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         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  * write to a file
 318  */
 319 static int afs_store_data(struct address_space *mapping,
 320                           pgoff_t first, pgoff_t last,
 321                           unsigned offset, unsigned to)
 322 {
 323         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 324         struct afs_fs_cursor fc;
 325         struct afs_wb_key *wbk = NULL;
 326         struct list_head *p;
 327         int ret = -ENOKEY, ret2;
 328
 329         _enter("%s{%llx:%llu.%u},%lx,%lx,%x,%x",
 330                vnode->volume->name,
 331                vnode->fid.vid,
 332                vnode->fid.vnode,
 333                vnode->fid.unique,
 334                first, last, offset, to);
 335
 336         spin_lock(&vnode->wb_lock);
 337         p = vnode->wb_keys.next;
 338
 339         /* Iterate through the list looking for a valid key to use. */
 340 try_next_key:
 341         while (p != &vnode->wb_keys) {
 342                 wbk = list_entry(p, struct afs_wb_key, vnode_link);
 343                 _debug("wbk %u", key_serial(wbk->key));
 344                 ret2 = key_validate(wbk->key);
 345                 if (ret2 == 0)
 346                         goto found_key;
 347                 if (ret == -ENOKEY)
 348                         ret = ret2;
 349                 p = p->next;
 350         }
 351
 352         spin_unlock(&vnode->wb_lock);
 353         afs_put_wb_key(wbk);
 354         _leave(" = %d [no keys]", ret);
 355         return ret;
 356
 357 found_key:
 358         refcount_inc(&wbk->usage);
 359         spin_unlock(&vnode->wb_lock);
 360
 361         _debug("USE WB KEY %u", key_serial(wbk->key));
 362
 363         ret = -ERESTARTSYS;
 364         if (afs_begin_vnode_operation(&fc, vnode, wbk->key)) {
 365                 while (afs_select_fileserver(&fc)) {
 366                         fc.cb_break = afs_calc_vnode_cb_break(vnode);
 367                         afs_fs_store_data(&fc, mapping, first, last, offset, to);
 368                 }
 369
 370                 afs_check_for_remote_deletion(&fc, fc.vnode);
 371                 afs_vnode_commit_status(&fc, vnode, fc.cb_break);
 372                 ret = afs_end_vnode_operation(&fc);
 373         }
 374
 375         switch (ret) {
 376         case 0:
 377                 afs_stat_v(vnode, n_stores);
 378                 atomic_long_add((last * PAGE_SIZE + to) -
 379                                 (first * PAGE_SIZE + offset),
 380                                 &afs_v2net(vnode)->n_store_bytes);
 381                 break;
 382         case -EACCES:
 383         case -EPERM:
 384         case -ENOKEY:
 385         case -EKEYEXPIRED:
 386         case -EKEYREJECTED:
 387         case -EKEYREVOKED:
 388                 _debug("next");
 389                 spin_lock(&vnode->wb_lock);
 390                 p = wbk->vnode_link.next;
 391                 afs_put_wb_key(wbk);
 392                 goto try_next_key;
 393         }
 394
 395         afs_put_wb_key(wbk);
 396         _leave(" = %d", ret);
 397         return ret;
 398 }
 399
 400 /*
 401  * Synchronously write back the locked page and any subsequent non-locked dirty
 402  * pages.
 403  */
 404 static int afs_write_back_from_locked_page(struct address_space *mapping,
 405                                            struct writeback_control *wbc,
 406                                            struct page *primary_page,
 407                                            pgoff_t final_page)
 408 {
 409         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 410         struct page *pages[8], *page;
 411         unsigned long count, priv;
 412         unsigned n, offset, to, f, t;
 413         pgoff_t start, first, last;
 414         int loop, ret;
 415
 416         _enter(",%lx", primary_page->index);
 417
 418         count = 1;
 419         if (test_set_page_writeback(primary_page))
 420                 BUG();
 421
 422         /* Find all consecutive lockable dirty pages that have contiguous
 423          * written regions, stopping when we find a page that is not
 424          * immediately lockable, is not dirty or is missing, or we reach the
 425          * end of the range.
 426          */
 427         start = primary_page->index;
 428         priv = page_private(primary_page);
 429         offset = priv & AFS_PRIV_MAX;
 430         to = priv >> AFS_PRIV_SHIFT;
 431         trace_afs_page_dirty(vnode, tracepoint_string("store"),
 432                              primary_page->index, priv);
 433
 434         WARN_ON(offset == to);
 435         if (offset == to)
 436                 trace_afs_page_dirty(vnode, tracepoint_string("WARN"),
 437                                      primary_page->index, priv);
 438
 439         if (start >= final_page ||
 440             (to < PAGE_SIZE && !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)))
 441                 goto no_more;
 442
 443         start++;
 444         do {
 445                 _debug("more %lx [%lx]", start, count);
 446                 n = final_page - start + 1;
 447                 if (n > ARRAY_SIZE(pages))
 448                         n = ARRAY_SIZE(pages);
 449                 n = find_get_pages_contig(mapping, start, ARRAY_SIZE(pages), pages);
 450                 _debug("fgpc %u", n);
 451                 if (n == 0)
 452                         goto no_more;
 453                 if (pages[0]->index != start) {
 454                         do {
 455                                 put_page(pages[--n]);
 456                         } while (n > 0);
 457                         goto no_more;
 458                 }
 459
 460                 for (loop = 0; loop < n; loop++) {
 461                         page = pages[loop];
 462                         if (to != PAGE_SIZE &&
 463                             !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags))
 464                                 break;
 465                         if (page->index > final_page)
 466                                 break;
 467                         if (!trylock_page(page))
 468                                 break;
 469                         if (!PageDirty(page) || PageWriteback(page)) {
 470                                 unlock_page(page);
 471                                 break;
 472                         }
 473
 474                         priv = page_private(page);
 475                         f = priv & AFS_PRIV_MAX;
 476                         t = priv >> AFS_PRIV_SHIFT;
 477                         if (f != 0 &&
 478                             !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)) {
 479                                 unlock_page(page);
 480                                 break;
 481                         }
 482                         to = t;
 483
 484                         trace_afs_page_dirty(vnode, tracepoint_string("store+"),
 485                                              page->index, priv);
 486
 487                         if (!clear_page_dirty_for_io(page))
 488                                 BUG();
 489                         if (test_set_page_writeback(page))
 490                                 BUG();
 491                         unlock_page(page);
 492                         put_page(page);
 493                 }
 494                 count += loop;
 495                 if (loop < n) {
 496                         for (; loop < n; loop++)
 497                                 put_page(pages[loop]);
 498                         goto no_more;
 499                 }
 500
 501                 start += loop;
 502         } while (start <= final_page && count < 65536);
 503
 504 no_more:
 505         /* We now have a contiguous set of dirty pages, each with writeback
 506          * set; the first page is still locked at this point, but all the rest
 507          * have been unlocked.
 508          */
 509         unlock_page(primary_page);
 510
 511         first = primary_page->index;
 512         last = first + count - 1;
 513
 514         _debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
 515
 516         ret = afs_store_data(mapping, first, last, offset, to);
 517         switch (ret) {
 518         case 0:
 519                 ret = count;
 520                 break;
 521
 522         default:
 523                 pr_notice("kAFS: Unexpected error from FS.StoreData %d\n", ret);
 524                 /* Fall through */
 525         case -EACCES:
 526         case -EPERM:
 527         case -ENOKEY:
 528         case -EKEYEXPIRED:
 529         case -EKEYREJECTED:
 530         case -EKEYREVOKED:
 531                 afs_redirty_pages(wbc, mapping, first, last);
 532                 mapping_set_error(mapping, ret);
 533                 break;
 534
 535         case -EDQUOT:
 536         case -ENOSPC:
 537                 afs_redirty_pages(wbc, mapping, first, last);
 538                 mapping_set_error(mapping, -ENOSPC);
 539                 break;
 540
 541         case -EROFS:
 542         case -EIO:
 543         case -EREMOTEIO:
 544         case -EFBIG:
 545         case -ENOENT:
 546         case -ENOMEDIUM:
 547         case -ENXIO:
 548                 trace_afs_file_error(vnode, ret, afs_file_error_writeback_fail);
 549                 afs_kill_pages(mapping, first, last);
 550                 mapping_set_error(mapping, ret);
 551                 break;
 552         }
 553
 554         _leave(" = %d", ret);
 555         return ret;
 556 }
 557
 558 /*
 559  * write a page back to the server
 560  * - the caller locked the page for us
 561  */
 562 int afs_writepage(struct page *page, struct writeback_control *wbc)
 563 {
 564         int ret;
 565
 566         _enter("{%lx},", page->index);
 567
 568         ret = afs_write_back_from_locked_page(page->mapping, wbc, page,
 569                                               wbc->range_end >> PAGE_SHIFT);
 570         if (ret < 0) {
 571                 _leave(" = %d", ret);
 572                 return 0;
 573         }
 574
 575         wbc->nr_to_write -= ret;
 576
 577         _leave(" = 0");
 578         return 0;
 579 }
 580
 581 /*
 582  * write a region of pages back to the server
 583  */
 584 static int afs_writepages_region(struct address_space *mapping,
 585                                  struct writeback_control *wbc,
 586                                  pgoff_t index, pgoff_t end, pgoff_t *_next)
 587 {
 588         struct page *page;
 589         int ret, n;
 590
 591         _enter(",,%lx,%lx,", index, end);
 592
 593         do {
 594                 n = find_get_pages_range_tag(mapping, &index, end,
 595                                         PAGECACHE_TAG_DIRTY, 1, &page);
 596                 if (!n)
 597                         break;
 598
 599                 _debug("wback %lx", page->index);
 600
 601                 /*
 602                  * at this point we hold neither the i_pages lock nor the
 603                  * page lock: the page may be truncated or invalidated
 604                  * (changing page->mapping to NULL), or even swizzled
 605                  * back from swapper_space to tmpfs file mapping
 606                  */
 607                 ret = lock_page_killable(page);
 608                 if (ret < 0) {
 609                         put_page(page);
 610                         _leave(" = %d", ret);
 611                         return ret;
 612                 }
 613
 614                 if (page->mapping != mapping || !PageDirty(page)) {
 615                         unlock_page(page);
 616                         put_page(page);
 617                         continue;
 618                 }
 619
 620                 if (PageWriteback(page)) {
 621                         unlock_page(page);
 622                         if (wbc->sync_mode != WB_SYNC_NONE)
 623                                 wait_on_page_writeback(page);
 624                         put_page(page);
 625                         continue;
 626                 }
 627
 628                 if (!clear_page_dirty_for_io(page))
 629                         BUG();
 630                 ret = afs_write_back_from_locked_page(mapping, wbc, page, end);
 631                 put_page(page);
 632                 if (ret < 0) {
 633                         _leave(" = %d", ret);
 634                         return ret;
 635                 }
 636
 637                 wbc->nr_to_write -= ret;
 638
 639                 cond_resched();
 640         } while (index < end && wbc->nr_to_write > 0);
 641
 642         *_next = index;
 643         _leave(" = 0 [%lx]", *_next);
 644         return 0;
 645 }
 646
 647 /*
 648  * write some of the pending data back to the server
 649  */
 650 int afs_writepages(struct address_space *mapping,
 651                    struct writeback_control *wbc)
 652 {
 653         pgoff_t start, end, next;
 654         int ret;
 655
 656         _enter("");
 657
 658         if (wbc->range_cyclic) {
 659                 start = mapping->writeback_index;
 660                 end = -1;
 661                 ret = afs_writepages_region(mapping, wbc, start, end, &next);
 662                 if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
 663                         ret = afs_writepages_region(mapping, wbc, 0, start,
 664                                                     &next);
 665                 mapping->writeback_index = next;
 666         } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
 667                 end = (pgoff_t)(LLONG_MAX >> PAGE_SHIFT);
 668                 ret = afs_writepages_region(mapping, wbc, 0, end, &next);
 669                 if (wbc->nr_to_write > 0)
 670                         mapping->writeback_index = next;
 671         } else {
 672                 start = wbc->range_start >> PAGE_SHIFT;
 673                 end = wbc->range_end >> PAGE_SHIFT;
 674                 ret = afs_writepages_region(mapping, wbc, start, end, &next);
 675         }
 676
 677         _leave(" = %d", ret);
 678         return ret;
 679 }
 680
 681 /*
 682  * completion of write to server
 683  */
 684 void afs_pages_written_back(struct afs_vnode *vnode, struct afs_call *call)
 685 {
 686         struct pagevec pv;
 687         unsigned long priv;
 688         unsigned count, loop;
 689         pgoff_t first = call->first, last = call->last;
 690
 691         _enter("{%llx:%llu},{%lx-%lx}",
 692                vnode->fid.vid, vnode->fid.vnode, first, last);
 693
 694         pagevec_init(&pv);
 695
 696         do {
 697                 _debug("done %lx-%lx", first, last);
 698
 699                 count = last - first + 1;
 700                 if (count > PAGEVEC_SIZE)
 701                         count = PAGEVEC_SIZE;
 702                 pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
 703                                               first, count, pv.pages);
 704                 ASSERTCMP(pv.nr, ==, count);
 705
 706                 for (loop = 0; loop < count; loop++) {
 707                         priv = page_private(pv.pages[loop]);
 708                         trace_afs_page_dirty(vnode, tracepoint_string("clear"),
 709                                              pv.pages[loop]->index, priv);
 710                         set_page_private(pv.pages[loop], 0);
 711                         end_page_writeback(pv.pages[loop]);
 712                 }
 713                 first += count;
 714                 __pagevec_release(&pv);
 715         } while (first <= last);
 716
 717         afs_prune_wb_keys(vnode);
 718         _leave("");
 719 }
 720
 721 /*
 722  * write to an AFS file
 723  */
 724 ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
 725 {
 726         struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
 727         ssize_t result;
 728         size_t count = iov_iter_count(from);
 729
 730         _enter("{%llx:%llu},{%zu},",
 731                vnode->fid.vid, vnode->fid.vnode, count);
 732
 733         if (IS_SWAPFILE(&vnode->vfs_inode)) {
 734                 printk(KERN_INFO
 735                        "AFS: Attempt to write to active swap file!\n");
 736                 return -EBUSY;
 737         }
 738
 739         if (!count)
 740                 return 0;
 741
 742         result = generic_file_write_iter(iocb, from);
 743
 744         _leave(" = %zd", result);
 745         return result;
 746 }
 747
 748 /*
 749  * flush any dirty pages for this process, and check for write errors.
 750  * - the return status from this call provides a reliable indication of
 751  *   whether any write errors occurred for this process.
 752  */
 753 int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 754 {
 755         struct inode *inode = file_inode(file);
 756         struct afs_vnode *vnode = AFS_FS_I(inode);
 757
 758         _enter("{%llx:%llu},{n=%pD},%d",
 759                vnode->fid.vid, vnode->fid.vnode, file,
 760                datasync);
 761
 762         return file_write_and_wait_range(file, start, end);
 763 }
 764
 765 /*
 766  * notification that a previously read-only page is about to become writable
 767  * - if it returns an error, the caller will deliver a bus error signal
 768  */
 769 vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
 770 {
 771         struct file *file = vmf->vma->vm_file;
 772         struct inode *inode = file_inode(file);
 773         struct afs_vnode *vnode = AFS_FS_I(inode);
 774         unsigned long priv;
 775
 776         _enter("{{%llx:%llu}},{%lx}",
 777                vnode->fid.vid, vnode->fid.vnode, vmf->page->index);
 778
 779         sb_start_pagefault(inode->i_sb);
 780
 781         /* Wait for the page to be written to the cache before we allow it to
 782          * be modified.  We then assume the entire page will need writing back.
 783          */
 784 #ifdef CONFIG_AFS_FSCACHE
 785         fscache_wait_on_page_write(vnode->cache, vmf->page);
 786 #endif
 787
 788         if (PageWriteback(vmf->page) &&
 789             wait_on_page_bit_killable(vmf->page, PG_writeback) < 0)
 790                 return VM_FAULT_RETRY;
 791
 792         if (lock_page_killable(vmf->page) < 0)
 793                 return VM_FAULT_RETRY;
 794
 795         /* We mustn't change page->private until writeback is complete as that
 796          * details the portion of the page we need to write back and we might
 797          * need to redirty the page if there's a problem.
 798          */
 799         wait_on_page_writeback(vmf->page);
 800
 801         priv = (unsigned long)PAGE_SIZE << AFS_PRIV_SHIFT; /* To */
 802         priv |= 0; /* From */
 803         trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"),
 804                              vmf->page->index, priv);
 805         SetPagePrivate(vmf->page);
 806         set_page_private(vmf->page, priv);
 807
 808         sb_end_pagefault(inode->i_sb);
 809         return VM_FAULT_LOCKED;
 810 }
 811
 812 /*
 813  * Prune the keys cached for writeback.  The caller must hold vnode->wb_lock.
 814  */
 815 void afs_prune_wb_keys(struct afs_vnode *vnode)
 816 {
 817         LIST_HEAD(graveyard);
 818         struct afs_wb_key *wbk, *tmp;
 819
 820         /* Discard unused keys */
 821         spin_lock(&vnode->wb_lock);
 822
 823         if (!mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
 824             !mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_DIRTY)) {
 825                 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
 826                         if (refcount_read(&wbk->usage) == 1)
 827                                 list_move(&wbk->vnode_link, &graveyard);
 828                 }
 829         }
 830
 831         spin_unlock(&vnode->wb_lock);
 832
 833         while (!list_empty(&graveyard)) {
 834                 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
 835                 list_del(&wbk->vnode_link);
 836                 afs_put_wb_key(wbk);
 837         }
 838 }
 839
 840 /*
 841  * Clean up a page during invalidation.
 842  */
 843 int afs_launder_page(struct page *page)
 844 {
 845         struct address_space *mapping = page->mapping;
 846         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 847         unsigned long priv;
 848         unsigned int f, t;
 849         int ret = 0;
 850
 851         _enter("{%lx}", page->index);
 852
 853         priv = page_private(page);
 854         if (clear_page_dirty_for_io(page)) {
 855                 f = 0;
 856                 t = PAGE_SIZE;
 857                 if (PagePrivate(page)) {
 858                         f = priv & AFS_PRIV_MAX;
 859                         t = priv >> AFS_PRIV_SHIFT;
 860                 }
 861
 862                 trace_afs_page_dirty(vnode, tracepoint_string("launder"),
 863                                      page->index, priv);
 864                 ret = afs_store_data(mapping, page->index, page->index, t, f);
 865         }
 866
 867         trace_afs_page_dirty(vnode, tracepoint_string("laundered"),
 868                              page->index, priv);
 869         set_page_private(page, 0);
 870         ClearPagePrivate(page);
 871
 872 #ifdef CONFIG_AFS_FSCACHE
 873         if (PageFsCache(page)) {
 874                 fscache_wait_on_page_write(vnode->cache, page);
 875                 fscache_uncache_page(vnode->cache, page);
 876         }
 877 #endif
 878         return ret;
 879 }