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, 2016, 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         int rc;
 498         ENTRY;
 499
 500         LASSERT(list_empty(&lli->lli_agl_list));
 501
 502         /* AGL maybe fall behind statahead with one entry */
 503         if (is_omitted_entry(sai, index + 1)) {
 504                 lli->lli_agl_index = 0;
 505                 iput(inode);
 506                 RETURN_EXIT;
 507         }
 508
 509         /* In case of restore, the MDT has the right size and has already
 510          * sent it back without granting the layout lock, inode is up-to-date.
 511          * Then AGL (async glimpse lock) is useless.
 512          * Also to glimpse we need the layout, in case of a runninh restore
 513          * the MDT holds the layout lock so the glimpse will block up to the
 514          * end of restore (statahead/agl will block) */
 515         if (ll_file_test_flag(lli, LLIF_FILE_RESTORING)) {
 516                 lli->lli_agl_index = 0;
 517                 iput(inode);
 518                 RETURN_EXIT;
 519         }
 520
 521         /* Someone is in glimpse (sync or async), do nothing. */
 522         rc = down_write_trylock(&lli->lli_glimpse_sem);
 523         if (rc == 0) {
 524                 lli->lli_agl_index = 0;
 525                 iput(inode);
 526                 RETURN_EXIT;
 527         }
 528
 529         /*
 530          * Someone triggered glimpse within 1 sec before.
 531          * 1) The former glimpse succeeded with glimpse lock granted by OST, and
 532          *    if the lock is still cached on client, AGL needs to do nothing. If
 533          *    it is cancelled by other client, AGL maybe cannot obtaion new lock
 534          *    for no glimpse callback triggered by AGL.
 535          * 2) The former glimpse succeeded, but OST did not grant glimpse lock.
 536          *    Under such case, it is quite possible that the OST will not grant
 537          *    glimpse lock for AGL also.
 538          * 3) The former glimpse failed, compared with other two cases, it is
 539          *    relative rare. AGL can ignore such case, and it will not muchly
 540          *    affect the performance.
 541          */
 542         if (lli->lli_glimpse_time != 0 &&
 543             cfs_time_before(cfs_time_shift(-1), lli->lli_glimpse_time)) {
 544                 up_write(&lli->lli_glimpse_sem);
 545                 lli->lli_agl_index = 0;
 546                 iput(inode);
 547                 RETURN_EXIT;
 548         }
 549
 550         CDEBUG(D_READA, "Handling (init) async glimpse: inode = "
 551                DFID", idx = %llu\n", PFID(&lli->lli_fid), index);
 552
 553         cl_agl(inode);
 554         lli->lli_agl_index = 0;
 555         lli->lli_glimpse_time = cfs_time_current();
 556         up_write(&lli->lli_glimpse_sem);
 557
 558         CDEBUG(D_READA, "Handled (init) async glimpse: inode= "
 559                DFID", idx = %llu, rc = %d\n",
 560                PFID(&lli->lli_fid), index, rc);
 561
 562         iput(inode);
 563
 564         EXIT;
 565 }
 566
 567 /*
 568  * prepare inode for sa entry, add it into agl list, now sa_entry is ready
 569  * to be used by scanner process.
 570  */
 571 static void sa_instantiate(struct ll_statahead_info *sai,
 572                                  struct sa_entry *entry)
 573 {
 574         struct inode *dir = sai->sai_dentry->d_inode;
 575         struct inode *child;
 576         struct md_enqueue_info *minfo;
 577         struct lookup_intent *it;
 578         struct ptlrpc_request *req;
 579         struct mdt_body *body;
 580         int rc = 0;
 581         ENTRY;
 582
 583         LASSERT(entry->se_handle != 0);
 584
 585         minfo = entry->se_minfo;
 586         it = &minfo->mi_it;
 587         req = entry->se_req;
 588         body = req_capsule_server_get(&req->rq_pill, &RMF_MDT_BODY);
 589         if (body == NULL)
 590                 GOTO(out, rc = -EFAULT);
 591
 592         child = entry->se_inode;
 593         if (child != NULL) {
 594                 /* revalidate; unlinked and re-created with the same name */
 595                 if (unlikely(!lu_fid_eq(&minfo->mi_data.op_fid2,
 596                                         &body->mbo_fid1))) {
 597                         entry->se_inode = NULL;
 598                         iput(child);
 599                         child = NULL;
 600                 }
 601         }
 602
 603         it->it_lock_handle = entry->se_handle;
 604         rc = md_revalidate_lock(ll_i2mdexp(dir), it, ll_inode2fid(dir), NULL);
 605         if (rc != 1)
 606                 GOTO(out, rc = -EAGAIN);
 607
 608         rc = ll_prep_inode(&child, req, dir->i_sb, it);
 609         if (rc)
 610                 GOTO(out, rc);
 611
 612         CDEBUG(D_READA, "%s: setting %.*s"DFID" l_data to inode %p\n",
 613                ll_get_fsname(child->i_sb, NULL, 0),
 614                entry->se_qstr.len, entry->se_qstr.name,
 615                PFID(ll_inode2fid(child)), child);
 616         ll_set_lock_data(ll_i2sbi(dir)->ll_md_exp, child, it, NULL);
 617
 618         entry->se_inode = child;
 619
 620         if (agl_should_run(sai, child))
 621                 ll_agl_add(sai, child, entry->se_index);
 622
 623         EXIT;
 624
 625 out:
 626         /* sa_make_ready() will drop ldlm ibits lock refcount by calling
 627          * ll_intent_drop_lock() in spite of failures. Do not worry about
 628          * calling ll_intent_drop_lock() more than once. */
 629         sa_make_ready(sai, entry, rc);
 630 }
 631
 632 /* once there are async stat replies, instantiate sa_entry from replies */
 633 static void sa_handle_callback(struct ll_statahead_info *sai)
 634 {
 635         struct ll_inode_info *lli;
 636
 637         lli = ll_i2info(sai->sai_dentry->d_inode);
 638
 639         while (sa_has_callback(sai)) {
 640                 struct sa_entry *entry;
 641
 642                 spin_lock(&lli->lli_sa_lock);
 643                 if (unlikely(!sa_has_callback(sai))) {
 644                         spin_unlock(&lli->lli_sa_lock);
 645                         break;
 646                 }
 647                 entry = list_entry(sai->sai_interim_entries.next,
 648                                    struct sa_entry, se_list);
 649                 list_del_init(&entry->se_list);
 650                 spin_unlock(&lli->lli_sa_lock);
 651
 652                 sa_instantiate(sai, entry);
 653         }
 654 }
 655
 656 /*
 657  * callback for async stat RPC, because this is called in ptlrpcd context, we
 658  * only put sa_entry in sai_interim_entries, and wake up statahead thread to
 659  * really prepare inode and instantiate sa_entry later.
 660  */
 661 static int ll_statahead_interpret(struct ptlrpc_request *req,
 662                                   struct md_enqueue_info *minfo, int rc)
 663 {
 664         struct lookup_intent *it = &minfo->mi_it;
 665         struct inode *dir = minfo->mi_dir;
 666         struct ll_inode_info *lli = ll_i2info(dir);
 667         struct ll_statahead_info *sai = lli->lli_sai;
 668         struct sa_entry *entry = (struct sa_entry *)minfo->mi_cbdata;
 669         __u64 handle = 0;
 670         wait_queue_head_t *waitq = NULL;
 671         ENTRY;
 672
 673         if (it_disposition(it, DISP_LOOKUP_NEG))
 674                 rc = -ENOENT;
 675
 676         /* because statahead thread will wait for all inflight RPC to finish,
 677          * sai should be always valid, no need to refcount */
 678         LASSERT(sai != NULL);
 679         LASSERT(!thread_is_stopped(&sai->sai_thread));
 680         LASSERT(entry != NULL);
 681
 682         CDEBUG(D_READA, "sa_entry %.*s rc %d\n",
 683                entry->se_qstr.len, entry->se_qstr.name, rc);
 684
 685         if (rc != 0) {
 686                 ll_intent_release(it);
 687                 iput(dir);
 688                 OBD_FREE_PTR(minfo);
 689         } else {
 690                 /* release ibits lock ASAP to avoid deadlock when statahead
 691                  * thread enqueues lock on parent in readdir and another
 692                  * process enqueues lock on child with parent lock held, eg.
 693                  * unlink. */
 694                 handle = it->it_lock_handle;
 695                 ll_intent_drop_lock(it);
 696         }
 697
 698         spin_lock(&lli->lli_sa_lock);
 699         if (rc != 0) {
 700                 if (__sa_make_ready(sai, entry, rc))
 701                         waitq = &sai->sai_waitq;
 702         } else {
 703                 entry->se_minfo = minfo;
 704                 entry->se_req = ptlrpc_request_addref(req);
 705                 /* Release the async ibits lock ASAP to avoid deadlock
 706                  * when statahead thread tries to enqueue lock on parent
 707                  * for readpage and other tries to enqueue lock on child
 708                  * with parent's lock held, for example: unlink. */
 709                 entry->se_handle = handle;
 710                 if (!sa_has_callback(sai))
 711                         waitq = &sai->sai_thread.t_ctl_waitq;
 712
 713                 list_add_tail(&entry->se_list, &sai->sai_interim_entries);
 714         }
 715         sai->sai_replied++;
 716
 717         smp_mb();
 718         if (waitq != NULL)
 719                 wake_up(waitq);
 720         spin_unlock(&lli->lli_sa_lock);
 721
 722         RETURN(rc);
 723 }
 724
 725 /* finish async stat RPC arguments */
 726 static void sa_fini_data(struct md_enqueue_info *minfo)
 727 {
 728         iput(minfo->mi_dir);
 729         OBD_FREE_PTR(minfo);
 730 }
 731
 732 /*
 733  * prepare arguments for async stat RPC.
 734  */
 735 static struct md_enqueue_info *
 736 sa_prep_data(struct inode *dir, struct inode *child, struct sa_entry *entry)
 737 {
 738         struct md_enqueue_info   *minfo;
 739         struct ldlm_enqueue_info *einfo;
 740         struct md_op_data        *op_data;
 741
 742         OBD_ALLOC_PTR(minfo);
 743         if (minfo == NULL)
 744                 return ERR_PTR(-ENOMEM);
 745
 746         op_data = ll_prep_md_op_data(&minfo->mi_data, dir, child,
 747                                      entry->se_qstr.name, entry->se_qstr.len, 0,
 748                                      LUSTRE_OPC_ANY, NULL);
 749         if (IS_ERR(op_data)) {
 750                 OBD_FREE_PTR(minfo);
 751                 return (struct md_enqueue_info *)op_data;
 752         }
 753
 754         if (child == NULL)
 755                 op_data->op_fid2 = entry->se_fid;
 756
 757         minfo->mi_it.it_op = IT_GETATTR;
 758         minfo->mi_dir = igrab(dir);
 759         minfo->mi_cb = ll_statahead_interpret;
 760         minfo->mi_cbdata = entry;
 761
 762         einfo = &minfo->mi_einfo;
 763         einfo->ei_type   = LDLM_IBITS;
 764         einfo->ei_mode   = it_to_lock_mode(&minfo->mi_it);
 765         einfo->ei_cb_bl  = ll_md_blocking_ast;
 766         einfo->ei_cb_cp  = ldlm_completion_ast;
 767         einfo->ei_cb_gl  = NULL;
 768         einfo->ei_cbdata = NULL;
 769
 770         return minfo;
 771 }
 772
 773 /* async stat for file not found in dcache */
 774 static int sa_lookup(struct inode *dir, struct sa_entry *entry)
 775 {
 776         struct md_enqueue_info   *minfo;
 777         int                       rc;
 778         ENTRY;
 779
 780         minfo = sa_prep_data(dir, NULL, entry);
 781         if (IS_ERR(minfo))
 782                 RETURN(PTR_ERR(minfo));
 783
 784         rc = md_intent_getattr_async(ll_i2mdexp(dir), minfo);
 785         if (rc < 0)
 786                 sa_fini_data(minfo);
 787
 788         RETURN(rc);
 789 }
 790
 791 /**
 792  * async stat for file found in dcache, similar to .revalidate
 793  *
 794  * \retval      1 dentry valid, no RPC sent
 795  * \retval      0 dentry invalid, will send async stat RPC
 796  * \retval      negative number upon error
 797  */
 798 static int sa_revalidate(struct inode *dir, struct sa_entry *entry,
 799                          struct dentry *dentry)
 800 {
 801         struct inode *inode = dentry->d_inode;
 802         struct lookup_intent it = { .it_op = IT_GETATTR,
 803                                     .it_lock_handle = 0 };
 804         struct md_enqueue_info *minfo;
 805         int rc;
 806         ENTRY;
 807
 808         if (unlikely(inode == NULL))
 809                 RETURN(1);
 810
 811         if (d_mountpoint(dentry))
 812                 RETURN(1);
 813
 814         entry->se_inode = igrab(inode);
 815         rc = md_revalidate_lock(ll_i2mdexp(dir), &it, ll_inode2fid(inode),
 816                                 NULL);
 817         if (rc == 1) {
 818                 entry->se_handle = it.it_lock_handle;
 819                 ll_intent_release(&it);
 820                 RETURN(1);
 821         }
 822
 823         minfo = sa_prep_data(dir, inode, entry);
 824         if (IS_ERR(minfo)) {
 825                 entry->se_inode = NULL;
 826                 iput(inode);
 827                 RETURN(PTR_ERR(minfo));
 828         }
 829
 830         rc = md_intent_getattr_async(ll_i2mdexp(dir), minfo);
 831         if (rc < 0) {
 832                 entry->se_inode = NULL;
 833                 iput(inode);
 834                 sa_fini_data(minfo);
 835         }
 836
 837         RETURN(rc);
 838 }
 839
 840 /* async stat for file with @name */
 841 static void sa_statahead(struct dentry *parent, const char *name, int len,
 842                          const struct lu_fid *fid)
 843 {
 844         struct inode *dir = parent->d_inode;
 845         struct ll_inode_info *lli = ll_i2info(dir);
 846         struct ll_statahead_info *sai = lli->lli_sai;
 847         struct dentry *dentry = NULL;
 848         struct sa_entry *entry;
 849         int rc;
 850         ENTRY;
 851
 852         entry = sa_alloc(parent, sai, sai->sai_index, name, len, fid);
 853         if (IS_ERR(entry))
 854                 RETURN_EXIT;
 855
 856         dentry = d_lookup(parent, &entry->se_qstr);
 857         if (!dentry) {
 858                 rc = sa_lookup(dir, entry);
 859         } else {
 860                 rc = sa_revalidate(dir, entry, dentry);
 861                 if (rc == 1 && agl_should_run(sai, dentry->d_inode))
 862                         ll_agl_add(sai, dentry->d_inode, entry->se_index);
 863         }
 864
 865         if (dentry != NULL)
 866                 dput(dentry);
 867
 868         if (rc != 0)
 869                 sa_make_ready(sai, entry, rc);
 870         else
 871                 sai->sai_sent++;
 872
 873         sai->sai_index++;
 874
 875         EXIT;
 876 }
 877
 878 /* async glimpse (agl) thread main function */
 879 static int ll_agl_thread(void *arg)
 880 {
 881         struct dentry *parent = (struct dentry *)arg;
 882         struct inode *dir = parent->d_inode;
 883         struct ll_inode_info *plli = ll_i2info(dir);
 884         struct ll_inode_info *clli;
 885         struct ll_sb_info *sbi = ll_i2sbi(dir);
 886         struct ll_statahead_info *sai;
 887         struct ptlrpc_thread *thread;
 888         struct l_wait_info lwi = { 0 };
 889         ENTRY;
 890
 891
 892         sai = ll_sai_get(dir);
 893         thread = &sai->sai_agl_thread;
 894         thread->t_pid = current_pid();
 895         CDEBUG(D_READA, "agl thread started: sai %p, parent %.*s\n",
 896                sai, parent->d_name.len, parent->d_name.name);
 897
 898         atomic_inc(&sbi->ll_agl_total);
 899         spin_lock(&plli->lli_agl_lock);
 900         sai->sai_agl_valid = 1;
 901         if (thread_is_init(thread))
 902                 /* If someone else has changed the thread state
 903                  * (e.g. already changed to SVC_STOPPING), we can't just
 904                  * blindly overwrite that setting. */
 905                 thread_set_flags(thread, SVC_RUNNING);
 906         spin_unlock(&plli->lli_agl_lock);
 907         wake_up(&thread->t_ctl_waitq);
 908
 909         while (1) {
 910                 l_wait_event(thread->t_ctl_waitq,
 911                              !agl_list_empty(sai) ||
 912                              !thread_is_running(thread),
 913                              &lwi);
 914
 915                 if (!thread_is_running(thread))
 916                         break;
 917
 918                 spin_lock(&plli->lli_agl_lock);
 919                 /* The statahead thread maybe help to process AGL entries,
 920                  * so check whether list empty again. */
 921                 if (!agl_list_empty(sai)) {
 922                         clli = agl_first_entry(sai);
 923                         list_del_init(&clli->lli_agl_list);
 924                         spin_unlock(&plli->lli_agl_lock);
 925                         ll_agl_trigger(&clli->lli_vfs_inode, sai);
 926                 } else {
 927                         spin_unlock(&plli->lli_agl_lock);
 928                 }
 929         }
 930
 931         spin_lock(&plli->lli_agl_lock);
 932         sai->sai_agl_valid = 0;
 933         while (!agl_list_empty(sai)) {
 934                 clli = agl_first_entry(sai);
 935                 list_del_init(&clli->lli_agl_list);
 936                 spin_unlock(&plli->lli_agl_lock);
 937                 clli->lli_agl_index = 0;
 938                 iput(&clli->lli_vfs_inode);
 939                 spin_lock(&plli->lli_agl_lock);
 940         }
 941         thread_set_flags(thread, SVC_STOPPED);
 942         spin_unlock(&plli->lli_agl_lock);
 943         wake_up(&thread->t_ctl_waitq);
 944         ll_sai_put(sai);
 945         CDEBUG(D_READA, "agl thread stopped: sai %p, parent %.*s\n",
 946                sai, parent->d_name.len, parent->d_name.name);
 947         RETURN(0);
 948 }
 949
 950 /* start agl thread */
 951 static void ll_start_agl(struct dentry *parent, struct ll_statahead_info *sai)
 952 {
 953         struct ptlrpc_thread *thread = &sai->sai_agl_thread;
 954         struct l_wait_info    lwi    = { 0 };
 955         struct ll_inode_info  *plli;
 956         struct task_struct            *task;
 957         ENTRY;
 958
 959         CDEBUG(D_READA, "start agl thread: sai %p, parent %.*s\n",
 960                sai, parent->d_name.len, parent->d_name.name);
 961
 962         plli = ll_i2info(parent->d_inode);
 963         task = kthread_run(ll_agl_thread, parent,
 964                                "ll_agl_%u", plli->lli_opendir_pid);
 965         if (IS_ERR(task)) {
 966                 CERROR("can't start ll_agl thread, rc: %ld\n", PTR_ERR(task));
 967                 thread_set_flags(thread, SVC_STOPPED);
 968                 RETURN_EXIT;
 969         }
 970
 971         l_wait_event(thread->t_ctl_waitq,
 972                      thread_is_running(thread) || thread_is_stopped(thread),
 973                      &lwi);
 974         EXIT;
 975 }
 976
 977 /* statahead thread main function */
 978 static int ll_statahead_thread(void *arg)
 979 {
 980         struct dentry *parent = (struct dentry *)arg;
 981         struct inode *dir = parent->d_inode;
 982         struct ll_inode_info *lli = ll_i2info(dir);
 983         struct ll_sb_info *sbi = ll_i2sbi(dir);
 984         struct ll_statahead_info *sai;
 985         struct ptlrpc_thread *sa_thread;
 986         struct ptlrpc_thread *agl_thread;
 987         int first = 0;
 988         struct md_op_data *op_data;
 989         struct ll_dir_chain chain;
 990         struct l_wait_info lwi = { 0 };
 991         struct page *page = NULL;
 992         __u64 pos = 0;
 993         int rc = 0;
 994         ENTRY;
 995
 996         sai = ll_sai_get(dir);
 997         sa_thread = &sai->sai_thread;
 998         agl_thread = &sai->sai_agl_thread;
 999         sa_thread->t_pid = current_pid();
1000         CDEBUG(D_READA, "statahead thread starting: sai %p, parent %.*s\n",
1001                sai, parent->d_name.len, parent->d_name.name);
1002
1003         op_data = ll_prep_md_op_data(NULL, dir, dir, NULL, 0, 0,
1004                                      LUSTRE_OPC_ANY, dir);
1005         if (IS_ERR(op_data))
1006                 GOTO(out, rc = PTR_ERR(op_data));
1007
1008         if (sbi->ll_flags & LL_SBI_AGL_ENABLED)
1009                 ll_start_agl(parent, sai);
1010
1011         atomic_inc(&sbi->ll_sa_total);
1012         spin_lock(&lli->lli_sa_lock);
1013         if (thread_is_init(sa_thread))
1014                 /* If someone else has changed the thread state
1015                  * (e.g. already changed to SVC_STOPPING), we can't just
1016                  * blindly overwrite that setting. */
1017                 thread_set_flags(sa_thread, SVC_RUNNING);
1018         spin_unlock(&lli->lli_sa_lock);
1019         wake_up(&sa_thread->t_ctl_waitq);
1020
1021         ll_dir_chain_init(&chain);
1022         while (pos != MDS_DIR_END_OFF && thread_is_running(sa_thread)) {
1023                 struct lu_dirpage *dp;
1024                 struct lu_dirent  *ent;
1025
1026                 sai->sai_in_readpage = 1;
1027                 page = ll_get_dir_page(dir, op_data, pos, &chain);
1028                 sai->sai_in_readpage = 0;
1029                 if (IS_ERR(page)) {
1030                         rc = PTR_ERR(page);
1031                         CDEBUG(D_READA, "error reading dir "DFID" at %llu"
1032                                "/%llu opendir_pid = %u: rc = %d\n",
1033                                PFID(ll_inode2fid(dir)), pos, sai->sai_index,
1034                                lli->lli_opendir_pid, rc);
1035                         break;
1036                 }
1037
1038                 dp = page_address(page);
1039                 for (ent = lu_dirent_start(dp);
1040                      ent != NULL && thread_is_running(sa_thread) &&
1041                      !sa_low_hit(sai);
1042                      ent = lu_dirent_next(ent)) {
1043                         __u64 hash;
1044                         int namelen;
1045                         char *name;
1046                         struct lu_fid fid;
1047
1048                         hash = le64_to_cpu(ent->lde_hash);
1049                         if (unlikely(hash < pos))
1050                                 /*
1051                                  * Skip until we find target hash value.
1052                                  */
1053                                 continue;
1054
1055                         namelen = le16_to_cpu(ent->lde_namelen);
1056                         if (unlikely(namelen == 0))
1057                                 /*
1058                                  * Skip dummy record.
1059                                  */
1060                                 continue;
1061
1062                         name = ent->lde_name;
1063                         if (name[0] == '.') {
1064                                 if (namelen == 1) {
1065                                         /*
1066                                          * skip "."
1067                                          */
1068                                         continue;
1069                                 } else if (name[1] == '.' && namelen == 2) {
1070                                         /*
1071                                          * skip ".."
1072                                          */
1073                                         continue;
1074                                 } else if (!sai->sai_ls_all) {
1075                                         /*
1076                                          * skip hidden files.
1077                                          */
1078                                         sai->sai_skip_hidden++;
1079                                         continue;
1080                                 }
1081                         }
1082
1083                         /*
1084                          * don't stat-ahead first entry.
1085                          */
1086                         if (unlikely(++first == 1))
1087                                 continue;
1088
1089                         fid_le_to_cpu(&fid, &ent->lde_fid);
1090
1091                         /* wait for spare statahead window */
1092                         do {
1093                                 l_wait_event(sa_thread->t_ctl_waitq,
1094                                              !sa_sent_full(sai) ||
1095                                              sa_has_callback(sai) ||
1096                                              !agl_list_empty(sai) ||
1097                                              !thread_is_running(sa_thread),
1098                                              &lwi);
1099
1100                                 sa_handle_callback(sai);
1101
1102                                 spin_lock(&lli->lli_agl_lock);
1103                                 while (sa_sent_full(sai) &&
1104                                        !agl_list_empty(sai)) {
1105                                         struct ll_inode_info *clli;
1106
1107                                         clli = agl_first_entry(sai);
1108                                         list_del_init(&clli->lli_agl_list);
1109                                         spin_unlock(&lli->lli_agl_lock);
1110
1111                                         ll_agl_trigger(&clli->lli_vfs_inode,
1112                                                         sai);
1113
1114                                         spin_lock(&lli->lli_agl_lock);
1115                                 }
1116                                 spin_unlock(&lli->lli_agl_lock);
1117                         } while (sa_sent_full(sai) &&
1118                                  thread_is_running(sa_thread));
1119
1120                         sa_statahead(parent, name, namelen, &fid);
1121                 }
1122
1123                 pos = le64_to_cpu(dp->ldp_hash_end);
1124                 ll_release_page(dir, page,
1125                                 le32_to_cpu(dp->ldp_flags) & LDF_COLLIDE);
1126
1127                 if (sa_low_hit(sai)) {
1128                         rc = -EFAULT;
1129                         atomic_inc(&sbi->ll_sa_wrong);
1130                         CDEBUG(D_READA, "Statahead for dir "DFID" hit "
1131                                "ratio too low: hit/miss %llu/%llu"
1132                                ", sent/replied %llu/%llu, stopping "
1133                                "statahead thread: pid %d\n",
1134                                PFID(&lli->lli_fid), sai->sai_hit,
1135                                sai->sai_miss, sai->sai_sent,
1136                                sai->sai_replied, current_pid());
1137                         break;
1138                 }
1139         }
1140         ll_dir_chain_fini(&chain);
1141         ll_finish_md_op_data(op_data);
1142
1143         if (rc < 0) {
1144                 spin_lock(&lli->lli_sa_lock);
1145                 thread_set_flags(sa_thread, SVC_STOPPING);
1146                 lli->lli_sa_enabled = 0;
1147                 spin_unlock(&lli->lli_sa_lock);
1148         }
1149
1150         /* statahead is finished, but statahead entries need to be cached, wait
1151          * for file release to stop me. */
1152         while (thread_is_running(sa_thread)) {
1153                 l_wait_event(sa_thread->t_ctl_waitq,
1154                              sa_has_callback(sai) ||
1155                              !thread_is_running(sa_thread),
1156                              &lwi);
1157
1158                 sa_handle_callback(sai);
1159         }
1160
1161         EXIT;
1162 out:
1163         if (sai->sai_agl_valid) {
1164                 spin_lock(&lli->lli_agl_lock);
1165                 thread_set_flags(agl_thread, SVC_STOPPING);
1166                 spin_unlock(&lli->lli_agl_lock);
1167                 wake_up(&agl_thread->t_ctl_waitq);
1168
1169                 CDEBUG(D_READA, "stop agl thread: sai %p pid %u\n",
1170                        sai, (unsigned int)agl_thread->t_pid);
1171                 l_wait_event(agl_thread->t_ctl_waitq,
1172                              thread_is_stopped(agl_thread),
1173                              &lwi);
1174         } else {
1175                 /* Set agl_thread flags anyway. */
1176                 thread_set_flags(agl_thread, SVC_STOPPED);
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         while (sai->sai_sent != sai->sai_replied) {
1182                 /* in case we're not woken up, timeout wait */
1183                 lwi = LWI_TIMEOUT(msecs_to_jiffies(MSEC_PER_SEC >> 3),
1184                                   NULL, NULL);
1185                 l_wait_event(sa_thread->t_ctl_waitq,
1186                         sai->sai_sent == sai->sai_replied, &lwi);
1187         }
1188
1189         /* release resources held by statahead RPCs */
1190         sa_handle_callback(sai);
1191
1192         spin_lock(&lli->lli_sa_lock);
1193         thread_set_flags(sa_thread, SVC_STOPPED);
1194         spin_unlock(&lli->lli_sa_lock);
1195
1196         CDEBUG(D_READA, "statahead thread stopped: sai %p, parent %.*s\n",
1197                sai, parent->d_name.len, parent->d_name.name);
1198
1199         wake_up(&sai->sai_waitq);
1200         wake_up(&sa_thread->t_ctl_waitq);
1201         ll_sai_put(sai);
1202
1203         return rc;
1204 }
1205
1206 /* authorize opened dir handle @key to statahead */
1207 void ll_authorize_statahead(struct inode *dir, void *key)
1208 {
1209         struct ll_inode_info *lli = ll_i2info(dir);
1210
1211         spin_lock(&lli->lli_sa_lock);
1212         if (lli->lli_opendir_key == NULL && lli->lli_sai == NULL) {
1213                 /*
1214                  * if lli_sai is not NULL, it means previous statahead is not
1215                  * finished yet, we'd better not start a new statahead for now.
1216                  */
1217                 LASSERT(lli->lli_opendir_pid == 0);
1218                 lli->lli_opendir_key = key;
1219                 lli->lli_opendir_pid = current_pid();
1220                 lli->lli_sa_enabled = 1;
1221         }
1222         spin_unlock(&lli->lli_sa_lock);
1223 }
1224
1225 /*
1226  * deauthorize opened dir handle @key to statahead, and notify statahead thread
1227  * to quit if it's running.
1228  */
1229 void ll_deauthorize_statahead(struct inode *dir, void *key)
1230 {
1231         struct ll_inode_info *lli = ll_i2info(dir);
1232         struct ll_statahead_info *sai;
1233
1234         LASSERT(lli->lli_opendir_key == key);
1235         LASSERT(lli->lli_opendir_pid != 0);
1236
1237         CDEBUG(D_READA, "deauthorize statahead for "DFID"\n",
1238                 PFID(&lli->lli_fid));
1239
1240         spin_lock(&lli->lli_sa_lock);
1241         lli->lli_opendir_key = NULL;
1242         lli->lli_opendir_pid = 0;
1243         lli->lli_sa_enabled = 0;
1244         sai = lli->lli_sai;
1245         if (sai != NULL && thread_is_running(&sai->sai_thread)) {
1246                 /*
1247                  * statahead thread may not quit yet because it needs to cache
1248                  * entries, now it's time to tell it to quit.
1249                  *
1250                  * In case sai is released, wake_up() is called inside spinlock,
1251                  * so we have to call smp_mb() explicitely to serialize ops.
1252                  */
1253                 thread_set_flags(&sai->sai_thread, SVC_STOPPING);
1254                 smp_mb();
1255                 wake_up(&sai->sai_thread.t_ctl_waitq);
1256         }
1257         spin_unlock(&lli->lli_sa_lock);
1258 }
1259
1260 enum {
1261         /**
1262          * not first dirent, or is "."
1263          */
1264         LS_NOT_FIRST_DE = 0,
1265         /**
1266          * the first non-hidden dirent
1267          */
1268         LS_FIRST_DE,
1269         /**
1270          * the first hidden dirent, that is "."
1271          */
1272         LS_FIRST_DOT_DE
1273 };
1274
1275 /* file is first dirent under @dir */
1276 static int is_first_dirent(struct inode *dir, struct dentry *dentry)
1277 {
1278         struct ll_dir_chain   chain;
1279         struct qstr          *target = &dentry->d_name;
1280         struct md_op_data    *op_data;
1281         int                   dot_de;
1282         struct page          *page = NULL;
1283         int                   rc = LS_NOT_FIRST_DE;
1284         __u64                 pos = 0;
1285         ENTRY;
1286
1287         op_data = ll_prep_md_op_data(NULL, dir, dir, NULL, 0, 0,
1288                                      LUSTRE_OPC_ANY, dir);
1289         if (IS_ERR(op_data))
1290                 RETURN(PTR_ERR(op_data));
1291         /**
1292          *FIXME choose the start offset of the readdir
1293          */
1294
1295         ll_dir_chain_init(&chain);
1296         page = ll_get_dir_page(dir, op_data, 0, &chain);
1297
1298         while (1) {
1299                 struct lu_dirpage *dp;
1300                 struct lu_dirent  *ent;
1301
1302                 if (IS_ERR(page)) {
1303                         struct ll_inode_info *lli = ll_i2info(dir);
1304
1305                         rc = PTR_ERR(page);
1306                         CERROR("%s: reading dir "DFID" at %llu"
1307                                "opendir_pid = %u : rc = %d\n",
1308                                ll_get_fsname(dir->i_sb, NULL, 0),
1309                                PFID(ll_inode2fid(dir)), pos,
1310                                lli->lli_opendir_pid, rc);
1311                         break;
1312                 }
1313
1314                 dp = page_address(page);
1315                 for (ent = lu_dirent_start(dp); ent != NULL;
1316                      ent = lu_dirent_next(ent)) {
1317                         __u64 hash;
1318                         int namelen;
1319                         char *name;
1320
1321                         hash = le64_to_cpu(ent->lde_hash);
1322                         /* The ll_get_dir_page() can return any page containing
1323                          * the given hash which may be not the start hash. */
1324                         if (unlikely(hash < pos))
1325                                 continue;
1326
1327                         namelen = le16_to_cpu(ent->lde_namelen);
1328                         if (unlikely(namelen == 0))
1329                                 /*
1330                                  * skip dummy record.
1331                                  */
1332                                 continue;
1333
1334                         name = ent->lde_name;
1335                         if (name[0] == '.') {
1336                                 if (namelen == 1)
1337                                         /*
1338                                          * skip "."
1339                                          */
1340                                         continue;
1341                                 else if (name[1] == '.' && namelen == 2)
1342                                         /*
1343                                          * skip ".."
1344                                          */
1345                                         continue;
1346                                 else
1347                                         dot_de = 1;
1348                         } else {
1349                                 dot_de = 0;
1350                         }
1351
1352                         if (dot_de && target->name[0] != '.') {
1353                                 CDEBUG(D_READA, "%.*s skip hidden file %.*s\n",
1354                                        target->len, target->name,
1355                                        namelen, name);
1356                                 continue;
1357                         }
1358
1359                         if (target->len != namelen ||
1360                             memcmp(target->name, name, namelen) != 0)
1361                                 rc = LS_NOT_FIRST_DE;
1362                         else if (!dot_de)
1363                                 rc = LS_FIRST_DE;
1364                         else
1365                                 rc = LS_FIRST_DOT_DE;
1366
1367                         ll_release_page(dir, page, false);
1368                         GOTO(out, rc);
1369                 }
1370                 pos = le64_to_cpu(dp->ldp_hash_end);
1371                 if (pos == MDS_DIR_END_OFF) {
1372                         /*
1373                          * End of directory reached.
1374                          */
1375                         ll_release_page(dir, page, false);
1376                         GOTO(out, rc);
1377                 } else {
1378                         /*
1379                          * chain is exhausted
1380                          * Normal case: continue to the next page.
1381                          */
1382                         ll_release_page(dir, page, le32_to_cpu(dp->ldp_flags) &
1383                                               LDF_COLLIDE);
1384                         page = ll_get_dir_page(dir, op_data, pos, &chain);
1385                 }
1386         }
1387         EXIT;
1388 out:
1389         ll_dir_chain_fini(&chain);
1390         ll_finish_md_op_data(op_data);
1391         return rc;
1392 }
1393
1394 /**
1395  * revalidate @dentryp from statahead cache
1396  *
1397  * \param[in] dir       parent directory
1398  * \param[in] sai       sai structure
1399  * \param[out] dentryp  pointer to dentry which will be revalidated
1400  * \param[in] unplug    unplug statahead window only (normally for negative
1401  *                      dentry)
1402  * \retval              1 on success, dentry is saved in @dentryp
1403  * \retval              0 if revalidation failed (no proper lock on client)
1404  * \retval              negative number upon error
1405  */
1406 static int revalidate_statahead_dentry(struct inode *dir,
1407                                         struct ll_statahead_info *sai,
1408                                         struct dentry **dentryp,
1409                                         bool unplug)
1410 {
1411         struct sa_entry *entry = NULL;
1412         struct l_wait_info lwi = { 0 };
1413         struct ll_dentry_data *ldd;
1414         struct ll_inode_info *lli = ll_i2info(dir);
1415         int rc = 0;
1416         ENTRY;
1417
1418         if ((*dentryp)->d_name.name[0] == '.') {
1419                 if (sai->sai_ls_all ||
1420                     sai->sai_miss_hidden >= sai->sai_skip_hidden) {
1421                         /*
1422                          * Hidden dentry is the first one, or statahead
1423                          * thread does not skip so many hidden dentries
1424                          * before "sai_ls_all" enabled as below.
1425                          */
1426                 } else {
1427                         if (!sai->sai_ls_all)
1428                                 /*
1429                                  * It maybe because hidden dentry is not
1430                                  * the first one, "sai_ls_all" was not
1431                                  * set, then "ls -al" missed. Enable
1432                                  * "sai_ls_all" for such case.
1433                                  */
1434                                 sai->sai_ls_all = 1;
1435
1436                         /*
1437                          * Such "getattr" has been skipped before
1438                          * "sai_ls_all" enabled as above.
1439                          */
1440                         sai->sai_miss_hidden++;
1441                         RETURN(-EAGAIN);
1442                 }
1443         }
1444
1445         if (unplug)
1446                 GOTO(out, rc = 1);
1447
1448         entry = sa_get(sai, &(*dentryp)->d_name);
1449         if (entry == NULL)
1450                 GOTO(out, rc = -EAGAIN);
1451
1452         /* if statahead is busy in readdir, help it do post-work */
1453         if (!sa_ready(entry) && sai->sai_in_readpage)
1454                 sa_handle_callback(sai);
1455
1456         if (!sa_ready(entry)) {
1457                 spin_lock(&lli->lli_sa_lock);
1458                 sai->sai_index_wait = entry->se_index;
1459                 spin_unlock(&lli->lli_sa_lock);
1460                 lwi = LWI_TIMEOUT_INTR(cfs_time_seconds(30), NULL,
1461                                        LWI_ON_SIGNAL_NOOP, NULL);
1462                 rc = l_wait_event(sai->sai_waitq, sa_ready(entry), &lwi);
1463                 if (rc < 0) {
1464                         /*
1465                          * entry may not be ready, so it may be used by inflight
1466                          * statahead RPC, don't free it.
1467                          */
1468                         entry = NULL;
1469                         GOTO(out, rc = -EAGAIN);
1470                 }
1471         }
1472
1473         if (entry->se_state == SA_ENTRY_SUCC && entry->se_inode != NULL) {
1474                 struct inode *inode = entry->se_inode;
1475                 struct lookup_intent it = { .it_op = IT_GETATTR,
1476                                             .it_lock_handle =
1477                                                 entry->se_handle };
1478                 __u64 bits;
1479
1480                 rc = md_revalidate_lock(ll_i2mdexp(dir), &it,
1481                                         ll_inode2fid(inode), &bits);
1482                 if (rc == 1) {
1483                         if ((*dentryp)->d_inode == NULL) {
1484                                 struct dentry *alias;
1485
1486                                 alias = ll_splice_alias(inode, *dentryp);
1487                                 if (IS_ERR(alias)) {
1488                                         ll_intent_release(&it);
1489                                         GOTO(out, rc = PTR_ERR(alias));
1490                                 }
1491                                 *dentryp = alias;
1492                                 /* statahead prepared this inode, transfer inode
1493                                  * refcount from sa_entry to dentry */
1494                                 entry->se_inode = NULL;
1495                         } else if ((*dentryp)->d_inode != inode) {
1496                                 /* revalidate, but inode is recreated */
1497                                 CDEBUG(D_READA,
1498                                         "%s: stale dentry %.*s inode "
1499                                         DFID", statahead inode "DFID
1500                                         "\n",
1501                                         ll_get_fsname((*dentryp)->d_inode->i_sb,
1502                                                       NULL, 0),
1503                                         (*dentryp)->d_name.len,
1504                                         (*dentryp)->d_name.name,
1505                                         PFID(ll_inode2fid((*dentryp)->d_inode)),
1506                                         PFID(ll_inode2fid(inode)));
1507                                 ll_intent_release(&it);
1508                                 GOTO(out, rc = -ESTALE);
1509                         }
1510
1511                         if ((bits & MDS_INODELOCK_LOOKUP) &&
1512                             d_lustre_invalid(*dentryp))
1513                                 d_lustre_revalidate(*dentryp);
1514                         ll_intent_release(&it);
1515                 }
1516         }
1517 out:
1518         /*
1519          * statahead cached sa_entry can be used only once, and will be killed
1520          * right after use, so if lookup/revalidate accessed statahead cache,
1521          * set dentry ldd_sa_generation to parent lli_sa_generation, later if we
1522          * stat this file again, we know we've done statahead before, see
1523          * dentry_may_statahead().
1524          */
1525         ldd = ll_d2d(*dentryp);
1526         /* ldd can be NULL if llite lookup failed. */
1527         if (ldd != NULL)
1528                 ldd->lld_sa_generation = lli->lli_sa_generation;
1529         sa_put(sai, entry);
1530
1531         RETURN(rc);
1532 }
1533
1534 /**
1535  * start statahead thread
1536  *
1537  * \param[in] dir       parent directory
1538  * \param[in] dentry    dentry that triggers statahead, normally the first
1539  *                      dirent under @dir
1540  * \retval              -EAGAIN on success, because when this function is
1541  *                      called, it's already in lookup call, so client should
1542  *                      do it itself instead of waiting for statahead thread
1543  *                      to do it asynchronously.
1544  * \retval              negative number upon error
1545  */
1546 static int start_statahead_thread(struct inode *dir, struct dentry *dentry)
1547 {
1548         struct ll_inode_info *lli = ll_i2info(dir);
1549         struct ll_statahead_info *sai = NULL;
1550         struct dentry *parent = dentry->d_parent;
1551         struct ptlrpc_thread *thread;
1552         struct l_wait_info lwi = { 0 };
1553         struct task_struct *task;
1554         int rc;
1555         ENTRY;
1556
1557         /* I am the "lli_opendir_pid" owner, only me can set "lli_sai". */
1558         rc = is_first_dirent(dir, dentry);
1559         if (rc == LS_NOT_FIRST_DE)
1560                 /* It is not "ls -{a}l" operation, no need statahead for it. */
1561                 GOTO(out, rc = -EFAULT);
1562
1563         sai = ll_sai_alloc(parent);
1564         if (sai == NULL)
1565                 GOTO(out, rc = -ENOMEM);
1566
1567         sai->sai_ls_all = (rc == LS_FIRST_DOT_DE);
1568
1569         /* if current lli_opendir_key was deauthorized, or dir re-opened by
1570          * another process, don't start statahead, otherwise the newly spawned
1571          * statahead thread won't be notified to quit. */
1572         spin_lock(&lli->lli_sa_lock);
1573         if (unlikely(lli->lli_sai != NULL ||
1574                      lli->lli_opendir_key == NULL ||
1575                      lli->lli_opendir_pid != current->pid)) {
1576                 spin_unlock(&lli->lli_sa_lock);
1577                 GOTO(out, rc = -EPERM);
1578         }
1579         lli->lli_sai = sai;
1580         spin_unlock(&lli->lli_sa_lock);
1581
1582         atomic_inc(&ll_i2sbi(parent->d_inode)->ll_sa_running);
1583
1584         CDEBUG(D_READA, "start statahead thread: [pid %d] [parent %.*s]\n",
1585                current_pid(), parent->d_name.len, parent->d_name.name);
1586
1587         task = kthread_run(ll_statahead_thread, parent, "ll_sa_%u",
1588                            lli->lli_opendir_pid);
1589         thread = &sai->sai_thread;
1590         if (IS_ERR(task)) {
1591                 spin_lock(&lli->lli_sa_lock);
1592                 lli->lli_sai = NULL;
1593                 spin_unlock(&lli->lli_sa_lock);
1594                 rc = PTR_ERR(task);
1595                 CERROR("can't start ll_sa thread, rc: %d\n", rc);
1596                 GOTO(out, rc);
1597         }
1598
1599         l_wait_event(thread->t_ctl_waitq,
1600                      thread_is_running(thread) || thread_is_stopped(thread),
1601                      &lwi);
1602         ll_sai_put(sai);
1603
1604         /*
1605          * We don't stat-ahead for the first dirent since we are already in
1606          * lookup.
1607          */
1608         RETURN(-EAGAIN);
1609
1610 out:
1611         /* once we start statahead thread failed, disable statahead so that
1612          * subsequent stat won't waste time to try it. */
1613         spin_lock(&lli->lli_sa_lock);
1614         if (lli->lli_opendir_pid == current->pid)
1615                 lli->lli_sa_enabled = 0;
1616         spin_unlock(&lli->lli_sa_lock);
1617
1618         if (sai != NULL)
1619                 ll_sai_free(sai);
1620
1621         RETURN(rc);
1622 }
1623
1624 /**
1625  * statahead entry function, this is called when client getattr on a file, it
1626  * will start statahead thread if this is the first dir entry, else revalidate
1627  * dentry from statahead cache.
1628  *
1629  * \param[in]  dir      parent directory
1630  * \param[out] dentryp  dentry to getattr
1631  * \param[in]  unplug   unplug statahead window only (normally for negative
1632  *                      dentry)
1633  * \retval              1 on success
1634  * \retval              0 revalidation from statahead cache failed, caller needs
1635  *                      to getattr from server directly
1636  * \retval              negative number on error, caller often ignores this and
1637  *                      then getattr from server
1638  */
1639 int ll_statahead(struct inode *dir, struct dentry **dentryp, bool unplug)
1640 {
1641         struct ll_statahead_info *sai;
1642
1643         sai = ll_sai_get(dir);
1644         if (sai != NULL) {
1645                 int rc;
1646
1647                 rc = revalidate_statahead_dentry(dir, sai, dentryp, unplug);
1648                 CDEBUG(D_READA, "revalidate statahead %.*s: %d.\n",
1649                         (*dentryp)->d_name.len, (*dentryp)->d_name.name, rc);
1650                 ll_sai_put(sai);
1651                 return rc;
1652         }
1653         return start_statahead_thread(dir, *dentryp);
1654 }