli->lli_sa_enabled = 0;
1247         sai = lli->lli_sai;
1248         if (sai != NULL && thread_is_running(&sai->sai_thread)) {
1249                 /*
1250                  * statahead thread may not quit yet because it needs to cache
1251                  * entries, now it's time to tell it to quit.
1252                  *
1253                  * In case sai is released, wake_up() is called inside spinlock,
1254                  * so we have to call smp_mb() explicitely to serialize ops.
1255                  */
1256                 thread_set_flags(&sai->sai_thread, SVC_STOPPING);
1257                 smp_mb();
1258                 wake_up(&sai->sai_thread.t_ctl_waitq);
1259         }
1260         spin_unlock(&lli->lli_sa_lock);
1261 }
1262
1263 enum {
1264         /**
1265          * not first dirent, or is "."
1266          */
1267         LS_NOT_FIRST_DE = 0,
1268         /**
1269          * the first non-hidden dirent
1270          */
1271         LS_FIRST_DE,
1272         /**
1273          * the first hidden dirent, that is "."
1274          */
1275         LS_FIRST_DOT_DE
1276 };
1277
1278 /* file is first dirent under @dir */
1279 static int is_first_dirent(struct inode *dir, struct dentry *dentry)
1280 {
1281         struct ll_dir_chain   chain;
1282         struct qstr          *target = &dentry->d_name;
1283         struct md_op_data    *op_data;
1284         int                   dot_de;
1285         struct page          *page = NULL;
1286         int                   rc = LS_NOT_FIRST_DE;
1287         __u64                 pos = 0;
1288         ENTRY;
1289
1290         op_data = ll_prep_md_op_data(NULL, dir, dir, NULL, 0, 0,
1291                                      LUSTRE_OPC_ANY, dir);
1292         if (IS_ERR(op_data))
1293                 RETURN(PTR_ERR(op_data));
1294         /**
1295          *FIXME choose the start offset of the readdir
1296          */
1297
1298         ll_dir_chain_init(&chain);
1299         page = ll_get_dir_page(dir, op_data, 0, &chain);
1300
1301         while (1) {
1302                 struct lu_dirpage *dp;
1303                 struct lu_dirent  *ent;
1304
1305                 if (IS_ERR(page)) {
1306                         struct ll_inode_info *lli = ll_i2info(dir);
1307
1308                         rc = PTR_ERR(page);
1309                         CERROR("%s: reading dir "DFID" at %llu"
1310                                "opendir_pid = %u : rc = %d\n",
1311                                ll_get_fsname(dir->i_sb, NULL, 0),
1312                                PFID(ll_inode2fid(dir)), pos,
1313                                lli->lli_opendir_pid, rc);
1314                         break;
1315                 }
1316
1317                 dp = page_address(page);
1318                 for (ent = lu_dirent_start(dp); ent != NULL;
1319                      ent = lu_dirent_next(ent)) {
1320                         __u64 hash;
1321                         int namelen;
1322                         char *name;
1323
1324                         hash = le64_to_cpu(ent->lde_hash);
1325                         /* The ll_get_dir_page() can return any page containing
1326                          * the given hash which may be not the start hash. */
1327                         if (unlikely(hash < pos))
1328                                 continue;
1329
1330                         namelen = le16_to_cpu(ent->lde_namelen);
1331                         if (unlikely(namelen == 0))
1332                                 /*
1333                                  * skip dummy record.
1334                                  */
1335                                 continue;
1336
1337                         name = ent->lde_name;
1338                         if (name[0] == '.') {
1339                                 if (namelen == 1)
1340                                         /*
1341                                          * skip "."
1342                                          */
1343                                         continue;
1344                                 else if (name[1] == '.' && namelen == 2)
1345                                         /*
1346                                          * skip ".."
1347                                          */
1348                                         continue;
1349                                 else
1350                                         dot_de = 1;
1351                         } else {
1352                                 dot_de = 0;
1353                         }
1354
1355                         if (dot_de && target->name[0] != '.') {
1356                                 CDEBUG(D_READA, "%.*s skip hidden file %.*s\n",
1357                                        target->len, target->name,
1358                                        namelen, name);
1359                                 continue;
1360                         }
1361
1362                         if (target->len != namelen ||
1363                             memcmp(target->name, name, namelen) != 0)
1364                                 rc = LS_NOT_FIRST_DE;
1365                         else if (!dot_de)
1366                                 rc = LS_FIRST_DE;
1367                         else
1368                                 rc = LS_FIRST_DOT_DE;
1369
1370                         ll_release_page(dir, page, false);
1371                         GOTO(out, rc);
1372                 }
1373                 pos = le64_to_cpu(dp->ldp_hash_end);
1374                 if (pos == MDS_DIR_END_OFF) {
1375                         /*
1376                          * End of directory reached.
1377                          */
1378                         ll_release_page(dir, page, false);
1379                         GOTO(out, rc);
1380                 } else {
1381                         /*
1382                          * chain is exhausted
1383                          * Normal case: continue to the next page.
1384                          */
1385                         ll_release_page(dir, page, le32_to_cpu(dp->ldp_flags) &
1386                                               LDF_COLLIDE);
1387                         page = ll_get_dir_page(dir, op_data, pos, &chain);
1388                 }
1389         }
1390         EXIT;
1391 out:
1392         ll_dir_chain_fini(&chain);
1393         ll_finish_md_op_data(op_data);
1394         return rc;
1395 }
1396
1397 /**
1398  * revalidate @dentryp from statahead cache
1399  *
1400  * \param[in] dir       parent directory
1401  * \param[in] sai       sai structure
1402  * \param[out] dentryp  pointer to dentry which will be revalidated
1403  * \param[in] unplug    unplug statahead window only (normally for negative
1404  *                      dentry)
1405  * \retval              1 on success, dentry is saved in @dentryp
1406  * \retval              0 if revalidation failed (no proper lock on client)
1407  * \retval              negative number upon error
1408  */
1409 static int revalidate_statahead_dentry(struct inode *dir,
1410                                         struct ll_statahead_info *sai,
1411                                         struct dentry **dentryp,
1412                                         bool unplug)
1413 {
1414         struct sa_entry *entry = NULL;
1415         struct l_wait_info lwi = { 0 };
1416         struct ll_dentry_data *ldd;
1417         struct ll_inode_info *lli = ll_i2info(dir);
1418         int rc = 0;
1419         ENTRY;
1420
1421         if ((*dentryp)->d_name.name[0] == '.') {
1422                 if (sai->sai_ls_all ||
1423                     sai->sai_miss_hidden >= sai->sai_skip_hidden) {
1424                         /*
1425                          * Hidden dentry is the first one, or statahead
1426                          * thread does not skip so many hidden dentries
1427                          * before "sai_ls_all" enabled as below.
1428                          */
1429                 } else {
1430                         if (!sai->sai_ls_all)
1431                                 /*
1432                                  * It maybe because hidden dentry is not
1433                                  * the first one, "sai_ls_all" was not
1434                                  * set, then "ls -al" missed. Enable
1435                                  * "sai_ls_all" for such case.
1436                                  */
1437                                 sai->sai_ls_all = 1;
1438
1439                         /*
1440                          * Such "getattr" has been skipped before
1441                          * "sai_ls_all" enabled as above.
1442                          */
1443                         sai->sai_miss_hidden++;
1444                         RETURN(-EAGAIN);
1445                 }
1446         }
1447
1448         if (unplug)
1449                 GOTO(out, rc = 1);
1450
1451         entry = sa_get(sai, &(*dentryp)->d_name);
1452         if (entry == NULL)
1453                 GOTO(out, rc = -EAGAIN);
1454
1455         /* if statahead is busy in readdir, help it do post-work */
1456         if (!sa_ready(entry) && sai->sai_in_readpage)
1457                 sa_handle_callback(sai);
1458
1459         if (!sa_ready(entry)) {
1460                 spin_lock(&lli->lli_sa_lock);
1461                 sai->sai_index_wait = entry->se_index;
1462                 spin_unlock(&lli->lli_sa_lock);
1463                 lwi = LWI_TIMEOUT_INTR(cfs_time_seconds(30), NULL,
1464                                        LWI_ON_SIGNAL_NOOP, NULL);
1465                 rc = l_wait_event(sai->sai_waitq, sa_ready(entry), &lwi);
1466                 if (rc < 0) {
1467                         /*
1468                          * entry may not be ready, so it may be used by inflight
1469                          * statahead RPC, don't free it.
1470                          */
1471                         entry = NULL;
1472                         GOTO(out, rc = -EAGAIN);
1473                 }
1474         }
1475
1476         if (entry->se_state == SA_ENTRY_SUCC && entry->se_inode != NULL) {
1477                 struct inode *inode = entry->se_inode;
1478                 struct lookup_intent it = { .it_op = IT_GETATTR,
1479                                             .it_lock_handle =
1480                                                 entry->se_handle };
1481                 __u64 bits;
1482
1483                 rc = md_revalidate_lock(ll_i2mdexp(dir), &it,
1484                                         ll_inode2fid(inode), &bits);
1485                 if (rc == 1) {
1486                         if ((*dentryp)->d_inode == NULL) {
1487                                 struct dentry *alias;
1488
1489                                 alias = ll_splice_alias(inode, *dentryp);
1490                                 if (IS_ERR(alias)) {
1491                                         ll_intent_release(&it);
1492                                         GOTO(out, rc = PTR_ERR(alias));
1493                                 }
1494                                 *dentryp = alias;
1495                                 /* statahead prepared this inode, transfer inode
1496                                  * refcount from sa_entry to dentry */
1497                                 entry->se_inode = NULL;
1498                         } else if ((*dentryp)->d_inode != inode) {
1499                                 /* revalidate, but inode is recreated */
1500                                 CDEBUG(D_READA,
1501                                         "%s: stale dentry %.*s inode "
1502                                         DFID", statahead inode "DFID
1503                                         "\n",
1504                                         ll_get_fsname((*dentryp)->d_inode->i_sb,
1505                                                       NULL, 0),
1506                                         (*dentryp)->d_name.len,
1507                                         (*dentryp)->d_name.name,
1508                                         PFID(ll_inode2fid((*dentryp)->d_inode)),
1509                                         PFID(ll_inode2fid(inode)));
1510                                 ll_intent_release(&it);
1511                                 GOTO(out, rc = -ESTALE);
1512                         }
1513
1514                         if ((bits & MDS_INODELOCK_LOOKUP) &&
1515                             d_lustre_invalid(*dentryp))
1516                                 d_lustre_revalidate(*dentryp);
1517                         ll_intent_release(&it);
1518                 }
1519         }
1520 out:
1521         /*
1522          * statahead cached sa_entry can be used only once, and will be killed
1523          * right after use, so if lookup/revalidate accessed statahead cache,
1524          * set dentry ldd_sa_generation to parent lli_sa_generation, later if we
1525          * stat this file again, we know we've done statahead before, see
1526          * dentry_may_statahead().
1527          */
1528         ldd = ll_d2d(*dentryp);
1529         /* ldd can be NULL if llite lookup failed. */
1530         if (ldd != NULL)
1531                 ldd->lld_sa_generation = lli->lli_sa_generation;
1532         sa_put(sai, entry);
1533
1534         RETURN(rc);
1535 }
1536
1537 /**
1538  * start statahead thread
1539  *
1540  * \param[in] dir       parent directory
1541  * \param[in] dentry    dentry that triggers statahead, normally the first
1542  *                      dirent under @dir
1543  * \retval              -EAGAIN on success, because when this function is
1544  *                      called, it's already in lookup call, so client should
1545  *                      do it itself instead of waiting for statahead thread
1546  *                      to do it asynchronously.
1547  * \retval              negative number upon error
1548  */
1549 static int start_statahead_thread(struct inode *dir, struct dentry *dentry)
1550 {
1551         struct ll_inode_info *lli = ll_i2info(dir);
1552         struct ll_statahead_info *sai = NULL;
1553         struct dentry *parent = dentry->d_parent;
1554         struct ptlrpc_thread *thread;
1555         struct l_wait_info lwi = { 0 };
1556         struct task_struct *task;
1557         struct ll_sb_info *sbi = ll_i2sbi(parent->d_inode);
1558         int first = LS_FIRST_DE;
1559         int rc = 0;
1560         ENTRY;
1561
1562         /* I am the "lli_opendir_pid" owner, only me can set "lli_sai". */
1563         first = is_first_dirent(dir, dentry);
1564         if (first == LS_NOT_FIRST_DE)
1565                 /* It is not "ls -{a}l" operation, no need statahead for it. */
1566                 GOTO(out, rc = -EFAULT);
1567
1568         if (unlikely(atomic_inc_return(&sbi->ll_sa_running) >
1569                                        sbi->ll_sa_running_max)) {
1570                 CDEBUG(D_READA,
1571                        "Too many concurrent statahead instances, "
1572                        "avoid new statahead instance temporarily.\n");
1573                 GOTO(out, rc = -EMFILE);
1574         }
1575
1576         sai = ll_sai_alloc(parent);
1577         if (sai == NULL)
1578                 GOTO(out, rc = -ENOMEM);
1579
1580         sai->sai_ls_all = (first == LS_FIRST_DOT_DE);
1581
1582         /* if current lli_opendir_key was deauthorized, or dir re-opened by
1583          * another process, don't start statahead, otherwise the newly spawned
1584          * statahead thread won't be notified to quit. */
1585         spin_lock(&lli->lli_sa_lock);
1586         if (unlikely(lli->lli_sai != NULL ||
1587                      lli->lli_opendir_key == NULL ||
1588                      lli->lli_opendir_pid != current->pid)) {
1589                 spin_unlock(&lli->lli_sa_lock);
1590                 GOTO(out, rc = -EPERM);
1591         }
1592         lli->lli_sai = sai;
1593         spin_unlock(&lli->lli_sa_lock);
1594
1595         CDEBUG(D_READA, "start statahead thread: [pid %d] [parent %.*s]\n",
1596                current_pid(), parent->d_name.len, parent->d_name.name);
1597
1598         task = kthread_run(ll_statahead_thread, parent, "ll_sa_%u",
1599                            lli->lli_opendir_pid);
1600         thread = &sai->sai_thread;
1601         if (IS_ERR(task)) {
1602                 spin_lock(&lli->lli_sa_lock);
1603                 lli->lli_sai = NULL;
1604                 spin_unlock(&lli->lli_sa_lock);
1605                 rc = PTR_ERR(task);
1606                 CERROR("can't start ll_sa thread, rc: %d\n", rc);
1607                 GOTO(out, rc);
1608         }
1609
1610         l_wait_event(thread->t_ctl_waitq,
1611                      thread_is_running(thread) || thread_is_stopped(thread),
1612                      &lwi);
1613         ll_sai_put(sai);
1614
1615         /*
1616          * We don't stat-ahead for the first dirent since we are already in
1617          * lookup.
1618          */
1619         RETURN(-EAGAIN);
1620
1621 out:
1622         /* once we start statahead thread failed, disable statahead so that
1623          * subsequent stat won't waste time to try it. */
1624         spin_lock(&lli->lli_sa_lock);
1625         if (lli->lli_opendir_pid == current->pid)
1626                 lli->lli_sa_enabled = 0;
1627         spin_unlock(&lli->lli_sa_lock);
1628
1629         if (sai != NULL)
1630                 ll_sai_free(sai);
1631         if (first != LS_NOT_FIRST_DE)
1632                 atomic_dec(&sbi->ll_sa_running);
1633
1634         RETURN(rc);
1635 }
1636
1637 /**
1638  * statahead entry function, this is called when client getattr on a file, it
1639  * will start statahead thread if this is the first dir entry, else revalidate
1640  * dentry from statahead cache.
1641  *
1642  * \param[in]  dir      parent directory
1643  * \param[out] dentryp  dentry to getattr
1644  * \param[in]  unplug   unplug statahead window only (normally for negative
1645  *                      dentry)
1646  * \retval              1 on success
1647  * \retval              0 revalidation from statahead cache failed, caller needs
1648  *                      to getattr from server directly
1649  * \retval              negative number on error, caller often ignores this and
1650  *                      then getattr from server
1651  */
1652 int ll_statahead(struct inode *dir, struct dentry **dentryp, bool unplug)
1653 {
1654         struct ll_statahead_info *sai;
1655
1656         sai = ll_sai_get(dir);
1657         if (sai != NULL) {
1658                 int rc;
1659
1660                 rc = revalidate_statahead_dentry(dir, sai, dentryp, unplug);
1661                 CDEBUG(D_READA, "revalidate statahead %.*s: %d.\n",
1662                         (*dentryp)->d_name.len, (*dentryp)->d_name.name, rc);
1663                 ll_sai_put(sai);
1664                 return rc;
1665         }
1666         return start_statahead_thread(dir, *dentryp);
1667 }