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(struct_size(req, array, 1), GFP_KERNEL);
  48         if (!req)
  49                 return -ENOMEM;
  50
  51         refcount_set(&req->usage, 1);
  52         req->pos = pos;
  53         req->len = len;
  54         req->nr_pages = 1;
  55         req->pages = req->array;
  56         req->pages[0] = page;
  57         get_page(page);
  58
  59         ret = afs_fetch_data(vnode, key, req);
  60         afs_put_read(req);
  61         if (ret < 0) {
  62                 if (ret == -ENOENT) {
  63                         _debug("got NOENT from server"
  64                                " - marking file deleted and stale");
  65                         set_bit(AFS_VNODE_DELETED, &vnode->flags);
  66                         ret = -ESTALE;
  67                 }
  68         }
  69
  70         _leave(" = %d", ret);
  71         return ret;
  72 }
  73
  74 /*
  75  * prepare to perform part of a write to a page
  76  */
  77 int afs_write_begin(struct file *file, struct address_space *mapping,
  78                     loff_t pos, unsigned len, unsigned flags,
  79                     struct page **_page, void **fsdata)
  80 {
  81         struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
  82         struct page *page;
  83         struct key *key = afs_file_key(file);
  84         unsigned long priv;
  85         unsigned f, from = pos & (PAGE_SIZE - 1);
  86         unsigned t, to = from + len;
  87         pgoff_t index = pos >> PAGE_SHIFT;
  88         int ret;
  89
  90         _enter("{%llx:%llu},{%lx},%u,%u",
  91                vnode->fid.vid, vnode->fid.vnode, index, from, to);
  92
  93         page = grab_cache_page_write_begin(mapping, index, flags);
  94         if (!page)
  95                 return -ENOMEM;
  96
  97         if (!PageUptodate(page) && len != PAGE_SIZE) {
  98                 ret = afs_fill_page(vnode, key, pos & PAGE_MASK, PAGE_SIZE, page);
  99                 if (ret < 0) {
 100                         unlock_page(page);
 101                         put_page(page);
 102                         _leave(" = %d [prep]", ret);
 103                         return ret;
 104                 }
 105                 SetPageUptodate(page);
 106         }
 107
 108 try_again:
 109         /* See if this page is already partially written in a way that we can
 110          * merge the new write with.
 111          */
 112         t = f = 0;
 113         if (PagePrivate(page)) {
 114                 priv = page_private(page);
 115                 f = afs_page_dirty_from(priv);
 116                 t = afs_page_dirty_to(priv);
 117                 ASSERTCMP(f, <=, t);
 118         }
 119
 120         if (f != t) {
 121                 if (PageWriteback(page)) {
 122                         trace_afs_page_dirty(vnode, tracepoint_string("alrdy"),
 123                                              page->index, priv);
 124                         goto flush_conflicting_write;
 125                 }
 126                 /* If the file is being filled locally, allow inter-write
 127                  * spaces to be merged into writes.  If it's not, only write
 128                  * back what the user gives us.
 129                  */
 130                 if (!test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags) &&
 131                     (to < f || from > t))
 132                         goto flush_conflicting_write;
 133         }
 134
 135         *_page = page;
 136         _leave(" = 0");
 137         return 0;
 138
 139         /* The previous write and this write aren't adjacent or overlapping, so
 140          * flush the page out.
 141          */
 142 flush_conflicting_write:
 143         _debug("flush conflict");
 144         ret = write_one_page(page);
 145         if (ret < 0)
 146                 goto error;
 147
 148         ret = lock_page_killable(page);
 149         if (ret < 0)
 150                 goto error;
 151         goto try_again;
 152
 153 error:
 154         put_page(page);
 155         _leave(" = %d", ret);
 156         return ret;
 157 }
 158
 159 /*
 160  * finalise part of a write to a page
 161  */
 162 int afs_write_end(struct file *file, struct address_space *mapping,
 163                   loff_t pos, unsigned len, unsigned copied,
 164                   struct page *page, void *fsdata)
 165 {
 166         struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
 167         struct key *key = afs_file_key(file);
 168         unsigned long priv;
 169         unsigned int f, from = pos & (PAGE_SIZE - 1);
 170         unsigned int t, to = from + copied;
 171         loff_t i_size, maybe_i_size;
 172         int ret;
 173
 174         _enter("{%llx:%llu},{%lx}",
 175                vnode->fid.vid, vnode->fid.vnode, page->index);
 176
 177         maybe_i_size = pos + copied;
 178
 179         i_size = i_size_read(&vnode->vfs_inode);
 180         if (maybe_i_size > i_size) {
 181                 write_seqlock(&vnode->cb_lock);
 182                 i_size = i_size_read(&vnode->vfs_inode);
 183                 if (maybe_i_size > i_size)
 184                         i_size_write(&vnode->vfs_inode, maybe_i_size);
 185                 write_sequnlock(&vnode->cb_lock);
 186         }
 187
 188         if (!PageUptodate(page)) {
 189                 if (copied < len) {
 190                         /* Try and load any missing data from the server.  The
 191                          * unmarshalling routine will take care of clearing any
 192                          * bits that are beyond the EOF.
 193                          */
 194                         ret = afs_fill_page(vnode, key, pos + copied,
 195                                             len - copied, page);
 196                         if (ret < 0)
 197                                 goto out;
 198                 }
 199                 SetPageUptodate(page);
 200         }
 201
 202         if (PagePrivate(page)) {
 203                 priv = page_private(page);
 204                 f = afs_page_dirty_from(priv);
 205                 t = afs_page_dirty_to(priv);
 206                 if (from < f)
 207                         f = from;
 208                 if (to > t)
 209                         t = to;
 210                 priv = afs_page_dirty(f, t);
 211                 set_page_private(page, priv);
 212                 trace_afs_page_dirty(vnode, tracepoint_string("dirty+"),
 213                                      page->index, priv);
 214         } else {
 215                 priv = afs_page_dirty(from, to);
 216                 attach_page_private(page, (void *)priv);
 217                 trace_afs_page_dirty(vnode, tracepoint_string("dirty"),
 218                                      page->index, priv);
 219         }
 220
 221         set_page_dirty(page);
 222         if (PageDirty(page))
 223                 _debug("dirtied");
 224         ret = copied;
 225
 226 out:
 227         unlock_page(page);
 228         put_page(page);
 229         return ret;
 230 }
 231
 232 /*
 233  * kill all the pages in the given range
 234  */
 235 static void afs_kill_pages(struct address_space *mapping,
 236                            pgoff_t first, pgoff_t last)
 237 {
 238         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 239         struct pagevec pv;
 240         unsigned count, loop;
 241
 242         _enter("{%llx:%llu},%lx-%lx",
 243                vnode->fid.vid, vnode->fid.vnode, first, last);
 244
 245         pagevec_init(&pv);
 246
 247         do {
 248                 _debug("kill %lx-%lx", first, last);
 249
 250                 count = last - first + 1;
 251                 if (count > PAGEVEC_SIZE)
 252                         count = PAGEVEC_SIZE;
 253                 pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
 254                 ASSERTCMP(pv.nr, ==, count);
 255
 256                 for (loop = 0; loop < count; loop++) {
 257                         struct page *page = pv.pages[loop];
 258                         ClearPageUptodate(page);
 259                         SetPageError(page);
 260                         end_page_writeback(page);
 261                         if (page->index >= first)
 262                                 first = page->index + 1;
 263                         lock_page(page);
 264                         generic_error_remove_page(mapping, page);
 265                         unlock_page(page);
 266                 }
 267
 268                 __pagevec_release(&pv);
 269         } while (first <= last);
 270
 271         _leave("");
 272 }
 273
 274 /*
 275  * Redirty all the pages in a given range.
 276  */
 277 static void afs_redirty_pages(struct writeback_control *wbc,
 278                               struct address_space *mapping,
 279                               pgoff_t first, pgoff_t last)
 280 {
 281         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 282         struct pagevec pv;
 283         unsigned count, loop;
 284
 285         _enter("{%llx:%llu},%lx-%lx",
 286                vnode->fid.vid, vnode->fid.vnode, first, last);
 287
 288         pagevec_init(&pv);
 289
 290         do {
 291                 _debug("redirty %lx-%lx", first, last);
 292
 293                 count = last - first + 1;
 294                 if (count > PAGEVEC_SIZE)
 295                         count = PAGEVEC_SIZE;
 296                 pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
 297                 ASSERTCMP(pv.nr, ==, count);
 298
 299                 for (loop = 0; loop < count; loop++) {
 300                         struct page *page = pv.pages[loop];
 301
 302                         redirty_page_for_writepage(wbc, page);
 303                         end_page_writeback(page);
 304                         if (page->index >= first)
 305                                 first = page->index + 1;
 306                 }
 307
 308                 __pagevec_release(&pv);
 309         } while (first <= last);
 310
 311         _leave("");
 312 }
 313
 314 /*
 315  * completion of write to server
 316  */
 317 static void afs_pages_written_back(struct afs_vnode *vnode,
 318                                    pgoff_t first, pgoff_t last)
 319 {
 320         struct pagevec pv;
 321         unsigned long priv;
 322         unsigned count, loop;
 323
 324         _enter("{%llx:%llu},{%lx-%lx}",
 325                vnode->fid.vid, vnode->fid.vnode, first, last);
 326
 327         pagevec_init(&pv);
 328
 329         do {
 330                 _debug("done %lx-%lx", first, last);
 331
 332                 count = last - first + 1;
 333                 if (count > PAGEVEC_SIZE)
 334                         count = PAGEVEC_SIZE;
 335                 pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
 336                                               first, count, pv.pages);
 337                 ASSERTCMP(pv.nr, ==, count);
 338
 339                 for (loop = 0; loop < count; loop++) {
 340                         priv = (unsigned long)detach_page_private(pv.pages[loop]);
 341                         trace_afs_page_dirty(vnode, tracepoint_string("clear"),
 342                                              pv.pages[loop]->index, priv);
 343                         end_page_writeback(pv.pages[loop]);
 344                 }
 345                 first += count;
 346                 __pagevec_release(&pv);
 347         } while (first <= last);
 348
 349         afs_prune_wb_keys(vnode);
 350         _leave("");
 351 }
 352
 353 /*
 354  * Find a key to use for the writeback.  We cached the keys used to author the
 355  * writes on the vnode.  *_wbk will contain the last writeback key used or NULL
 356  * and we need to start from there if it's set.
 357  */
 358 static int afs_get_writeback_key(struct afs_vnode *vnode,
 359                                  struct afs_wb_key **_wbk)
 360 {
 361         struct afs_wb_key *wbk = NULL;
 362         struct list_head *p;
 363         int ret = -ENOKEY, ret2;
 364
 365         spin_lock(&vnode->wb_lock);
 366         if (*_wbk)
 367                 p = (*_wbk)->vnode_link.next;
 368         else
 369                 p = vnode->wb_keys.next;
 370
 371         while (p != &vnode->wb_keys) {
 372                 wbk = list_entry(p, struct afs_wb_key, vnode_link);
 373                 _debug("wbk %u", key_serial(wbk->key));
 374                 ret2 = key_validate(wbk->key);
 375                 if (ret2 == 0) {
 376                         refcount_inc(&wbk->usage);
 377                         _debug("USE WB KEY %u", key_serial(wbk->key));
 378                         break;
 379                 }
 380
 381                 wbk = NULL;
 382                 if (ret == -ENOKEY)
 383                         ret = ret2;
 384                 p = p->next;
 385         }
 386
 387         spin_unlock(&vnode->wb_lock);
 388         if (*_wbk)
 389                 afs_put_wb_key(*_wbk);
 390         *_wbk = wbk;
 391         return 0;
 392 }
 393
 394 static void afs_store_data_success(struct afs_operation *op)
 395 {
 396         struct afs_vnode *vnode = op->file[0].vnode;
 397
 398         op->ctime = op->file[0].scb.status.mtime_client;
 399         afs_vnode_commit_status(op, &op->file[0]);
 400         if (op->error == 0) {
 401                 if (!op->store.laundering)
 402                         afs_pages_written_back(vnode, op->store.first, op->store.last);
 403                 afs_stat_v(vnode, n_stores);
 404                 atomic_long_add((op->store.last * PAGE_SIZE + op->store.last_to) -
 405                                 (op->store.first * PAGE_SIZE + op->store.first_offset),
 406                                 &afs_v2net(vnode)->n_store_bytes);
 407         }
 408 }
 409
 410 static const struct afs_operation_ops afs_store_data_operation = {
 411         .issue_afs_rpc  = afs_fs_store_data,
 412         .issue_yfs_rpc  = yfs_fs_store_data,
 413         .success        = afs_store_data_success,
 414 };
 415
 416 /*
 417  * write to a file
 418  */
 419 static int afs_store_data(struct address_space *mapping,
 420                           pgoff_t first, pgoff_t last,
 421                           unsigned offset, unsigned to, bool laundering)
 422 {
 423         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 424         struct afs_operation *op;
 425         struct afs_wb_key *wbk = NULL;
 426         int ret;
 427
 428         _enter("%s{%llx:%llu.%u},%lx,%lx,%x,%x",
 429                vnode->volume->name,
 430                vnode->fid.vid,
 431                vnode->fid.vnode,
 432                vnode->fid.unique,
 433                first, last, offset, to);
 434
 435         ret = afs_get_writeback_key(vnode, &wbk);
 436         if (ret) {
 437                 _leave(" = %d [no keys]", ret);
 438                 return ret;
 439         }
 440
 441         op = afs_alloc_operation(wbk->key, vnode->volume);
 442         if (IS_ERR(op)) {
 443                 afs_put_wb_key(wbk);
 444                 return -ENOMEM;
 445         }
 446
 447         afs_op_set_vnode(op, 0, vnode);
 448         op->file[0].dv_delta = 1;
 449         op->store.mapping = mapping;
 450         op->store.first = first;
 451         op->store.last = last;
 452         op->store.first_offset = offset;
 453         op->store.last_to = to;
 454         op->store.laundering = laundering;
 455         op->mtime = vnode->vfs_inode.i_mtime;
 456         op->flags |= AFS_OPERATION_UNINTR;
 457         op->ops = &afs_store_data_operation;
 458
 459 try_next_key:
 460         afs_begin_vnode_operation(op);
 461         afs_wait_for_operation(op);
 462
 463         switch (op->error) {
 464         case -EACCES:
 465         case -EPERM:
 466         case -ENOKEY:
 467         case -EKEYEXPIRED:
 468         case -EKEYREJECTED:
 469         case -EKEYREVOKED:
 470                 _debug("next");
 471
 472                 ret = afs_get_writeback_key(vnode, &wbk);
 473                 if (ret == 0) {
 474                         key_put(op->key);
 475                         op->key = key_get(wbk->key);
 476                         goto try_next_key;
 477                 }
 478                 break;
 479         }
 480
 481         afs_put_wb_key(wbk);
 482         _leave(" = %d", op->error);
 483         return afs_put_operation(op);
 484 }
 485
 486 /*
 487  * Synchronously write back the locked page and any subsequent non-locked dirty
 488  * pages.
 489  */
 490 static int afs_write_back_from_locked_page(struct address_space *mapping,
 491                                            struct writeback_control *wbc,
 492                                            struct page *primary_page,
 493                                            pgoff_t final_page)
 494 {
 495         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 496         struct page *pages[8], *page;
 497         unsigned long count, priv;
 498         unsigned n, offset, to, f, t;
 499         pgoff_t start, first, last;
 500         loff_t i_size, end;
 501         int loop, ret;
 502
 503         _enter(",%lx", primary_page->index);
 504
 505         count = 1;
 506         if (test_set_page_writeback(primary_page))
 507                 BUG();
 508
 509         /* Find all consecutive lockable dirty pages that have contiguous
 510          * written regions, stopping when we find a page that is not
 511          * immediately lockable, is not dirty or is missing, or we reach the
 512          * end of the range.
 513          */
 514         start = primary_page->index;
 515         priv = page_private(primary_page);
 516         offset = afs_page_dirty_from(priv);
 517         to = afs_page_dirty_to(priv);
 518         trace_afs_page_dirty(vnode, tracepoint_string("store"),
 519                              primary_page->index, priv);
 520
 521         WARN_ON(offset == to);
 522         if (offset == to)
 523                 trace_afs_page_dirty(vnode, tracepoint_string("WARN"),
 524                                      primary_page->index, priv);
 525
 526         if (start >= final_page ||
 527             (to < PAGE_SIZE && !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)))
 528                 goto no_more;
 529
 530         start++;
 531         do {
 532                 _debug("more %lx [%lx]", start, count);
 533                 n = final_page - start + 1;
 534                 if (n > ARRAY_SIZE(pages))
 535                         n = ARRAY_SIZE(pages);
 536                 n = find_get_pages_contig(mapping, start, ARRAY_SIZE(pages), pages);
 537                 _debug("fgpc %u", n);
 538                 if (n == 0)
 539                         goto no_more;
 540                 if (pages[0]->index != start) {
 541                         do {
 542                                 put_page(pages[--n]);
 543                         } while (n > 0);
 544                         goto no_more;
 545                 }
 546
 547                 for (loop = 0; loop < n; loop++) {
 548                         page = pages[loop];
 549                         if (to != PAGE_SIZE &&
 550                             !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags))
 551                                 break;
 552                         if (page->index > final_page)
 553                                 break;
 554                         if (!trylock_page(page))
 555                                 break;
 556                         if (!PageDirty(page) || PageWriteback(page)) {
 557                                 unlock_page(page);
 558                                 break;
 559                         }
 560
 561                         priv = page_private(page);
 562                         f = afs_page_dirty_from(priv);
 563                         t = afs_page_dirty_to(priv);
 564                         if (f != 0 &&
 565                             !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)) {
 566                                 unlock_page(page);
 567                                 break;
 568                         }
 569                         to = t;
 570
 571                         trace_afs_page_dirty(vnode, tracepoint_string("store+"),
 572                                              page->index, priv);
 573
 574                         if (!clear_page_dirty_for_io(page))
 575                                 BUG();
 576                         if (test_set_page_writeback(page))
 577                                 BUG();
 578                         unlock_page(page);
 579                         put_page(page);
 580                 }
 581                 count += loop;
 582                 if (loop < n) {
 583                         for (; loop < n; loop++)
 584                                 put_page(pages[loop]);
 585                         goto no_more;
 586                 }
 587
 588                 start += loop;
 589         } while (start <= final_page && count < 65536);
 590
 591 no_more:
 592         /* We now have a contiguous set of dirty pages, each with writeback
 593          * set; the first page is still locked at this point, but all the rest
 594          * have been unlocked.
 595          */
 596         unlock_page(primary_page);
 597
 598         first = primary_page->index;
 599         last = first + count - 1;
 600
 601         end = (loff_t)last * PAGE_SIZE + to;
 602         i_size = i_size_read(&vnode->vfs_inode);
 603
 604         _debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
 605         if (end > i_size)
 606                 to = i_size & ~PAGE_MASK;
 607
 608         ret = afs_store_data(mapping, first, last, offset, to, false);
 609         switch (ret) {
 610         case 0:
 611                 ret = count;
 612                 break;
 613
 614         default:
 615                 pr_notice("kAFS: Unexpected error from FS.StoreData %d\n", ret);
 616                 fallthrough;
 617         case -EACCES:
 618         case -EPERM:
 619         case -ENOKEY:
 620         case -EKEYEXPIRED:
 621         case -EKEYREJECTED:
 622         case -EKEYREVOKED:
 623                 afs_redirty_pages(wbc, mapping, first, last);
 624                 mapping_set_error(mapping, ret);
 625                 break;
 626
 627         case -EDQUOT:
 628         case -ENOSPC:
 629                 afs_redirty_pages(wbc, mapping, first, last);
 630                 mapping_set_error(mapping, -ENOSPC);
 631                 break;
 632
 633         case -EROFS:
 634         case -EIO:
 635         case -EREMOTEIO:
 636         case -EFBIG:
 637         case -ENOENT:
 638         case -ENOMEDIUM:
 639         case -ENXIO:
 640                 trace_afs_file_error(vnode, ret, afs_file_error_writeback_fail);
 641                 afs_kill_pages(mapping, first, last);
 642                 mapping_set_error(mapping, ret);
 643                 break;
 644         }
 645
 646         _leave(" = %d", ret);
 647         return ret;
 648 }
 649
 650 /*
 651  * write a page back to the server
 652  * - the caller locked the page for us
 653  */
 654 int afs_writepage(struct page *page, struct writeback_control *wbc)
 655 {
 656         int ret;
 657
 658         _enter("{%lx},", page->index);
 659
 660         ret = afs_write_back_from_locked_page(page->mapping, wbc, page,
 661                                               wbc->range_end >> PAGE_SHIFT);
 662         if (ret < 0) {
 663                 _leave(" = %d", ret);
 664                 return 0;
 665         }
 666
 667         wbc->nr_to_write -= ret;
 668
 669         _leave(" = 0");
 670         return 0;
 671 }
 672
 673 /*
 674  * write a region of pages back to the server
 675  */
 676 static int afs_writepages_region(struct address_space *mapping,
 677                                  struct writeback_control *wbc,
 678                                  pgoff_t index, pgoff_t end, pgoff_t *_next)
 679 {
 680         struct page *page;
 681         int ret, n;
 682
 683         _enter(",,%lx,%lx,", index, end);
 684
 685         do {
 686                 n = find_get_pages_range_tag(mapping, &index, end,
 687                                         PAGECACHE_TAG_DIRTY, 1, &page);
 688                 if (!n)
 689                         break;
 690
 691                 _debug("wback %lx", page->index);
 692
 693                 /*
 694                  * at this point we hold neither the i_pages lock nor the
 695                  * page lock: the page may be truncated or invalidated
 696                  * (changing page->mapping to NULL), or even swizzled
 697                  * back from swapper_space to tmpfs file mapping
 698                  */
 699                 ret = lock_page_killable(page);
 700                 if (ret < 0) {
 701                         put_page(page);
 702                         _leave(" = %d", ret);
 703                         return ret;
 704                 }
 705
 706                 if (page->mapping != mapping || !PageDirty(page)) {
 707                         unlock_page(page);
 708                         put_page(page);
 709                         continue;
 710                 }
 711
 712                 if (PageWriteback(page)) {
 713                         unlock_page(page);
 714                         if (wbc->sync_mode != WB_SYNC_NONE)
 715                                 wait_on_page_writeback(page);
 716                         put_page(page);
 717                         continue;
 718                 }
 719
 720                 if (!clear_page_dirty_for_io(page))
 721                         BUG();
 722                 ret = afs_write_back_from_locked_page(mapping, wbc, page, end);
 723                 put_page(page);
 724                 if (ret < 0) {
 725                         _leave(" = %d", ret);
 726                         return ret;
 727                 }
 728
 729                 wbc->nr_to_write -= ret;
 730
 731                 cond_resched();
 732         } while (index < end && wbc->nr_to_write > 0);
 733
 734         *_next = index;
 735         _leave(" = 0 [%lx]", *_next);
 736         return 0;
 737 }
 738
 739 /*
 740  * write some of the pending data back to the server
 741  */
 742 int afs_writepages(struct address_space *mapping,
 743                    struct writeback_control *wbc)
 744 {
 745         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 746         pgoff_t start, end, next;
 747         int ret;
 748
 749         _enter("");
 750
 751         /* We have to be careful as we can end up racing with setattr()
 752          * truncating the pagecache since the caller doesn't take a lock here
 753          * to prevent it.
 754          */
 755         if (wbc->sync_mode == WB_SYNC_ALL)
 756                 down_read(&vnode->validate_lock);
 757         else if (!down_read_trylock(&vnode->validate_lock))
 758                 return 0;
 759
 760         if (wbc->range_cyclic) {
 761                 start = mapping->writeback_index;
 762                 end = -1;
 763                 ret = afs_writepages_region(mapping, wbc, start, end, &next);
 764                 if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
 765                         ret = afs_writepages_region(mapping, wbc, 0, start,
 766                                                     &next);
 767                 mapping->writeback_index = next;
 768         } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
 769                 end = (pgoff_t)(LLONG_MAX >> PAGE_SHIFT);
 770                 ret = afs_writepages_region(mapping, wbc, 0, end, &next);
 771                 if (wbc->nr_to_write > 0)
 772                         mapping->writeback_index = next;
 773         } else {
 774                 start = wbc->range_start >> PAGE_SHIFT;
 775                 end = wbc->range_end >> PAGE_SHIFT;
 776                 ret = afs_writepages_region(mapping, wbc, start, end, &next);
 777         }
 778
 779         up_read(&vnode->validate_lock);
 780         _leave(" = %d", ret);
 781         return ret;
 782 }
 783
 784 /*
 785  * write to an AFS file
 786  */
 787 ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
 788 {
 789         struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
 790         ssize_t result;
 791         size_t count = iov_iter_count(from);
 792
 793         _enter("{%llx:%llu},{%zu},",
 794                vnode->fid.vid, vnode->fid.vnode, count);
 795
 796         if (IS_SWAPFILE(&vnode->vfs_inode)) {
 797                 printk(KERN_INFO
 798                        "AFS: Attempt to write to active swap file!\n");
 799                 return -EBUSY;
 800         }
 801
 802         if (!count)
 803                 return 0;
 804
 805         result = generic_file_write_iter(iocb, from);
 806
 807         _leave(" = %zd", result);
 808         return result;
 809 }
 810
 811 /*
 812  * flush any dirty pages for this process, and check for write errors.
 813  * - the return status from this call provides a reliable indication of
 814  *   whether any write errors occurred for this process.
 815  */
 816 int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 817 {
 818         struct inode *inode = file_inode(file);
 819         struct afs_vnode *vnode = AFS_FS_I(inode);
 820
 821         _enter("{%llx:%llu},{n=%pD},%d",
 822                vnode->fid.vid, vnode->fid.vnode, file,
 823                datasync);
 824
 825         return file_write_and_wait_range(file, start, end);
 826 }
 827
 828 /*
 829  * notification that a previously read-only page is about to become writable
 830  * - if it returns an error, the caller will deliver a bus error signal
 831  */
 832 vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
 833 {
 834         struct file *file = vmf->vma->vm_file;
 835         struct inode *inode = file_inode(file);
 836         struct afs_vnode *vnode = AFS_FS_I(inode);
 837         unsigned long priv;
 838
 839         _enter("{{%llx:%llu}},{%lx}",
 840                vnode->fid.vid, vnode->fid.vnode, vmf->page->index);
 841
 842         sb_start_pagefault(inode->i_sb);
 843
 844         /* Wait for the page to be written to the cache before we allow it to
 845          * be modified.  We then assume the entire page will need writing back.
 846          */
 847 #ifdef CONFIG_AFS_FSCACHE
 848         fscache_wait_on_page_write(vnode->cache, vmf->page);
 849 #endif
 850
 851         if (PageWriteback(vmf->page) &&
 852             wait_on_page_bit_killable(vmf->page, PG_writeback) < 0)
 853                 return VM_FAULT_RETRY;
 854
 855         if (lock_page_killable(vmf->page) < 0)
 856                 return VM_FAULT_RETRY;
 857
 858         /* We mustn't change page->private until writeback is complete as that
 859          * details the portion of the page we need to write back and we might
 860          * need to redirty the page if there's a problem.
 861          */
 862         wait_on_page_writeback(vmf->page);
 863
 864         priv = afs_page_dirty(0, PAGE_SIZE);
 865         priv = afs_page_dirty_mmapped(priv);
 866         trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"),
 867                              vmf->page->index, priv);
 868         if (PagePrivate(vmf->page))
 869                 set_page_private(vmf->page, priv);
 870         else
 871                 attach_page_private(vmf->page, (void *)priv);
 872         file_update_time(file);
 873
 874         sb_end_pagefault(inode->i_sb);
 875         return VM_FAULT_LOCKED;
 876 }
 877
 878 /*
 879  * Prune the keys cached for writeback.  The caller must hold vnode->wb_lock.
 880  */
 881 void afs_prune_wb_keys(struct afs_vnode *vnode)
 882 {
 883         LIST_HEAD(graveyard);
 884         struct afs_wb_key *wbk, *tmp;
 885
 886         /* Discard unused keys */
 887         spin_lock(&vnode->wb_lock);
 888
 889         if (!mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
 890             !mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_DIRTY)) {
 891                 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
 892                         if (refcount_read(&wbk->usage) == 1)
 893                                 list_move(&wbk->vnode_link, &graveyard);
 894                 }
 895         }
 896
 897         spin_unlock(&vnode->wb_lock);
 898
 899         while (!list_empty(&graveyard)) {
 900                 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
 901                 list_del(&wbk->vnode_link);
 902                 afs_put_wb_key(wbk);
 903         }
 904 }
 905
 906 /*
 907  * Clean up a page during invalidation.
 908  */
 909 int afs_launder_page(struct page *page)
 910 {
 911         struct address_space *mapping = page->mapping;
 912         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 913         unsigned long priv;
 914         unsigned int f, t;
 915         int ret = 0;
 916
 917         _enter("{%lx}", page->index);
 918
 919         priv = page_private(page);
 920         if (clear_page_dirty_for_io(page)) {
 921                 f = 0;
 922                 t = PAGE_SIZE;
 923                 if (PagePrivate(page)) {
 924                         f = afs_page_dirty_from(priv);
 925                         t = afs_page_dirty_to(priv);
 926                 }
 927
 928                 trace_afs_page_dirty(vnode, tracepoint_string("launder"),
 929                                      page->index, priv);
 930                 ret = afs_store_data(mapping, page->index, page->index, t, f, true);
 931         }
 932
 933         priv = (unsigned long)detach_page_private(page);
 934         trace_afs_page_dirty(vnode, tracepoint_string("laundered"),
 935                              page->index, priv);
 936
 937 #ifdef CONFIG_AFS_FSCACHE
 938         if (PageFsCache(page)) {
 939                 fscache_wait_on_page_write(vnode->cache, page);
 940                 fscache_uncache_page(vnode->cache, page);
 941         }
 942 #endif
 943         return ret;
 944 }