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  2008 Sun Microsystems, Inc. All rights reserved
  30  * Use is subject to license terms.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  */
  36
  37 #include <linux/fs.h>
  38 #include <linux/sched.h>
  39 #include <linux/mm.h>
  40 #include <linux/smp_lock.h>
  41 #include <linux/highmem.h>
  42 #include <linux/pagemap.h>
  43
  44 #define DEBUG_SUBSYSTEM S_LLITE
  45
  46 #include <obd_support.h>
  47 #include <lustre_lite.h>
  48 #include <lustre_dlm.h>
  49 #include <linux/lustre_version.h>
  50 #include "llite_internal.h"
  51
  52 struct ll_sai_entry {
  53         struct list_head        se_list;
  54         unsigned int            se_index;
  55         int                     se_stat;
  56         struct ptlrpc_request  *se_req;
  57         struct md_enqueue_info *se_minfo;
  58 };
  59
  60 enum {
  61         SA_ENTRY_UNSTATED = 0,
  62         SA_ENTRY_STATED
  63 };
  64
  65 static unsigned int sai_generation = 0;
  66 static spinlock_t sai_generation_lock = SPIN_LOCK_UNLOCKED;
  67
  68 /**
  69  * Check whether first entry was stated already or not.
  70  * No need to hold lli_lock, for:
  71  * (1) it is me that remove entry from the list
  72  * (2) the statahead thread only add new entry to the list
  73  */
  74 static int ll_sai_entry_stated(struct ll_statahead_info *sai)
  75 {
  76         struct ll_sai_entry  *entry;
  77         int                   rc = 0;
  78
  79         if (!list_empty(&sai->sai_entries_stated)) {
  80                 entry = list_entry(sai->sai_entries_stated.next,
  81                                    struct ll_sai_entry, se_list);
  82                 if (entry->se_index == sai->sai_index_next)
  83                         rc = 1;
  84         }
  85         return rc;
  86 }
  87
  88 static inline int sa_received_empty(struct ll_statahead_info *sai)
  89 {
  90         return list_empty(&sai->sai_entries_received);
  91 }
  92
  93 static inline int sa_not_full(struct ll_statahead_info *sai)
  94 {
  95         return (sai->sai_index < sai->sai_hit + sai->sai_miss + sai->sai_max);
  96 }
  97
  98 static inline int sa_is_running(struct ll_statahead_info *sai)
  99 {
 100         return !!(sai->sai_thread.t_flags & SVC_RUNNING);
 101 }
 102
 103 static inline int sa_is_stopping(struct ll_statahead_info *sai)
 104 {
 105         return !!(sai->sai_thread.t_flags & SVC_STOPPING);
 106 }
 107
 108 static inline int sa_is_stopped(struct ll_statahead_info *sai)
 109 {
 110         return !!(sai->sai_thread.t_flags & SVC_STOPPED);
 111 }
 112
 113 /**
 114  * (1) hit ratio less than 80%
 115  * or
 116  * (2) consecutive miss more than 8
 117  */
 118 static inline int sa_low_hit(struct ll_statahead_info *sai)
 119 {
 120         return ((sai->sai_hit > 7 && sai->sai_hit < 4 * sai->sai_miss) ||
 121                 (sai->sai_consecutive_miss > 8));
 122 }
 123
 124 /**
 125  * process the deleted entry's member and free the entry.
 126  * (1) release intent
 127  * (2) free md_enqueue_info
 128  * (3) drop dentry's ref count
 129  * (4) release request's ref count
 130  */
 131 static void ll_sai_entry_cleanup(struct ll_sai_entry *entry, int free)
 132 {
 133         struct md_enqueue_info *minfo = entry->se_minfo;
 134         struct ptlrpc_request  *req = entry->se_req;
 135         ENTRY;
 136
 137         if (minfo) {
 138                 entry->se_minfo = NULL;
 139                 ll_intent_release(&minfo->mi_it);
 140                 dput(minfo->mi_dentry);
 141                 iput(minfo->mi_dir);
 142                 OBD_FREE_PTR(minfo);
 143         }
 144         if (req) {
 145                 entry->se_req = NULL;
 146                 ptlrpc_req_finished(req);
 147         }
 148         if (free) {
 149                 LASSERT(list_empty(&entry->se_list));
 150                 OBD_FREE_PTR(entry);
 151         }
 152
 153         EXIT;
 154 }
 155
 156 static struct ll_statahead_info *ll_sai_alloc(void)
 157 {
 158         struct ll_statahead_info *sai;
 159
 160         OBD_ALLOC_PTR(sai);
 161         if (!sai)
 162                 return NULL;
 163
 164         spin_lock(&sai_generation_lock);
 165         sai->sai_generation = ++sai_generation;
 166         if (unlikely(sai_generation == 0))
 167                 sai->sai_generation = ++sai_generation;
 168         spin_unlock(&sai_generation_lock);
 169         atomic_set(&sai->sai_refcount, 1);
 170         sai->sai_max = LL_SA_RPC_MIN;
 171         cfs_waitq_init(&sai->sai_waitq);
 172         cfs_waitq_init(&sai->sai_thread.t_ctl_waitq);
 173         CFS_INIT_LIST_HEAD(&sai->sai_entries_sent);
 174         CFS_INIT_LIST_HEAD(&sai->sai_entries_received);
 175         CFS_INIT_LIST_HEAD(&sai->sai_entries_stated);
 176         return sai;
 177 }
 178
 179 static inline
 180 struct ll_statahead_info *ll_sai_get(struct ll_statahead_info *sai)
 181 {
 182         LASSERT(sai);
 183         atomic_inc(&sai->sai_refcount);
 184         return sai;
 185 }
 186
 187 static void ll_sai_put(struct ll_statahead_info *sai)
 188 {
 189         struct inode         *inode = sai->sai_inode;
 190         struct ll_inode_info *lli;
 191         ENTRY;
 192
 193         LASSERT(inode != NULL);
 194         lli = ll_i2info(inode);
 195         LASSERT(lli->lli_sai == sai);
 196
 197         if (atomic_dec_and_test(&sai->sai_refcount)) {
 198                 struct ll_sai_entry *entry, *next;
 199
 200                 spin_lock(&lli->lli_lock);
 201                 if (unlikely(atomic_read(&sai->sai_refcount) > 0)) {
 202                         /* It is race case, the interpret callback just hold
 203                          * a reference count */
 204                         spin_unlock(&lli->lli_lock);
 205                         EXIT;
 206                         return;
 207                 }
 208
 209                 LASSERT(lli->lli_opendir_key == NULL);
 210                 lli->lli_sai = NULL;
 211                 lli->lli_opendir_pid = 0;
 212                 spin_unlock(&lli->lli_lock);
 213
 214                 LASSERT(sa_is_stopped(sai));
 215
 216                 if (sai->sai_sent > sai->sai_replied)
 217                         CDEBUG(D_READA,"statahead for dir "DFID" does not "
 218                               "finish: [sent:%u] [replied:%u]\n",
 219                               PFID(&lli->lli_fid),
 220                               sai->sai_sent, sai->sai_replied);
 221
 222                 list_for_each_entry_safe(entry, next, &sai->sai_entries_sent,
 223                                          se_list) {
 224                         list_del_init(&entry->se_list);
 225                         ll_sai_entry_cleanup(entry, 1);
 226                 }
 227                 list_for_each_entry_safe(entry, next, &sai->sai_entries_received,
 228                                          se_list) {
 229                         list_del_init(&entry->se_list);
 230                         ll_sai_entry_cleanup(entry, 1);
 231                 }
 232                 list_for_each_entry_safe(entry, next, &sai->sai_entries_stated,
 233                                          se_list) {
 234                         list_del_init(&entry->se_list);
 235                         ll_sai_entry_cleanup(entry, 1);
 236                 }
 237                 iput(inode);
 238                 OBD_FREE_PTR(sai);
 239         }
 240         EXIT;
 241 }
 242
 243 /**
 244  * insert it into sai_entries_sent tail when init.
 245  */
 246 static struct ll_sai_entry *
 247 ll_sai_entry_init(struct ll_statahead_info *sai, unsigned int index)
 248 {
 249         struct ll_inode_info *lli = ll_i2info(sai->sai_inode);
 250         struct ll_sai_entry  *entry;
 251         ENTRY;
 252
 253         OBD_ALLOC_PTR(entry);
 254         if (entry == NULL)
 255                 RETURN(ERR_PTR(-ENOMEM));
 256
 257         CDEBUG(D_READA, "alloc sai entry %p index %u\n",
 258                entry, index);
 259         entry->se_index = index;
 260         entry->se_stat  = SA_ENTRY_UNSTATED;
 261
 262         spin_lock(&lli->lli_lock);
 263         list_add_tail(&entry->se_list, &sai->sai_entries_sent);
 264         spin_unlock(&lli->lli_lock);
 265
 266         RETURN(entry);
 267 }
 268
 269 /**
 270  * delete it from sai_entries_stated head when fini, it need not
 271  * to process entry's member.
 272  */
 273 static void ll_sai_entry_fini(struct ll_statahead_info *sai)
 274 {
 275         struct ll_inode_info *lli = ll_i2info(sai->sai_inode);
 276         struct ll_sai_entry  *entry;
 277         ENTRY;
 278
 279         spin_lock(&lli->lli_lock);
 280         sai->sai_index_next++;
 281         if (likely(!list_empty(&sai->sai_entries_stated))) {
 282                 entry = list_entry(sai->sai_entries_stated.next,
 283                                    struct ll_sai_entry, se_list);
 284                 if (entry->se_index < sai->sai_index_next) {
 285                         list_del(&entry->se_list);
 286                         OBD_FREE_PTR(entry);
 287                 }
 288         } else
 289                 LASSERT(sa_is_stopped(sai));
 290         spin_unlock(&lli->lli_lock);
 291
 292         EXIT;
 293 }
 294
 295 /**
 296  * inside lli_lock.
 297  * \retval NULL : can not find the entry in sai_entries_sent with the index
 298  * \retval entry: find the entry in sai_entries_sent with the index
 299  */
 300 static struct ll_sai_entry *
 301 ll_sai_entry_set(struct ll_statahead_info *sai, unsigned int index, int stat,
 302                  struct ptlrpc_request *req, struct md_enqueue_info *minfo)
 303 {
 304         struct ll_sai_entry *entry;
 305         ENTRY;
 306
 307         if (!list_empty(&sai->sai_entries_sent)) {
 308                 list_for_each_entry(entry, &sai->sai_entries_sent, se_list) {
 309                         if (entry->se_index == index) {
 310                                 entry->se_stat = stat;
 311                                 entry->se_req = ptlrpc_request_addref(req);
 312                                 entry->se_minfo = minfo;
 313                                 RETURN(entry);
 314                         } else if (entry->se_index > index)
 315                                 RETURN(NULL);
 316                 }
 317         }
 318         RETURN(NULL);
 319 }
 320
 321 /**
 322  * inside lli_lock.
 323  * Move entry to sai_entries_received and
 324  * insert it into sai_entries_received tail.
 325  */
 326 static inline void
 327 ll_sai_entry_to_received(struct ll_statahead_info *sai, struct ll_sai_entry *entry)
 328 {
 329         if (!list_empty(&entry->se_list))
 330                 list_del_init(&entry->se_list);
 331         list_add_tail(&entry->se_list, &sai->sai_entries_received);
 332 }
 333
 334 /**
 335  * Move entry to sai_entries_stated and
 336  * sort with the index.
 337  */
 338 static int
 339 ll_sai_entry_to_stated(struct ll_statahead_info *sai, struct ll_sai_entry *entry)
 340 {
 341         struct ll_inode_info *lli = ll_i2info(sai->sai_inode);
 342         struct ll_sai_entry  *se;
 343         ENTRY;
 344
 345         ll_sai_entry_cleanup(entry, 0);
 346
 347         spin_lock(&lli->lli_lock);
 348         if (!list_empty(&entry->se_list))
 349                 list_del_init(&entry->se_list);
 350
 351         if (unlikely(entry->se_index < sai->sai_index_next)) {
 352                 spin_unlock(&lli->lli_lock);
 353                 OBD_FREE_PTR(entry);
 354                 RETURN(0);
 355         }
 356
 357         list_for_each_entry_reverse(se, &sai->sai_entries_stated, se_list) {
 358                 if (se->se_index < entry->se_index) {
 359                         list_add(&entry->se_list, &se->se_list);
 360                         spin_unlock(&lli->lli_lock);
 361                         RETURN(1);
 362                 }
 363         }
 364
 365         /*
 366          * I am the first entry.
 367          */
 368         list_add(&entry->se_list, &sai->sai_entries_stated);
 369         spin_unlock(&lli->lli_lock);
 370         RETURN(1);
 371 }
 372
 373 /**
 374  * finish lookup/revalidate.
 375  */
 376 static int do_statahead_interpret(struct ll_statahead_info *sai)
 377 {
 378         struct ll_inode_info   *lli = ll_i2info(sai->sai_inode);
 379         struct ll_sai_entry    *entry;
 380         struct ptlrpc_request  *req;
 381         struct md_enqueue_info *minfo;
 382         struct lookup_intent   *it;
 383         struct dentry          *dentry;
 384         int                     rc = 0;
 385         struct mdt_body        *body;
 386         ENTRY;
 387
 388         spin_lock(&lli->lli_lock);
 389         LASSERT(!sa_received_empty(sai));
 390         entry = list_entry(sai->sai_entries_received.next, struct ll_sai_entry,
 391                            se_list);
 392         list_del_init(&entry->se_list);
 393         spin_unlock(&lli->lli_lock);
 394
 395         if (unlikely(entry->se_index < sai->sai_index_next)) {
 396                 CWARN("Found stale entry: [index %u] [next %u]\n",
 397                       entry->se_index, sai->sai_index_next);
 398                 ll_sai_entry_cleanup(entry, 1);
 399                 RETURN(0);
 400         }
 401
 402         if (entry->se_stat != SA_ENTRY_STATED)
 403                 GOTO(out, rc = entry->se_stat);
 404
 405         req = entry->se_req;
 406         minfo = entry->se_minfo;
 407         it = &minfo->mi_it;
 408         dentry = minfo->mi_dentry;
 409
 410         body = req_capsule_server_get(&req->rq_pill, &RMF_MDT_BODY);
 411         if (body == NULL)
 412                 GOTO(out, rc = -EFAULT);
 413
 414         if (dentry->d_inode == NULL) {
 415                 /*
 416                  * lookup.
 417                  */
 418                 struct dentry    *save = dentry;
 419                 struct it_cb_data icbd = {
 420                         .icbd_parent   = minfo->mi_dir,
 421                         .icbd_childp   = &dentry
 422                 };
 423
 424                 LASSERT(fid_is_zero(&minfo->mi_data.op_fid2));
 425
 426                 /*
 427                  * XXX: No fid in reply, this is probaly cross-ref case.
 428                  * SA can't handle it yet.
 429                  */
 430                 if (body->valid & OBD_MD_MDS)
 431                         GOTO(out, rc = -EAGAIN);
 432
 433                 rc = ll_lookup_it_finish(req, it, &icbd);
 434                 if (!rc)
 435                         /*
 436                          * Here dentry->d_inode might be NULL,
 437                          * because the entry may have been removed before
 438                          * we start doing stat ahead.
 439                          */
 440                         ll_lookup_finish_locks(it, dentry);
 441
 442                 if (dentry != save) {
 443                         minfo->mi_dentry = dentry;
 444                         dput(save);
 445                 }
 446         } else {
 447                 /*
 448                  * revalidate.
 449                  */
 450                 if (!lu_fid_eq(&minfo->mi_data.op_fid2, &body->fid1)) {
 451                         ll_unhash_aliases(dentry->d_inode);
 452                         GOTO(out, rc = -EAGAIN);
 453                 }
 454
 455                 rc = ll_revalidate_it_finish(req, it, dentry);
 456                 if (rc) {
 457                         ll_unhash_aliases(dentry->d_inode);
 458                         GOTO(out, rc);
 459                 }
 460
 461                 spin_lock(&ll_lookup_lock);
 462                 spin_lock(&dcache_lock);
 463                 lock_dentry(dentry);
 464                 __d_drop(dentry);
 465                 dentry->d_flags &= ~DCACHE_LUSTRE_INVALID;
 466                 unlock_dentry(dentry);
 467                 d_rehash_cond(dentry, 0);
 468                 spin_unlock(&dcache_lock);
 469                 spin_unlock(&ll_lookup_lock);
 470
 471                 ll_lookup_finish_locks(it, dentry);
 472         }
 473         EXIT;
 474
 475 out:
 476         if (likely(ll_sai_entry_to_stated(sai, entry)))
 477                 cfs_waitq_signal(&sai->sai_waitq);
 478         return rc;
 479 }
 480
 481 static int ll_statahead_interpret(struct ptlrpc_request *req,
 482                                   struct md_enqueue_info *minfo,
 483                                   int rc)
 484 {
 485         struct lookup_intent     *it = &minfo->mi_it;
 486         struct dentry            *dentry = minfo->mi_dentry;
 487         struct inode             *dir = minfo->mi_dir;
 488         struct ll_inode_info     *lli = ll_i2info(dir);
 489         struct ll_statahead_info *sai;
 490         struct ll_sai_entry      *entry;
 491         ENTRY;
 492
 493         CDEBUG(D_READA, "interpret statahead %.*s rc %d\n",
 494                dentry->d_name.len, dentry->d_name.name, rc);
 495
 496         spin_lock(&lli->lli_lock);
 497         if (unlikely(lli->lli_sai == NULL ||
 498             lli->lli_sai->sai_generation != minfo->mi_generation)) {
 499                 spin_unlock(&lli->lli_lock);
 500                 ll_intent_release(it);
 501                 dput(dentry);
 502                 iput(dir);
 503                 OBD_FREE_PTR(minfo);
 504                 RETURN(-ESTALE);
 505         } else {
 506                 sai = ll_sai_get(lli->lli_sai);
 507                 entry = ll_sai_entry_set(sai,
 508                                          (unsigned int)(long)minfo->mi_cbdata,
 509                                          rc ? SA_ENTRY_UNSTATED :
 510                                          SA_ENTRY_STATED, req, minfo);
 511                 LASSERT(entry != NULL);
 512                 if (likely(sa_is_running(sai))) {
 513                         ll_sai_entry_to_received(sai, entry);
 514                         sai->sai_replied++;
 515                         spin_unlock(&lli->lli_lock);
 516                         cfs_waitq_signal(&sai->sai_thread.t_ctl_waitq);
 517                 } else {
 518                         if (!list_empty(&entry->se_list))
 519                                 list_del_init(&entry->se_list);
 520                         sai->sai_replied++;
 521                         spin_unlock(&lli->lli_lock);
 522                         ll_sai_entry_cleanup(entry, 1);
 523                 }
 524                 ll_sai_put(sai);
 525                 RETURN(rc);
 526         }
 527 }
 528
 529 static void sa_args_fini(struct md_enqueue_info *minfo,
 530                          struct ldlm_enqueue_info *einfo)
 531 {
 532         LASSERT(minfo && einfo);
 533         iput(minfo->mi_dir);
 534         capa_put(minfo->mi_data.op_capa1);
 535         capa_put(minfo->mi_data.op_capa2);
 536         OBD_FREE_PTR(minfo);
 537         OBD_FREE_PTR(einfo);
 538 }
 539
 540 /**
 541  * There is race condition between "capa_put" and "ll_statahead_interpret" for
 542  * accessing "op_data.op_capa[1,2]" as following:
 543  * "capa_put" releases "op_data.op_capa[1,2]"'s reference count after calling
 544  * "md_intent_getattr_async". But "ll_statahead_interpret" maybe run first, and
 545  * fill "op_data.op_capa[1,2]" as POISON, then cause "capa_put" access invalid
 546  * "ocapa". So here reserve "op_data.op_capa[1,2]" in "pcapa" before calling
 547  * "md_intent_getattr_async".
 548  */
 549 static int sa_args_init(struct inode *dir, struct dentry *dentry,
 550                         struct md_enqueue_info **pmi,
 551                         struct ldlm_enqueue_info **pei,
 552                         struct obd_capa **pcapa)
 553 {
 554         struct ll_inode_info     *lli = ll_i2info(dir);
 555         struct md_enqueue_info   *minfo;
 556         struct ldlm_enqueue_info *einfo;
 557         struct md_op_data        *op_data;
 558
 559         OBD_ALLOC_PTR(einfo);
 560         if (einfo == NULL)
 561                 return -ENOMEM;
 562
 563         OBD_ALLOC_PTR(minfo);
 564         if (minfo == NULL) {
 565                 OBD_FREE_PTR(einfo);
 566                 return -ENOMEM;
 567         }
 568
 569         op_data = ll_prep_md_op_data(&minfo->mi_data, dir, dentry->d_inode,
 570                                      dentry->d_name.name, dentry->d_name.len,
 571                                      0, LUSTRE_OPC_ANY, NULL);
 572         if (IS_ERR(op_data)) {
 573                 OBD_FREE_PTR(einfo);
 574                 OBD_FREE_PTR(minfo);
 575                 return PTR_ERR(op_data);
 576         }
 577
 578         minfo->mi_it.it_op = IT_GETATTR;
 579         minfo->mi_dentry = dentry;
 580         minfo->mi_dir = igrab(dir);
 581         minfo->mi_cb = ll_statahead_interpret;
 582         minfo->mi_generation = lli->lli_sai->sai_generation;
 583         minfo->mi_cbdata = (void *)(long)lli->lli_sai->sai_index;
 584
 585         einfo->ei_type   = LDLM_IBITS;
 586         einfo->ei_mode   = it_to_lock_mode(&minfo->mi_it);
 587         einfo->ei_cb_bl  = ll_md_blocking_ast;
 588         einfo->ei_cb_cp  = ldlm_completion_ast;
 589         einfo->ei_cb_gl  = NULL;
 590         einfo->ei_cbdata = NULL;
 591
 592         *pmi = minfo;
 593         *pei = einfo;
 594         pcapa[0] = op_data->op_capa1;
 595         pcapa[1] = op_data->op_capa2;
 596
 597         return 0;
 598 }
 599
 600 /**
 601  * similar to ll_lookup_it().
 602  */
 603 static int do_sa_lookup(struct inode *dir, struct dentry *dentry)
 604 {
 605         struct md_enqueue_info   *minfo;
 606         struct ldlm_enqueue_info *einfo;
 607         struct obd_capa          *capas[2];
 608         int                       rc;
 609         ENTRY;
 610
 611         rc = sa_args_init(dir, dentry, &minfo, &einfo, capas);
 612         if (rc)
 613                 RETURN(rc);
 614
 615         rc = md_intent_getattr_async(ll_i2mdexp(dir), minfo, einfo);
 616         if (!rc) {
 617                 capa_put(capas[0]);
 618                 capa_put(capas[1]);
 619         } else {
 620                 sa_args_fini(minfo, einfo);
 621         }
 622
 623         RETURN(rc);
 624 }
 625
 626 /**
 627  * similar to ll_revalidate_it().
 628  * \retval      1 -- dentry valid
 629  * \retval      0 -- will send stat-ahead request
 630  * \retval others -- prepare stat-ahead request failed
 631  */
 632 static int do_sa_revalidate(struct inode *dir, struct dentry *dentry)
 633 {
 634         struct inode             *inode = dentry->d_inode;
 635         struct lookup_intent      it = { .it_op = IT_GETATTR };
 636         struct md_enqueue_info   *minfo;
 637         struct ldlm_enqueue_info *einfo;
 638         struct obd_capa          *capas[2];
 639         int rc;
 640         ENTRY;
 641
 642         if (inode == NULL)
 643                 RETURN(1);
 644
 645         if (d_mountpoint(dentry))
 646                 RETURN(1);
 647
 648         if (dentry == dentry->d_sb->s_root)
 649                 RETURN(1);
 650
 651         rc = md_revalidate_lock(ll_i2mdexp(dir), &it, ll_inode2fid(inode));
 652         if (rc == 1) {
 653                 ll_intent_release(&it);
 654                 RETURN(1);
 655         }
 656
 657         rc = sa_args_init(dir, dentry, &minfo, &einfo, capas);
 658         if (rc)
 659                 RETURN(rc);
 660
 661         rc = md_intent_getattr_async(ll_i2mdexp(dir), minfo, einfo);
 662         if (!rc) {
 663                 capa_put(capas[0]);
 664                 capa_put(capas[1]);
 665         } else {
 666                 sa_args_fini(minfo, einfo);
 667         }
 668
 669         RETURN(rc);
 670 }
 671
 672 static inline void ll_name2qstr(struct qstr *q, const char *name, int namelen)
 673 {
 674         q->name = name;
 675         q->len  = namelen;
 676         q->hash = full_name_hash(name, namelen);
 677 }
 678
 679 static int ll_statahead_one(struct dentry *parent, const char* entry_name,
 680                             int entry_name_len)
 681 {
 682         struct inode             *dir = parent->d_inode;
 683         struct ll_inode_info     *lli = ll_i2info(dir);
 684         struct ll_statahead_info *sai = lli->lli_sai;
 685         struct qstr               name;
 686         struct dentry            *dentry;
 687         struct ll_sai_entry      *se;
 688         int                       rc;
 689         ENTRY;
 690
 691         if (parent->d_flags & DCACHE_LUSTRE_INVALID) {
 692                 CDEBUG(D_READA, "parent dentry@%p %.*s is "
 693                        "invalid, skip statahead\n",
 694                        parent, parent->d_name.len, parent->d_name.name);
 695                 RETURN(-EINVAL);
 696         }
 697
 698         se = ll_sai_entry_init(sai, sai->sai_index);
 699         if (IS_ERR(se))
 700                 RETURN(PTR_ERR(se));
 701
 702         ll_name2qstr(&name, entry_name, entry_name_len);
 703         dentry = d_lookup(parent, &name);
 704         if (!dentry) {
 705                 dentry = d_alloc(parent, &name);
 706                 if (dentry) {
 707                         rc = do_sa_lookup(dir, dentry);
 708                         if (rc)
 709                                 dput(dentry);
 710                 } else {
 711                         GOTO(out, rc = -ENOMEM);
 712                 }
 713         } else {
 714                 rc = do_sa_revalidate(dir, dentry);
 715                 if (rc)
 716                         dput(dentry);
 717         }
 718
 719         EXIT;
 720
 721 out:
 722         if (rc) {
 723                 CDEBUG(D_READA, "set sai entry %p index %u stat %d rc %d\n",
 724                        se, se->se_index, se->se_stat, rc);
 725                 se->se_stat = rc;
 726                 if (ll_sai_entry_to_stated(sai, se))
 727                         cfs_waitq_signal(&sai->sai_waitq);
 728         } else {
 729                 sai->sai_sent++;
 730         }
 731
 732         sai->sai_index++;
 733         return rc;
 734 }
 735
 736 static int ll_statahead_thread(void *arg)
 737 {
 738         struct dentry            *parent = (struct dentry *)arg;
 739         struct inode             *dir = parent->d_inode;
 740         struct ll_inode_info     *lli = ll_i2info(dir);
 741         struct ll_sb_info        *sbi = ll_i2sbi(dir);
 742         struct ll_statahead_info *sai = ll_sai_get(lli->lli_sai);
 743         struct ptlrpc_thread     *thread = &sai->sai_thread;
 744         struct page              *page;
 745         __u64                     pos = 0;
 746         int                       first = 0;
 747         int                       rc = 0;
 748         struct ll_dir_chain       chain;
 749         ENTRY;
 750
 751         {
 752                 char pname[16];
 753                 snprintf(pname, 15, "ll_sa_%u", lli->lli_opendir_pid);
 754                 cfs_daemonize(pname);
 755         }
 756
 757         sbi->ll_sa_total++;
 758         spin_lock(&lli->lli_lock);
 759         thread->t_flags = SVC_RUNNING;
 760         spin_unlock(&lli->lli_lock);
 761         cfs_waitq_signal(&thread->t_ctl_waitq);
 762         CDEBUG(D_READA, "start doing statahead for %s\n", parent->d_name.name);
 763
 764         ll_dir_chain_init(&chain);
 765         page = ll_get_dir_page(dir, pos, 0, &chain);
 766
 767         while (1) {
 768                 struct l_wait_info lwi = { 0 };
 769                 struct lu_dirpage *dp;
 770                 struct lu_dirent  *ent;
 771
 772                 if (IS_ERR(page)) {
 773                         rc = PTR_ERR(page);
 774                         CERROR("error reading dir "DFID" at "LPU64"/%u: rc %d\n",
 775                                PFID(ll_inode2fid(dir)), pos,
 776                                sai->sai_index, rc);
 777                         break;
 778                 }
 779
 780                 dp = page_address(page);
 781                 for (ent = lu_dirent_start(dp); ent != NULL;
 782                      ent = lu_dirent_next(ent)) {
 783                         char *name = ent->lde_name;
 784                         int namelen = le16_to_cpu(ent->lde_namelen);
 785
 786                         if (namelen == 0)
 787                                 /*
 788                                  * Skip dummy record.
 789                                  */
 790                                 continue;
 791
 792                         if (name[0] == '.') {
 793                                 if (namelen == 1) {
 794                                         /*
 795                                          * skip "."
 796                                          */
 797                                         continue;
 798                                 } else if (name[1] == '.' && namelen == 2) {
 799                                         /*
 800                                          * skip ".."
 801                                          */
 802                                         continue;
 803                                 } else if (!sai->sai_ls_all) {
 804                                         /*
 805                                          * skip hidden files.
 806                                          */
 807                                         sai->sai_skip_hidden++;
 808                                         continue;
 809                                 }
 810                         }
 811
 812                         /*
 813                          * don't stat-ahead first entry.
 814                          */
 815                         if (unlikely(!first)) {
 816                                 first++;
 817                                 continue;
 818                         }
 819
 820 keep_de:
 821                         l_wait_event(thread->t_ctl_waitq,
 822                                      !sa_is_running(sai) || sa_not_full(sai) ||
 823                                      !sa_received_empty(sai),
 824                                      &lwi);
 825
 826                         while (!sa_received_empty(sai) && sa_is_running(sai))
 827                                 do_statahead_interpret(sai);
 828
 829                         if (unlikely(!sa_is_running(sai))) {
 830                                 ll_put_page(page);
 831                                 GOTO(out, rc);
 832                         }
 833
 834                         if (!sa_not_full(sai))
 835                                 /*
 836                                  * do not skip the current de.
 837                                  */
 838                                 goto keep_de;
 839
 840                         rc = ll_statahead_one(parent, name, namelen);
 841                         if (rc < 0) {
 842                                 ll_put_page(page);
 843                                 GOTO(out, rc);
 844                         }
 845                 }
 846                 pos = le64_to_cpu(dp->ldp_hash_end);
 847                 ll_put_page(page);
 848                 if (pos == DIR_END_OFF) {
 849                         /*
 850                          * End of directory reached.
 851                          */
 852                         while (1) {
 853                                 l_wait_event(thread->t_ctl_waitq,
 854                                              !sa_is_running(sai) ||
 855                                              !sa_received_empty(sai) ||
 856                                              sai->sai_sent == sai->sai_replied,
 857                                              &lwi);
 858                                 if (!sa_received_empty(sai) &&
 859                                     sa_is_running(sai))
 860                                         do_statahead_interpret(sai);
 861                                 else
 862                                         GOTO(out, rc);
 863                         }
 864                 } else if (1) {
 865                         /*
 866                          * chain is exhausted.
 867                          * Normal case: continue to the next page.
 868                          */
 869                         page = ll_get_dir_page(dir, pos, 1, &chain);
 870                 } else {
 871                         /*
 872                          * go into overflow page.
 873                          */
 874                 }
 875         }
 876         EXIT;
 877
 878 out:
 879         ll_dir_chain_fini(&chain);
 880         spin_lock(&lli->lli_lock);
 881         thread->t_flags = SVC_STOPPED;
 882         spin_unlock(&lli->lli_lock);
 883         cfs_waitq_signal(&sai->sai_waitq);
 884         cfs_waitq_signal(&thread->t_ctl_waitq);
 885         ll_sai_put(sai);
 886         dput(parent);
 887         CDEBUG(D_READA, "statahead thread stopped, pid %d\n",
 888                cfs_curproc_pid());
 889         return rc;
 890 }
 891
 892 /**
 893  * called in ll_file_release().
 894  */
 895 void ll_stop_statahead(struct inode *inode, void *key)
 896 {
 897         struct ll_inode_info *lli = ll_i2info(inode);
 898
 899         if (unlikely(key == NULL))
 900                 return;
 901
 902         spin_lock(&lli->lli_lock);
 903         if (lli->lli_opendir_key != key || lli->lli_opendir_pid == 0) {
 904                 spin_unlock(&lli->lli_lock);
 905                 return;
 906         }
 907
 908         lli->lli_opendir_key = NULL;
 909
 910         if (lli->lli_sai) {
 911                 struct l_wait_info lwi = { 0 };
 912                 struct ptlrpc_thread *thread = &lli->lli_sai->sai_thread;
 913
 914                 if (!sa_is_stopped(lli->lli_sai)) {
 915                         thread->t_flags = SVC_STOPPING;
 916                         spin_unlock(&lli->lli_lock);
 917                         cfs_waitq_signal(&thread->t_ctl_waitq);
 918
 919                         CDEBUG(D_READA, "stopping statahead thread, pid %d\n",
 920                                cfs_curproc_pid());
 921                         l_wait_event(thread->t_ctl_waitq,
 922                                      sa_is_stopped(lli->lli_sai),
 923                                      &lwi);
 924                 } else {
 925                         spin_unlock(&lli->lli_lock);
 926                 }
 927
 928                 /*
 929                  * Put the ref which was held when first statahead_enter.
 930                  * It maybe not the last ref for some statahead requests
 931                  * maybe inflight.
 932                  */
 933                 ll_sai_put(lli->lli_sai);
 934         } else {
 935                 lli->lli_opendir_pid = 0;
 936                 spin_unlock(&lli->lli_lock);
 937         }
 938 }
 939
 940 enum {
 941         /**
 942          * not first dirent, or is "."
 943          */
 944         LS_NONE_FIRST_DE = 0,
 945         /**
 946          * the first non-hidden dirent
 947          */
 948         LS_FIRST_DE,
 949         /**
 950          * the first hidden dirent, that is "."
 951          */
 952         LS_FIRST_DOT_DE
 953 };
 954
 955 static int is_first_dirent(struct inode *dir, struct dentry *dentry)
 956 {
 957         struct ll_dir_chain chain;
 958         struct qstr        *target = &dentry->d_name;
 959         struct page        *page;
 960         __u64               pos = 0;
 961         int                 dot_de;
 962         int                 rc = LS_NONE_FIRST_DE;
 963         ENTRY;
 964
 965         ll_dir_chain_init(&chain);
 966         page = ll_get_dir_page(dir, pos, 0, &chain);
 967
 968         while (1) {
 969                 struct lu_dirpage *dp;
 970                 struct lu_dirent  *ent;
 971
 972                 if (IS_ERR(page)) {
 973                         rc = PTR_ERR(page);
 974                         CERROR("error reading dir "DFID" at "LPU64": rc %d\n",
 975                                PFID(ll_inode2fid(dir)), pos, rc);
 976                         break;
 977                 }
 978
 979                 dp = page_address(page);
 980                 for (ent = lu_dirent_start(dp); ent != NULL;
 981                      ent = lu_dirent_next(ent)) {
 982                         char *name = ent->lde_name;
 983                         int namelen = le16_to_cpu(ent->lde_namelen);
 984
 985                         if (namelen == 0)
 986                                 /*
 987                                  * skip dummy record.
 988                                  */
 989                                 continue;
 990
 991                         if (name[0] == '.') {
 992                                 if (namelen == 1)
 993                                         /*
 994                                          * skip "."
 995                                          */
 996                                         continue;
 997                                 else if (name[1] == '.' && namelen == 2)
 998                                         /*
 999                                          * skip ".."
1000                                          */
1001                                         continue;
1002                                 else
1003                                         dot_de = 1;
1004                         } else {
1005                                 dot_de = 0;
1006                         }
1007
1008                         if (dot_de && target->name[0] != '.') {
1009                                 CDEBUG(D_READA, "%.*s skip hidden file %.*s\n",
1010                                        target->len, target->name,
1011                                        namelen, name);
1012                                 continue;
1013                         }
1014
1015                         if (target->len != namelen ||
1016                             memcmp(target->name, name, namelen) != 0)
1017                                 rc = LS_NONE_FIRST_DE;
1018                         else if (!dot_de)
1019                                 rc = LS_FIRST_DE;
1020                         else
1021                                 rc = LS_FIRST_DOT_DE;
1022
1023                         ll_put_page(page);
1024                         GOTO(out, rc);
1025                 }
1026                 pos = le64_to_cpu(dp->ldp_hash_end);
1027                 ll_put_page(page);
1028                 if (pos == DIR_END_OFF) {
1029                         /*
1030                          * End of directory reached.
1031                          */
1032                         break;
1033                 } else if (1) {
1034                         /*
1035                          * chain is exhausted
1036                          * Normal case: continue to the next page.
1037                          */
1038                         page = ll_get_dir_page(dir, pos, 1, &chain);
1039                 } else {
1040                         /*
1041                          * go into overflow page.
1042                          */
1043                 }
1044         }
1045         EXIT;
1046
1047 out:
1048         ll_dir_chain_fini(&chain);
1049         return rc;
1050 }
1051
1052 /**
1053  * Start statahead thread if this is the first dir entry.
1054  * Otherwise if a thread is started already, wait it until it is ahead of me.
1055  * \retval 0       -- stat ahead thread process such dentry, for lookup, it miss
1056  * \retval 1       -- stat ahead thread process such dentry, for lookup, it hit
1057  * \retval -EEXIST -- stat ahead thread started, and this is the first dentry
1058  * \retval -EBADFD -- statahead thread exit and not dentry available
1059  * \retval -EAGAIN -- try to stat by caller
1060  * \retval others  -- error
1061  */
1062 int do_statahead_enter(struct inode *dir, struct dentry **dentryp, int lookup)
1063 {
1064         struct ll_inode_info     *lli;
1065         struct ll_statahead_info *sai;
1066         struct dentry            *parent;
1067         struct l_wait_info        lwi = LWI_INTR(LWI_ON_SIGNAL_NOOP, NULL);
1068         int                       rc = 0;
1069         ENTRY;
1070
1071         LASSERT(dir != NULL);
1072         lli = ll_i2info(dir);
1073         LASSERT(lli->lli_opendir_pid == cfs_curproc_pid());
1074         sai = lli->lli_sai;
1075
1076         if (sai) {
1077                 struct ll_sb_info *sbi;
1078
1079                 if (unlikely(sa_is_stopped(sai) &&
1080                              list_empty(&sai->sai_entries_stated)))
1081                         RETURN(-EBADFD);
1082
1083                 if ((*dentryp)->d_name.name[0] == '.') {
1084                         if (likely(sai->sai_ls_all ||
1085                             sai->sai_miss_hidden >= sai->sai_skip_hidden)) {
1086                                 /*
1087                                  * Hidden dentry is the first one, or statahead
1088                                  * thread does not skip so many hidden dentries
1089                                  * before "sai_ls_all" enabled as below.
1090                                  */
1091                         } else {
1092                                 if (!sai->sai_ls_all)
1093                                         /*
1094                                          * It maybe because hidden dentry is not
1095                                          * the first one, "sai_ls_all" was not
1096                                          * set, then "ls -al" missed. Enable
1097                                          * "sai_ls_all" for such case.
1098                                          */
1099                                         sai->sai_ls_all = 1;
1100
1101                                 /*
1102                                  * Such "getattr" has been skipped before
1103                                  * "sai_ls_all" enabled as above.
1104                                  */
1105                                 sai->sai_miss_hidden++;
1106                                 RETURN(-ENOENT);
1107                         }
1108                 }
1109
1110                 sbi = ll_i2sbi(dir);
1111                 if (ll_sai_entry_stated(sai)) {
1112                         sbi->ll_sa_cached++;
1113                 } else {
1114                         sbi->ll_sa_blocked++;
1115                         /*
1116                          * thread started already, avoid double-stat.
1117                          */
1118                         rc = l_wait_event(sai->sai_waitq,
1119                                           ll_sai_entry_stated(sai) ||
1120                                           sa_is_stopped(sai),
1121                                           &lwi);
1122                 }
1123
1124                 if (lookup) {
1125                         struct dentry *result;
1126
1127                         result = d_lookup((*dentryp)->d_parent,
1128                                           &(*dentryp)->d_name);
1129                         if (result) {
1130                                 LASSERT(result != *dentryp);
1131                                 /* BUG 16303: do not drop reference count for
1132                                  * "*dentryp", VFS will do that by itself. */
1133                                 *dentryp = result;
1134                                 RETURN(1);
1135                         }
1136                 }
1137                 /*
1138                  * do nothing for revalidate.
1139                  */
1140                 RETURN(rc);
1141         }
1142
1143         /* I am the "lli_opendir_pid" owner, only me can set "lli_sai". */
1144         rc = is_first_dirent(dir, *dentryp);
1145         if (rc == LS_NONE_FIRST_DE)
1146                 /* It is not "ls -{a}l" operation, no need statahead for it. */
1147                 GOTO(out, rc = -EAGAIN);
1148
1149         sai = ll_sai_alloc();
1150         if (sai == NULL)
1151                 GOTO(out, rc = -ENOMEM);
1152
1153         sai->sai_ls_all = (rc == LS_FIRST_DOT_DE);
1154         sai->sai_inode = igrab(dir);
1155         if (unlikely(sai->sai_inode == NULL)) {
1156                 CWARN("Do not start stat ahead on dying inode "DFID" .\n",
1157                       PFID(&lli->lli_fid));
1158                 OBD_FREE_PTR(sai);
1159                 GOTO(out, rc = -ESTALE);
1160         }
1161
1162         /* get parent reference count here, and put it in ll_statahead_thread */
1163         parent = dget((*dentryp)->d_parent);
1164         if (unlikely(sai->sai_inode != parent->d_inode)) {
1165                 struct ll_inode_info *nlli = ll_i2info(parent->d_inode);
1166
1167                 CWARN("Race condition, someone changed %.*s just now: "
1168                       "old parent "DFID", new parent "DFID" .\n",
1169                       (*dentryp)->d_name.len, (*dentryp)->d_name.name,
1170                       PFID(&lli->lli_fid), PFID(&nlli->lli_fid));
1171                 dput(parent);
1172                 iput(sai->sai_inode);
1173                 OBD_FREE_PTR(sai);
1174                 RETURN(-EAGAIN);
1175         }
1176
1177         lli->lli_sai = sai;
1178         rc = cfs_kernel_thread(ll_statahead_thread, parent, 0);
1179         if (rc < 0) {
1180                 CERROR("can't start ll_sa thread, rc: %d\n", rc);
1181                 dput(parent);
1182                 lli->lli_opendir_key = NULL;
1183                 sai->sai_thread.t_flags = SVC_STOPPED;
1184                 ll_sai_put(sai);
1185                 LASSERT(lli->lli_sai == NULL);
1186                 RETURN(-EAGAIN);
1187         }
1188
1189         l_wait_event(sai->sai_thread.t_ctl_waitq,
1190                      sa_is_running(sai) || sa_is_stopped(sai),
1191                      &lwi);
1192
1193         /*
1194          * We don't stat-ahead for the first dirent since we are already in
1195          * lookup, and -EEXIST also indicates that this is the first dirent.
1196          */
1197         RETURN(-EEXIST);
1198
1199 out:
1200         spin_lock(&lli->lli_lock);
1201         lli->lli_opendir_key = NULL;
1202         lli->lli_opendir_pid = 0;
1203         spin_unlock(&lli->lli_lock);
1204         return rc;
1205 }
1206
1207 /**
1208  * update hit/miss count.
1209  */
1210 void ll_statahead_exit(struct inode *dir, struct dentry *dentry, int result)
1211 {
1212         struct ll_inode_info     *lli;
1213         struct ll_statahead_info *sai;
1214         struct ll_sb_info        *sbi;
1215         struct ll_dentry_data    *ldd = ll_d2d(dentry);
1216         ENTRY;
1217
1218         LASSERT(dir != NULL);
1219         lli = ll_i2info(dir);
1220         LASSERT(lli->lli_opendir_pid == cfs_curproc_pid());
1221         sai = lli->lli_sai;
1222         LASSERT(sai != NULL);
1223         sbi = ll_i2sbi(dir);
1224
1225         if (result >= 1) {
1226                 sbi->ll_sa_hit++;
1227                 sai->sai_hit++;
1228                 sai->sai_consecutive_miss = 0;
1229                 sai->sai_max = min(2 * sai->sai_max, sbi->ll_sa_max);
1230         } else {
1231                 sbi->ll_sa_miss++;
1232                 sai->sai_miss++;
1233                 sai->sai_consecutive_miss++;
1234                 if (sa_low_hit(sai) && sa_is_running(sai)) {
1235                         sbi->ll_sa_wrong++;
1236                         CDEBUG(D_READA, "Statahead for dir "DFID" hit ratio "
1237                                "too low: hit/miss %u/%u, sent/replied %u/%u, "
1238                                "stopping statahead thread: pid %d\n",
1239                                PFID(&lli->lli_fid), sai->sai_hit,
1240                                sai->sai_miss, sai->sai_sent,
1241                                sai->sai_replied, cfs_curproc_pid());
1242                         spin_lock(&lli->lli_lock);
1243                         if (!sa_is_stopped(sai))
1244                                 sai->sai_thread.t_flags = SVC_STOPPING;
1245                         spin_unlock(&lli->lli_lock);
1246                 }
1247         }
1248
1249         if (!sa_is_stopped(sai))
1250                 cfs_waitq_signal(&sai->sai_thread.t_ctl_waitq);
1251         ll_sai_entry_fini(sai);
1252         if (likely(ldd != NULL))
1253                 ldd->lld_sa_generation = sai->sai_generation;
1254
1255         EXIT;
1256 }