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 ll_statahead_info *sai, __u64 index, const char *name, int len,
 183          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 = full_name_hash(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         if (waitq != NULL)
 717                 wake_up(waitq);
 718         spin_unlock(&lli->lli_sa_lock);
 719
 720         RETURN(rc);
 721 }
 722
 723 /* finish async stat RPC arguments */
 724 static void sa_fini_data(struct md_enqueue_info *minfo)
 725 {
 726         iput(minfo->mi_dir);
 727         OBD_FREE_PTR(minfo);
 728 }
 729
 730 /*
 731  * prepare arguments for async stat RPC.
 732  */
 733 static struct md_enqueue_info *
 734 sa_prep_data(struct inode *dir, struct inode *child, struct sa_entry *entry)
 735 {
 736         struct md_enqueue_info   *minfo;
 737         struct ldlm_enqueue_info *einfo;
 738         struct md_op_data        *op_data;
 739
 740         OBD_ALLOC_PTR(minfo);
 741         if (minfo == NULL)
 742                 return ERR_PTR(-ENOMEM);
 743
 744         op_data = ll_prep_md_op_data(&minfo->mi_data, dir, child, NULL, 0, 0,
 745                                      LUSTRE_OPC_ANY, NULL);
 746         if (IS_ERR(op_data)) {
 747                 OBD_FREE_PTR(minfo);
 748                 return (struct md_enqueue_info *)op_data;
 749         }
 750
 751         if (child == NULL)
 752                 op_data->op_fid2 = entry->se_fid;
 753
 754         minfo->mi_it.it_op = IT_GETATTR;
 755         minfo->mi_dir = igrab(dir);
 756         minfo->mi_cb = ll_statahead_interpret;
 757         minfo->mi_cbdata = entry;
 758
 759         einfo = &minfo->mi_einfo;
 760         einfo->ei_type   = LDLM_IBITS;
 761         einfo->ei_mode   = it_to_lock_mode(&minfo->mi_it);
 762         einfo->ei_cb_bl  = ll_md_blocking_ast;
 763         einfo->ei_cb_cp  = ldlm_completion_ast;
 764         einfo->ei_cb_gl  = NULL;
 765         einfo->ei_cbdata = NULL;
 766
 767         return minfo;
 768 }
 769
 770 /* async stat for file not found in dcache */
 771 static int sa_lookup(struct inode *dir, struct sa_entry *entry)
 772 {
 773         struct md_enqueue_info   *minfo;
 774         int                       rc;
 775         ENTRY;
 776
 777         minfo = sa_prep_data(dir, NULL, entry);
 778         if (IS_ERR(minfo))
 779                 RETURN(PTR_ERR(minfo));
 780
 781         rc = md_intent_getattr_async(ll_i2mdexp(dir), minfo);
 782         if (rc < 0)
 783                 sa_fini_data(minfo);
 784
 785         RETURN(rc);
 786 }
 787
 788 /**
 789  * async stat for file found in dcache, similar to .revalidate
 790  *
 791  * \retval      1 dentry valid, no RPC sent
 792  * \retval      0 dentry invalid, will send async stat RPC
 793  * \retval      negative number upon error
 794  */
 795 static int sa_revalidate(struct inode *dir, struct sa_entry *entry,
 796                          struct dentry *dentry)
 797 {
 798         struct inode *inode = dentry->d_inode;
 799         struct lookup_intent it = { .it_op = IT_GETATTR,
 800                                     .it_lock_handle = 0 };
 801         struct md_enqueue_info *minfo;
 802         int rc;
 803         ENTRY;
 804
 805         if (unlikely(inode == NULL))
 806                 RETURN(1);
 807
 808         if (d_mountpoint(dentry))
 809                 RETURN(1);
 810
 811         entry->se_inode = igrab(inode);
 812         rc = md_revalidate_lock(ll_i2mdexp(dir), &it, ll_inode2fid(inode),
 813                                 NULL);
 814         if (rc == 1) {
 815                 entry->se_handle = it.it_lock_handle;
 816                 ll_intent_release(&it);
 817                 RETURN(1);
 818         }
 819
 820         minfo = sa_prep_data(dir, inode, entry);
 821         if (IS_ERR(minfo)) {
 822                 entry->se_inode = NULL;
 823                 iput(inode);
 824                 RETURN(PTR_ERR(minfo));
 825         }
 826
 827         rc = md_intent_getattr_async(ll_i2mdexp(dir), minfo);
 828         if (rc < 0) {
 829                 entry->se_inode = NULL;
 830                 iput(inode);
 831                 sa_fini_data(minfo);
 832         }
 833
 834         RETURN(rc);
 835 }
 836
 837 /* async stat for file with @name */
 838 static void sa_statahead(struct dentry *parent, const char *name, int len,
 839                          const struct lu_fid *fid)
 840 {
 841         struct inode *dir = parent->d_inode;
 842         struct ll_inode_info *lli = ll_i2info(dir);
 843         struct ll_statahead_info *sai = lli->lli_sai;
 844         struct dentry *dentry = NULL;
 845         struct sa_entry *entry;
 846         int rc;
 847         ENTRY;
 848
 849         entry = sa_alloc(sai, sai->sai_index, name, len, fid);
 850         if (IS_ERR(entry))
 851                 RETURN_EXIT;
 852
 853         dentry = d_lookup(parent, &entry->se_qstr);
 854         if (!dentry) {
 855                 rc = sa_lookup(dir, entry);
 856         } else {
 857                 rc = sa_revalidate(dir, entry, dentry);
 858                 if (rc == 1 && agl_should_run(sai, dentry->d_inode))
 859                         ll_agl_add(sai, dentry->d_inode, entry->se_index);
 860         }
 861
 862         if (dentry != NULL)
 863                 dput(dentry);
 864
 865         if (rc != 0)
 866                 sa_make_ready(sai, entry, rc);
 867         else
 868                 sai->sai_sent++;
 869
 870         sai->sai_index++;
 871
 872         EXIT;
 873 }
 874
 875 /* async glimpse (agl) thread main function */
 876 static int ll_agl_thread(void *arg)
 877 {
 878         struct dentry *parent = (struct dentry *)arg;
 879         struct inode *dir = parent->d_inode;
 880         struct ll_inode_info *plli = ll_i2info(dir);
 881         struct ll_inode_info *clli;
 882         struct ll_sb_info *sbi = ll_i2sbi(dir);
 883         struct ll_statahead_info *sai;
 884         struct ptlrpc_thread *thread;
 885         struct l_wait_info lwi = { 0 };
 886         ENTRY;
 887
 888
 889         sai = ll_sai_get(dir);
 890         thread = &sai->sai_agl_thread;
 891         thread->t_pid = current_pid();
 892         CDEBUG(D_READA, "agl thread started: sai %p, parent %.*s\n",
 893                sai, parent->d_name.len, parent->d_name.name);
 894
 895         atomic_inc(&sbi->ll_agl_total);
 896         spin_lock(&plli->lli_agl_lock);
 897         sai->sai_agl_valid = 1;
 898         if (thread_is_init(thread))
 899                 /* If someone else has changed the thread state
 900                  * (e.g. already changed to SVC_STOPPING), we can't just
 901                  * blindly overwrite that setting. */
 902                 thread_set_flags(thread, SVC_RUNNING);
 903         spin_unlock(&plli->lli_agl_lock);
 904         wake_up(&thread->t_ctl_waitq);
 905
 906         while (1) {
 907                 l_wait_event(thread->t_ctl_waitq,
 908                              !agl_list_empty(sai) ||
 909                              !thread_is_running(thread),
 910                              &lwi);
 911
 912                 if (!thread_is_running(thread))
 913                         break;
 914
 915                 spin_lock(&plli->lli_agl_lock);
 916                 /* The statahead thread maybe help to process AGL entries,
 917                  * so check whether list empty again. */
 918                 if (!agl_list_empty(sai)) {
 919                         clli = agl_first_entry(sai);
 920                         list_del_init(&clli->lli_agl_list);
 921                         spin_unlock(&plli->lli_agl_lock);
 922                         ll_agl_trigger(&clli->lli_vfs_inode, sai);
 923                 } else {
 924                         spin_unlock(&plli->lli_agl_lock);
 925                 }
 926         }
 927
 928         spin_lock(&plli->lli_agl_lock);
 929         sai->sai_agl_valid = 0;
 930         while (!agl_list_empty(sai)) {
 931                 clli = agl_first_entry(sai);
 932                 list_del_init(&clli->lli_agl_list);
 933                 spin_unlock(&plli->lli_agl_lock);
 934                 clli->lli_agl_index = 0;
 935                 iput(&clli->lli_vfs_inode);
 936                 spin_lock(&plli->lli_agl_lock);
 937         }
 938         thread_set_flags(thread, SVC_STOPPED);
 939         spin_unlock(&plli->lli_agl_lock);
 940         wake_up(&thread->t_ctl_waitq);
 941         ll_sai_put(sai);
 942         CDEBUG(D_READA, "agl thread stopped: sai %p, parent %.*s\n",
 943                sai, parent->d_name.len, parent->d_name.name);
 944         RETURN(0);
 945 }
 946
 947 /* start agl thread */
 948 static void ll_start_agl(struct dentry *parent, struct ll_statahead_info *sai)
 949 {
 950         struct ptlrpc_thread *thread = &sai->sai_agl_thread;
 951         struct l_wait_info    lwi    = { 0 };
 952         struct ll_inode_info  *plli;
 953         struct task_struct            *task;
 954         ENTRY;
 955
 956         CDEBUG(D_READA, "start agl thread: sai %p, parent %.*s\n",
 957                sai, parent->d_name.len, parent->d_name.name);
 958
 959         plli = ll_i2info(parent->d_inode);
 960         task = kthread_run(ll_agl_thread, parent,
 961                                "ll_agl_%u", plli->lli_opendir_pid);
 962         if (IS_ERR(task)) {
 963                 CERROR("can't start ll_agl thread, rc: %ld\n", PTR_ERR(task));
 964                 thread_set_flags(thread, SVC_STOPPED);
 965                 RETURN_EXIT;
 966         }
 967
 968         l_wait_event(thread->t_ctl_waitq,
 969                      thread_is_running(thread) || thread_is_stopped(thread),
 970                      &lwi);
 971         EXIT;
 972 }
 973
 974 /* statahead thread main function */
 975 static int ll_statahead_thread(void *arg)
 976 {
 977         struct dentry *parent = (struct dentry *)arg;
 978         struct inode *dir = parent->d_inode;
 979         struct ll_inode_info *lli = ll_i2info(dir);
 980         struct ll_sb_info *sbi = ll_i2sbi(dir);
 981         struct ll_statahead_info *sai;
 982         struct ptlrpc_thread *sa_thread;
 983         struct ptlrpc_thread *agl_thread;
 984         int first = 0;
 985         struct md_op_data *op_data;
 986         struct ll_dir_chain chain;
 987         struct l_wait_info lwi = { 0 };
 988         struct page *page = NULL;
 989         __u64 pos = 0;
 990         int rc = 0;
 991         ENTRY;
 992
 993         sai = ll_sai_get(dir);
 994         sa_thread = &sai->sai_thread;
 995         agl_thread = &sai->sai_agl_thread;
 996         sa_thread->t_pid = current_pid();
 997         CDEBUG(D_READA, "statahead thread starting: sai %p, parent %.*s\n",
 998                sai, parent->d_name.len, parent->d_name.name);
 999
1000         op_data = ll_prep_md_op_data(NULL, dir, dir, NULL, 0, 0,
1001                                      LUSTRE_OPC_ANY, dir);
1002         if (IS_ERR(op_data))
1003                 GOTO(out, rc = PTR_ERR(op_data));
1004
1005         op_data->op_max_pages = ll_i2sbi(dir)->ll_md_brw_pages;
1006
1007         if (sbi->ll_flags & LL_SBI_AGL_ENABLED)
1008                 ll_start_agl(parent, sai);
1009
1010         atomic_inc(&sbi->ll_sa_total);
1011         spin_lock(&lli->lli_sa_lock);
1012         if (thread_is_init(sa_thread))
1013                 /* If someone else has changed the thread state
1014                  * (e.g. already changed to SVC_STOPPING), we can't just
1015                  * blindly overwrite that setting. */
1016                 thread_set_flags(sa_thread, SVC_RUNNING);
1017         spin_unlock(&lli->lli_sa_lock);
1018         wake_up(&sa_thread->t_ctl_waitq);
1019
1020         ll_dir_chain_init(&chain);
1021         while (pos != MDS_DIR_END_OFF && thread_is_running(sa_thread)) {
1022                 struct lu_dirpage *dp;
1023                 struct lu_dirent  *ent;
1024
1025                 sai->sai_in_readpage = 1;
1026                 page = ll_get_dir_page(dir, op_data, pos, &chain);
1027                 sai->sai_in_readpage = 0;
1028                 if (IS_ERR(page)) {
1029                         rc = PTR_ERR(page);
1030                         CDEBUG(D_READA, "error reading dir "DFID" at %llu"
1031                                "/%llu opendir_pid = %u: rc = %d\n",
1032                                PFID(ll_inode2fid(dir)), pos, sai->sai_index,
1033                                lli->lli_opendir_pid, rc);
1034                         break;
1035                 }
1036
1037                 dp = page_address(page);
1038                 for (ent = lu_dirent_start(dp);
1039                      ent != NULL && thread_is_running(sa_thread) &&
1040                      !sa_low_hit(sai);
1041                      ent = lu_dirent_next(ent)) {
1042                         __u64 hash;
1043                         int namelen;
1044                         char *name;
1045                         struct lu_fid fid;
1046
1047                         hash = le64_to_cpu(ent->lde_hash);
1048                         if (unlikely(hash < pos))
1049                                 /*
1050                                  * Skip until we find target hash value.
1051                                  */
1052                                 continue;
1053
1054                         namelen = le16_to_cpu(ent->lde_namelen);
1055                         if (unlikely(namelen == 0))
1056                                 /*
1057                                  * Skip dummy record.
1058                                  */
1059                                 continue;
1060
1061                         name = ent->lde_name;
1062                         if (name[0] == '.') {
1063                                 if (namelen == 1) {
1064                                         /*
1065                                          * skip "."
1066                                          */
1067                                         continue;
1068                                 } else if (name[1] == '.' && namelen == 2) {
1069                                         /*
1070                                          * skip ".."
1071                                          */
1072                                         continue;
1073                                 } else if (!sai->sai_ls_all) {
1074                                         /*
1075                                          * skip hidden files.
1076                                          */
1077                                         sai->sai_skip_hidden++;
1078                                         continue;
1079                                 }
1080                         }
1081
1082                         /*
1083                          * don't stat-ahead first entry.
1084                          */
1085                         if (unlikely(++first == 1))
1086                                 continue;
1087
1088                         fid_le_to_cpu(&fid, &ent->lde_fid);
1089
1090                         /* wait for spare statahead window */
1091                         do {
1092                                 l_wait_event(sa_thread->t_ctl_waitq,
1093                                              !sa_sent_full(sai) ||
1094                                              sa_has_callback(sai) ||
1095                                              !agl_list_empty(sai) ||
1096                                              !thread_is_running(sa_thread),
1097                                              &lwi);
1098
1099                                 sa_handle_callback(sai);
1100
1101                                 spin_lock(&lli->lli_agl_lock);
1102                                 while (sa_sent_full(sai) &&
1103                                        !agl_list_empty(sai)) {
1104                                         struct ll_inode_info *clli;
1105
1106                                         clli = agl_first_entry(sai);
1107                                         list_del_init(&clli->lli_agl_list);
1108                                         spin_unlock(&lli->lli_agl_lock);
1109
1110                                         ll_agl_trigger(&clli->lli_vfs_inode,
1111                                                         sai);
1112
1113                                         spin_lock(&lli->lli_agl_lock);
1114                                 }
1115                                 spin_unlock(&lli->lli_agl_lock);
1116                         } while (sa_sent_full(sai) &&
1117                                  thread_is_running(sa_thread));
1118
1119                         sa_statahead(parent, name, namelen, &fid);
1120                 }
1121
1122                 pos = le64_to_cpu(dp->ldp_hash_end);
1123                 ll_release_page(dir, page,
1124                                 le32_to_cpu(dp->ldp_flags) & LDF_COLLIDE);
1125
1126                 if (sa_low_hit(sai)) {
1127                         rc = -EFAULT;
1128                         atomic_inc(&sbi->ll_sa_wrong);
1129                         CDEBUG(D_READA, "Statahead for dir "DFID" hit "
1130                                "ratio too low: hit/miss %llu/%llu"
1131                                ", sent/replied %llu/%llu, stopping "
1132                                "statahead thread: pid %d\n",
1133                                PFID(&lli->lli_fid), sai->sai_hit,
1134                                sai->sai_miss, sai->sai_sent,
1135                                sai->sai_replied, current_pid());
1136                         break;
1137                 }
1138         }
1139         ll_dir_chain_fini(&chain);
1140         ll_finish_md_op_data(op_data);
1141
1142         if (rc < 0) {
1143                 spin_lock(&lli->lli_sa_lock);
1144                 thread_set_flags(sa_thread, SVC_STOPPING);
1145                 lli->lli_sa_enabled = 0;
1146                 spin_unlock(&lli->lli_sa_lock);
1147         }
1148
1149         /* statahead is finished, but statahead entries need to be cached, wait
1150          * for file release to stop me. */
1151         while (thread_is_running(sa_thread)) {
1152                 l_wait_event(sa_thread->t_ctl_waitq,
1153                              sa_has_callback(sai) ||
1154                              !thread_is_running(sa_thread),
1155                              &lwi);
1156
1157                 sa_handle_callback(sai);
1158         }
1159
1160         EXIT;
1161 out:
1162         if (sai->sai_agl_valid) {
1163                 spin_lock(&lli->lli_agl_lock);
1164                 thread_set_flags(agl_thread, SVC_STOPPING);
1165                 spin_unlock(&lli->lli_agl_lock);
1166                 wake_up(&agl_thread->t_ctl_waitq);
1167
1168                 CDEBUG(D_READA, "stop agl thread: sai %p pid %u\n",
1169                        sai, (unsigned int)agl_thread->t_pid);
1170                 l_wait_event(agl_thread->t_ctl_waitq,
1171                              thread_is_stopped(agl_thread),
1172                              &lwi);
1173         } else {
1174                 /* Set agl_thread flags anyway. */
1175                 thread_set_flags(agl_thread, SVC_STOPPED);
1176         }
1177
1178         /* wait for inflight statahead RPCs to finish, and then we can free sai
1179          * safely because statahead RPC will access sai data */
1180         while (sai->sai_sent != sai->sai_replied) {
1181                 /* in case we're not woken up, timeout wait */
1182                 lwi = LWI_TIMEOUT(msecs_to_jiffies(MSEC_PER_SEC >> 3),
1183                                   NULL, NULL);
1184                 l_wait_event(sa_thread->t_ctl_waitq,
1185                         sai->sai_sent == sai->sai_replied, &lwi);
1186         }
1187
1188         /* release resources held by statahead RPCs */
1189         sa_handle_callback(sai);
1190
1191         spin_lock(&lli->lli_sa_lock);
1192         thread_set_flags(sa_thread, SVC_STOPPED);
1193         spin_unlock(&lli->lli_sa_lock);
1194
1195         CDEBUG(D_READA, "statahead thread stopped: sai %p, parent %.*s\n",
1196                sai, parent->d_name.len, parent->d_name.name);
1197
1198         wake_up(&sai->sai_waitq);
1199         wake_up(&sa_thread->t_ctl_waitq);
1200         ll_sai_put(sai);
1201
1202         return rc;
1203 }
1204
1205 /* authorize opened dir handle @key to statahead */
1206 void ll_authorize_statahead(struct inode *dir, void *key)
1207 {
1208         struct ll_inode_info *lli = ll_i2info(dir);
1209
1210         spin_lock(&lli->lli_sa_lock);
1211         if (lli->lli_opendir_key == NULL && lli->lli_sai == NULL) {
1212                 /*
1213                  * if lli_sai is not NULL, it means previous statahead is not
1214                  * finished yet, we'd better not start a new statahead for now.
1215                  */
1216                 LASSERT(lli->lli_opendir_pid == 0);
1217                 lli->lli_opendir_key = key;
1218                 lli->lli_opendir_pid = current_pid();
1219                 lli->lli_sa_enabled = 1;
1220         }
1221         spin_unlock(&lli->lli_sa_lock);
1222 }
1223
1224 /*
1225  * deauthorize opened dir handle @key to statahead, and notify statahead thread
1226  * to quit if it's running.
1227  */
1228 void ll_deauthorize_statahead(struct inode *dir, void *key)
1229 {
1230         struct ll_inode_info *lli = ll_i2info(dir);
1231         struct ll_statahead_info *sai;
1232
1233         LASSERT(lli->lli_opendir_key == key);
1234         LASSERT(lli->lli_opendir_pid != 0);
1235
1236         CDEBUG(D_READA, "deauthorize statahead for "DFID"\n",
1237                 PFID(&lli->lli_fid));
1238
1239         spin_lock(&lli->lli_sa_lock);
1240         lli->lli_opendir_key = NULL;
1241         lli->lli_opendir_pid = 0;
1242         lli->lli_sa_enabled = 0;
1243         sai = lli->lli_sai;
1244         if (sai != NULL && thread_is_running(&sai->sai_thread)) {
1245                 /*
1246                  * statahead thread may not quit yet because it needs to cache
1247                  * entries, now it's time to tell it to quit.
1248                  *
1249                  * In case sai is released, wake_up() is called inside spinlock,
1250                  * so we have to call smp_mb() explicitely to serialize ops.
1251                  */
1252                 thread_set_flags(&sai->sai_thread, SVC_STOPPING);
1253                 smp_mb();
1254                 wake_up(&sai->sai_thread.t_ctl_waitq);
1255         }
1256         spin_unlock(&lli->lli_sa_lock);
1257 }
1258
1259 enum {
1260         /**
1261          * not first dirent, or is "."
1262          */
1263         LS_NOT_FIRST_DE = 0,
1264         /**
1265          * the first non-hidden dirent
1266          */
1267         LS_FIRST_DE,
1268         /**
1269          * the first hidden dirent, that is "."
1270          */
1271         LS_FIRST_DOT_DE
1272 };
1273
1274 /* file is first dirent under @dir */
1275 static int is_first_dirent(struct inode *dir, struct dentry *dentry)
1276 {
1277         struct ll_dir_chain   chain;
1278         struct qstr          *target = &dentry->d_name;
1279         struct md_op_data    *op_data;
1280         int                   dot_de;
1281         struct page          *page = NULL;
1282         int                   rc = LS_NOT_FIRST_DE;
1283         __u64                 pos = 0;
1284         ENTRY;
1285
1286         op_data = ll_prep_md_op_data(NULL, dir, dir, NULL, 0, 0,
1287                                      LUSTRE_OPC_ANY, dir);
1288         if (IS_ERR(op_data))
1289                 RETURN(PTR_ERR(op_data));
1290         /**
1291          *FIXME choose the start offset of the readdir
1292          */
1293         op_data->op_max_pages = ll_i2sbi(dir)->ll_md_brw_pages;
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                 rc = PTR_ERR(task);
1592                 CERROR("can't start ll_sa thread, rc: %d\n", rc);
1593                 GOTO(out, rc);
1594         }
1595
1596         l_wait_event(thread->t_ctl_waitq,
1597                      thread_is_running(thread) || thread_is_stopped(thread),
1598                      &lwi);
1599         ll_sai_put(sai);
1600
1601         /*
1602          * We don't stat-ahead for the first dirent since we are already in
1603          * lookup.
1604          */
1605         RETURN(-EAGAIN);
1606
1607 out:
1608         /* once we start statahead thread failed, disable statahead so that
1609          * subsequent stat won't waste time to try it. */
1610         spin_lock(&lli->lli_sa_lock);
1611         lli->lli_sa_enabled = 0;
1612         lli->lli_sai = NULL;
1613         spin_unlock(&lli->lli_sa_lock);
1614
1615         if (sai != NULL)
1616                 ll_sai_free(sai);
1617
1618         RETURN(rc);
1619 }
1620
1621 /**
1622  * statahead entry function, this is called when client getattr on a file, it
1623  * will start statahead thread if this is the first dir entry, else revalidate
1624  * dentry from statahead cache.
1625  *
1626  * \param[in]  dir      parent directory
1627  * \param[out] dentryp  dentry to getattr
1628  * \param[in]  unplug   unplug statahead window only (normally for negative
1629  *                      dentry)
1630  * \retval              1 on success
1631  * \retval              0 revalidation from statahead cache failed, caller needs
1632  *                      to getattr from server directly
1633  * \retval              negative number on error, caller often ignores this and
1634  *                      then getattr from server
1635  */
1636 int ll_statahead(struct inode *dir, struct dentry **dentryp, bool unplug)
1637 {
1638         struct ll_statahead_info *sai;
1639
1640         sai = ll_sai_get(dir);
1641         if (sai != NULL) {
1642                 int rc;
1643
1644                 rc = revalidate_statahead_dentry(dir, sai, dentryp, unplug);
1645                 CDEBUG(D_READA, "revalidate statahead %.*s: %d.\n",
1646                         (*dentryp)->d_name.len, (*dentryp)->d_name.name, rc);
1647                 ll_sai_put(sai);
1648                 return rc;
1649         }
1650         return start_statahead_thread(dir, *dentryp);
1651 }