fs/afs/write.c

   1 /* handling of writes to regular files and writing back to the server
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/backing-dev.h>
  13 #include <linux/slab.h>
  14 #include <linux/fs.h>
  15 #include <linux/pagemap.h>
  16 #include <linux/writeback.h>
  17 #include <linux/pagevec.h>
  18 #include "internal.h"
  19
  20 /*
  21  * mark a page as having been made dirty and thus needing writeback
  22  */
  23 int afs_set_page_dirty(struct page *page)
  24 {
  25         _enter("");
  26         return __set_page_dirty_nobuffers(page);
  27 }
  28
  29 /*
  30  * partly or wholly fill a page that's under preparation for writing
  31  */
  32 static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
  33                          loff_t pos, unsigned int len, struct page *page)
  34 {
  35         struct afs_read *req;
  36         int ret;
  37
  38         _enter(",,%llu", (unsigned long long)pos);
  39
  40         req = kzalloc(sizeof(struct afs_read) + sizeof(struct page *),
  41                       GFP_KERNEL);
  42         if (!req)
  43                 return -ENOMEM;
  44
  45         atomic_set(&req->usage, 1);
  46         req->pos = pos;
  47         req->len = len;
  48         req->nr_pages = 1;
  49         req->pages[0] = page;
  50         get_page(page);
  51
  52         ret = afs_fetch_data(vnode, key, req);
  53         afs_put_read(req);
  54         if (ret < 0) {
  55                 if (ret == -ENOENT) {
  56                         _debug("got NOENT from server"
  57                                " - marking file deleted and stale");
  58                         set_bit(AFS_VNODE_DELETED, &vnode->flags);
  59                         ret = -ESTALE;
  60                 }
  61         }
  62
  63         _leave(" = %d", ret);
  64         return ret;
  65 }
  66
  67 /*
  68  * prepare to perform part of a write to a page
  69  */
  70 int afs_write_begin(struct file *file, struct address_space *mapping,
  71                     loff_t pos, unsigned len, unsigned flags,
  72                     struct page **pagep, void **fsdata)
  73 {
  74         struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
  75         struct page *page;
  76         struct key *key = afs_file_key(file);
  77         unsigned long priv;
  78         unsigned f, from = pos & (PAGE_SIZE - 1);
  79         unsigned t, to = from + len;
  80         pgoff_t index = pos >> PAGE_SHIFT;
  81         int ret;
  82
  83         _enter("{%x:%u},{%lx},%u,%u",
  84                vnode->fid.vid, vnode->fid.vnode, index, from, to);
  85
  86         /* We want to store information about how much of a page is altered in
  87          * page->private.
  88          */
  89         BUILD_BUG_ON(PAGE_SIZE > 32768 && sizeof(page->private) < 8);
  90
  91         page = grab_cache_page_write_begin(mapping, index, flags);
  92         if (!page)
  93                 return -ENOMEM;
  94
  95         if (!PageUptodate(page) && len != PAGE_SIZE) {
  96                 ret = afs_fill_page(vnode, key, pos & PAGE_MASK, PAGE_SIZE, page);
  97                 if (ret < 0) {
  98                         unlock_page(page);
  99                         put_page(page);
 100                         _leave(" = %d [prep]", ret);
 101                         return ret;
 102                 }
 103                 SetPageUptodate(page);
 104         }
 105
 106         /* page won't leak in error case: it eventually gets cleaned off LRU */
 107         *pagep = page;
 108
 109 try_again:
 110         /* See if this page is already partially written in a way that we can
 111          * merge the new write with.
 112          */
 113         t = f = 0;
 114         if (PagePrivate(page)) {
 115                 priv = page_private(page);
 116                 f = priv & AFS_PRIV_MAX;
 117                 t = priv >> AFS_PRIV_SHIFT;
 118                 ASSERTCMP(f, <=, t);
 119         }
 120
 121         if (f != t) {
 122                 if (PageWriteback(page)) {
 123                         trace_afs_page_dirty(vnode, tracepoint_string("alrdy"),
 124                                              page->index, priv);
 125                         goto flush_conflicting_write;
 126                 }
 127                 if (to < f || from > t)
 128                         goto flush_conflicting_write;
 129                 if (from < f)
 130                         f = from;
 131                 if (to > t)
 132                         t = to;
 133         } else {
 134                 f = from;
 135                 t = to;
 136         }
 137
 138         priv = (unsigned long)t << AFS_PRIV_SHIFT;
 139         priv |= f;
 140         trace_afs_page_dirty(vnode, tracepoint_string("begin"),
 141                              page->index, priv);
 142         SetPagePrivate(page);
 143         set_page_private(page, priv);
 144         _leave(" = 0");
 145         return 0;
 146
 147         /* The previous write and this write aren't adjacent or overlapping, so
 148          * flush the page out.
 149          */
 150 flush_conflicting_write:
 151         _debug("flush conflict");
 152         ret = write_one_page(page);
 153         if (ret < 0) {
 154                 _leave(" = %d", ret);
 155                 return ret;
 156         }
 157
 158         ret = lock_page_killable(page);
 159         if (ret < 0) {
 160                 _leave(" = %d", ret);
 161                 return ret;
 162         }
 163         goto try_again;
 164 }
 165
 166 /*
 167  * finalise part of a write to a page
 168  */
 169 int afs_write_end(struct file *file, struct address_space *mapping,
 170                   loff_t pos, unsigned len, unsigned copied,
 171                   struct page *page, void *fsdata)
 172 {
 173         struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
 174         struct key *key = afs_file_key(file);
 175         loff_t i_size, maybe_i_size;
 176         int ret;
 177
 178         _enter("{%x:%u},{%lx}",
 179                vnode->fid.vid, vnode->fid.vnode, page->index);
 180
 181         maybe_i_size = pos + copied;
 182
 183         i_size = i_size_read(&vnode->vfs_inode);
 184         if (maybe_i_size > i_size) {
 185                 spin_lock(&vnode->wb_lock);
 186                 i_size = i_size_read(&vnode->vfs_inode);
 187                 if (maybe_i_size > i_size)
 188                         i_size_write(&vnode->vfs_inode, maybe_i_size);
 189                 spin_unlock(&vnode->wb_lock);
 190         }
 191
 192         if (!PageUptodate(page)) {
 193                 if (copied < len) {
 194                         /* Try and load any missing data from the server.  The
 195                          * unmarshalling routine will take care of clearing any
 196                          * bits that are beyond the EOF.
 197                          */
 198                         ret = afs_fill_page(vnode, key, pos + copied,
 199                                             len - copied, page);
 200                         if (ret < 0)
 201                                 goto out;
 202                 }
 203                 SetPageUptodate(page);
 204         }
 205
 206         set_page_dirty(page);
 207         if (PageDirty(page))
 208                 _debug("dirtied");
 209         ret = copied;
 210
 211 out:
 212         unlock_page(page);
 213         put_page(page);
 214         return ret;
 215 }
 216
 217 /*
 218  * kill all the pages in the given range
 219  */
 220 static void afs_kill_pages(struct address_space *mapping,
 221                            pgoff_t first, pgoff_t last)
 222 {
 223         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 224         struct pagevec pv;
 225         unsigned count, loop;
 226
 227         _enter("{%x:%u},%lx-%lx",
 228                vnode->fid.vid, vnode->fid.vnode, first, last);
 229
 230         pagevec_init(&pv);
 231
 232         do {
 233                 _debug("kill %lx-%lx", first, last);
 234
 235                 count = last - first + 1;
 236                 if (count > PAGEVEC_SIZE)
 237                         count = PAGEVEC_SIZE;
 238                 pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
 239                 ASSERTCMP(pv.nr, ==, count);
 240
 241                 for (loop = 0; loop < count; loop++) {
 242                         struct page *page = pv.pages[loop];
 243                         ClearPageUptodate(page);
 244                         SetPageError(page);
 245                         end_page_writeback(page);
 246                         if (page->index >= first)
 247                                 first = page->index + 1;
 248                         lock_page(page);
 249                         generic_error_remove_page(mapping, page);
 250                 }
 251
 252                 __pagevec_release(&pv);
 253         } while (first <= last);
 254
 255         _leave("");
 256 }
 257
 258 /*
 259  * Redirty all the pages in a given range.
 260  */
 261 static void afs_redirty_pages(struct writeback_control *wbc,
 262                               struct address_space *mapping,
 263                               pgoff_t first, pgoff_t last)
 264 {
 265         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 266         struct pagevec pv;
 267         unsigned count, loop;
 268
 269         _enter("{%x:%u},%lx-%lx",
 270                vnode->fid.vid, vnode->fid.vnode, first, last);
 271
 272         pagevec_init(&pv);
 273
 274         do {
 275                 _debug("redirty %lx-%lx", first, last);
 276
 277                 count = last - first + 1;
 278                 if (count > PAGEVEC_SIZE)
 279                         count = PAGEVEC_SIZE;
 280                 pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
 281                 ASSERTCMP(pv.nr, ==, count);
 282
 283                 for (loop = 0; loop < count; loop++) {
 284                         struct page *page = pv.pages[loop];
 285
 286                         redirty_page_for_writepage(wbc, page);
 287                         end_page_writeback(page);
 288                         if (page->index >= first)
 289                                 first = page->index + 1;
 290                 }
 291
 292                 __pagevec_release(&pv);
 293         } while (first <= last);
 294
 295         _leave("");
 296 }
 297
 298 /*
 299  * write to a file
 300  */
 301 static int afs_store_data(struct address_space *mapping,
 302                           pgoff_t first, pgoff_t last,
 303                           unsigned offset, unsigned to)
 304 {
 305         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 306         struct afs_fs_cursor fc;
 307         struct afs_wb_key *wbk = NULL;
 308         struct list_head *p;
 309         int ret = -ENOKEY, ret2;
 310
 311         _enter("%s{%x:%u.%u},%lx,%lx,%x,%x",
 312                vnode->volume->name,
 313                vnode->fid.vid,
 314                vnode->fid.vnode,
 315                vnode->fid.unique,
 316                first, last, offset, to);
 317
 318         spin_lock(&vnode->wb_lock);
 319         p = vnode->wb_keys.next;
 320
 321         /* Iterate through the list looking for a valid key to use. */
 322 try_next_key:
 323         while (p != &vnode->wb_keys) {
 324                 wbk = list_entry(p, struct afs_wb_key, vnode_link);
 325                 _debug("wbk %u", key_serial(wbk->key));
 326                 ret2 = key_validate(wbk->key);
 327                 if (ret2 == 0)
 328                         goto found_key;
 329                 if (ret == -ENOKEY)
 330                         ret = ret2;
 331                 p = p->next;
 332         }
 333
 334         spin_unlock(&vnode->wb_lock);
 335         afs_put_wb_key(wbk);
 336         _leave(" = %d [no keys]", ret);
 337         return ret;
 338
 339 found_key:
 340         refcount_inc(&wbk->usage);
 341         spin_unlock(&vnode->wb_lock);
 342
 343         _debug("USE WB KEY %u", key_serial(wbk->key));
 344
 345         ret = -ERESTARTSYS;
 346         if (afs_begin_vnode_operation(&fc, vnode, wbk->key)) {
 347                 while (afs_select_fileserver(&fc)) {
 348                         fc.cb_break = vnode->cb_break + vnode->cb_s_break;
 349                         afs_fs_store_data(&fc, mapping, first, last, offset, to);
 350                 }
 351
 352                 afs_check_for_remote_deletion(&fc, fc.vnode);
 353                 afs_vnode_commit_status(&fc, vnode, fc.cb_break);
 354                 ret = afs_end_vnode_operation(&fc);
 355         }
 356
 357         switch (ret) {
 358         case -EACCES:
 359         case -EPERM:
 360         case -ENOKEY:
 361         case -EKEYEXPIRED:
 362         case -EKEYREJECTED:
 363         case -EKEYREVOKED:
 364                 _debug("next");
 365                 spin_lock(&vnode->wb_lock);
 366                 p = wbk->vnode_link.next;
 367                 afs_put_wb_key(wbk);
 368                 goto try_next_key;
 369         }
 370
 371         afs_put_wb_key(wbk);
 372         _leave(" = %d", ret);
 373         return ret;
 374 }
 375
 376 /*
 377  * Synchronously write back the locked page and any subsequent non-locked dirty
 378  * pages.
 379  */
 380 static int afs_write_back_from_locked_page(struct address_space *mapping,
 381                                            struct writeback_control *wbc,
 382                                            struct page *primary_page,
 383                                            pgoff_t final_page)
 384 {
 385         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 386         struct page *pages[8], *page;
 387         unsigned long count, priv;
 388         unsigned n, offset, to, f, t;
 389         pgoff_t start, first, last;
 390         int loop, ret;
 391
 392         _enter(",%lx", primary_page->index);
 393
 394         count = 1;
 395         if (test_set_page_writeback(primary_page))
 396                 BUG();
 397
 398         /* Find all consecutive lockable dirty pages that have contiguous
 399          * written regions, stopping when we find a page that is not
 400          * immediately lockable, is not dirty or is missing, or we reach the
 401          * end of the range.
 402          */
 403         start = primary_page->index;
 404         priv = page_private(primary_page);
 405         offset = priv & AFS_PRIV_MAX;
 406         to = priv >> AFS_PRIV_SHIFT;
 407         trace_afs_page_dirty(vnode, tracepoint_string("store"),
 408                              primary_page->index, priv);
 409
 410         WARN_ON(offset == to);
 411         if (offset == to)
 412                 trace_afs_page_dirty(vnode, tracepoint_string("WARN"),
 413                                      primary_page->index, priv);
 414
 415         if (start >= final_page || to < PAGE_SIZE)
 416                 goto no_more;
 417
 418         start++;
 419         do {
 420                 _debug("more %lx [%lx]", start, count);
 421                 n = final_page - start + 1;
 422                 if (n > ARRAY_SIZE(pages))
 423                         n = ARRAY_SIZE(pages);
 424                 n = find_get_pages_contig(mapping, start, ARRAY_SIZE(pages), pages);
 425                 _debug("fgpc %u", n);
 426                 if (n == 0)
 427                         goto no_more;
 428                 if (pages[0]->index != start) {
 429                         do {
 430                                 put_page(pages[--n]);
 431                         } while (n > 0);
 432                         goto no_more;
 433                 }
 434
 435                 for (loop = 0; loop < n; loop++) {
 436                         if (to != PAGE_SIZE)
 437                                 break;
 438                         page = pages[loop];
 439                         if (page->index > final_page)
 440                                 break;
 441                         if (!trylock_page(page))
 442                                 break;
 443                         if (!PageDirty(page) || PageWriteback(page)) {
 444                                 unlock_page(page);
 445                                 break;
 446                         }
 447
 448                         priv = page_private(page);
 449                         f = priv & AFS_PRIV_MAX;
 450                         t = priv >> AFS_PRIV_SHIFT;
 451                         if (f != 0) {
 452                                 unlock_page(page);
 453                                 break;
 454                         }
 455                         to = t;
 456
 457                         trace_afs_page_dirty(vnode, tracepoint_string("store+"),
 458                                              page->index, priv);
 459
 460                         if (!clear_page_dirty_for_io(page))
 461                                 BUG();
 462                         if (test_set_page_writeback(page))
 463                                 BUG();
 464                         unlock_page(page);
 465                         put_page(page);
 466                 }
 467                 count += loop;
 468                 if (loop < n) {
 469                         for (; loop < n; loop++)
 470                                 put_page(pages[loop]);
 471                         goto no_more;
 472                 }
 473
 474                 start += loop;
 475         } while (start <= final_page && count < 65536);
 476
 477 no_more:
 478         /* We now have a contiguous set of dirty pages, each with writeback
 479          * set; the first page is still locked at this point, but all the rest
 480          * have been unlocked.
 481          */
 482         unlock_page(primary_page);
 483
 484         first = primary_page->index;
 485         last = first + count - 1;
 486
 487         _debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
 488
 489         ret = afs_store_data(mapping, first, last, offset, to);
 490         switch (ret) {
 491         case 0:
 492                 ret = count;
 493                 break;
 494
 495         default:
 496                 pr_notice("kAFS: Unexpected error from FS.StoreData %d\n", ret);
 497                 /* Fall through */
 498         case -EACCES:
 499         case -EPERM:
 500         case -ENOKEY:
 501         case -EKEYEXPIRED:
 502         case -EKEYREJECTED:
 503         case -EKEYREVOKED:
 504                 afs_redirty_pages(wbc, mapping, first, last);
 505                 mapping_set_error(mapping, ret);
 506                 break;
 507
 508         case -EDQUOT:
 509         case -ENOSPC:
 510                 afs_redirty_pages(wbc, mapping, first, last);
 511                 mapping_set_error(mapping, -ENOSPC);
 512                 break;
 513
 514         case -EROFS:
 515         case -EIO:
 516         case -EREMOTEIO:
 517         case -EFBIG:
 518         case -ENOENT:
 519         case -ENOMEDIUM:
 520         case -ENXIO:
 521                 afs_kill_pages(mapping, first, last);
 522                 mapping_set_error(mapping, ret);
 523                 break;
 524         }
 525
 526         _leave(" = %d", ret);
 527         return ret;
 528 }
 529
 530 /*
 531  * write a page back to the server
 532  * - the caller locked the page for us
 533  */
 534 int afs_writepage(struct page *page, struct writeback_control *wbc)
 535 {
 536         int ret;
 537
 538         _enter("{%lx},", page->index);
 539
 540         ret = afs_write_back_from_locked_page(page->mapping, wbc, page,
 541                                               wbc->range_end >> PAGE_SHIFT);
 542         if (ret < 0) {
 543                 _leave(" = %d", ret);
 544                 return 0;
 545         }
 546
 547         wbc->nr_to_write -= ret;
 548
 549         _leave(" = 0");
 550         return 0;
 551 }
 552
 553 /*
 554  * write a region of pages back to the server
 555  */
 556 static int afs_writepages_region(struct address_space *mapping,
 557                                  struct writeback_control *wbc,
 558                                  pgoff_t index, pgoff_t end, pgoff_t *_next)
 559 {
 560         struct page *page;
 561         int ret, n;
 562
 563         _enter(",,%lx,%lx,", index, end);
 564
 565         do {
 566                 n = find_get_pages_range_tag(mapping, &index, end,
 567                                         PAGECACHE_TAG_DIRTY, 1, &page);
 568                 if (!n)
 569                         break;
 570
 571                 _debug("wback %lx", page->index);
 572
 573                 /* at this point we hold neither mapping->tree_lock nor lock on
 574                  * the page itself: the page may be truncated or invalidated
 575                  * (changing page->mapping to NULL), or even swizzled back from
 576                  * swapper_space to tmpfs file mapping
 577                  */
 578                 ret = lock_page_killable(page);
 579                 if (ret < 0) {
 580                         put_page(page);
 581                         _leave(" = %d", ret);
 582                         return ret;
 583                 }
 584
 585                 if (page->mapping != mapping || !PageDirty(page)) {
 586                         unlock_page(page);
 587                         put_page(page);
 588                         continue;
 589                 }
 590
 591                 if (PageWriteback(page)) {
 592                         unlock_page(page);
 593                         if (wbc->sync_mode != WB_SYNC_NONE)
 594                                 wait_on_page_writeback(page);
 595                         put_page(page);
 596                         continue;
 597                 }
 598
 599                 if (!clear_page_dirty_for_io(page))
 600                         BUG();
 601                 ret = afs_write_back_from_locked_page(mapping, wbc, page, end);
 602                 put_page(page);
 603                 if (ret < 0) {
 604                         _leave(" = %d", ret);
 605                         return ret;
 606                 }
 607
 608                 wbc->nr_to_write -= ret;
 609
 610                 cond_resched();
 611         } while (index < end && wbc->nr_to_write > 0);
 612
 613         *_next = index;
 614         _leave(" = 0 [%lx]", *_next);
 615         return 0;
 616 }
 617
 618 /*
 619  * write some of the pending data back to the server
 620  */
 621 int afs_writepages(struct address_space *mapping,
 622                    struct writeback_control *wbc)
 623 {
 624         pgoff_t start, end, next;
 625         int ret;
 626
 627         _enter("");
 628
 629         if (wbc->range_cyclic) {
 630                 start = mapping->writeback_index;
 631                 end = -1;
 632                 ret = afs_writepages_region(mapping, wbc, start, end, &next);
 633                 if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
 634                         ret = afs_writepages_region(mapping, wbc, 0, start,
 635                                                     &next);
 636                 mapping->writeback_index = next;
 637         } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
 638                 end = (pgoff_t)(LLONG_MAX >> PAGE_SHIFT);
 639                 ret = afs_writepages_region(mapping, wbc, 0, end, &next);
 640                 if (wbc->nr_to_write > 0)
 641                         mapping->writeback_index = next;
 642         } else {
 643                 start = wbc->range_start >> PAGE_SHIFT;
 644                 end = wbc->range_end >> PAGE_SHIFT;
 645                 ret = afs_writepages_region(mapping, wbc, start, end, &next);
 646         }
 647
 648         _leave(" = %d", ret);
 649         return ret;
 650 }
 651
 652 /*
 653  * completion of write to server
 654  */
 655 void afs_pages_written_back(struct afs_vnode *vnode, struct afs_call *call)
 656 {
 657         struct pagevec pv;
 658         unsigned long priv;
 659         unsigned count, loop;
 660         pgoff_t first = call->first, last = call->last;
 661
 662         _enter("{%x:%u},{%lx-%lx}",
 663                vnode->fid.vid, vnode->fid.vnode, first, last);
 664
 665         pagevec_init(&pv);
 666
 667         do {
 668                 _debug("done %lx-%lx", first, last);
 669
 670                 count = last - first + 1;
 671                 if (count > PAGEVEC_SIZE)
 672                         count = PAGEVEC_SIZE;
 673                 pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
 674                                               first, count, pv.pages);
 675                 ASSERTCMP(pv.nr, ==, count);
 676
 677                 for (loop = 0; loop < count; loop++) {
 678                         priv = page_private(pv.pages[loop]);
 679                         trace_afs_page_dirty(vnode, tracepoint_string("clear"),
 680                                              pv.pages[loop]->index, priv);
 681                         set_page_private(pv.pages[loop], 0);
 682                         end_page_writeback(pv.pages[loop]);
 683                 }
 684                 first += count;
 685                 __pagevec_release(&pv);
 686         } while (first <= last);
 687
 688         afs_prune_wb_keys(vnode);
 689         _leave("");
 690 }
 691
 692 /*
 693  * write to an AFS file
 694  */
 695 ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
 696 {
 697         struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
 698         ssize_t result;
 699         size_t count = iov_iter_count(from);
 700
 701         _enter("{%x.%u},{%zu},",
 702                vnode->fid.vid, vnode->fid.vnode, count);
 703
 704         if (IS_SWAPFILE(&vnode->vfs_inode)) {
 705                 printk(KERN_INFO
 706                        "AFS: Attempt to write to active swap file!\n");
 707                 return -EBUSY;
 708         }
 709
 710         if (!count)
 711                 return 0;
 712
 713         result = generic_file_write_iter(iocb, from);
 714
 715         _leave(" = %zd", result);
 716         return result;
 717 }
 718
 719 /*
 720  * flush any dirty pages for this process, and check for write errors.
 721  * - the return status from this call provides a reliable indication of
 722  *   whether any write errors occurred for this process.
 723  */
 724 int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 725 {
 726         struct inode *inode = file_inode(file);
 727         struct afs_vnode *vnode = AFS_FS_I(inode);
 728
 729         _enter("{%x:%u},{n=%pD},%d",
 730                vnode->fid.vid, vnode->fid.vnode, file,
 731                datasync);
 732
 733         return file_write_and_wait_range(file, start, end);
 734 }
 735
 736 /*
 737  * Flush out all outstanding writes on a file opened for writing when it is
 738  * closed.
 739  */
 740 int afs_flush(struct file *file, fl_owner_t id)
 741 {
 742         _enter("");
 743
 744         if ((file->f_mode & FMODE_WRITE) == 0)
 745                 return 0;
 746
 747         return vfs_fsync(file, 0);
 748 }
 749
 750 /*
 751  * notification that a previously read-only page is about to become writable
 752  * - if it returns an error, the caller will deliver a bus error signal
 753  */
 754 int afs_page_mkwrite(struct vm_fault *vmf)
 755 {
 756         struct file *file = vmf->vma->vm_file;
 757         struct inode *inode = file_inode(file);
 758         struct afs_vnode *vnode = AFS_FS_I(inode);
 759         unsigned long priv;
 760
 761         _enter("{{%x:%u}},{%lx}",
 762                vnode->fid.vid, vnode->fid.vnode, vmf->page->index);
 763
 764         sb_start_pagefault(inode->i_sb);
 765
 766         /* Wait for the page to be written to the cache before we allow it to
 767          * be modified.  We then assume the entire page will need writing back.
 768          */
 769 #ifdef CONFIG_AFS_FSCACHE
 770         fscache_wait_on_page_write(vnode->cache, vmf->page);
 771 #endif
 772
 773         if (PageWriteback(vmf->page) &&
 774             wait_on_page_bit_killable(vmf->page, PG_writeback) < 0)
 775                 return VM_FAULT_RETRY;
 776
 777         if (lock_page_killable(vmf->page) < 0)
 778                 return VM_FAULT_RETRY;
 779
 780         /* We mustn't change page->private until writeback is complete as that
 781          * details the portion of the page we need to write back and we might
 782          * need to redirty the page if there's a problem.
 783          */
 784         wait_on_page_writeback(vmf->page);
 785
 786         priv = (unsigned long)PAGE_SIZE << AFS_PRIV_SHIFT; /* To */
 787         priv |= 0; /* From */
 788         trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"),
 789                              vmf->page->index, priv);
 790         SetPagePrivate(vmf->page);
 791         set_page_private(vmf->page, priv);
 792
 793         sb_end_pagefault(inode->i_sb);
 794         return VM_FAULT_LOCKED;
 795 }
 796
 797 /*
 798  * Prune the keys cached for writeback.  The caller must hold vnode->wb_lock.
 799  */
 800 void afs_prune_wb_keys(struct afs_vnode *vnode)
 801 {
 802         LIST_HEAD(graveyard);
 803         struct afs_wb_key *wbk, *tmp;
 804
 805         /* Discard unused keys */
 806         spin_lock(&vnode->wb_lock);
 807
 808         if (!mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
 809             !mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_DIRTY)) {
 810                 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
 811                         if (refcount_read(&wbk->usage) == 1)
 812                                 list_move(&wbk->vnode_link, &graveyard);
 813                 }
 814         }
 815
 816         spin_unlock(&vnode->wb_lock);
 817
 818         while (!list_empty(&graveyard)) {
 819                 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
 820                 list_del(&wbk->vnode_link);
 821                 afs_put_wb_key(wbk);
 822         }
 823 }
 824
 825 /*
 826  * Clean up a page during invalidation.
 827  */
 828 int afs_launder_page(struct page *page)
 829 {
 830         struct address_space *mapping = page->mapping;
 831         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 832         unsigned long priv;
 833         unsigned int f, t;
 834         int ret = 0;
 835
 836         _enter("{%lx}", page->index);
 837
 838         priv = page_private(page);
 839         if (clear_page_dirty_for_io(page)) {
 840                 f = 0;
 841                 t = PAGE_SIZE;
 842                 if (PagePrivate(page)) {
 843                         f = priv & AFS_PRIV_MAX;
 844                         t = priv >> AFS_PRIV_SHIFT;
 845                 }
 846
 847                 trace_afs_page_dirty(vnode, tracepoint_string("launder"),
 848                                      page->index, priv);
 849                 ret = afs_store_data(mapping, page->index, page->index, t, f);
 850         }
 851
 852         trace_afs_page_dirty(vnode, tracepoint_string("laundered"),
 853                              page->index, priv);
 854         set_page_private(page, 0);
 855         ClearPagePrivate(page);
 856
 857 #ifdef CONFIG_AFS_FSCACHE
 858         if (PageFsCache(page)) {
 859                 fscache_wait_on_page_write(vnode->cache, page);
 860                 fscache_uncache_page(vnode->cache, page);
 861         }
 862 #endif
 863         return ret;
 864 }