lustre/llite/rw.c

   1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
   2  * vim:expandtab:shiftwidth=8:tabstop=8:
   3  *
   4  * Lustre Lite I/O page cache routines shared by different kernel revs
   5  *
   6  *  Copyright (c) 2001-2003 Cluster File Systems, Inc.
   7  *
   8  *   This file is part of Lustre, http://www.lustre.org.
   9  *
  10  *   Lustre is free software; you can redistribute it and/or
  11  *   modify it under the terms of version 2 of the GNU General Public
  12  *   License as published by the Free Software Foundation.
  13  *
  14  *   Lustre is distributed in the hope that it will be useful,
  15  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  *   GNU General Public License for more details.
  18  *
  19  *   You should have received a copy of the GNU General Public License
  20  *   along with Lustre; if not, write to the Free Software
  21  *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22  */
  23
  24 #include <linux/config.h>
  25 #include <linux/kernel.h>
  26 #include <linux/mm.h>
  27 #include <linux/string.h>
  28 #include <linux/stat.h>
  29 #include <linux/errno.h>
  30 #include <linux/smp_lock.h>
  31 #include <linux/unistd.h>
  32 #include <linux/version.h>
  33 #include <asm/system.h>
  34 #include <asm/uaccess.h>
  35
  36 #include <linux/fs.h>
  37 #include <linux/stat.h>
  38 #include <asm/uaccess.h>
  39 #include <asm/segment.h>
  40 #include <linux/mm.h>
  41 #include <linux/pagemap.h>
  42 #include <linux/smp_lock.h>
  43
  44 #define DEBUG_SUBSYSTEM S_LLITE
  45
  46 #include <linux/lustre_mds.h>
  47 #include <linux/lustre_lite.h>
  48 #include "llite_internal.h"
  49 #include <linux/lustre_compat25.h>
  50
  51 #ifndef list_for_each_prev_safe
  52 #define list_for_each_prev_safe(pos, n, head) \
  53         for (pos = (head)->prev, n = pos->prev; pos != (head); \
  54                 pos = n, n = pos->prev )
  55 #endif
  56
  57 kmem_cache_t *ll_async_page_slab = NULL;
  58 size_t ll_async_page_slab_size = 0;
  59
  60 /* SYNCHRONOUS I/O to object storage for an inode */
  61 static int ll_brw(int cmd, struct inode *inode, struct obdo *oa,
  62                   struct page *page, int flags)
  63 {
  64         struct ll_inode_info *lli = ll_i2info(inode);
  65         struct lov_stripe_md *lsm = lli->lli_smd;
  66         struct brw_page pg;
  67         int rc;
  68         ENTRY;
  69
  70         pg.pg = page;
  71         pg.off = ((obd_off)page->index) << PAGE_SHIFT;
  72
  73         if (cmd == OBD_BRW_WRITE && (pg.off + PAGE_SIZE > inode->i_size))
  74                 pg.count = inode->i_size % PAGE_SIZE;
  75         else
  76                 pg.count = PAGE_SIZE;
  77
  78         LL_CDEBUG_PAGE(D_PAGE, page, "%s %d bytes ino %lu at "LPU64"/"LPX64"\n",
  79                        cmd & OBD_BRW_WRITE ? "write" : "read", pg.count,
  80                        inode->i_ino, pg.off, pg.off);
  81         if (pg.count == 0) {
  82                 CERROR("ZERO COUNT: ino %lu: size %p:%Lu(%p:%Lu) idx %lu off "
  83                        LPU64"\n",
  84                        inode->i_ino, inode, inode->i_size, page->mapping->host,
  85                        page->mapping->host->i_size, page->index, pg.off);
  86         }
  87
  88         pg.flag = flags;
  89
  90         if (cmd == OBD_BRW_WRITE)
  91                 lprocfs_counter_add(ll_i2sbi(inode)->ll_stats,
  92                                     LPROC_LL_BRW_WRITE, pg.count);
  93         else
  94                 lprocfs_counter_add(ll_i2sbi(inode)->ll_stats,
  95                                     LPROC_LL_BRW_READ, pg.count);
  96         rc = obd_brw(cmd, ll_i2obdexp(inode), oa, lsm, 1, &pg, NULL);
  97         if (rc == 0)
  98                 obdo_to_inode(inode, oa, OBD_MD_FLBLOCKS);
  99         else if (rc != -EIO)
 100                 CERROR("error from obd_brw: rc = %d\n", rc);
 101         RETURN(rc);
 102 }
 103
 104 __u64 lov_merge_size(struct lov_stripe_md *lsm, int kms);
 105
 106 /* this isn't where truncate starts.   roughly:
 107  * sys_truncate->ll_setattr_raw->vmtruncate->ll_truncate
 108  * we grab the lock back in setattr_raw to avoid races.
 109  *
 110  * must be called with lli_size_sem held */
 111 void ll_truncate(struct inode *inode)
 112 {
 113         struct ll_inode_info *lli = ll_i2info(inode);
 114         struct lov_stripe_md *lsm = lli->lli_smd;
 115         struct obdo oa;
 116         int rc;
 117         ENTRY;
 118         CDEBUG(D_VFSTRACE, "VFS Op:inode=%lu/%u(%p) to %Lu=%#Lx\n",inode->i_ino,
 119                inode->i_generation, inode, inode->i_size, inode->i_size);
 120
 121         if (lli->lli_size_pid != current->pid) {
 122                 EXIT;
 123                 return;
 124         }
 125
 126         if (!lsm) {
 127                 CDEBUG(D_INODE, "truncate on inode %lu with no objects\n",
 128                        inode->i_ino);
 129                 GOTO(out_unlock, 0);
 130         }
 131
 132         LASSERT(atomic_read(&lli->lli_size_sem.count) <= 0);
 133
 134         /* XXX I'm pretty sure this is a hack to paper over a more fundamental
 135          * race condition. */
 136         if (lov_merge_size(lsm, 0) == inode->i_size) {
 137                 CDEBUG(D_VFSTRACE, "skipping punch for obj "LPX64", %Lu=%#Lx\n",
 138                        lsm->lsm_object_id, inode->i_size, inode->i_size);
 139                 GOTO(out_unlock, 0);
 140         }
 141
 142         if (unlikely((ll_i2sbi(inode)->ll_flags & LL_SBI_CHECKSUM) &&
 143                      (inode->i_size & ~PAGE_MASK))) {
 144                 /* If the truncate leaves behind a partial page, update its
 145                  * checksum. */
 146                 struct page *page = find_get_page(inode->i_mapping,
 147                                              inode->i_size >> PAGE_CACHE_SHIFT);
 148                 if (page != NULL) {
 149                         struct ll_async_page *llap = llap_cast_private(page);
 150                         if (llap != NULL) {
 151                                 llap->llap_checksum =
 152                                         crc32_le(0, kmap(page), PAGE_SIZE);
 153                                 kunmap(page);
 154                         }
 155                         page_cache_release(page);
 156                 }
 157         }
 158
 159         CDEBUG(D_INFO, "calling punch for "LPX64" (new size %Lu=%#Lx)\n",
 160                lsm->lsm_object_id, inode->i_size, inode->i_size);
 161
 162         oa.o_id = lsm->lsm_object_id;
 163         oa.o_valid = OBD_MD_FLID;
 164         obdo_from_inode(&oa, inode, OBD_MD_FLTYPE | OBD_MD_FLMODE |
 165                         OBD_MD_FLATIME |OBD_MD_FLMTIME |OBD_MD_FLCTIME);
 166
 167         obd_adjust_kms(ll_i2obdexp(inode), lsm, inode->i_size, 1);
 168
 169         lli->lli_size_pid = 0;
 170         up(&lli->lli_size_sem);
 171
 172         rc = obd_punch(ll_i2obdexp(inode), &oa, lsm, inode->i_size,
 173                        OBD_OBJECT_EOF, NULL);
 174         if (rc)
 175                 CERROR("obd_truncate fails (%d) ino %lu\n", rc, inode->i_ino);
 176         else
 177                 obdo_to_inode(inode, &oa, OBD_MD_FLSIZE|OBD_MD_FLBLOCKS|
 178                               OBD_MD_FLATIME | OBD_MD_FLMTIME |
 179                               OBD_MD_FLCTIME);
 180         EXIT;
 181         return;
 182
 183  out_unlock:
 184         lli->lli_size_pid = 0;
 185         up(&lli->lli_size_sem);
 186 } /* ll_truncate */
 187
 188 __u64 lov_merge_size(struct lov_stripe_md *lsm, int kms);
 189 int ll_prepare_write(struct file *file, struct page *page, unsigned from,
 190                      unsigned to)
 191 {
 192         struct inode *inode = page->mapping->host;
 193         struct ll_inode_info *lli = ll_i2info(inode);
 194         struct lov_stripe_md *lsm = lli->lli_smd;
 195         obd_off offset = ((obd_off)page->index) << PAGE_SHIFT;
 196         struct brw_page pga;
 197         struct obdo oa;
 198         __u64 kms;
 199         int rc = 0;
 200         ENTRY;
 201
 202         LASSERT(PageLocked(page));
 203         (void)llap_cast_private(page); /* assertion */
 204
 205         /* Check to see if we should return -EIO right away */
 206         pga.pg = page;
 207         pga.off = offset;
 208         pga.count = PAGE_SIZE;
 209         pga.flag = 0;
 210
 211         oa.o_id = lsm->lsm_object_id;
 212         oa.o_mode = inode->i_mode;
 213         oa.o_valid = OBD_MD_FLID | OBD_MD_FLMODE | OBD_MD_FLTYPE;
 214
 215         rc = obd_brw(OBD_BRW_CHECK, ll_i2obdexp(inode), &oa, lsm, 1, &pga,
 216                      NULL);
 217         if (rc)
 218                 RETURN(rc);
 219
 220         if (PageUptodate(page)) {
 221                 LL_CDEBUG_PAGE(D_PAGE, page, "uptodate\n");
 222                 RETURN(0);
 223         }
 224
 225         /* We're completely overwriting an existing page, so _don't_ set it up
 226          * to date until commit_write */
 227         if (from == 0 && to == PAGE_SIZE) {
 228                 LL_CDEBUG_PAGE(D_PAGE, page, "full page write\n");
 229                 POISON_PAGE(page, 0x11);
 230                 RETURN(0);
 231         }
 232
 233         /* If are writing to a new page, no need to read old data.  The extent
 234          * locking will have updated the KMS, and for our purposes here we can
 235          * treat it like i_size. */
 236         down(&lli->lli_size_sem);
 237         kms = lov_merge_size(lsm, 1);
 238         up(&lli->lli_size_sem);
 239         if (kms <= offset) {
 240                 LL_CDEBUG_PAGE(D_PAGE, page, "kms "LPU64" <= offset "LPU64"\n",
 241                                kms, offset);
 242                 memset(kmap(page), 0, PAGE_SIZE);
 243                 kunmap(page);
 244                 GOTO(prepare_done, rc = 0);
 245         }
 246
 247         /* XXX could be an async ocp read.. read-ahead? */
 248         rc = ll_brw(OBD_BRW_READ, inode, &oa, page, 0);
 249         if (rc == 0) {
 250                 /* bug 1598: don't clobber blksize */
 251                 oa.o_valid &= ~(OBD_MD_FLSIZE | OBD_MD_FLBLKSZ);
 252                 obdo_refresh_inode(inode, &oa, oa.o_valid);
 253         }
 254
 255         EXIT;
 256  prepare_done:
 257         if (rc == 0)
 258                 SetPageUptodate(page);
 259
 260         return rc;
 261 }
 262
 263 struct ll_async_page *llap_from_cookie(void *cookie)
 264 {
 265         struct ll_async_page *llap = cookie;
 266         if (llap->llap_magic != LLAP_MAGIC)
 267                 return ERR_PTR(-EINVAL);
 268         return llap;
 269 };
 270
 271 static int ll_ap_make_ready(void *data, int cmd)
 272 {
 273         struct ll_async_page *llap;
 274         struct page *page;
 275         ENTRY;
 276
 277         llap = llap_from_cookie(data);
 278         if (IS_ERR(llap))
 279                 RETURN(-EINVAL);
 280
 281         page = llap->llap_page;
 282
 283         LASSERT(cmd != OBD_BRW_READ);
 284
 285         /* we're trying to write, but the page is locked.. come back later */
 286         if (TryLockPage(page))
 287                 RETURN(-EAGAIN);
 288
 289         LL_CDEBUG_PAGE(D_PAGE, page, "made ready\n");
 290         page_cache_get(page);
 291
 292         /* if we left PageDirty we might get another writepage call
 293          * in the future.  list walkers are bright enough
 294          * to check page dirty so we can leave it on whatever list
 295          * its on.  XXX also, we're called with the cli list so if
 296          * we got the page cache list we'd create a lock inversion
 297          * with the removepage path which gets the page lock then the
 298          * cli lock */
 299         clear_page_dirty(page);
 300         RETURN(0);
 301 }
 302
 303 /* We have two reasons for giving llite the opportunity to change the
 304  * write length of a given queued page as it builds the RPC containing
 305  * the page:
 306  *
 307  * 1) Further extending writes may have landed in the page cache
 308  *    since a partial write first queued this page requiring us
 309  *    to write more from the page cache.  (No further races are possible, since
 310  *    by the time this is called, the page is locked.)
 311  * 2) We might have raced with truncate and want to avoid performing
 312  *    write RPCs that are just going to be thrown away by the
 313  *    truncate's punch on the storage targets.
 314  *
 315  * The kms serves these purposes as it is set at both truncate and extending
 316  * writes.
 317  */
 318 static int ll_ap_refresh_count(void *data, int cmd)
 319 {
 320         struct ll_inode_info *lli;
 321         struct ll_async_page *llap;
 322         struct lov_stripe_md *lsm;
 323         struct page *page;
 324         __u64 kms;
 325         ENTRY;
 326
 327         /* readpage queues with _COUNT_STABLE, shouldn't get here. */
 328         LASSERT(cmd != OBD_BRW_READ);
 329
 330         llap = llap_from_cookie(data);
 331         if (IS_ERR(llap))
 332                 RETURN(PTR_ERR(llap));
 333
 334         page = llap->llap_page;
 335         lli = ll_i2info(page->mapping->host);
 336         lsm = lli->lli_smd;
 337
 338         //down(&lli->lli_size_sem);
 339         kms = lov_merge_size(lsm, 1);
 340         //up(&lli->lli_size_sem);
 341
 342         /* catch race with truncate */
 343         if (((__u64)page->index << PAGE_SHIFT) >= kms)
 344                 return 0;
 345
 346         /* catch sub-page write at end of file */
 347         if (((__u64)page->index << PAGE_SHIFT) + PAGE_SIZE > kms)
 348                 return kms % PAGE_SIZE;
 349
 350         return PAGE_SIZE;
 351 }
 352
 353 void ll_inode_fill_obdo(struct inode *inode, int cmd, struct obdo *oa)
 354 {
 355         struct lov_stripe_md *lsm;
 356         obd_flag valid_flags;
 357
 358         lsm = ll_i2info(inode)->lli_smd;
 359
 360         oa->o_id = lsm->lsm_object_id;
 361         oa->o_valid = OBD_MD_FLID;
 362         valid_flags = OBD_MD_FLTYPE | OBD_MD_FLATIME;
 363         if (cmd == OBD_BRW_WRITE) {
 364                 oa->o_valid |= OBD_MD_FLIFID | OBD_MD_FLEPOCH;
 365                 mdc_pack_fid(obdo_fid(oa), inode->i_ino, 0, inode->i_mode);
 366                 oa->o_easize = ll_i2info(inode)->lli_io_epoch;
 367                 oa->o_uid = inode->i_uid;
 368                 oa->o_gid = inode->i_gid;
 369
 370                 valid_flags |= OBD_MD_FLMTIME | OBD_MD_FLCTIME |
 371                                OBD_MD_FLUID | OBD_MD_FLGID;
 372         }
 373
 374         obdo_from_inode(oa, inode, valid_flags);
 375 }
 376
 377 static void ll_ap_fill_obdo(void *data, int cmd, struct obdo *oa)
 378 {
 379         struct ll_async_page *llap;
 380         ENTRY;
 381
 382         llap = llap_from_cookie(data);
 383         if (IS_ERR(llap)) {
 384                 EXIT;
 385                 return;
 386         }
 387
 388         ll_inode_fill_obdo(llap->llap_page->mapping->host, cmd, oa);
 389         EXIT;
 390 }
 391
 392 static void ll_ap_get_ucred(void *data, struct obd_ucred *ouc)
 393 {
 394         struct ll_async_page *llap;
 395
 396         llap = llap_from_cookie(data);
 397         if (IS_ERR(llap)) {
 398                 EXIT;
 399                 return;
 400         }
 401
 402         memcpy(ouc, &llap->llap_ouc, sizeof(*ouc));
 403         EXIT;
 404 }
 405
 406 static struct obd_async_page_ops ll_async_page_ops = {
 407         .ap_make_ready =        ll_ap_make_ready,
 408         .ap_refresh_count =     ll_ap_refresh_count,
 409         .ap_fill_obdo =         ll_ap_fill_obdo,
 410         .ap_completion =        ll_ap_completion,
 411         .ap_get_ucred =         ll_ap_get_ucred,
 412 };
 413
 414 struct ll_async_page *llap_cast_private(struct page *page)
 415 {
 416         struct ll_async_page *llap = (struct ll_async_page *)page->private;
 417
 418         LASSERTF(llap == NULL || llap->llap_magic == LLAP_MAGIC,
 419                  "page %p private %lu gave magic %d which != %d\n",
 420                  page, page->private, llap->llap_magic, LLAP_MAGIC);
 421
 422         return llap;
 423 }
 424
 425 /* Try to shrink the page cache for the @sbi filesystem by 1/@shrink_fraction.
 426  *
 427  * There is an llap attached onto every page in lustre, linked off @sbi.
 428  * We add an llap to the list so we don't lose our place during list walking.
 429  * If llaps in the list are being moved they will only move to the end
 430  * of the LRU, and we aren't terribly interested in those pages here (we
 431  * start at the beginning of the list where the least-used llaps are.
 432  */
 433 int llap_shrink_cache(struct ll_sb_info *sbi, int shrink_fraction)
 434 {
 435         struct ll_async_page *llap, dummy_llap = { .llap_magic = 0xd11ad11a };
 436         unsigned long total, want, count = 0;
 437
 438         total = sbi->ll_async_page_count;
 439
 440         /* There can be a large number of llaps (600k or more in a large
 441          * memory machine) so the VM 1/6 shrink ratio is likely too much.
 442          * Since we are freeing pages also, we don't necessarily want to
 443          * shrink so much.  Limit to 40MB of pages + llaps per call. */
 444         if (shrink_fraction == 0)
 445                 want = sbi->ll_async_page_count - sbi->ll_async_page_max + 32;
 446         else
 447                 want = (total + shrink_fraction - 1) / shrink_fraction;
 448
 449         if (want > 40 << (20 - PAGE_CACHE_SHIFT))
 450                 want = 40 << (20 - PAGE_CACHE_SHIFT);
 451
 452         CDEBUG(D_CACHE, "shrinking %lu of %lu pages (1/%d)\n",
 453                want, total, shrink_fraction);
 454
 455         spin_lock(&sbi->ll_lock);
 456         list_add(&dummy_llap.llap_pglist_item, &sbi->ll_pglist);
 457
 458         while (--total >= 0 && count < want) {
 459                 struct page *page;
 460                 int keep;
 461
 462                 if (unlikely(need_resched())) {
 463                         spin_unlock(&sbi->ll_lock);
 464                         cond_resched();
 465                         spin_lock(&sbi->ll_lock);
 466                 }
 467
 468                 llap = llite_pglist_next_llap(sbi,&dummy_llap.llap_pglist_item);
 469                 list_del_init(&dummy_llap.llap_pglist_item);
 470                 if (llap == NULL)
 471                         break;
 472
 473                 page = llap->llap_page;
 474                 LASSERT(page != NULL);
 475
 476                 list_add(&dummy_llap.llap_pglist_item, &llap->llap_pglist_item);
 477
 478                 /* Page needs/undergoing IO */
 479                 if (TryLockPage(page)) {
 480                         LL_CDEBUG_PAGE(D_PAGE, page, "can't lock\n");
 481                         continue;
 482                 }
 483
 484                 if (llap->llap_write_queued || PageDirty(page) ||
 485                     (!PageUptodate(page) &&
 486                      llap->llap_origin != LLAP_ORIGIN_READAHEAD))
 487                         keep = 1;
 488                 else
 489                         keep = 0;
 490
 491                 LL_CDEBUG_PAGE(D_PAGE, page,"%s LRU page: %s%s%s%s origin %s\n",
 492                                keep ? "keep" : "drop",
 493                                llap->llap_write_queued ? "wq " : "",
 494                                PageDirty(page) ? "pd " : "",
 495                                PageUptodate(page) ? "" : "!pu ",
 496                                llap->llap_defer_uptodate ? "" : "!du",
 497                                llap_origins[llap->llap_origin]);
 498
 499                 /* If page is dirty or undergoing IO don't discard it */
 500                 if (keep) {
 501                         unlock_page(page);
 502                         continue;
 503                 }
 504
 505                 page_cache_get(page);
 506                 spin_unlock(&sbi->ll_lock);
 507
 508                 ++count;
 509                 if (page->mapping != NULL) {
 510                         ll_ra_accounting(page, page->mapping);
 511                         ll_truncate_complete_page(page);
 512                 }
 513                 unlock_page(page);
 514                 page_cache_release(page);
 515
 516                 spin_lock(&sbi->ll_lock);
 517         }
 518         list_del(&dummy_llap.llap_pglist_item);
 519         spin_unlock(&sbi->ll_lock);
 520
 521         CDEBUG(D_CACHE, "shrank %lu/%lu and left %lu unscanned\n",
 522                count, want, total);
 523
 524         return count;
 525 }
 526
 527 struct ll_async_page *llap_from_page(struct page *page, unsigned origin)
 528 {
 529         struct ll_async_page *llap;
 530         struct obd_export *exp;
 531         struct inode *inode = page->mapping->host;
 532         struct ll_sb_info *sbi = ll_i2sbi(inode);
 533         int rc;
 534         ENTRY;
 535
 536         LASSERT(ll_async_page_slab);
 537         LASSERTF(origin < LLAP__ORIGIN_MAX, "%u\n", origin);
 538
 539         llap = llap_cast_private(page);
 540         if (llap != NULL) {
 541                 /* move to end of LRU list */
 542                 spin_lock(&sbi->ll_lock);
 543                 sbi->ll_pglist_gen++;
 544                 list_del_init(&llap->llap_pglist_item);
 545                 list_add_tail(&llap->llap_pglist_item, &sbi->ll_pglist);
 546                 spin_unlock(&sbi->ll_lock);
 547                 GOTO(out, llap);
 548         }
 549
 550         exp = ll_i2obdexp(page->mapping->host);
 551         if (exp == NULL)
 552                 RETURN(ERR_PTR(-EINVAL));
 553
 554         /* limit the number of lustre-cached pages */
 555         if (sbi->ll_async_page_count >= sbi->ll_async_page_max)
 556                 llap_shrink_cache(sbi, 0);
 557
 558         OBD_SLAB_ALLOC(llap, ll_async_page_slab, SLAB_KERNEL,
 559                        ll_async_page_slab_size);
 560         if (llap == NULL)
 561                 RETURN(ERR_PTR(-ENOMEM));
 562         llap->llap_magic = LLAP_MAGIC;
 563         llap->llap_cookie = (void *)llap + size_round(sizeof(*llap));
 564
 565         rc = obd_prep_async_page(exp, ll_i2info(inode)->lli_smd, NULL, page,
 566                                  (obd_off)page->index << PAGE_SHIFT,
 567                                  &ll_async_page_ops, llap, &llap->llap_cookie);
 568         if (rc) {
 569                 OBD_SLAB_FREE(llap, ll_async_page_slab,
 570                               ll_async_page_slab_size);
 571                 RETURN(ERR_PTR(rc));
 572         }
 573
 574         CDEBUG(D_CACHE, "llap %p page %p cookie %p obj off "LPU64"\n", llap,
 575                page, llap->llap_cookie, (obd_off)page->index << PAGE_SHIFT);
 576         /* also zeroing the PRIVBITS low order bitflags */
 577         __set_page_ll_data(page, llap);
 578         llap->llap_page = page;
 579
 580         spin_lock(&sbi->ll_lock);
 581         sbi->ll_pglist_gen++;
 582         sbi->ll_async_page_count++;
 583         list_add_tail(&llap->llap_pglist_item, &sbi->ll_pglist);
 584         spin_unlock(&sbi->ll_lock);
 585
 586  out:
 587         if (unlikely(sbi->ll_flags & LL_SBI_CHECKSUM)) {
 588                 __u32 csum = 0;
 589                 csum = crc32_le(csum, kmap(page), PAGE_SIZE);
 590                 kunmap(page);
 591                 if (origin == LLAP_ORIGIN_READAHEAD ||
 592                     origin == LLAP_ORIGIN_READPAGE) {
 593                         llap->llap_checksum = 0;
 594                 } else if (origin == LLAP_ORIGIN_COMMIT_WRITE ||
 595                            llap->llap_checksum == 0) {
 596                         llap->llap_checksum = csum;
 597                         CDEBUG(D_PAGE, "page %p cksum %x\n", page, csum);
 598                 } else if (llap->llap_checksum == csum) {
 599                         /* origin == LLAP_ORIGIN_WRITEPAGE */
 600                         CDEBUG(D_PAGE, "page %p cksum %x confirmed\n",
 601                                page, csum);
 602                 } else {
 603                         /* origin == LLAP_ORIGIN_WRITEPAGE */
 604                         LL_CDEBUG_PAGE(D_ERROR, page, "old cksum %x != new "
 605                                        "%x!\n", llap->llap_checksum, csum);
 606                 }
 607         }
 608
 609         llap->llap_origin = origin;
 610         RETURN(llap);
 611 }
 612
 613 static int queue_or_sync_write(struct obd_export *exp, struct inode *inode,
 614                                struct ll_async_page *llap,
 615                                unsigned to, obd_flag async_flags)
 616 {
 617         unsigned long size_index = inode->i_size >> PAGE_SHIFT;
 618         struct obd_io_group *oig;
 619         struct ll_sb_info *sbi = ll_i2sbi(inode);
 620         int rc;
 621         ENTRY;
 622
 623         /* _make_ready only sees llap once we've unlocked the page */
 624         llap->llap_write_queued = 1;
 625         rc = obd_queue_async_io(exp, ll_i2info(inode)->lli_smd, NULL,
 626                                 llap->llap_cookie, OBD_BRW_WRITE, 0, 0, 0,
 627                                 async_flags);
 628         if (rc == 0) {
 629                 LL_CDEBUG_PAGE(D_PAGE, llap->llap_page, "write queued\n");
 630                 //llap_write_pending(inode, llap);
 631                 GOTO(out, 0);
 632         }
 633
 634         llap->llap_write_queued = 0;
 635
 636         rc = oig_init(&oig);
 637         if (rc)
 638                 GOTO(out, rc);
 639
 640         /* make full-page requests if we are not at EOF (bug 4410) */
 641         if (to != PAGE_SIZE && llap->llap_page->index < size_index) {
 642                 LL_CDEBUG_PAGE(D_PAGE, llap->llap_page,
 643                                "sync write before EOF: size_index %lu, to %d\n",
 644                                size_index, to);
 645                 to = PAGE_SIZE;
 646         } else if (to != PAGE_SIZE && llap->llap_page->index == size_index) {
 647                 int size_to = inode->i_size & ~PAGE_MASK;
 648                 LL_CDEBUG_PAGE(D_PAGE, llap->llap_page,
 649                                "sync write at EOF: size_index %lu, to %d/%d\n",
 650                                size_index, to, size_to);
 651                 if (to < size_to)
 652                         to = size_to;
 653         }
 654
 655         /* compare the checksum once before the page leaves llite */
 656         if (unlikely((sbi->ll_flags & LL_SBI_CHECKSUM) &&
 657                      llap->llap_checksum != 0)) {
 658                 __u32 csum = 0;
 659                 struct page *page = llap->llap_page;
 660                 csum = crc32_le(csum, kmap(page), PAGE_SIZE);
 661                 kunmap(page);
 662                 if (llap->llap_checksum == csum) {
 663                         CDEBUG(D_PAGE, "page %p cksum %x confirmed\n",
 664                                page, csum);
 665                 } else {
 666                         CERROR("page %p old cksum %x != new cksum %x!\n",
 667                                page, llap->llap_checksum, csum);
 668                 }
 669         }
 670
 671         rc = obd_queue_group_io(exp, ll_i2info(inode)->lli_smd, NULL, oig,
 672                                 llap->llap_cookie, OBD_BRW_WRITE, 0, to, 0,
 673                                 ASYNC_READY | ASYNC_URGENT |
 674                                 ASYNC_COUNT_STABLE | ASYNC_GROUP_SYNC);
 675         if (rc)
 676                 GOTO(free_oig, rc);
 677
 678         rc = obd_trigger_group_io(exp, ll_i2info(inode)->lli_smd, NULL, oig);
 679         if (rc)
 680                 GOTO(free_oig, rc);
 681
 682         rc = oig_wait(oig);
 683
 684         if (!rc && async_flags & ASYNC_READY)
 685                 unlock_page(llap->llap_page);
 686
 687         LL_CDEBUG_PAGE(D_PAGE, llap->llap_page, "sync write returned %d\n", rc);
 688
 689 free_oig:
 690         oig_release(oig);
 691 out:
 692         RETURN(rc);
 693 }
 694
 695 /* update our write count to account for i_size increases that may have
 696  * happened since we've queued the page for io. */
 697
 698 /* be careful not to return success without setting the page Uptodate or
 699  * the next pass through prepare_write will read in stale data from disk. */
 700 int ll_commit_write(struct file *file, struct page *page, unsigned from,
 701                     unsigned to)
 702 {
 703         struct inode *inode = page->mapping->host;
 704         struct ll_inode_info *lli = ll_i2info(inode);
 705         struct lov_stripe_md *lsm = lli->lli_smd;
 706         struct obd_export *exp;
 707         struct ll_async_page *llap;
 708         struct ll_uctxt ctxt;
 709         loff_t size;
 710         int rc = 0;
 711         ENTRY;
 712
 713         SIGNAL_MASK_ASSERT(); /* XXX BUG 1511 */
 714         LASSERT(inode == file->f_dentry->d_inode);
 715         LASSERT(PageLocked(page));
 716
 717         CDEBUG(D_INODE, "inode %p is writing page %p from %d to %d at %lu\n",
 718                inode, page, from, to, page->index);
 719
 720         llap = llap_from_page(page, LLAP_ORIGIN_COMMIT_WRITE);
 721         if (IS_ERR(llap))
 722                 RETURN(PTR_ERR(llap));
 723
 724         exp = ll_i2obdexp(inode);
 725         if (exp == NULL)
 726                 RETURN(-EINVAL);
 727
 728         /* set user credit information for this page */
 729         llap->llap_ouc.ouc_fsuid = current->fsuid;
 730         llap->llap_ouc.ouc_fsgid = current->fsgid;
 731         llap->llap_ouc.ouc_cap = current->cap_effective;
 732         ll_i2uctxt(&ctxt, inode, NULL);
 733         llap->llap_ouc.ouc_suppgid1 = ctxt.gid1;
 734
 735         /* queue a write for some time in the future the first time we
 736          * dirty the page */
 737         if (!PageDirty(page)) {
 738                 lprocfs_counter_incr(ll_i2sbi(inode)->ll_stats,
 739                                      LPROC_LL_DIRTY_MISSES);
 740
 741                 rc = queue_or_sync_write(exp, inode, llap, to, 0);
 742                 if (rc)
 743                         GOTO(out, rc);
 744         } else {
 745                 lprocfs_counter_incr(ll_i2sbi(inode)->ll_stats,
 746                                      LPROC_LL_DIRTY_HITS);
 747         }
 748
 749         /* put the page in the page cache, from now on ll_removepage is
 750          * responsible for cleaning up the llap.
 751          * only set page dirty when it's queued to be write out */
 752         if (llap->llap_write_queued)
 753                 set_page_dirty(page);
 754
 755 out:
 756         size = (((obd_off)page->index) << PAGE_SHIFT) + to;
 757         down(&lli->lli_size_sem);
 758         if (rc == 0) {
 759                 obd_adjust_kms(exp, lsm, size, 0);
 760                 if (size > inode->i_size)
 761                         inode->i_size = size;
 762                 SetPageUptodate(page);
 763         } else if (size > inode->i_size) {
 764                 /* this page beyond the pales of i_size, so it can't be
 765                  * truncated in ll_p_r_e during lock revoking. we must
 766                  * teardown our book-keeping here. */
 767                 ll_removepage(page);
 768         }
 769         up(&lli->lli_size_sem);
 770         RETURN(rc);
 771 }
 772
 773 static unsigned long ll_ra_count_get(struct ll_sb_info *sbi, unsigned long len)
 774 {
 775         struct ll_ra_info *ra = &sbi->ll_ra_info;
 776         unsigned long ret;
 777         ENTRY;
 778
 779         spin_lock(&sbi->ll_lock);
 780         ret = min(ra->ra_max_pages - ra->ra_cur_pages, len);
 781         ra->ra_cur_pages += ret;
 782         spin_unlock(&sbi->ll_lock);
 783
 784         RETURN(ret);
 785 }
 786
 787 static void ll_ra_count_put(struct ll_sb_info *sbi, unsigned long len)
 788 {
 789         struct ll_ra_info *ra = &sbi->ll_ra_info;
 790         spin_lock(&sbi->ll_lock);
 791         LASSERTF(ra->ra_cur_pages >= len, "r_c_p %lu len %lu\n",
 792                  ra->ra_cur_pages, len);
 793         ra->ra_cur_pages -= len;
 794         spin_unlock(&sbi->ll_lock);
 795 }
 796
 797 /* called for each page in a completed rpc.*/
 798 void ll_ap_completion(void *data, int cmd, struct obdo *oa, int rc)
 799 {
 800         struct ll_async_page *llap;
 801         struct page *page;
 802         ENTRY;
 803
 804         llap = llap_from_cookie(data);
 805         if (IS_ERR(llap)) {
 806                 EXIT;
 807                 return;
 808         }
 809
 810         page = llap->llap_page;
 811         LASSERT(PageLocked(page));
 812
 813         LL_CDEBUG_PAGE(D_PAGE, page, "completing cmd %d with %d\n", cmd, rc);
 814
 815         if (cmd == OBD_BRW_READ && llap->llap_defer_uptodate)
 816                 ll_ra_count_put(ll_i2sbi(page->mapping->host), 1);
 817
 818         if (rc == 0)  {
 819                 if (cmd == OBD_BRW_READ) {
 820                         if (!llap->llap_defer_uptodate)
 821                                 SetPageUptodate(page);
 822                 } else {
 823                         llap->llap_write_queued = 0;
 824                 }
 825                 ClearPageError(page);
 826         } else {
 827                 if (cmd == OBD_BRW_READ) {
 828                         llap->llap_defer_uptodate = 0;
 829                 } else {
 830                         ll_redirty_page(page);
 831                 }
 832                 SetPageError(page);
 833         }
 834
 835         unlock_page(page);
 836
 837         if (0 && cmd == OBD_BRW_WRITE) {
 838                 llap_write_complete(page->mapping->host, llap);
 839                 ll_try_done_writing(page->mapping->host);
 840         }
 841
 842         if (PageWriteback(page)) {
 843                 end_page_writeback(page);
 844         }
 845         page_cache_release(page);
 846         EXIT;
 847 }
 848
 849 /* the kernel calls us here when a page is unhashed from the page cache.
 850  * the page will be locked and the kernel is holding a spinlock, so
 851  * we need to be careful.  we're just tearing down our book-keeping
 852  * here. */
 853 void ll_removepage(struct page *page)
 854 {
 855         struct inode *inode = page->mapping->host;
 856         struct obd_export *exp;
 857         struct ll_async_page *llap;
 858         struct ll_sb_info *sbi = ll_i2sbi(inode);
 859         int rc;
 860         ENTRY;
 861
 862         LASSERT(!in_interrupt());
 863
 864         /* sync pages or failed read pages can leave pages in the page
 865          * cache that don't have our data associated with them anymore */
 866         if (page->private == 0) {
 867                 EXIT;
 868                 return;
 869         }
 870
 871         LL_CDEBUG_PAGE(D_PAGE, page, "being evicted\n");
 872
 873         exp = ll_i2obdexp(inode);
 874         if (exp == NULL) {
 875                 CERROR("page %p ind %lu gave null export\n", page, page->index);
 876                 EXIT;
 877                 return;
 878         }
 879
 880         llap = llap_from_page(page, 0);
 881         if (IS_ERR(llap)) {
 882                 CERROR("page %p ind %lu couldn't find llap: %ld\n", page,
 883                        page->index, PTR_ERR(llap));
 884                 EXIT;
 885                 return;
 886         }
 887
 888         //llap_write_complete(inode, llap);
 889         rc = obd_teardown_async_page(exp, ll_i2info(inode)->lli_smd, NULL,
 890                                      llap->llap_cookie);
 891         if (rc != 0)
 892                 CERROR("page %p ind %lu failed: %d\n", page, page->index, rc);
 893
 894         /* this unconditional free is only safe because the page lock
 895          * is providing exclusivity to memory pressure/truncate/writeback..*/
 896         __clear_page_ll_data(page);
 897
 898         spin_lock(&sbi->ll_lock);
 899         if (!list_empty(&llap->llap_pglist_item))
 900                 list_del_init(&llap->llap_pglist_item);
 901         sbi->ll_pglist_gen++;
 902         sbi->ll_async_page_count--;
 903         spin_unlock(&sbi->ll_lock);
 904         OBD_SLAB_FREE(llap, ll_async_page_slab, ll_async_page_slab_size);
 905         EXIT;
 906 }
 907
 908 static int ll_page_matches(struct page *page, int readahead)
 909 {
 910         struct lustre_handle match_lockh = {0};
 911         struct inode *inode = page->mapping->host;
 912         ldlm_policy_data_t page_extent;
 913         int flags, matches;
 914         ENTRY;
 915
 916         page_extent.l_extent.start = (__u64)page->index << PAGE_CACHE_SHIFT;
 917         page_extent.l_extent.end =
 918                 page_extent.l_extent.start + PAGE_CACHE_SIZE - 1;
 919         flags = LDLM_FL_TEST_LOCK;
 920         if (!readahead)
 921                 flags |= LDLM_FL_CBPENDING | LDLM_FL_BLOCK_GRANTED;
 922         matches = obd_match(ll_i2sbi(inode)->ll_osc_exp,
 923                             ll_i2info(inode)->lli_smd, LDLM_EXTENT,
 924                             &page_extent, LCK_PR | LCK_PW, &flags, inode,
 925                             &match_lockh);
 926         RETURN(matches);
 927 }
 928
 929 static int ll_issue_page_read(struct obd_export *exp,
 930                               struct ll_async_page *llap,
 931                               struct obd_io_group *oig, int defer)
 932 {
 933         struct page *page = llap->llap_page;
 934         int rc;
 935
 936         page_cache_get(page);
 937         llap->llap_defer_uptodate = defer;
 938         llap->llap_ra_used = 0;
 939         rc = obd_queue_group_io(exp, ll_i2info(page->mapping->host)->lli_smd,
 940                                 NULL, oig, llap->llap_cookie, OBD_BRW_READ, 0,
 941                                 PAGE_SIZE, 0, ASYNC_COUNT_STABLE | ASYNC_READY
 942                                               | ASYNC_URGENT);
 943         if (rc) {
 944                 LL_CDEBUG_PAGE(D_ERROR, page, "read queue failed: rc %d\n", rc);
 945                 page_cache_release(page);
 946         }
 947         RETURN(rc);
 948 }
 949
 950 static void ll_ra_stats_inc_unlocked(struct ll_ra_info *ra, enum ra_stat which)
 951 {
 952         LASSERTF(which >= 0 && which < _NR_RA_STAT, "which: %u\n", which);
 953         ra->ra_stats[which]++;
 954 }
 955
 956 static void ll_ra_stats_inc(struct address_space *mapping, enum ra_stat which)
 957 {
 958         struct ll_sb_info *sbi = ll_i2sbi(mapping->host);
 959         struct ll_ra_info *ra = &ll_i2sbi(mapping->host)->ll_ra_info;
 960
 961         spin_lock(&sbi->ll_lock);
 962         ll_ra_stats_inc_unlocked(ra, which);
 963         spin_unlock(&sbi->ll_lock);
 964 }
 965
 966 void ll_ra_accounting(struct page *page, struct address_space *mapping)
 967 {
 968         struct ll_async_page *llap;
 969
 970         llap = llap_from_page(page, LLAP_ORIGIN_WRITEPAGE);
 971         if (IS_ERR(llap))
 972                 return;
 973
 974         if (!llap->llap_defer_uptodate || llap->llap_ra_used)
 975                 return;
 976
 977         ll_ra_stats_inc(mapping, RA_STAT_DISCARDED);
 978 }
 979
 980 #define RAS_CDEBUG(ras) \
 981         CDEBUG(D_READA, "lrp %lu c %lu ws %lu wl %lu nra %lu\n",        \
 982                ras->ras_last_readpage, ras->ras_consecutive,            \
 983                ras->ras_window_start, ras->ras_window_len,              \
 984                ras->ras_next_readahead);
 985
 986 static int index_in_window(unsigned long index, unsigned long point,
 987                            unsigned long before, unsigned long after)
 988 {
 989         unsigned long start = point - before, end = point + after;
 990
 991         if (start > point)
 992                start = 0;
 993         if (end < point)
 994                end = ~0;
 995
 996         return start <= index && index <= end;
 997 }
 998
 999 static int ll_readahead(struct ll_readahead_state *ras,
1000                          struct obd_export *exp, struct address_space *mapping,
1001                          struct obd_io_group *oig, int flags)
1002 {
1003         unsigned long i, start = 0, end = 0, reserved;
1004         struct ll_async_page *llap;
1005         struct page *page;
1006         int rc, ret = 0, match_failed = 0;
1007         __u64 kms;
1008         unsigned int gfp_mask;
1009         ENTRY;
1010
1011         kms = lov_merge_size(ll_i2info(mapping->host)->lli_smd, 1);
1012         if (kms == 0) {
1013                 ll_ra_stats_inc(mapping, RA_STAT_ZERO_LEN);
1014                 RETURN(0);
1015         }
1016
1017         spin_lock(&ras->ras_lock);
1018         /* reserve a part of the read-ahead window that we'll be issuing */
1019         if (ras->ras_window_len) {
1020                 start = ras->ras_next_readahead;
1021                 end = ras->ras_window_start + ras->ras_window_len - 1;
1022                 end = min(end, (unsigned long)((kms - 1) >> PAGE_CACHE_SHIFT));
1023                 ras->ras_next_readahead = max(end, end + 1);
1024
1025                 RAS_CDEBUG(ras);
1026         }
1027         spin_unlock(&ras->ras_lock);
1028
1029         if (end == 0) {
1030                 ll_ra_stats_inc(mapping, RA_STAT_ZERO_WINDOW);
1031                 RETURN(0);
1032         }
1033
1034         reserved = ll_ra_count_get(ll_i2sbi(mapping->host), end - start + 1);
1035         if (reserved < end - start + 1)
1036                 ll_ra_stats_inc(mapping, RA_STAT_MAX_IN_FLIGHT);
1037
1038         gfp_mask = GFP_HIGHUSER & ~__GFP_WAIT;
1039 #ifdef __GFP_NOWARN
1040         gfp_mask |= __GFP_NOWARN;
1041 #endif
1042
1043         for (i = start; reserved > 0 && !match_failed && i <= end; i++) {
1044                 /* skip locked pages from previous readpage calls */
1045                 page = grab_cache_page_nowait_gfp(mapping, i, gfp_mask);
1046                 if (page == NULL) {
1047                         CDEBUG(D_READA, "g_c_p_n failed\n");
1048                         continue;
1049                 }
1050
1051                 /* we do this first so that we can see the page in the /proc
1052                  * accounting */
1053                 llap = llap_from_page(page, LLAP_ORIGIN_READAHEAD);
1054                 if (IS_ERR(llap) || llap->llap_defer_uptodate)
1055                         goto next_page;
1056
1057                 /* skip completed pages */
1058                 if (Page_Uptodate(page))
1059                         goto next_page;
1060
1061                 /* bail when we hit the end of the lock. */
1062                 if ((rc = ll_page_matches(page, 1)) <= 0) {
1063                         LL_CDEBUG_PAGE(D_READA | D_PAGE, page,
1064                                        "lock match failed: rc %d\n", rc);
1065                         ll_ra_stats_inc(mapping, RA_STAT_FAILED_MATCH);
1066                         match_failed = 1;
1067                         goto next_page;
1068                 }
1069
1070                 rc = ll_issue_page_read(exp, llap, oig, 1);
1071                 if (rc == 0) {
1072                         reserved--;
1073                         ret++;
1074                         LL_CDEBUG_PAGE(D_READA| D_PAGE, page,
1075                                        "started read-ahead\n");
1076                 }
1077                 if (rc) {
1078         next_page:
1079                         LL_CDEBUG_PAGE(D_READA | D_PAGE, page,
1080                                        "skipping read-ahead\n");
1081
1082                         unlock_page(page);
1083                 }
1084                 page_cache_release(page);
1085         }
1086
1087         LASSERTF(reserved >= 0, "reserved %lu\n", reserved);
1088         if (reserved != 0)
1089                 ll_ra_count_put(ll_i2sbi(mapping->host), reserved);
1090         if (i == end + 1 && end == (kms >> PAGE_CACHE_SHIFT))
1091                 ll_ra_stats_inc(mapping, RA_STAT_EOF);
1092
1093         /* if we didn't get to the end of the region we reserved from
1094          * the ras we need to go back and update the ras so that the
1095          * next read-ahead tries from where we left off.  we only do so
1096          * if the region we failed to issue read-ahead on is still ahead
1097          * of the app and behind the next index to start read-ahead from */
1098         if (i != end + 1) {
1099                 spin_lock(&ras->ras_lock);
1100                 if (i < ras->ras_next_readahead &&
1101                     index_in_window(i, ras->ras_window_start, 0,
1102                                     ras->ras_window_len)) {
1103                         ras->ras_next_readahead = i;
1104                         RAS_CDEBUG(ras);
1105                 }
1106                 spin_unlock(&ras->ras_lock);
1107         }
1108
1109         RETURN(ret);
1110 }
1111
1112 static void ras_set_start(struct ll_readahead_state *ras, unsigned long index)
1113 {
1114         ras->ras_window_start = index & (~(PTLRPC_MAX_BRW_PAGES - 1));
1115 }
1116
1117 /* called with the ras_lock held or from places where it doesn't matter */
1118 static void ras_reset(struct ll_readahead_state *ras, unsigned long index)
1119 {
1120         ras->ras_last_readpage = index;
1121         ras->ras_consecutive = 1;
1122         ras->ras_window_len = 0;
1123         ras_set_start(ras, index);
1124         ras->ras_next_readahead = ras->ras_window_start;
1125
1126         RAS_CDEBUG(ras);
1127 }
1128
1129 void ll_readahead_init(struct inode *inode, struct ll_readahead_state *ras)
1130 {
1131         spin_lock_init(&ras->ras_lock);
1132         ras_reset(ras, 0);
1133 }
1134
1135 static void ras_update(struct ll_sb_info *sbi, struct ll_readahead_state *ras,
1136                        unsigned long index, unsigned hit)
1137 {
1138         struct ll_ra_info *ra = &sbi->ll_ra_info;
1139         int zero = 0;
1140         ENTRY;
1141
1142         spin_lock(&sbi->ll_lock);
1143         spin_lock(&ras->ras_lock);
1144
1145         ll_ra_stats_inc_unlocked(ra, hit ? RA_STAT_HIT : RA_STAT_MISS);
1146
1147         /* reset the read-ahead window in two cases.  First when the app seeks
1148          * or reads to some other part of the file.  Secondly if we get a
1149          * read-ahead miss that we think we've previously issued.  This can
1150          * be a symptom of there being so many read-ahead pages that the VM is
1151          * reclaiming it before we get to it. */
1152         if (!index_in_window(index, ras->ras_last_readpage, 8, 8)) {
1153                 zero = 1;
1154                 ll_ra_stats_inc_unlocked(ra, RA_STAT_DISTANT_READPAGE);
1155         } else if (!hit && ras->ras_window_len &&
1156                    index < ras->ras_next_readahead &&
1157                    index_in_window(index, ras->ras_window_start, 0,
1158                                    ras->ras_window_len)) {
1159                 zero = 1;
1160                 ll_ra_stats_inc_unlocked(ra, RA_STAT_MISS_IN_WINDOW);
1161         }
1162
1163         if (zero) {
1164                 ras_reset(ras, index);
1165                 GOTO(out_unlock, 0);
1166         }
1167
1168         ras->ras_last_readpage = index;
1169         ras->ras_consecutive++;
1170         ras_set_start(ras, index);
1171         ras->ras_next_readahead = max(ras->ras_window_start,
1172                                       ras->ras_next_readahead);
1173
1174         /* wait for a few pages to arrive before issuing readahead to avoid
1175          * the worst overutilization */
1176         if (ras->ras_consecutive == 3) {
1177                 ras->ras_window_len = PTLRPC_MAX_BRW_PAGES;
1178                 GOTO(out_unlock, 0);
1179         }
1180
1181         /* we need to increase the window sometimes.  we'll arbitrarily
1182          * do it half-way through the pages in an rpc */
1183         if ((index & (PTLRPC_MAX_BRW_PAGES - 1)) ==
1184             (PTLRPC_MAX_BRW_PAGES >> 1)) {
1185                 ras->ras_window_len += PTLRPC_MAX_BRW_PAGES;
1186                 ras->ras_window_len = min(ras->ras_window_len,
1187                                           ra->ra_max_pages);
1188         }
1189
1190         EXIT;
1191 out_unlock:
1192         RAS_CDEBUG(ras);
1193         spin_unlock(&ras->ras_lock);
1194         spin_unlock(&sbi->ll_lock);
1195         return;
1196 }
1197
1198 int ll_writepage(struct page *page)
1199 {
1200         struct inode *inode = page->mapping->host;
1201         struct ll_inode_info *lli = ll_i2info(inode);
1202         struct obd_export *exp;
1203         struct ll_async_page *llap;
1204         int rc = 0;
1205         ENTRY;
1206
1207         LASSERT(!PageDirty(page));
1208         LASSERT(PageLocked(page));
1209
1210         exp = ll_i2obdexp(inode);
1211         if (exp == NULL)
1212                 GOTO(out, rc = -EINVAL);
1213
1214         llap = llap_from_page(page, LLAP_ORIGIN_WRITEPAGE);
1215         if (IS_ERR(llap))
1216                 GOTO(out, rc = PTR_ERR(llap));
1217
1218         page_cache_get(page);
1219         if (llap->llap_write_queued) {
1220                 LL_CDEBUG_PAGE(D_PAGE, page, "marking urgent\n");
1221                 rc = obd_set_async_flags(exp, lli->lli_smd, NULL,
1222                                          llap->llap_cookie,
1223                                          ASYNC_READY | ASYNC_URGENT);
1224         } else {
1225                 rc = queue_or_sync_write(exp, inode, llap,
1226                                          PAGE_SIZE, ASYNC_READY | ASYNC_URGENT);
1227         }
1228         if (rc)
1229                 page_cache_release(page);
1230 out:
1231         if (rc) {
1232                 if (!lli->lli_async_rc)
1233                         lli->lli_async_rc = rc;
1234                 /* re-dirty page on error so it retries write */
1235                 ll_redirty_page(page);
1236                 unlock_page(page);
1237         }
1238         RETURN(rc);
1239 }
1240
1241 /*
1242  * for now we do our readpage the same on both 2.4 and 2.5.  The kernel's
1243  * read-ahead assumes it is valid to issue readpage all the way up to
1244  * i_size, but our dlm locks make that not the case.  We disable the
1245  * kernel's read-ahead and do our own by walking ahead in the page cache
1246  * checking for dlm lock coverage.  the main difference between 2.4 and
1247  * 2.6 is how read-ahead gets batched and issued, but we're using our own,
1248  * so they look the same.
1249  */
1250 int ll_readpage(struct file *filp, struct page *page)
1251 {
1252         struct ll_file_data *fd = LUSTRE_FPRIVATE(filp);
1253         struct inode *inode = page->mapping->host;
1254         struct obd_export *exp;
1255         struct ll_async_page *llap;
1256         struct obd_io_group *oig = NULL;
1257         int rc;
1258         ENTRY;
1259
1260         LASSERT(PageLocked(page));
1261         LASSERT(!PageUptodate(page));
1262         CDEBUG(D_VFSTRACE, "VFS Op:inode=%lu/%u(%p),offset=%Lu=%#Lx\n",
1263                inode->i_ino, inode->i_generation, inode,
1264                (((loff_t)page->index) << PAGE_SHIFT),
1265                (((loff_t)page->index) << PAGE_SHIFT));
1266         LASSERT(atomic_read(&filp->f_dentry->d_inode->i_count) > 0);
1267
1268         rc = oig_init(&oig);
1269         if (rc < 0)
1270                 GOTO(out, rc);
1271
1272         exp = ll_i2obdexp(inode);
1273         if (exp == NULL)
1274                 GOTO(out, rc = -EINVAL);
1275
1276         llap = llap_from_page(page, LLAP_ORIGIN_READPAGE);
1277         if (IS_ERR(llap))
1278                 GOTO(out, rc = PTR_ERR(llap));
1279
1280         if (ll_i2sbi(inode)->ll_ra_info.ra_max_pages)
1281                 ras_update(ll_i2sbi(inode), &fd->fd_ras, page->index,
1282                            llap->llap_defer_uptodate);
1283
1284         if (llap->llap_defer_uptodate) {
1285                 llap->llap_ra_used = 1;
1286                 rc = ll_readahead(&fd->fd_ras, exp, page->mapping, oig,
1287                                   fd->fd_flags);
1288                 if (rc > 0)
1289                         obd_trigger_group_io(exp, ll_i2info(inode)->lli_smd,
1290                                              NULL, oig);
1291                 LL_CDEBUG_PAGE(D_PAGE, page, "marking uptodate from defer\n");
1292                 SetPageUptodate(page);
1293                 unlock_page(page);
1294                 GOTO(out_oig, rc = 0);
1295         }
1296
1297         rc = ll_page_matches(page, 0);
1298         if (rc < 0) {
1299                 LL_CDEBUG_PAGE(D_ERROR, page, "lock match failed: rc %d\n", rc);
1300                 GOTO(out, rc);
1301         }
1302
1303         if (rc == 0) {
1304                 CWARN("ino %lu page %lu (%llu) not covered by "
1305                       "a lock (mmap?).  check debug logs.\n",
1306                       inode->i_ino, page->index,
1307                       (long long)page->index << PAGE_CACHE_SHIFT);
1308         }
1309
1310         rc = ll_issue_page_read(exp, llap, oig, 0);
1311         if (rc)
1312                 GOTO(out, rc);
1313
1314         LL_CDEBUG_PAGE(D_PAGE, page, "queued readpage\n");
1315         if (ll_i2sbi(inode)->ll_ra_info.ra_max_pages)
1316                 ll_readahead(&fd->fd_ras, exp, page->mapping, oig,
1317                              fd->fd_flags);
1318
1319         rc = obd_trigger_group_io(exp, ll_i2info(inode)->lli_smd, NULL, oig);
1320
1321 out:
1322         if (rc)
1323                 unlock_page(page);
1324 out_oig:
1325         if (oig != NULL)
1326                 oig_release(oig);
1327         RETURN(rc);
1328 }