fs/afs/write.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* handling of writes to regular files and writing back to the server
   3  *
   4  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #include <linux/backing-dev.h>
   9 #include <linux/slab.h>
  10 #include <linux/fs.h>
  11 #include <linux/pagemap.h>
  12 #include <linux/writeback.h>
  13 #include <linux/pagevec.h>
  14 #include "internal.h"
  15
  16 /*
  17  * mark a page as having been made dirty and thus needing writeback
  18  */
  19 int afs_set_page_dirty(struct page *page)
  20 {
  21         _enter("");
  22         return __set_page_dirty_nobuffers(page);
  23 }
  24
  25 /*
  26  * partly or wholly fill a page that's under preparation for writing
  27  */
  28 static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
  29                          loff_t pos, unsigned int len, struct page *page)
  30 {
  31         struct afs_read *req;
  32         size_t p;
  33         void *data;
  34         int ret;
  35
  36         _enter(",,%llu", (unsigned long long)pos);
  37
  38         if (pos >= vnode->vfs_inode.i_size) {
  39                 p = pos & ~PAGE_MASK;
  40                 ASSERTCMP(p + len, <=, PAGE_SIZE);
  41                 data = kmap(page);
  42                 memset(data + p, 0, len);
  43                 kunmap(page);
  44                 return 0;
  45         }
  46
  47         req = kzalloc(sizeof(struct afs_read) + sizeof(struct page *),
  48                       GFP_KERNEL);
  49         if (!req)
  50                 return -ENOMEM;
  51
  52         refcount_set(&req->usage, 1);
  53         req->pos = pos;
  54         req->len = len;
  55         req->nr_pages = 1;
  56         req->pages = req->array;
  57         req->pages[0] = page;
  58         get_page(page);
  59
  60         ret = afs_fetch_data(vnode, key, req);
  61         afs_put_read(req);
  62         if (ret < 0) {
  63                 if (ret == -ENOENT) {
  64                         _debug("got NOENT from server"
  65                                " - marking file deleted and stale");
  66                         set_bit(AFS_VNODE_DELETED, &vnode->flags);
  67                         ret = -ESTALE;
  68                 }
  69         }
  70
  71         _leave(" = %d", ret);
  72         return ret;
  73 }
  74
  75 /*
  76  * prepare to perform part of a write to a page
  77  */
  78 int afs_write_begin(struct file *file, struct address_space *mapping,
  79                     loff_t pos, unsigned len, unsigned flags,
  80                     struct page **pagep, void **fsdata)
  81 {
  82         struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
  83         struct page *page;
  84         struct key *key = afs_file_key(file);
  85         unsigned long priv;
  86         unsigned f, from = pos & (PAGE_SIZE - 1);
  87         unsigned t, to = from + len;
  88         pgoff_t index = pos >> PAGE_SHIFT;
  89         int ret;
  90
  91         _enter("{%llx:%llu},{%lx},%u,%u",
  92                vnode->fid.vid, vnode->fid.vnode, index, from, to);
  93
  94         /* We want to store information about how much of a page is altered in
  95          * page->private.
  96          */
  97         BUILD_BUG_ON(PAGE_SIZE > 32768 && sizeof(page->private) < 8);
  98
  99         page = grab_cache_page_write_begin(mapping, index, flags);
 100         if (!page)
 101                 return -ENOMEM;
 102
 103         if (!PageUptodate(page) && len != PAGE_SIZE) {
 104                 ret = afs_fill_page(vnode, key, pos & PAGE_MASK, PAGE_SIZE, page);
 105                 if (ret < 0) {
 106                         unlock_page(page);
 107                         put_page(page);
 108                         _leave(" = %d [prep]", ret);
 109                         return ret;
 110                 }
 111                 SetPageUptodate(page);
 112         }
 113
 114         /* page won't leak in error case: it eventually gets cleaned off LRU */
 115         *pagep = page;
 116
 117 try_again:
 118         /* See if this page is already partially written in a way that we can
 119          * merge the new write with.
 120          */
 121         t = f = 0;
 122         if (PagePrivate(page)) {
 123                 priv = page_private(page);
 124                 f = priv & AFS_PRIV_MAX;
 125                 t = priv >> AFS_PRIV_SHIFT;
 126                 ASSERTCMP(f, <=, t);
 127         }
 128
 129         if (f != t) {
 130                 if (PageWriteback(page)) {
 131                         trace_afs_page_dirty(vnode, tracepoint_string("alrdy"),
 132                                              page->index, priv);
 133                         goto flush_conflicting_write;
 134                 }
 135                 /* If the file is being filled locally, allow inter-write
 136                  * spaces to be merged into writes.  If it's not, only write
 137                  * back what the user gives us.
 138                  */
 139                 if (!test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags) &&
 140                     (to < f || from > t))
 141                         goto flush_conflicting_write;
 142                 if (from < f)
 143                         f = from;
 144                 if (to > t)
 145                         t = to;
 146         } else {
 147                 f = from;
 148                 t = to;
 149         }
 150
 151         priv = (unsigned long)t << AFS_PRIV_SHIFT;
 152         priv |= f;
 153         trace_afs_page_dirty(vnode, tracepoint_string("begin"),
 154                              page->index, priv);
 155         SetPagePrivate(page);
 156         set_page_private(page, priv);
 157         _leave(" = 0");
 158         return 0;
 159
 160         /* The previous write and this write aren't adjacent or overlapping, so
 161          * flush the page out.
 162          */
 163 flush_conflicting_write:
 164         _debug("flush conflict");
 165         ret = write_one_page(page);
 166         if (ret < 0) {
 167                 _leave(" = %d", ret);
 168                 return ret;
 169         }
 170
 171         ret = lock_page_killable(page);
 172         if (ret < 0) {
 173                 _leave(" = %d", ret);
 174                 return ret;
 175         }
 176         goto try_again;
 177 }
 178
 179 /*
 180  * finalise part of a write to a page
 181  */
 182 int afs_write_end(struct file *file, struct address_space *mapping,
 183                   loff_t pos, unsigned len, unsigned copied,
 184                   struct page *page, void *fsdata)
 185 {
 186         struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
 187         struct key *key = afs_file_key(file);
 188         loff_t i_size, maybe_i_size;
 189         int ret;
 190
 191         _enter("{%llx:%llu},{%lx}",
 192                vnode->fid.vid, vnode->fid.vnode, page->index);
 193
 194         maybe_i_size = pos + copied;
 195
 196         i_size = i_size_read(&vnode->vfs_inode);
 197         if (maybe_i_size > i_size) {
 198                 spin_lock(&vnode->wb_lock);
 199                 i_size = i_size_read(&vnode->vfs_inode);
 200                 if (maybe_i_size > i_size)
 201                         i_size_write(&vnode->vfs_inode, maybe_i_size);
 202                 spin_unlock(&vnode->wb_lock);
 203         }
 204
 205         if (!PageUptodate(page)) {
 206                 if (copied < len) {
 207                         /* Try and load any missing data from the server.  The
 208                          * unmarshalling routine will take care of clearing any
 209                          * bits that are beyond the EOF.
 210                          */
 211                         ret = afs_fill_page(vnode, key, pos + copied,
 212                                             len - copied, page);
 213                         if (ret < 0)
 214                                 goto out;
 215                 }
 216                 SetPageUptodate(page);
 217         }
 218
 219         set_page_dirty(page);
 220         if (PageDirty(page))
 221                 _debug("dirtied");
 222         ret = copied;
 223
 224 out:
 225         unlock_page(page);
 226         put_page(page);
 227         return ret;
 228 }
 229
 230 /*
 231  * kill all the pages in the given range
 232  */
 233 static void afs_kill_pages(struct address_space *mapping,
 234                            pgoff_t first, pgoff_t last)
 235 {
 236         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 237         struct pagevec pv;
 238         unsigned count, loop;
 239
 240         _enter("{%llx:%llu},%lx-%lx",
 241                vnode->fid.vid, vnode->fid.vnode, first, last);
 242
 243         pagevec_init(&pv);
 244
 245         do {
 246                 _debug("kill %lx-%lx", first, last);
 247
 248                 count = last - first + 1;
 249                 if (count > PAGEVEC_SIZE)
 250                         count = PAGEVEC_SIZE;
 251                 pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
 252                 ASSERTCMP(pv.nr, ==, count);
 253
 254                 for (loop = 0; loop < count; loop++) {
 255                         struct page *page = pv.pages[loop];
 256                         ClearPageUptodate(page);
 257                         SetPageError(page);
 258                         end_page_writeback(page);
 259                         if (page->index >= first)
 260                                 first = page->index + 1;
 261                         lock_page(page);
 262                         generic_error_remove_page(mapping, page);
 263                         unlock_page(page);
 264                 }
 265
 266                 __pagevec_release(&pv);
 267         } while (first <= last);
 268
 269         _leave("");
 270 }
 271
 272 /*
 273  * Redirty all the pages in a given range.
 274  */
 275 static void afs_redirty_pages(struct writeback_control *wbc,
 276                               struct address_space *mapping,
 277                               pgoff_t first, pgoff_t last)
 278 {
 279         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 280         struct pagevec pv;
 281         unsigned count, loop;
 282
 283         _enter("{%llx:%llu},%lx-%lx",
 284                vnode->fid.vid, vnode->fid.vnode, first, last);
 285
 286         pagevec_init(&pv);
 287
 288         do {
 289                 _debug("redirty %lx-%lx", first, last);
 290
 291                 count = last - first + 1;
 292                 if (count > PAGEVEC_SIZE)
 293                         count = PAGEVEC_SIZE;
 294                 pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
 295                 ASSERTCMP(pv.nr, ==, count);
 296
 297                 for (loop = 0; loop < count; loop++) {
 298                         struct page *page = pv.pages[loop];
 299
 300                         redirty_page_for_writepage(wbc, page);
 301                         end_page_writeback(page);
 302                         if (page->index >= first)
 303                                 first = page->index + 1;
 304                 }
 305
 306                 __pagevec_release(&pv);
 307         } while (first <= last);
 308
 309         _leave("");
 310 }
 311
 312 /*
 313  * completion of write to server
 314  */
 315 static void afs_pages_written_back(struct afs_vnode *vnode,
 316                                    pgoff_t first, pgoff_t last)
 317 {
 318         struct pagevec pv;
 319         unsigned long priv;
 320         unsigned count, loop;
 321
 322         _enter("{%llx:%llu},{%lx-%lx}",
 323                vnode->fid.vid, vnode->fid.vnode, first, last);
 324
 325         pagevec_init(&pv);
 326
 327         do {
 328                 _debug("done %lx-%lx", first, last);
 329
 330                 count = last - first + 1;
 331                 if (count > PAGEVEC_SIZE)
 332                         count = PAGEVEC_SIZE;
 333                 pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
 334                                               first, count, pv.pages);
 335                 ASSERTCMP(pv.nr, ==, count);
 336
 337                 for (loop = 0; loop < count; loop++) {
 338                         priv = page_private(pv.pages[loop]);
 339                         trace_afs_page_dirty(vnode, tracepoint_string("clear"),
 340                                              pv.pages[loop]->index, priv);
 341                         set_page_private(pv.pages[loop], 0);
 342                         end_page_writeback(pv.pages[loop]);
 343                 }
 344                 first += count;
 345                 __pagevec_release(&pv);
 346         } while (first <= last);
 347
 348         afs_prune_wb_keys(vnode);
 349         _leave("");
 350 }
 351
 352 /*
 353  * write to a file
 354  */
 355 static int afs_store_data(struct address_space *mapping,
 356                           pgoff_t first, pgoff_t last,
 357                           unsigned offset, unsigned to)
 358 {
 359         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 360         struct afs_fs_cursor fc;
 361         struct afs_status_cb *scb;
 362         struct afs_wb_key *wbk = NULL;
 363         struct list_head *p;
 364         int ret = -ENOKEY, ret2;
 365
 366         _enter("%s{%llx:%llu.%u},%lx,%lx,%x,%x",
 367                vnode->volume->name,
 368                vnode->fid.vid,
 369                vnode->fid.vnode,
 370                vnode->fid.unique,
 371                first, last, offset, to);
 372
 373         scb = kzalloc(sizeof(struct afs_status_cb), GFP_NOFS);
 374         if (!scb)
 375                 return -ENOMEM;
 376
 377         spin_lock(&vnode->wb_lock);
 378         p = vnode->wb_keys.next;
 379
 380         /* Iterate through the list looking for a valid key to use. */
 381 try_next_key:
 382         while (p != &vnode->wb_keys) {
 383                 wbk = list_entry(p, struct afs_wb_key, vnode_link);
 384                 _debug("wbk %u", key_serial(wbk->key));
 385                 ret2 = key_validate(wbk->key);
 386                 if (ret2 == 0)
 387                         goto found_key;
 388                 if (ret == -ENOKEY)
 389                         ret = ret2;
 390                 p = p->next;
 391         }
 392
 393         spin_unlock(&vnode->wb_lock);
 394         afs_put_wb_key(wbk);
 395         kfree(scb);
 396         _leave(" = %d [no keys]", ret);
 397         return ret;
 398
 399 found_key:
 400         refcount_inc(&wbk->usage);
 401         spin_unlock(&vnode->wb_lock);
 402
 403         _debug("USE WB KEY %u", key_serial(wbk->key));
 404
 405         ret = -ERESTARTSYS;
 406         if (afs_begin_vnode_operation(&fc, vnode, wbk->key, false)) {
 407                 afs_dataversion_t data_version = vnode->status.data_version + 1;
 408
 409                 while (afs_select_fileserver(&fc)) {
 410                         fc.cb_break = afs_calc_vnode_cb_break(vnode);
 411                         afs_fs_store_data(&fc, mapping, first, last, offset, to, scb);
 412                 }
 413
 414                 afs_check_for_remote_deletion(&fc, vnode);
 415                 afs_vnode_commit_status(&fc, vnode, fc.cb_break,
 416                                         &data_version, scb);
 417                 if (fc.ac.error == 0)
 418                         afs_pages_written_back(vnode, first, last);
 419                 ret = afs_end_vnode_operation(&fc);
 420         }
 421
 422         switch (ret) {
 423         case 0:
 424                 afs_stat_v(vnode, n_stores);
 425                 atomic_long_add((last * PAGE_SIZE + to) -
 426                                 (first * PAGE_SIZE + offset),
 427                                 &afs_v2net(vnode)->n_store_bytes);
 428                 break;
 429         case -EACCES:
 430         case -EPERM:
 431         case -ENOKEY:
 432         case -EKEYEXPIRED:
 433         case -EKEYREJECTED:
 434         case -EKEYREVOKED:
 435                 _debug("next");
 436                 spin_lock(&vnode->wb_lock);
 437                 p = wbk->vnode_link.next;
 438                 afs_put_wb_key(wbk);
 439                 goto try_next_key;
 440         }
 441
 442         afs_put_wb_key(wbk);
 443         kfree(scb);
 444         _leave(" = %d", ret);
 445         return ret;
 446 }
 447
 448 /*
 449  * Synchronously write back the locked page and any subsequent non-locked dirty
 450  * pages.
 451  */
 452 static int afs_write_back_from_locked_page(struct address_space *mapping,
 453                                            struct writeback_control *wbc,
 454                                            struct page *primary_page,
 455                                            pgoff_t final_page)
 456 {
 457         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 458         struct page *pages[8], *page;
 459         unsigned long count, priv;
 460         unsigned n, offset, to, f, t;
 461         pgoff_t start, first, last;
 462         int loop, ret;
 463
 464         _enter(",%lx", primary_page->index);
 465
 466         count = 1;
 467         if (test_set_page_writeback(primary_page))
 468                 BUG();
 469
 470         /* Find all consecutive lockable dirty pages that have contiguous
 471          * written regions, stopping when we find a page that is not
 472          * immediately lockable, is not dirty or is missing, or we reach the
 473          * end of the range.
 474          */
 475         start = primary_page->index;
 476         priv = page_private(primary_page);
 477         offset = priv & AFS_PRIV_MAX;
 478         to = priv >> AFS_PRIV_SHIFT;
 479         trace_afs_page_dirty(vnode, tracepoint_string("store"),
 480                              primary_page->index, priv);
 481
 482         WARN_ON(offset == to);
 483         if (offset == to)
 484                 trace_afs_page_dirty(vnode, tracepoint_string("WARN"),
 485                                      primary_page->index, priv);
 486
 487         if (start >= final_page ||
 488             (to < PAGE_SIZE && !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)))
 489                 goto no_more;
 490
 491         start++;
 492         do {
 493                 _debug("more %lx [%lx]", start, count);
 494                 n = final_page - start + 1;
 495                 if (n > ARRAY_SIZE(pages))
 496                         n = ARRAY_SIZE(pages);
 497                 n = find_get_pages_contig(mapping, start, ARRAY_SIZE(pages), pages);
 498                 _debug("fgpc %u", n);
 499                 if (n == 0)
 500                         goto no_more;
 501                 if (pages[0]->index != start) {
 502                         do {
 503                                 put_page(pages[--n]);
 504                         } while (n > 0);
 505                         goto no_more;
 506                 }
 507
 508                 for (loop = 0; loop < n; loop++) {
 509                         page = pages[loop];
 510                         if (to != PAGE_SIZE &&
 511                             !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags))
 512                                 break;
 513                         if (page->index > final_page)
 514                                 break;
 515                         if (!trylock_page(page))
 516                                 break;
 517                         if (!PageDirty(page) || PageWriteback(page)) {
 518                                 unlock_page(page);
 519                                 break;
 520                         }
 521
 522                         priv = page_private(page);
 523                         f = priv & AFS_PRIV_MAX;
 524                         t = priv >> AFS_PRIV_SHIFT;
 525                         if (f != 0 &&
 526                             !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)) {
 527                                 unlock_page(page);
 528                                 break;
 529                         }
 530                         to = t;
 531
 532                         trace_afs_page_dirty(vnode, tracepoint_string("store+"),
 533                                              page->index, priv);
 534
 535                         if (!clear_page_dirty_for_io(page))
 536                                 BUG();
 537                         if (test_set_page_writeback(page))
 538                                 BUG();
 539                         unlock_page(page);
 540                         put_page(page);
 541                 }
 542                 count += loop;
 543                 if (loop < n) {
 544                         for (; loop < n; loop++)
 545                                 put_page(pages[loop]);
 546                         goto no_more;
 547                 }
 548
 549                 start += loop;
 550         } while (start <= final_page && count < 65536);
 551
 552 no_more:
 553         /* We now have a contiguous set of dirty pages, each with writeback
 554          * set; the first page is still locked at this point, but all the rest
 555          * have been unlocked.
 556          */
 557         unlock_page(primary_page);
 558
 559         first = primary_page->index;
 560         last = first + count - 1;
 561
 562         _debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
 563
 564         ret = afs_store_data(mapping, first, last, offset, to);
 565         switch (ret) {
 566         case 0:
 567                 ret = count;
 568                 break;
 569
 570         default:
 571                 pr_notice("kAFS: Unexpected error from FS.StoreData %d\n", ret);
 572                 /* Fall through */
 573         case -EACCES:
 574         case -EPERM:
 575         case -ENOKEY:
 576         case -EKEYEXPIRED:
 577         case -EKEYREJECTED:
 578         case -EKEYREVOKED:
 579                 afs_redirty_pages(wbc, mapping, first, last);
 580                 mapping_set_error(mapping, ret);
 581                 break;
 582
 583         case -EDQUOT:
 584         case -ENOSPC:
 585                 afs_redirty_pages(wbc, mapping, first, last);
 586                 mapping_set_error(mapping, -ENOSPC);
 587                 break;
 588
 589         case -EROFS:
 590         case -EIO:
 591         case -EREMOTEIO:
 592         case -EFBIG:
 593         case -ENOENT:
 594         case -ENOMEDIUM:
 595         case -ENXIO:
 596                 trace_afs_file_error(vnode, ret, afs_file_error_writeback_fail);
 597                 afs_kill_pages(mapping, first, last);
 598                 mapping_set_error(mapping, ret);
 599                 break;
 600         }
 601
 602         _leave(" = %d", ret);
 603         return ret;
 604 }
 605
 606 /*
 607  * write a page back to the server
 608  * - the caller locked the page for us
 609  */
 610 int afs_writepage(struct page *page, struct writeback_control *wbc)
 611 {
 612         int ret;
 613
 614         _enter("{%lx},", page->index);
 615
 616         ret = afs_write_back_from_locked_page(page->mapping, wbc, page,
 617                                               wbc->range_end >> PAGE_SHIFT);
 618         if (ret < 0) {
 619                 _leave(" = %d", ret);
 620                 return 0;
 621         }
 622
 623         wbc->nr_to_write -= ret;
 624
 625         _leave(" = 0");
 626         return 0;
 627 }
 628
 629 /*
 630  * write a region of pages back to the server
 631  */
 632 static int afs_writepages_region(struct address_space *mapping,
 633                                  struct writeback_control *wbc,
 634                                  pgoff_t index, pgoff_t end, pgoff_t *_next)
 635 {
 636         struct page *page;
 637         int ret, n;
 638
 639         _enter(",,%lx,%lx,", index, end);
 640
 641         do {
 642                 n = find_get_pages_range_tag(mapping, &index, end,
 643                                         PAGECACHE_TAG_DIRTY, 1, &page);
 644                 if (!n)
 645                         break;
 646
 647                 _debug("wback %lx", page->index);
 648
 649                 /*
 650                  * at this point we hold neither the i_pages lock nor the
 651                  * page lock: the page may be truncated or invalidated
 652                  * (changing page->mapping to NULL), or even swizzled
 653                  * back from swapper_space to tmpfs file mapping
 654                  */
 655                 ret = lock_page_killable(page);
 656                 if (ret < 0) {
 657                         put_page(page);
 658                         _leave(" = %d", ret);
 659                         return ret;
 660                 }
 661
 662                 if (page->mapping != mapping || !PageDirty(page)) {
 663                         unlock_page(page);
 664                         put_page(page);
 665                         continue;
 666                 }
 667
 668                 if (PageWriteback(page)) {
 669                         unlock_page(page);
 670                         if (wbc->sync_mode != WB_SYNC_NONE)
 671                                 wait_on_page_writeback(page);
 672                         put_page(page);
 673                         continue;
 674                 }
 675
 676                 if (!clear_page_dirty_for_io(page))
 677                         BUG();
 678                 ret = afs_write_back_from_locked_page(mapping, wbc, page, end);
 679                 put_page(page);
 680                 if (ret < 0) {
 681                         _leave(" = %d", ret);
 682                         return ret;
 683                 }
 684
 685                 wbc->nr_to_write -= ret;
 686
 687                 cond_resched();
 688         } while (index < end && wbc->nr_to_write > 0);
 689
 690         *_next = index;
 691         _leave(" = 0 [%lx]", *_next);
 692         return 0;
 693 }
 694
 695 /*
 696  * write some of the pending data back to the server
 697  */
 698 int afs_writepages(struct address_space *mapping,
 699                    struct writeback_control *wbc)
 700 {
 701         pgoff_t start, end, next;
 702         int ret;
 703
 704         _enter("");
 705
 706         if (wbc->range_cyclic) {
 707                 start = mapping->writeback_index;
 708                 end = -1;
 709                 ret = afs_writepages_region(mapping, wbc, start, end, &next);
 710                 if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
 711                         ret = afs_writepages_region(mapping, wbc, 0, start,
 712                                                     &next);
 713                 mapping->writeback_index = next;
 714         } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
 715                 end = (pgoff_t)(LLONG_MAX >> PAGE_SHIFT);
 716                 ret = afs_writepages_region(mapping, wbc, 0, end, &next);
 717                 if (wbc->nr_to_write > 0)
 718                         mapping->writeback_index = next;
 719         } else {
 720                 start = wbc->range_start >> PAGE_SHIFT;
 721                 end = wbc->range_end >> PAGE_SHIFT;
 722                 ret = afs_writepages_region(mapping, wbc, start, end, &next);
 723         }
 724
 725         _leave(" = %d", ret);
 726         return ret;
 727 }
 728
 729 /*
 730  * write to an AFS file
 731  */
 732 ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
 733 {
 734         struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
 735         ssize_t result;
 736         size_t count = iov_iter_count(from);
 737
 738         _enter("{%llx:%llu},{%zu},",
 739                vnode->fid.vid, vnode->fid.vnode, count);
 740
 741         if (IS_SWAPFILE(&vnode->vfs_inode)) {
 742                 printk(KERN_INFO
 743                        "AFS: Attempt to write to active swap file!\n");
 744                 return -EBUSY;
 745         }
 746
 747         if (!count)
 748                 return 0;
 749
 750         result = generic_file_write_iter(iocb, from);
 751
 752         _leave(" = %zd", result);
 753         return result;
 754 }
 755
 756 /*
 757  * flush any dirty pages for this process, and check for write errors.
 758  * - the return status from this call provides a reliable indication of
 759  *   whether any write errors occurred for this process.
 760  */
 761 int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 762 {
 763         struct inode *inode = file_inode(file);
 764         struct afs_vnode *vnode = AFS_FS_I(inode);
 765
 766         _enter("{%llx:%llu},{n=%pD},%d",
 767                vnode->fid.vid, vnode->fid.vnode, file,
 768                datasync);
 769
 770         return file_write_and_wait_range(file, start, end);
 771 }
 772
 773 /*
 774  * notification that a previously read-only page is about to become writable
 775  * - if it returns an error, the caller will deliver a bus error signal
 776  */
 777 vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
 778 {
 779         struct file *file = vmf->vma->vm_file;
 780         struct inode *inode = file_inode(file);
 781         struct afs_vnode *vnode = AFS_FS_I(inode);
 782         unsigned long priv;
 783
 784         _enter("{{%llx:%llu}},{%lx}",
 785                vnode->fid.vid, vnode->fid.vnode, vmf->page->index);
 786
 787         sb_start_pagefault(inode->i_sb);
 788
 789         /* Wait for the page to be written to the cache before we allow it to
 790          * be modified.  We then assume the entire page will need writing back.
 791          */
 792 #ifdef CONFIG_AFS_FSCACHE
 793         fscache_wait_on_page_write(vnode->cache, vmf->page);
 794 #endif
 795
 796         if (PageWriteback(vmf->page) &&
 797             wait_on_page_bit_killable(vmf->page, PG_writeback) < 0)
 798                 return VM_FAULT_RETRY;
 799
 800         if (lock_page_killable(vmf->page) < 0)
 801                 return VM_FAULT_RETRY;
 802
 803         /* We mustn't change page->private until writeback is complete as that
 804          * details the portion of the page we need to write back and we might
 805          * need to redirty the page if there's a problem.
 806          */
 807         wait_on_page_writeback(vmf->page);
 808
 809         priv = (unsigned long)PAGE_SIZE << AFS_PRIV_SHIFT; /* To */
 810         priv |= 0; /* From */
 811         trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"),
 812                              vmf->page->index, priv);
 813         SetPagePrivate(vmf->page);
 814         set_page_private(vmf->page, priv);
 815
 816         sb_end_pagefault(inode->i_sb);
 817         return VM_FAULT_LOCKED;
 818 }
 819
 820 /*
 821  * Prune the keys cached for writeback.  The caller must hold vnode->wb_lock.
 822  */
 823 void afs_prune_wb_keys(struct afs_vnode *vnode)
 824 {
 825         LIST_HEAD(graveyard);
 826         struct afs_wb_key *wbk, *tmp;
 827
 828         /* Discard unused keys */
 829         spin_lock(&vnode->wb_lock);
 830
 831         if (!mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
 832             !mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_DIRTY)) {
 833                 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
 834                         if (refcount_read(&wbk->usage) == 1)
 835                                 list_move(&wbk->vnode_link, &graveyard);
 836                 }
 837         }
 838
 839         spin_unlock(&vnode->wb_lock);
 840
 841         while (!list_empty(&graveyard)) {
 842                 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
 843                 list_del(&wbk->vnode_link);
 844                 afs_put_wb_key(wbk);
 845         }
 846 }
 847
 848 /*
 849  * Clean up a page during invalidation.
 850  */
 851 int afs_launder_page(struct page *page)
 852 {
 853         struct address_space *mapping = page->mapping;
 854         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 855         unsigned long priv;
 856         unsigned int f, t;
 857         int ret = 0;
 858
 859         _enter("{%lx}", page->index);
 860
 861         priv = page_private(page);
 862         if (clear_page_dirty_for_io(page)) {
 863                 f = 0;
 864                 t = PAGE_SIZE;
 865                 if (PagePrivate(page)) {
 866                         f = priv & AFS_PRIV_MAX;
 867                         t = priv >> AFS_PRIV_SHIFT;
 868                 }
 869
 870                 trace_afs_page_dirty(vnode, tracepoint_string("launder"),
 871                                      page->index, priv);
 872                 ret = afs_store_data(mapping, page->index, page->index, t, f);
 873         }
 874
 875         trace_afs_page_dirty(vnode, tracepoint_string("laundered"),
 876                              page->index, priv);
 877         set_page_private(page, 0);
 878         ClearPagePrivate(page);
 879
 880 #ifdef CONFIG_AFS_FSCACHE
 881         if (PageFsCache(page)) {
 882                 fscache_wait_on_page_write(vnode->cache, page);
 883                 fscache_uncache_page(vnode->cache, page);
 884         }
 885 #endif
 886         return ret;
 887 }