lustre/llite/statahead.c

   1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
   2  * vim:expandtab:shiftwidth=8:tabstop=8:
   3  *
   4  * GPL HEADER START
   5  *
   6  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 only,
  10  * as published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License version 2 for more details (a copy is included
  16  * in the LICENSE file that accompanied this code).
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * version 2 along with this program; If not, see
  20  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  21  *
  22  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  23  * CA 95054 USA or visit www.sun.com if you need additional information or
  24  * have any questions.
  25  *
  26  * GPL HEADER END
  27  */
  28 /*
  29  * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
  30  * Use is subject to license terms.
  31  *
  32  * Copyright (c) 2011 Whamcloud, Inc.
  33  *
  34  */
  35 /*
  36  * This file is part of Lustre, http://www.lustre.org/
  37  * Lustre is a trademark of Sun Microsystems, Inc.
  38  */
  39
  40 #include <linux/fs.h>
  41 #include <linux/sched.h>
  42 #include <linux/mm.h>
  43 #include <linux/smp_lock.h>
  44 #include <linux/highmem.h>
  45 #include <linux/pagemap.h>
  46
  47 #define DEBUG_SUBSYSTEM S_LLITE
  48
  49 #include <obd_support.h>
  50 #include <lustre_lite.h>
  51 #include <lustre_dlm.h>
  52 #include <linux/lustre_version.h>
  53 #include "llite_internal.h"
  54
  55 #define SA_OMITTED_ENTRY_MAX 8ULL
  56
  57 typedef enum {
  58         /** negative values are for error cases */
  59         SA_ENTRY_INIT = 0,      /** init entry */
  60         SA_ENTRY_SUCC = 1,      /** stat succeed */
  61         SA_ENTRY_INVA = 2,      /** invalid entry */
  62         SA_ENTRY_DEST = 3,      /** entry to be destroyed */
  63 } se_stat_t;
  64
  65 struct ll_sa_entry {
  66         /* link into sai->sai_entries_{sent,received,stated} */
  67         cfs_list_t              se_list;
  68         /* link into sai hash table locally */
  69         cfs_list_t              se_hash;
  70         /* entry reference count */
  71         cfs_atomic_t            se_refcount;
  72         /* entry index in the sai */
  73         __u64                   se_index;
  74         /* low layer ldlm lock handle */
  75         __u64                   se_handle;
  76         /* entry status */
  77         se_stat_t               se_stat;
  78         /* entry size, contains name */
  79         int                     se_size;
  80         /* pointer to async getattr enqueue info */
  81         struct md_enqueue_info *se_minfo;
  82         /* pointer to the async getattr request */
  83         struct ptlrpc_request  *se_req;
  84         /* pointer to the target inode */
  85         struct inode           *se_inode;
  86         /* entry name */
  87         struct qstr             se_qstr;
  88 };
  89
  90 static unsigned int sai_generation = 0;
  91 static cfs_spinlock_t sai_generation_lock = CFS_SPIN_LOCK_UNLOCKED;
  92
  93 static inline int ll_sa_entry_unlinked(struct ll_sa_entry *entry)
  94 {
  95         return cfs_list_empty(&entry->se_list);
  96 }
  97
  98 static inline int ll_sa_entry_unhashed(struct ll_sa_entry *entry)
  99 {
 100         return cfs_list_empty(&entry->se_hash);
 101 }
 102
 103 /*
 104  * The entry only can be released by the caller, it is necessary to hold lock.
 105  */
 106 static inline int ll_sa_entry_stated(struct ll_sa_entry *entry)
 107 {
 108         smp_rmb();
 109         return (entry->se_stat != SA_ENTRY_INIT);
 110 }
 111
 112 static inline int ll_sa_entry_hash(int val)
 113 {
 114         return val & LL_SA_CACHE_MASK;
 115 }
 116
 117 /*
 118  * Insert entry to hash SA table.
 119  */
 120 static inline void
 121 ll_sa_entry_enhash(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
 122 {
 123         int i = ll_sa_entry_hash(entry->se_qstr.hash);
 124
 125         cfs_spin_lock(&sai->sai_cache_lock[i]);
 126         cfs_list_add_tail(&entry->se_hash, &sai->sai_cache[i]);
 127         cfs_spin_unlock(&sai->sai_cache_lock[i]);
 128 }
 129
 130 /*
 131  * Remove entry from SA table.
 132  */
 133 static inline void
 134 ll_sa_entry_unhash(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
 135 {
 136         int i = ll_sa_entry_hash(entry->se_qstr.hash);
 137
 138         cfs_spin_lock(&sai->sai_cache_lock[i]);
 139         cfs_list_del_init(&entry->se_hash);
 140         cfs_spin_unlock(&sai->sai_cache_lock[i]);
 141 }
 142
 143 static inline int sa_received_empty(struct ll_statahead_info *sai)
 144 {
 145         return cfs_list_empty(&sai->sai_entries_received);
 146 }
 147
 148 static inline int sa_not_full(struct ll_statahead_info *sai)
 149 {
 150         return (cfs_atomic_read(&sai->sai_cache_count) < sai->sai_max);
 151 }
 152
 153 /**
 154  * (1) hit ratio less than 80%
 155  * or
 156  * (2) consecutive miss more than 8
 157  * then means low hit.
 158  */
 159 static inline int sa_low_hit(struct ll_statahead_info *sai)
 160 {
 161         return ((sai->sai_hit > 7 && sai->sai_hit < 4 * sai->sai_miss) ||
 162                 (sai->sai_consecutive_miss > 8));
 163 }
 164
 165 /*
 166  * If the given index is behind of statahead window more than
 167  * SA_OMITTED_ENTRY_MAX, then it is old.
 168  */
 169 static inline int is_omitted_entry(struct ll_statahead_info *sai, __u64 index)
 170 {
 171         return ((__u64)sai->sai_max + index + SA_OMITTED_ENTRY_MAX <
 172                  sai->sai_index);
 173 }
 174
 175 /*
 176  * Insert it into sai_entries_sent tail when init.
 177  */
 178 static struct ll_sa_entry *
 179 ll_sa_entry_alloc(struct ll_statahead_info *sai, __u64 index,
 180                   const char *name, int len)
 181 {
 182         struct ll_inode_info *lli;
 183         struct ll_sa_entry   *entry;
 184         int                   entry_size;
 185         char                 *dname;
 186         ENTRY;
 187
 188         entry_size = sizeof(struct ll_sa_entry) + (len & ~3) + 4;
 189         OBD_ALLOC(entry, entry_size);
 190         if (unlikely(entry == NULL))
 191                 RETURN(ERR_PTR(-ENOMEM));
 192
 193         CDEBUG(D_READA, "alloc sai entry %.*s(%p) index "LPU64"\n",
 194                len, name, entry, index);
 195
 196         entry->se_index = index;
 197
 198         /*
 199          * Statahead entry reference rules:
 200          *
 201          * 1) When statahead entry is initialized, its reference is set as 2.
 202          *    One reference is used by the directory scanner. When the scanner
 203          *    searches the statahead cache for the given name, it can perform
 204          *    lockless hash lookup (only the scanner can remove entry from hash
 205          *    list), and once found, it needn't to call "atomic_inc()" for the
 206          *    entry reference. So the performance is improved. After using the
 207          *    statahead entry, the scanner will call "atomic_dec()" to drop the
 208          *    reference held when initialization. If it is the last reference,
 209          *    the statahead entry will be freed.
 210          *
 211          * 2) All other threads, including statahead thread and ptlrpcd thread,
 212          *    when they process the statahead entry, the reference for target
 213          *    should be held to guarantee the entry will not be released by the
 214          *    directory scanner. After processing the entry, these threads will
 215          *    drop the entry reference. If it is the last reference, the entry
 216          *    will be freed.
 217          *
 218          *    The second reference when initializes the statahead entry is used
 219          *    by the statahead thread, following the rule 2).
 220          */
 221         cfs_atomic_set(&entry->se_refcount, 2);
 222         entry->se_stat = SA_ENTRY_INIT;
 223         entry->se_size = entry_size;
 224         dname = (char *)entry + sizeof(struct ll_sa_entry);
 225         memcpy(dname, name, len);
 226         dname[len] = 0;
 227         entry->se_qstr.hash = full_name_hash(name, len);
 228         entry->se_qstr.len = len;
 229         entry->se_qstr.name = dname;
 230
 231         lli = ll_i2info(sai->sai_inode);
 232         cfs_spin_lock(&lli->lli_sa_lock);
 233         cfs_list_add_tail(&entry->se_list, &sai->sai_entries_sent);
 234         cfs_spin_unlock(&lli->lli_sa_lock);
 235
 236         cfs_atomic_inc(&sai->sai_cache_count);
 237         ll_sa_entry_enhash(sai, entry);
 238
 239         RETURN(entry);
 240 }
 241
 242 /*
 243  * Used by the directory scanner to search entry with name.
 244  *
 245  * Only the caller can remove the entry from hash, so it is unnecessary to hold
 246  * hash lock. It is caller's duty to release the init refcount on the entry, so
 247  * it is also unnecessary to increase refcount on the entry.
 248  */
 249 static struct ll_sa_entry *
 250 ll_sa_entry_get_byname(struct ll_statahead_info *sai, const struct qstr *qstr)
 251 {
 252         struct ll_sa_entry *entry;
 253         int i = ll_sa_entry_hash(qstr->hash);
 254
 255         cfs_list_for_each_entry(entry, &sai->sai_cache[i], se_hash) {
 256                 if (entry->se_qstr.hash == qstr->hash &&
 257                     entry->se_qstr.len == qstr->len &&
 258                     memcmp(entry->se_qstr.name, qstr->name, qstr->len) == 0)
 259                         return entry;
 260         }
 261         return NULL;
 262 }
 263
 264 /*
 265  * Used by the async getattr request callback to find entry with index.
 266  *
 267  * Inside lli_sa_lock to prevent others to change the list during the search.
 268  * It needs to increase entry refcount before returning to guarantee that the
 269  * entry cannot be freed by others.
 270  */
 271 static struct ll_sa_entry *
 272 ll_sa_entry_get_byindex(struct ll_statahead_info *sai, __u64 index)
 273 {
 274         struct ll_sa_entry *entry;
 275
 276         cfs_list_for_each_entry(entry, &sai->sai_entries_sent, se_list) {
 277                 if (entry->se_index == index) {
 278                         cfs_atomic_inc(&entry->se_refcount);
 279                         return entry;
 280                 }
 281                 if (entry->se_index > index)
 282                         break;
 283         }
 284         return NULL;
 285 }
 286
 287 static void ll_sa_entry_cleanup(struct ll_statahead_info *sai,
 288                                  struct ll_sa_entry *entry)
 289 {
 290         struct md_enqueue_info *minfo = entry->se_minfo;
 291         struct ptlrpc_request  *req   = entry->se_req;
 292
 293         if (minfo) {
 294                 entry->se_minfo = NULL;
 295                 ll_intent_release(&minfo->mi_it);
 296                 iput(minfo->mi_dir);
 297                 OBD_FREE_PTR(minfo);
 298         }
 299
 300         if (req) {
 301                 entry->se_req = NULL;
 302                 ptlrpc_req_finished(req);
 303         }
 304 }
 305
 306 static void ll_sa_entry_put(struct ll_statahead_info *sai,
 307                              struct ll_sa_entry *entry)
 308 {
 309         if (cfs_atomic_dec_and_test(&entry->se_refcount)) {
 310                 CDEBUG(D_READA, "free sai entry %.*s(%p) index "LPU64"\n",
 311                        entry->se_qstr.len, entry->se_qstr.name, entry,
 312                        entry->se_index);
 313
 314                 LASSERT(ll_sa_entry_unhashed(entry));
 315                 LASSERT(ll_sa_entry_unlinked(entry));
 316
 317                 ll_sa_entry_cleanup(sai, entry);
 318                 if (entry->se_inode)
 319                         iput(entry->se_inode);
 320
 321                 OBD_FREE(entry, entry->se_size);
 322                 cfs_atomic_dec(&sai->sai_cache_count);
 323         }
 324 }
 325
 326 static inline void
 327 do_sai_entry_fini(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
 328 {
 329         struct ll_inode_info *lli = ll_i2info(sai->sai_inode);
 330
 331         ll_sa_entry_unhash(sai, entry);
 332
 333         cfs_spin_lock(&lli->lli_sa_lock);
 334         entry->se_stat = SA_ENTRY_DEST;
 335         if (likely(!ll_sa_entry_unlinked(entry)))
 336                 cfs_list_del_init(&entry->se_list);
 337         cfs_spin_unlock(&lli->lli_sa_lock);
 338
 339         ll_sa_entry_put(sai, entry);
 340 }
 341
 342 /*
 343  * Delete it from sai_entries_stated list when fini.
 344  */
 345 static void
 346 ll_sa_entry_fini(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
 347 {
 348         struct ll_sa_entry *pos, *next;
 349
 350         if (entry)
 351                 do_sai_entry_fini(sai, entry);
 352
 353         /* drop old entry from sent list */
 354         cfs_list_for_each_entry_safe(pos, next, &sai->sai_entries_sent,
 355                                      se_list) {
 356                 if (is_omitted_entry(sai, pos->se_index))
 357                         do_sai_entry_fini(sai, pos);
 358                 else
 359                         break;
 360         }
 361
 362         /* drop old entry from stated list */
 363         cfs_list_for_each_entry_safe(pos, next, &sai->sai_entries_stated,
 364                                      se_list) {
 365                 if (is_omitted_entry(sai, pos->se_index))
 366                         do_sai_entry_fini(sai, pos);
 367                 else
 368                         break;
 369         }
 370 }
 371
 372 /*
 373  * Inside lli_sa_lock.
 374  */
 375 static void
 376 do_sai_entry_to_stated(struct ll_statahead_info *sai,
 377                        struct ll_sa_entry *entry, int rc)
 378 {
 379         struct ll_sa_entry *se;
 380         cfs_list_t         *pos = &sai->sai_entries_stated;
 381
 382         if (!ll_sa_entry_unlinked(entry))
 383                 cfs_list_del_init(&entry->se_list);
 384
 385         cfs_list_for_each_entry_reverse(se, &sai->sai_entries_stated, se_list) {
 386                 if (se->se_index < entry->se_index) {
 387                         pos = &se->se_list;
 388                         break;
 389                 }
 390         }
 391
 392         cfs_list_add(&entry->se_list, pos);
 393         entry->se_stat = rc;
 394 }
 395
 396 /*
 397  * Move entry to sai_entries_stated and sort with the index.
 398  * \retval 1    -- entry to be destroyed.
 399  * \retval 0    -- entry is inserted into stated list.
 400  */
 401 static int
 402 ll_sa_entry_to_stated(struct ll_statahead_info *sai,
 403                        struct ll_sa_entry *entry, int rc)
 404 {
 405         struct ll_inode_info *lli = ll_i2info(sai->sai_inode);
 406         int                   ret = 1;
 407
 408         ll_sa_entry_cleanup(sai, entry);
 409
 410         cfs_spin_lock(&lli->lli_sa_lock);
 411         if (likely(entry->se_stat != SA_ENTRY_DEST)) {
 412                 do_sai_entry_to_stated(sai, entry, rc);
 413                 ret = 0;
 414         }
 415         cfs_spin_unlock(&lli->lli_sa_lock);
 416
 417         return ret;
 418 }
 419
 420 static struct ll_statahead_info *ll_sai_alloc(void)
 421 {
 422         struct ll_statahead_info *sai;
 423         int                       i;
 424         ENTRY;
 425
 426         OBD_ALLOC_PTR(sai);
 427         if (!sai)
 428                 RETURN(NULL);
 429
 430         cfs_atomic_set(&sai->sai_refcount, 1);
 431         cfs_spin_lock(&sai_generation_lock);
 432         sai->sai_generation = ++sai_generation;
 433         if (unlikely(sai_generation == 0))
 434                 sai->sai_generation = ++sai_generation;
 435         cfs_spin_unlock(&sai_generation_lock);
 436         sai->sai_max = LL_SA_RPC_MIN;
 437         cfs_waitq_init(&sai->sai_waitq);
 438         cfs_waitq_init(&sai->sai_thread.t_ctl_waitq);
 439         CFS_INIT_LIST_HEAD(&sai->sai_entries_sent);
 440         CFS_INIT_LIST_HEAD(&sai->sai_entries_received);
 441         CFS_INIT_LIST_HEAD(&sai->sai_entries_stated);
 442         for (i = 0; i < LL_SA_CACHE_SIZE; i++) {
 443                 CFS_INIT_LIST_HEAD(&sai->sai_cache[i]);
 444                 cfs_spin_lock_init(&sai->sai_cache_lock[i]);
 445         }
 446         cfs_atomic_set(&sai->sai_cache_count, 0);
 447
 448         RETURN(sai);
 449 }
 450
 451 static inline struct ll_statahead_info *
 452 ll_sai_get(struct ll_statahead_info *sai)
 453 {
 454         cfs_atomic_inc(&sai->sai_refcount);
 455         return sai;
 456 }
 457
 458 static void ll_sai_put(struct ll_statahead_info *sai)
 459 {
 460         struct inode         *inode = sai->sai_inode;
 461         struct ll_inode_info *lli   = ll_i2info(inode);
 462         ENTRY;
 463
 464         if (cfs_atomic_dec_and_lock(&sai->sai_refcount, &lli->lli_sa_lock)) {
 465                 struct ll_sa_entry *entry, *next;
 466
 467                 if (unlikely(cfs_atomic_read(&sai->sai_refcount) > 0)) {
 468                         /* It is race case, the interpret callback just hold
 469                          * a reference count */
 470                         cfs_spin_unlock(&lli->lli_sa_lock);
 471                         RETURN_EXIT;
 472                 }
 473
 474                 LASSERT(lli->lli_opendir_key == NULL);
 475                 lli->lli_sai = NULL;
 476                 lli->lli_opendir_pid = 0;
 477                 cfs_spin_unlock(&lli->lli_sa_lock);
 478
 479                 LASSERT(thread_is_stopped(&sai->sai_thread));
 480
 481                 if (sai->sai_sent > sai->sai_replied)
 482                         CDEBUG(D_READA,"statahead for dir "DFID" does not "
 483                               "finish: [sent:"LPU64"] [replied:"LPU64"]\n",
 484                               PFID(&lli->lli_fid),
 485                               sai->sai_sent, sai->sai_replied);
 486
 487                 cfs_list_for_each_entry_safe(entry, next,
 488                                              &sai->sai_entries_sent, se_list)
 489                         do_sai_entry_fini(sai, entry);
 490
 491                 LASSERT(sa_received_empty(sai));
 492
 493                 cfs_list_for_each_entry_safe(entry, next,
 494                                              &sai->sai_entries_stated, se_list)
 495                         do_sai_entry_fini(sai, entry);
 496
 497                 LASSERT(cfs_atomic_read(&sai->sai_cache_count) == 0);
 498
 499                 iput(inode);
 500                 OBD_FREE_PTR(sai);
 501         }
 502
 503         EXIT;
 504 }
 505
 506 static void do_statahead_interpret(struct ll_statahead_info *sai,
 507                                    struct ll_sa_entry *target)
 508 {
 509         struct inode           *dir   = sai->sai_inode;
 510         struct inode           *child;
 511         struct ll_inode_info   *lli   = ll_i2info(dir);
 512         struct ll_sa_entry     *entry;
 513         struct md_enqueue_info *minfo;
 514         struct lookup_intent   *it;
 515         struct ptlrpc_request  *req;
 516         struct mdt_body        *body;
 517         int                     rc    = 0;
 518         ENTRY;
 519
 520         cfs_spin_lock(&lli->lli_sa_lock);
 521         if (target != NULL && target->se_req != NULL &&
 522             !cfs_list_empty(&target->se_list)) {
 523                 entry = target;
 524         } else if (unlikely(sa_received_empty(sai))) {
 525                 cfs_spin_unlock(&lli->lli_sa_lock);
 526                 RETURN_EXIT;
 527         } else {
 528                 entry = cfs_list_entry(sai->sai_entries_received.next,
 529                                        struct ll_sa_entry, se_list);
 530         }
 531
 532         cfs_atomic_inc(&entry->se_refcount);
 533         cfs_list_del_init(&entry->se_list);
 534         cfs_spin_unlock(&lli->lli_sa_lock);
 535
 536         LASSERT(entry->se_handle != 0);
 537
 538         minfo = entry->se_minfo;
 539         it = &minfo->mi_it;
 540         req = entry->se_req;
 541         body = req_capsule_server_get(&req->rq_pill, &RMF_MDT_BODY);
 542         if (body == NULL)
 543                 GOTO(out, rc = -EFAULT);
 544
 545         child = entry->se_inode;
 546         if (child == NULL) {
 547                 /*
 548                  * lookup.
 549                  */
 550                 LASSERT(fid_is_zero(&minfo->mi_data.op_fid2));
 551
 552                 /* XXX: No fid in reply, this is probaly cross-ref case.
 553                  * SA can't handle it yet. */
 554                 if (body->valid & OBD_MD_MDS)
 555                         GOTO(out, rc = -EAGAIN);
 556         } else {
 557                 /*
 558                  * revalidate.
 559                  */
 560                 /* unlinked and re-created with the same name */
 561                 if (unlikely(!lu_fid_eq(&minfo->mi_data.op_fid2, &body->fid1))){
 562                         entry->se_inode = NULL;
 563                         iput(child);
 564                         child = NULL;
 565                 }
 566         }
 567
 568         it->d.lustre.it_lock_handle = entry->se_handle;
 569         rc = md_revalidate_lock(ll_i2mdexp(dir), it, NULL, NULL);
 570         if (rc != 1)
 571                 GOTO(out, rc = -EAGAIN);
 572
 573         rc = ll_prep_inode(&child, req, dir->i_sb);
 574         if (rc)
 575                 GOTO(out, rc);
 576
 577         CDEBUG(D_DLMTRACE, "setting l_data to inode %p (%lu/%u)\n",
 578                child, child->i_ino, child->i_generation);
 579         ll_set_lock_data(ll_i2sbi(dir)->ll_md_exp, child, it, NULL);
 580
 581         entry->se_inode = child;
 582
 583         EXIT;
 584
 585 out:
 586         /* The "ll_sa_entry_to_stated()" will drop related ldlm ibits lock
 587          * reference count by calling "ll_intent_drop_lock()" in spite of the
 588          * above operations failed or not. Do not worry about calling
 589          * "ll_intent_drop_lock()" more than once. */
 590         rc = ll_sa_entry_to_stated(sai, entry, rc < 0 ? rc : SA_ENTRY_SUCC);
 591         if (rc == 0 && entry->se_index == sai->sai_index_wait && target == NULL)
 592                 cfs_waitq_signal(&sai->sai_waitq);
 593         ll_sa_entry_put(sai, entry);
 594 }
 595
 596 static int ll_statahead_interpret(struct ptlrpc_request *req,
 597                                   struct md_enqueue_info *minfo, int rc)
 598 {
 599         struct lookup_intent     *it  = &minfo->mi_it;
 600         struct inode             *dir = minfo->mi_dir;
 601         struct ll_inode_info     *lli = ll_i2info(dir);
 602         struct ll_statahead_info *sai = NULL;
 603         struct ll_sa_entry       *entry;
 604         int                       wakeup;
 605         ENTRY;
 606
 607         if (it_disposition(it, DISP_LOOKUP_NEG))
 608                 rc = -ENOENT;
 609
 610         cfs_spin_lock(&lli->lli_sa_lock);
 611         /* stale entry */
 612         if (unlikely(lli->lli_sai == NULL ||
 613                      lli->lli_sai->sai_generation != minfo->mi_generation)) {
 614                 cfs_spin_unlock(&lli->lli_sa_lock);
 615                 GOTO(out, rc = -ESTALE);
 616         } else {
 617                 sai = ll_sai_get(lli->lli_sai);
 618                 if (unlikely(!thread_is_running(&sai->sai_thread))) {
 619                         sai->sai_replied++;
 620                         cfs_spin_unlock(&lli->lli_sa_lock);
 621                         GOTO(out, rc = -EBADFD);
 622                 }
 623
 624                 entry = ll_sa_entry_get_byindex(sai, minfo->mi_cbdata);
 625                 if (entry == NULL) {
 626                         sai->sai_replied++;
 627                         cfs_spin_unlock(&lli->lli_sa_lock);
 628                         GOTO(out, rc = -EIDRM);
 629                 }
 630
 631                 cfs_list_del_init(&entry->se_list);
 632                 if (rc != 0) {
 633                         sai->sai_replied++;
 634                         do_sai_entry_to_stated(sai, entry, rc);
 635                         cfs_spin_unlock(&lli->lli_sa_lock);
 636                         if (entry->se_index == sai->sai_index_wait)
 637                                 cfs_waitq_signal(&sai->sai_waitq);
 638                 } else {
 639                         entry->se_minfo = minfo;
 640                         entry->se_req = ptlrpc_request_addref(req);
 641                         /* Release the async ibits lock ASAP to avoid deadlock
 642                          * when statahead thread tries to enqueue lock on parent
 643                          * for readpage and other tries to enqueue lock on child
 644                          * with parent's lock held, for example: unlink. */
 645                         entry->se_handle = it->d.lustre.it_lock_handle;
 646                         ll_intent_drop_lock(it);
 647                         wakeup = sa_received_empty(sai);
 648                         cfs_list_add_tail(&entry->se_list,
 649                                           &sai->sai_entries_received);
 650                         sai->sai_replied++;
 651                         cfs_spin_unlock(&lli->lli_sa_lock);
 652                         if (wakeup)
 653                                 cfs_waitq_signal(&sai->sai_thread.t_ctl_waitq);
 654                 }
 655                 ll_sa_entry_put(sai, entry);
 656         }
 657
 658         EXIT;
 659
 660 out:
 661         if (rc != 0) {
 662                 ll_intent_release(it);
 663                 iput(dir);
 664                 OBD_FREE_PTR(minfo);
 665         }
 666         if (sai != NULL)
 667                 ll_sai_put(sai);
 668         return rc;
 669 }
 670
 671 static void sa_args_fini(struct md_enqueue_info *minfo,
 672                          struct ldlm_enqueue_info *einfo)
 673 {
 674         LASSERT(minfo && einfo);
 675         iput(minfo->mi_dir);
 676         capa_put(minfo->mi_data.op_capa1);
 677         capa_put(minfo->mi_data.op_capa2);
 678         OBD_FREE_PTR(minfo);
 679         OBD_FREE_PTR(einfo);
 680 }
 681
 682 /**
 683  * There is race condition between "capa_put" and "ll_statahead_interpret" for
 684  * accessing "op_data.op_capa[1,2]" as following:
 685  * "capa_put" releases "op_data.op_capa[1,2]"'s reference count after calling
 686  * "md_intent_getattr_async". But "ll_statahead_interpret" maybe run first, and
 687  * fill "op_data.op_capa[1,2]" as POISON, then cause "capa_put" access invalid
 688  * "ocapa". So here reserve "op_data.op_capa[1,2]" in "pcapa" before calling
 689  * "md_intent_getattr_async".
 690  */
 691 static int sa_args_init(struct inode *dir, struct inode *child,
 692                         struct qstr *qstr, struct md_enqueue_info **pmi,
 693                         struct ldlm_enqueue_info **pei,
 694                         struct obd_capa **pcapa)
 695 {
 696         struct ll_inode_info     *lli = ll_i2info(dir);
 697         struct md_enqueue_info   *minfo;
 698         struct ldlm_enqueue_info *einfo;
 699         struct md_op_data        *op_data;
 700
 701         OBD_ALLOC_PTR(einfo);
 702         if (einfo == NULL)
 703                 return -ENOMEM;
 704
 705         OBD_ALLOC_PTR(minfo);
 706         if (minfo == NULL) {
 707                 OBD_FREE_PTR(einfo);
 708                 return -ENOMEM;
 709         }
 710
 711         op_data = ll_prep_md_op_data(&minfo->mi_data, dir, child, qstr->name,
 712                                      qstr->len, 0, LUSTRE_OPC_ANY, NULL);
 713         if (IS_ERR(op_data)) {
 714                 OBD_FREE_PTR(einfo);
 715                 OBD_FREE_PTR(minfo);
 716                 return PTR_ERR(op_data);
 717         }
 718
 719         minfo->mi_it.it_op = IT_GETATTR;
 720         minfo->mi_dir = igrab(dir);
 721         minfo->mi_cb = ll_statahead_interpret;
 722         minfo->mi_generation = lli->lli_sai->sai_generation;
 723         minfo->mi_cbdata = lli->lli_sai->sai_index;
 724
 725         einfo->ei_type   = LDLM_IBITS;
 726         einfo->ei_mode   = it_to_lock_mode(&minfo->mi_it);
 727         einfo->ei_cb_bl  = ll_md_blocking_ast;
 728         einfo->ei_cb_cp  = ldlm_completion_ast;
 729         einfo->ei_cb_gl  = NULL;
 730         einfo->ei_cbdata = NULL;
 731
 732         *pmi = minfo;
 733         *pei = einfo;
 734         pcapa[0] = op_data->op_capa1;
 735         pcapa[1] = op_data->op_capa2;
 736
 737         return 0;
 738 }
 739
 740 static int do_sa_lookup(struct inode *dir, struct ll_sa_entry *entry)
 741 {
 742         struct md_enqueue_info   *minfo;
 743         struct ldlm_enqueue_info *einfo;
 744         struct obd_capa          *capas[2];
 745         int                       rc;
 746         ENTRY;
 747
 748         rc = sa_args_init(dir, NULL, &entry->se_qstr, &minfo, &einfo, capas);
 749         if (rc)
 750                 RETURN(rc);
 751
 752         rc = md_intent_getattr_async(ll_i2mdexp(dir), minfo, einfo);
 753         if (!rc) {
 754                 capa_put(capas[0]);
 755                 capa_put(capas[1]);
 756         } else {
 757                 sa_args_fini(minfo, einfo);
 758         }
 759
 760         RETURN(rc);
 761 }
 762
 763 /**
 764  * similar to ll_revalidate_it().
 765  * \retval      1 -- dentry valid
 766  * \retval      0 -- will send stat-ahead request
 767  * \retval others -- prepare stat-ahead request failed
 768  */
 769 static int do_sa_revalidate(struct inode *dir, struct ll_sa_entry *entry,
 770                             struct dentry *dentry)
 771 {
 772         struct inode             *inode = dentry->d_inode;
 773         struct lookup_intent      it = { .it_op = IT_GETATTR,
 774                                          .d.lustre.it_lock_handle = 0 };
 775         struct md_enqueue_info   *minfo;
 776         struct ldlm_enqueue_info *einfo;
 777         struct obd_capa          *capas[2];
 778         int rc;
 779         ENTRY;
 780
 781         if (unlikely(inode == NULL))
 782                 RETURN(1);
 783
 784         if (d_mountpoint(dentry))
 785                 RETURN(1);
 786
 787         if (unlikely(dentry == dentry->d_sb->s_root))
 788                 RETURN(1);
 789
 790         entry->se_inode = igrab(inode);
 791         rc = md_revalidate_lock(ll_i2mdexp(dir), &it, ll_inode2fid(inode),NULL);
 792         if (rc == 1) {
 793                 entry->se_handle = it.d.lustre.it_lock_handle;
 794                 ll_intent_release(&it);
 795                 RETURN(1);
 796         }
 797
 798         rc = sa_args_init(dir, inode, &entry->se_qstr, &minfo, &einfo, capas);
 799         if (rc) {
 800                 entry->se_inode = NULL;
 801                 iput(inode);
 802                 RETURN(rc);
 803         }
 804
 805         rc = md_intent_getattr_async(ll_i2mdexp(dir), minfo, einfo);
 806         if (!rc) {
 807                 capa_put(capas[0]);
 808                 capa_put(capas[1]);
 809         } else {
 810                 entry->se_inode = NULL;
 811                 iput(inode);
 812                 sa_args_fini(minfo, einfo);
 813         }
 814
 815         RETURN(rc);
 816 }
 817
 818 static void ll_statahead_one(struct dentry *parent, const char* entry_name,
 819                              int entry_name_len)
 820 {
 821         struct inode             *dir = parent->d_inode;
 822         struct ll_inode_info     *lli = ll_i2info(dir);
 823         struct ll_statahead_info *sai = lli->lli_sai;
 824         struct dentry            *dentry = NULL;
 825         struct ll_sa_entry       *entry;
 826         int                       rc;
 827         int                       rc1;
 828         ENTRY;
 829
 830         entry = ll_sa_entry_alloc(sai, sai->sai_index, entry_name,
 831                                   entry_name_len);
 832         if (IS_ERR(entry))
 833                 RETURN_EXIT;
 834
 835         dentry = d_lookup(parent, &entry->se_qstr);
 836         if (!dentry)
 837                 rc = do_sa_lookup(dir, entry);
 838         else
 839                 rc = do_sa_revalidate(dir, entry, dentry);
 840
 841         if (dentry != NULL)
 842                 dput(dentry);
 843
 844         if (rc) {
 845                 rc1 = ll_sa_entry_to_stated(sai, entry,
 846                                         rc < 0 ? SA_ENTRY_INVA : SA_ENTRY_SUCC);
 847                 if (rc1 == 0 && entry->se_index == sai->sai_index_wait)
 848                         cfs_waitq_signal(&sai->sai_waitq);
 849         } else {
 850                 sai->sai_sent++;
 851         }
 852
 853         sai->sai_index++;
 854         /* drop one refcount on entry by ll_sa_entry_alloc */
 855         ll_sa_entry_put(sai, entry);
 856
 857         EXIT;
 858 }
 859
 860 static int ll_statahead_thread(void *arg)
 861 {
 862         struct dentry            *parent = (struct dentry *)arg;
 863         struct inode             *dir = parent->d_inode;
 864         struct ll_inode_info     *lli = ll_i2info(dir);
 865         struct ll_sb_info        *sbi = ll_i2sbi(dir);
 866         struct ll_statahead_info *sai = ll_sai_get(lli->lli_sai);
 867         struct ptlrpc_thread     *thread = &sai->sai_thread;
 868         struct page              *page;
 869         __u64                     pos = 0;
 870         int                       first = 0;
 871         int                       rc = 0;
 872         struct ll_dir_chain       chain;
 873         ENTRY;
 874
 875         {
 876                 char pname[16];
 877                 snprintf(pname, 15, "ll_sa_%u", lli->lli_opendir_pid);
 878                 cfs_daemonize(pname);
 879         }
 880
 881         atomic_inc(&sbi->ll_sa_total);
 882         cfs_spin_lock(&lli->lli_sa_lock);
 883         thread_set_flags(thread, SVC_RUNNING);
 884         cfs_spin_unlock(&lli->lli_sa_lock);
 885         cfs_waitq_signal(&thread->t_ctl_waitq);
 886         CDEBUG(D_READA, "start doing statahead for %s\n", parent->d_name.name);
 887
 888         lli->lli_sa_pos = 0;
 889         ll_dir_chain_init(&chain);
 890         page = ll_get_dir_page(NULL, dir, pos, &chain);
 891
 892         while (1) {
 893                 struct l_wait_info lwi = { 0 };
 894                 struct lu_dirpage *dp;
 895                 struct lu_dirent  *ent;
 896
 897                 if (IS_ERR(page)) {
 898                         rc = PTR_ERR(page);
 899                         CDEBUG(D_READA, "error reading dir "DFID" at "LPU64
 900                                "/"LPU64": [rc %d] [parent %u]\n",
 901                                PFID(ll_inode2fid(dir)), pos, sai->sai_index,
 902                                rc, lli->lli_opendir_pid);
 903                         GOTO(out, rc);
 904                 }
 905
 906                 dp = page_address(page);
 907                 for (ent = lu_dirent_start(dp); ent != NULL;
 908                      ent = lu_dirent_next(ent)) {
 909                         __u64 hash;
 910                         int namelen;
 911                         char *name;
 912
 913                         hash = le64_to_cpu(ent->lde_hash);
 914                         if (unlikely(hash < pos))
 915                                 /*
 916                                  * Skip until we find target hash value.
 917                                  */
 918                                 continue;
 919
 920                         namelen = le16_to_cpu(ent->lde_namelen);
 921                         if (unlikely(namelen == 0))
 922                                 /*
 923                                  * Skip dummy record.
 924                                  */
 925                                 continue;
 926
 927                         name = ent->lde_name;
 928                         if (name[0] == '.') {
 929                                 if (namelen == 1) {
 930                                         /*
 931                                          * skip "."
 932                                          */
 933                                         continue;
 934                                 } else if (name[1] == '.' && namelen == 2) {
 935                                         /*
 936                                          * skip ".."
 937                                          */
 938                                         continue;
 939                                 } else if (!sai->sai_ls_all) {
 940                                         /*
 941                                          * skip hidden files.
 942                                          */
 943                                         sai->sai_skip_hidden++;
 944                                         continue;
 945                                 }
 946                         }
 947
 948                         /*
 949                          * don't stat-ahead first entry.
 950                          */
 951                         if (unlikely(++first == 1))
 952                                 continue;
 953
 954 keep_de:
 955                         l_wait_event(thread->t_ctl_waitq,
 956                                      sa_not_full(sai) ||
 957                                      !sa_received_empty(sai) ||
 958                                      !thread_is_running(thread),
 959                                      &lwi);
 960
 961                         while (!sa_received_empty(sai))
 962                                 do_statahead_interpret(sai, NULL);
 963
 964                         if (unlikely(!thread_is_running(thread))) {
 965                                 ll_release_page(page, 0);
 966                                 GOTO(out, rc);
 967                         }
 968
 969                         if (!sa_not_full(sai))
 970                                 /*
 971                                  * do not skip the current de.
 972                                  */
 973                                 goto keep_de;
 974
 975                         ll_statahead_one(parent, name, namelen);
 976                 }
 977                 pos = le64_to_cpu(dp->ldp_hash_end);
 978                 if (pos == MDS_DIR_END_OFF) {
 979                         /*
 980                          * End of directory reached.
 981                          */
 982                         ll_release_page(page, 0);
 983                         while (1) {
 984                                 l_wait_event(thread->t_ctl_waitq,
 985                                              !sa_received_empty(sai) ||
 986                                              sai->sai_sent == sai->sai_replied||
 987                                              !thread_is_running(thread),
 988                                              &lwi);
 989
 990                                 while (!sa_received_empty(sai))
 991                                         do_statahead_interpret(sai, NULL);
 992
 993                                 if ((sai->sai_sent == sai->sai_replied &&
 994                                      sa_received_empty(sai)) ||
 995                                     !thread_is_running(thread))
 996                                         GOTO(out, rc = 0);
 997                         }
 998                 } else if (1) {
 999                         /*
1000                          * chain is exhausted.
1001                          * Normal case: continue to the next page.
1002                          */
1003                         ll_release_page(page, le32_to_cpu(dp->ldp_flags) &
1004                                               LDF_COLLIDE);
1005                         lli->lli_sa_pos = pos;
1006                         sai->sai_in_readpage = 1;
1007                         page = ll_get_dir_page(NULL, dir, pos, &chain);
1008                         sai->sai_in_readpage = 0;
1009                 } else {
1010                         LASSERT(le32_to_cpu(dp->ldp_flags) & LDF_COLLIDE);
1011                         ll_release_page(page, 1);
1012                         /*
1013                          * go into overflow page.
1014                          */
1015                 }
1016         }
1017         EXIT;
1018
1019 out:
1020         ll_dir_chain_fini(&chain);
1021         cfs_spin_lock(&lli->lli_sa_lock);
1022         if (!sa_received_empty(sai)) {
1023                 thread_set_flags(thread, SVC_STOPPING);
1024                 cfs_spin_unlock(&lli->lli_sa_lock);
1025
1026                 /* To release the resources held by received entries. */
1027                 while (!sa_received_empty(sai))
1028                         do_statahead_interpret(sai, NULL);
1029
1030                 cfs_spin_lock(&lli->lli_sa_lock);
1031         }
1032         thread_set_flags(thread, SVC_STOPPED);
1033         cfs_spin_unlock(&lli->lli_sa_lock);
1034         cfs_waitq_signal(&sai->sai_waitq);
1035         cfs_waitq_signal(&thread->t_ctl_waitq);
1036         ll_sai_put(sai);
1037         dput(parent);
1038         CDEBUG(D_READA, "statahead thread stopped, pid %d\n",
1039                cfs_curproc_pid());
1040         return rc;
1041 }
1042
1043 /**
1044  * called in ll_file_release().
1045  */
1046 void ll_stop_statahead(struct inode *dir, void *key)
1047 {
1048         struct ll_inode_info *lli = ll_i2info(dir);
1049
1050         if (unlikely(key == NULL))
1051                 return;
1052
1053         cfs_spin_lock(&lli->lli_sa_lock);
1054         if (lli->lli_opendir_key != key || lli->lli_opendir_pid == 0) {
1055                 cfs_spin_unlock(&lli->lli_sa_lock);
1056                 return;
1057         }
1058
1059         lli->lli_opendir_key = NULL;
1060
1061         if (lli->lli_sai) {
1062                 struct l_wait_info lwi = { 0 };
1063                 struct ptlrpc_thread *thread = &lli->lli_sai->sai_thread;
1064
1065                 if (!thread_is_stopped(thread)) {
1066                         thread_set_flags(thread, SVC_STOPPING);
1067                         cfs_spin_unlock(&lli->lli_sa_lock);
1068                         cfs_waitq_signal(&thread->t_ctl_waitq);
1069
1070                         CDEBUG(D_READA, "stopping statahead thread, pid %d\n",
1071                                cfs_curproc_pid());
1072                         l_wait_event(thread->t_ctl_waitq,
1073                                      thread_is_stopped(thread),
1074                                      &lwi);
1075                 } else {
1076                         cfs_spin_unlock(&lli->lli_sa_lock);
1077                 }
1078
1079                 /*
1080                  * Put the ref which was held when first statahead_enter.
1081                  * It maybe not the last ref for some statahead requests
1082                  * maybe inflight.
1083                  */
1084                 ll_sai_put(lli->lli_sai);
1085         } else {
1086                 lli->lli_opendir_pid = 0;
1087                 cfs_spin_unlock(&lli->lli_sa_lock);
1088         }
1089 }
1090
1091 enum {
1092         /**
1093          * not first dirent, or is "."
1094          */
1095         LS_NONE_FIRST_DE = 0,
1096         /**
1097          * the first non-hidden dirent
1098          */
1099         LS_FIRST_DE,
1100         /**
1101          * the first hidden dirent, that is "."
1102          */
1103         LS_FIRST_DOT_DE
1104 };
1105
1106 static int is_first_dirent(struct inode *dir, struct dentry *dentry)
1107 {
1108         struct ll_inode_info *lli = ll_i2info(dir);
1109         struct ll_dir_chain chain;
1110         struct qstr        *target = &dentry->d_name;
1111         struct page        *page;
1112         __u64               pos = 0;
1113         int                 dot_de;
1114         int                 rc = LS_NONE_FIRST_DE;
1115         ENTRY;
1116
1117         lli->lli_sa_pos = 0;
1118         ll_dir_chain_init(&chain);
1119         page = ll_get_dir_page(NULL, dir, pos, &chain);
1120
1121         while (1) {
1122                 struct lu_dirpage *dp;
1123                 struct lu_dirent  *ent;
1124
1125                 if (IS_ERR(page)) {
1126                         struct ll_inode_info *lli = ll_i2info(dir);
1127
1128                         rc = PTR_ERR(page);
1129                         CERROR("error reading dir "DFID" at "LPU64": "
1130                                "[rc %d] [parent %u]\n",
1131                                PFID(ll_inode2fid(dir)), pos,
1132                                rc, lli->lli_opendir_pid);
1133                         break;
1134                 }
1135
1136                 dp = page_address(page);
1137                 for (ent = lu_dirent_start(dp); ent != NULL;
1138                      ent = lu_dirent_next(ent)) {
1139                         __u64 hash;
1140                         int namelen;
1141                         char *name;
1142
1143                         hash = le64_to_cpu(ent->lde_hash);
1144                         /* The ll_get_dir_page() can return any page containing
1145                          * the given hash which may be not the start hash. */
1146                         if (unlikely(hash < pos))
1147                                 continue;
1148
1149                         namelen = le16_to_cpu(ent->lde_namelen);
1150                         if (unlikely(namelen == 0))
1151                                 /*
1152                                  * skip dummy record.
1153                                  */
1154                                 continue;
1155
1156                         name = ent->lde_name;
1157                         if (name[0] == '.') {
1158                                 if (namelen == 1)
1159                                         /*
1160                                          * skip "."
1161                                          */
1162                                         continue;
1163                                 else if (name[1] == '.' && namelen == 2)
1164                                         /*
1165                                          * skip ".."
1166                                          */
1167                                         continue;
1168                                 else
1169                                         dot_de = 1;
1170                         } else {
1171                                 dot_de = 0;
1172                         }
1173
1174                         if (dot_de && target->name[0] != '.') {
1175                                 CDEBUG(D_READA, "%.*s skip hidden file %.*s\n",
1176                                        target->len, target->name,
1177                                        namelen, name);
1178                                 continue;
1179                         }
1180
1181                         if (target->len != namelen ||
1182                             memcmp(target->name, name, namelen) != 0)
1183                                 rc = LS_NONE_FIRST_DE;
1184                         else if (!dot_de)
1185                                 rc = LS_FIRST_DE;
1186                         else
1187                                 rc = LS_FIRST_DOT_DE;
1188
1189                         ll_release_page(page, 0);
1190                         GOTO(out, rc);
1191                 }
1192                 pos = le64_to_cpu(dp->ldp_hash_end);
1193                 if (pos == MDS_DIR_END_OFF) {
1194                         /*
1195                          * End of directory reached.
1196                          */
1197                         ll_release_page(page, 0);
1198                         break;
1199                 } else if (1) {
1200                         /*
1201                          * chain is exhausted
1202                          * Normal case: continue to the next page.
1203                          */
1204                         ll_release_page(page, le32_to_cpu(dp->ldp_flags) &
1205                                               LDF_COLLIDE);
1206                         lli->lli_sa_pos = pos;
1207                         page = ll_get_dir_page(NULL, dir, pos, &chain);
1208                 } else {
1209                         /*
1210                          * go into overflow page.
1211                          */
1212                         LASSERT(le32_to_cpu(dp->ldp_flags) & LDF_COLLIDE);
1213                         ll_release_page(page, 1);
1214                 }
1215         }
1216         EXIT;
1217
1218 out:
1219         ll_dir_chain_fini(&chain);
1220         return rc;
1221 }
1222
1223 static void
1224 ll_sai_unplug(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
1225 {
1226         struct ptlrpc_thread *thread = &sai->sai_thread;
1227         struct ll_sb_info    *sbi    = ll_i2sbi(sai->sai_inode);
1228         int                  hit;
1229         ENTRY;
1230
1231         if (entry != NULL && entry->se_stat == SA_ENTRY_SUCC)
1232                 hit = 1;
1233         else
1234                 hit = 0;
1235
1236         ll_sa_entry_fini(sai, entry);
1237         if (hit) {
1238                 sai->sai_hit++;
1239                 sai->sai_consecutive_miss = 0;
1240                 sai->sai_max = min(2 * sai->sai_max, sbi->ll_sa_max);
1241         } else {
1242                 struct ll_inode_info *lli = ll_i2info(sai->sai_inode);
1243
1244                 sai->sai_miss++;
1245                 sai->sai_consecutive_miss++;
1246                 if (sa_low_hit(sai) && thread_is_running(thread)) {
1247                         atomic_inc(&sbi->ll_sa_wrong);
1248                         CDEBUG(D_READA, "Statahead for dir "DFID" hit "
1249                                "ratio too low: hit/miss "LPU64"/"LPU64
1250                                ", sent/replied "LPU64"/"LPU64", stopping "
1251                                "statahead thread: pid %d\n",
1252                                PFID(&lli->lli_fid), sai->sai_hit,
1253                                sai->sai_miss, sai->sai_sent,
1254                                sai->sai_replied, cfs_curproc_pid());
1255                         cfs_spin_lock(&lli->lli_sa_lock);
1256                         if (!thread_is_stopped(thread))
1257                                 thread_set_flags(thread, SVC_STOPPING);
1258                         cfs_spin_unlock(&lli->lli_sa_lock);
1259                 }
1260         }
1261
1262         if (!thread_is_stopped(thread))
1263                 cfs_waitq_signal(&thread->t_ctl_waitq);
1264
1265         EXIT;
1266 }
1267
1268 /**
1269  * Start statahead thread if this is the first dir entry.
1270  * Otherwise if a thread is started already, wait it until it is ahead of me.
1271  * \retval 1       -- find entry with lock in cache, the caller needs to do
1272  *                    nothing.
1273  * \retval 0       -- find entry in cache, but without lock, the caller needs
1274  *                    refresh from MDS.
1275  * \retval others  -- the caller need to process as non-statahead.
1276  */
1277 int do_statahead_enter(struct inode *dir, struct dentry **dentryp,
1278                        int only_unplug)
1279 {
1280         struct ll_inode_info     *lli   = ll_i2info(dir);
1281         struct ll_statahead_info *sai   = lli->lli_sai;
1282         struct dentry            *parent;
1283         struct ll_sa_entry       *entry;
1284         struct ptlrpc_thread     *thread;
1285         struct l_wait_info        lwi   = { 0 };
1286         int                       rc    = 0;
1287         ENTRY;
1288
1289         LASSERT(lli->lli_opendir_pid == cfs_curproc_pid());
1290
1291         if (sai) {
1292                 thread = &sai->sai_thread;
1293                 if (unlikely(thread_is_stopped(thread) &&
1294                              cfs_list_empty(&sai->sai_entries_stated))) {
1295                         /* to release resource */
1296                         ll_stop_statahead(dir, lli->lli_opendir_key);
1297                         RETURN(-EAGAIN);
1298                 }
1299
1300                 if ((*dentryp)->d_name.name[0] == '.') {
1301                         if (sai->sai_ls_all ||
1302                             sai->sai_miss_hidden >= sai->sai_skip_hidden) {
1303                                 /*
1304                                  * Hidden dentry is the first one, or statahead
1305                                  * thread does not skip so many hidden dentries
1306                                  * before "sai_ls_all" enabled as below.
1307                                  */
1308                         } else {
1309                                 if (!sai->sai_ls_all)
1310                                         /*
1311                                          * It maybe because hidden dentry is not
1312                                          * the first one, "sai_ls_all" was not
1313                                          * set, then "ls -al" missed. Enable
1314                                          * "sai_ls_all" for such case.
1315                                          */
1316                                         sai->sai_ls_all = 1;
1317
1318                                 /*
1319                                  * Such "getattr" has been skipped before
1320                                  * "sai_ls_all" enabled as above.
1321                                  */
1322                                 sai->sai_miss_hidden++;
1323                                 RETURN(-EAGAIN);
1324                         }
1325                 }
1326
1327                 entry = ll_sa_entry_get_byname(sai, &(*dentryp)->d_name);
1328                 if (entry == NULL || only_unplug) {
1329                         ll_sai_unplug(sai, entry);
1330                         RETURN(entry ? 1 : -EAGAIN);
1331                 }
1332
1333                 while (!ll_sa_entry_stated(entry) &&
1334                        sai->sai_in_readpage &&
1335                        !sa_received_empty(sai))
1336                         do_statahead_interpret(sai, entry);
1337
1338                 if (!ll_sa_entry_stated(entry)) {
1339                         sai->sai_index_wait = entry->se_index;
1340                         lwi = LWI_TIMEOUT_INTR(cfs_time_seconds(30), NULL,
1341                                                LWI_ON_SIGNAL_NOOP, NULL);
1342                         rc = l_wait_event(sai->sai_waitq,
1343                                           ll_sa_entry_stated(entry) ||
1344                                           thread_is_stopped(thread),
1345                                           &lwi);
1346                         if (rc < 0) {
1347                                 ll_sai_unplug(sai, entry);
1348                                 RETURN(-EAGAIN);
1349                         }
1350                 }
1351
1352                 if (entry->se_stat == SA_ENTRY_SUCC &&
1353                     entry->se_inode != NULL) {
1354                         struct inode *inode = entry->se_inode;
1355                         struct lookup_intent it = { .it_op = IT_GETATTR,
1356                                                     .d.lustre.it_lock_handle =
1357                                                      entry->se_handle };
1358                         struct ll_dentry_data *lld;
1359                         __u64 bits;
1360
1361                         rc = md_revalidate_lock(ll_i2mdexp(dir), &it,
1362                                                 ll_inode2fid(inode), &bits);
1363                         if (rc == 1) {
1364                                 if ((*dentryp)->d_inode == NULL) {
1365                                         *dentryp = ll_find_alias(inode,
1366                                                                  *dentryp);
1367                                         lld = ll_d2d(*dentryp);
1368                                         if (unlikely(lld == NULL))
1369                                                 ll_dops_init(*dentryp, 1, 1);
1370                                 } else {
1371                                         LASSERT((*dentryp)->d_inode == inode);
1372
1373                                         ll_dentry_rehash(*dentryp, 0);
1374                                         iput(inode);
1375                                 }
1376                                 entry->se_inode = NULL;
1377
1378                                 ll_dentry_reset_flags(*dentryp, bits);
1379                                 ll_intent_release(&it);
1380                         }
1381                 }
1382
1383                 ll_sai_unplug(sai, entry);
1384                 RETURN(rc);
1385         }
1386
1387         /* I am the "lli_opendir_pid" owner, only me can set "lli_sai". */
1388         rc = is_first_dirent(dir, *dentryp);
1389         if (rc == LS_NONE_FIRST_DE)
1390                 /* It is not "ls -{a}l" operation, no need statahead for it. */
1391                 GOTO(out, rc = -EAGAIN);
1392
1393         sai = ll_sai_alloc();
1394         if (sai == NULL)
1395                 GOTO(out, rc = -ENOMEM);
1396
1397         sai->sai_ls_all = (rc == LS_FIRST_DOT_DE);
1398         sai->sai_inode = igrab(dir);
1399         if (unlikely(sai->sai_inode == NULL)) {
1400                 CWARN("Do not start stat ahead on dying inode "DFID"\n",
1401                       PFID(&lli->lli_fid));
1402                 GOTO(out, rc = -ESTALE);
1403         }
1404
1405         /* get parent reference count here, and put it in ll_statahead_thread */
1406         parent = dget((*dentryp)->d_parent);
1407         if (unlikely(sai->sai_inode != parent->d_inode)) {
1408                 struct ll_inode_info *nlli = ll_i2info(parent->d_inode);
1409
1410                 CWARN("Race condition, someone changed %.*s just now: "
1411                       "old parent "DFID", new parent "DFID"\n",
1412                       (*dentryp)->d_name.len, (*dentryp)->d_name.name,
1413                       PFID(&lli->lli_fid), PFID(&nlli->lli_fid));
1414                 dput(parent);
1415                 iput(sai->sai_inode);
1416                 GOTO(out, rc = -EAGAIN);
1417         }
1418
1419         lli->lli_sai = sai;
1420         rc = cfs_create_thread(ll_statahead_thread, parent, 0);
1421         thread = &sai->sai_thread;
1422         if (rc < 0) {
1423                 CERROR("can't start ll_sa thread, rc: %d\n", rc);
1424                 dput(parent);
1425                 lli->lli_opendir_key = NULL;
1426                 thread_set_flags(thread, SVC_STOPPED);
1427                 ll_sai_put(sai);
1428                 LASSERT(lli->lli_sai == NULL);
1429                 RETURN(-EAGAIN);
1430         }
1431
1432         l_wait_event(thread->t_ctl_waitq,
1433                      thread_is_running(thread) || thread_is_stopped(thread),
1434                      &lwi);
1435
1436         /*
1437          * We don't stat-ahead for the first dirent since we are already in
1438          * lookup, and -EEXIST also indicates that this is the first dirent.
1439          */
1440         RETURN(-EEXIST);
1441
1442 out:
1443         if (sai != NULL)
1444                 OBD_FREE_PTR(sai);
1445         cfs_spin_lock(&lli->lli_sa_lock);
1446         lli->lli_opendir_key = NULL;
1447         lli->lli_opendir_pid = 0;
1448         cfs_spin_unlock(&lli->lli_sa_lock);
1449         return rc;
1450 }