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 ([email protected])
   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         size_t p;
  37         void *data;
  38         int ret;
  39
  40         _enter(",,%llu", (unsigned long long)pos);
  41
  42         if (pos >= vnode->vfs_inode.i_size) {
  43                 p = pos & ~PAGE_MASK;
  44                 ASSERTCMP(p + len, <=, PAGE_SIZE);
  45                 data = kmap(page);
  46                 memset(data + p, 0, len);
  47                 kunmap(page);
  48                 return 0;
  49         }
  50
  51         req = kzalloc(sizeof(struct afs_read) + sizeof(struct page *),
  52                       GFP_KERNEL);
  53         if (!req)
  54                 return -ENOMEM;
  55
  56         refcount_set(&req->usage, 1);
  57         req->pos = pos;
  58         req->len = len;
  59         req->nr_pages = 1;
  60         req->pages = req->array;
  61         req->pages[0] = page;
  62         get_page(page);
  63
  64         ret = afs_fetch_data(vnode, key, req);
  65         afs_put_read(req);
  66         if (ret < 0) {
  67                 if (ret == -ENOENT) {
  68                         _debug("got NOENT from server"
  69                                " - marking file deleted and stale");
  70                         set_bit(AFS_VNODE_DELETED, &vnode->flags);
  71                         ret = -ESTALE;
  72                 }
  73         }
  74
  75         _leave(" = %d", ret);
  76         return ret;
  77 }
  78
  79 /*
  80  * prepare to perform part of a write to a page
  81  */
  82 int afs_write_begin(struct file *file, struct address_space *mapping,
  83                     loff_t pos, unsigned len, unsigned flags,
  84                     struct page **pagep, void **fsdata)
  85 {
  86         struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
  87         struct page *page;
  88         struct key *key = afs_file_key(file);
  89         unsigned long priv;
  90         unsigned f, from = pos & (PAGE_SIZE - 1);
  91         unsigned t, to = from + len;
  92         pgoff_t index = pos >> PAGE_SHIFT;
  93         int ret;
  94
  95         _enter("{%llx:%llu},{%lx},%u,%u",
  96                vnode->fid.vid, vnode->fid.vnode, index, from, to);
  97
  98         /* We want to store information about how much of a page is altered in
  99          * page->private.
 100          */
 101         BUILD_BUG_ON(PAGE_SIZE > 32768 && sizeof(page->private) < 8);
 102
 103         page = grab_cache_page_write_begin(mapping, index, flags);
 104         if (!page)
 105                 return -ENOMEM;
 106
 107         if (!PageUptodate(page) && len != PAGE_SIZE) {
 108                 ret = afs_fill_page(vnode, key, pos & PAGE_MASK, PAGE_SIZE, page);
 109                 if (ret < 0) {
 110                         unlock_page(page);
 111                         put_page(page);
 112                         _leave(" = %d [prep]", ret);
 113                         return ret;
 114                 }
 115                 SetPageUptodate(page);
 116         }
 117
 118         /* page won't leak in error case: it eventually gets cleaned off LRU */
 119         *pagep = page;
 120
 121 try_again:
 122         /* See if this page is already partially written in a way that we can
 123          * merge the new write with.
 124          */
 125         t = f = 0;
 126         if (PagePrivate(page)) {
 127                 priv = page_private(page);
 128                 f = priv & AFS_PRIV_MAX;
 129                 t = priv >> AFS_PRIV_SHIFT;
 130                 ASSERTCMP(f, <=, t);
 131         }
 132
 133         if (f != t) {
 134                 if (PageWriteback(page)) {
 135                         trace_afs_page_dirty(vnode, tracepoint_string("alrdy"),
 136                                              page->index, priv);
 137                         goto flush_conflicting_write;
 138                 }
 139                 /* If the file is being filled locally, allow inter-write
 140                  * spaces to be merged into writes.  If it's not, only write
 141                  * back what the user gives us.
 142                  */
 143                 if (!test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags) &&
 144                     (to < f || from > t))
 145                         goto flush_conflicting_write;
 146                 if (from < f)
 147                         f = from;
 148                 if (to > t)
 149                         t = to;
 150         } else {
 151                 f = from;
 152                 t = to;
 153         }
 154
 155         priv = (unsigned long)t << AFS_PRIV_SHIFT;
 156         priv |= f;
 157         trace_afs_page_dirty(vnode, tracepoint_string("begin"),
 158                              page->index, priv);
 159         SetPagePrivate(page);
 160         set_page_private(page, priv);
 161         _leave(" = 0");
 162         return 0;
 163
 164         /* The previous write and this write aren't adjacent or overlapping, so
 165          * flush the page out.
 166          */
 167 flush_conflicting_write:
 168         _debug("flush conflict");
 169         ret = write_one_page(page);
 170         if (ret < 0) {
 171                 _leave(" = %d", ret);
 172                 return ret;
 173         }
 174
 175         ret = lock_page_killable(page);
 176         if (ret < 0) {
 177                 _leave(" = %d", ret);
 178                 return ret;
 179         }
 180         goto try_again;
 181 }
 182
 183 /*
 184  * finalise part of a write to a page
 185  */
 186 int afs_write_end(struct file *file, struct address_space *mapping,
 187                   loff_t pos, unsigned len, unsigned copied,
 188                   struct page *page, void *fsdata)
 189 {
 190         struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
 191         struct key *key = afs_file_key(file);
 192         loff_t i_size, maybe_i_size;
 193         int ret;
 194
 195         _enter("{%llx:%llu},{%lx}",
 196                vnode->fid.vid, vnode->fid.vnode, page->index);
 197
 198         maybe_i_size = pos + copied;
 199
 200         i_size = i_size_read(&vnode->vfs_inode);
 201         if (maybe_i_size > i_size) {
 202                 spin_lock(&vnode->wb_lock);
 203                 i_size = i_size_read(&vnode->vfs_inode);
 204                 if (maybe_i_size > i_size)
 205                         i_size_write(&vnode->vfs_inode, maybe_i_size);
 206                 spin_unlock(&vnode->wb_lock);
 207         }
 208
 209         if (!PageUptodate(page)) {
 210                 if (copied < len) {
 211                         /* Try and load any missing data from the server.  The
 212                          * unmarshalling routine will take care of clearing any
 213                          * bits that are beyond the EOF.
 214                          */
 215                         ret = afs_fill_page(vnode, key, pos + copied,
 216                                             len - copied, page);
 217                         if (ret < 0)
 218                                 goto out;
 219                 }
 220                 SetPageUptodate(page);
 221         }
 222
 223         set_page_dirty(page);
 224         if (PageDirty(page))
 225                 _debug("dirtied");
 226         ret = copied;
 227
 228 out:
 229         unlock_page(page);
 230         put_page(page);
 231         return ret;
 232 }
 233
 234 /*
 235  * kill all the pages in the given range
 236  */
 237 static void afs_kill_pages(struct address_space *mapping,
 238                            pgoff_t first, pgoff_t last)
 239 {
 240         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 241         struct pagevec pv;
 242         unsigned count, loop;
 243
 244         _enter("{%llx:%llu},%lx-%lx",
 245                vnode->fid.vid, vnode->fid.vnode, first, last);
 246
 247         pagevec_init(&pv);
 248
 249         do {
 250                 _debug("kill %lx-%lx", first, last);
 251
 252                 count = last - first + 1;
 253                 if (count > PAGEVEC_SIZE)
 254                         count = PAGEVEC_SIZE;
 255                 pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
 256                 ASSERTCMP(pv.nr, ==, count);
 257
 258                 for (loop = 0; loop < count; loop++) {
 259                         struct page *page = pv.pages[loop];
 260                         ClearPageUptodate(page);
 261                         SetPageError(page);
 262                         end_page_writeback(page);
 263                         if (page->index >= first)
 264                                 first = page->index + 1;
 265                         lock_page(page);
 266                         generic_error_remove_page(mapping, page);
 267                         unlock_page(page);
 268                 }
 269
 270                 __pagevec_release(&pv);
 271         } while (first <= last);
 272
 273         _leave("");
 274 }
 275
 276 /*
 277  * Redirty all the pages in a given range.
 278  */
 279 static void afs_redirty_pages(struct writeback_control *wbc,
 280                               struct address_space *mapping,
 281                               pgoff_t first, pgoff_t last)
 282 {
 283         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 284         struct pagevec pv;
 285         unsigned count, loop;
 286
 287         _enter("{%llx:%llu},%lx-%lx",
 288                vnode->fid.vid, vnode->fid.vnode, first, last);
 289
 290         pagevec_init(&pv);
 291
 292         do {
 293                 _debug("redirty %lx-%lx", first, last);
 294
 295                 count = last - first + 1;
 296                 if (count > PAGEVEC_SIZE)
 297                         count = PAGEVEC_SIZE;
 298                 pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
 299                 ASSERTCMP(pv.nr, ==, count);
 300
 301                 for (loop = 0; loop < count; loop++) {
 302                         struct page *page = pv.pages[loop];
 303
 304                         redirty_page_for_writepage(wbc, page);
 305                         end_page_writeback(page);
 306                         if (page->index >= first)
 307                                 first = page->index + 1;
 308                 }
 309
 310                 __pagevec_release(&pv);
 311         } while (first <= last);
 312
 313         _leave("");
 314 }
 315
 316 /*
 317  * completion of write to server
 318  */
 319 static void afs_pages_written_back(struct afs_vnode *vnode,
 320                                    pgoff_t first, pgoff_t last)
 321 {
 322         struct pagevec pv;
 323         unsigned long priv;
 324         unsigned count, loop;
 325
 326         _enter("{%llx:%llu},{%lx-%lx}",
 327                vnode->fid.vid, vnode->fid.vnode, first, last);
 328
 329         pagevec_init(&pv);
 330
 331         do {
 332                 _debug("done %lx-%lx", first, last);
 333
 334                 count = last - first + 1;
 335                 if (count > PAGEVEC_SIZE)
 336                         count = PAGEVEC_SIZE;
 337                 pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
 338                                               first, count, pv.pages);
 339                 ASSERTCMP(pv.nr, ==, count);
 340
 341                 for (loop = 0; loop < count; loop++) {
 342                         priv = page_private(pv.pages[loop]);
 343                         trace_afs_page_dirty(vnode, tracepoint_string("clear"),
 344                                              pv.pages[loop]->index, priv);
 345                         set_page_private(pv.pages[loop], 0);
 346                         end_page_writeback(pv.pages[loop]);
 347                 }
 348                 first += count;
 349                 __pagevec_release(&pv);
 350         } while (first <= last);
 351
 352         afs_prune_wb_keys(vnode);
 353         _leave("");
 354 }
 355
 356 /*
 357  * write to a file
 358  */
 359 static int afs_store_data(struct address_space *mapping,
 360                           pgoff_t first, pgoff_t last,
 361                           unsigned offset, unsigned to)
 362 {
 363         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 364         struct afs_fs_cursor fc;
 365         struct afs_status_cb *scb;
 366         struct afs_wb_key *wbk = NULL;
 367         struct list_head *p;
 368         int ret = -ENOKEY, ret2;
 369
 370         _enter("%s{%llx:%llu.%u},%lx,%lx,%x,%x",
 371                vnode->volume->name,
 372                vnode->fid.vid,
 373                vnode->fid.vnode,
 374                vnode->fid.unique,
 375                first, last, offset, to);
 376
 377         scb = kzalloc(sizeof(struct afs_status_cb), GFP_NOFS);
 378         if (!scb)
 379                 return -ENOMEM;
 380
 381         spin_lock(&vnode->wb_lock);
 382         p = vnode->wb_keys.next;
 383
 384         /* Iterate through the list looking for a valid key to use. */
 385 try_next_key:
 386         while (p != &vnode->wb_keys) {
 387                 wbk = list_entry(p, struct afs_wb_key, vnode_link);
 388                 _debug("wbk %u", key_serial(wbk->key));
 389                 ret2 = key_validate(wbk->key);
 390                 if (ret2 == 0)
 391                         goto found_key;
 392                 if (ret == -ENOKEY)
 393                         ret = ret2;
 394                 p = p->next;
 395         }
 396
 397         spin_unlock(&vnode->wb_lock);
 398         afs_put_wb_key(wbk);
 399         kfree(scb);
 400         _leave(" = %d [no keys]", ret);
 401         return ret;
 402
 403 found_key:
 404         refcount_inc(&wbk->usage);
 405         spin_unlock(&vnode->wb_lock);
 406
 407         _debug("USE WB KEY %u", key_serial(wbk->key));
 408
 409         ret = -ERESTARTSYS;
 410         if (afs_begin_vnode_operation(&fc, vnode, wbk->key, false)) {
 411                 afs_dataversion_t data_version = vnode->status.data_version + 1;
 412
 413                 while (afs_select_fileserver(&fc)) {
 414                         fc.cb_break = afs_calc_vnode_cb_break(vnode);
 415                         afs_fs_store_data(&fc, mapping, first, last, offset, to, scb);
 416                 }
 417
 418                 afs_check_for_remote_deletion(&fc, vnode);
 419                 afs_vnode_commit_status(&fc, vnode, fc.cb_break,
 420                                         &data_version, scb);
 421                 if (fc.ac.error == 0)
 422                         afs_pages_written_back(vnode, first, last);
 423                 ret = afs_end_vnode_operation(&fc);
 424         }
 425
 426         switch (ret) {
 427         case 0:
 428                 afs_stat_v(vnode, n_stores);
 429                 atomic_long_add((last * PAGE_SIZE + to) -
 430                                 (first * PAGE_SIZE + offset),
 431                                 &afs_v2net(vnode)->n_store_bytes);
 432                 break;
 433         case -EACCES:
 434         case -EPERM:
 435         case -ENOKEY:
 436         case -EKEYEXPIRED:
 437         case -EKEYREJECTED:
 438         case -EKEYREVOKED:
 439                 _debug("next");
 440                 spin_lock(&vnode->wb_lock);
 441                 p = wbk->vnode_link.next;
 442                 afs_put_wb_key(wbk);
 443                 goto try_next_key;
 444         }
 445
 446         afs_put_wb_key(wbk);
 447         kfree(scb);
 448         _leave(" = %d", ret);
 449         return ret;
 450 }
 451
 452 /*
 453  * Synchronously write back the locked page and any subsequent non-locked dirty
 454  * pages.
 455  */
 456 static int afs_write_back_from_locked_page(struct address_space *mapping,
 457                                            struct writeback_control *wbc,
 458                                            struct page *primary_page,
 459                                            pgoff_t final_page)
 460 {
 461         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 462         struct page *pages[8], *page;
 463         unsigned long count, priv;
 464         unsigned n, offset, to, f, t;
 465         pgoff_t start, first, last;
 466         int loop, ret;
 467
 468         _enter(",%lx", primary_page->index);
 469
 470         count = 1;
 471         if (test_set_page_writeback(primary_page))
 472                 BUG();
 473
 474         /* Find all consecutive lockable dirty pages that have contiguous
 475          * written regions, stopping when we find a page that is not
 476          * immediately lockable, is not dirty or is missing, or we reach the
 477          * end of the range.
 478          */
 479         start = primary_page->index;
 480         priv = page_private(primary_page);
 481         offset = priv & AFS_PRIV_MAX;
 482         to = priv >> AFS_PRIV_SHIFT;
 483         trace_afs_page_dirty(vnode, tracepoint_string("store"),
 484                              primary_page->index, priv);
 485
 486         WARN_ON(offset == to);
 487         if (offset == to)
 488                 trace_afs_page_dirty(vnode, tracepoint_string("WARN"),
 489                                      primary_page->index, priv);
 490
 491         if (start >= final_page ||
 492             (to < PAGE_SIZE && !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)))
 493                 goto no_more;
 494
 495         start++;
 496         do {
 497                 _debug("more %lx [%lx]", start, count);
 498                 n = final_page - start + 1;
 499                 if (n > ARRAY_SIZE(pages))
 500                         n = ARRAY_SIZE(pages);
 501                 n = find_get_pages_contig(mapping, start, ARRAY_SIZE(pages), pages);
 502                 _debug("fgpc %u", n);
 503                 if (n == 0)
 504                         goto no_more;
 505                 if (pages[0]->index != start) {
 506                         do {
 507                                 put_page(pages[--n]);
 508                         } while (n > 0);
 509                         goto no_more;
 510                 }
 511
 512                 for (loop = 0; loop < n; loop++) {
 513                         page = pages[loop];
 514                         if (to != PAGE_SIZE &&
 515                             !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags))
 516                                 break;
 517                         if (page->index > final_page)
 518                                 break;
 519                         if (!trylock_page(page))
 520                                 break;
 521                         if (!PageDirty(page) || PageWriteback(page)) {
 522                                 unlock_page(page);
 523                                 break;
 524                         }
 525
 526                         priv = page_private(page);
 527                         f = priv & AFS_PRIV_MAX;
 528                         t = priv >> AFS_PRIV_SHIFT;
 529                         if (f != 0 &&
 530                             !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)) {
 531                                 unlock_page(page);
 532                                 break;
 533                         }
 534                         to = t;
 535
 536                         trace_afs_page_dirty(vnode, tracepoint_string("store+"),
 537                                              page->index, priv);
 538
 539                         if (!clear_page_dirty_for_io(page))
 540                                 BUG();
 541                         if (test_set_page_writeback(page))
 542                                 BUG();
 543                         unlock_page(page);
 544                         put_page(page);
 545                 }
 546                 count += loop;
 547                 if (loop < n) {
 548                         for (; loop < n; loop++)
 549                                 put_page(pages[loop]);
 550                         goto no_more;
 551                 }
 552
 553                 start += loop;
 554         } while (start <= final_page && count < 65536);
 555
 556 no_more:
 557         /* We now have a contiguous set of dirty pages, each with writeback
 558          * set; the first page is still locked at this point, but all the rest
 559          * have been unlocked.
 560          */
 561         unlock_page(primary_page);
 562
 563         first = primary_page->index;
 564         last = first + count - 1;
 565
 566         _debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
 567
 568         ret = afs_store_data(mapping, first, last, offset, to);
 569         switch (ret) {
 570         case 0:
 571                 ret = count;
 572                 break;
 573
 574         default:
 575                 pr_notice("kAFS: Unexpected error from FS.StoreData %d\n", ret);
 576                 /* Fall through */
 577         case -EACCES:
 578         case -EPERM:
 579         case -ENOKEY:
 580         case -EKEYEXPIRED:
 581         case -EKEYREJECTED:
 582         case -EKEYREVOKED:
 583                 afs_redirty_pages(wbc, mapping, first, last);
 584                 mapping_set_error(mapping, ret);
 585                 break;
 586
 587         case -EDQUOT:
 588         case -ENOSPC:
 589                 afs_redirty_pages(wbc, mapping, first, last);
 590                 mapping_set_error(mapping, -ENOSPC);
 591                 break;
 592
 593         case -EROFS:
 594         case -EIO:
 595         case -EREMOTEIO:
 596         case -EFBIG:
 597         case -ENOENT:
 598         case -ENOMEDIUM:
 599         case -ENXIO:
 600                 trace_afs_file_error(vnode, ret, afs_file_error_writeback_fail);
 601                 afs_kill_pages(mapping, first, last);
 602                 mapping_set_error(mapping, ret);
 603                 break;
 604         }
 605
 606         _leave(" = %d", ret);
 607         return ret;
 608 }
 609
 610 /*
 611  * write a page back to the server
 612  * - the caller locked the page for us
 613  */
 614 int afs_writepage(struct page *page, struct writeback_control *wbc)
 615 {
 616         int ret;
 617
 618         _enter("{%lx},", page->index);
 619
 620         ret = afs_write_back_from_locked_page(page->mapping, wbc, page,
 621                                               wbc->range_end >> PAGE_SHIFT);
 622         if (ret < 0) {
 623                 _leave(" = %d", ret);
 624                 return 0;
 625         }
 626
 627         wbc->nr_to_write -= ret;
 628
 629         _leave(" = 0");
 630         return 0;
 631 }
 632
 633 /*
 634  * write a region of pages back to the server
 635  */
 636 static int afs_writepages_region(struct address_space *mapping,
 637                                  struct writeback_control *wbc,
 638                                  pgoff_t index, pgoff_t end, pgoff_t *_next)
 639 {
 640         struct page *page;
 641         int ret, n;
 642
 643         _enter(",,%lx,%lx,", index, end);
 644
 645         do {
 646                 n = find_get_pages_range_tag(mapping, &index, end,
 647                                         PAGECACHE_TAG_DIRTY, 1, &page);
 648                 if (!n)
 649                         break;
 650
 651                 _debug("wback %lx", page->index);
 652
 653                 /*
 654                  * at this point we hold neither the i_pages lock nor the
 655                  * page lock: the page may be truncated or invalidated
 656                  * (changing page->mapping to NULL), or even swizzled
 657                  * back from swapper_space to tmpfs file mapping
 658                  */
 659                 ret = lock_page_killable(page);
 660                 if (ret < 0) {
 661                         put_page(page);
 662                         _leave(" = %d", ret);
 663                         return ret;
 664                 }
 665
 666                 if (page->mapping != mapping || !PageDirty(page)) {
 667                         unlock_page(page);
 668                         put_page(page);
 669                         continue;
 670                 }
 671
 672                 if (PageWriteback(page)) {
 673                         unlock_page(page);
 674                         if (wbc->sync_mode != WB_SYNC_NONE)
 675                                 wait_on_page_writeback(page);
 676                         put_page(page);
 677                         continue;
 678                 }
 679
 680                 if (!clear_page_dirty_for_io(page))
 681                         BUG();
 682                 ret = afs_write_back_from_locked_page(mapping, wbc, page, end);
 683                 put_page(page);
 684                 if (ret < 0) {
 685                         _leave(" = %d", ret);
 686                         return ret;
 687                 }
 688
 689                 wbc->nr_to_write -= ret;
 690
 691                 cond_resched();
 692         } while (index < end && wbc->nr_to_write > 0);
 693
 694         *_next = index;
 695         _leave(" = 0 [%lx]", *_next);
 696         return 0;
 697 }
 698
 699 /*
 700  * write some of the pending data back to the server
 701  */
 702 int afs_writepages(struct address_space *mapping,
 703                    struct writeback_control *wbc)
 704 {
 705         pgoff_t start, end, next;
 706         int ret;
 707
 708         _enter("");
 709
 710         if (wbc->range_cyclic) {
 711                 start = mapping->writeback_index;
 712                 end = -1;
 713                 ret = afs_writepages_region(mapping, wbc, start, end, &next);
 714                 if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
 715                         ret = afs_writepages_region(mapping, wbc, 0, start,
 716                                                     &next);
 717                 mapping->writeback_index = next;
 718         } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
 719                 end = (pgoff_t)(LLONG_MAX >> PAGE_SHIFT);
 720                 ret = afs_writepages_region(mapping, wbc, 0, end, &next);
 721                 if (wbc->nr_to_write > 0)
 722                         mapping->writeback_index = next;
 723         } else {
 724                 start = wbc->range_start >> PAGE_SHIFT;
 725                 end = wbc->range_end >> PAGE_SHIFT;
 726                 ret = afs_writepages_region(mapping, wbc, start, end, &next);
 727         }
 728
 729         _leave(" = %d", ret);
 730         return ret;
 731 }
 732
 733 /*
 734  * write to an AFS file
 735  */
 736 ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
 737 {
 738         struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
 739         ssize_t result;
 740         size_t count = iov_iter_count(from);
 741
 742         _enter("{%llx:%llu},{%zu},",
 743                vnode->fid.vid, vnode->fid.vnode, count);
 744
 745         if (IS_SWAPFILE(&vnode->vfs_inode)) {
 746                 printk(KERN_INFO
 747                        "AFS: Attempt to write to active swap file!\n");
 748                 return -EBUSY;
 749         }
 750
 751         if (!count)
 752                 return 0;
 753
 754         result = generic_file_write_iter(iocb, from);
 755
 756         _leave(" = %zd", result);
 757         return result;
 758 }
 759
 760 /*
 761  * flush any dirty pages for this process, and check for write errors.
 762  * - the return status from this call provides a reliable indication of
 763  *   whether any write errors occurred for this process.
 764  */
 765 int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 766 {
 767         struct inode *inode = file_inode(file);
 768         struct afs_vnode *vnode = AFS_FS_I(inode);
 769
 770         _enter("{%llx:%llu},{n=%pD},%d",
 771                vnode->fid.vid, vnode->fid.vnode, file,
 772                datasync);
 773
 774         return file_write_and_wait_range(file, start, end);
 775 }
 776
 777 /*
 778  * notification that a previously read-only page is about to become writable
 779  * - if it returns an error, the caller will deliver a bus error signal
 780  */
 781 vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
 782 {
 783         struct file *file = vmf->vma->vm_file;
 784         struct inode *inode = file_inode(file);
 785         struct afs_vnode *vnode = AFS_FS_I(inode);
 786         unsigned long priv;
 787
 788         _enter("{{%llx:%llu}},{%lx}",
 789                vnode->fid.vid, vnode->fid.vnode, vmf->page->index);
 790
 791         sb_start_pagefault(inode->i_sb);
 792
 793         /* Wait for the page to be written to the cache before we allow it to
 794          * be modified.  We then assume the entire page will need writing back.
 795          */
 796 #ifdef CONFIG_AFS_FSCACHE
 797         fscache_wait_on_page_write(vnode->cache, vmf->page);
 798 #endif
 799
 800         if (PageWriteback(vmf->page) &&
 801             wait_on_page_bit_killable(vmf->page, PG_writeback) < 0)
 802                 return VM_FAULT_RETRY;
 803
 804         if (lock_page_killable(vmf->page) < 0)
 805                 return VM_FAULT_RETRY;
 806
 807         /* We mustn't change page->private until writeback is complete as that
 808          * details the portion of the page we need to write back and we might
 809          * need to redirty the page if there's a problem.
 810          */
 811         wait_on_page_writeback(vmf->page);
 812
 813         priv = (unsigned long)PAGE_SIZE << AFS_PRIV_SHIFT; /* To */
 814         priv |= 0; /* From */
 815         trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"),
 816                              vmf->page->index, priv);
 817         SetPagePrivate(vmf->page);
 818         set_page_private(vmf->page, priv);
 819
 820         sb_end_pagefault(inode->i_sb);
 821         return VM_FAULT_LOCKED;
 822 }
 823
 824 /*
 825  * Prune the keys cached for writeback.  The caller must hold vnode->wb_lock.
 826  */
 827 void afs_prune_wb_keys(struct afs_vnode *vnode)
 828 {
 829         LIST_HEAD(graveyard);
 830         struct afs_wb_key *wbk, *tmp;
 831
 832         /* Discard unused keys */
 833         spin_lock(&vnode->wb_lock);
 834
 835         if (!mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
 836             !mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_DIRTY)) {
 837                 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
 838                         if (refcount_read(&wbk->usage) == 1)
 839                                 list_move(&wbk->vnode_link, &graveyard);
 840                 }
 841         }
 842
 843         spin_unlock(&vnode->wb_lock);
 844
 845         while (!list_empty(&graveyard)) {
 846                 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
 847                 list_del(&wbk->vnode_link);
 848                 afs_put_wb_key(wbk);
 849         }
 850 }
 851
 852 /*
 853  * Clean up a page during invalidation.
 854  */
 855 int afs_launder_page(struct page *page)
 856 {
 857         struct address_space *mapping = page->mapping;
 858         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 859         unsigned long priv;
 860         unsigned int f, t;
 861         int ret = 0;
 862
 863         _enter("{%lx}", page->index);
 864
 865         priv = page_private(page);
 866         if (clear_page_dirty_for_io(page)) {
 867                 f = 0;
 868                 t = PAGE_SIZE;
 869                 if (PagePrivate(page)) {
 870                         f = priv & AFS_PRIV_MAX;
 871                         t = priv >> AFS_PRIV_SHIFT;
 872                 }
 873
 874                 trace_afs_page_dirty(vnode, tracepoint_string("launder"),
 875                                      page->index, priv);
 876                 ret = afs_store_data(mapping, page->index, page->index, t, f);
 877         }
 878
 879         trace_afs_page_dirty(vnode, tracepoint_string("laundered"),
 880                              page->index, priv);
 881         set_page_private(page, 0);
 882         ClearPagePrivate(page);
 883
 884 #ifdef CONFIG_AFS_FSCACHE
 885         if (PageFsCache(page)) {
 886                 fscache_wait_on_page_write(vnode->cache, page);
 887                 fscache_uncache_page(vnode->cache, page);
 888         }
 889 #endif
 890         return ret;
 891 }