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 <linux/netfs.h>
  15 #include "internal.h"
  16
  17 static int afs_writepages_region(struct address_space *mapping,
  18                                  struct writeback_control *wbc,
  19                                  loff_t start, loff_t end, loff_t *_next,
  20                                  bool max_one_loop);
  21
  22 static void afs_write_to_cache(struct afs_vnode *vnode, loff_t start, size_t len,
  23                                loff_t i_size, bool caching);
  24
  25 #ifdef CONFIG_AFS_FSCACHE
  26 /*
  27  * Mark a page as having been made dirty and thus needing writeback.  We also
  28  * need to pin the cache object to write back to.
  29  */
  30 bool afs_dirty_folio(struct address_space *mapping, struct folio *folio)
  31 {
  32         return fscache_dirty_folio(mapping, folio,
  33                                 afs_vnode_cache(AFS_FS_I(mapping->host)));
  34 }
  35 static void afs_folio_start_fscache(bool caching, struct folio *folio)
  36 {
  37         if (caching)
  38                 folio_start_fscache(folio);
  39 }
  40 #else
  41 static void afs_folio_start_fscache(bool caching, struct folio *folio)
  42 {
  43 }
  44 #endif
  45
  46 /*
  47  * Flush out a conflicting write.  This may extend the write to the surrounding
  48  * pages if also dirty and contiguous to the conflicting region..
  49  */
  50 static int afs_flush_conflicting_write(struct address_space *mapping,
  51                                        struct folio *folio)
  52 {
  53         struct writeback_control wbc = {
  54                 .sync_mode      = WB_SYNC_ALL,
  55                 .nr_to_write    = LONG_MAX,
  56                 .range_start    = folio_pos(folio),
  57                 .range_end      = LLONG_MAX,
  58         };
  59         loff_t next;
  60
  61         return afs_writepages_region(mapping, &wbc, folio_pos(folio), LLONG_MAX,
  62                                      &next, true);
  63 }
  64
  65 /*
  66  * prepare to perform part of a write to a page
  67  */
  68 int afs_write_begin(struct file *file, struct address_space *mapping,
  69                     loff_t pos, unsigned len,
  70                     struct page **_page, void **fsdata)
  71 {
  72         struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
  73         struct folio *folio;
  74         unsigned long priv;
  75         unsigned f, from;
  76         unsigned t, to;
  77         pgoff_t index;
  78         int ret;
  79
  80         _enter("{%llx:%llu},%llx,%x",
  81                vnode->fid.vid, vnode->fid.vnode, pos, len);
  82
  83         /* Prefetch area to be written into the cache if we're caching this
  84          * file.  We need to do this before we get a lock on the page in case
  85          * there's more than one writer competing for the same cache block.
  86          */
  87         ret = netfs_write_begin(&vnode->netfs, file, mapping, pos, len, &folio, fsdata);
  88         if (ret < 0)
  89                 return ret;
  90
  91         index = folio_index(folio);
  92         from = pos - index * PAGE_SIZE;
  93         to = from + len;
  94
  95 try_again:
  96         /* See if this page is already partially written in a way that we can
  97          * merge the new write with.
  98          */
  99         if (folio_test_private(folio)) {
 100                 priv = (unsigned long)folio_get_private(folio);
 101                 f = afs_folio_dirty_from(folio, priv);
 102                 t = afs_folio_dirty_to(folio, priv);
 103                 ASSERTCMP(f, <=, t);
 104
 105                 if (folio_test_writeback(folio)) {
 106                         trace_afs_folio_dirty(vnode, tracepoint_string("alrdy"), folio);
 107                         folio_unlock(folio);
 108                         goto wait_for_writeback;
 109                 }
 110                 /* If the file is being filled locally, allow inter-write
 111                  * spaces to be merged into writes.  If it's not, only write
 112                  * back what the user gives us.
 113                  */
 114                 if (!test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags) &&
 115                     (to < f || from > t))
 116                         goto flush_conflicting_write;
 117         }
 118
 119         *_page = folio_file_page(folio, pos / PAGE_SIZE);
 120         _leave(" = 0");
 121         return 0;
 122
 123         /* The previous write and this write aren't adjacent or overlapping, so
 124          * flush the page out.
 125          */
 126 flush_conflicting_write:
 127         trace_afs_folio_dirty(vnode, tracepoint_string("confl"), folio);
 128         folio_unlock(folio);
 129
 130         ret = afs_flush_conflicting_write(mapping, folio);
 131         if (ret < 0)
 132                 goto error;
 133
 134 wait_for_writeback:
 135         ret = folio_wait_writeback_killable(folio);
 136         if (ret < 0)
 137                 goto error;
 138
 139         ret = folio_lock_killable(folio);
 140         if (ret < 0)
 141                 goto error;
 142         goto try_again;
 143
 144 error:
 145         folio_put(folio);
 146         _leave(" = %d", ret);
 147         return ret;
 148 }
 149
 150 /*
 151  * finalise part of a write to a page
 152  */
 153 int afs_write_end(struct file *file, struct address_space *mapping,
 154                   loff_t pos, unsigned len, unsigned copied,
 155                   struct page *subpage, void *fsdata)
 156 {
 157         struct folio *folio = page_folio(subpage);
 158         struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
 159         unsigned long priv;
 160         unsigned int f, from = offset_in_folio(folio, pos);
 161         unsigned int t, to = from + copied;
 162         loff_t i_size, write_end_pos;
 163
 164         _enter("{%llx:%llu},{%lx}",
 165                vnode->fid.vid, vnode->fid.vnode, folio_index(folio));
 166
 167         if (!folio_test_uptodate(folio)) {
 168                 if (copied < len) {
 169                         copied = 0;
 170                         goto out;
 171                 }
 172
 173                 folio_mark_uptodate(folio);
 174         }
 175
 176         if (copied == 0)
 177                 goto out;
 178
 179         write_end_pos = pos + copied;
 180
 181         i_size = i_size_read(&vnode->netfs.inode);
 182         if (write_end_pos > i_size) {
 183                 write_seqlock(&vnode->cb_lock);
 184                 i_size = i_size_read(&vnode->netfs.inode);
 185                 if (write_end_pos > i_size)
 186                         afs_set_i_size(vnode, write_end_pos);
 187                 write_sequnlock(&vnode->cb_lock);
 188                 fscache_update_cookie(afs_vnode_cache(vnode), NULL, &write_end_pos);
 189         }
 190
 191         if (folio_test_private(folio)) {
 192                 priv = (unsigned long)folio_get_private(folio);
 193                 f = afs_folio_dirty_from(folio, priv);
 194                 t = afs_folio_dirty_to(folio, priv);
 195                 if (from < f)
 196                         f = from;
 197                 if (to > t)
 198                         t = to;
 199                 priv = afs_folio_dirty(folio, f, t);
 200                 folio_change_private(folio, (void *)priv);
 201                 trace_afs_folio_dirty(vnode, tracepoint_string("dirty+"), folio);
 202         } else {
 203                 priv = afs_folio_dirty(folio, from, to);
 204                 folio_attach_private(folio, (void *)priv);
 205                 trace_afs_folio_dirty(vnode, tracepoint_string("dirty"), folio);
 206         }
 207
 208         if (folio_mark_dirty(folio))
 209                 _debug("dirtied %lx", folio_index(folio));
 210
 211 out:
 212         folio_unlock(folio);
 213         folio_put(folio);
 214         return copied;
 215 }
 216
 217 /*
 218  * kill all the pages in the given range
 219  */
 220 static void afs_kill_pages(struct address_space *mapping,
 221                            loff_t start, loff_t len)
 222 {
 223         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 224         struct folio *folio;
 225         pgoff_t index = start / PAGE_SIZE;
 226         pgoff_t last = (start + len - 1) / PAGE_SIZE, next;
 227
 228         _enter("{%llx:%llu},%llx @%llx",
 229                vnode->fid.vid, vnode->fid.vnode, len, start);
 230
 231         do {
 232                 _debug("kill %lx (to %lx)", index, last);
 233
 234                 folio = filemap_get_folio(mapping, index);
 235                 if (IS_ERR(folio)) {
 236                         next = index + 1;
 237                         continue;
 238                 }
 239
 240                 next = folio_next_index(folio);
 241
 242                 folio_clear_uptodate(folio);
 243                 folio_end_writeback(folio);
 244                 folio_lock(folio);
 245                 generic_error_remove_page(mapping, &folio->page);
 246                 folio_unlock(folio);
 247                 folio_put(folio);
 248
 249         } while (index = next, index <= last);
 250
 251         _leave("");
 252 }
 253
 254 /*
 255  * Redirty all the pages in a given range.
 256  */
 257 static void afs_redirty_pages(struct writeback_control *wbc,
 258                               struct address_space *mapping,
 259                               loff_t start, loff_t len)
 260 {
 261         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 262         struct folio *folio;
 263         pgoff_t index = start / PAGE_SIZE;
 264         pgoff_t last = (start + len - 1) / PAGE_SIZE, next;
 265
 266         _enter("{%llx:%llu},%llx @%llx",
 267                vnode->fid.vid, vnode->fid.vnode, len, start);
 268
 269         do {
 270                 _debug("redirty %llx @%llx", len, start);
 271
 272                 folio = filemap_get_folio(mapping, index);
 273                 if (IS_ERR(folio)) {
 274                         next = index + 1;
 275                         continue;
 276                 }
 277
 278                 next = index + folio_nr_pages(folio);
 279                 folio_redirty_for_writepage(wbc, folio);
 280                 folio_end_writeback(folio);
 281                 folio_put(folio);
 282         } while (index = next, index <= last);
 283
 284         _leave("");
 285 }
 286
 287 /*
 288  * completion of write to server
 289  */
 290 static void afs_pages_written_back(struct afs_vnode *vnode, loff_t start, unsigned int len)
 291 {
 292         struct address_space *mapping = vnode->netfs.inode.i_mapping;
 293         struct folio *folio;
 294         pgoff_t end;
 295
 296         XA_STATE(xas, &mapping->i_pages, start / PAGE_SIZE);
 297
 298         _enter("{%llx:%llu},{%x @%llx}",
 299                vnode->fid.vid, vnode->fid.vnode, len, start);
 300
 301         rcu_read_lock();
 302
 303         end = (start + len - 1) / PAGE_SIZE;
 304         xas_for_each(&xas, folio, end) {
 305                 if (!folio_test_writeback(folio)) {
 306                         kdebug("bad %x @%llx page %lx %lx",
 307                                len, start, folio_index(folio), end);
 308                         ASSERT(folio_test_writeback(folio));
 309                 }
 310
 311                 trace_afs_folio_dirty(vnode, tracepoint_string("clear"), folio);
 312                 folio_detach_private(folio);
 313                 folio_end_writeback(folio);
 314         }
 315
 316         rcu_read_unlock();
 317
 318         afs_prune_wb_keys(vnode);
 319         _leave("");
 320 }
 321
 322 /*
 323  * Find a key to use for the writeback.  We cached the keys used to author the
 324  * writes on the vnode.  *_wbk will contain the last writeback key used or NULL
 325  * and we need to start from there if it's set.
 326  */
 327 static int afs_get_writeback_key(struct afs_vnode *vnode,
 328                                  struct afs_wb_key **_wbk)
 329 {
 330         struct afs_wb_key *wbk = NULL;
 331         struct list_head *p;
 332         int ret = -ENOKEY, ret2;
 333
 334         spin_lock(&vnode->wb_lock);
 335         if (*_wbk)
 336                 p = (*_wbk)->vnode_link.next;
 337         else
 338                 p = vnode->wb_keys.next;
 339
 340         while (p != &vnode->wb_keys) {
 341                 wbk = list_entry(p, struct afs_wb_key, vnode_link);
 342                 _debug("wbk %u", key_serial(wbk->key));
 343                 ret2 = key_validate(wbk->key);
 344                 if (ret2 == 0) {
 345                         refcount_inc(&wbk->usage);
 346                         _debug("USE WB KEY %u", key_serial(wbk->key));
 347                         break;
 348                 }
 349
 350                 wbk = NULL;
 351                 if (ret == -ENOKEY)
 352                         ret = ret2;
 353                 p = p->next;
 354         }
 355
 356         spin_unlock(&vnode->wb_lock);
 357         if (*_wbk)
 358                 afs_put_wb_key(*_wbk);
 359         *_wbk = wbk;
 360         return 0;
 361 }
 362
 363 static void afs_store_data_success(struct afs_operation *op)
 364 {
 365         struct afs_vnode *vnode = op->file[0].vnode;
 366
 367         op->ctime = op->file[0].scb.status.mtime_client;
 368         afs_vnode_commit_status(op, &op->file[0]);
 369         if (op->error == 0) {
 370                 if (!op->store.laundering)
 371                         afs_pages_written_back(vnode, op->store.pos, op->store.size);
 372                 afs_stat_v(vnode, n_stores);
 373                 atomic_long_add(op->store.size, &afs_v2net(vnode)->n_store_bytes);
 374         }
 375 }
 376
 377 static const struct afs_operation_ops afs_store_data_operation = {
 378         .issue_afs_rpc  = afs_fs_store_data,
 379         .issue_yfs_rpc  = yfs_fs_store_data,
 380         .success        = afs_store_data_success,
 381 };
 382
 383 /*
 384  * write to a file
 385  */
 386 static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter, loff_t pos,
 387                           bool laundering)
 388 {
 389         struct afs_operation *op;
 390         struct afs_wb_key *wbk = NULL;
 391         loff_t size = iov_iter_count(iter);
 392         int ret = -ENOKEY;
 393
 394         _enter("%s{%llx:%llu.%u},%llx,%llx",
 395                vnode->volume->name,
 396                vnode->fid.vid,
 397                vnode->fid.vnode,
 398                vnode->fid.unique,
 399                size, pos);
 400
 401         ret = afs_get_writeback_key(vnode, &wbk);
 402         if (ret) {
 403                 _leave(" = %d [no keys]", ret);
 404                 return ret;
 405         }
 406
 407         op = afs_alloc_operation(wbk->key, vnode->volume);
 408         if (IS_ERR(op)) {
 409                 afs_put_wb_key(wbk);
 410                 return -ENOMEM;
 411         }
 412
 413         afs_op_set_vnode(op, 0, vnode);
 414         op->file[0].dv_delta = 1;
 415         op->file[0].modification = true;
 416         op->store.pos = pos;
 417         op->store.size = size;
 418         op->store.laundering = laundering;
 419         op->flags |= AFS_OPERATION_UNINTR;
 420         op->ops = &afs_store_data_operation;
 421
 422 try_next_key:
 423         afs_begin_vnode_operation(op);
 424
 425         op->store.write_iter = iter;
 426         op->store.i_size = max(pos + size, vnode->netfs.remote_i_size);
 427         op->mtime = vnode->netfs.inode.i_mtime;
 428
 429         afs_wait_for_operation(op);
 430
 431         switch (op->error) {
 432         case -EACCES:
 433         case -EPERM:
 434         case -ENOKEY:
 435         case -EKEYEXPIRED:
 436         case -EKEYREJECTED:
 437         case -EKEYREVOKED:
 438                 _debug("next");
 439
 440                 ret = afs_get_writeback_key(vnode, &wbk);
 441                 if (ret == 0) {
 442                         key_put(op->key);
 443                         op->key = key_get(wbk->key);
 444                         goto try_next_key;
 445                 }
 446                 break;
 447         }
 448
 449         afs_put_wb_key(wbk);
 450         _leave(" = %d", op->error);
 451         return afs_put_operation(op);
 452 }
 453
 454 /*
 455  * Extend the region to be written back to include subsequent contiguously
 456  * dirty pages if possible, but don't sleep while doing so.
 457  *
 458  * If this page holds new content, then we can include filler zeros in the
 459  * writeback.
 460  */
 461 static void afs_extend_writeback(struct address_space *mapping,
 462                                  struct afs_vnode *vnode,
 463                                  long *_count,
 464                                  loff_t start,
 465                                  loff_t max_len,
 466                                  bool new_content,
 467                                  bool caching,
 468                                  unsigned int *_len)
 469 {
 470         struct folio_batch fbatch;
 471         struct folio *folio;
 472         unsigned long priv;
 473         unsigned int psize, filler = 0;
 474         unsigned int f, t;
 475         loff_t len = *_len;
 476         pgoff_t index = (start + len) / PAGE_SIZE;
 477         bool stop = true;
 478         unsigned int i;
 479
 480         XA_STATE(xas, &mapping->i_pages, index);
 481         folio_batch_init(&fbatch);
 482
 483         do {
 484                 /* Firstly, we gather up a batch of contiguous dirty pages
 485                  * under the RCU read lock - but we can't clear the dirty flags
 486                  * there if any of those pages are mapped.
 487                  */
 488                 rcu_read_lock();
 489
 490                 xas_for_each(&xas, folio, ULONG_MAX) {
 491                         stop = true;
 492                         if (xas_retry(&xas, folio))
 493                                 continue;
 494                         if (xa_is_value(folio))
 495                                 break;
 496                         if (folio_index(folio) != index)
 497                                 break;
 498
 499                         if (!folio_try_get_rcu(folio)) {
 500                                 xas_reset(&xas);
 501                                 continue;
 502                         }
 503
 504                         /* Has the page moved or been split? */
 505                         if (unlikely(folio != xas_reload(&xas))) {
 506                                 folio_put(folio);
 507                                 break;
 508                         }
 509
 510                         if (!folio_trylock(folio)) {
 511                                 folio_put(folio);
 512                                 break;
 513                         }
 514                         if (!folio_test_dirty(folio) ||
 515                             folio_test_writeback(folio) ||
 516                             folio_test_fscache(folio)) {
 517                                 folio_unlock(folio);
 518                                 folio_put(folio);
 519                                 break;
 520                         }
 521
 522                         psize = folio_size(folio);
 523                         priv = (unsigned long)folio_get_private(folio);
 524                         f = afs_folio_dirty_from(folio, priv);
 525                         t = afs_folio_dirty_to(folio, priv);
 526                         if (f != 0 && !new_content) {
 527                                 folio_unlock(folio);
 528                                 folio_put(folio);
 529                                 break;
 530                         }
 531
 532                         len += filler + t;
 533                         filler = psize - t;
 534                         if (len >= max_len || *_count <= 0)
 535                                 stop = true;
 536                         else if (t == psize || new_content)
 537                                 stop = false;
 538
 539                         index += folio_nr_pages(folio);
 540                         if (!folio_batch_add(&fbatch, folio))
 541                                 break;
 542                         if (stop)
 543                                 break;
 544                 }
 545
 546                 if (!stop)
 547                         xas_pause(&xas);
 548                 rcu_read_unlock();
 549
 550                 /* Now, if we obtained any folios, we can shift them to being
 551                  * writable and mark them for caching.
 552                  */
 553                 if (!folio_batch_count(&fbatch))
 554                         break;
 555
 556                 for (i = 0; i < folio_batch_count(&fbatch); i++) {
 557                         folio = fbatch.folios[i];
 558                         trace_afs_folio_dirty(vnode, tracepoint_string("store+"), folio);
 559
 560                         if (!folio_clear_dirty_for_io(folio))
 561                                 BUG();
 562                         if (folio_start_writeback(folio))
 563                                 BUG();
 564                         afs_folio_start_fscache(caching, folio);
 565
 566                         *_count -= folio_nr_pages(folio);
 567                         folio_unlock(folio);
 568                 }
 569
 570                 folio_batch_release(&fbatch);
 571                 cond_resched();
 572         } while (!stop);
 573
 574         *_len = len;
 575 }
 576
 577 /*
 578  * Synchronously write back the locked page and any subsequent non-locked dirty
 579  * pages.
 580  */
 581 static ssize_t afs_write_back_from_locked_folio(struct address_space *mapping,
 582                                                 struct writeback_control *wbc,
 583                                                 struct folio *folio,
 584                                                 loff_t start, loff_t end)
 585 {
 586         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 587         struct iov_iter iter;
 588         unsigned long priv;
 589         unsigned int offset, to, len, max_len;
 590         loff_t i_size = i_size_read(&vnode->netfs.inode);
 591         bool new_content = test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
 592         bool caching = fscache_cookie_enabled(afs_vnode_cache(vnode));
 593         long count = wbc->nr_to_write;
 594         int ret;
 595
 596         _enter(",%lx,%llx-%llx", folio_index(folio), start, end);
 597
 598         if (folio_start_writeback(folio))
 599                 BUG();
 600         afs_folio_start_fscache(caching, folio);
 601
 602         count -= folio_nr_pages(folio);
 603
 604         /* Find all consecutive lockable dirty pages that have contiguous
 605          * written regions, stopping when we find a page that is not
 606          * immediately lockable, is not dirty or is missing, or we reach the
 607          * end of the range.
 608          */
 609         priv = (unsigned long)folio_get_private(folio);
 610         offset = afs_folio_dirty_from(folio, priv);
 611         to = afs_folio_dirty_to(folio, priv);
 612         trace_afs_folio_dirty(vnode, tracepoint_string("store"), folio);
 613
 614         len = to - offset;
 615         start += offset;
 616         if (start < i_size) {
 617                 /* Trim the write to the EOF; the extra data is ignored.  Also
 618                  * put an upper limit on the size of a single storedata op.
 619                  */
 620                 max_len = 65536 * 4096;
 621                 max_len = min_t(unsigned long long, max_len, end - start + 1);
 622                 max_len = min_t(unsigned long long, max_len, i_size - start);
 623
 624                 if (len < max_len &&
 625                     (to == folio_size(folio) || new_content))
 626                         afs_extend_writeback(mapping, vnode, &count,
 627                                              start, max_len, new_content,
 628                                              caching, &len);
 629                 len = min_t(loff_t, len, max_len);
 630         }
 631
 632         /* We now have a contiguous set of dirty pages, each with writeback
 633          * set; the first page is still locked at this point, but all the rest
 634          * have been unlocked.
 635          */
 636         folio_unlock(folio);
 637
 638         if (start < i_size) {
 639                 _debug("write back %x @%llx [%llx]", len, start, i_size);
 640
 641                 /* Speculatively write to the cache.  We have to fix this up
 642                  * later if the store fails.
 643                  */
 644                 afs_write_to_cache(vnode, start, len, i_size, caching);
 645
 646                 iov_iter_xarray(&iter, ITER_SOURCE, &mapping->i_pages, start, len);
 647                 ret = afs_store_data(vnode, &iter, start, false);
 648         } else {
 649                 _debug("write discard %x @%llx [%llx]", len, start, i_size);
 650
 651                 /* The dirty region was entirely beyond the EOF. */
 652                 fscache_clear_page_bits(mapping, start, len, caching);
 653                 afs_pages_written_back(vnode, start, len);
 654                 ret = 0;
 655         }
 656
 657         switch (ret) {
 658         case 0:
 659                 wbc->nr_to_write = count;
 660                 ret = len;
 661                 break;
 662
 663         default:
 664                 pr_notice("kAFS: Unexpected error from FS.StoreData %d\n", ret);
 665                 fallthrough;
 666         case -EACCES:
 667         case -EPERM:
 668         case -ENOKEY:
 669         case -EKEYEXPIRED:
 670         case -EKEYREJECTED:
 671         case -EKEYREVOKED:
 672         case -ENETRESET:
 673                 afs_redirty_pages(wbc, mapping, start, len);
 674                 mapping_set_error(mapping, ret);
 675                 break;
 676
 677         case -EDQUOT:
 678         case -ENOSPC:
 679                 afs_redirty_pages(wbc, mapping, start, len);
 680                 mapping_set_error(mapping, -ENOSPC);
 681                 break;
 682
 683         case -EROFS:
 684         case -EIO:
 685         case -EREMOTEIO:
 686         case -EFBIG:
 687         case -ENOENT:
 688         case -ENOMEDIUM:
 689         case -ENXIO:
 690                 trace_afs_file_error(vnode, ret, afs_file_error_writeback_fail);
 691                 afs_kill_pages(mapping, start, len);
 692                 mapping_set_error(mapping, ret);
 693                 break;
 694         }
 695
 696         _leave(" = %d", ret);
 697         return ret;
 698 }
 699
 700 /*
 701  * write a region of pages back to the server
 702  */
 703 static int afs_writepages_region(struct address_space *mapping,
 704                                  struct writeback_control *wbc,
 705                                  loff_t start, loff_t end, loff_t *_next,
 706                                  bool max_one_loop)
 707 {
 708         struct folio *folio;
 709         struct folio_batch fbatch;
 710         ssize_t ret;
 711         unsigned int i;
 712         int n, skips = 0;
 713
 714         _enter("%llx,%llx,", start, end);
 715         folio_batch_init(&fbatch);
 716
 717         do {
 718                 pgoff_t index = start / PAGE_SIZE;
 719
 720                 n = filemap_get_folios_tag(mapping, &index, end / PAGE_SIZE,
 721                                         PAGECACHE_TAG_DIRTY, &fbatch);
 722
 723                 if (!n)
 724                         break;
 725                 for (i = 0; i < n; i++) {
 726                         folio = fbatch.folios[i];
 727                         start = folio_pos(folio); /* May regress with THPs */
 728
 729                         _debug("wback %lx", folio_index(folio));
 730
 731                         /* At this point we hold neither the i_pages lock nor the
 732                          * page lock: the page may be truncated or invalidated
 733                          * (changing page->mapping to NULL), or even swizzled
 734                          * back from swapper_space to tmpfs file mapping
 735                          */
 736 try_again:
 737                         if (wbc->sync_mode != WB_SYNC_NONE) {
 738                                 ret = folio_lock_killable(folio);
 739                                 if (ret < 0) {
 740                                         folio_batch_release(&fbatch);
 741                                         return ret;
 742                                 }
 743                         } else {
 744                                 if (!folio_trylock(folio))
 745                                         continue;
 746                         }
 747
 748                         if (folio->mapping != mapping ||
 749                             !folio_test_dirty(folio)) {
 750                                 start += folio_size(folio);
 751                                 folio_unlock(folio);
 752                                 continue;
 753                         }
 754
 755                         if (folio_test_writeback(folio) ||
 756                             folio_test_fscache(folio)) {
 757                                 folio_unlock(folio);
 758                                 if (wbc->sync_mode != WB_SYNC_NONE) {
 759                                         folio_wait_writeback(folio);
 760 #ifdef CONFIG_AFS_FSCACHE
 761                                         folio_wait_fscache(folio);
 762 #endif
 763                                         goto try_again;
 764                                 }
 765
 766                                 start += folio_size(folio);
 767                                 if (wbc->sync_mode == WB_SYNC_NONE) {
 768                                         if (skips >= 5 || need_resched()) {
 769                                                 *_next = start;
 770                                                 folio_batch_release(&fbatch);
 771                                                 _leave(" = 0 [%llx]", *_next);
 772                                                 return 0;
 773                                         }
 774                                         skips++;
 775                                 }
 776                                 continue;
 777                         }
 778
 779                         if (!folio_clear_dirty_for_io(folio))
 780                                 BUG();
 781                         ret = afs_write_back_from_locked_folio(mapping, wbc,
 782                                         folio, start, end);
 783                         if (ret < 0) {
 784                                 _leave(" = %zd", ret);
 785                                 folio_batch_release(&fbatch);
 786                                 return ret;
 787                         }
 788
 789                         start += ret;
 790                 }
 791
 792                 folio_batch_release(&fbatch);
 793                 cond_resched();
 794         } while (wbc->nr_to_write > 0);
 795
 796         *_next = start;
 797         _leave(" = 0 [%llx]", *_next);
 798         return 0;
 799 }
 800
 801 /*
 802  * write some of the pending data back to the server
 803  */
 804 int afs_writepages(struct address_space *mapping,
 805                    struct writeback_control *wbc)
 806 {
 807         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 808         loff_t start, next;
 809         int ret;
 810
 811         _enter("");
 812
 813         /* We have to be careful as we can end up racing with setattr()
 814          * truncating the pagecache since the caller doesn't take a lock here
 815          * to prevent it.
 816          */
 817         if (wbc->sync_mode == WB_SYNC_ALL)
 818                 down_read(&vnode->validate_lock);
 819         else if (!down_read_trylock(&vnode->validate_lock))
 820                 return 0;
 821
 822         if (wbc->range_cyclic) {
 823                 start = mapping->writeback_index * PAGE_SIZE;
 824                 ret = afs_writepages_region(mapping, wbc, start, LLONG_MAX,
 825                                             &next, false);
 826                 if (ret == 0) {
 827                         mapping->writeback_index = next / PAGE_SIZE;
 828                         if (start > 0 && wbc->nr_to_write > 0) {
 829                                 ret = afs_writepages_region(mapping, wbc, 0,
 830                                                             start, &next, false);
 831                                 if (ret == 0)
 832                                         mapping->writeback_index =
 833                                                 next / PAGE_SIZE;
 834                         }
 835                 }
 836         } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
 837                 ret = afs_writepages_region(mapping, wbc, 0, LLONG_MAX,
 838                                             &next, false);
 839                 if (wbc->nr_to_write > 0 && ret == 0)
 840                         mapping->writeback_index = next / PAGE_SIZE;
 841         } else {
 842                 ret = afs_writepages_region(mapping, wbc,
 843                                             wbc->range_start, wbc->range_end,
 844                                             &next, false);
 845         }
 846
 847         up_read(&vnode->validate_lock);
 848         _leave(" = %d", ret);
 849         return ret;
 850 }
 851
 852 /*
 853  * write to an AFS file
 854  */
 855 ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
 856 {
 857         struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
 858         struct afs_file *af = iocb->ki_filp->private_data;
 859         ssize_t result;
 860         size_t count = iov_iter_count(from);
 861
 862         _enter("{%llx:%llu},{%zu},",
 863                vnode->fid.vid, vnode->fid.vnode, count);
 864
 865         if (IS_SWAPFILE(&vnode->netfs.inode)) {
 866                 printk(KERN_INFO
 867                        "AFS: Attempt to write to active swap file!\n");
 868                 return -EBUSY;
 869         }
 870
 871         if (!count)
 872                 return 0;
 873
 874         result = afs_validate(vnode, af->key);
 875         if (result < 0)
 876                 return result;
 877
 878         result = generic_file_write_iter(iocb, from);
 879
 880         _leave(" = %zd", result);
 881         return result;
 882 }
 883
 884 /*
 885  * flush any dirty pages for this process, and check for write errors.
 886  * - the return status from this call provides a reliable indication of
 887  *   whether any write errors occurred for this process.
 888  */
 889 int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 890 {
 891         struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
 892         struct afs_file *af = file->private_data;
 893         int ret;
 894
 895         _enter("{%llx:%llu},{n=%pD},%d",
 896                vnode->fid.vid, vnode->fid.vnode, file,
 897                datasync);
 898
 899         ret = afs_validate(vnode, af->key);
 900         if (ret < 0)
 901                 return ret;
 902
 903         return file_write_and_wait_range(file, start, end);
 904 }
 905
 906 /*
 907  * notification that a previously read-only page is about to become writable
 908  * - if it returns an error, the caller will deliver a bus error signal
 909  */
 910 vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
 911 {
 912         struct folio *folio = page_folio(vmf->page);
 913         struct file *file = vmf->vma->vm_file;
 914         struct inode *inode = file_inode(file);
 915         struct afs_vnode *vnode = AFS_FS_I(inode);
 916         struct afs_file *af = file->private_data;
 917         unsigned long priv;
 918         vm_fault_t ret = VM_FAULT_RETRY;
 919
 920         _enter("{{%llx:%llu}},{%lx}", vnode->fid.vid, vnode->fid.vnode, folio_index(folio));
 921
 922         afs_validate(vnode, af->key);
 923
 924         sb_start_pagefault(inode->i_sb);
 925
 926         /* Wait for the page to be written to the cache before we allow it to
 927          * be modified.  We then assume the entire page will need writing back.
 928          */
 929 #ifdef CONFIG_AFS_FSCACHE
 930         if (folio_test_fscache(folio) &&
 931             folio_wait_fscache_killable(folio) < 0)
 932                 goto out;
 933 #endif
 934
 935         if (folio_wait_writeback_killable(folio))
 936                 goto out;
 937
 938         if (folio_lock_killable(folio) < 0)
 939                 goto out;
 940
 941         /* We mustn't change folio->private until writeback is complete as that
 942          * details the portion of the page we need to write back and we might
 943          * need to redirty the page if there's a problem.
 944          */
 945         if (folio_wait_writeback_killable(folio) < 0) {
 946                 folio_unlock(folio);
 947                 goto out;
 948         }
 949
 950         priv = afs_folio_dirty(folio, 0, folio_size(folio));
 951         priv = afs_folio_dirty_mmapped(priv);
 952         if (folio_test_private(folio)) {
 953                 folio_change_private(folio, (void *)priv);
 954                 trace_afs_folio_dirty(vnode, tracepoint_string("mkwrite+"), folio);
 955         } else {
 956                 folio_attach_private(folio, (void *)priv);
 957                 trace_afs_folio_dirty(vnode, tracepoint_string("mkwrite"), folio);
 958         }
 959         file_update_time(file);
 960
 961         ret = VM_FAULT_LOCKED;
 962 out:
 963         sb_end_pagefault(inode->i_sb);
 964         return ret;
 965 }
 966
 967 /*
 968  * Prune the keys cached for writeback.  The caller must hold vnode->wb_lock.
 969  */
 970 void afs_prune_wb_keys(struct afs_vnode *vnode)
 971 {
 972         LIST_HEAD(graveyard);
 973         struct afs_wb_key *wbk, *tmp;
 974
 975         /* Discard unused keys */
 976         spin_lock(&vnode->wb_lock);
 977
 978         if (!mapping_tagged(&vnode->netfs.inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
 979             !mapping_tagged(&vnode->netfs.inode.i_data, PAGECACHE_TAG_DIRTY)) {
 980                 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
 981                         if (refcount_read(&wbk->usage) == 1)
 982                                 list_move(&wbk->vnode_link, &graveyard);
 983                 }
 984         }
 985
 986         spin_unlock(&vnode->wb_lock);
 987
 988         while (!list_empty(&graveyard)) {
 989                 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
 990                 list_del(&wbk->vnode_link);
 991                 afs_put_wb_key(wbk);
 992         }
 993 }
 994
 995 /*
 996  * Clean up a page during invalidation.
 997  */
 998 int afs_launder_folio(struct folio *folio)
 999 {
1000         struct afs_vnode *vnode = AFS_FS_I(folio_inode(folio));
1001         struct iov_iter iter;
1002         struct bio_vec bv;
1003         unsigned long priv;
1004         unsigned int f, t;
1005         int ret = 0;
1006
1007         _enter("{%lx}", folio->index);
1008
1009         priv = (unsigned long)folio_get_private(folio);
1010         if (folio_clear_dirty_for_io(folio)) {
1011                 f = 0;
1012                 t = folio_size(folio);
1013                 if (folio_test_private(folio)) {
1014                         f = afs_folio_dirty_from(folio, priv);
1015                         t = afs_folio_dirty_to(folio, priv);
1016                 }
1017
1018                 bvec_set_folio(&bv, folio, t - f, f);
1019                 iov_iter_bvec(&iter, ITER_SOURCE, &bv, 1, bv.bv_len);
1020
1021                 trace_afs_folio_dirty(vnode, tracepoint_string("launder"), folio);
1022                 ret = afs_store_data(vnode, &iter, folio_pos(folio) + f, true);
1023         }
1024
1025         trace_afs_folio_dirty(vnode, tracepoint_string("laundered"), folio);
1026         folio_detach_private(folio);
1027         folio_wait_fscache(folio);
1028         return ret;
1029 }
1030
1031 /*
1032  * Deal with the completion of writing the data to the cache.
1033  */
1034 static void afs_write_to_cache_done(void *priv, ssize_t transferred_or_error,
1035                                     bool was_async)
1036 {
1037         struct afs_vnode *vnode = priv;
1038
1039         if (IS_ERR_VALUE(transferred_or_error) &&
1040             transferred_or_error != -ENOBUFS)
1041                 afs_invalidate_cache(vnode, 0);
1042 }
1043
1044 /*
1045  * Save the write to the cache also.
1046  */
1047 static void afs_write_to_cache(struct afs_vnode *vnode,
1048                                loff_t start, size_t len, loff_t i_size,
1049                                bool caching)
1050 {
1051         fscache_write_to_cache(afs_vnode_cache(vnode),
1052                                vnode->netfs.inode.i_mapping, start, len, i_size,
1053                                afs_write_to_cache_done, vnode, caching);
1054 }