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 agl_should_run(struct ll_statahead_info *sai,
 144                                  struct inode *inode)
 145 {
 146         if (inode != NULL && S_ISREG(inode->i_mode) &&
 147             ll_i2info(inode)->lli_smd != NULL && sai->sai_agl_valid)
 148                 return 1;
 149         return 0;
 150 }
 151
 152 static inline struct ll_sa_entry *
 153 sa_first_received_entry(struct ll_statahead_info *sai)
 154 {
 155         return cfs_list_entry(sai->sai_entries_received.next,
 156                               struct ll_sa_entry, se_list);
 157 }
 158
 159 static inline struct ll_inode_info *
 160 agl_first_entry(struct ll_statahead_info *sai)
 161 {
 162         return cfs_list_entry(sai->sai_entries_agl.next,
 163                               struct ll_inode_info, lli_agl_list);
 164 }
 165
 166 static inline int sa_sent_full(struct ll_statahead_info *sai)
 167 {
 168         return cfs_atomic_read(&sai->sai_cache_count) >= sai->sai_max;
 169 }
 170
 171 static inline int sa_received_empty(struct ll_statahead_info *sai)
 172 {
 173         return cfs_list_empty(&sai->sai_entries_received);
 174 }
 175
 176 static inline int agl_list_empty(struct ll_statahead_info *sai)
 177 {
 178         return cfs_list_empty(&sai->sai_entries_agl);
 179 }
 180
 181 /**
 182  * (1) hit ratio less than 80%
 183  * or
 184  * (2) consecutive miss more than 8
 185  * then means low hit.
 186  */
 187 static inline int sa_low_hit(struct ll_statahead_info *sai)
 188 {
 189         return ((sai->sai_hit > 7 && sai->sai_hit < 4 * sai->sai_miss) ||
 190                 (sai->sai_consecutive_miss > 8));
 191 }
 192
 193 /*
 194  * If the given index is behind of statahead window more than
 195  * SA_OMITTED_ENTRY_MAX, then it is old.
 196  */
 197 static inline int is_omitted_entry(struct ll_statahead_info *sai, __u64 index)
 198 {
 199         return ((__u64)sai->sai_max + index + SA_OMITTED_ENTRY_MAX <
 200                  sai->sai_index);
 201 }
 202
 203 /*
 204  * Insert it into sai_entries_sent tail when init.
 205  */
 206 static struct ll_sa_entry *
 207 ll_sa_entry_alloc(struct ll_statahead_info *sai, __u64 index,
 208                   const char *name, int len)
 209 {
 210         struct ll_inode_info *lli;
 211         struct ll_sa_entry   *entry;
 212         int                   entry_size;
 213         char                 *dname;
 214         ENTRY;
 215
 216         entry_size = sizeof(struct ll_sa_entry) + (len & ~3) + 4;
 217         OBD_ALLOC(entry, entry_size);
 218         if (unlikely(entry == NULL))
 219                 RETURN(ERR_PTR(-ENOMEM));
 220
 221         CDEBUG(D_READA, "alloc sai entry %.*s(%p) index "LPU64"\n",
 222                len, name, entry, index);
 223
 224         entry->se_index = index;
 225
 226         /*
 227          * Statahead entry reference rules:
 228          *
 229          * 1) When statahead entry is initialized, its reference is set as 2.
 230          *    One reference is used by the directory scanner. When the scanner
 231          *    searches the statahead cache for the given name, it can perform
 232          *    lockless hash lookup (only the scanner can remove entry from hash
 233          *    list), and once found, it needn't to call "atomic_inc()" for the
 234          *    entry reference. So the performance is improved. After using the
 235          *    statahead entry, the scanner will call "atomic_dec()" to drop the
 236          *    reference held when initialization. If it is the last reference,
 237          *    the statahead entry will be freed.
 238          *
 239          * 2) All other threads, including statahead thread and ptlrpcd thread,
 240          *    when they process the statahead entry, the reference for target
 241          *    should be held to guarantee the entry will not be released by the
 242          *    directory scanner. After processing the entry, these threads will
 243          *    drop the entry reference. If it is the last reference, the entry
 244          *    will be freed.
 245          *
 246          *    The second reference when initializes the statahead entry is used
 247          *    by the statahead thread, following the rule 2).
 248          */
 249         cfs_atomic_set(&entry->se_refcount, 2);
 250         entry->se_stat = SA_ENTRY_INIT;
 251         entry->se_size = entry_size;
 252         dname = (char *)entry + sizeof(struct ll_sa_entry);
 253         memcpy(dname, name, len);
 254         dname[len] = 0;
 255         entry->se_qstr.hash = full_name_hash(name, len);
 256         entry->se_qstr.len = len;
 257         entry->se_qstr.name = dname;
 258
 259         lli = ll_i2info(sai->sai_inode);
 260         cfs_spin_lock(&lli->lli_sa_lock);
 261         cfs_list_add_tail(&entry->se_list, &sai->sai_entries_sent);
 262         cfs_spin_unlock(&lli->lli_sa_lock);
 263
 264         cfs_atomic_inc(&sai->sai_cache_count);
 265         ll_sa_entry_enhash(sai, entry);
 266
 267         RETURN(entry);
 268 }
 269
 270 /*
 271  * Used by the directory scanner to search entry with name.
 272  *
 273  * Only the caller can remove the entry from hash, so it is unnecessary to hold
 274  * hash lock. It is caller's duty to release the init refcount on the entry, so
 275  * it is also unnecessary to increase refcount on the entry.
 276  */
 277 static struct ll_sa_entry *
 278 ll_sa_entry_get_byname(struct ll_statahead_info *sai, const struct qstr *qstr)
 279 {
 280         struct ll_sa_entry *entry;
 281         int i = ll_sa_entry_hash(qstr->hash);
 282
 283         cfs_list_for_each_entry(entry, &sai->sai_cache[i], se_hash) {
 284                 if (entry->se_qstr.hash == qstr->hash &&
 285                     entry->se_qstr.len == qstr->len &&
 286                     memcmp(entry->se_qstr.name, qstr->name, qstr->len) == 0)
 287                         return entry;
 288         }
 289         return NULL;
 290 }
 291
 292 /*
 293  * Used by the async getattr request callback to find entry with index.
 294  *
 295  * Inside lli_sa_lock to prevent others to change the list during the search.
 296  * It needs to increase entry refcount before returning to guarantee that the
 297  * entry cannot be freed by others.
 298  */
 299 static struct ll_sa_entry *
 300 ll_sa_entry_get_byindex(struct ll_statahead_info *sai, __u64 index)
 301 {
 302         struct ll_sa_entry *entry;
 303
 304         cfs_list_for_each_entry(entry, &sai->sai_entries_sent, se_list) {
 305                 if (entry->se_index == index) {
 306                         cfs_atomic_inc(&entry->se_refcount);
 307                         return entry;
 308                 }
 309                 if (entry->se_index > index)
 310                         break;
 311         }
 312         return NULL;
 313 }
 314
 315 static void ll_sa_entry_cleanup(struct ll_statahead_info *sai,
 316                                  struct ll_sa_entry *entry)
 317 {
 318         struct md_enqueue_info *minfo = entry->se_minfo;
 319         struct ptlrpc_request  *req   = entry->se_req;
 320
 321         if (minfo) {
 322                 entry->se_minfo = NULL;
 323                 ll_intent_release(&minfo->mi_it);
 324                 iput(minfo->mi_dir);
 325                 OBD_FREE_PTR(minfo);
 326         }
 327
 328         if (req) {
 329                 entry->se_req = NULL;
 330                 ptlrpc_req_finished(req);
 331         }
 332 }
 333
 334 static void ll_sa_entry_put(struct ll_statahead_info *sai,
 335                              struct ll_sa_entry *entry)
 336 {
 337         if (cfs_atomic_dec_and_test(&entry->se_refcount)) {
 338                 CDEBUG(D_READA, "free sai entry %.*s(%p) index "LPU64"\n",
 339                        entry->se_qstr.len, entry->se_qstr.name, entry,
 340                        entry->se_index);
 341
 342                 LASSERT(ll_sa_entry_unhashed(entry));
 343                 LASSERT(ll_sa_entry_unlinked(entry));
 344
 345                 ll_sa_entry_cleanup(sai, entry);
 346                 if (entry->se_inode)
 347                         iput(entry->se_inode);
 348
 349                 OBD_FREE(entry, entry->se_size);
 350                 cfs_atomic_dec(&sai->sai_cache_count);
 351         }
 352 }
 353
 354 static inline void
 355 do_sai_entry_fini(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
 356 {
 357         struct ll_inode_info *lli = ll_i2info(sai->sai_inode);
 358
 359         ll_sa_entry_unhash(sai, entry);
 360
 361         cfs_spin_lock(&lli->lli_sa_lock);
 362         entry->se_stat = SA_ENTRY_DEST;
 363         if (likely(!ll_sa_entry_unlinked(entry)))
 364                 cfs_list_del_init(&entry->se_list);
 365         cfs_spin_unlock(&lli->lli_sa_lock);
 366
 367         ll_sa_entry_put(sai, entry);
 368 }
 369
 370 /*
 371  * Delete it from sai_entries_stated list when fini.
 372  */
 373 static void
 374 ll_sa_entry_fini(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
 375 {
 376         struct ll_sa_entry *pos, *next;
 377
 378         if (entry)
 379                 do_sai_entry_fini(sai, entry);
 380
 381         /* drop old entry from sent list */
 382         cfs_list_for_each_entry_safe(pos, next, &sai->sai_entries_sent,
 383                                      se_list) {
 384                 if (is_omitted_entry(sai, pos->se_index))
 385                         do_sai_entry_fini(sai, pos);
 386                 else
 387                         break;
 388         }
 389
 390         /* drop old entry from stated list */
 391         cfs_list_for_each_entry_safe(pos, next, &sai->sai_entries_stated,
 392                                      se_list) {
 393                 if (is_omitted_entry(sai, pos->se_index))
 394                         do_sai_entry_fini(sai, pos);
 395                 else
 396                         break;
 397         }
 398 }
 399
 400 /*
 401  * Inside lli_sa_lock.
 402  */
 403 static void
 404 do_sai_entry_to_stated(struct ll_statahead_info *sai,
 405                        struct ll_sa_entry *entry, int rc)
 406 {
 407         struct ll_sa_entry *se;
 408         cfs_list_t         *pos = &sai->sai_entries_stated;
 409
 410         if (!ll_sa_entry_unlinked(entry))
 411                 cfs_list_del_init(&entry->se_list);
 412
 413         cfs_list_for_each_entry_reverse(se, &sai->sai_entries_stated, se_list) {
 414                 if (se->se_index < entry->se_index) {
 415                         pos = &se->se_list;
 416                         break;
 417                 }
 418         }
 419
 420         cfs_list_add(&entry->se_list, pos);
 421         entry->se_stat = rc;
 422 }
 423
 424 /*
 425  * Move entry to sai_entries_stated and sort with the index.
 426  * \retval 1    -- entry to be destroyed.
 427  * \retval 0    -- entry is inserted into stated list.
 428  */
 429 static int
 430 ll_sa_entry_to_stated(struct ll_statahead_info *sai,
 431                        struct ll_sa_entry *entry, int rc)
 432 {
 433         struct ll_inode_info *lli = ll_i2info(sai->sai_inode);
 434         int                   ret = 1;
 435
 436         ll_sa_entry_cleanup(sai, entry);
 437
 438         cfs_spin_lock(&lli->lli_sa_lock);
 439         if (likely(entry->se_stat != SA_ENTRY_DEST)) {
 440                 do_sai_entry_to_stated(sai, entry, rc);
 441                 ret = 0;
 442         }
 443         cfs_spin_unlock(&lli->lli_sa_lock);
 444
 445         return ret;
 446 }
 447
 448 /*
 449  * Insert inode into the list of sai_entries_agl.
 450  */
 451 static void ll_agl_add(struct ll_statahead_info *sai,
 452                        struct inode *inode, int index)
 453 {
 454         struct ll_inode_info *child  = ll_i2info(inode);
 455         struct ll_inode_info *parent = ll_i2info(sai->sai_inode);
 456         int                   added  = 0;
 457
 458         cfs_spin_lock(&child->lli_agl_lock);
 459         if (child->lli_agl_index == 0) {
 460                 child->lli_agl_index = index;
 461                 cfs_spin_unlock(&child->lli_agl_lock);
 462
 463                 LASSERT(cfs_list_empty(&child->lli_agl_list));
 464
 465                 igrab(inode);
 466                 cfs_spin_lock(&parent->lli_agl_lock);
 467                 if (agl_list_empty(sai))
 468                         added = 1;
 469                 cfs_list_add_tail(&child->lli_agl_list, &sai->sai_entries_agl);
 470                 cfs_spin_unlock(&parent->lli_agl_lock);
 471         } else {
 472                 cfs_spin_unlock(&child->lli_agl_lock);
 473         }
 474
 475         if (added > 0)
 476                 cfs_waitq_signal(&sai->sai_agl_thread.t_ctl_waitq);
 477 }
 478
 479 static struct ll_statahead_info *ll_sai_alloc(void)
 480 {
 481         struct ll_statahead_info *sai;
 482         int                       i;
 483         ENTRY;
 484
 485         OBD_ALLOC_PTR(sai);
 486         if (!sai)
 487                 RETURN(NULL);
 488
 489         cfs_atomic_set(&sai->sai_refcount, 1);
 490
 491         cfs_spin_lock(&sai_generation_lock);
 492         sai->sai_generation = ++sai_generation;
 493         if (unlikely(sai_generation == 0))
 494                 sai->sai_generation = ++sai_generation;
 495         cfs_spin_unlock(&sai_generation_lock);
 496
 497         sai->sai_max = LL_SA_RPC_MIN;
 498         sai->sai_index = 1;
 499         cfs_waitq_init(&sai->sai_waitq);
 500         cfs_waitq_init(&sai->sai_thread.t_ctl_waitq);
 501         cfs_waitq_init(&sai->sai_agl_thread.t_ctl_waitq);
 502
 503         CFS_INIT_LIST_HEAD(&sai->sai_entries_sent);
 504         CFS_INIT_LIST_HEAD(&sai->sai_entries_received);
 505         CFS_INIT_LIST_HEAD(&sai->sai_entries_stated);
 506         CFS_INIT_LIST_HEAD(&sai->sai_entries_agl);
 507
 508         for (i = 0; i < LL_SA_CACHE_SIZE; i++) {
 509                 CFS_INIT_LIST_HEAD(&sai->sai_cache[i]);
 510                 cfs_spin_lock_init(&sai->sai_cache_lock[i]);
 511         }
 512         cfs_atomic_set(&sai->sai_cache_count, 0);
 513
 514         RETURN(sai);
 515 }
 516
 517 static inline struct ll_statahead_info *
 518 ll_sai_get(struct ll_statahead_info *sai)
 519 {
 520         cfs_atomic_inc(&sai->sai_refcount);
 521         return sai;
 522 }
 523
 524 static void ll_sai_put(struct ll_statahead_info *sai)
 525 {
 526         struct inode         *inode = sai->sai_inode;
 527         struct ll_inode_info *lli   = ll_i2info(inode);
 528         ENTRY;
 529
 530         if (cfs_atomic_dec_and_lock(&sai->sai_refcount, &lli->lli_sa_lock)) {
 531                 struct ll_sa_entry *entry, *next;
 532
 533                 if (unlikely(cfs_atomic_read(&sai->sai_refcount) > 0)) {
 534                         /* It is race case, the interpret callback just hold
 535                          * a reference count */
 536                         cfs_spin_unlock(&lli->lli_sa_lock);
 537                         RETURN_EXIT;
 538                 }
 539
 540                 LASSERT(lli->lli_opendir_key == NULL);
 541                 LASSERT(thread_is_stopped(&sai->sai_thread));
 542                 LASSERT(thread_is_stopped(&sai->sai_agl_thread));
 543
 544                 lli->lli_sai = NULL;
 545                 lli->lli_opendir_pid = 0;
 546                 cfs_spin_unlock(&lli->lli_sa_lock);
 547
 548                 if (sai->sai_sent > sai->sai_replied)
 549                         CDEBUG(D_READA,"statahead for dir "DFID" does not "
 550                               "finish: [sent:"LPU64"] [replied:"LPU64"]\n",
 551                               PFID(&lli->lli_fid),
 552                               sai->sai_sent, sai->sai_replied);
 553
 554                 cfs_list_for_each_entry_safe(entry, next,
 555                                              &sai->sai_entries_sent, se_list)
 556                         do_sai_entry_fini(sai, entry);
 557
 558                 LASSERT(sa_received_empty(sai));
 559
 560                 cfs_list_for_each_entry_safe(entry, next,
 561                                              &sai->sai_entries_stated, se_list)
 562                         do_sai_entry_fini(sai, entry);
 563
 564                 LASSERT(cfs_atomic_read(&sai->sai_cache_count) == 0);
 565                 LASSERT(agl_list_empty(sai));
 566
 567                 iput(inode);
 568                 OBD_FREE_PTR(sai);
 569         }
 570
 571         EXIT;
 572 }
 573
 574 /* Do NOT forget to drop inode refcount when into sai_entries_agl. */
 575 static void ll_agl_trigger(struct inode *inode, struct ll_statahead_info *sai)
 576 {
 577         struct ll_inode_info *lli   = ll_i2info(inode);
 578         __u64                 index = lli->lli_agl_index;
 579         int                   rc;
 580         ENTRY;
 581
 582         LASSERT(cfs_list_empty(&lli->lli_agl_list));
 583
 584         /* AGL maybe fall behind statahead with one entry */
 585         if (is_omitted_entry(sai, index + 1)) {
 586                 lli->lli_agl_index = 0;
 587                 iput(inode);
 588                 RETURN_EXIT;
 589         }
 590
 591         /* Someone is in glimpse (sync or async), do nothing. */
 592         rc = cfs_down_write_trylock(&lli->lli_glimpse_sem);
 593         if (rc == 0) {
 594                 lli->lli_agl_index = 0;
 595                 iput(inode);
 596                 RETURN_EXIT;
 597         }
 598
 599         /*
 600          * Someone triggered glimpse within 1 sec before.
 601          * 1) The former glimpse succeeded with glimpse lock granted by OST, and
 602          *    if the lock is still cached on client, AGL needs to do nothing. If
 603          *    it is cancelled by other client, AGL maybe cannot obtaion new lock
 604          *    for no glimpse callback triggered by AGL.
 605          * 2) The former glimpse succeeded, but OST did not grant glimpse lock.
 606          *    Under such case, it is quite possible that the OST will not grant
 607          *    glimpse lock for AGL also.
 608          * 3) The former glimpse failed, compared with other two cases, it is
 609          *    relative rare. AGL can ignore such case, and it will not muchly
 610          *    affect the performance.
 611          */
 612         if (lli->lli_glimpse_time != 0 &&
 613             cfs_time_before(cfs_time_shift(-1), lli->lli_glimpse_time)) {
 614                 cfs_up_write(&lli->lli_glimpse_sem);
 615                 lli->lli_agl_index = 0;
 616                 iput(inode);
 617                 RETURN_EXIT;
 618         }
 619
 620         CDEBUG(D_READA, "Handling (init) async glimpse: inode = "
 621                DFID", idx = "LPU64"\n", PFID(&lli->lli_fid), index);
 622
 623         cl_agl(inode);
 624         lli->lli_agl_index = 0;
 625         lli->lli_glimpse_time = cfs_time_current();
 626         cfs_up_write(&lli->lli_glimpse_sem);
 627
 628         CDEBUG(D_READA, "Handled (init) async glimpse: inode= "
 629                DFID", idx = "LPU64", rc = %d\n",
 630                PFID(&lli->lli_fid), index, rc);
 631
 632         iput(inode);
 633
 634         EXIT;
 635 }
 636
 637 static void do_statahead_interpret(struct ll_statahead_info *sai,
 638                                    struct ll_sa_entry *target)
 639 {
 640         struct inode           *dir   = sai->sai_inode;
 641         struct inode           *child;
 642         struct ll_inode_info   *lli   = ll_i2info(dir);
 643         struct ll_sa_entry     *entry;
 644         struct md_enqueue_info *minfo;
 645         struct lookup_intent   *it;
 646         struct ptlrpc_request  *req;
 647         struct mdt_body        *body;
 648         int                     rc    = 0;
 649         ENTRY;
 650
 651         cfs_spin_lock(&lli->lli_sa_lock);
 652         if (target != NULL && target->se_req != NULL &&
 653             !cfs_list_empty(&target->se_list)) {
 654                 entry = target;
 655         } else if (unlikely(sa_received_empty(sai))) {
 656                 cfs_spin_unlock(&lli->lli_sa_lock);
 657                 RETURN_EXIT;
 658         } else {
 659                 entry = sa_first_received_entry(sai);
 660         }
 661
 662         cfs_atomic_inc(&entry->se_refcount);
 663         cfs_list_del_init(&entry->se_list);
 664         cfs_spin_unlock(&lli->lli_sa_lock);
 665
 666         LASSERT(entry->se_handle != 0);
 667
 668         minfo = entry->se_minfo;
 669         it = &minfo->mi_it;
 670         req = entry->se_req;
 671         body = req_capsule_server_get(&req->rq_pill, &RMF_MDT_BODY);
 672         if (body == NULL)
 673                 GOTO(out, rc = -EFAULT);
 674
 675         child = entry->se_inode;
 676         if (child == NULL) {
 677                 /*
 678                  * lookup.
 679                  */
 680                 LASSERT(fid_is_zero(&minfo->mi_data.op_fid2));
 681
 682                 /* XXX: No fid in reply, this is probaly cross-ref case.
 683                  * SA can't handle it yet. */
 684                 if (body->valid & OBD_MD_MDS)
 685                         GOTO(out, rc = -EAGAIN);
 686         } else {
 687                 /*
 688                  * revalidate.
 689                  */
 690                 /* unlinked and re-created with the same name */
 691                 if (unlikely(!lu_fid_eq(&minfo->mi_data.op_fid2, &body->fid1))){
 692                         entry->se_inode = NULL;
 693                         iput(child);
 694                         child = NULL;
 695                 }
 696         }
 697
 698         it->d.lustre.it_lock_handle = entry->se_handle;
 699         rc = md_revalidate_lock(ll_i2mdexp(dir), it, NULL, NULL);
 700         if (rc != 1)
 701                 GOTO(out, rc = -EAGAIN);
 702
 703         rc = ll_prep_inode(&child, req, dir->i_sb);
 704         if (rc)
 705                 GOTO(out, rc);
 706
 707         CDEBUG(D_DLMTRACE, "setting l_data to inode %p (%lu/%u)\n",
 708                child, child->i_ino, child->i_generation);
 709         ll_set_lock_data(ll_i2sbi(dir)->ll_md_exp, child, it, NULL);
 710
 711         entry->se_inode = child;
 712
 713         if (agl_should_run(sai, child))
 714                 ll_agl_add(sai, child, entry->se_index);
 715
 716         EXIT;
 717
 718 out:
 719         /* The "ll_sa_entry_to_stated()" will drop related ldlm ibits lock
 720          * reference count by calling "ll_intent_drop_lock()" in spite of the
 721          * above operations failed or not. Do not worry about calling
 722          * "ll_intent_drop_lock()" more than once. */
 723         rc = ll_sa_entry_to_stated(sai, entry, rc < 0 ? rc : SA_ENTRY_SUCC);
 724         if (rc == 0 && entry->se_index == sai->sai_index_wait && target == NULL)
 725                 cfs_waitq_signal(&sai->sai_waitq);
 726         ll_sa_entry_put(sai, entry);
 727 }
 728
 729 static int ll_statahead_interpret(struct ptlrpc_request *req,
 730                                   struct md_enqueue_info *minfo, int rc)
 731 {
 732         struct lookup_intent     *it  = &minfo->mi_it;
 733         struct inode             *dir = minfo->mi_dir;
 734         struct ll_inode_info     *lli = ll_i2info(dir);
 735         struct ll_statahead_info *sai = NULL;
 736         struct ll_sa_entry       *entry;
 737         int                       wakeup;
 738         ENTRY;
 739
 740         if (it_disposition(it, DISP_LOOKUP_NEG))
 741                 rc = -ENOENT;
 742
 743         cfs_spin_lock(&lli->lli_sa_lock);
 744         /* stale entry */
 745         if (unlikely(lli->lli_sai == NULL ||
 746                      lli->lli_sai->sai_generation != minfo->mi_generation)) {
 747                 cfs_spin_unlock(&lli->lli_sa_lock);
 748                 GOTO(out, rc = -ESTALE);
 749         } else {
 750                 sai = ll_sai_get(lli->lli_sai);
 751                 if (unlikely(!thread_is_running(&sai->sai_thread))) {
 752                         sai->sai_replied++;
 753                         cfs_spin_unlock(&lli->lli_sa_lock);
 754                         GOTO(out, rc = -EBADFD);
 755                 }
 756
 757                 entry = ll_sa_entry_get_byindex(sai, minfo->mi_cbdata);
 758                 if (entry == NULL) {
 759                         sai->sai_replied++;
 760                         cfs_spin_unlock(&lli->lli_sa_lock);
 761                         GOTO(out, rc = -EIDRM);
 762                 }
 763
 764                 cfs_list_del_init(&entry->se_list);
 765                 if (rc != 0) {
 766                         sai->sai_replied++;
 767                         do_sai_entry_to_stated(sai, entry, rc);
 768                         cfs_spin_unlock(&lli->lli_sa_lock);
 769                         if (entry->se_index == sai->sai_index_wait)
 770                                 cfs_waitq_signal(&sai->sai_waitq);
 771                 } else {
 772                         entry->se_minfo = minfo;
 773                         entry->se_req = ptlrpc_request_addref(req);
 774                         /* Release the async ibits lock ASAP to avoid deadlock
 775                          * when statahead thread tries to enqueue lock on parent
 776                          * for readpage and other tries to enqueue lock on child
 777                          * with parent's lock held, for example: unlink. */
 778                         entry->se_handle = it->d.lustre.it_lock_handle;
 779                         ll_intent_drop_lock(it);
 780                         wakeup = sa_received_empty(sai);
 781                         cfs_list_add_tail(&entry->se_list,
 782                                           &sai->sai_entries_received);
 783                         sai->sai_replied++;
 784                         cfs_spin_unlock(&lli->lli_sa_lock);
 785                         if (wakeup)
 786                                 cfs_waitq_signal(&sai->sai_thread.t_ctl_waitq);
 787                 }
 788                 ll_sa_entry_put(sai, entry);
 789         }
 790
 791         EXIT;
 792
 793 out:
 794         if (rc != 0) {
 795                 ll_intent_release(it);
 796                 iput(dir);
 797                 OBD_FREE_PTR(minfo);
 798         }
 799         if (sai != NULL)
 800                 ll_sai_put(sai);
 801         return rc;
 802 }
 803
 804 static void sa_args_fini(struct md_enqueue_info *minfo,
 805                          struct ldlm_enqueue_info *einfo)
 806 {
 807         LASSERT(minfo && einfo);
 808         iput(minfo->mi_dir);
 809         capa_put(minfo->mi_data.op_capa1);
 810         capa_put(minfo->mi_data.op_capa2);
 811         OBD_FREE_PTR(minfo);
 812         OBD_FREE_PTR(einfo);
 813 }
 814
 815 /**
 816  * There is race condition between "capa_put" and "ll_statahead_interpret" for
 817  * accessing "op_data.op_capa[1,2]" as following:
 818  * "capa_put" releases "op_data.op_capa[1,2]"'s reference count after calling
 819  * "md_intent_getattr_async". But "ll_statahead_interpret" maybe run first, and
 820  * fill "op_data.op_capa[1,2]" as POISON, then cause "capa_put" access invalid
 821  * "ocapa". So here reserve "op_data.op_capa[1,2]" in "pcapa" before calling
 822  * "md_intent_getattr_async".
 823  */
 824 static int sa_args_init(struct inode *dir, struct inode *child,
 825                         struct ll_sa_entry *entry, struct md_enqueue_info **pmi,
 826                         struct ldlm_enqueue_info **pei,
 827                         struct obd_capa **pcapa)
 828 {
 829         struct qstr              *qstr = &entry->se_qstr;
 830         struct ll_inode_info     *lli  = ll_i2info(dir);
 831         struct md_enqueue_info   *minfo;
 832         struct ldlm_enqueue_info *einfo;
 833         struct md_op_data        *op_data;
 834
 835         OBD_ALLOC_PTR(einfo);
 836         if (einfo == NULL)
 837                 return -ENOMEM;
 838
 839         OBD_ALLOC_PTR(minfo);
 840         if (minfo == NULL) {
 841                 OBD_FREE_PTR(einfo);
 842                 return -ENOMEM;
 843         }
 844
 845         op_data = ll_prep_md_op_data(&minfo->mi_data, dir, child, qstr->name,
 846                                      qstr->len, 0, LUSTRE_OPC_ANY, NULL);
 847         if (IS_ERR(op_data)) {
 848                 OBD_FREE_PTR(einfo);
 849                 OBD_FREE_PTR(minfo);
 850                 return PTR_ERR(op_data);
 851         }
 852
 853         minfo->mi_it.it_op = IT_GETATTR;
 854         minfo->mi_dir = igrab(dir);
 855         minfo->mi_cb = ll_statahead_interpret;
 856         minfo->mi_generation = lli->lli_sai->sai_generation;
 857         minfo->mi_cbdata = entry->se_index;
 858
 859         einfo->ei_type   = LDLM_IBITS;
 860         einfo->ei_mode   = it_to_lock_mode(&minfo->mi_it);
 861         einfo->ei_cb_bl  = ll_md_blocking_ast;
 862         einfo->ei_cb_cp  = ldlm_completion_ast;
 863         einfo->ei_cb_gl  = NULL;
 864         einfo->ei_cbdata = NULL;
 865
 866         *pmi = minfo;
 867         *pei = einfo;
 868         pcapa[0] = op_data->op_capa1;
 869         pcapa[1] = op_data->op_capa2;
 870
 871         return 0;
 872 }
 873
 874 static int do_sa_lookup(struct inode *dir, struct ll_sa_entry *entry)
 875 {
 876         struct md_enqueue_info   *minfo;
 877         struct ldlm_enqueue_info *einfo;
 878         struct obd_capa          *capas[2];
 879         int                       rc;
 880         ENTRY;
 881
 882         rc = sa_args_init(dir, NULL, entry, &minfo, &einfo, capas);
 883         if (rc)
 884                 RETURN(rc);
 885
 886         rc = md_intent_getattr_async(ll_i2mdexp(dir), minfo, einfo);
 887         if (!rc) {
 888                 capa_put(capas[0]);
 889                 capa_put(capas[1]);
 890         } else {
 891                 sa_args_fini(minfo, einfo);
 892         }
 893
 894         RETURN(rc);
 895 }
 896
 897 /**
 898  * similar to ll_revalidate_it().
 899  * \retval      1 -- dentry valid
 900  * \retval      0 -- will send stat-ahead request
 901  * \retval others -- prepare stat-ahead request failed
 902  */
 903 static int do_sa_revalidate(struct inode *dir, struct ll_sa_entry *entry,
 904                             struct dentry *dentry)
 905 {
 906         struct inode             *inode = dentry->d_inode;
 907         struct lookup_intent      it = { .it_op = IT_GETATTR,
 908                                          .d.lustre.it_lock_handle = 0 };
 909         struct md_enqueue_info   *minfo;
 910         struct ldlm_enqueue_info *einfo;
 911         struct obd_capa          *capas[2];
 912         int rc;
 913         ENTRY;
 914
 915         if (unlikely(inode == NULL))
 916                 RETURN(1);
 917
 918         if (d_mountpoint(dentry))
 919                 RETURN(1);
 920
 921         if (unlikely(dentry == dentry->d_sb->s_root))
 922                 RETURN(1);
 923
 924         entry->se_inode = igrab(inode);
 925         rc = md_revalidate_lock(ll_i2mdexp(dir), &it, ll_inode2fid(inode),NULL);
 926         if (rc == 1) {
 927                 entry->se_handle = it.d.lustre.it_lock_handle;
 928                 ll_intent_release(&it);
 929                 RETURN(1);
 930         }
 931
 932         rc = sa_args_init(dir, inode, entry, &minfo, &einfo, capas);
 933         if (rc) {
 934                 entry->se_inode = NULL;
 935                 iput(inode);
 936                 RETURN(rc);
 937         }
 938
 939         rc = md_intent_getattr_async(ll_i2mdexp(dir), minfo, einfo);
 940         if (!rc) {
 941                 capa_put(capas[0]);
 942                 capa_put(capas[1]);
 943         } else {
 944                 entry->se_inode = NULL;
 945                 iput(inode);
 946                 sa_args_fini(minfo, einfo);
 947         }
 948
 949         RETURN(rc);
 950 }
 951
 952 static void ll_statahead_one(struct dentry *parent, const char* entry_name,
 953                              int entry_name_len)
 954 {
 955         struct inode             *dir    = parent->d_inode;
 956         struct ll_inode_info     *lli    = ll_i2info(dir);
 957         struct ll_statahead_info *sai    = lli->lli_sai;
 958         struct dentry            *dentry = NULL;
 959         struct ll_sa_entry       *entry;
 960         int                       rc;
 961         int                       rc1;
 962         ENTRY;
 963
 964         entry = ll_sa_entry_alloc(sai, sai->sai_index, entry_name,
 965                                   entry_name_len);
 966         if (IS_ERR(entry))
 967                 RETURN_EXIT;
 968
 969         dentry = d_lookup(parent, &entry->se_qstr);
 970         if (!dentry) {
 971                 rc = do_sa_lookup(dir, entry);
 972         } else {
 973                 rc = do_sa_revalidate(dir, entry, dentry);
 974                 if (rc == 1 && agl_should_run(sai, dentry->d_inode))
 975                         ll_agl_add(sai, dentry->d_inode, entry->se_index);
 976         }
 977
 978         if (dentry != NULL)
 979                 dput(dentry);
 980
 981         if (rc) {
 982                 rc1 = ll_sa_entry_to_stated(sai, entry,
 983                                         rc < 0 ? SA_ENTRY_INVA : SA_ENTRY_SUCC);
 984                 if (rc1 == 0 && entry->se_index == sai->sai_index_wait)
 985                         cfs_waitq_signal(&sai->sai_waitq);
 986         } else {
 987                 sai->sai_sent++;
 988         }
 989
 990         sai->sai_index++;
 991         /* drop one refcount on entry by ll_sa_entry_alloc */
 992         ll_sa_entry_put(sai, entry);
 993
 994         EXIT;
 995 }
 996
 997 static int ll_agl_thread(void *arg)
 998 {
 999         struct dentry            *parent = (struct dentry *)arg;
1000         struct inode             *dir    = parent->d_inode;
1001         struct ll_inode_info     *plli   = ll_i2info(dir);
1002         struct ll_inode_info     *clli;
1003         struct ll_sb_info        *sbi    = ll_i2sbi(dir);
1004         struct ll_statahead_info *sai    = ll_sai_get(plli->lli_sai);
1005         struct ptlrpc_thread     *thread = &sai->sai_agl_thread;
1006         struct l_wait_info        lwi    = { 0 };
1007         ENTRY;
1008
1009         {
1010                 char pname[16];
1011                 snprintf(pname, 15, "ll_agl_%u", plli->lli_opendir_pid);
1012                 cfs_daemonize(pname);
1013         }
1014
1015         CDEBUG(D_READA, "agl thread started: [pid %d] [parent %.*s]\n",
1016                cfs_curproc_pid(), parent->d_name.len, parent->d_name.name);
1017
1018         atomic_inc(&sbi->ll_agl_total);
1019         cfs_spin_lock(&plli->lli_agl_lock);
1020         sai->sai_agl_valid = 1;
1021         thread_set_flags(thread, SVC_RUNNING);
1022         cfs_spin_unlock(&plli->lli_agl_lock);
1023         cfs_waitq_signal(&thread->t_ctl_waitq);
1024
1025         while (1) {
1026                 l_wait_event(thread->t_ctl_waitq,
1027                              !agl_list_empty(sai) ||
1028                              !thread_is_running(thread),
1029                              &lwi);
1030
1031                 if (!thread_is_running(thread))
1032                         break;
1033
1034                 cfs_spin_lock(&plli->lli_agl_lock);
1035                 /* The statahead thread maybe help to process AGL entries,
1036                  * so check whether list empty again. */
1037                 if (!agl_list_empty(sai)) {
1038                         clli = agl_first_entry(sai);
1039                         cfs_list_del_init(&clli->lli_agl_list);
1040                         cfs_spin_unlock(&plli->lli_agl_lock);
1041                         ll_agl_trigger(&clli->lli_vfs_inode, sai);
1042                 } else {
1043                         cfs_spin_unlock(&plli->lli_agl_lock);
1044                 }
1045         }
1046
1047         cfs_spin_lock(&plli->lli_agl_lock);
1048         sai->sai_agl_valid = 0;
1049         while (!agl_list_empty(sai)) {
1050                 clli = agl_first_entry(sai);
1051                 cfs_list_del_init(&clli->lli_agl_list);
1052                 cfs_spin_unlock(&plli->lli_agl_lock);
1053                 clli->lli_agl_index = 0;
1054                 iput(&clli->lli_vfs_inode);
1055                 cfs_spin_lock(&plli->lli_agl_lock);
1056         }
1057         thread_set_flags(thread, SVC_STOPPED);
1058         cfs_spin_unlock(&plli->lli_agl_lock);
1059         cfs_waitq_signal(&thread->t_ctl_waitq);
1060         ll_sai_put(sai);
1061         CDEBUG(D_READA, "agl thread stopped: [pid %d] [parent %.*s]\n",
1062                cfs_curproc_pid(), parent->d_name.len, parent->d_name.name);
1063         RETURN(0);
1064 }
1065
1066 static void ll_start_agl(struct dentry *parent, struct ll_statahead_info *sai)
1067 {
1068         struct ptlrpc_thread *thread = &sai->sai_agl_thread;
1069         struct l_wait_info    lwi    = { 0 };
1070         int                   rc;
1071         ENTRY;
1072
1073         CDEBUG(D_READA, "start agl thread: [pid %d] [parent %.*s]\n",
1074                cfs_curproc_pid(), parent->d_name.len, parent->d_name.name);
1075
1076         rc = cfs_create_thread(ll_agl_thread, parent, 0);
1077         if (rc < 0) {
1078                 CERROR("can't start ll_agl thread, rc: %d\n", rc);
1079                 RETURN_EXIT;
1080         }
1081
1082         l_wait_event(thread->t_ctl_waitq,
1083                      thread_is_running(thread) || thread_is_stopped(thread),
1084                      &lwi);
1085         EXIT;
1086 }
1087
1088 static int ll_statahead_thread(void *arg)
1089 {
1090         struct dentry            *parent = (struct dentry *)arg;
1091         struct inode             *dir    = parent->d_inode;
1092         struct ll_inode_info     *plli   = ll_i2info(dir);
1093         struct ll_inode_info     *clli;
1094         struct ll_sb_info        *sbi    = ll_i2sbi(dir);
1095         struct ll_statahead_info *sai    = ll_sai_get(plli->lli_sai);
1096         struct ptlrpc_thread     *thread = &sai->sai_thread;
1097         struct page              *page;
1098         __u64                     pos    = 0;
1099         int                       first  = 0;
1100         int                       rc     = 0;
1101         struct ll_dir_chain       chain;
1102         struct l_wait_info        lwi    = { 0 };
1103         ENTRY;
1104
1105         {
1106                 char pname[16];
1107                 snprintf(pname, 15, "ll_sa_%u", plli->lli_opendir_pid);
1108                 cfs_daemonize(pname);
1109         }
1110
1111         CDEBUG(D_READA, "statahead thread started: [pid %d] [parent %.*s]\n",
1112                cfs_curproc_pid(), parent->d_name.len, parent->d_name.name);
1113
1114         if (sbi->ll_flags & LL_SBI_AGL_ENABLED)
1115                 ll_start_agl(parent, sai);
1116
1117         atomic_inc(&sbi->ll_sa_total);
1118         cfs_spin_lock(&plli->lli_sa_lock);
1119         thread_set_flags(thread, SVC_RUNNING);
1120         cfs_spin_unlock(&plli->lli_sa_lock);
1121         cfs_waitq_signal(&thread->t_ctl_waitq);
1122
1123         plli->lli_sa_pos = 0;
1124         ll_dir_chain_init(&chain);
1125         page = ll_get_dir_page(NULL, dir, pos, &chain);
1126
1127         while (1) {
1128                 struct lu_dirpage *dp;
1129                 struct lu_dirent  *ent;
1130
1131                 if (IS_ERR(page)) {
1132                         rc = PTR_ERR(page);
1133                         CDEBUG(D_READA, "error reading dir "DFID" at "LPU64
1134                                "/"LPU64": [rc %d] [parent %u]\n",
1135                                PFID(ll_inode2fid(dir)), pos, sai->sai_index,
1136                                rc, plli->lli_opendir_pid);
1137                         GOTO(out, rc);
1138                 }
1139
1140                 dp = page_address(page);
1141                 for (ent = lu_dirent_start(dp); ent != NULL;
1142                      ent = lu_dirent_next(ent)) {
1143                         __u64 hash;
1144                         int namelen;
1145                         char *name;
1146
1147                         hash = le64_to_cpu(ent->lde_hash);
1148                         if (unlikely(hash < pos))
1149                                 /*
1150                                  * Skip until we find target hash value.
1151                                  */
1152                                 continue;
1153
1154                         namelen = le16_to_cpu(ent->lde_namelen);
1155                         if (unlikely(namelen == 0))
1156                                 /*
1157                                  * Skip dummy record.
1158                                  */
1159                                 continue;
1160
1161                         name = ent->lde_name;
1162                         if (name[0] == '.') {
1163                                 if (namelen == 1) {
1164                                         /*
1165                                          * skip "."
1166                                          */
1167                                         continue;
1168                                 } else if (name[1] == '.' && namelen == 2) {
1169                                         /*
1170                                          * skip ".."
1171                                          */
1172                                         continue;
1173                                 } else if (!sai->sai_ls_all) {
1174                                         /*
1175                                          * skip hidden files.
1176                                          */
1177                                         sai->sai_skip_hidden++;
1178                                         continue;
1179                                 }
1180                         }
1181
1182                         /*
1183                          * don't stat-ahead first entry.
1184                          */
1185                         if (unlikely(++first == 1))
1186                                 continue;
1187
1188 keep_it:
1189                         l_wait_event(thread->t_ctl_waitq,
1190                                      !sa_sent_full(sai) ||
1191                                      !sa_received_empty(sai) ||
1192                                      !agl_list_empty(sai) ||
1193                                      !thread_is_running(thread),
1194                                      &lwi);
1195
1196 interpret_it:
1197                         while (!sa_received_empty(sai))
1198                                 do_statahead_interpret(sai, NULL);
1199
1200                         if (unlikely(!thread_is_running(thread))) {
1201                                 ll_release_page(page, 0);
1202                                 GOTO(out, rc = 0);
1203                         }
1204
1205                         /* If no window for metadata statahead, but there are
1206                          * some AGL entries to be triggered, then try to help
1207                          * to process the AGL entries. */
1208                         if (sa_sent_full(sai)) {
1209                                 cfs_spin_lock(&plli->lli_agl_lock);
1210                                 while (!agl_list_empty(sai)) {
1211                                         clli = agl_first_entry(sai);
1212                                         cfs_list_del_init(&clli->lli_agl_list);
1213                                         cfs_spin_unlock(&plli->lli_agl_lock);
1214                                         ll_agl_trigger(&clli->lli_vfs_inode,
1215                                                        sai);
1216
1217                                         if (!sa_received_empty(sai))
1218                                                 goto interpret_it;
1219
1220                                         if (unlikely(
1221                                                 !thread_is_running(thread))) {
1222                                                 ll_release_page(page, 0);
1223                                                 GOTO(out, rc = 0);
1224                                         }
1225
1226                                         if (!sa_sent_full(sai))
1227                                                 goto do_it;
1228
1229                                         cfs_spin_lock(&plli->lli_agl_lock);
1230                                 }
1231                                 cfs_spin_unlock(&plli->lli_agl_lock);
1232
1233                                 goto keep_it;
1234                         }
1235
1236 do_it:
1237                         ll_statahead_one(parent, name, namelen);
1238                 }
1239                 pos = le64_to_cpu(dp->ldp_hash_end);
1240                 if (pos == MDS_DIR_END_OFF) {
1241                         /*
1242                          * End of directory reached.
1243                          */
1244                         ll_release_page(page, 0);
1245                         while (1) {
1246                                 l_wait_event(thread->t_ctl_waitq,
1247                                              !sa_received_empty(sai) ||
1248                                              sai->sai_sent == sai->sai_replied||
1249                                              !thread_is_running(thread),
1250                                              &lwi);
1251
1252                                 while (!sa_received_empty(sai))
1253                                         do_statahead_interpret(sai, NULL);
1254
1255                                 if (unlikely(!thread_is_running(thread)))
1256                                         GOTO(out, rc = 0);
1257
1258                                 if (sai->sai_sent == sai->sai_replied &&
1259                                     sa_received_empty(sai))
1260                                         break;
1261                         }
1262
1263                         cfs_spin_lock(&plli->lli_agl_lock);
1264                         while (!agl_list_empty(sai) &&
1265                                thread_is_running(thread)) {
1266                                 clli = agl_first_entry(sai);
1267                                 cfs_list_del_init(&clli->lli_agl_list);
1268                                 cfs_spin_unlock(&plli->lli_agl_lock);
1269                                 ll_agl_trigger(&clli->lli_vfs_inode, sai);
1270                                 cfs_spin_lock(&plli->lli_agl_lock);
1271                         }
1272                         cfs_spin_unlock(&plli->lli_agl_lock);
1273
1274                         GOTO(out, rc = 0);
1275                 } else if (1) {
1276                         /*
1277                          * chain is exhausted.
1278                          * Normal case: continue to the next page.
1279                          */
1280                         ll_release_page(page, le32_to_cpu(dp->ldp_flags) &
1281                                               LDF_COLLIDE);
1282                         plli->lli_sa_pos = pos;
1283                         sai->sai_in_readpage = 1;
1284                         page = ll_get_dir_page(NULL, dir, pos, &chain);
1285                         sai->sai_in_readpage = 0;
1286                 } else {
1287                         LASSERT(le32_to_cpu(dp->ldp_flags) & LDF_COLLIDE);
1288                         ll_release_page(page, 1);
1289                         /*
1290                          * go into overflow page.
1291                          */
1292                 }
1293         }
1294         EXIT;
1295
1296 out:
1297         if (sai->sai_agl_valid) {
1298                 struct ptlrpc_thread *agl_thread = &sai->sai_agl_thread;
1299
1300                 cfs_spin_lock(&plli->lli_agl_lock);
1301                 thread_set_flags(agl_thread, SVC_STOPPING);
1302                 cfs_spin_unlock(&plli->lli_agl_lock);
1303                 cfs_waitq_signal(&agl_thread->t_ctl_waitq);
1304
1305                 CDEBUG(D_READA, "stop agl thread: [pid %d]\n",
1306                        cfs_curproc_pid());
1307                 l_wait_event(agl_thread->t_ctl_waitq,
1308                              thread_is_stopped(agl_thread),
1309                              &lwi);
1310         }
1311
1312         ll_dir_chain_fini(&chain);
1313         cfs_spin_lock(&plli->lli_sa_lock);
1314         if (!sa_received_empty(sai)) {
1315                 thread_set_flags(thread, SVC_STOPPING);
1316                 cfs_spin_unlock(&plli->lli_sa_lock);
1317
1318                 /* To release the resources held by received entries. */
1319                 while (!sa_received_empty(sai))
1320                         do_statahead_interpret(sai, NULL);
1321
1322                 cfs_spin_lock(&plli->lli_sa_lock);
1323         }
1324         thread_set_flags(thread, SVC_STOPPED);
1325         cfs_spin_unlock(&plli->lli_sa_lock);
1326         cfs_waitq_signal(&sai->sai_waitq);
1327         cfs_waitq_signal(&thread->t_ctl_waitq);
1328         ll_sai_put(sai);
1329         dput(parent);
1330         CDEBUG(D_READA, "statahead thread stopped: [pid %d] [parent %.*s]\n",
1331                cfs_curproc_pid(), parent->d_name.len, parent->d_name.name);
1332         return rc;
1333 }
1334
1335 /**
1336  * called in ll_file_release().
1337  */
1338 void ll_stop_statahead(struct inode *dir, void *key)
1339 {
1340         struct ll_inode_info *lli = ll_i2info(dir);
1341
1342         if (unlikely(key == NULL))
1343                 return;
1344
1345         cfs_spin_lock(&lli->lli_sa_lock);
1346         if (lli->lli_opendir_key != key || lli->lli_opendir_pid == 0) {
1347                 cfs_spin_unlock(&lli->lli_sa_lock);
1348                 return;
1349         }
1350
1351         lli->lli_opendir_key = NULL;
1352
1353         if (lli->lli_sai) {
1354                 struct l_wait_info lwi = { 0 };
1355                 struct ptlrpc_thread *thread = &lli->lli_sai->sai_thread;
1356
1357                 if (!thread_is_stopped(thread)) {
1358                         thread_set_flags(thread, SVC_STOPPING);
1359                         cfs_spin_unlock(&lli->lli_sa_lock);
1360                         cfs_waitq_signal(&thread->t_ctl_waitq);
1361
1362                         CDEBUG(D_READA, "stop statahead thread: [pid %d]\n",
1363                                cfs_curproc_pid());
1364                         l_wait_event(thread->t_ctl_waitq,
1365                                      thread_is_stopped(thread),
1366                                      &lwi);
1367                 } else {
1368                         cfs_spin_unlock(&lli->lli_sa_lock);
1369                 }
1370
1371                 /*
1372                  * Put the ref which was held when first statahead_enter.
1373                  * It maybe not the last ref for some statahead requests
1374                  * maybe inflight.
1375                  */
1376                 ll_sai_put(lli->lli_sai);
1377         } else {
1378                 lli->lli_opendir_pid = 0;
1379                 cfs_spin_unlock(&lli->lli_sa_lock);
1380         }
1381 }
1382
1383 enum {
1384         /**
1385          * not first dirent, or is "."
1386          */
1387         LS_NONE_FIRST_DE = 0,
1388         /**
1389          * the first non-hidden dirent
1390          */
1391         LS_FIRST_DE,
1392         /**
1393          * the first hidden dirent, that is "."
1394          */
1395         LS_FIRST_DOT_DE
1396 };
1397
1398 static int is_first_dirent(struct inode *dir, struct dentry *dentry)
1399 {
1400         struct ll_inode_info *lli    = ll_i2info(dir);
1401         struct ll_dir_chain   chain;
1402         struct qstr          *target = &dentry->d_name;
1403         struct page          *page;
1404         __u64                 pos    = 0;
1405         int                   dot_de;
1406         int                   rc     = LS_NONE_FIRST_DE;
1407         ENTRY;
1408
1409         lli->lli_sa_pos = 0;
1410         ll_dir_chain_init(&chain);
1411         page = ll_get_dir_page(NULL, dir, pos, &chain);
1412
1413         while (1) {
1414                 struct lu_dirpage *dp;
1415                 struct lu_dirent  *ent;
1416
1417                 if (IS_ERR(page)) {
1418                         struct ll_inode_info *lli = ll_i2info(dir);
1419
1420                         rc = PTR_ERR(page);
1421                         CERROR("error reading dir "DFID" at "LPU64": "
1422                                "[rc %d] [parent %u]\n",
1423                                PFID(ll_inode2fid(dir)), pos,
1424                                rc, lli->lli_opendir_pid);
1425                         break;
1426                 }
1427
1428                 dp = page_address(page);
1429                 for (ent = lu_dirent_start(dp); ent != NULL;
1430                      ent = lu_dirent_next(ent)) {
1431                         __u64 hash;
1432                         int namelen;
1433                         char *name;
1434
1435                         hash = le64_to_cpu(ent->lde_hash);
1436                         /* The ll_get_dir_page() can return any page containing
1437                          * the given hash which may be not the start hash. */
1438                         if (unlikely(hash < pos))
1439                                 continue;
1440
1441                         namelen = le16_to_cpu(ent->lde_namelen);
1442                         if (unlikely(namelen == 0))
1443                                 /*
1444                                  * skip dummy record.
1445                                  */
1446                                 continue;
1447
1448                         name = ent->lde_name;
1449                         if (name[0] == '.') {
1450                                 if (namelen == 1)
1451                                         /*
1452                                          * skip "."
1453                                          */
1454                                         continue;
1455                                 else if (name[1] == '.' && namelen == 2)
1456                                         /*
1457                                          * skip ".."
1458                                          */
1459                                         continue;
1460                                 else
1461                                         dot_de = 1;
1462                         } else {
1463                                 dot_de = 0;
1464                         }
1465
1466                         if (dot_de && target->name[0] != '.') {
1467                                 CDEBUG(D_READA, "%.*s skip hidden file %.*s\n",
1468                                        target->len, target->name,
1469                                        namelen, name);
1470                                 continue;
1471                         }
1472
1473                         if (target->len != namelen ||
1474                             memcmp(target->name, name, namelen) != 0)
1475                                 rc = LS_NONE_FIRST_DE;
1476                         else if (!dot_de)
1477                                 rc = LS_FIRST_DE;
1478                         else
1479                                 rc = LS_FIRST_DOT_DE;
1480
1481                         ll_release_page(page, 0);
1482                         GOTO(out, rc);
1483                 }
1484                 pos = le64_to_cpu(dp->ldp_hash_end);
1485                 if (pos == MDS_DIR_END_OFF) {
1486                         /*
1487                          * End of directory reached.
1488                          */
1489                         ll_release_page(page, 0);
1490                         break;
1491                 } else if (1) {
1492                         /*
1493                          * chain is exhausted
1494                          * Normal case: continue to the next page.
1495                          */
1496                         ll_release_page(page, le32_to_cpu(dp->ldp_flags) &
1497                                               LDF_COLLIDE);
1498                         lli->lli_sa_pos = pos;
1499                         page = ll_get_dir_page(NULL, dir, pos, &chain);
1500                 } else {
1501                         /*
1502                          * go into overflow page.
1503                          */
1504                         LASSERT(le32_to_cpu(dp->ldp_flags) & LDF_COLLIDE);
1505                         ll_release_page(page, 1);
1506                 }
1507         }
1508         EXIT;
1509
1510 out:
1511         ll_dir_chain_fini(&chain);
1512         return rc;
1513 }
1514
1515 static void
1516 ll_sai_unplug(struct ll_statahead_info *sai, struct ll_sa_entry *entry)
1517 {
1518         struct ptlrpc_thread *thread = &sai->sai_thread;
1519         struct ll_sb_info    *sbi    = ll_i2sbi(sai->sai_inode);
1520         int                   hit;
1521         ENTRY;
1522
1523         if (entry != NULL && entry->se_stat == SA_ENTRY_SUCC)
1524                 hit = 1;
1525         else
1526                 hit = 0;
1527
1528         ll_sa_entry_fini(sai, entry);
1529         if (hit) {
1530                 sai->sai_hit++;
1531                 sai->sai_consecutive_miss = 0;
1532                 sai->sai_max = min(2 * sai->sai_max, sbi->ll_sa_max);
1533         } else {
1534                 struct ll_inode_info *lli = ll_i2info(sai->sai_inode);
1535
1536                 sai->sai_miss++;
1537                 sai->sai_consecutive_miss++;
1538                 if (sa_low_hit(sai) && thread_is_running(thread)) {
1539                         atomic_inc(&sbi->ll_sa_wrong);
1540                         CDEBUG(D_READA, "Statahead for dir "DFID" hit "
1541                                "ratio too low: hit/miss "LPU64"/"LPU64
1542                                ", sent/replied "LPU64"/"LPU64", stopping "
1543                                "statahead thread: pid %d\n",
1544                                PFID(&lli->lli_fid), sai->sai_hit,
1545                                sai->sai_miss, sai->sai_sent,
1546                                sai->sai_replied, cfs_curproc_pid());
1547                         cfs_spin_lock(&lli->lli_sa_lock);
1548                         if (!thread_is_stopped(thread))
1549                                 thread_set_flags(thread, SVC_STOPPING);
1550                         cfs_spin_unlock(&lli->lli_sa_lock);
1551                 }
1552         }
1553
1554         if (!thread_is_stopped(thread))
1555                 cfs_waitq_signal(&thread->t_ctl_waitq);
1556
1557         EXIT;
1558 }
1559
1560 /**
1561  * Start statahead thread if this is the first dir entry.
1562  * Otherwise if a thread is started already, wait it until it is ahead of me.
1563  * \retval 1       -- find entry with lock in cache, the caller needs to do
1564  *                    nothing.
1565  * \retval 0       -- find entry in cache, but without lock, the caller needs
1566  *                    refresh from MDS.
1567  * \retval others  -- the caller need to process as non-statahead.
1568  */
1569 int do_statahead_enter(struct inode *dir, struct dentry **dentryp,
1570                        int only_unplug)
1571 {
1572         struct ll_inode_info     *lli   = ll_i2info(dir);
1573         struct ll_statahead_info *sai   = lli->lli_sai;
1574         struct dentry            *parent;
1575         struct ll_sa_entry       *entry;
1576         struct ptlrpc_thread     *thread;
1577         struct l_wait_info        lwi   = { 0 };
1578         int                       rc    = 0;
1579         ENTRY;
1580
1581         LASSERT(lli->lli_opendir_pid == cfs_curproc_pid());
1582
1583         if (sai) {
1584                 thread = &sai->sai_thread;
1585                 if (unlikely(thread_is_stopped(thread) &&
1586                              cfs_list_empty(&sai->sai_entries_stated))) {
1587                         /* to release resource */
1588                         ll_stop_statahead(dir, lli->lli_opendir_key);
1589                         RETURN(-EAGAIN);
1590                 }
1591
1592                 if ((*dentryp)->d_name.name[0] == '.') {
1593                         if (sai->sai_ls_all ||
1594                             sai->sai_miss_hidden >= sai->sai_skip_hidden) {
1595                                 /*
1596                                  * Hidden dentry is the first one, or statahead
1597                                  * thread does not skip so many hidden dentries
1598                                  * before "sai_ls_all" enabled as below.
1599                                  */
1600                         } else {
1601                                 if (!sai->sai_ls_all)
1602                                         /*
1603                                          * It maybe because hidden dentry is not
1604                                          * the first one, "sai_ls_all" was not
1605                                          * set, then "ls -al" missed. Enable
1606                                          * "sai_ls_all" for such case.
1607                                          */
1608                                         sai->sai_ls_all = 1;
1609
1610                                 /*
1611                                  * Such "getattr" has been skipped before
1612                                  * "sai_ls_all" enabled as above.
1613                                  */
1614                                 sai->sai_miss_hidden++;
1615                                 RETURN(-EAGAIN);
1616                         }
1617                 }
1618
1619                 entry = ll_sa_entry_get_byname(sai, &(*dentryp)->d_name);
1620                 if (entry == NULL || only_unplug) {
1621                         ll_sai_unplug(sai, entry);
1622                         RETURN(entry ? 1 : -EAGAIN);
1623                 }
1624
1625                 while (!ll_sa_entry_stated(entry) &&
1626                        sai->sai_in_readpage &&
1627                        !sa_received_empty(sai))
1628                         do_statahead_interpret(sai, entry);
1629
1630                 if (!ll_sa_entry_stated(entry)) {
1631                         sai->sai_index_wait = entry->se_index;
1632                         lwi = LWI_TIMEOUT_INTR(cfs_time_seconds(30), NULL,
1633                                                LWI_ON_SIGNAL_NOOP, NULL);
1634                         rc = l_wait_event(sai->sai_waitq,
1635                                           ll_sa_entry_stated(entry) ||
1636                                           thread_is_stopped(thread),
1637                                           &lwi);
1638                         if (rc < 0) {
1639                                 ll_sai_unplug(sai, entry);
1640                                 RETURN(-EAGAIN);
1641                         }
1642                 }
1643
1644                 if (entry->se_stat == SA_ENTRY_SUCC &&
1645                     entry->se_inode != NULL) {
1646                         struct inode *inode = entry->se_inode;
1647                         struct lookup_intent it = { .it_op = IT_GETATTR,
1648                                                     .d.lustre.it_lock_handle =
1649                                                      entry->se_handle };
1650                         struct ll_dentry_data *lld;
1651                         __u64 bits;
1652
1653                         rc = md_revalidate_lock(ll_i2mdexp(dir), &it,
1654                                                 ll_inode2fid(inode), &bits);
1655                         if (rc == 1) {
1656                                 if ((*dentryp)->d_inode == NULL) {
1657                                         *dentryp = ll_find_alias(inode,
1658                                                                  *dentryp);
1659                                         lld = ll_d2d(*dentryp);
1660                                         if (unlikely(lld == NULL))
1661                                                 ll_dops_init(*dentryp, 1, 1);
1662                                 } else {
1663                                         LASSERT((*dentryp)->d_inode == inode);
1664
1665                                         ll_dentry_rehash(*dentryp, 0);
1666                                         iput(inode);
1667                                 }
1668                                 entry->se_inode = NULL;
1669
1670                                 ll_dentry_reset_flags(*dentryp, bits);
1671                                 ll_intent_release(&it);
1672                         }
1673                 }
1674
1675                 ll_sai_unplug(sai, entry);
1676                 RETURN(rc);
1677         }
1678
1679         /* I am the "lli_opendir_pid" owner, only me can set "lli_sai". */
1680         rc = is_first_dirent(dir, *dentryp);
1681         if (rc == LS_NONE_FIRST_DE)
1682                 /* It is not "ls -{a}l" operation, no need statahead for it. */
1683                 GOTO(out, rc = -EAGAIN);
1684
1685         sai = ll_sai_alloc();
1686         if (sai == NULL)
1687                 GOTO(out, rc = -ENOMEM);
1688
1689         sai->sai_ls_all = (rc == LS_FIRST_DOT_DE);
1690         sai->sai_inode = igrab(dir);
1691         if (unlikely(sai->sai_inode == NULL)) {
1692                 CWARN("Do not start stat ahead on dying inode "DFID"\n",
1693                       PFID(&lli->lli_fid));
1694                 GOTO(out, rc = -ESTALE);
1695         }
1696
1697         /* get parent reference count here, and put it in ll_statahead_thread */
1698         parent = dget((*dentryp)->d_parent);
1699         if (unlikely(sai->sai_inode != parent->d_inode)) {
1700                 struct ll_inode_info *nlli = ll_i2info(parent->d_inode);
1701
1702                 CWARN("Race condition, someone changed %.*s just now: "
1703                       "old parent "DFID", new parent "DFID"\n",
1704                       (*dentryp)->d_name.len, (*dentryp)->d_name.name,
1705                       PFID(&lli->lli_fid), PFID(&nlli->lli_fid));
1706                 dput(parent);
1707                 iput(sai->sai_inode);
1708                 GOTO(out, rc = -EAGAIN);
1709         }
1710
1711         CDEBUG(D_READA, "start statahead thread: [pid %d] [parent %.*s]\n",
1712                cfs_curproc_pid(), parent->d_name.len, parent->d_name.name);
1713
1714         lli->lli_sai = sai;
1715         rc = cfs_create_thread(ll_statahead_thread, parent, 0);
1716         thread = &sai->sai_thread;
1717         if (rc < 0) {
1718                 CERROR("can't start ll_sa thread, rc: %d\n", rc);
1719                 dput(parent);
1720                 lli->lli_opendir_key = NULL;
1721                 thread_set_flags(thread, SVC_STOPPED);
1722                 ll_sai_put(sai);
1723                 LASSERT(lli->lli_sai == NULL);
1724                 RETURN(-EAGAIN);
1725         }
1726
1727         l_wait_event(thread->t_ctl_waitq,
1728                      thread_is_running(thread) || thread_is_stopped(thread),
1729                      &lwi);
1730
1731         /*
1732          * We don't stat-ahead for the first dirent since we are already in
1733          * lookup, and -EEXIST also indicates that this is the first dirent.
1734          */
1735         RETURN(-EEXIST);
1736
1737 out:
1738         if (sai != NULL)
1739                 OBD_FREE_PTR(sai);
1740         cfs_spin_lock(&lli->lli_sa_lock);
1741         lli->lli_opendir_key = NULL;
1742         lli->lli_opendir_pid = 0;
1743         cfs_spin_unlock(&lli->lli_sa_lock);
1744         return rc;
1745 }