lustre/llite/rw.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.gnu.org/licenses/gpl-2.0.html
  19  *
  20  * GPL HEADER END
  21  */
  22 /*
  23  * Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
  24  * Use is subject to license terms.
  25  *
  26  * Copyright (c) 2011, 2017, Intel Corporation.
  27  */
  28 /*
  29  * This file is part of Lustre, http://www.lustre.org/
  30  * Lustre is a trademark of Sun Microsystems, Inc.
  31  *
  32  * lustre/llite/rw.c
  33  *
  34  * Lustre Lite I/O page cache routines shared by different kernel revs
  35  */
  36
  37 #include <linux/kernel.h>
  38 #include <linux/mm.h>
  39 #include <linux/string.h>
  40 #include <linux/stat.h>
  41 #include <linux/errno.h>
  42 #include <linux/unistd.h>
  43 #include <linux/writeback.h>
  44 #include <asm/uaccess.h>
  45
  46 #include <linux/fs.h>
  47 #include <linux/file.h>
  48 #include <linux/stat.h>
  49 #include <asm/uaccess.h>
  50 #include <linux/mm.h>
  51 #include <linux/pagemap.h>
  52 /* current_is_kswapd() */
  53 #include <linux/swap.h>
  54 #include <linux/task_io_accounting_ops.h>
  55
  56 #define DEBUG_SUBSYSTEM S_LLITE
  57
  58 #include <obd_cksum.h>
  59 #include "llite_internal.h"
  60 #include <lustre_compat.h>
  61
  62 static void ll_ra_stats_inc_sbi(struct ll_sb_info *sbi, enum ra_stat which);
  63
  64 /**
  65  * Get readahead pages from the filesystem readahead pool of the client for a
  66  * thread.
  67  *
  68  * /param sbi superblock for filesystem readahead state ll_ra_info
  69  * /param ria per-thread readahead state
  70  * /param pages number of pages requested for readahead for the thread.
  71  *
  72  * WARNING: This algorithm is used to reduce contention on sbi->ll_lock.
  73  * It should work well if the ra_max_pages is much greater than the single
  74  * file's read-ahead window, and not too many threads contending for
  75  * these readahead pages.
  76  *
  77  * TODO: There may be a 'global sync problem' if many threads are trying
  78  * to get an ra budget that is larger than the remaining readahead pages
  79  * and reach here at exactly the same time. They will compute /a ret to
  80  * consume the remaining pages, but will fail at atomic_add_return() and
  81  * get a zero ra window, although there is still ra space remaining. - Jay */
  82
  83 static unsigned long ll_ra_count_get(struct ll_sb_info *sbi,
  84                                      struct ra_io_arg *ria,
  85                                      unsigned long pages,
  86                                      unsigned long pages_min)
  87 {
  88         struct ll_ra_info *ra = &sbi->ll_ra_info;
  89         long ret;
  90         ENTRY;
  91
  92         /* If read-ahead pages left are less than 1M, do not do read-ahead,
  93          * otherwise it will form small read RPC(< 1M), which hurt server
  94          * performance a lot. */
  95         ret = min(ra->ra_max_pages - atomic_read(&ra->ra_cur_pages),
  96                   pages);
  97         if (ret < 0 || ret < min_t(long, PTLRPC_MAX_BRW_PAGES, pages))
  98                 GOTO(out, ret = 0);
  99
 100         if (atomic_add_return(ret, &ra->ra_cur_pages) > ra->ra_max_pages) {
 101                 atomic_sub(ret, &ra->ra_cur_pages);
 102                 ret = 0;
 103         }
 104
 105 out:
 106         if (ret < pages_min) {
 107                 /* override ra limit for maximum performance */
 108                 atomic_add(pages_min - ret, &ra->ra_cur_pages);
 109                 ret = pages_min;
 110         }
 111         RETURN(ret);
 112 }
 113
 114 void ll_ra_count_put(struct ll_sb_info *sbi, unsigned long pages)
 115 {
 116         struct ll_ra_info *ra = &sbi->ll_ra_info;
 117         atomic_sub(pages, &ra->ra_cur_pages);
 118 }
 119
 120 static void ll_ra_stats_inc_sbi(struct ll_sb_info *sbi, enum ra_stat which)
 121 {
 122         LASSERTF(which < _NR_RA_STAT, "which: %u\n", which);
 123         lprocfs_counter_incr(sbi->ll_ra_stats, which);
 124 }
 125
 126 static inline bool ll_readahead_enabled(struct ll_sb_info *sbi)
 127 {
 128         return sbi->ll_ra_info.ra_max_pages_per_file > 0 &&
 129                 sbi->ll_ra_info.ra_max_pages > 0;
 130 }
 131
 132 void ll_ra_stats_inc(struct inode *inode, enum ra_stat which)
 133 {
 134         struct ll_sb_info *sbi = ll_i2sbi(inode);
 135         ll_ra_stats_inc_sbi(sbi, which);
 136 }
 137
 138 #define RAS_CDEBUG(ras) \
 139         CDEBUG(D_READA,                                                      \
 140                "lre %llu cr %lu cb %llu wsi %lu wp %lu nra %lu rpc %lu "     \
 141                "r %lu csr %lu so %llu sb %llu sl %llu lr %lu\n",             \
 142                ras->ras_last_read_end_bytes, ras->ras_consecutive_requests,  \
 143                ras->ras_consecutive_bytes, ras->ras_window_start_idx,        \
 144                ras->ras_window_pages, ras->ras_next_readahead_idx,           \
 145                ras->ras_rpc_pages, ras->ras_requests,                        \
 146                ras->ras_consecutive_stride_requests, ras->ras_stride_offset, \
 147                ras->ras_stride_bytes, ras->ras_stride_length,                \
 148                ras->ras_async_last_readpage_idx)
 149
 150 static bool pos_in_window(loff_t pos, loff_t point,
 151                           unsigned long before, unsigned long after)
 152 {
 153         loff_t start = point - before;
 154         loff_t end = point + after;
 155
 156         if (start > point)
 157                 start = 0;
 158         if (end < point)
 159                 end = ~0;
 160
 161         return start <= pos && pos <= end;
 162 }
 163
 164 enum ll_ra_page_hint {
 165         MAYNEED = 0, /* this page possibly accessed soon */
 166         WILLNEED /* this page is gurateed to be needed */
 167 };
 168
 169 /**
 170  * Initiates read-ahead of a page with given index.
 171  *
 172  * \retval +ve: page was already uptodate so it will be skipped
 173  *              from being added;
 174  * \retval -ve: page wasn't added to \a queue for error;
 175  * \retval   0: page was added into \a queue for read ahead.
 176  */
 177 static int ll_read_ahead_page(const struct lu_env *env, struct cl_io *io,
 178                               struct cl_page_list *queue, pgoff_t index,
 179                               enum ll_ra_page_hint hint)
 180 {
 181         struct cl_object *clob  = io->ci_obj;
 182         struct inode     *inode = vvp_object_inode(clob);
 183         struct page      *vmpage = NULL;
 184         struct cl_page   *page;
 185         struct vvp_page  *vpg;
 186         enum ra_stat      which = _NR_RA_STAT; /* keep gcc happy */
 187         int               rc    = 0;
 188         const char       *msg   = NULL;
 189
 190         ENTRY;
 191
 192         switch (hint) {
 193         case MAYNEED:
 194                 vmpage = grab_cache_page_nowait(inode->i_mapping, index);
 195                 if (vmpage == NULL) {
 196                         which = RA_STAT_FAILED_GRAB_PAGE;
 197                         msg   = "g_c_p_n failed";
 198                         GOTO(out, rc = -EBUSY);
 199                 }
 200                 break;
 201         case WILLNEED:
 202                 vmpage = find_or_create_page(inode->i_mapping, index,
 203                                              GFP_NOFS);
 204                 if (vmpage == NULL)
 205                         GOTO(out, rc = -ENOMEM);
 206                 break;
 207         default:
 208                 /* should not come here */
 209                 GOTO(out, rc = -EINVAL);
 210         }
 211
 212         /* Check if vmpage was truncated or reclaimed */
 213         if (vmpage->mapping != inode->i_mapping) {
 214                 which = RA_STAT_WRONG_GRAB_PAGE;
 215                 msg   = "g_c_p_n returned invalid page";
 216                 GOTO(out, rc = -EBUSY);
 217         }
 218
 219         page = cl_page_find(env, clob, vmpage->index, vmpage, CPT_CACHEABLE);
 220         if (IS_ERR(page)) {
 221                 which = RA_STAT_FAILED_GRAB_PAGE;
 222                 msg   = "cl_page_find failed";
 223                 GOTO(out, rc = PTR_ERR(page));
 224         }
 225
 226         lu_ref_add(&page->cp_reference, "ra", current);
 227         cl_page_assume(env, io, page);
 228         vpg = cl2vvp_page(cl_object_page_slice(clob, page));
 229         if (!vpg->vpg_defer_uptodate && !PageUptodate(vmpage)) {
 230                 vpg->vpg_defer_uptodate = 1;
 231                 vpg->vpg_ra_used = 0;
 232                 cl_page_list_add(queue, page);
 233         } else {
 234                 /* skip completed pages */
 235                 cl_page_unassume(env, io, page);
 236                 /* This page is already uptodate, returning a positive number
 237                  * to tell the callers about this */
 238                 rc = 1;
 239         }
 240
 241         lu_ref_del(&page->cp_reference, "ra", current);
 242         cl_page_put(env, page);
 243
 244 out:
 245         if (vmpage != NULL) {
 246                 if (rc != 0)
 247                         unlock_page(vmpage);
 248                 put_page(vmpage);
 249         }
 250         if (msg != NULL && hint == MAYNEED) {
 251                 ll_ra_stats_inc(inode, which);
 252                 CDEBUG(D_READA, "%s\n", msg);
 253
 254         }
 255
 256         RETURN(rc);
 257 }
 258
 259 #define RIA_DEBUG(ria)                                                  \
 260         CDEBUG(D_READA, "rs %lu re %lu ro %llu rl %llu rb %llu\n",      \
 261                ria->ria_start_idx, ria->ria_end_idx, ria->ria_stoff,    \
 262                ria->ria_length, ria->ria_bytes)
 263
 264 static inline int stride_io_mode(struct ll_readahead_state *ras)
 265 {
 266         return ras->ras_consecutive_stride_requests > 1;
 267 }
 268
 269 /* The function calculates how many bytes will be read in
 270  * [off, off + length], in such stride IO area,
 271  * stride_offset = st_off, stride_lengh = st_len,
 272  * stride_bytes = st_bytes
 273  *
 274  *   |------------------|*****|------------------|*****|------------|*****|....
 275  * st_off
 276  *   |--- st_bytes     ---|
 277  *   |-----     st_len   -----|
 278  *
 279  *              How many bytes it should read in such pattern
 280  *              |-------------------------------------------------------------|
 281  *              off
 282  *              |<------                  length                      ------->|
 283  *
 284  *          =   |<----->|  +  |-------------------------------------| +   |---|
 285  *             start_left                 st_bytes * i                 end_left
 286  */
 287 static loff_t stride_byte_count(loff_t st_off, loff_t st_len, loff_t st_bytes,
 288                                 loff_t off, loff_t length)
 289 {
 290         u64 start = off > st_off ? off - st_off : 0;
 291         u64 end = off + length > st_off ? off + length - st_off : 0;
 292         u64 start_left;
 293         u64 end_left;
 294         u64 bytes_count;
 295
 296         if (st_len == 0 || length == 0 || end == 0)
 297                 return length;
 298
 299         start = div64_u64_rem(start, st_len, &start_left);
 300         if (start_left < st_bytes)
 301                 start_left = st_bytes - start_left;
 302         else
 303                 start_left = 0;
 304
 305         end = div64_u64_rem(end, st_len, &end_left);
 306         if (end_left > st_bytes)
 307                 end_left = st_bytes;
 308
 309         CDEBUG(D_READA, "start %llu, end %llu start_left %llu end_left %llu\n",
 310                start, end, start_left, end_left);
 311
 312         if (start == end)
 313                 bytes_count = end_left - (st_bytes - start_left);
 314         else
 315                 bytes_count = start_left +
 316                         st_bytes * (end - start - 1) + end_left;
 317
 318         CDEBUG(D_READA,
 319                "st_off %llu, st_len %llu st_bytes %llu off %llu length %llu bytescount %llu\n",
 320                st_off, st_len, st_bytes, off, length, bytes_count);
 321
 322         return bytes_count;
 323 }
 324
 325 static unsigned long ria_page_count(struct ra_io_arg *ria)
 326 {
 327         loff_t length_bytes = ria->ria_end_idx >= ria->ria_start_idx ?
 328                 (loff_t)(ria->ria_end_idx -
 329                          ria->ria_start_idx + 1) << PAGE_SHIFT : 0;
 330         loff_t bytes_count;
 331
 332         if (ria->ria_length > ria->ria_bytes && ria->ria_bytes &&
 333             (ria->ria_length & ~PAGE_MASK || ria->ria_bytes & ~PAGE_MASK ||
 334              ria->ria_stoff & ~PAGE_MASK)) {
 335                 /* Over-estimate un-aligned page stride read */
 336                 unsigned long pg_count = ((ria->ria_bytes +
 337                                            PAGE_SIZE - 1) >> PAGE_SHIFT) + 1;
 338                 pg_count *= length_bytes / ria->ria_length + 1;
 339
 340                 return pg_count;
 341         }
 342         bytes_count = stride_byte_count(ria->ria_stoff, ria->ria_length,
 343                                         ria->ria_bytes,
 344                                         (loff_t)ria->ria_start_idx<<PAGE_SHIFT,
 345                                         length_bytes);
 346         return (bytes_count + PAGE_SIZE - 1) >> PAGE_SHIFT;
 347 }
 348
 349 static pgoff_t ras_align(struct ll_readahead_state *ras, pgoff_t index)
 350 {
 351         unsigned opt_size = min(ras->ras_window_pages, ras->ras_rpc_pages);
 352
 353         if (opt_size == 0)
 354                 opt_size = 1;
 355         return index - (index % opt_size);
 356 }
 357
 358 /* Check whether the index is in the defined ra-window */
 359 static bool ras_inside_ra_window(pgoff_t idx, struct ra_io_arg *ria)
 360 {
 361         loff_t pos = (loff_t)idx << PAGE_SHIFT;
 362
 363         /* If ria_length == ria_bytes, it means non-stride I/O mode,
 364          * idx should always inside read-ahead window in this case
 365          * For stride I/O mode, just check whether the idx is inside
 366          * the ria_bytes.
 367          */
 368         if (ria->ria_length == 0 || ria->ria_length == ria->ria_bytes)
 369                 return true;
 370
 371         if (pos >= ria->ria_stoff) {
 372                 u64 offset;
 373
 374                 div64_u64_rem(pos - ria->ria_stoff, ria->ria_length, &offset);
 375
 376                 if (offset < ria->ria_bytes ||
 377                     (ria->ria_length - offset) < PAGE_SIZE)
 378                         return true;
 379         } else if (pos + PAGE_SIZE > ria->ria_stoff) {
 380                 return true;
 381         }
 382
 383         return false;
 384 }
 385
 386 static unsigned long
 387 ll_read_ahead_pages(const struct lu_env *env, struct cl_io *io,
 388                     struct cl_page_list *queue, struct ll_readahead_state *ras,
 389                     struct ra_io_arg *ria, pgoff_t *ra_end, pgoff_t skip_index)
 390 {
 391         struct cl_read_ahead ra = { 0 };
 392         /* busy page count is per stride */
 393         int rc = 0, count = 0, busy_page_count = 0;
 394         pgoff_t page_idx;
 395
 396         LASSERT(ria != NULL);
 397         RIA_DEBUG(ria);
 398
 399         for (page_idx = ria->ria_start_idx;
 400              page_idx <= ria->ria_end_idx && ria->ria_reserved > 0;
 401              page_idx++) {
 402                 if (skip_index && page_idx == skip_index)
 403                         continue;
 404                 if (ras_inside_ra_window(page_idx, ria)) {
 405                         if (ra.cra_end_idx == 0 || ra.cra_end_idx < page_idx) {
 406                                 pgoff_t end_idx;
 407
 408                                 /*
 409                                  * Do not shrink ria_end_idx at any case until
 410                                  * the minimum end of current read is covered.
 411                                  *
 412                                  * Do not extend read lock accross stripe if
 413                                  * lock contention detected.
 414                                  */
 415                                 if (ra.cra_contention &&
 416                                     page_idx > ria->ria_end_idx_min) {
 417                                         ria->ria_end_idx = *ra_end;
 418                                         break;
 419                                 }
 420
 421                                 cl_read_ahead_release(env, &ra);
 422
 423                                 rc = cl_io_read_ahead(env, io, page_idx, &ra);
 424                                 if (rc < 0)
 425                                         break;
 426
 427                                  /*
 428                                   * Only shrink ria_end_idx if the matched
 429                                   * LDLM lock doesn't cover more.
 430                                   */
 431                                 if (page_idx > ra.cra_end_idx) {
 432                                         ria->ria_end_idx = ra.cra_end_idx;
 433                                         break;
 434                                 }
 435
 436                                 CDEBUG(D_READA, "idx: %lu, ra: %lu, rpc: %lu\n",
 437                                        page_idx, ra.cra_end_idx,
 438                                        ra.cra_rpc_pages);
 439                                 LASSERTF(ra.cra_end_idx >= page_idx,
 440                                          "object: %p, indcies %lu / %lu\n",
 441                                          io->ci_obj, ra.cra_end_idx, page_idx);
 442                                 /* update read ahead RPC size.
 443                                  * NB: it's racy but doesn't matter */
 444                                 if (ras->ras_rpc_pages != ra.cra_rpc_pages &&
 445                                     ra.cra_rpc_pages > 0)
 446                                         ras->ras_rpc_pages = ra.cra_rpc_pages;
 447                                 if (!skip_index) {
 448                                         /* trim it to align with optimal RPC size */
 449                                         end_idx = ras_align(ras, ria->ria_end_idx + 1);
 450                                         if (end_idx > 0 && !ria->ria_eof)
 451                                                 ria->ria_end_idx = end_idx - 1;
 452                                 }
 453                                 if (ria->ria_end_idx < ria->ria_end_idx_min)
 454                                         ria->ria_end_idx = ria->ria_end_idx_min;
 455                         }
 456                         if (page_idx > ria->ria_end_idx)
 457                                 break;
 458
 459                         /* If the page is inside the read-ahead window */
 460                         rc = ll_read_ahead_page(env, io, queue, page_idx,
 461                                                 MAYNEED);
 462                         if (rc < 0 && rc != -EBUSY)
 463                                 break;
 464                         if (rc == -EBUSY) {
 465                                 busy_page_count++;
 466                                 CDEBUG(D_READA,
 467                                        "skip busy page: %lu\n", page_idx);
 468                                 /* For page unaligned readahead the first
 469                                  * last pages of each region can be read by
 470                                  * another reader on the same node, and so
 471                                  * may be busy. So only stop for > 2 busy
 472                                  * pages. */
 473                                 if (busy_page_count > 2)
 474                                         break;
 475                         }
 476
 477                         *ra_end = page_idx;
 478                         /* Only subtract from reserve & count the page if we
 479                          * really did readahead on that page. */
 480                         if (rc == 0) {
 481                                 ria->ria_reserved--;
 482                                 count++;
 483                         }
 484                 } else if (stride_io_mode(ras)) {
 485                         /* If it is not in the read-ahead window, and it is
 486                          * read-ahead mode, then check whether it should skip
 487                          * the stride gap.
 488                          */
 489                         loff_t pos = (loff_t)page_idx << PAGE_SHIFT;
 490                         u64 offset;
 491
 492                         div64_u64_rem(pos - ria->ria_stoff, ria->ria_length,
 493                                       &offset);
 494                         if (offset >= ria->ria_bytes) {
 495                                 pos += (ria->ria_length - offset);
 496                                 if ((pos >> PAGE_SHIFT) >= page_idx + 1)
 497                                         page_idx = (pos >> PAGE_SHIFT) - 1;
 498                                 busy_page_count = 0;
 499                                 CDEBUG(D_READA,
 500                                        "Stride: jump %llu pages to %lu\n",
 501                                        ria->ria_length - offset, page_idx);
 502                                 continue;
 503                         }
 504                 }
 505         }
 506
 507         cl_read_ahead_release(env, &ra);
 508
 509         return count;
 510 }
 511
 512 static void ll_readahead_work_free(struct ll_readahead_work *work)
 513 {
 514         fput(work->lrw_file);
 515         OBD_FREE_PTR(work);
 516 }
 517
 518 static void ll_readahead_handle_work(struct work_struct *wq);
 519 static void ll_readahead_work_add(struct inode *inode,
 520                                   struct ll_readahead_work *work)
 521 {
 522         INIT_WORK(&work->lrw_readahead_work, ll_readahead_handle_work);
 523         queue_work(ll_i2sbi(inode)->ll_ra_info.ll_readahead_wq,
 524                    &work->lrw_readahead_work);
 525 }
 526
 527 static int ll_readahead_file_kms(const struct lu_env *env,
 528                                 struct cl_io *io, __u64 *kms)
 529 {
 530         struct cl_object *clob;
 531         struct inode *inode;
 532         struct cl_attr *attr = vvp_env_thread_attr(env);
 533         int ret;
 534
 535         clob = io->ci_obj;
 536         inode = vvp_object_inode(clob);
 537
 538         cl_object_attr_lock(clob);
 539         ret = cl_object_attr_get(env, clob, attr);
 540         cl_object_attr_unlock(clob);
 541
 542         if (ret != 0)
 543                 RETURN(ret);
 544
 545         *kms = attr->cat_kms;
 546         return 0;
 547 }
 548
 549 static void ll_readahead_handle_work(struct work_struct *wq)
 550 {
 551         struct ll_readahead_work *work;
 552         struct lu_env *env;
 553         __u16 refcheck;
 554         struct ra_io_arg *ria;
 555         struct inode *inode;
 556         struct ll_file_data *fd;
 557         struct ll_readahead_state *ras;
 558         struct cl_io *io;
 559         struct cl_2queue *queue;
 560         pgoff_t ra_end_idx = 0;
 561         unsigned long pages, pages_min = 0;
 562         struct file *file;
 563         __u64 kms;
 564         int rc;
 565         pgoff_t eof_index;
 566         struct ll_sb_info *sbi;
 567
 568         work = container_of(wq, struct ll_readahead_work,
 569                             lrw_readahead_work);
 570         fd = work->lrw_file->private_data;
 571         ras = &fd->fd_ras;
 572         file = work->lrw_file;
 573         inode = file_inode(file);
 574         sbi = ll_i2sbi(inode);
 575
 576         env = cl_env_alloc(&refcheck, LCT_NOREF);
 577         if (IS_ERR(env))
 578                 GOTO(out_free_work, rc = PTR_ERR(env));
 579
 580         io = vvp_env_thread_io(env);
 581         ll_io_init(io, file, CIT_READ, NULL);
 582
 583         rc = ll_readahead_file_kms(env, io, &kms);
 584         if (rc != 0)
 585                 GOTO(out_put_env, rc);
 586
 587         if (kms == 0) {
 588                 ll_ra_stats_inc(inode, RA_STAT_ZERO_LEN);
 589                 GOTO(out_put_env, rc = 0);
 590         }
 591
 592         ria = &ll_env_info(env)->lti_ria;
 593         memset(ria, 0, sizeof(*ria));
 594
 595         ria->ria_start_idx = work->lrw_start_idx;
 596         /* Truncate RA window to end of file */
 597         eof_index = (pgoff_t)(kms - 1) >> PAGE_SHIFT;
 598         if (eof_index <= work->lrw_end_idx) {
 599                 work->lrw_end_idx = eof_index;
 600                 ria->ria_eof = true;
 601         }
 602         if (work->lrw_end_idx <= work->lrw_start_idx)
 603                 GOTO(out_put_env, rc = 0);
 604
 605         ria->ria_end_idx = work->lrw_end_idx;
 606         pages = ria->ria_end_idx - ria->ria_start_idx + 1;
 607         ria->ria_reserved = ll_ra_count_get(sbi, ria,
 608                                             ria_page_count(ria), pages_min);
 609
 610         CDEBUG(D_READA,
 611                "async reserved pages: %lu/%lu/%lu, ra_cur %d, ra_max %lu\n",
 612                ria->ria_reserved, pages, pages_min,
 613                atomic_read(&ll_i2sbi(inode)->ll_ra_info.ra_cur_pages),
 614                ll_i2sbi(inode)->ll_ra_info.ra_max_pages);
 615
 616         if (ria->ria_reserved < pages) {
 617                 ll_ra_stats_inc(inode, RA_STAT_MAX_IN_FLIGHT);
 618                 if (PAGES_TO_MiB(ria->ria_reserved) < 1) {
 619                         ll_ra_count_put(ll_i2sbi(inode), ria->ria_reserved);
 620                         GOTO(out_put_env, rc = 0);
 621                 }
 622         }
 623
 624         rc = cl_io_rw_init(env, io, CIT_READ, ria->ria_start_idx, pages);
 625         if (rc)
 626                 GOTO(out_put_env, rc);
 627
 628         /* overwrite jobid inited in vvp_io_init() */
 629         if (strncmp(ll_i2info(inode)->lli_jobid, work->lrw_jobid,
 630                     sizeof(work->lrw_jobid)))
 631                 memcpy(ll_i2info(inode)->lli_jobid, work->lrw_jobid,
 632                        sizeof(work->lrw_jobid));
 633
 634         vvp_env_io(env)->vui_fd = fd;
 635         io->ci_state = CIS_LOCKED;
 636         io->ci_async_readahead = true;
 637         rc = cl_io_start(env, io);
 638         if (rc)
 639                 GOTO(out_io_fini, rc);
 640
 641         queue = &io->ci_queue;
 642         cl_2queue_init(queue);
 643
 644         rc = ll_read_ahead_pages(env, io, &queue->c2_qin, ras, ria,
 645                                  &ra_end_idx, 0);
 646         if (ria->ria_reserved != 0)
 647                 ll_ra_count_put(ll_i2sbi(inode), ria->ria_reserved);
 648         if (queue->c2_qin.pl_nr > 0) {
 649                 int count = queue->c2_qin.pl_nr;
 650
 651                 rc = cl_io_submit_rw(env, io, CRT_READ, queue);
 652                 if (rc == 0)
 653                         task_io_account_read(PAGE_SIZE * count);
 654         }
 655         if (ria->ria_end_idx == ra_end_idx && ra_end_idx == (kms >> PAGE_SHIFT))
 656                 ll_ra_stats_inc(inode, RA_STAT_EOF);
 657
 658         if (ra_end_idx != ria->ria_end_idx)
 659                 ll_ra_stats_inc(inode, RA_STAT_FAILED_REACH_END);
 660
 661         /* TODO: discard all pages until page reinit route is implemented */
 662         cl_page_list_discard(env, io, &queue->c2_qin);
 663
 664         /* Unlock unsent read pages in case of error. */
 665         cl_page_list_disown(env, io, &queue->c2_qin);
 666
 667         cl_2queue_fini(env, queue);
 668 out_io_fini:
 669         cl_io_end(env, io);
 670         cl_io_fini(env, io);
 671 out_put_env:
 672         cl_env_put(env, &refcheck);
 673 out_free_work:
 674         if (ra_end_idx > 0)
 675                 ll_ra_stats_inc_sbi(ll_i2sbi(inode), RA_STAT_ASYNC);
 676         atomic_dec(&sbi->ll_ra_info.ra_async_inflight);
 677         ll_readahead_work_free(work);
 678 }
 679
 680 static int ll_readahead(const struct lu_env *env, struct cl_io *io,
 681                         struct cl_page_list *queue,
 682                         struct ll_readahead_state *ras, bool hit,
 683                         struct file *file, pgoff_t skip_index)
 684 {
 685         struct vvp_io *vio = vvp_env_io(env);
 686         struct ll_thread_info *lti = ll_env_info(env);
 687         unsigned long pages, pages_min = 0;
 688         pgoff_t ra_end_idx = 0, start_idx = 0, end_idx = 0;
 689         struct inode *inode;
 690         struct ra_io_arg *ria = &lti->lti_ria;
 691         struct cl_object *clob;
 692         int ret = 0;
 693         __u64 kms;
 694         ENTRY;
 695
 696         clob = io->ci_obj;
 697         inode = vvp_object_inode(clob);
 698
 699         memset(ria, 0, sizeof(*ria));
 700         ret = ll_readahead_file_kms(env, io, &kms);
 701         if (ret != 0)
 702                 RETURN(ret);
 703
 704         if (kms == 0) {
 705                 ll_ra_stats_inc(inode, RA_STAT_ZERO_LEN);
 706                 RETURN(0);
 707         }
 708
 709         spin_lock(&ras->ras_lock);
 710
 711         /**
 712          * Note: other thread might rollback the ras_next_readahead_idx,
 713          * if it can not get the full size of prepared pages, see the
 714          * end of this function. For stride read ahead, it needs to
 715          * make sure the offset is no less than ras_stride_offset,
 716          * so that stride read ahead can work correctly.
 717          */
 718         if (stride_io_mode(ras))
 719                 start_idx = max_t(pgoff_t, ras->ras_next_readahead_idx,
 720                                   ras->ras_stride_offset >> PAGE_SHIFT);
 721         else
 722                 start_idx = ras->ras_next_readahead_idx;
 723
 724         if (ras->ras_window_pages > 0)
 725                 end_idx = ras->ras_window_start_idx + ras->ras_window_pages - 1;
 726
 727         if (skip_index)
 728                 end_idx = start_idx + ras->ras_window_pages - 1;
 729
 730         /* Enlarge the RA window to encompass the full read */
 731         if (vio->vui_ra_valid &&
 732             end_idx < vio->vui_ra_start_idx + vio->vui_ra_pages - 1)
 733                 end_idx = vio->vui_ra_start_idx + vio->vui_ra_pages - 1;
 734
 735         if (end_idx != 0) {
 736                 pgoff_t eof_index;
 737
 738                 /* Truncate RA window to end of file */
 739                 eof_index = (pgoff_t)((kms - 1) >> PAGE_SHIFT);
 740                 if (eof_index <= end_idx) {
 741                         end_idx = eof_index;
 742                         ria->ria_eof = true;
 743                 }
 744         }
 745         ria->ria_start_idx = start_idx;
 746         ria->ria_end_idx = end_idx;
 747         /* If stride I/O mode is detected, get stride window*/
 748         if (stride_io_mode(ras)) {
 749                 ria->ria_stoff = ras->ras_stride_offset;
 750                 ria->ria_length = ras->ras_stride_length;
 751                 ria->ria_bytes = ras->ras_stride_bytes;
 752         }
 753         spin_unlock(&ras->ras_lock);
 754
 755         if (end_idx == 0) {
 756                 ll_ra_stats_inc(inode, RA_STAT_ZERO_WINDOW);
 757                 RETURN(0);
 758         }
 759         pages = ria_page_count(ria);
 760         if (pages == 0) {
 761                 ll_ra_stats_inc(inode, RA_STAT_ZERO_WINDOW);
 762                 RETURN(0);
 763         }
 764
 765         RAS_CDEBUG(ras);
 766         CDEBUG(D_READA, DFID": ria: %lu/%lu, bead: %lu/%lu, hit: %d\n",
 767                PFID(lu_object_fid(&clob->co_lu)),
 768                ria->ria_start_idx, ria->ria_end_idx,
 769                vio->vui_ra_valid ? vio->vui_ra_start_idx : 0,
 770                vio->vui_ra_valid ? vio->vui_ra_pages : 0,
 771                hit);
 772
 773         /* at least to extend the readahead window to cover current read */
 774         if (!hit && vio->vui_ra_valid &&
 775             vio->vui_ra_start_idx + vio->vui_ra_pages > ria->ria_start_idx) {
 776                 ria->ria_end_idx_min =
 777                         vio->vui_ra_start_idx + vio->vui_ra_pages - 1;
 778                 pages_min = vio->vui_ra_start_idx + vio->vui_ra_pages -
 779                                 ria->ria_start_idx;
 780                  /**
 781                   * For performance reason, exceeding @ra_max_pages
 782                   * are allowed, but this should be limited with RPC
 783                   * size in case a large block size read issued. Trim
 784                   * to RPC boundary.
 785                   */
 786                 pages_min = min(pages_min, ras->ras_rpc_pages -
 787                                 (ria->ria_start_idx % ras->ras_rpc_pages));
 788         }
 789
 790         /* don't over reserved for mmap range read */
 791         if (skip_index)
 792                 pages_min = 0;
 793
 794         ria->ria_reserved = ll_ra_count_get(ll_i2sbi(inode), ria, pages,
 795                                             pages_min);
 796         if (ria->ria_reserved < pages)
 797                 ll_ra_stats_inc(inode, RA_STAT_MAX_IN_FLIGHT);
 798
 799         CDEBUG(D_READA, "reserved pages: %lu/%lu/%lu, ra_cur %d, ra_max %lu\n",
 800                ria->ria_reserved, pages, pages_min,
 801                atomic_read(&ll_i2sbi(inode)->ll_ra_info.ra_cur_pages),
 802                ll_i2sbi(inode)->ll_ra_info.ra_max_pages);
 803
 804         ret = ll_read_ahead_pages(env, io, queue, ras, ria, &ra_end_idx,
 805                                   skip_index);
 806         if (ria->ria_reserved != 0)
 807                 ll_ra_count_put(ll_i2sbi(inode), ria->ria_reserved);
 808
 809         if (ra_end_idx == end_idx && ra_end_idx == (kms >> PAGE_SHIFT))
 810                 ll_ra_stats_inc(inode, RA_STAT_EOF);
 811
 812         CDEBUG(D_READA,
 813                "ra_end_idx = %lu end_idx = %lu stride end = %lu pages = %d\n",
 814                ra_end_idx, end_idx, ria->ria_end_idx, ret);
 815
 816         if (ra_end_idx != end_idx)
 817                 ll_ra_stats_inc(inode, RA_STAT_FAILED_REACH_END);
 818         if (ra_end_idx > 0) {
 819                 /* update the ras so that the next read-ahead tries from
 820                  * where we left off. */
 821                 spin_lock(&ras->ras_lock);
 822                 ras->ras_next_readahead_idx = ra_end_idx + 1;
 823                 spin_unlock(&ras->ras_lock);
 824                 RAS_CDEBUG(ras);
 825         }
 826
 827         RETURN(ret);
 828 }
 829
 830 static int ll_readpages(const struct lu_env *env, struct cl_io *io,
 831                         struct cl_page_list *queue,
 832                         pgoff_t start, pgoff_t end)
 833 {
 834         int ret = 0;
 835         __u64 kms;
 836         pgoff_t page_idx;
 837         int count = 0;
 838
 839         ENTRY;
 840
 841         ret = ll_readahead_file_kms(env, io, &kms);
 842         if (ret != 0)
 843                 RETURN(ret);
 844
 845         if (kms == 0)
 846                 RETURN(0);
 847
 848         if (end != 0) {
 849                 unsigned long end_index;
 850
 851                 end_index = (unsigned long)((kms - 1) >> PAGE_SHIFT);
 852                 if (end_index <= end)
 853                         end = end_index;
 854         }
 855
 856         for (page_idx = start; page_idx <= end; page_idx++) {
 857                 ret= ll_read_ahead_page(env, io, queue, page_idx,
 858                                         WILLNEED);
 859                 if (ret < 0)
 860                         break;
 861                 else if (ret == 0) /* ret 1 is already uptodate */
 862                         count++;
 863         }
 864
 865         RETURN(count > 0 ? count : ret);
 866 }
 867
 868 static void ras_set_start(struct ll_readahead_state *ras, pgoff_t index)
 869 {
 870         ras->ras_window_start_idx = ras_align(ras, index);
 871 }
 872
 873 /* called with the ras_lock held or from places where it doesn't matter */
 874 static void ras_reset(struct ll_readahead_state *ras, pgoff_t index)
 875 {
 876         ras->ras_consecutive_requests = 0;
 877         ras->ras_consecutive_bytes = 0;
 878         ras->ras_window_pages = 0;
 879         ras_set_start(ras, index);
 880         ras->ras_next_readahead_idx = max(ras->ras_window_start_idx, index + 1);
 881
 882         RAS_CDEBUG(ras);
 883 }
 884
 885 /* called with the ras_lock held or from places where it doesn't matter */
 886 static void ras_stride_reset(struct ll_readahead_state *ras)
 887 {
 888         ras->ras_consecutive_stride_requests = 0;
 889         ras->ras_stride_length = 0;
 890         ras->ras_stride_bytes = 0;
 891         RAS_CDEBUG(ras);
 892 }
 893
 894 void ll_readahead_init(struct inode *inode, struct ll_readahead_state *ras)
 895 {
 896         spin_lock_init(&ras->ras_lock);
 897         ras->ras_rpc_pages = PTLRPC_MAX_BRW_PAGES;
 898         ras_reset(ras, 0);
 899         ras->ras_last_read_end_bytes = 0;
 900         ras->ras_requests = 0;
 901         ras->ras_range_min_start_idx = 0;
 902         ras->ras_range_max_end_idx = 0;
 903         ras->ras_range_requests = 0;
 904         ras->ras_last_range_pages = 0;
 905 }
 906
 907 /*
 908  * Check whether the read request is in the stride window.
 909  * If it is in the stride window, return true, otherwise return false.
 910  */
 911 static bool read_in_stride_window(struct ll_readahead_state *ras,
 912                                   loff_t pos, loff_t count)
 913 {
 914         loff_t stride_gap;
 915
 916         if (ras->ras_stride_length == 0 || ras->ras_stride_bytes == 0 ||
 917             ras->ras_stride_bytes == ras->ras_stride_length)
 918                 return false;
 919
 920         stride_gap = pos - ras->ras_last_read_end_bytes - 1;
 921
 922         /* If it is contiguous read */
 923         if (stride_gap == 0)
 924                 return ras->ras_consecutive_bytes + count <=
 925                         ras->ras_stride_bytes;
 926
 927         /* Otherwise check the stride by itself */
 928         return (ras->ras_stride_length - ras->ras_stride_bytes) == stride_gap &&
 929                 ras->ras_consecutive_bytes == ras->ras_stride_bytes &&
 930                 count <= ras->ras_stride_bytes;
 931 }
 932
 933 static void ras_init_stride_detector(struct ll_readahead_state *ras,
 934                                      loff_t pos, loff_t count)
 935 {
 936         loff_t stride_gap = pos - ras->ras_last_read_end_bytes - 1;
 937
 938         LASSERT(ras->ras_consecutive_stride_requests == 0);
 939
 940         if (pos <= ras->ras_last_read_end_bytes) {
 941                 /*Reset stride window for forward read*/
 942                 ras_stride_reset(ras);
 943                 return;
 944         }
 945
 946         ras->ras_stride_bytes = ras->ras_consecutive_bytes;
 947         ras->ras_stride_length = stride_gap + ras->ras_consecutive_bytes;
 948         ras->ras_consecutive_stride_requests++;
 949         ras->ras_stride_offset = pos;
 950
 951         RAS_CDEBUG(ras);
 952 }
 953
 954 static unsigned long
 955 stride_page_count(struct ll_readahead_state *ras, loff_t len)
 956 {
 957         loff_t bytes_count =
 958                 stride_byte_count(ras->ras_stride_offset,
 959                                   ras->ras_stride_length, ras->ras_stride_bytes,
 960                                   ras->ras_window_start_idx << PAGE_SHIFT, len);
 961
 962         return (bytes_count + PAGE_SIZE - 1) >> PAGE_SHIFT;
 963 }
 964
 965 /* Stride Read-ahead window will be increased inc_len according to
 966  * stride I/O pattern */
 967 static void ras_stride_increase_window(struct ll_readahead_state *ras,
 968                                        struct ll_ra_info *ra, loff_t inc_bytes)
 969 {
 970         loff_t window_bytes, stride_bytes;
 971         u64 left_bytes;
 972         u64 step;
 973         loff_t end;
 974
 975         /* temporarily store in page units to reduce LASSERT() cost below */
 976         end = ras->ras_window_start_idx + ras->ras_window_pages;
 977
 978         LASSERT(ras->ras_stride_length > 0);
 979         LASSERTF(end >= (ras->ras_stride_offset >> PAGE_SHIFT),
 980                  "window_start_idx %lu, window_pages %lu stride_offset %llu\n",
 981                  ras->ras_window_start_idx, ras->ras_window_pages,
 982                  ras->ras_stride_offset);
 983
 984         end <<= PAGE_SHIFT;
 985         if (end <= ras->ras_stride_offset)
 986                 stride_bytes = 0;
 987         else
 988                 stride_bytes = end - ras->ras_stride_offset;
 989
 990         div64_u64_rem(stride_bytes, ras->ras_stride_length, &left_bytes);
 991         window_bytes = (ras->ras_window_pages << PAGE_SHIFT);
 992         if (left_bytes < ras->ras_stride_bytes) {
 993                 if (ras->ras_stride_bytes - left_bytes >= inc_bytes) {
 994                         window_bytes += inc_bytes;
 995                         goto out;
 996                 } else {
 997                         window_bytes += (ras->ras_stride_bytes - left_bytes);
 998                         inc_bytes -= (ras->ras_stride_bytes - left_bytes);
 999                 }
1000         } else {
1001                 window_bytes += (ras->ras_stride_length - left_bytes);
1002         }
1003
1004         LASSERT(ras->ras_stride_bytes != 0);
1005
1006         step = div64_u64_rem(inc_bytes, ras->ras_stride_bytes, &left_bytes);
1007
1008         window_bytes += step * ras->ras_stride_length + left_bytes;
1009         LASSERT(window_bytes > 0);
1010
1011 out:
1012         if (stride_page_count(ras, window_bytes) <=
1013             ra->ra_max_pages_per_file || ras->ras_window_pages == 0)
1014                 ras->ras_window_pages = (window_bytes >> PAGE_SHIFT);
1015
1016         LASSERT(ras->ras_window_pages > 0);
1017
1018         RAS_CDEBUG(ras);
1019 }
1020
1021 static void ras_increase_window(struct inode *inode,
1022                                 struct ll_readahead_state *ras,
1023                                 struct ll_ra_info *ra)
1024 {
1025         /* The stretch of ra-window should be aligned with max rpc_size
1026          * but current clio architecture does not support retrieve such
1027          * information from lower layer. FIXME later
1028          */
1029         if (stride_io_mode(ras)) {
1030                 ras_stride_increase_window(ras, ra,
1031                                       (loff_t)ras->ras_rpc_pages << PAGE_SHIFT);
1032         } else {
1033                 pgoff_t window_pages;
1034
1035                 window_pages = min(ras->ras_window_pages + ras->ras_rpc_pages,
1036                                    ra->ra_max_pages_per_file);
1037                 if (window_pages < ras->ras_rpc_pages)
1038                         ras->ras_window_pages = window_pages;
1039                 else
1040                         ras->ras_window_pages = ras_align(ras, window_pages);
1041         }
1042 }
1043
1044 /**
1045  * Seek within 8 pages are considered as sequential read for now.
1046  */
1047 static inline bool is_loose_seq_read(struct ll_readahead_state *ras, loff_t pos)
1048 {
1049         return pos_in_window(pos, ras->ras_last_read_end_bytes,
1050                              8UL << PAGE_SHIFT, 8UL << PAGE_SHIFT);
1051 }
1052
1053 static inline bool is_loose_mmap_read(struct ll_sb_info *sbi,
1054                                       struct ll_readahead_state *ras,
1055                                       unsigned long pos)
1056 {
1057         unsigned long range_pages = sbi->ll_ra_info.ra_range_pages;
1058
1059         return pos_in_window(pos, ras->ras_last_read_end_bytes,
1060                              range_pages << PAGE_SHIFT,
1061                              range_pages << PAGE_SHIFT);
1062 }
1063
1064 /**
1065  * We have observed slow mmap read performances for some
1066  * applications. The problem is if access pattern is neither
1067  * sequential nor stride, but could be still adjacent in a
1068  * small range and then seek a random position.
1069  *
1070  * So the pattern could be something like this:
1071  *
1072  * [1M data] [hole] [0.5M data] [hole] [0.7M data] [1M data]
1073  *
1074  *
1075  * Every time an application reads mmap data, it may not only
1076  * read a single 4KB page, but aslo a cluster of nearby pages in
1077  * a range(e.g. 1MB) of the first page after a cache miss.
1078  *
1079  * The readahead engine is modified to track the range size of
1080  * a cluster of mmap reads, so that after a seek and/or cache miss,
1081  * the range size is used to efficiently prefetch multiple pages
1082  * in a single RPC rather than many small RPCs.
1083  */
1084 static void ras_detect_cluster_range(struct ll_readahead_state *ras,
1085                                      struct ll_sb_info *sbi,
1086                                      unsigned long pos, unsigned long count)
1087 {
1088         pgoff_t last_pages, pages;
1089         pgoff_t end_idx = (pos + count - 1) >> PAGE_SHIFT;
1090
1091         last_pages = ras->ras_range_max_end_idx -
1092                         ras->ras_range_min_start_idx + 1;
1093         /* First time come here */
1094         if (!ras->ras_range_max_end_idx)
1095                 goto out;
1096
1097         /* Random or Stride read */
1098         if (!is_loose_mmap_read(sbi, ras, pos))
1099                 goto out;
1100
1101         ras->ras_range_requests++;
1102         if (ras->ras_range_max_end_idx < end_idx)
1103                 ras->ras_range_max_end_idx = end_idx;
1104
1105         if (ras->ras_range_min_start_idx > (pos >> PAGE_SHIFT))
1106                 ras->ras_range_min_start_idx = pos >> PAGE_SHIFT;
1107
1108         /* Out of range, consider it as random or stride */
1109         pages = ras->ras_range_max_end_idx -
1110                         ras->ras_range_min_start_idx + 1;
1111         if (pages <= sbi->ll_ra_info.ra_range_pages)
1112                 return;
1113 out:
1114         ras->ras_last_range_pages = last_pages;
1115         ras->ras_range_requests = 0;
1116         ras->ras_range_min_start_idx = pos >> PAGE_SHIFT;
1117         ras->ras_range_max_end_idx = end_idx;
1118 }
1119
1120 static void ras_detect_read_pattern(struct ll_readahead_state *ras,
1121                                     struct ll_sb_info *sbi,
1122                                     loff_t pos, size_t count, bool mmap)
1123 {
1124         bool stride_detect = false;
1125         pgoff_t index = pos >> PAGE_SHIFT;
1126
1127         /*
1128          * Reset the read-ahead window in two cases. First when the app seeks
1129          * or reads to some other part of the file. Secondly if we get a
1130          * read-ahead miss that we think we've previously issued. This can
1131          * be a symptom of there being so many read-ahead pages that the VM
1132          * is reclaiming it before we get to it.
1133          */
1134         if (!is_loose_seq_read(ras, pos)) {
1135                 /* Check whether it is in stride I/O mode */
1136                 if (!read_in_stride_window(ras, pos, count)) {
1137                         if (ras->ras_consecutive_stride_requests == 0)
1138                                 ras_init_stride_detector(ras, pos, count);
1139                         else
1140                                 ras_stride_reset(ras);
1141                         ras->ras_consecutive_bytes = 0;
1142                         ras_reset(ras, index);
1143                 } else {
1144                         ras->ras_consecutive_bytes = 0;
1145                         ras->ras_consecutive_requests = 0;
1146                         if (++ras->ras_consecutive_stride_requests > 1)
1147                                 stride_detect = true;
1148                         RAS_CDEBUG(ras);
1149                 }
1150                 ll_ra_stats_inc_sbi(sbi, RA_STAT_DISTANT_READPAGE);
1151         } else if (stride_io_mode(ras)) {
1152                 /*
1153                  * If this is contiguous read but in stride I/O mode
1154                  * currently, check whether stride step still is valid,
1155                  * if invalid, it will reset the stride ra window to
1156                  * be zero.
1157                  */
1158                 if (!read_in_stride_window(ras, pos, count)) {
1159                         ras_stride_reset(ras);
1160                         ras->ras_window_pages = 0;
1161                         ras->ras_next_readahead_idx = index;
1162                 }
1163         }
1164
1165         ras->ras_consecutive_bytes += count;
1166         if (mmap) {
1167                 pgoff_t idx = ras->ras_consecutive_bytes >> PAGE_SHIFT;
1168                 unsigned long ra_range_pages =
1169                                 max_t(unsigned long, RA_MIN_MMAP_RANGE_PAGES,
1170                                       sbi->ll_ra_info.ra_range_pages);
1171
1172                 if ((idx >= ra_range_pages &&
1173                      idx % ra_range_pages == 0) || stride_detect)
1174                         ras->ras_need_increase_window = true;
1175         } else if ((ras->ras_consecutive_requests > 1 || stride_detect)) {
1176                 ras->ras_need_increase_window = true;
1177         }
1178
1179         ras->ras_last_read_end_bytes = pos + count - 1;
1180 }
1181
1182 void ll_ras_enter(struct file *f, loff_t pos, size_t count)
1183 {
1184         struct ll_file_data *fd = f->private_data;
1185         struct ll_readahead_state *ras = &fd->fd_ras;
1186         struct inode *inode = file_inode(f);
1187         unsigned long index = pos >> PAGE_SHIFT;
1188         struct ll_sb_info *sbi = ll_i2sbi(inode);
1189
1190         spin_lock(&ras->ras_lock);
1191         ras->ras_requests++;
1192         ras->ras_consecutive_requests++;
1193         ras->ras_need_increase_window = false;
1194         ras->ras_no_miss_check = false;
1195         /*
1196          * On the second access to a file smaller than the tunable
1197          * ra_max_read_ahead_whole_pages trigger RA on all pages in the
1198          * file up to ra_max_pages_per_file.  This is simply a best effort
1199          * and only occurs once per open file. Normal RA behavior is reverted
1200          * to for subsequent IO.
1201          */
1202         if (ras->ras_requests >= 2) {
1203                 __u64 kms_pages;
1204                 struct ll_ra_info *ra = &sbi->ll_ra_info;
1205
1206                 kms_pages = (i_size_read(inode) + PAGE_SIZE - 1) >>
1207                             PAGE_SHIFT;
1208
1209                 CDEBUG(D_READA, "kmsp %llu mwp %lu mp %lu\n", kms_pages,
1210                        ra->ra_max_read_ahead_whole_pages,
1211                        ra->ra_max_pages_per_file);
1212
1213                 if (kms_pages &&
1214                     kms_pages <= ra->ra_max_read_ahead_whole_pages) {
1215                         ras->ras_window_start_idx = 0;
1216                         ras->ras_next_readahead_idx = index + 1;
1217                         ras->ras_window_pages = min(ra->ra_max_pages_per_file,
1218                                             ra->ra_max_read_ahead_whole_pages);
1219                         ras->ras_no_miss_check = true;
1220                         GOTO(out_unlock, 0);
1221                 }
1222         }
1223         ras_detect_read_pattern(ras, sbi, pos, count, false);
1224 out_unlock:
1225         spin_unlock(&ras->ras_lock);
1226 }
1227
1228 static bool index_in_stride_window(struct ll_readahead_state *ras,
1229                                    pgoff_t index)
1230 {
1231         loff_t pos = (loff_t)index << PAGE_SHIFT;
1232
1233         if (ras->ras_stride_length == 0 || ras->ras_stride_bytes == 0 ||
1234             ras->ras_stride_bytes == ras->ras_stride_length)
1235                 return false;
1236
1237         if (pos >= ras->ras_stride_offset) {
1238                 u64 offset;
1239
1240                 div64_u64_rem(pos - ras->ras_stride_offset,
1241                               ras->ras_stride_length, &offset);
1242                 if (offset < ras->ras_stride_bytes ||
1243                     ras->ras_stride_length - offset < PAGE_SIZE)
1244                         return true;
1245         } else if (ras->ras_stride_offset - pos < PAGE_SIZE) {
1246                 return true;
1247         }
1248
1249         return false;
1250 }
1251
1252 /*
1253  * ll_ras_enter() is used to detect read pattern according to pos and count.
1254  *
1255  * ras_update() is used to detect cache miss and
1256  * reset window or increase window accordingly
1257  */
1258 static void ras_update(struct ll_sb_info *sbi, struct inode *inode,
1259                        struct ll_readahead_state *ras, pgoff_t index,
1260                        enum ras_update_flags flags, struct cl_io *io)
1261 {
1262         struct ll_ra_info *ra = &sbi->ll_ra_info;
1263         bool hit = flags & LL_RAS_HIT;
1264
1265         ENTRY;
1266         spin_lock(&ras->ras_lock);
1267
1268         if (!hit)
1269                 CDEBUG(D_READA, DFID " pages at %lu miss.\n",
1270                        PFID(ll_inode2fid(inode)), index);
1271         ll_ra_stats_inc_sbi(sbi, hit ? RA_STAT_HIT : RA_STAT_MISS);
1272
1273         /*
1274          * The readahead window has been expanded to cover whole
1275          * file size, we don't care whether ra miss happen or not.
1276          * Because we will read whole file to page cache even if
1277          * some pages missed.
1278          */
1279         if (ras->ras_no_miss_check)
1280                 GOTO(out_unlock, 0);
1281
1282         if (io && io->ci_rand_read)
1283                 GOTO(out_unlock, 0);
1284
1285         if (io && io->ci_seq_read) {
1286                 if (!hit) {
1287                         /* to avoid many small read RPC here */
1288                         ras->ras_window_pages = sbi->ll_ra_info.ra_range_pages;
1289                         ll_ra_stats_inc_sbi(sbi, RA_STAT_MMAP_RANGE_READ);
1290                 }
1291                 goto skip;
1292         }
1293
1294         if (flags & LL_RAS_MMAP) {
1295                 unsigned long ra_pages;
1296
1297                 ras_detect_cluster_range(ras, sbi, index << PAGE_SHIFT,
1298                                          PAGE_SIZE);
1299                 ras_detect_read_pattern(ras, sbi, (loff_t)index << PAGE_SHIFT,
1300                                         PAGE_SIZE, true);
1301
1302                 /* we did not detect anything but we could prefetch */
1303                 if (!ras->ras_need_increase_window &&
1304                     ras->ras_window_pages <= sbi->ll_ra_info.ra_range_pages &&
1305                     ras->ras_range_requests >= 2) {
1306                         if (!hit) {
1307                                 ra_pages = max_t(unsigned long,
1308                                         RA_MIN_MMAP_RANGE_PAGES,
1309                                         ras->ras_last_range_pages);
1310                                 if (index < ra_pages / 2)
1311                                         index = 0;
1312                                 else
1313                                         index -= ra_pages / 2;
1314                                 ras->ras_window_pages = ra_pages;
1315                                 ll_ra_stats_inc_sbi(sbi,
1316                                         RA_STAT_MMAP_RANGE_READ);
1317                         } else {
1318                                 ras->ras_window_pages = 0;
1319                         }
1320                         goto skip;
1321                 }
1322         }
1323
1324         if (!hit && ras->ras_window_pages &&
1325             index < ras->ras_next_readahead_idx &&
1326             pos_in_window(index, ras->ras_window_start_idx, 0,
1327                           ras->ras_window_pages)) {
1328                 ll_ra_stats_inc_sbi(sbi, RA_STAT_MISS_IN_WINDOW);
1329                 ras->ras_need_increase_window = false;
1330
1331                 if (index_in_stride_window(ras, index) &&
1332                     stride_io_mode(ras)) {
1333                         /*
1334                          * if (index != ras->ras_last_readpage + 1)
1335                          *      ras->ras_consecutive_pages = 0;
1336                          */
1337                         ras_reset(ras, index);
1338
1339                         /*
1340                          * If stride-RA hit cache miss, the stride
1341                          * detector will not be reset to avoid the
1342                          * overhead of redetecting read-ahead mode,
1343                          * but on the condition that the stride window
1344                          * is still intersect with normal sequential
1345                          * read-ahead window.
1346                          */
1347                         if (ras->ras_window_start_idx < ras->ras_stride_offset)
1348                                 ras_stride_reset(ras);
1349                         RAS_CDEBUG(ras);
1350                 } else {
1351                         /*
1352                          * Reset both stride window and normal RA
1353                          * window.
1354                          */
1355                         ras_reset(ras, index);
1356                         /* ras->ras_consecutive_pages++; */
1357                         ras->ras_consecutive_bytes = 0;
1358                         ras_stride_reset(ras);
1359                         GOTO(out_unlock, 0);
1360                 }
1361         }
1362
1363 skip:
1364         ras_set_start(ras, index);
1365
1366         if (stride_io_mode(ras)) {
1367                 /* Since stride readahead is sentivite to the offset
1368                  * of read-ahead, so we use original offset here,
1369                  * instead of ras_window_start_idx, which is RPC aligned.
1370                  */
1371                 ras->ras_next_readahead_idx = max(index + 1,
1372                                                   ras->ras_next_readahead_idx);
1373                 ras->ras_window_start_idx =
1374                                 max_t(pgoff_t, ras->ras_window_start_idx,
1375                                       ras->ras_stride_offset >> PAGE_SHIFT);
1376         } else {
1377                 if (ras->ras_next_readahead_idx < ras->ras_window_start_idx)
1378                         ras->ras_next_readahead_idx = ras->ras_window_start_idx;
1379                 if (!hit)
1380                         ras->ras_next_readahead_idx = index + 1;
1381         }
1382
1383         if (ras->ras_need_increase_window) {
1384                 ras_increase_window(inode, ras, ra);
1385                 ras->ras_need_increase_window = false;
1386         }
1387
1388         EXIT;
1389 out_unlock:
1390         spin_unlock(&ras->ras_lock);
1391 }
1392
1393 int ll_writepage(struct page *vmpage, struct writeback_control *wbc)
1394 {
1395         struct inode           *inode = vmpage->mapping->host;
1396         struct ll_inode_info   *lli   = ll_i2info(inode);
1397         struct lu_env          *env;
1398         struct cl_io           *io;
1399         struct cl_page         *page;
1400         struct cl_object       *clob;
1401         bool redirtied = false;
1402         bool unlocked = false;
1403         int result;
1404         __u16 refcheck;
1405         ENTRY;
1406
1407         LASSERT(PageLocked(vmpage));
1408         LASSERT(!PageWriteback(vmpage));
1409
1410         LASSERT(ll_i2dtexp(inode) != NULL);
1411
1412         env = cl_env_get(&refcheck);
1413         if (IS_ERR(env))
1414                 GOTO(out, result = PTR_ERR(env));
1415
1416         clob  = ll_i2info(inode)->lli_clob;
1417         LASSERT(clob != NULL);
1418
1419         io = vvp_env_thread_io(env);
1420         io->ci_obj = clob;
1421         io->ci_ignore_layout = 1;
1422         result = cl_io_init(env, io, CIT_MISC, clob);
1423         if (result == 0) {
1424                 page = cl_page_find(env, clob, vmpage->index,
1425                                     vmpage, CPT_CACHEABLE);
1426                 if (!IS_ERR(page)) {
1427                         lu_ref_add(&page->cp_reference, "writepage",
1428                                    current);
1429                         cl_page_assume(env, io, page);
1430                         result = cl_page_flush(env, io, page);
1431                         if (result != 0) {
1432                                 /*
1433                                  * Re-dirty page on error so it retries write,
1434                                  * but not in case when IO has actually
1435                                  * occurred and completed with an error.
1436                                  */
1437                                 if (!PageError(vmpage)) {
1438                                         redirty_page_for_writepage(wbc, vmpage);
1439                                         result = 0;
1440                                         redirtied = true;
1441                                 }
1442                         }
1443                         cl_page_disown(env, io, page);
1444                         unlocked = true;
1445                         lu_ref_del(&page->cp_reference,
1446                                    "writepage", current);
1447                         cl_page_put(env, page);
1448                 } else {
1449                         result = PTR_ERR(page);
1450                 }
1451         }
1452         cl_io_fini(env, io);
1453
1454         if (redirtied && wbc->sync_mode == WB_SYNC_ALL) {
1455                 loff_t offset = cl_offset(clob, vmpage->index);
1456
1457                 /* Flush page failed because the extent is being written out.
1458                  * Wait for the write of extent to be finished to avoid
1459                  * breaking kernel which assumes ->writepage should mark
1460                  * PageWriteback or clean the page. */
1461                 result = cl_sync_file_range(inode, offset,
1462                                             offset + PAGE_SIZE - 1,
1463                                             CL_FSYNC_LOCAL, 1);
1464                 if (result > 0) {
1465                         /* actually we may have written more than one page.
1466                          * decreasing this page because the caller will count
1467                          * it. */
1468                         wbc->nr_to_write -= result - 1;
1469                         result = 0;
1470                 }
1471         }
1472
1473         cl_env_put(env, &refcheck);
1474         GOTO(out, result);
1475
1476 out:
1477         if (result < 0) {
1478                 if (!lli->lli_async_rc)
1479                         lli->lli_async_rc = result;
1480                 SetPageError(vmpage);
1481                 if (!unlocked)
1482                         unlock_page(vmpage);
1483         }
1484         return result;
1485 }
1486
1487 int ll_writepages(struct address_space *mapping, struct writeback_control *wbc)
1488 {
1489         struct inode *inode = mapping->host;
1490         loff_t start;
1491         loff_t end;
1492         enum cl_fsync_mode mode;
1493         int range_whole = 0;
1494         int result;
1495         ENTRY;
1496
1497         if (wbc->range_cyclic) {
1498                 start = (loff_t)mapping->writeback_index << PAGE_SHIFT;
1499                 end = OBD_OBJECT_EOF;
1500         } else {
1501                 start = wbc->range_start;
1502                 end = wbc->range_end;
1503                 if (end == LLONG_MAX) {
1504                         end = OBD_OBJECT_EOF;
1505                         range_whole = start == 0;
1506                 }
1507         }
1508
1509         mode = CL_FSYNC_NONE;
1510         if (wbc->sync_mode == WB_SYNC_ALL)
1511                 mode = CL_FSYNC_LOCAL;
1512
1513         if (ll_i2info(inode)->lli_clob == NULL)
1514                 RETURN(0);
1515
1516         /* for directio, it would call writepages() to evict cached pages
1517          * inside the IO context of write, which will cause deadlock at
1518          * layout_conf since it waits for active IOs to complete. */
1519         result = cl_sync_file_range(inode, start, end, mode, 1);
1520         if (result > 0) {
1521                 wbc->nr_to_write -= result;
1522                 result = 0;
1523          }
1524
1525         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0)) {
1526                 if (end == OBD_OBJECT_EOF)
1527                         mapping->writeback_index = 0;
1528                 else
1529                         mapping->writeback_index = (end >> PAGE_SHIFT) + 1;
1530         }
1531         RETURN(result);
1532 }
1533
1534 struct ll_cl_context *ll_cl_find(struct file *file)
1535 {
1536         struct ll_file_data *fd = file->private_data;
1537         struct ll_cl_context *lcc;
1538         struct ll_cl_context *found = NULL;
1539
1540         read_lock(&fd->fd_lock);
1541         list_for_each_entry(lcc, &fd->fd_lccs, lcc_list) {
1542                 if (lcc->lcc_cookie == current) {
1543                         found = lcc;
1544                         break;
1545                 }
1546         }
1547         read_unlock(&fd->fd_lock);
1548
1549         return found;
1550 }
1551
1552 void ll_cl_add(struct file *file, const struct lu_env *env, struct cl_io *io,
1553                enum lcc_type type)
1554 {
1555         struct ll_file_data *fd = file->private_data;
1556         struct ll_cl_context *lcc = &ll_env_info(env)->lti_io_ctx;
1557
1558         memset(lcc, 0, sizeof(*lcc));
1559         INIT_LIST_HEAD(&lcc->lcc_list);
1560         lcc->lcc_cookie = current;
1561         lcc->lcc_env = env;
1562         lcc->lcc_io = io;
1563         lcc->lcc_type = type;
1564
1565         write_lock(&fd->fd_lock);
1566         list_add(&lcc->lcc_list, &fd->fd_lccs);
1567         write_unlock(&fd->fd_lock);
1568 }
1569
1570 void ll_cl_remove(struct file *file, const struct lu_env *env)
1571 {
1572         struct ll_file_data *fd = file->private_data;
1573         struct ll_cl_context *lcc = &ll_env_info(env)->lti_io_ctx;
1574
1575         write_lock(&fd->fd_lock);
1576         list_del_init(&lcc->lcc_list);
1577         write_unlock(&fd->fd_lock);
1578 }
1579
1580 int ll_io_read_page(const struct lu_env *env, struct cl_io *io,
1581                            struct cl_page *page, struct file *file)
1582 {
1583         struct inode              *inode  = vvp_object_inode(page->cp_obj);
1584         struct ll_sb_info         *sbi    = ll_i2sbi(inode);
1585         struct ll_file_data       *fd     = NULL;
1586         struct ll_readahead_state *ras    = NULL;
1587         struct cl_2queue          *queue  = &io->ci_queue;
1588         struct cl_sync_io         *anchor = NULL;
1589         struct vvp_page           *vpg;
1590         int                        rc = 0, rc2 = 0;
1591         bool                       uptodate;
1592         pgoff_t io_start_index;
1593         pgoff_t io_end_index;
1594         ENTRY;
1595
1596         if (file) {
1597                 fd = file->private_data;
1598                 ras = &fd->fd_ras;
1599         }
1600
1601         vpg = cl2vvp_page(cl_object_page_slice(page->cp_obj, page));
1602         uptodate = vpg->vpg_defer_uptodate;
1603
1604         if (ll_readahead_enabled(sbi) && !vpg->vpg_ra_updated && ras) {
1605                 struct vvp_io *vio = vvp_env_io(env);
1606                 enum ras_update_flags flags = 0;
1607
1608                 if (uptodate)
1609                         flags |= LL_RAS_HIT;
1610                 if (!vio->vui_ra_valid)
1611                         flags |= LL_RAS_MMAP;
1612                 ras_update(sbi, inode, ras, vvp_index(vpg), flags, io);
1613         }
1614
1615         cl_2queue_init(queue);
1616         if (uptodate) {
1617                 vpg->vpg_ra_used = 1;
1618                 cl_page_export(env, page, 1);
1619                 cl_page_disown(env, io, page);
1620         } else {
1621                 anchor = &vvp_env_info(env)->vti_anchor;
1622                 cl_sync_io_init(anchor, 1);
1623                 page->cp_sync_io = anchor;
1624
1625                 cl_2queue_add(queue, page);
1626         }
1627
1628         io_start_index = cl_index(io->ci_obj, io->u.ci_rw.crw_pos);
1629         io_end_index = cl_index(io->ci_obj, io->u.ci_rw.crw_pos +
1630                                 io->u.ci_rw.crw_count - 1);
1631         if (ll_readahead_enabled(sbi) && ras && !io->ci_rand_read) {
1632                 pgoff_t skip_index = 0;
1633
1634                 if (ras->ras_next_readahead_idx < vvp_index(vpg))
1635                         skip_index = vvp_index(vpg);
1636                 rc2 = ll_readahead(env, io, &queue->c2_qin, ras,
1637                                    uptodate, file, skip_index);
1638                 CDEBUG(D_READA, DFID " %d pages read ahead at %lu\n",
1639                        PFID(ll_inode2fid(inode)), rc2, vvp_index(vpg));
1640         } else if (vvp_index(vpg) == io_start_index &&
1641                    io_end_index - io_start_index > 0) {
1642                 rc2 = ll_readpages(env, io, &queue->c2_qin, io_start_index + 1,
1643                                    io_end_index);
1644                 CDEBUG(D_READA, DFID " %d pages read at %lu\n",
1645                        PFID(ll_inode2fid(inode)), rc2, vvp_index(vpg));
1646         }
1647
1648         if (queue->c2_qin.pl_nr > 0) {
1649                 int count = queue->c2_qin.pl_nr;
1650                 rc = cl_io_submit_rw(env, io, CRT_READ, queue);
1651                 if (rc == 0)
1652                         task_io_account_read(PAGE_SIZE * count);
1653         }
1654
1655
1656         if (anchor != NULL && !cl_page_is_owned(page, io)) { /* have sent */
1657                 rc = cl_sync_io_wait(env, anchor, 0);
1658
1659                 cl_page_assume(env, io, page);
1660                 cl_page_list_del(env, &queue->c2_qout, page);
1661
1662                 if (!PageUptodate(cl_page_vmpage(page))) {
1663                         /* Failed to read a mirror, discard this page so that
1664                          * new page can be created with new mirror.
1665                          *
1666                          * TODO: this is not needed after page reinit
1667                          * route is implemented */
1668                         cl_page_discard(env, io, page);
1669                 }
1670                 cl_page_disown(env, io, page);
1671         }
1672
1673         /* TODO: discard all pages until page reinit route is implemented */
1674         cl_page_list_discard(env, io, &queue->c2_qin);
1675
1676         /* Unlock unsent read pages in case of error. */
1677         cl_page_list_disown(env, io, &queue->c2_qin);
1678
1679         cl_2queue_fini(env, queue);
1680
1681         RETURN(rc);
1682 }
1683
1684 /*
1685  * Possible return value:
1686  * 0 no async readahead triggered and fast read could not be used.
1687  * 1 no async readahead, but fast read could be used.
1688  * 2 async readahead triggered and fast read could be used too.
1689  * < 0 on error.
1690  */
1691 static int kickoff_async_readahead(struct file *file, unsigned long pages)
1692 {
1693         struct ll_readahead_work *lrw;
1694         struct inode *inode = file_inode(file);
1695         struct ll_sb_info *sbi = ll_i2sbi(inode);
1696         struct ll_file_data *fd = file->private_data;
1697         struct ll_readahead_state *ras = &fd->fd_ras;
1698         struct ll_ra_info *ra = &sbi->ll_ra_info;
1699         unsigned long throttle;
1700         pgoff_t start_idx = ras_align(ras, ras->ras_next_readahead_idx);
1701         pgoff_t end_idx = start_idx + pages - 1;
1702
1703         throttle = min(ra->ra_async_pages_per_file_threshold,
1704                        ra->ra_max_pages_per_file);
1705         /*
1706          * If this is strided i/o or the window is smaller than the
1707          * throttle limit, we do not do async readahead. Otherwise,
1708          * we do async readahead, allowing the user thread to do fast i/o.
1709          */
1710         if (stride_io_mode(ras) || !throttle ||
1711             ras->ras_window_pages < throttle ||
1712             atomic_read(&ra->ra_async_inflight) > ra->ra_async_max_active)
1713                 return 0;
1714
1715         if ((atomic_read(&ra->ra_cur_pages) + pages) > ra->ra_max_pages)
1716                 return 0;
1717
1718         if (ras->ras_async_last_readpage_idx == start_idx)
1719                 return 1;
1720
1721         /* ll_readahead_work_free() free it */
1722         OBD_ALLOC_PTR(lrw);
1723         if (lrw) {
1724                 atomic_inc(&sbi->ll_ra_info.ra_async_inflight);
1725                 lrw->lrw_file = get_file(file);
1726                 lrw->lrw_start_idx = start_idx;
1727                 lrw->lrw_end_idx = end_idx;
1728                 spin_lock(&ras->ras_lock);
1729                 ras->ras_next_readahead_idx = end_idx + 1;
1730                 ras->ras_async_last_readpage_idx = start_idx;
1731                 spin_unlock(&ras->ras_lock);
1732                 memcpy(lrw->lrw_jobid, ll_i2info(inode)->lli_jobid,
1733                        sizeof(lrw->lrw_jobid));
1734                 ll_readahead_work_add(inode, lrw);
1735         } else {
1736                 return -ENOMEM;
1737         }
1738
1739         return 2;
1740 }
1741
1742 /*
1743  * Check if we can issue a readahead RPC, if that is
1744  * the case, we can't do fast IO because we will need
1745  * a cl_io to issue the RPC.
1746  */
1747 static bool ll_use_fast_io(struct file *file,
1748                            struct ll_readahead_state *ras, pgoff_t index)
1749 {
1750         unsigned long fast_read_pages =
1751                 max(RA_REMAIN_WINDOW_MIN, ras->ras_rpc_pages);
1752         loff_t skip_pages;
1753         loff_t stride_bytes = ras->ras_stride_bytes;
1754
1755         if (stride_io_mode(ras) && stride_bytes) {
1756                 skip_pages = (ras->ras_stride_length +
1757                         ras->ras_stride_bytes - 1) / stride_bytes;
1758                 skip_pages *= fast_read_pages;
1759         } else {
1760                 skip_pages = fast_read_pages;
1761         }
1762
1763         if (ras->ras_window_start_idx + ras->ras_window_pages <
1764             ras->ras_next_readahead_idx + skip_pages ||
1765             kickoff_async_readahead(file, fast_read_pages) > 0)
1766                 return true;
1767
1768         return false;
1769 }
1770
1771 int ll_readpage(struct file *file, struct page *vmpage)
1772 {
1773         struct inode *inode = file_inode(file);
1774         struct cl_object *clob = ll_i2info(inode)->lli_clob;
1775         struct ll_cl_context *lcc;
1776         const struct lu_env  *env = NULL;
1777         struct cl_io   *io = NULL;
1778         struct cl_page *page;
1779         struct ll_sb_info *sbi = ll_i2sbi(inode);
1780         int result;
1781         ENTRY;
1782
1783         lcc = ll_cl_find(file);
1784         if (lcc != NULL) {
1785                 env = lcc->lcc_env;
1786                 io  = lcc->lcc_io;
1787         }
1788
1789         if (io == NULL) { /* fast read */
1790                 struct inode *inode = file_inode(file);
1791                 struct ll_file_data *fd = file->private_data;
1792                 struct ll_readahead_state *ras = &fd->fd_ras;
1793                 struct lu_env  *local_env = NULL;
1794                 struct vvp_page *vpg;
1795
1796                 result = -ENODATA;
1797
1798                 /* TODO: need to verify the layout version to make sure
1799                  * the page is not invalid due to layout change. */
1800                 page = cl_vmpage_page(vmpage, clob);
1801                 if (page == NULL) {
1802                         unlock_page(vmpage);
1803                         ll_ra_stats_inc_sbi(sbi, RA_STAT_FAILED_FAST_READ);
1804                         RETURN(result);
1805                 }
1806
1807                 vpg = cl2vvp_page(cl_object_page_slice(page->cp_obj, page));
1808                 if (vpg->vpg_defer_uptodate) {
1809                         enum ras_update_flags flags = LL_RAS_HIT;
1810
1811                         if (lcc && lcc->lcc_type == LCC_MMAP)
1812                                 flags |= LL_RAS_MMAP;
1813
1814                         /* For fast read, it updates read ahead state only
1815                          * if the page is hit in cache because non cache page
1816                          * case will be handled by slow read later. */
1817                         ras_update(sbi, inode, ras, vvp_index(vpg), flags, io);
1818                         /* avoid duplicate ras_update() call */
1819                         vpg->vpg_ra_updated = 1;
1820
1821                         if (ll_use_fast_io(file, ras, vvp_index(vpg)))
1822                                 result = 0;
1823                 }
1824
1825                 if (!env) {
1826                         local_env = cl_env_percpu_get();
1827                         env = local_env;
1828                 }
1829
1830                 /* export the page and skip io stack */
1831                 if (result == 0) {
1832                         vpg->vpg_ra_used = 1;
1833                         cl_page_export(env, page, 1);
1834                 } else {
1835                         ll_ra_stats_inc_sbi(sbi, RA_STAT_FAILED_FAST_READ);
1836                 }
1837                 /* release page refcount before unlocking the page to ensure
1838                  * the object won't be destroyed in the calling path of
1839                  * cl_page_put(). Please see comment in ll_releasepage(). */
1840                 cl_page_put(env, page);
1841                 unlock_page(vmpage);
1842                 if (local_env)
1843                         cl_env_percpu_put(local_env);
1844
1845                 RETURN(result);
1846         }
1847
1848         /**
1849          * Direct read can fall back to buffered read, but DIO is done
1850          * with lockless i/o, and buffered requires LDLM locking, so in
1851          * this case we must restart without lockless.
1852          */
1853         if (file->f_flags & O_DIRECT &&
1854             lcc && lcc->lcc_type == LCC_RW &&
1855             !io->ci_dio_lock) {
1856                 unlock_page(vmpage);
1857                 io->ci_dio_lock = 1;
1858                 io->ci_need_restart = 1;
1859                 RETURN(-ENOLCK);
1860         }
1861
1862         LASSERT(io->ci_state == CIS_IO_GOING);
1863         page = cl_page_find(env, clob, vmpage->index, vmpage, CPT_CACHEABLE);
1864         if (!IS_ERR(page)) {
1865                 LASSERT(page->cp_type == CPT_CACHEABLE);
1866                 if (likely(!PageUptodate(vmpage))) {
1867                         cl_page_assume(env, io, page);
1868
1869                         result = ll_io_read_page(env, io, page, file);
1870                 } else {
1871                         /* Page from a non-object file. */
1872                         unlock_page(vmpage);
1873                         result = 0;
1874                 }
1875                 cl_page_put(env, page);
1876         } else {
1877                 unlock_page(vmpage);
1878                 result = PTR_ERR(page);
1879         }
1880         RETURN(result);
1881 }