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  */
  31
  32 #include <linux/fs.h>
  33 #include <linux/sched.h>
  34 #include <linux/kthread.h>
  35 #include <linux/mm.h>
  36 #include <linux/highmem.h>
  37 #include <linux/pagemap.h>
  38 #include <linux/delay.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 /*
  56  * sa_entry is not refcounted: statahead thread allocates it and do async stat,
  57  * and in async stat callback ll_statahead_interpret() will add it into
  58  * sai_interim_entries, later statahead thread will call sa_handle_callback() to
  59  * instantiate entry and move it into sai_entries, and then only scanner process
  60  * can access and free it.
  61  */
  62 struct sa_entry {
  63         /* link into sai_interim_entries or sai_entries */
  64         struct list_head        se_list;
  65         /* link into sai hash table locally */
  66         struct list_head        se_hash;
  67         /* entry index in the sai */
  68         __u64                   se_index;
  69         /* low layer ldlm lock handle */
  70         __u64                   se_handle;
  71         /* entry status */
  72         se_state_t              se_state;
  73         /* entry size, contains name */
  74         int                     se_size;
  75         /* pointer to async getattr enqueue info */
  76         struct md_enqueue_info *se_minfo;
  77         /* pointer to the async getattr request */
  78         struct ptlrpc_request  *se_req;
  79         /* pointer to the target inode */
  80         struct inode           *se_inode;
  81         /* entry name */
  82         struct qstr             se_qstr;
  83         /* entry fid */
  84         struct lu_fid           se_fid;
  85 };
  86
  87 static unsigned int sai_generation;
  88 static DEFINE_SPINLOCK(sai_generation_lock);
  89
  90 static inline int sa_unhashed(struct sa_entry *entry)
  91 {
  92         return list_empty(&entry->se_hash);
  93 }
  94
  95 /* sa_entry is ready to use */
  96 static inline int sa_ready(struct sa_entry *entry)
  97 {
  98         /* Make sure sa_entry is updated and ready to use */
  99         smp_rmb();
 100         return (entry->se_state != SA_ENTRY_INIT);
 101 }
 102
 103 /* hash value to put in sai_cache */
 104 static inline int sa_hash(int val)
 105 {
 106         return val & LL_SA_CACHE_MASK;
 107 }
 108
 109 /* hash entry into sai_cache */
 110 static inline void
 111 sa_rehash(struct ll_statahead_info *sai, struct sa_entry *entry)
 112 {
 113         int i = sa_hash(entry->se_qstr.hash);
 114
 115         spin_lock(&sai->sai_cache_lock[i]);
 116         list_add_tail(&entry->se_hash, &sai->sai_cache[i]);
 117         spin_unlock(&sai->sai_cache_lock[i]);
 118 }
 119
 120 /* unhash entry from sai_cache */
 121 static inline void
 122 sa_unhash(struct ll_statahead_info *sai, struct sa_entry *entry)
 123 {
 124         int i = sa_hash(entry->se_qstr.hash);
 125
 126         spin_lock(&sai->sai_cache_lock[i]);
 127         list_del_init(&entry->se_hash);
 128         spin_unlock(&sai->sai_cache_lock[i]);
 129 }
 130
 131 static inline int agl_should_run(struct ll_statahead_info *sai,
 132                                  struct inode *inode)
 133 {
 134         return inode && S_ISREG(inode->i_mode) && sai->sai_agl_task;
 135 }
 136
 137 static inline struct ll_inode_info *
 138 agl_first_entry(struct ll_statahead_info *sai)
 139 {
 140         return list_entry(sai->sai_agls.next, struct ll_inode_info,
 141                           lli_agl_list);
 142 }
 143
 144 /* statahead window is full */
 145 static inline int sa_sent_full(struct ll_statahead_info *sai)
 146 {
 147         return atomic_read(&sai->sai_cache_count) >= sai->sai_max;
 148 }
 149
 150 /* got async stat replies */
 151 static inline int sa_has_callback(struct ll_statahead_info *sai)
 152 {
 153         return !list_empty(&sai->sai_interim_entries);
 154 }
 155
 156 static inline int agl_list_empty(struct ll_statahead_info *sai)
 157 {
 158         return list_empty(&sai->sai_agls);
 159 }
 160
 161 /**
 162  * (1) hit ratio less than 80%
 163  * or
 164  * (2) consecutive miss more than 8
 165  * then means low hit.
 166  */
 167 static inline int sa_low_hit(struct ll_statahead_info *sai)
 168 {
 169         return ((sai->sai_hit > 7 && sai->sai_hit < 4 * sai->sai_miss) ||
 170                 (sai->sai_consecutive_miss > 8));
 171 }
 172
 173 /*
 174  * if the given index is behind of statahead window more than
 175  * SA_OMITTED_ENTRY_MAX, then it is old.
 176  */
 177 static inline int is_omitted_entry(struct ll_statahead_info *sai, __u64 index)
 178 {
 179         return ((__u64)sai->sai_max + index + SA_OMITTED_ENTRY_MAX <
 180                 sai->sai_index);
 181 }
 182
 183 /* allocate sa_entry and hash it to allow scanner process to find it */
 184 static struct sa_entry *
 185 sa_alloc(struct dentry *parent, struct ll_statahead_info *sai, __u64 index,
 186          const char *name, int len, const struct lu_fid *fid)
 187 {
 188         struct ll_inode_info *lli;
 189         struct sa_entry *entry;
 190         int entry_size;
 191         char *dname;
 192
 193         ENTRY;
 194
 195         entry_size = sizeof(struct sa_entry) + (len & ~3) + 4;
 196         OBD_ALLOC(entry, entry_size);
 197         if (unlikely(!entry))
 198                 RETURN(ERR_PTR(-ENOMEM));
 199
 200         CDEBUG(D_READA, "alloc sa entry %.*s(%p) index %llu\n",
 201                len, name, entry, index);
 202
 203         entry->se_index = index;
 204
 205         entry->se_state = SA_ENTRY_INIT;
 206         entry->se_size = entry_size;
 207         dname = (char *)entry + sizeof(struct sa_entry);
 208         memcpy(dname, name, len);
 209         dname[len] = 0;
 210         entry->se_qstr.hash = ll_full_name_hash(parent, name, len);
 211         entry->se_qstr.len = len;
 212         entry->se_qstr.name = dname;
 213         entry->se_fid = *fid;
 214
 215         lli = ll_i2info(sai->sai_dentry->d_inode);
 216
 217         spin_lock(&lli->lli_sa_lock);
 218         INIT_LIST_HEAD(&entry->se_list);
 219         sa_rehash(sai, entry);
 220         spin_unlock(&lli->lli_sa_lock);
 221
 222         atomic_inc(&sai->sai_cache_count);
 223
 224         RETURN(entry);
 225 }
 226
 227 /* free sa_entry, which should have been unhashed and not in any list */
 228 static void sa_free(struct ll_statahead_info *sai, struct sa_entry *entry)
 229 {
 230         CDEBUG(D_READA, "free sa entry %.*s(%p) index %llu\n",
 231                entry->se_qstr.len, entry->se_qstr.name, entry,
 232                entry->se_index);
 233
 234         LASSERT(list_empty(&entry->se_list));
 235         LASSERT(sa_unhashed(entry));
 236
 237         OBD_FREE(entry, entry->se_size);
 238         atomic_dec(&sai->sai_cache_count);
 239 }
 240
 241 /*
 242  * find sa_entry by name, used by directory scanner, lock is not needed because
 243  * only scanner can remove the entry from cache.
 244  */
 245 static struct sa_entry *
 246 sa_get(struct ll_statahead_info *sai, const struct qstr *qstr)
 247 {
 248         struct sa_entry *entry;
 249         int i = sa_hash(qstr->hash);
 250
 251         list_for_each_entry(entry, &sai->sai_cache[i], se_hash) {
 252                 if (entry->se_qstr.hash == qstr->hash &&
 253                     entry->se_qstr.len == qstr->len &&
 254                     memcmp(entry->se_qstr.name, qstr->name, qstr->len) == 0)
 255                         return entry;
 256         }
 257         return NULL;
 258 }
 259
 260 /* unhash and unlink sa_entry, and then free it */
 261 static inline void
 262 sa_kill(struct ll_statahead_info *sai, struct sa_entry *entry)
 263 {
 264         struct ll_inode_info *lli = ll_i2info(sai->sai_dentry->d_inode);
 265
 266         LASSERT(!sa_unhashed(entry));
 267         LASSERT(!list_empty(&entry->se_list));
 268         LASSERT(sa_ready(entry));
 269
 270         sa_unhash(sai, entry);
 271
 272         spin_lock(&lli->lli_sa_lock);
 273         list_del_init(&entry->se_list);
 274         spin_unlock(&lli->lli_sa_lock);
 275
 276         iput(entry->se_inode);
 277
 278         sa_free(sai, entry);
 279 }
 280
 281 /* called by scanner after use, sa_entry will be killed */
 282 static void
 283 sa_put(struct ll_statahead_info *sai, struct sa_entry *entry)
 284 {
 285         struct sa_entry *tmp, *next;
 286
 287         if (entry && entry->se_state == SA_ENTRY_SUCC) {
 288                 struct ll_sb_info *sbi = ll_i2sbi(sai->sai_dentry->d_inode);
 289
 290                 sai->sai_hit++;
 291                 sai->sai_consecutive_miss = 0;
 292                 sai->sai_max = min(2 * sai->sai_max, sbi->ll_sa_max);
 293         } else {
 294                 sai->sai_miss++;
 295                 sai->sai_consecutive_miss++;
 296         }
 297
 298         if (entry)
 299                 sa_kill(sai, entry);
 300
 301         /*
 302          * kill old completed entries, only scanner process does this, no need
 303          * to lock
 304          */
 305         list_for_each_entry_safe(tmp, next, &sai->sai_entries, se_list) {
 306                 if (!is_omitted_entry(sai, tmp->se_index))
 307                         break;
 308                 sa_kill(sai, tmp);
 309         }
 310 }
 311
 312 /*
 313  * update state and sort add entry to sai_entries by index, return true if
 314  * scanner is waiting on this entry.
 315  */
 316 static bool
 317 __sa_make_ready(struct ll_statahead_info *sai, struct sa_entry *entry, int ret)
 318 {
 319         struct sa_entry *se;
 320         struct list_head *pos = &sai->sai_entries;
 321         __u64 index = entry->se_index;
 322
 323         LASSERT(!sa_ready(entry));
 324         LASSERT(list_empty(&entry->se_list));
 325
 326         list_for_each_entry_reverse(se, &sai->sai_entries, se_list) {
 327                 if (se->se_index < entry->se_index) {
 328                         pos = &se->se_list;
 329                         break;
 330                 }
 331         }
 332         list_add(&entry->se_list, pos);
 333         /*
 334          * LU-9210: ll_statahead_interpet must be able to see this before
 335          * we wake it up
 336          */
 337         smp_store_release(&entry->se_state,
 338                           ret < 0 ? SA_ENTRY_INVA : SA_ENTRY_SUCC);
 339
 340         return (index == sai->sai_index_wait);
 341 }
 342
 343 /* finish async stat RPC arguments */
 344 static void sa_fini_data(struct md_enqueue_info *minfo)
 345 {
 346         ll_unlock_md_op_lsm(&minfo->mi_data);
 347         iput(minfo->mi_dir);
 348         OBD_FREE_PTR(minfo);
 349 }
 350
 351 static int ll_statahead_interpret(struct ptlrpc_request *req,
 352                                   struct md_enqueue_info *minfo, int rc);
 353
 354 /*
 355  * prepare arguments for async stat RPC.
 356  */
 357 static struct md_enqueue_info *
 358 sa_prep_data(struct inode *dir, struct inode *child, struct sa_entry *entry)
 359 {
 360         struct md_enqueue_info   *minfo;
 361         struct ldlm_enqueue_info *einfo;
 362         struct md_op_data        *op_data;
 363
 364         OBD_ALLOC_PTR(minfo);
 365         if (!minfo)
 366                 return ERR_PTR(-ENOMEM);
 367
 368         op_data = ll_prep_md_op_data(&minfo->mi_data, dir, child,
 369                                      entry->se_qstr.name, entry->se_qstr.len, 0,
 370                                      LUSTRE_OPC_ANY, NULL);
 371         if (IS_ERR(op_data)) {
 372                 OBD_FREE_PTR(minfo);
 373                 return (struct md_enqueue_info *)op_data;
 374         }
 375
 376         if (!child)
 377                 op_data->op_fid2 = entry->se_fid;
 378
 379         minfo->mi_it.it_op = IT_GETATTR;
 380         minfo->mi_dir = igrab(dir);
 381         minfo->mi_cb = ll_statahead_interpret;
 382         minfo->mi_cbdata = entry;
 383
 384         einfo = &minfo->mi_einfo;
 385         einfo->ei_type   = LDLM_IBITS;
 386         einfo->ei_mode   = it_to_lock_mode(&minfo->mi_it);
 387         einfo->ei_cb_bl  = ll_md_blocking_ast;
 388         einfo->ei_cb_cp  = ldlm_completion_ast;
 389         einfo->ei_cb_gl  = NULL;
 390         einfo->ei_cbdata = NULL;
 391
 392         return minfo;
 393 }
 394
 395 /*
 396  * release resources used in async stat RPC, update entry state and wakeup if
 397  * scanner process it waiting on this entry.
 398  */
 399 static void
 400 sa_make_ready(struct ll_statahead_info *sai, struct sa_entry *entry, int ret)
 401 {
 402         struct ll_inode_info *lli = ll_i2info(sai->sai_dentry->d_inode);
 403         struct md_enqueue_info *minfo = entry->se_minfo;
 404         struct ptlrpc_request *req = entry->se_req;
 405         bool wakeup;
 406
 407         /* release resources used in RPC */
 408         if (minfo) {
 409                 entry->se_minfo = NULL;
 410                 ll_intent_release(&minfo->mi_it);
 411                 sa_fini_data(minfo);
 412         }
 413
 414         if (req) {
 415                 entry->se_req = NULL;
 416                 ptlrpc_req_finished(req);
 417         }
 418
 419         spin_lock(&lli->lli_sa_lock);
 420         wakeup = __sa_make_ready(sai, entry, ret);
 421         spin_unlock(&lli->lli_sa_lock);
 422
 423         if (wakeup)
 424                 wake_up(&sai->sai_waitq);
 425 }
 426
 427 /* insert inode into the list of sai_agls */
 428 static void ll_agl_add(struct ll_statahead_info *sai,
 429                        struct inode *inode, int index)
 430 {
 431         struct ll_inode_info *child  = ll_i2info(inode);
 432         struct ll_inode_info *parent = ll_i2info(sai->sai_dentry->d_inode);
 433
 434         spin_lock(&child->lli_agl_lock);
 435         if (child->lli_agl_index == 0) {
 436                 child->lli_agl_index = index;
 437                 spin_unlock(&child->lli_agl_lock);
 438
 439                 LASSERT(list_empty(&child->lli_agl_list));
 440
 441                 spin_lock(&parent->lli_agl_lock);
 442                 /* Re-check under the lock */
 443                 if (agl_should_run(sai, inode)) {
 444                         if (agl_list_empty(sai))
 445                                 wake_up_process(sai->sai_agl_task);
 446                         igrab(inode);
 447                         list_add_tail(&child->lli_agl_list, &sai->sai_agls);
 448                 } else
 449                         child->lli_agl_index = 0;
 450                 spin_unlock(&parent->lli_agl_lock);
 451         } else {
 452                 spin_unlock(&child->lli_agl_lock);
 453         }
 454 }
 455
 456 /* allocate sai */
 457 static struct ll_statahead_info *ll_sai_alloc(struct dentry *dentry)
 458 {
 459         struct ll_statahead_info *sai;
 460         struct ll_inode_info *lli = ll_i2info(dentry->d_inode);
 461         int i;
 462
 463         ENTRY;
 464
 465         OBD_ALLOC_PTR(sai);
 466         if (!sai)
 467                 RETURN(NULL);
 468
 469         sai->sai_dentry = dget(dentry);
 470         atomic_set(&sai->sai_refcount, 1);
 471         sai->sai_max = LL_SA_RPC_MIN;
 472         sai->sai_index = 1;
 473         init_waitqueue_head(&sai->sai_waitq);
 474
 475         INIT_LIST_HEAD(&sai->sai_interim_entries);
 476         INIT_LIST_HEAD(&sai->sai_entries);
 477         INIT_LIST_HEAD(&sai->sai_agls);
 478
 479         for (i = 0; i < LL_SA_CACHE_SIZE; i++) {
 480                 INIT_LIST_HEAD(&sai->sai_cache[i]);
 481                 spin_lock_init(&sai->sai_cache_lock[i]);
 482         }
 483         atomic_set(&sai->sai_cache_count, 0);
 484
 485         spin_lock(&sai_generation_lock);
 486         lli->lli_sa_generation = ++sai_generation;
 487         if (unlikely(sai_generation == 0))
 488                 lli->lli_sa_generation = ++sai_generation;
 489         spin_unlock(&sai_generation_lock);
 490
 491         RETURN(sai);
 492 }
 493
 494 /* free sai */
 495 static inline void ll_sai_free(struct ll_statahead_info *sai)
 496 {
 497         LASSERT(sai->sai_dentry != NULL);
 498         dput(sai->sai_dentry);
 499         OBD_FREE_PTR(sai);
 500 }
 501
 502 /*
 503  * take refcount of sai if sai for @dir exists, which means statahead is on for
 504  * this directory.
 505  */
 506 static inline struct ll_statahead_info *ll_sai_get(struct inode *dir)
 507 {
 508         struct ll_inode_info *lli = ll_i2info(dir);
 509         struct ll_statahead_info *sai = NULL;
 510
 511         spin_lock(&lli->lli_sa_lock);
 512         sai = lli->lli_sai;
 513         if (sai)
 514                 atomic_inc(&sai->sai_refcount);
 515         spin_unlock(&lli->lli_sa_lock);
 516
 517         return sai;
 518 }
 519
 520 /*
 521  * put sai refcount after use, if refcount reaches zero, free sai and sa_entries
 522  * attached to it.
 523  */
 524 static void ll_sai_put(struct ll_statahead_info *sai)
 525 {
 526         struct ll_inode_info *lli = ll_i2info(sai->sai_dentry->d_inode);
 527
 528         if (atomic_dec_and_lock(&sai->sai_refcount, &lli->lli_sa_lock)) {
 529                 struct sa_entry *entry, *next;
 530                 struct ll_sb_info *sbi = ll_i2sbi(sai->sai_dentry->d_inode);
 531
 532                 lli->lli_sai = NULL;
 533                 spin_unlock(&lli->lli_sa_lock);
 534
 535                 LASSERT(!sai->sai_task);
 536                 LASSERT(!sai->sai_agl_task);
 537                 LASSERT(sai->sai_sent == sai->sai_replied);
 538                 LASSERT(!sa_has_callback(sai));
 539
 540                 list_for_each_entry_safe(entry, next, &sai->sai_entries,
 541                                          se_list)
 542                         sa_kill(sai, entry);
 543
 544                 LASSERT(atomic_read(&sai->sai_cache_count) == 0);
 545                 LASSERT(agl_list_empty(sai));
 546
 547                 ll_sai_free(sai);
 548                 atomic_dec(&sbi->ll_sa_running);
 549         }
 550 }
 551
 552 /* Do NOT forget to drop inode refcount when into sai_agls. */
 553 static void ll_agl_trigger(struct inode *inode, struct ll_statahead_info *sai)
 554 {
 555         struct ll_inode_info *lli = ll_i2info(inode);
 556         u64 index = lli->lli_agl_index;
 557         ktime_t expire;
 558         int rc;
 559
 560         ENTRY;
 561
 562         LASSERT(list_empty(&lli->lli_agl_list));
 563
 564         /* AGL maybe fall behind statahead with one entry */
 565         if (is_omitted_entry(sai, index + 1)) {
 566                 lli->lli_agl_index = 0;
 567                 iput(inode);
 568                 RETURN_EXIT;
 569         }
 570
 571         /*
 572          * In case of restore, the MDT has the right size and has already
 573          * sent it back without granting the layout lock, inode is up-to-date.
 574          * Then AGL (async glimpse lock) is useless.
 575          * Also to glimpse we need the layout, in case of a runninh restore
 576          * the MDT holds the layout lock so the glimpse will block up to the
 577          * end of restore (statahead/agl will block)
 578          */
 579         if (test_bit(LLIF_FILE_RESTORING, &lli->lli_flags)) {
 580                 lli->lli_agl_index = 0;
 581                 iput(inode);
 582                 RETURN_EXIT;
 583         }
 584
 585         /* Someone is in glimpse (sync or async), do nothing. */
 586         rc = down_write_trylock(&lli->lli_glimpse_sem);
 587         if (rc == 0) {
 588                 lli->lli_agl_index = 0;
 589                 iput(inode);
 590                 RETURN_EXIT;
 591         }
 592
 593         /*
 594          * Someone triggered glimpse within 1 sec before.
 595          * 1) The former glimpse succeeded with glimpse lock granted by OST, and
 596          *    if the lock is still cached on client, AGL needs to do nothing. If
 597          *    it is cancelled by other client, AGL maybe cannot obtaion new lock
 598          *    for no glimpse callback triggered by AGL.
 599          * 2) The former glimpse succeeded, but OST did not grant glimpse lock.
 600          *    Under such case, it is quite possible that the OST will not grant
 601          *    glimpse lock for AGL also.
 602          * 3) The former glimpse failed, compared with other two cases, it is
 603          *    relative rare. AGL can ignore such case, and it will not muchly
 604          *    affect the performance.
 605          */
 606         expire = ktime_sub_ns(ktime_get(), NSEC_PER_SEC);
 607         if (ktime_to_ns(lli->lli_glimpse_time) &&
 608             ktime_before(expire, lli->lli_glimpse_time)) {
 609                 up_write(&lli->lli_glimpse_sem);
 610                 lli->lli_agl_index = 0;
 611                 iput(inode);
 612                 RETURN_EXIT;
 613         }
 614
 615         CDEBUG(D_READA,
 616                "Handling (init) async glimpse: inode = " DFID", idx = %llu\n",
 617                PFID(&lli->lli_fid), index);
 618
 619         cl_agl(inode);
 620         lli->lli_agl_index = 0;
 621         lli->lli_glimpse_time = ktime_get();
 622         up_write(&lli->lli_glimpse_sem);
 623
 624         CDEBUG(D_READA,
 625                "Handled (init) async glimpse: inode= " DFID", idx = %llu, rc = %d\n",
 626                PFID(&lli->lli_fid), index, rc);
 627
 628         iput(inode);
 629
 630         EXIT;
 631 }
 632
 633 /*
 634  * prepare inode for sa entry, add it into agl list, now sa_entry is ready
 635  * to be used by scanner process.
 636  */
 637 static void sa_instantiate(struct ll_statahead_info *sai,
 638                            struct sa_entry *entry)
 639 {
 640         struct inode *dir = sai->sai_dentry->d_inode;
 641         struct inode *child;
 642         struct md_enqueue_info *minfo;
 643         struct lookup_intent *it;
 644         struct ptlrpc_request *req;
 645         struct mdt_body *body;
 646         int rc = 0;
 647
 648         ENTRY;
 649
 650         LASSERT(entry->se_handle != 0);
 651
 652         minfo = entry->se_minfo;
 653         it = &minfo->mi_it;
 654         req = entry->se_req;
 655         body = req_capsule_server_get(&req->rq_pill, &RMF_MDT_BODY);
 656         if (!body)
 657                 GOTO(out, rc = -EFAULT);
 658
 659         child = entry->se_inode;
 660         /* revalidate; unlinked and re-created with the same name */
 661         if (unlikely(!lu_fid_eq(&minfo->mi_data.op_fid2, &body->mbo_fid1))) {
 662                 if (child) {
 663                         entry->se_inode = NULL;
 664                         iput(child);
 665                 }
 666                 /* The mdt_body is invalid. Skip this entry */
 667                 GOTO(out, rc = -EAGAIN);
 668         }
 669
 670         it->it_lock_handle = entry->se_handle;
 671         rc = md_revalidate_lock(ll_i2mdexp(dir), it, ll_inode2fid(dir), NULL);
 672         if (rc != 1)
 673                 GOTO(out, rc = -EAGAIN);
 674
 675         rc = ll_prep_inode(&child, &req->rq_pill, dir->i_sb, it);
 676         if (rc)
 677                 GOTO(out, rc);
 678
 679         CDEBUG(D_READA, "%s: setting %.*s"DFID" l_data to inode %p\n",
 680                ll_i2sbi(dir)->ll_fsname, entry->se_qstr.len,
 681                entry->se_qstr.name, PFID(ll_inode2fid(child)), child);
 682         ll_set_lock_data(ll_i2sbi(dir)->ll_md_exp, child, it, NULL);
 683
 684         entry->se_inode = child;
 685
 686         if (agl_should_run(sai, child))
 687                 ll_agl_add(sai, child, entry->se_index);
 688
 689         EXIT;
 690
 691 out:
 692         /*
 693          * sa_make_ready() will drop ldlm ibits lock refcount by calling
 694          * ll_intent_drop_lock() in spite of failures. Do not worry about
 695          * calling ll_intent_drop_lock() more than once.
 696          */
 697         sa_make_ready(sai, entry, rc);
 698 }
 699
 700 /* once there are async stat replies, instantiate sa_entry from replies */
 701 static void sa_handle_callback(struct ll_statahead_info *sai)
 702 {
 703         struct ll_inode_info *lli;
 704
 705         lli = ll_i2info(sai->sai_dentry->d_inode);
 706
 707         spin_lock(&lli->lli_sa_lock);
 708         while (sa_has_callback(sai)) {
 709                 struct sa_entry *entry;
 710
 711                 entry = list_entry(sai->sai_interim_entries.next,
 712                                    struct sa_entry, se_list);
 713                 list_del_init(&entry->se_list);
 714                 spin_unlock(&lli->lli_sa_lock);
 715
 716                 sa_instantiate(sai, entry);
 717                 spin_lock(&lli->lli_sa_lock);
 718         }
 719         spin_unlock(&lli->lli_sa_lock);
 720 }
 721
 722 /*
 723  * callback for async stat RPC, because this is called in ptlrpcd context, we
 724  * only put sa_entry in sai_interim_entries, and wake up statahead thread to
 725  * really prepare inode and instantiate sa_entry later.
 726  */
 727 static int ll_statahead_interpret(struct ptlrpc_request *req,
 728                                   struct md_enqueue_info *minfo, int rc)
 729 {
 730         struct lookup_intent *it = &minfo->mi_it;
 731         struct inode *dir = minfo->mi_dir;
 732         struct ll_inode_info *lli = ll_i2info(dir);
 733         struct ll_statahead_info *sai = lli->lli_sai;
 734         struct sa_entry *entry = (struct sa_entry *)minfo->mi_cbdata;
 735         __u64 handle = 0;
 736
 737         ENTRY;
 738
 739         if (it_disposition(it, DISP_LOOKUP_NEG))
 740                 rc = -ENOENT;
 741
 742         /*
 743          * because statahead thread will wait for all inflight RPC to finish,
 744          * sai should be always valid, no need to refcount
 745          */
 746         LASSERT(sai != NULL);
 747         LASSERT(entry != NULL);
 748
 749         CDEBUG(D_READA, "sa_entry %.*s rc %d\n",
 750                entry->se_qstr.len, entry->se_qstr.name, rc);
 751
 752         if (rc != 0) {
 753                 ll_intent_release(it);
 754                 sa_fini_data(minfo);
 755         } else {
 756                 /*
 757                  * release ibits lock ASAP to avoid deadlock when statahead
 758                  * thread enqueues lock on parent in readdir and another
 759                  * process enqueues lock on child with parent lock held, eg.
 760                  * unlink.
 761                  */
 762                 handle = it->it_lock_handle;
 763                 ll_intent_drop_lock(it);
 764                 ll_unlock_md_op_lsm(&minfo->mi_data);
 765         }
 766
 767         spin_lock(&lli->lli_sa_lock);
 768         if (rc != 0) {
 769                 if (__sa_make_ready(sai, entry, rc))
 770                         wake_up(&sai->sai_waitq);
 771         } else {
 772                 int first = 0;
 773
 774                 entry->se_minfo = minfo;
 775                 entry->se_req = ptlrpc_request_addref(req);
 776                 /*
 777                  * Release the async ibits lock ASAP to avoid deadlock
 778                  * when statahead thread tries to enqueue lock on parent
 779                  * for readpage and other tries to enqueue lock on child
 780                  * with parent's lock held, for example: unlink.
 781                  */
 782                 entry->se_handle = handle;
 783                 if (!sa_has_callback(sai))
 784                         first = 1;
 785
 786                 list_add_tail(&entry->se_list, &sai->sai_interim_entries);
 787                 if (first && sai->sai_task)
 788                         wake_up_process(sai->sai_task);
 789         }
 790         sai->sai_replied++;
 791
 792         spin_unlock(&lli->lli_sa_lock);
 793
 794         RETURN(rc);
 795 }
 796
 797 /* async stat for file not found in dcache */
 798 static int sa_lookup(struct inode *dir, struct sa_entry *entry)
 799 {
 800         struct md_enqueue_info   *minfo;
 801         int                       rc;
 802
 803         ENTRY;
 804
 805         minfo = sa_prep_data(dir, NULL, entry);
 806         if (IS_ERR(minfo))
 807                 RETURN(PTR_ERR(minfo));
 808
 809         rc = md_intent_getattr_async(ll_i2mdexp(dir), minfo);
 810         if (rc < 0)
 811                 sa_fini_data(minfo);
 812
 813         RETURN(rc);
 814 }
 815
 816 /**
 817  * async stat for file found in dcache, similar to .revalidate
 818  *
 819  * \retval      1 dentry valid, no RPC sent
 820  * \retval      0 dentry invalid, will send async stat RPC
 821  * \retval      negative number upon error
 822  */
 823 static int sa_revalidate(struct inode *dir, struct sa_entry *entry,
 824                          struct dentry *dentry)
 825 {
 826         struct inode *inode = dentry->d_inode;
 827         struct lookup_intent it = { .it_op = IT_GETATTR,
 828                                     .it_lock_handle = 0 };
 829         struct md_enqueue_info *minfo;
 830         int rc;
 831
 832         ENTRY;
 833
 834         if (unlikely(!inode))
 835                 RETURN(1);
 836
 837         if (d_mountpoint(dentry))
 838                 RETURN(1);
 839
 840         minfo = sa_prep_data(dir, inode, entry);
 841         if (IS_ERR(minfo))
 842                 RETURN(PTR_ERR(minfo));
 843
 844         entry->se_inode = igrab(inode);
 845         rc = md_revalidate_lock(ll_i2mdexp(dir), &it, ll_inode2fid(inode),
 846                                 NULL);
 847         if (rc == 1) {
 848                 entry->se_handle = it.it_lock_handle;
 849                 ll_intent_release(&it);
 850                 sa_fini_data(minfo);
 851                 RETURN(1);
 852         }
 853
 854         rc = md_intent_getattr_async(ll_i2mdexp(dir), minfo);
 855         if (rc < 0) {
 856                 entry->se_inode = NULL;
 857                 iput(inode);
 858                 sa_fini_data(minfo);
 859         }
 860
 861         RETURN(rc);
 862 }
 863
 864 /* async stat for file with @name */
 865 static void sa_statahead(struct dentry *parent, const char *name, int len,
 866                          const struct lu_fid *fid)
 867 {
 868         struct inode *dir = parent->d_inode;
 869         struct ll_inode_info *lli = ll_i2info(dir);
 870         struct ll_statahead_info *sai = lli->lli_sai;
 871         struct dentry *dentry = NULL;
 872         struct sa_entry *entry;
 873         int rc;
 874
 875         ENTRY;
 876
 877         entry = sa_alloc(parent, sai, sai->sai_index, name, len, fid);
 878         if (IS_ERR(entry))
 879                 RETURN_EXIT;
 880
 881         dentry = d_lookup(parent, &entry->se_qstr);
 882         if (!dentry) {
 883                 rc = sa_lookup(dir, entry);
 884         } else {
 885                 rc = sa_revalidate(dir, entry, dentry);
 886                 if (rc == 1 && agl_should_run(sai, dentry->d_inode))
 887                         ll_agl_add(sai, dentry->d_inode, entry->se_index);
 888         }
 889
 890         if (dentry)
 891                 dput(dentry);
 892
 893         if (rc != 0)
 894                 sa_make_ready(sai, entry, rc);
 895         else
 896                 sai->sai_sent++;
 897
 898         sai->sai_index++;
 899
 900         EXIT;
 901 }
 902
 903 /* async glimpse (agl) thread main function */
 904 static int ll_agl_thread(void *arg)
 905 {
 906         struct dentry *parent = (struct dentry *)arg;
 907         struct inode *dir = parent->d_inode;
 908         struct ll_inode_info *plli = ll_i2info(dir);
 909         struct ll_inode_info *clli;
 910         /*
 911          * We already own this reference, so it is safe to take it
 912          * without a lock.
 913          */
 914         struct ll_statahead_info *sai = plli->lli_sai;
 915
 916         ENTRY;
 917
 918         CDEBUG(D_READA, "agl thread started: sai %p, parent %pd\n",
 919                sai, parent);
 920
 921         while (({set_current_state(TASK_IDLE);
 922                  !kthread_should_stop(); })) {
 923                 spin_lock(&plli->lli_agl_lock);
 924                 if (!agl_list_empty(sai)) {
 925                         __set_current_state(TASK_RUNNING);
 926                         clli = agl_first_entry(sai);
 927                         list_del_init(&clli->lli_agl_list);
 928                         spin_unlock(&plli->lli_agl_lock);
 929                         ll_agl_trigger(&clli->lli_vfs_inode, sai);
 930                         cond_resched();
 931                 } else {
 932                         spin_unlock(&plli->lli_agl_lock);
 933                         schedule();
 934                 }
 935         }
 936         __set_current_state(TASK_RUNNING);
 937         RETURN(0);
 938 }
 939
 940 static void ll_stop_agl(struct ll_statahead_info *sai)
 941 {
 942         struct dentry *parent = sai->sai_dentry;
 943         struct ll_inode_info *plli = ll_i2info(parent->d_inode);
 944         struct ll_inode_info *clli;
 945         struct task_struct *agl_task;
 946
 947         spin_lock(&plli->lli_agl_lock);
 948         agl_task = sai->sai_agl_task;
 949         sai->sai_agl_task = NULL;
 950         spin_unlock(&plli->lli_agl_lock);
 951         if (!agl_task)
 952                 return;
 953
 954         CDEBUG(D_READA, "stop agl thread: sai %p pid %u\n",
 955                sai, (unsigned int)agl_task->pid);
 956         kthread_stop(agl_task);
 957
 958         spin_lock(&plli->lli_agl_lock);
 959         while (!agl_list_empty(sai)) {
 960                 clli = agl_first_entry(sai);
 961                 list_del_init(&clli->lli_agl_list);
 962                 spin_unlock(&plli->lli_agl_lock);
 963                 clli->lli_agl_index = 0;
 964                 iput(&clli->lli_vfs_inode);
 965                 spin_lock(&plli->lli_agl_lock);
 966         }
 967         spin_unlock(&plli->lli_agl_lock);
 968         CDEBUG(D_READA, "agl thread stopped: sai %p, parent %pd\n",
 969                sai, parent);
 970         ll_sai_put(sai);
 971 }
 972
 973 /* start agl thread */
 974 static void ll_start_agl(struct dentry *parent, struct ll_statahead_info *sai)
 975 {
 976         int node = cfs_cpt_spread_node(cfs_cpt_tab, CFS_CPT_ANY);
 977         struct ll_inode_info *plli;
 978         struct task_struct *task;
 979
 980         ENTRY;
 981
 982         CDEBUG(D_READA, "start agl thread: sai %p, parent %pd\n",
 983                sai, parent);
 984
 985         plli = ll_i2info(parent->d_inode);
 986         task = kthread_create_on_node(ll_agl_thread, parent, node, "ll_agl_%d",
 987                                       plli->lli_opendir_pid);
 988         if (IS_ERR(task)) {
 989                 CERROR("can't start ll_agl thread, rc: %ld\n", PTR_ERR(task));
 990                 RETURN_EXIT;
 991         }
 992         sai->sai_agl_task = task;
 993         atomic_inc(&ll_i2sbi(d_inode(parent))->ll_agl_total);
 994         /* Get an extra reference that the thread holds */
 995         ll_sai_get(d_inode(parent));
 996
 997         wake_up_process(task);
 998
 999         EXIT;
1000 }
1001
1002 /* statahead thread main function */
1003 static int ll_statahead_thread(void *arg)
1004 {
1005         struct dentry *parent = (struct dentry *)arg;
1006         struct inode *dir = parent->d_inode;
1007         struct ll_inode_info *lli = ll_i2info(dir);
1008         struct ll_sb_info *sbi = ll_i2sbi(dir);
1009         struct ll_statahead_info *sai = lli->lli_sai;
1010         int first = 0;
1011         struct md_op_data *op_data;
1012         struct page *page = NULL;
1013         __u64 pos = 0;
1014         int rc = 0;
1015
1016         ENTRY;
1017
1018         CDEBUG(D_READA, "statahead thread starting: sai %p, parent %pd\n",
1019                sai, parent);
1020
1021         OBD_ALLOC_PTR(op_data);
1022         if (!op_data)
1023                 GOTO(out, rc = -ENOMEM);
1024
1025         while (pos != MDS_DIR_END_OFF && sai->sai_task) {
1026                 struct lu_dirpage *dp;
1027                 struct lu_dirent  *ent;
1028
1029                 op_data = ll_prep_md_op_data(op_data, dir, dir, NULL, 0, 0,
1030                                              LUSTRE_OPC_ANY, dir);
1031                 if (IS_ERR(op_data)) {
1032                         rc = PTR_ERR(op_data);
1033                         break;
1034                 }
1035
1036                 sai->sai_in_readpage = 1;
1037                 page = ll_get_dir_page(dir, op_data, pos);
1038                 ll_unlock_md_op_lsm(op_data);
1039                 sai->sai_in_readpage = 0;
1040                 if (IS_ERR(page)) {
1041                         rc = PTR_ERR(page);
1042                         CDEBUG(D_READA,
1043                                "error reading dir "DFID" at %llu /%llu opendir_pid = %u: rc = %d\n",
1044                                PFID(ll_inode2fid(dir)), pos, sai->sai_index,
1045                                lli->lli_opendir_pid, rc);
1046                         break;
1047                 }
1048
1049                 dp = page_address(page);
1050                 for (ent = lu_dirent_start(dp);
1051                      ent != NULL && sai->sai_task &&
1052                      !sa_low_hit(sai);
1053                      ent = lu_dirent_next(ent)) {
1054                         __u64 hash;
1055                         int namelen;
1056                         char *name;
1057                         struct lu_fid fid;
1058
1059                         hash = le64_to_cpu(ent->lde_hash);
1060                         if (unlikely(hash < pos))
1061                                 /*
1062                                  * Skip until we find target hash value.
1063                                  */
1064                                 continue;
1065
1066                         namelen = le16_to_cpu(ent->lde_namelen);
1067                         if (unlikely(namelen == 0))
1068                                 /*
1069                                  * Skip dummy record.
1070                                  */
1071                                 continue;
1072
1073                         name = ent->lde_name;
1074                         if (name[0] == '.') {
1075                                 if (namelen == 1) {
1076                                         /*
1077                                          * skip "."
1078                                          */
1079                                         continue;
1080                                 } else if (name[1] == '.' && namelen == 2) {
1081                                         /*
1082                                          * skip ".."
1083                                          */
1084                                         continue;
1085                                 } else if (!sai->sai_ls_all) {
1086                                         /*
1087                                          * skip hidden files.
1088                                          */
1089                                         sai->sai_skip_hidden++;
1090                                         continue;
1091                                 }
1092                         }
1093
1094                         /*
1095                          * don't stat-ahead first entry.
1096                          */
1097                         if (unlikely(++first == 1))
1098                                 continue;
1099
1100                         fid_le_to_cpu(&fid, &ent->lde_fid);
1101
1102                         while (({set_current_state(TASK_IDLE);
1103                                  sai->sai_task; })) {
1104                                 if (sa_has_callback(sai)) {
1105                                         __set_current_state(TASK_RUNNING);
1106                                         sa_handle_callback(sai);
1107                                 }
1108
1109                                 spin_lock(&lli->lli_agl_lock);
1110                                 while (sa_sent_full(sai) &&
1111                                        !agl_list_empty(sai)) {
1112                                         struct ll_inode_info *clli;
1113
1114                                         __set_current_state(TASK_RUNNING);
1115                                         clli = agl_first_entry(sai);
1116                                         list_del_init(&clli->lli_agl_list);
1117                                         spin_unlock(&lli->lli_agl_lock);
1118
1119                                         ll_agl_trigger(&clli->lli_vfs_inode,
1120                                                        sai);
1121                                         cond_resched();
1122                                         spin_lock(&lli->lli_agl_lock);
1123                                 }
1124                                 spin_unlock(&lli->lli_agl_lock);
1125
1126                                 if (!sa_sent_full(sai))
1127                                         break;
1128                                 schedule();
1129                         }
1130                         __set_current_state(TASK_RUNNING);
1131
1132                         sa_statahead(parent, name, namelen, &fid);
1133                 }
1134
1135                 pos = le64_to_cpu(dp->ldp_hash_end);
1136                 ll_release_page(dir, page,
1137                                 le32_to_cpu(dp->ldp_flags) & LDF_COLLIDE);
1138
1139                 if (sa_low_hit(sai)) {
1140                         rc = -EFAULT;
1141                         atomic_inc(&sbi->ll_sa_wrong);
1142                         CDEBUG(D_READA,
1143                                "Statahead for dir "DFID" hit ratio too low: hit/miss %llu/%llu, sent/replied %llu/%llu, stoppingstatahead thread: pid %d\n",
1144                                PFID(&lli->lli_fid), sai->sai_hit,
1145                                sai->sai_miss, sai->sai_sent,
1146                                sai->sai_replied, current->pid);
1147                         break;
1148                 }
1149         }
1150         ll_finish_md_op_data(op_data);
1151
1152         if (rc < 0) {
1153                 spin_lock(&lli->lli_sa_lock);
1154                 sai->sai_task = NULL;
1155                 lli->lli_sa_enabled = 0;
1156                 spin_unlock(&lli->lli_sa_lock);
1157         }
1158
1159         /*
1160          * statahead is finished, but statahead entries need to be cached, wait
1161          * for file release to stop me.
1162          */
1163         while (({set_current_state(TASK_IDLE);
1164                  sai->sai_task; })) {
1165                 if (sa_has_callback(sai)) {
1166                         __set_current_state(TASK_RUNNING);
1167                         sa_handle_callback(sai);
1168                 } else {
1169                         schedule();
1170                 }
1171         }
1172         __set_current_state(TASK_RUNNING);
1173
1174         EXIT;
1175 out:
1176         ll_stop_agl(sai);
1177
1178         /*
1179          * wait for inflight statahead RPCs to finish, and then we can free sai
1180          * safely because statahead RPC will access sai data
1181          */
1182         while (sai->sai_sent != sai->sai_replied)
1183                 /* in case we're not woken up, timeout wait */
1184                 msleep(125);
1185
1186         /* release resources held by statahead RPCs */
1187         sa_handle_callback(sai);
1188
1189         CDEBUG(D_READA, "%s: statahead thread stopped: sai %p, parent %pd\n",
1190                sbi->ll_fsname, sai, parent);
1191
1192         spin_lock(&lli->lli_sa_lock);
1193         sai->sai_task = NULL;
1194         spin_unlock(&lli->lli_sa_lock);
1195         wake_up(&sai->sai_waitq);
1196
1197         ll_sai_put(sai);
1198
1199         return rc;
1200 }
1201
1202 /* authorize opened dir handle @key to statahead */
1203 void ll_authorize_statahead(struct inode *dir, void *key)
1204 {
1205         struct ll_inode_info *lli = ll_i2info(dir);
1206
1207         spin_lock(&lli->lli_sa_lock);
1208         if (!lli->lli_opendir_key && !lli->lli_sai) {
1209                 /*
1210                  * if lli_sai is not NULL, it means previous statahead is not
1211                  * finished yet, we'd better not start a new statahead for now.
1212                  */
1213                 LASSERT(lli->lli_opendir_pid == 0);
1214                 lli->lli_opendir_key = key;
1215                 lli->lli_opendir_pid = current->pid;
1216                 lli->lli_sa_enabled = 1;
1217         }
1218         spin_unlock(&lli->lli_sa_lock);
1219 }
1220
1221 /*
1222  * deauthorize opened dir handle @key to statahead, and notify statahead thread
1223  * to quit if it's running.
1224  */
1225 void ll_deauthorize_statahead(struct inode *dir, void *key)
1226 {
1227         struct ll_inode_info *lli = ll_i2info(dir);
1228         struct ll_statahead_info *sai;
1229
1230         LASSERT(lli->lli_opendir_key == key);
1231         LASSERT(lli->lli_opendir_pid != 0);
1232
1233         CDEBUG(D_READA, "deauthorize statahead for "DFID"\n",
1234                PFID(&lli->lli_fid));
1235
1236         spin_lock(&lli->lli_sa_lock);
1237         lli->lli_opendir_key = NULL;
1238         lli->lli_opendir_pid = 0;
1239         lli->lli_sa_enabled = 0;
1240         sai = lli->lli_sai;
1241         if (sai && sai->sai_task) {
1242                 /*
1243                  * statahead thread may not have quit yet because it needs to
1244                  * cache entries, now it's time to tell it to quit.
1245                  *
1246                  * wake_up_process() provides the necessary barriers
1247                  * to pair with set_current_state().
1248                  */
1249                 struct task_struct *task = sai->sai_task;
1250
1251                 sai->sai_task = NULL;
1252                 wake_up_process(task);
1253         }
1254         spin_unlock(&lli->lli_sa_lock);
1255 }
1256
1257 enum {
1258         /**
1259          * not first dirent, or is "."
1260          */
1261         LS_NOT_FIRST_DE = 0,
1262         /**
1263          * the first non-hidden dirent
1264          */
1265         LS_FIRST_DE,
1266         /**
1267          * the first hidden dirent, that is "."
1268          */
1269         LS_FIRST_DOT_DE
1270 };
1271
1272 /* file is first dirent under @dir */
1273 static int is_first_dirent(struct inode *dir, struct dentry *dentry)
1274 {
1275         struct qstr          *target = &dentry->d_name;
1276         struct md_op_data    *op_data;
1277         int                   dot_de;
1278         struct page          *page = NULL;
1279         int                   rc = LS_NOT_FIRST_DE;
1280         __u64                 pos = 0;
1281
1282         ENTRY;
1283
1284         op_data = ll_prep_md_op_data(NULL, dir, dir, NULL, 0, 0,
1285                                      LUSTRE_OPC_ANY, dir);
1286         if (IS_ERR(op_data))
1287                 RETURN(PTR_ERR(op_data));
1288         /**
1289          *FIXME choose the start offset of the readdir
1290          */
1291
1292         page = ll_get_dir_page(dir, op_data, 0);
1293
1294         while (1) {
1295                 struct lu_dirpage *dp;
1296                 struct lu_dirent  *ent;
1297
1298                 if (IS_ERR(page)) {
1299                         struct ll_inode_info *lli = ll_i2info(dir);
1300
1301                         rc = PTR_ERR(page);
1302                         CERROR("%s: reading dir "DFID" at %llu opendir_pid = %u : rc = %d\n",
1303                                ll_i2sbi(dir)->ll_fsname,
1304                                PFID(ll_inode2fid(dir)), pos,
1305                                lli->lli_opendir_pid, rc);
1306                         break;
1307                 }
1308
1309                 dp = page_address(page);
1310                 for (ent = lu_dirent_start(dp); ent != NULL;
1311                      ent = lu_dirent_next(ent)) {
1312                         __u64 hash;
1313                         int namelen;
1314                         char *name;
1315
1316                         hash = le64_to_cpu(ent->lde_hash);
1317                         /*
1318                          * The ll_get_dir_page() can return any page containing
1319                          * the given hash which may be not the start hash.
1320                          */
1321                         if (unlikely(hash < pos))
1322                                 continue;
1323
1324                         namelen = le16_to_cpu(ent->lde_namelen);
1325                         if (unlikely(namelen == 0))
1326                                 /*
1327                                  * skip dummy record.
1328                                  */
1329                                 continue;
1330
1331                         name = ent->lde_name;
1332                         if (name[0] == '.') {
1333                                 if (namelen == 1)
1334                                         /*
1335                                          * skip "."
1336                                          */
1337                                         continue;
1338                                 else if (name[1] == '.' && namelen == 2)
1339                                         /*
1340                                          * skip ".."
1341                                          */
1342                                         continue;
1343                                 else
1344                                         dot_de = 1;
1345                         } else {
1346                                 dot_de = 0;
1347                         }
1348
1349                         if (dot_de && target->name[0] != '.') {
1350                                 CDEBUG(D_READA, "%.*s skip hidden file %.*s\n",
1351                                        target->len, target->name,
1352                                        namelen, name);
1353                                 continue;
1354                         }
1355
1356                         if (target->len != namelen ||
1357                             memcmp(target->name, name, namelen) != 0)
1358                                 rc = LS_NOT_FIRST_DE;
1359                         else if (!dot_de)
1360                                 rc = LS_FIRST_DE;
1361                         else
1362                                 rc = LS_FIRST_DOT_DE;
1363
1364                         ll_release_page(dir, page, false);
1365                         GOTO(out, rc);
1366                 }
1367                 pos = le64_to_cpu(dp->ldp_hash_end);
1368                 if (pos == MDS_DIR_END_OFF) {
1369                         /*
1370                          * End of directory reached.
1371                          */
1372                         ll_release_page(dir, page, false);
1373                         GOTO(out, rc);
1374                 } else {
1375                         /*
1376                          * chain is exhausted
1377                          * Normal case: continue to the next page.
1378                          */
1379                         ll_release_page(dir, page, le32_to_cpu(dp->ldp_flags) &
1380                                               LDF_COLLIDE);
1381                         page = ll_get_dir_page(dir, op_data, pos);
1382                 }
1383         }
1384         EXIT;
1385 out:
1386         ll_finish_md_op_data(op_data);
1387
1388         return rc;
1389 }
1390
1391 /**
1392  * revalidate @dentryp from statahead cache
1393  *
1394  * \param[in] dir       parent directory
1395  * \param[in] sai       sai structure
1396  * \param[out] dentryp  pointer to dentry which will be revalidated
1397  * \param[in] unplug    unplug statahead window only (normally for negative
1398  *                      dentry)
1399  * \retval              1 on success, dentry is saved in @dentryp
1400  * \retval              0 if revalidation failed (no proper lock on client)
1401  * \retval              negative number upon error
1402  */
1403 static int revalidate_statahead_dentry(struct inode *dir,
1404                                        struct ll_statahead_info *sai,
1405                                        struct dentry **dentryp,
1406                                        bool unplug)
1407 {
1408         struct sa_entry *entry = NULL;
1409         struct ll_dentry_data *ldd;
1410         struct ll_inode_info *lli = ll_i2info(dir);
1411         int rc = 0;
1412
1413         ENTRY;
1414
1415         if ((*dentryp)->d_name.name[0] == '.') {
1416                 if (sai->sai_ls_all ||
1417                     sai->sai_miss_hidden >= sai->sai_skip_hidden) {
1418                         /*
1419                          * Hidden dentry is the first one, or statahead
1420                          * thread does not skip so many hidden dentries
1421                          * before "sai_ls_all" enabled as below.
1422                          */
1423                 } else {
1424                         if (!sai->sai_ls_all)
1425                                 /*
1426                                  * It maybe because hidden dentry is not
1427                                  * the first one, "sai_ls_all" was not
1428                                  * set, then "ls -al" missed. Enable
1429                                  * "sai_ls_all" for such case.
1430                                  */
1431                                 sai->sai_ls_all = 1;
1432
1433                         /*
1434                          * Such "getattr" has been skipped before
1435                          * "sai_ls_all" enabled as above.
1436                          */
1437                         sai->sai_miss_hidden++;
1438                         RETURN(-EAGAIN);
1439                 }
1440         }
1441
1442         if (unplug)
1443                 GOTO(out, rc = 1);
1444
1445         entry = sa_get(sai, &(*dentryp)->d_name);
1446         if (!entry)
1447                 GOTO(out, rc = -EAGAIN);
1448
1449         /* if statahead is busy in readdir, help it do post-work */
1450         if (!sa_ready(entry) && sai->sai_in_readpage)
1451                 sa_handle_callback(sai);
1452
1453         if (!sa_ready(entry)) {
1454                 spin_lock(&lli->lli_sa_lock);
1455                 sai->sai_index_wait = entry->se_index;
1456                 spin_unlock(&lli->lli_sa_lock);
1457                 rc = wait_event_idle_timeout(sai->sai_waitq, sa_ready(entry),
1458                                              cfs_time_seconds(30));
1459                 if (rc == 0) {
1460                         /*
1461                          * entry may not be ready, so it may be used by inflight
1462                          * statahead RPC, don't free it.
1463                          */
1464                         entry = NULL;
1465                         GOTO(out, rc = -EAGAIN);
1466                 }
1467         }
1468
1469         /*
1470          * We need to see the value that was set immediately before we
1471          * were woken up.
1472          */
1473         if (smp_load_acquire(&entry->se_state) == SA_ENTRY_SUCC &&
1474             entry->se_inode) {
1475                 struct inode *inode = entry->se_inode;
1476                 struct lookup_intent it = { .it_op = IT_GETATTR,
1477                                             .it_lock_handle =
1478                                                 entry->se_handle };
1479                 __u64 bits;
1480
1481                 rc = md_revalidate_lock(ll_i2mdexp(dir), &it,
1482                                         ll_inode2fid(inode), &bits);
1483                 if (rc == 1) {
1484                         if (!(*dentryp)->d_inode) {
1485                                 struct dentry *alias;
1486
1487                                 alias = ll_splice_alias(inode, *dentryp);
1488                                 if (IS_ERR(alias)) {
1489                                         ll_intent_release(&it);
1490                                         GOTO(out, rc = PTR_ERR(alias));
1491                                 }
1492                                 *dentryp = alias;
1493                                 /*
1494                                  * statahead prepared this inode, transfer inode
1495                                  * refcount from sa_entry to dentry
1496                                  */
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 %pd inode " DFID", statahead inode "DFID "\n",
1502                                        ll_i2sbi(inode)->ll_fsname, *dentryp,
1503                                        PFID(ll_inode2fid((*dentryp)->d_inode)),
1504                                        PFID(ll_inode2fid(inode)));
1505                                 ll_intent_release(&it);
1506                                 GOTO(out, rc = -ESTALE);
1507                         }
1508
1509                         if ((bits & MDS_INODELOCK_LOOKUP) &&
1510                             d_lustre_invalid(*dentryp))
1511                                 d_lustre_revalidate(*dentryp);
1512                         ll_intent_release(&it);
1513                 }
1514         }
1515 out:
1516         /*
1517          * statahead cached sa_entry can be used only once, and will be killed
1518          * right after use, so if lookup/revalidate accessed statahead cache,
1519          * set dentry ldd_sa_generation to parent lli_sa_generation, later if we
1520          * stat this file again, we know we've done statahead before, see
1521          * dentry_may_statahead().
1522          */
1523         ldd = ll_d2d(*dentryp);
1524         /* ldd can be NULL if llite lookup failed. */
1525         if (ldd)
1526                 ldd->lld_sa_generation = lli->lli_sa_generation;
1527         sa_put(sai, entry);
1528         spin_lock(&lli->lli_sa_lock);
1529         if (sai->sai_task)
1530                 wake_up_process(sai->sai_task);
1531         spin_unlock(&lli->lli_sa_lock);
1532
1533         RETURN(rc);
1534 }
1535
1536 /**
1537  * start statahead thread
1538  *
1539  * \param[in] dir       parent directory
1540  * \param[in] dentry    dentry that triggers statahead, normally the first
1541  *                      dirent under @dir
1542  * \param[in] agl       indicate whether AGL is needed
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                                   bool agl)
1551 {
1552         int node = cfs_cpt_spread_node(cfs_cpt_tab, CFS_CPT_ANY);
1553         struct ll_inode_info *lli = ll_i2info(dir);
1554         struct ll_statahead_info *sai = NULL;
1555         struct dentry *parent = dentry->d_parent;
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
1561         ENTRY;
1562
1563         /* I am the "lli_opendir_pid" owner, only me can set "lli_sai". */
1564         first = is_first_dirent(dir, dentry);
1565         if (first == LS_NOT_FIRST_DE)
1566                 /* It is not "ls -{a}l" operation, no need statahead for it. */
1567                 GOTO(out, rc = -EFAULT);
1568
1569         if (unlikely(atomic_inc_return(&sbi->ll_sa_running) >
1570                                        sbi->ll_sa_running_max)) {
1571                 CDEBUG(D_READA,
1572                        "Too many concurrent statahead instances, avoid new statahead instance temporarily.\n");
1573                 GOTO(out, rc = -EMFILE);
1574         }
1575
1576         sai = ll_sai_alloc(parent);
1577         if (!sai)
1578                 GOTO(out, rc = -ENOMEM);
1579
1580         sai->sai_ls_all = (first == LS_FIRST_DOT_DE);
1581
1582         /*
1583          * if current lli_opendir_key was deauthorized, or dir re-opened by
1584          * another process, don't start statahead, otherwise the newly spawned
1585          * statahead thread won't be notified to quit.
1586          */
1587         spin_lock(&lli->lli_sa_lock);
1588         if (unlikely(lli->lli_sai || !lli->lli_opendir_key ||
1589                      lli->lli_opendir_pid != current->pid)) {
1590                 spin_unlock(&lli->lli_sa_lock);
1591                 GOTO(out, rc = -EPERM);
1592         }
1593         lli->lli_sai = sai;
1594         spin_unlock(&lli->lli_sa_lock);
1595
1596         CDEBUG(D_READA, "start statahead thread: [pid %d] [parent %pd]\n",
1597                current->pid, parent);
1598
1599         task = kthread_create_on_node(ll_statahead_thread, parent, node,
1600                                       "ll_sa_%u", lli->lli_opendir_pid);
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         if (ll_i2sbi(parent->d_inode)->ll_flags & LL_SBI_AGL_ENABLED && agl)
1611                 ll_start_agl(parent, sai);
1612
1613         atomic_inc(&ll_i2sbi(parent->d_inode)->ll_sa_total);
1614         sai->sai_task = task;
1615
1616         wake_up_process(task);
1617         /*
1618          * We don't stat-ahead for the first dirent since we are already in
1619          * lookup.
1620          */
1621         RETURN(-EAGAIN);
1622
1623 out:
1624         /*
1625          * once we start statahead thread failed, disable statahead so that
1626          * subsequent stat won't waste time to try it.
1627          */
1628         spin_lock(&lli->lli_sa_lock);
1629         if (lli->lli_opendir_pid == current->pid)
1630                 lli->lli_sa_enabled = 0;
1631         spin_unlock(&lli->lli_sa_lock);
1632
1633         if (sai)
1634                 ll_sai_free(sai);
1635         if (first != LS_NOT_FIRST_DE)
1636                 atomic_dec(&sbi->ll_sa_running);
1637
1638         RETURN(rc);
1639 }
1640
1641 /*
1642  * Check whether statahead for @dir was started.
1643  */
1644 static inline bool ll_statahead_started(struct inode *dir, bool agl)
1645 {
1646         struct ll_inode_info *lli = ll_i2info(dir);
1647         struct ll_statahead_info *sai;
1648
1649         spin_lock(&lli->lli_sa_lock);
1650         sai = lli->lli_sai;
1651         if (sai && (sai->sai_agl_task != NULL) != agl)
1652                 CDEBUG(D_READA,
1653                        "%s: Statahead AGL hint changed from %d to %d\n",
1654                        ll_i2sbi(dir)->ll_fsname,
1655                        sai->sai_agl_task != NULL, agl);
1656         spin_unlock(&lli->lli_sa_lock);
1657
1658         return !!sai;
1659 }
1660
1661 /**
1662  * statahead entry function, this is called when client getattr on a file, it
1663  * will start statahead thread if this is the first dir entry, else revalidate
1664  * dentry from statahead cache.
1665  *
1666  * \param[in]  dir      parent directory
1667  * \param[out] dentryp  dentry to getattr
1668  * \param[in]  agl      whether start the agl thread
1669  *
1670  * \retval              1 on success
1671  * \retval              0 revalidation from statahead cache failed, caller needs
1672  *                      to getattr from server directly
1673  * \retval              negative number on error, caller often ignores this and
1674  *                      then getattr from server
1675  */
1676 int ll_start_statahead(struct inode *dir, struct dentry *dentry, bool agl)
1677 {
1678         if (!ll_statahead_started(dir, agl))
1679                 return start_statahead_thread(dir, dentry, agl);
1680         return 0;
1681 }
1682
1683 /**
1684  * revalidate dentry from statahead cache.
1685  *
1686  * \param[in]  dir      parent directory
1687  * \param[out] dentryp  dentry to getattr
1688  * \param[in]  unplug   unplug statahead window only (normally for negative
1689  *                      dentry)
1690  * \retval              1 on success
1691  * \retval              0 revalidation from statahead cache failed, caller needs
1692  *                      to getattr from server directly
1693  * \retval              negative number on error, caller often ignores this and
1694  *                      then getattr from server
1695  */
1696 int ll_revalidate_statahead(struct inode *dir, struct dentry **dentryp,
1697                             bool unplug)
1698 {
1699         struct ll_statahead_info *sai;
1700         int rc = 0;
1701
1702         sai = ll_sai_get(dir);
1703         if (sai) {
1704                 rc = revalidate_statahead_dentry(dir, sai, dentryp, unplug);
1705                 CDEBUG(D_READA, "revalidate statahead %pd: rc = %d.\n",
1706                        *dentryp, rc);
1707                 ll_sai_put(sai);
1708         }
1709         return rc;
1710 }