lustre/llite/statahead.c

   1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
   2  * vim:expandtab:shiftwidth=8:tabstop=8:
   3  *
   4  *  Copyright (c) 2007 Cluster File Systems, Inc.
   5  *
   6  *   This file is part of Lustre, http://www.lustre.org.
   7  *
   8  *   Lustre is free software; you can redistribute it and/or
   9  *   modify it under the terms of version 2 of the GNU General Public
  10  *   License as published by the Free Software Foundation.
  11  *
  12  *   Lustre is distributed in the hope that it will be useful,
  13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *   GNU General Public License for more details.
  16  *
  17  *   You should have received a copy of the GNU General Public License
  18  *   along with Lustre; if not, write to the Free Software
  19  *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  */
  21
  22 #include <linux/fs.h>
  23 #include <linux/sched.h>
  24 #include <linux/mm.h>
  25 #include <linux/smp_lock.h>
  26 #include <linux/highmem.h>
  27 #include <linux/pagemap.h>
  28
  29 #define DEBUG_SUBSYSTEM S_LLITE
  30
  31 #include <obd_support.h>
  32 #include <lustre_lite.h>
  33 #include <lustre_dlm.h>
  34 #include <linux/lustre_version.h>
  35 #include "llite_internal.h"
  36
  37 struct ll_sai_entry {
  38         struct list_head        se_list;
  39         int                     se_index;
  40         int                     se_stat;
  41 };
  42
  43 enum {
  44         SA_ENTRY_UNSTATED = 0,
  45         SA_ENTRY_STATED
  46 };
  47
  48 static struct ll_statahead_info *ll_sai_alloc(void)
  49 {
  50         struct ll_statahead_info *sai;
  51
  52         OBD_ALLOC_PTR(sai);
  53         if (!sai)
  54                 return NULL;
  55
  56         sai->sai_max = LL_STATAHEAD_MIN;
  57         init_waitqueue_head(&sai->sai_thread.t_ctl_waitq);
  58         INIT_LIST_HEAD(&sai->sai_entries);
  59         atomic_set(&sai->sai_refc, 1);
  60         return sai;
  61 }
  62
  63 static inline
  64 struct ll_statahead_info *ll_sai_get(struct ll_statahead_info *sai)
  65 {
  66         LASSERT(sai);
  67         atomic_inc(&sai->sai_refc);
  68         return sai;
  69 }
  70
  71 static void ll_sai_put(struct ll_statahead_info *sai)
  72 {
  73         struct inode *inode = sai->sai_inode;
  74         struct ll_inode_info *lli = ll_i2info(inode);
  75         ENTRY;
  76
  77         if (atomic_dec_and_lock(&sai->sai_refc, &lli->lli_lock)) {
  78                 struct ll_sai_entry  *entry, *next;
  79
  80                 LASSERT(sai->sai_thread.t_flags & SVC_STOPPED);
  81                 list_for_each_entry_safe(entry, next, &sai->sai_entries,
  82                                          se_list) {
  83                         list_del(&entry->se_list);
  84                         OBD_FREE_PTR(entry);
  85                 }
  86                 OBD_FREE_PTR(sai);
  87                 lli->lli_sai = NULL;
  88                 spin_unlock(&lli->lli_lock);
  89                 iput(inode);
  90         }
  91         EXIT;
  92 }
  93
  94 static struct ll_sai_entry *ll_sai_entry_get(struct ll_statahead_info *sai,
  95                                              int index, int stat)
  96 {
  97         struct ll_inode_info *lli = ll_i2info(sai->sai_inode);
  98         struct ll_sb_info    *sbi = ll_i2sbi(sai->sai_inode);
  99         struct ll_sai_entry  *entry;
 100         ENTRY;
 101
 102         OBD_ALLOC_PTR(entry);
 103         if (entry == NULL)
 104                 RETURN(NULL);
 105
 106         CDEBUG(D_READA, "alloc sai entry %p index %d, stat %d\n",
 107                entry, index, stat);
 108         entry->se_index = index;
 109         entry->se_stat  = stat;
 110
 111         spin_lock(&lli->lli_lock);
 112         list_add_tail(&entry->se_list, &sai->sai_entries);
 113         sai->sai_entries_nr++;
 114         sbi->ll_sa_count = sai->sai_entries_nr;
 115         spin_unlock(&lli->lli_lock);
 116
 117         LASSERT(sai->sai_entries_nr <= sbi->ll_sa_max);
 118         RETURN(entry);
 119 }
 120
 121 static void ll_sai_entry_set(struct ll_statahead_info *sai, int index,
 122                              int stat)
 123 {
 124         struct ll_sai_entry *entry;
 125         ENTRY;
 126
 127         list_for_each_entry(entry, &sai->sai_entries, se_list) {
 128                 if (entry->se_index == index) {
 129                         LASSERT(entry->se_stat == SA_ENTRY_UNSTATED);
 130                         entry->se_stat = stat;
 131                         CDEBUG(D_READA, "set sai entry %p index %d stat %d\n",
 132                                entry, index, stat);
 133                         EXIT;
 134                         return;
 135                 }
 136         }
 137         /* Sometimes, this happens when entry has been put and freed */
 138         CDEBUG(D_READA, "can't find sai entry index %d\n", index);
 139         EXIT;
 140 }
 141
 142 /* check first entry was stated already */
 143 static int ll_sai_entry_stated(struct ll_statahead_info *sai)
 144 {
 145         struct ll_inode_info *lli = ll_i2info(sai->sai_inode);
 146         struct ll_sai_entry  *entry;
 147         int                   rc = 0;
 148         ENTRY;
 149
 150         spin_lock(&lli->lli_lock);
 151         if (!list_empty(&sai->sai_entries)) {
 152                 entry = list_entry(sai->sai_entries.next, struct ll_sai_entry,
 153                                    se_list);
 154                 CDEBUG(D_READA, "check sai entry %p index %d stat %d\n",
 155                        entry, entry->se_index, entry->se_stat);
 156                 rc = (entry->se_stat != SA_ENTRY_UNSTATED);
 157         }
 158         spin_unlock(&lli->lli_lock);
 159
 160         RETURN(rc);
 161 }
 162
 163 /* inside lli_lock */
 164 static void ll_sai_entry_put(struct ll_statahead_info *sai)
 165 {
 166         struct ll_sai_entry  *entry;
 167         ENTRY;
 168
 169         if (list_empty(&sai->sai_entries)) {
 170                 EXIT;
 171                 return;
 172         }
 173         LASSERT(sai->sai_entries_nr > 0);
 174
 175         entry = list_entry(sai->sai_entries.next, struct ll_sai_entry, se_list);
 176         list_del(&entry->se_list);
 177         sai->sai_entries_nr--;
 178
 179         CDEBUG(D_READA, "free sa entry %p index %d stat %d\n",
 180                entry, entry->se_index, entry->se_stat);
 181         OBD_FREE_PTR(entry);
 182         EXIT;
 183 }
 184
 185 /* finish lookup/revalidate */
 186 static int ll_statahead_interpret(struct obd_export *exp,
 187                                   struct ptlrpc_request *req,
 188                                   struct md_enqueue_info *minfo,
 189                                   int rc)
 190 {
 191         struct lookup_intent     *it = &minfo->mi_it;
 192         struct dentry            *dentry = minfo->mi_dentry;
 193         struct inode             *dir = dentry->d_parent->d_inode;
 194         struct ll_inode_info     *lli = ll_i2info(dir);
 195         struct ll_statahead_info *sai;
 196         ENTRY;
 197
 198         CDEBUG(D_READA, "interpret statahead %.*s rc %d\n",
 199                dentry->d_name.len, dentry->d_name.name, rc);
 200         if (rc)
 201                 GOTO(out, rc);
 202
 203         if (dentry->d_inode == NULL) {
 204                 /* lookup */
 205                 struct dentry    *save = dentry;
 206                 struct it_cb_data icbd = {
 207                         .icbd_parent = dir,
 208                         .icbd_childp = &dentry
 209                 };
 210
 211                 rc = lookup_it_finish(req, DLM_REPLY_REC_OFF, it, &icbd);
 212                 if (!rc) {
 213                         LASSERT(dentry->d_inode);
 214                         if (dentry != save)
 215                                 dput(save);
 216                         ll_lookup_finish_locks(it, dentry);
 217                 }
 218         } else {
 219                 /* revalidate */
 220                 struct mds_body *body;
 221
 222                 body = lustre_msg_buf(req->rq_repmsg, DLM_REPLY_REC_OFF,
 223                                       sizeof(*body));
 224                 if (memcmp(&minfo->mi_data.fid2, &body->fid1,
 225                            sizeof(body->fid1))) {
 226                         ll_unhash_aliases(dentry->d_inode);
 227                         GOTO(out, rc = -EAGAIN);
 228                 }
 229
 230                 rc = revalidate_it_finish(req, DLM_REPLY_REC_OFF, it, dentry);
 231                 if (rc) {
 232                         ll_unhash_aliases(dentry->d_inode);
 233                         GOTO(out, rc);
 234                 }
 235
 236                 spin_lock(&dcache_lock);
 237                 lock_dentry(dentry);
 238                 __d_drop(dentry);
 239 #ifdef DCACHE_LUSTRE_INVALID
 240                 dentry->d_flags &= ~DCACHE_LUSTRE_INVALID;
 241 #endif
 242                 unlock_dentry(dentry);
 243                 __d_rehash(dentry, 0);
 244                 spin_unlock(&dcache_lock);
 245
 246                 ll_lookup_finish_locks(it, dentry);
 247
 248         }
 249         EXIT;
 250 out:
 251         spin_lock(&lli->lli_lock);
 252         sai = lli->lli_sai;
 253         if (sai) {
 254                 lli->lli_sai->sai_replied++;
 255                 ll_sai_entry_set(lli->lli_sai, (int)minfo->mi_cbdata,
 256                                  SA_ENTRY_STATED);
 257                 wake_up(&lli->lli_sai->sai_thread.t_ctl_waitq);
 258         }
 259         spin_unlock(&lli->lli_lock);
 260         ll_intent_release(it);
 261         OBD_FREE_PTR(minfo);
 262
 263         dput(dentry);
 264         return rc;
 265 }
 266
 267 static void sa_args_fini(struct md_enqueue_info *minfo,
 268                          struct ldlm_enqueue_info *einfo)
 269 {
 270         LASSERT(minfo && einfo);
 271         OBD_FREE_PTR(minfo);
 272         OBD_FREE_PTR(einfo);
 273 }
 274
 275 static int sa_args_prep(struct inode *dir, struct dentry *dentry,
 276                         struct md_enqueue_info **pmi,
 277                         struct ldlm_enqueue_info **pei)
 278 {
 279         struct ll_inode_info     *lli = ll_i2info(dir);
 280         struct md_enqueue_info   *minfo;
 281         struct ldlm_enqueue_info *einfo;
 282
 283         OBD_ALLOC_PTR(einfo);
 284         if (einfo == NULL)
 285                 return -ENOMEM;
 286
 287         OBD_ALLOC_PTR(minfo);
 288         if (minfo == NULL) {
 289                 OBD_FREE_PTR(einfo);
 290                 return -ENOMEM;
 291         }
 292
 293         minfo->mi_exp = ll_i2mdcexp(dir);
 294         minfo->mi_it.it_op = IT_GETATTR;
 295         minfo->mi_dentry = dentry;
 296         minfo->mi_cb = ll_statahead_interpret;
 297         minfo->mi_cbdata = (void *)lli->lli_sai->sai_sent;
 298
 299         einfo->ei_type   = LDLM_IBITS;
 300         einfo->ei_mode   = it_to_lock_mode(&minfo->mi_it);
 301         einfo->ei_cb_bl  = ll_mdc_blocking_ast;
 302         einfo->ei_cb_cp  = ldlm_completion_ast;
 303         einfo->ei_cb_gl  = NULL;
 304         einfo->ei_cbdata = NULL;
 305
 306         *pmi = minfo;
 307         *pei = einfo;
 308
 309         return 0;
 310 }
 311
 312 /* similar to ll_lookup_it(). */
 313 static int do_sa_lookup(struct inode *dir, struct dentry *dentry)
 314 {
 315         struct md_enqueue_info   *minfo;
 316         struct ldlm_enqueue_info *einfo;
 317         int                       rc;
 318         ENTRY;
 319
 320         rc = sa_args_prep(dir, dentry, &minfo, &einfo);
 321         if (rc)
 322                 RETURN(rc);
 323
 324         rc = ll_prepare_mdc_op_data(&minfo->mi_data, dir, NULL,
 325                                     dentry->d_name.name, dentry->d_name.len, 0,
 326                                     NULL);
 327         if (rc == 0)
 328                 rc = mdc_intent_getattr_async(minfo->mi_exp, minfo, einfo);
 329
 330         if (rc)
 331                 sa_args_fini(minfo, einfo);
 332
 333         RETURN(rc);
 334 }
 335
 336 /* similar to ll_revalidate_it().
 337  * return 1: dentry valid.
 338  *        0: will send stat-ahead request.
 339  *        -errno: prepare stat-ahead request failed. */
 340 static int do_sa_revalidate(struct dentry *dentry)
 341 {
 342         struct inode             *inode = dentry->d_inode;
 343         struct ll_inode_info     *lli = ll_i2info(dentry->d_parent->d_inode);
 344         struct ll_fid             fid;
 345         struct lookup_intent      it = { .it_op = IT_GETATTR };
 346         struct md_enqueue_info   *minfo;
 347         struct ldlm_enqueue_info *einfo;
 348         int rc;
 349         ENTRY;
 350
 351         if (inode == NULL)
 352                 RETURN(1);
 353
 354         if (d_mountpoint(dentry))
 355                 RETURN(1);
 356
 357         ll_inode2fid(&fid, inode);
 358
 359         rc = mdc_revalidate_lock(ll_i2mdcexp(inode), &it, &fid);
 360         if (rc == 1) {
 361                 ll_intent_release(&it);
 362                 lli->lli_sai->sai_cached++;
 363                 wake_up(&lli->lli_sai->sai_thread.t_ctl_waitq);
 364                 RETURN(1);
 365         }
 366
 367         rc = sa_args_prep(dentry->d_parent->d_inode, dentry, &minfo, &einfo);
 368         if (rc)
 369                 RETURN(rc);
 370
 371         rc = ll_prepare_mdc_op_data(&minfo->mi_data, dentry->d_parent->d_inode,
 372                                     inode, dentry->d_name.name,
 373                                     dentry->d_name.len, 0, NULL);
 374         if (rc == 0)
 375                 rc = mdc_intent_getattr_async(minfo->mi_exp, minfo, einfo);
 376
 377         if (rc)
 378                 sa_args_fini(minfo, einfo);
 379
 380         RETURN(rc);
 381 }
 382
 383 /* copied from kernel */
 384 static inline void name2qstr(struct qstr *this, const char *name, int namelen)
 385 {
 386         unsigned long        hash;
 387         const unsigned char *p = (const unsigned char *)name;
 388         int                  len;
 389         unsigned int         c;
 390
 391         hash = init_name_hash();
 392         for (len = 0; len < namelen; len++, p++) {
 393                 c = *p;
 394                 hash = partial_name_hash(c, hash);
 395         }
 396         this->name = name;
 397         this->len  = namelen;
 398         this->hash = end_name_hash(hash);
 399 }
 400
 401 static int ll_statahead_one(struct dentry *parent, ext2_dirent *de)
 402 {
 403         struct inode           *dir = parent->d_inode;
 404         struct ll_inode_info   *lli = ll_i2info(dir);
 405         struct qstr             name;
 406         struct dentry          *dentry;
 407         struct ll_sai_entry    *se;
 408         int                     rc;
 409         ENTRY;
 410
 411         name2qstr(&name, de->name, de->name_len);
 412
 413         se = ll_sai_entry_get(lli->lli_sai, lli->lli_sai->sai_sent,
 414                               SA_ENTRY_UNSTATED);
 415
 416 #ifdef DCACHE_LUSTRE_INVALID
 417         if (parent->d_flags & DCACHE_LUSTRE_INVALID) {
 418 #else
 419         if (d_unhashed(parent)) {
 420 #endif
 421                 CDEBUG(D_READA, "parent dentry@%p %.*s is "
 422                        "invalid, skip statahead\n",
 423                        parent, parent->d_name.len, parent->d_name.name);
 424                 GOTO(out, rc = -EINVAL);
 425         }
 426
 427         dentry = d_lookup(parent, &name);
 428         if (!dentry) {
 429                 struct dentry *dentry = d_alloc(parent, &name);
 430
 431                 rc = -ENOMEM;
 432                 if (dentry) {
 433                         rc = do_sa_lookup(dir, dentry);
 434                         if (rc)
 435                                 dput(dentry);
 436                 }
 437                 GOTO(out, rc);
 438         }
 439
 440         rc = do_sa_revalidate(dentry);
 441         if (rc)
 442                 dput(dentry);
 443         GOTO(out, rc);
 444 out:
 445         if (rc) {
 446                 CDEBUG(D_READA, "set sai entry %p index %d stat %d, rc %d\n",
 447                        se, se->se_index, se->se_stat, rc);
 448                 se->se_stat = rc;
 449                 wake_up(&lli->lli_sai->sai_thread.t_ctl_waitq);
 450         }
 451         lli->lli_sai->sai_sent++;
 452         return rc;
 453 }
 454
 455 static inline int sa_check_stop(struct ll_statahead_info *sai)
 456 {
 457         return !!(sai->sai_thread.t_flags & SVC_STOPPING);
 458 }
 459
 460 static inline int sa_not_full(struct ll_statahead_info *sai)
 461 {
 462         return sai->sai_sent - sai->sai_miss - sai->sai_hit < sai->sai_max;
 463 }
 464
 465 struct ll_sa_thread_args {
 466         struct dentry   *sta_parent;
 467         pid_t            sta_pid;
 468 };
 469
 470 static int ll_statahead_thread(void *arg)
 471 {
 472         struct ll_sa_thread_args *sta = arg;
 473         struct dentry            *parent = dget(sta->sta_parent);
 474         struct inode             *dir = parent->d_inode;
 475         struct ll_inode_info     *lli = ll_i2info(dir);
 476         struct ll_sb_info        *sbi = ll_i2sbi(dir);
 477         struct ll_statahead_info *sai = ll_sai_get(lli->lli_sai);
 478         struct ptlrpc_thread     *thread = &sai->sai_thread;
 479         struct l_wait_info        lwi = { 0 };
 480         unsigned long             index = 0;
 481         __u64                     offset = 0;
 482         int                       skip = 0;
 483         int                       rc = 0;
 484         char                      name[16] = "";
 485         ENTRY;
 486
 487         sbi->ll_sa_total++;
 488
 489         snprintf(name, 15, "ll_sa_%u", sta->sta_pid);
 490         cfs_daemonize(name);
 491         thread->t_flags = SVC_RUNNING;
 492         wake_up(&thread->t_ctl_waitq);
 493         CDEBUG(D_READA, "start doing statahead for %s\n", parent->d_name.name);
 494
 495         if (sai->sai_ls_all)
 496                 CDEBUG(D_READA, "do statahead for hidden files\n");
 497
 498         while (1) {
 499                 unsigned long npages = dir_pages(dir);
 500
 501                 /* hit ratio < 80% */
 502                 if ((sai->sai_hit < 4 * sai->sai_miss && sai->sai_hit > 7) ||
 503                      (sai->sai_consecutive_miss > 8)) {
 504                         sbi->ll_sa_wrong++;
 505                         CDEBUG(D_READA, "statahead for dir %.*s hit ratio too "
 506                                "low: hit/miss %u/%u, sent/replied %u/%u, "
 507                                "cached %u\n",
 508                                parent->d_name.len, parent->d_name.name,
 509                                sai->sai_hit, sai->sai_miss, sai->sai_sent,
 510                                sai->sai_replied, sai->sai_cached);
 511                         break;
 512                 }
 513
 514                 /* reach the end of dir */
 515                 if (index == npages) {
 516                         CDEBUG(D_READA, "reach end, index/npages %lu/%lu\n",
 517                                index, npages);
 518                         break;
 519                 }
 520
 521                 l_wait_event(thread->t_ctl_waitq,
 522                              sa_check_stop(sai) || sa_not_full(sai),
 523                              &lwi);
 524
 525                 if (sa_check_stop(sai))
 526                         break;
 527
 528                 for (; index < npages; index++, offset = 0) {
 529                         char *kaddr, *limit;
 530                         ext2_dirent *de;
 531                         struct page *page;
 532
 533                         CDEBUG(D_EXT2,"read %lu of dir %lu/%u page %lu"
 534                                "/%lu size %llu\n",
 535                                CFS_PAGE_SIZE, dir->i_ino, dir->i_generation,
 536                                index, npages, dir->i_size);
 537
 538                         page = ll_get_dir_page(dir, index);
 539                         npages = dir_pages(dir);
 540
 541                         if (IS_ERR(page)) {
 542                                 rc = PTR_ERR(page);
 543                                 CERROR("error reading dir %lu/%u page %lu: "
 544                                        "rc %d\n",
 545                                        dir->i_ino, dir->i_generation, index,
 546                                        rc);
 547                                 GOTO(out, rc);
 548                         }
 549
 550                         kaddr = page_address(page);
 551                         de = (ext2_dirent *)(kaddr + offset);
 552                         limit = kaddr + CFS_PAGE_SIZE - EXT2_DIR_REC_LEN(1);
 553                         for (; (char*)de <= limit && sa_not_full(sai);
 554                              de = ext2_next_entry(de)) {
 555                                 if (!de->inode)
 556                                         continue;
 557
 558                                 /* don't stat-ahead ".", ".." */
 559                                 if (skip < 2) {
 560                                         skip++;
 561                                         continue;
 562                                 }
 563
 564                                 /* don't stat-ahead for hidden files */
 565                                 if (de->name[0] == '.' && !sai->sai_ls_all)
 566                                         continue;
 567
 568                                 /* don't stat-ahead for the first de */
 569                                 if (skip < 3) {
 570                                         skip++;
 571                                         continue;
 572                                 }
 573
 574                                 rc = ll_statahead_one(parent, de);
 575                                 if (rc < 0) {
 576                                         ext2_put_page(page);
 577                                         GOTO(out, rc);
 578                                 }
 579                         }
 580                         offset = (char *)de - kaddr;
 581                         ext2_put_page(page);
 582
 583                         if ((char *)de <= limit)
 584                                 /* !sa_not_full() */
 585                                 break;
 586                 }
 587         }
 588         EXIT;
 589 out:
 590         thread->t_flags = SVC_STOPPED;
 591         wake_up(&thread->t_ctl_waitq);
 592         lli->lli_opendir_pid = 0; /* avoid statahead again */
 593         ll_sai_put(sai);
 594         dput(parent);
 595         CDEBUG(D_READA, "stopped statahead thread, pid %d for %s\n",
 596                current->pid, parent->d_name.name);
 597         return 0;
 598 }
 599
 600 /* called in ll_file_release */
 601 void ll_stop_statahead(struct inode *inode)
 602 {
 603         struct ll_inode_info *lli = ll_i2info(inode);
 604         struct ptlrpc_thread *thread;
 605
 606         /* don't check pid here. upon fork, if parent closedir before child,
 607          * child will not have chance to stop this thread. */
 608         lli->lli_opendir_pid = 0;
 609
 610         spin_lock(&lli->lli_lock);
 611         if (lli->lli_sai) {
 612                 ll_sai_get(lli->lli_sai);
 613                 spin_unlock(&lli->lli_lock);
 614
 615                 CDEBUG(D_READA, "stopping statahead thread, pid %d\n",
 616                        current->pid);
 617                 thread = &lli->lli_sai->sai_thread;
 618                 thread->t_flags = SVC_STOPPING;
 619                 wake_up(&thread->t_ctl_waitq);
 620                 wait_event(thread->t_ctl_waitq, thread->t_flags & SVC_STOPPED);
 621                 ll_sai_put(lli->lli_sai);
 622
 623                 return;
 624         }
 625         spin_unlock(&lli->lli_lock);
 626 }
 627
 628 enum {
 629         LS_NONE_FIRST_DE = 0,   /* not first dirent, or is "." */
 630         LS_FIRST_DE,            /* the first non-hidden dirent */
 631         LS_FIRST_DOT_DE         /* the first hidden dirent, that is ".xxx" */
 632 };
 633
 634 static int is_first_dirent(struct inode *dir, struct dentry *dentry)
 635 {
 636         struct qstr   *d_name = &dentry->d_name;
 637         unsigned long  npages = dir_pages(dir);
 638         struct page   *page;
 639         ext2_dirent   *de;
 640         unsigned long  index;
 641         __u64          offset = 0;
 642         char          *kaddr, *limit;
 643         int            dot_de = 1; /* dirent is dotfile till now */
 644         int            rc = LS_NONE_FIRST_DE;
 645         ENTRY;
 646
 647         page = ll_get_dir_page(dir, 0);
 648         if (IS_ERR(page)) {
 649                 CERROR("error reading dir %lu/%u page 0: rc %ld\n",
 650                        dir->i_ino, dir->i_generation, PTR_ERR(page));
 651                 RETURN(LS_NONE_FIRST_DE);
 652         }
 653
 654         kaddr = page_address(page);
 655         de = (ext2_dirent *)kaddr;
 656         if (!(de->name_len == 1 && strncmp(de->name, ".", 1) == 0))
 657                 CWARN("Maybe got bad on-disk dir:%lu\n", dir->i_ino);
 658         de = ext2_next_entry(de); /* skip ".", or ingore bad entry */
 659         if (!(de->name_len == 2 && strncmp(de->name, "..", 2) == 0))
 660                 CWARN("Maybe got bad on-disk dir:%lu\n", dir->i_ino);
 661         de = ext2_next_entry(de); /* skip "..", or ingore bad entry */
 662
 663         offset = (char *)de - kaddr;
 664
 665         for (index = 0; index < npages; offset = 0) {
 666                 de = (ext2_dirent *)(kaddr + offset);
 667                 limit = kaddr + CFS_PAGE_SIZE - EXT2_DIR_REC_LEN(1);
 668                 for (; (char*)de <= limit; de = ext2_next_entry(de)) {
 669                         if (!de->inode)
 670                                 continue;
 671
 672                         if (de->name[0] != '.')
 673                                 dot_de = 0;
 674
 675                         if (dot_de && d_name->name[0] != '.') {
 676                                 CDEBUG(D_READA, "%.*s skip hidden file %.*s\n",
 677                                        d_name->len, d_name->name,
 678                                        de->name_len, de->name);
 679                                 continue;
 680                         }
 681
 682                         if (d_name->len == de->name_len &&
 683                             !strncmp(d_name->name, de->name, d_name->len))
 684                                 rc = LS_FIRST_DE + dot_de;
 685                         else
 686                                 rc = LS_NONE_FIRST_DE;
 687                         GOTO(out, rc);
 688                 }
 689
 690                 if (++index >= npages)
 691                         break;
 692
 693                 ext2_put_page(page);
 694
 695                 page = ll_get_dir_page(dir, index);
 696                 if (IS_ERR(page)) {
 697                         CERROR("error reading dir %lu/%u page %lu: rc %ld\n",
 698                                dir->i_ino, dir->i_generation, index,
 699                                PTR_ERR(page));
 700                         RETURN(LS_NONE_FIRST_DE);
 701                 }
 702                 kaddr = page_address(page);
 703         }
 704         CERROR("%.*s not found in dir %.*s!\n", d_name->len, d_name->name,
 705                dentry->d_parent->d_name.len, dentry->d_parent->d_name.name);
 706         EXIT;
 707 out:
 708         ext2_put_page(page);
 709         return rc;
 710 }
 711
 712 /* start stat-ahead thread if this is the first dir entry, otherwise if a thread
 713  * is started already, wait until thread is ahead of me.
 714  * Return value:
 715  *    0 -- miss,
 716  *    1 -- hit,
 717  *    -EEXIST -- stat ahead thread started, and this is the first try.
 718  *    other negative value -- error.
 719  */
 720 int ll_statahead_enter(struct inode *dir, struct dentry **dentryp, int lookup)
 721 {
 722         struct ll_sb_info        *sbi = ll_i2sbi(dir);
 723         struct ll_inode_info     *lli = ll_i2info(dir);
 724         struct ll_statahead_info *sai;
 725         struct ll_sa_thread_args  sta;
 726         int                       rc;
 727         ENTRY;
 728
 729         if (sbi->ll_sa_max == 0)
 730                 RETURN(-ENOTSUPP);
 731
 732         /* not the same process, don't statahead */
 733         if (lli->lli_opendir_pid != current->pid)
 734                 RETURN(-EBADF);
 735
 736         spin_lock(&lli->lli_lock);
 737         if (lli->lli_sai) {
 738                 sai = ll_sai_get(lli->lli_sai);
 739                 spin_unlock(&lli->lli_lock);
 740
 741                 if (ll_sai_entry_stated(sai)) {
 742                         sbi->ll_sa_cached++;
 743                 } else {
 744                         struct l_wait_info lwi = { 0 };
 745
 746                         sbi->ll_sa_blocked++;
 747                         /* thread started already, avoid double-stat */
 748                         l_wait_event(sai->sai_thread.t_ctl_waitq,
 749                                      ll_sai_entry_stated(sai) ||
 750                                      sai->sai_thread.t_flags & SVC_STOPPED,
 751                                      &lwi);
 752                 }
 753
 754                 ll_sai_put(sai);
 755
 756                 if (lookup) {
 757                         struct dentry *result;
 758
 759                         result = d_lookup((*dentryp)->d_parent,
 760                                           &(*dentryp)->d_name);
 761                         if (result) {
 762                                 LASSERT(result != *dentryp);
 763                                 dput(*dentryp);
 764                                 *dentryp = result;
 765                         }
 766                         RETURN(result != NULL);
 767                 }
 768                 /* do nothing for revalidate */
 769                 RETURN(0);
 770         }
 771         spin_unlock(&lli->lli_lock);
 772
 773         rc = is_first_dirent(dir, *dentryp);
 774         if (!rc) {
 775                 /* optimization: don't statahead for this pid any longer */
 776                 spin_lock(&lli->lli_lock);
 777                 if (lli->lli_sai == NULL)
 778                         lli->lli_opendir_pid = 0;
 779                 spin_unlock(&lli->lli_lock);
 780                 RETURN(-EBADF);
 781         }
 782
 783         spin_lock(&lli->lli_lock);
 784         if (lli->lli_sai == NULL) {
 785                 lli->lli_sai = ll_sai_alloc();
 786                 if (lli->lli_sai == NULL) {
 787                         spin_unlock(&lli->lli_lock);
 788                         RETURN(-ENOMEM);
 789                 }
 790         } else {
 791                 /* sai is already there */
 792                 spin_unlock(&lli->lli_lock);
 793                 RETURN(-EBUSY);
 794         }
 795         spin_unlock(&lli->lli_lock);
 796
 797         sai = lli->lli_sai;
 798         sai->sai_inode = igrab(dir);
 799         sai->sai_ls_all = (rc == LS_FIRST_DOT_DE);
 800
 801         sta.sta_parent = (*dentryp)->d_parent;
 802         sta.sta_pid    = current->pid;
 803         rc = kernel_thread(ll_statahead_thread, &sta, 0);
 804         if (rc < 0) {
 805                 CERROR("can't start ll_sa thread, rc: %d\n", rc);
 806                 ll_sai_put(sai);
 807                 RETURN(rc);
 808         }
 809
 810         wait_event(sai->sai_thread.t_ctl_waitq,
 811                    sai->sai_thread.t_flags & (SVC_RUNNING | SVC_STOPPED));
 812         ll_sai_put(sai);
 813
 814         /* we don't stat-ahead for the first dirent since we are already in
 815          * lookup, and -EEXIST also indicates that this is the first dirent.
 816          */
 817         RETURN(-EEXIST);
 818 }
 819
 820 /* update hit/miss count */
 821 void ll_statahead_exit(struct dentry *dentry, int result)
 822 {
 823         struct ll_inode_info *lli = ll_i2info(dentry->d_parent->d_inode);
 824         struct ll_sb_info    *sbi = ll_i2sbi(dentry->d_parent->d_inode);
 825
 826         if (lli->lli_opendir_pid != current->pid)
 827                 return;
 828
 829         spin_lock(&lli->lli_lock);
 830         if (lli->lli_sai) {
 831                 struct ll_statahead_info *sai = lli->lli_sai;
 832
 833                 ll_sai_entry_put(sai);
 834                 if (result == 1) {
 835                         sai->sai_hit++;
 836                         sai->sai_consecutive_miss = 0;
 837                         sai->sai_max = min(2 * sai->sai_max, sbi->ll_sa_max);
 838                         CDEBUG(D_READA, "statahead %.*s hit(hit/miss %u/%u)\n",
 839                                dentry->d_name.len, dentry->d_name.name,
 840                                sai->sai_hit, sai->sai_miss);
 841                 } else {
 842                         sai->sai_miss++;
 843                         sai->sai_consecutive_miss++;
 844                         /* upon miss, it's always because some dentry is added
 845                          * by statahead thread, and at the mean time `ls`
 846                          * processs finds this dentry, but the d_op for this
 847                          * dentry is NULL, then revalidate is not done, and
 848                          * ll_statahead_exit() not called for this dentry,
 849                          * so statahead thread should be behind of `ls` process,
 850                          * put one entry to go ahead.
 851                          */
 852                         CDEBUG(D_READA, "statahead %.*s miss(hit/miss %u/%u)\n",
 853                                dentry->d_name.len, dentry->d_name.name,
 854                                sai->sai_hit, sai->sai_miss);
 855                         ll_sai_entry_put(sai);
 856                 }
 857                 wake_up(&sai->sai_thread.t_ctl_waitq);
 858         }
 859         spin_unlock(&lli->lli_lock);
 860 }