lustre/llite/rw.c

   1 /*
   2  * OBDFS Super operations
   3  *
   4  * This code is issued under the GNU General Public License.
   5  * See the file COPYING in this distribution
   6  *
   7  * Copyright (C) 1996, 1997, Olaf Kirch <okir@monad.swb.de>
   8  * Copryright (C) 1999 Stelias Computing Inc,
   9  *                (author Peter J. Braam <braam@stelias.com>)
  10  * Copryright (C) 1999 Seagate Technology Inc.
  11 */
  12
  13
  14 #include <linux/config.h>
  15 #include <linux/kernel.h>
  16 #include <linux/mm.h>
  17 #include <linux/string.h>
  18 #include <linux/stat.h>
  19 #include <linux/errno.h>
  20 #include <linux/locks.h>
  21 #include <linux/unistd.h>
  22
  23 #include <asm/system.h>
  24 #include <asm/uaccess.h>
  25
  26 #include <linux/fs.h>
  27 #include <linux/stat.h>
  28 #include <asm/uaccess.h>
  29 #include <linux/vmalloc.h>
  30 #include <asm/segment.h>
  31 #include <linux/mm.h>
  32 #include <linux/pagemap.h>
  33 #include <linux/smp_lock.h>
  34
  35 #include <linux/obd_support.h>
  36 #include <linux/lustre_lib.h>
  37 #include <linux/lustre_idl.h>
  38 #include <linux/lustre_mds.h>
  39 #include <linux/lustre_light.h>
  40
  41 void ll_change_inode(struct inode *inode);
  42
  43 static int cache_writes = 0;
  44
  45
  46 /* page cache support stuff */
  47
  48
  49 /*
  50  * Add a page to the dirty page list.
  51  */
  52 void set_page_dirty(struct page *page)
  53 {
  54         if (!test_and_set_bit(PG_dirty, &page->flags)) {
  55                 struct address_space *mapping = page->mapping;
  56
  57                 if (mapping) {
  58                         spin_lock(&pagecache_lock);
  59                         list_del(&page->list);
  60                         list_add(&page->list, &mapping->dirty_pages);
  61                         spin_unlock(&pagecache_lock);
  62
  63                         if (mapping->host)
  64                                 mark_inode_dirty_pages(mapping->host);
  65                 }
  66         }
  67 }
  68
  69 /*
  70  * Remove page from dirty list
  71  */
  72 void __set_page_clean(struct page *page)
  73 {
  74         struct address_space *mapping = page->mapping;
  75         struct inode *inode;
  76
  77         if (!mapping)
  78                 return;
  79
  80         spin_lock(&pagecache_lock);
  81         list_del(&page->list);
  82         list_add(&page->list, &mapping->clean_pages);
  83
  84         inode = mapping->host;
  85         if (list_empty(&mapping->dirty_pages)) {
  86                 CDEBUG(D_INODE, "inode clean\n");
  87                 inode->i_state &= ~I_DIRTY_PAGES;
  88         }
  89         spin_unlock(&pagecache_lock);
  90         EXIT;
  91 }
  92
  93 inline void set_page_clean(struct page *page)
  94 {
  95         if (PageDirty(page)) {
  96                 ClearPageDirty(page);
  97                 __set_page_clean(page);
  98         }
  99 }
 100
 101 /* SYNCHRONOUS I/O to object storage for an inode -- object attr will be updated too */
 102 static int ll_brw(int rw, struct inode *inode, struct page *page, int create)
 103 {
 104         obd_count        num_obdo = 1;
 105         obd_count        bufs_per_obdo = 1;
 106         struct obdo     *oa;
 107         obd_size         count = PAGE_SIZE;
 108         obd_off          offset = ((obd_off)page->index) << PAGE_SHIFT;
 109         obd_flag         flags = create ? OBD_BRW_CREATE : 0;
 110         int              err;
 111
 112         ENTRY;
 113
 114         oa = obdo_alloc();
 115         if ( !oa ) {
 116                 EXIT;
 117                 return -ENOMEM;
 118         }
 119         oa->o_valid = OBD_MD_FLNOTOBD;
 120         ll_from_inode(oa, inode);
 121
 122         err = obd_brw(rw, IID(inode), num_obdo, &oa, &bufs_per_obdo,
 123                                &page, &count, &offset, &flags);
 124         //if ( !err )
 125         //      ll_to_inode(inode, oa); /* copy o_blocks to i_blocks */
 126
 127         obdo_free(oa);
 128         EXIT;
 129         return err;
 130 } /* ll_brw */
 131
 132 extern void set_page_clean(struct page *);
 133
 134 /* SYNCHRONOUS I/O to object storage for an inode -- object attr will be updated too */
 135 static int ll_commit_page(struct page *page, int create, int from, int to)
 136 {
 137         struct inode *inode = page->mapping->host;
 138         obd_count        num_obdo = 1;
 139         obd_count        bufs_per_obdo = 1;
 140         struct obdo     *oa;
 141         obd_size         count = to;
 142         obd_off          offset = (((obd_off)page->index) << PAGE_SHIFT);
 143         obd_flag         flags = create ? OBD_BRW_CREATE : 0;
 144         int              err;
 145
 146         ENTRY;
 147         oa = obdo_alloc();
 148         if ( !oa ) {
 149                 EXIT;
 150                 return -ENOMEM;
 151         }
 152         oa->o_valid = OBD_MD_FLNOTOBD;
 153         ll_from_inode(oa, inode);
 154
 155         CDEBUG(D_INODE, "commit_page writing (at %d) to %d, count %Ld\n",
 156                from, to, count);
 157
 158         err = obd_brw(WRITE, IID(inode), num_obdo, &oa, &bufs_per_obdo,
 159                                &page, &count, &offset, &flags);
 160         if ( !err ) {
 161                 SetPageUptodate(page);
 162                 set_page_clean(page);
 163         }
 164
 165         //if ( !err )
 166         //      ll_to_inode(inode, oa); /* copy o_blocks to i_blocks */
 167
 168         obdo_free(oa);
 169         EXIT;
 170         return err;
 171 } /* ll_brw */
 172
 173
 174 /* returns the page unlocked, but with a reference */
 175 int ll_readpage(struct file *file, struct page *page)
 176 {
 177         struct inode *inode = page->mapping->host;
 178         int rc;
 179
 180         ENTRY;
 181
 182         if ( ((inode->i_size + PAGE_CACHE_SIZE -1)>>PAGE_SHIFT)
 183              <= page->index) {
 184                 memset(kmap(page), 0, PAGE_CACHE_SIZE);
 185                 kunmap(page);
 186                 goto readpage_out;
 187         }
 188
 189         if (Page_Uptodate(page)) {
 190                 EXIT;
 191                 goto readpage_out;
 192         }
 193
 194         rc = ll_brw(READ, inode, page, 0);
 195         if ( rc ) {
 196                 EXIT;
 197                 return rc;
 198         }
 199         /* PDEBUG(page, "READ"); */
 200
 201  readpage_out:
 202         SetPageUptodate(page);
 203         obd_unlock_page(page);
 204         EXIT;
 205         return 0;
 206 } /* ll_readpage */
 207
 208
 209
 210 /* returns the page unlocked, but with a reference */
 211 int ll_dir_readpage(struct file *file, struct page *page)
 212 {
 213         struct inode *inode = page->mapping->host;
 214         char *buf;
 215         __u64 offset;
 216         int rc = 0;
 217         struct mds_rep_hdr *hdr;
 218
 219         ENTRY;
 220
 221         if ( ((inode->i_size + PAGE_CACHE_SIZE -1)>>PAGE_SHIFT)
 222              <= page->index) {
 223                 memset(kmap(page), 0, PAGE_CACHE_SIZE);
 224                 kunmap(page);
 225                 goto readpage_out;
 226         }
 227
 228         if (Page_Uptodate(page)) {
 229                 EXIT;
 230                 goto readpage_out;
 231         }
 232
 233         offset = page->index << PAGE_SHIFT;
 234         buf = kmap(page);
 235         rc = mdc_readpage(inode->i_ino, S_IFDIR, offset, buf, NULL, &hdr);
 236         kunmap(buff);
 237         if ( rc ) {
 238                 EXIT;
 239                 goto readpage_out;
 240         }
 241
 242         if ((rc = hdr->status)) {
 243                 EXIT;
 244                 goto readpage_out;
 245         }
 246
 247         /* PDEBUG(page, "READ"); */
 248
 249         SetPageUptodate(page);
 250  readpage_out:
 251         unlock_page(page);
 252         EXIT;
 253         return rc;
 254 } /* ll_dir_readpage */
 255
 256 int ll_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to)
 257 {
 258         struct inode *inode = page->mapping->host;
 259         obd_off offset = ((obd_off)page->index) << PAGE_SHIFT;
 260         int rc = 0;
 261         ENTRY;
 262
 263         kmap(page);
 264         if (Page_Uptodate(page)) {
 265                 EXIT;
 266                 goto prepare_done;
 267         }
 268
 269         if ( (from <= offset) && (to >= offset + PAGE_SIZE) ) {
 270                 EXIT;
 271                 return 0;
 272         }
 273
 274         rc = ll_brw(READ, inode, page, 0);
 275         if ( !rc ) {
 276                 SetPageUptodate(page);
 277         }
 278
 279  prepare_done:
 280         set_page_dirty(page);
 281         //SetPageDirty(page);
 282         EXIT;
 283         return rc;
 284 }
 285
 286
 287
 288
 289
 290
 291 static kmem_cache_t *ll_pgrq_cachep = NULL;
 292
 293 int ll_init_pgrqcache(void)
 294 {
 295         ENTRY;
 296         if (ll_pgrq_cachep == NULL) {
 297                 CDEBUG(D_CACHE, "allocating ll_pgrq_cache\n");
 298                 ll_pgrq_cachep = kmem_cache_create("ll_pgrq",
 299                                                       sizeof(struct ll_pgrq),
 300                                                       0, SLAB_HWCACHE_ALIGN,
 301                                                       NULL, NULL);
 302                 if (ll_pgrq_cachep == NULL) {
 303                         EXIT;
 304                         return -ENOMEM;
 305                 } else {
 306                         CDEBUG(D_CACHE, "allocated cache at %p\n",
 307                                ll_pgrq_cachep);
 308                 }
 309         } else {
 310                 CDEBUG(D_CACHE, "using existing cache at %p\n",
 311                        ll_pgrq_cachep);
 312         }
 313         EXIT;
 314         return 0;
 315 } /* ll_init_wreqcache */
 316
 317 inline void ll_pgrq_del(struct ll_pgrq *pgrq)
 318 {
 319         --ll_cache_count;
 320         CDEBUG(D_INFO, "deleting page %p from list [count %ld]\n",
 321                pgrq->rq_page, ll_cache_count);
 322         list_del(&pgrq->rq_plist);
 323         OBDClearCachePage(pgrq->rq_page);
 324         kmem_cache_free(ll_pgrq_cachep, pgrq);
 325 }
 326
 327 void ll_cleanup_pgrqcache(void)
 328 {
 329         ENTRY;
 330         if (ll_pgrq_cachep != NULL) {
 331                 CDEBUG(D_CACHE, "destroying ll_pgrqcache at %p, count %ld\n",
 332                        ll_pgrq_cachep, ll_cache_count);
 333                 if (kmem_cache_destroy(ll_pgrq_cachep))
 334                         printk(KERN_INFO __FUNCTION__
 335                                ": unable to free all of cache\n");
 336                 ll_pgrq_cachep = NULL;
 337         } else
 338                 printk(KERN_INFO __FUNCTION__ ": called with NULL pointer\n");
 339
 340         EXIT;
 341 } /* ll_cleanup_wreqcache */
 342
 343
 344 /* called with the list lock held */
 345 static struct page *ll_find_page_index(struct inode *inode,
 346                                           unsigned long index)
 347 {
 348         struct list_head *page_list = ll_iplist(inode);
 349         struct list_head *tmp;
 350         struct page *page;
 351
 352         ENTRY;
 353
 354         CDEBUG(D_INFO, "looking for inode %ld pageindex %ld\n",
 355                inode->i_ino, index);
 356         OIDEBUG(inode);
 357
 358         if (list_empty(page_list)) {
 359                 EXIT;
 360                 return NULL;
 361         }
 362         tmp = page_list;
 363         while ( (tmp = tmp->next) != page_list ) {
 364                 struct ll_pgrq *pgrq;
 365
 366                 pgrq = list_entry(tmp, struct ll_pgrq, rq_plist);
 367                 page = pgrq->rq_page;
 368                 if (index == page->index) {
 369                         CDEBUG(D_INFO,
 370                                "INDEX SEARCH found page %p, index %ld\n",
 371                                page, index);
 372                         EXIT;
 373                         return page;
 374                 }
 375         }
 376
 377         EXIT;
 378         return NULL;
 379 } /* ll_find_page_index */
 380
 381
 382 /* call and free pages from Linux page cache: called with io lock on inodes */
 383 int ll_do_vec_wr(struct inode **inodes, obd_count num_io,
 384                     obd_count num_obdos, struct obdo **obdos,
 385                     obd_count *oa_bufs, struct page **pages, char **bufs,
 386                     obd_size *counts, obd_off *offsets, obd_flag *flags)
 387 {
 388         int err;
 389
 390         ENTRY;
 391
 392         CDEBUG(D_INFO, "writing %d page(s), %d obdo(s) in vector\n",
 393                num_io, num_obdos);
 394         if (obd_debug_level & D_INFO) { /* DEBUGGING */
 395                 int i;
 396                 printk("OBDOS: ");
 397                 for (i = 0; i < num_obdos; i++)
 398                         printk("%ld:0x%p ", (long)obdos[i]->o_id, obdos[i]);
 399
 400                 printk("\nPAGES: ");
 401                 for (i = 0; i < num_io; i++)
 402                         printk("0x%p ", pages[i]);
 403                 printk("\n");
 404         }
 405
 406         err = obd_brw(WRITE, IID(inodes[0]), num_obdos, obdos,
 407                                   oa_bufs, pages, counts, offsets, flags);
 408
 409         CDEBUG(D_INFO, "BRW done\n");
 410         /* release the pages from the page cache */
 411         while ( num_io > 0 ) {
 412                 --num_io;
 413                 CDEBUG(D_INFO, "calling put_page for %p, index %ld\n",
 414                        pages[num_io], pages[num_io]->index);
 415                 /* PDEBUG(pages[num_io], "do_vec_wr"); */
 416                 put_page(pages[num_io]);
 417                 /* PDEBUG(pages[num_io], "do_vec_wr"); */
 418         }
 419         CDEBUG(D_INFO, "put_page done\n");
 420
 421         while ( num_obdos > 0) {
 422                 --num_obdos;
 423                 CDEBUG(D_INFO, "free obdo %ld\n",(long)obdos[num_obdos]->o_id);
 424                 /* copy o_blocks to i_blocks */
 425                 ll_set_size (inodes[num_obdos], obdos[num_obdos]->o_size);
 426                 //ll_to_inode(inodes[num_obdos], obdos[num_obdos]);
 427                 obdo_free(obdos[num_obdos]);
 428         }
 429         CDEBUG(D_INFO, "obdo_free done\n");
 430         EXIT;
 431         return err;
 432 }
 433
 434
 435 /*
 436  * Add a page to the write request cache list for later writing.
 437  * ASYNCHRONOUS write method.
 438  */
 439 static int ll_add_page_to_cache(struct inode *inode, struct page *page)
 440 {
 441         int err = 0;
 442         ENTRY;
 443
 444         /* The PG_obdcache bit is cleared by ll_pgrq_del() BEFORE the page
 445          * is written, so at worst we will write the page out twice.
 446          *
 447          * If the page has the PG_obdcache bit set, then the inode MUST be
 448          * on the superblock dirty list so we don't need to check this.
 449          * Dirty inodes are removed from the superblock list ONLY when they
 450          * don't have any more cached pages.  It is possible to have an inode
 451          * with no dirty pages on the superblock list, but not possible to
 452          * have an inode with dirty pages NOT on the superblock dirty list.
 453          */
 454         if (!OBDAddCachePage(page)) {
 455                 struct ll_pgrq *pgrq;
 456                 pgrq = kmem_cache_alloc(ll_pgrq_cachep, SLAB_KERNEL);
 457                 if (!pgrq) {
 458                         OBDClearCachePage(page);
 459                         EXIT;
 460                         return -ENOMEM;
 461                 }
 462                 /* not really necessary since we set all pgrq fields here
 463                 memset(pgrq, 0, sizeof(*pgrq));
 464                 */
 465
 466                 pgrq->rq_page = page;
 467                 pgrq->rq_jiffies = jiffies;
 468                 get_page(pgrq->rq_page);
 469
 470                 obd_down(&ll_i2sbi(inode)->ll_list_mutex);
 471                 list_add(&pgrq->rq_plist, ll_iplist(inode));
 472                 ll_cache_count++;
 473                 //printk("-- count %d\n", ll_cache_count);
 474
 475                 /* If inode isn't already on superblock inodes list, add it.
 476                  *
 477                  * We increment the reference count on the inode to keep it
 478                  * from being freed from memory.  This _should_ be an iget()
 479                  * with an iput() in both flush_reqs() and put_inode(), but
 480                  * since put_inode() is called from iput() we can't call iput()
 481                  * again there.  Instead we just increment/decrement i_count,
 482                  * which is mostly what iget/iput do for an inode in memory.
 483                  */
 484                 if ( list_empty(ll_islist(inode)) ) {
 485                         atomic_inc(&inode->i_count);
 486                         CDEBUG(D_INFO,
 487                                "adding inode %ld to superblock list %p\n",
 488                                inode->i_ino, ll_slist(inode));
 489                         list_add(ll_islist(inode), ll_slist(inode));
 490                 }
 491                 obd_up(&ll_i2sbi(inode)->ll_list_mutex);
 492
 493         }
 494
 495         /* XXX For testing purposes, we can write out the page here.
 496         err = ll_flush_reqs(ll_slist(inode), ~0UL);
 497          */
 498
 499         EXIT;
 500         return err;
 501 } /* ll_add_page_to_cache */
 502
 503 void rebalance(void)
 504 {
 505         if (ll_cache_count > 60000) {
 506                 printk("-- count %ld\n", ll_cache_count);
 507                 //ll_flush_dirty_pages(~0UL);
 508                 printk("-- count %ld\n", ll_cache_count);
 509         }
 510 }
 511
 512 /* select between SYNC and ASYNC I/O methods */
 513 int ll_do_writepage(struct page *page, int sync)
 514 {
 515         struct inode *inode = page->mapping->host;
 516         int err;
 517
 518         ENTRY;
 519         /* PDEBUG(page, "WRITEPAGE"); */
 520         if ( sync )
 521                 err = ll_brw(WRITE, inode, page, 1);
 522         else {
 523                 err = ll_add_page_to_cache(inode, page);
 524                 CDEBUG(D_INFO, "DO_WR ino: %ld, page %p, err %d, uptodate %d\n",
 525                        inode->i_ino, page, err, Page_Uptodate(page));
 526         }
 527
 528         if ( !err ) {
 529                 SetPageUptodate(page);
 530                 set_page_clean(page);
 531         }
 532         /* PDEBUG(page,"WRITEPAGE"); */
 533         EXIT;
 534         return err;
 535 } /* ll_do_writepage */
 536
 537
 538
 539 /* returns the page unlocked, but with a reference */
 540 int ll_writepage(struct page *page)
 541 {
 542         int rc;
 543         struct inode *inode = page->mapping->host;
 544         ENTRY;
 545         printk("---> writepage called ino %ld!\n", inode->i_ino);
 546         BUG();
 547         rc = ll_do_writepage(page, 1);
 548         if ( !rc ) {
 549                 set_page_clean(page);
 550         } else {
 551                 CDEBUG(D_INODE, "--> GRR %d\n", rc);
 552         }
 553         EXIT;
 554         return rc;
 555 }
 556
 557 void write_inode_pages(struct inode *inode)
 558 {
 559         struct list_head *tmp = &inode->i_mapping->dirty_pages;
 560
 561         while ( (tmp = tmp->next) != &inode->i_mapping->dirty_pages) {
 562                 struct page *page;
 563                 page = list_entry(tmp, struct page, list);
 564                 ll_writepage(page);
 565         }
 566 }
 567
 568
 569 int ll_commit_write(struct file *file, struct page *page, unsigned from, unsigned to)
 570 {
 571         struct inode *inode = page->mapping->host;
 572         int rc = 0;
 573         loff_t len = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
 574         ENTRY;
 575         CDEBUG(D_INODE, "commit write ino %ld (end at %Ld) from %d to %d ,ind %ld\n",
 576                inode->i_ino, len, from, to, page->index);
 577
 578
 579         if (cache_writes == 0) {
 580                 rc = ll_commit_page(page, 1, from, to);
 581         }
 582
 583         if (len > inode->i_size) {
 584                 ll_set_size(inode, len);
 585         }
 586
 587         kunmap(page);
 588         EXIT;
 589         return rc;
 590 }
 591
 592
 593 /*
 594  * This does the "real" work of the write. The generic routine has
 595  * allocated the page, locked it, done all the page alignment stuff
 596  * calculations etc. Now we should just copy the data from user
 597  * space and write it back to the real medium..
 598  *
 599  * If the writer ends up delaying the write, the writer needs to
 600  * increment the page use counts until he is done with the page.
 601  *
 602  * Return value is the number of bytes written.
 603  */
 604 int ll_write_one_page(struct file *file, struct page *page,
 605                          unsigned long offset, unsigned long bytes,
 606                          const char * buf)
 607 {
 608         struct inode *inode = file->f_dentry->d_inode;
 609         int err;
 610
 611         ENTRY;
 612         /* We check for complete page writes here, as we then don't have to
 613          * get the page before writing over everything anyways.
 614          */
 615         if ( !Page_Uptodate(page) && (offset != 0 || bytes != PAGE_SIZE) ) {
 616                 err = ll_brw(READ, inode, page, 0);
 617                 if ( err )
 618                         return err;
 619                 SetPageUptodate(page);
 620         }
 621
 622         if (copy_from_user((u8*)page_address(page) + offset, buf, bytes))
 623                 return -EFAULT;
 624
 625         lock_kernel();
 626         err = ll_writepage(page);
 627         unlock_kernel();
 628
 629         return (err < 0 ? err : bytes);
 630 } /* ll_write_one_page */
 631
 632 /*
 633  * return an up to date page:
 634  *  - if locked is true then is returned locked
 635  *  - if create is true the corresponding disk blocks are created
 636  *  - page is held, i.e. caller must release the page
 637  *
 638  * modeled on NFS code.
 639  */
 640 struct page *ll_getpage(struct inode *inode, unsigned long offset,
 641                            int create, int locked)
 642 {
 643         struct page * page;
 644         int index;
 645         int err;
 646
 647         ENTRY;
 648
 649         offset = offset & PAGE_CACHE_MASK;
 650         CDEBUG(D_INFO, "ino: %ld, offset %ld, create %d, locked %d\n",
 651                inode->i_ino, offset, create, locked);
 652         index = offset >> PAGE_CACHE_SHIFT;
 653
 654         page = grab_cache_page(&inode->i_data, index);
 655
 656         /* Yuck, no page */
 657         if (! page) {
 658             printk(KERN_WARNING " grab_cache_page says no dice ...\n");
 659             EXIT;
 660             return NULL;
 661         }
 662
 663         /* PDEBUG(page, "GETPAGE: got page - before reading\n"); */
 664         /* now check if the data in the page is up to date */
 665         if ( Page_Uptodate(page)) {
 666                 if (!locked) {
 667                         if (PageLocked(page))
 668                                 obd_unlock_page(page);
 669                 } else {
 670                         printk("file %s, line %d: expecting locked page\n",
 671                                __FILE__, __LINE__);
 672                 }
 673                 EXIT;
 674                 return page;
 675         }
 676
 677
 678 #ifdef EXT2_OBD_DEBUG
 679         if ((obd_debug_level & D_INFO) && ll_find_page_index(inode, index)) {
 680                 CDEBUG(D_INFO, "OVERWRITE: found dirty page %p, index %ld\n",
 681                        page, page->index);
 682         }
 683 #endif
 684
 685         err = ll_brw(READ, inode, page, create);
 686
 687         if ( err ) {
 688                 SetPageError(page);
 689                 obd_unlock_page(page);
 690                 EXIT;
 691                 return page;
 692         }
 693
 694         if ( !locked )
 695                 obd_unlock_page(page);
 696         SetPageUptodate(page);
 697         /* PDEBUG(page,"GETPAGE - after reading"); */
 698         EXIT;
 699         return page;
 700 } /* ll_getpage */
 701
 702
 703 void ll_truncate(struct inode *inode)
 704 {
 705         struct obdo *oa;
 706         int err;
 707         ENTRY;
 708
 709         //ll_dequeue_pages(inode);
 710
 711         oa = obdo_alloc();
 712         if ( !oa ) {
 713                 /* XXX This would give an inconsistent FS, so deal with it as
 714                  * best we can for now - an obdo on the stack is not pretty.
 715                  */
 716                 struct obdo obdo;
 717
 718                 printk(__FUNCTION__ ": obdo_alloc failed - using stack!\n");
 719
 720                 obdo.o_valid = OBD_MD_FLNOTOBD;
 721                 ll_from_inode(&obdo, inode);
 722
 723                 err = obd_punch(IID(inode), &obdo, 0, obdo.o_size);
 724         } else {
 725                 oa->o_valid = OBD_MD_FLNOTOBD;
 726                 ll_from_inode(oa, inode);
 727
 728                 CDEBUG(D_INFO, "calling punch for %ld (%Lu bytes at 0)\n",
 729                        (long)oa->o_id, oa->o_size);
 730                 err = obd_punch(IID(inode), oa, oa->o_size, 0);
 731
 732                 obdo_free(oa);
 733         }
 734
 735         if (err) {
 736                 printk(__FUNCTION__ ": obd_truncate fails (%d)\n", err);
 737                 EXIT;
 738                 return;
 739         }
 740         EXIT;
 741 } /* ll_truncate */
 742
 743 struct address_space_operations ll_aops = {
 744         readpage: ll_readpage,
 745         writepage: ll_writepage,
 746         sync_page: block_sync_page,
 747         prepare_write: ll_prepare_write,
 748         commit_write: ll_commit_write,
 749         bmap: NULL
 750 };
 751
 752
 753 struct address_space_operations ll_dir_aops = {
 754         readpage: ll_dir_readpage
 755 };