fs/afs/file.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* AFS filesystem file handling
   3  *
   4  * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/init.h>
  11 #include <linux/fs.h>
  12 #include <linux/pagemap.h>
  13 #include <linux/writeback.h>
  14 #include <linux/gfp.h>
  15 #include <linux/task_io_accounting_ops.h>
  16 #include <linux/mm.h>
  17 #include "internal.h"
  18
  19 static int afs_file_mmap(struct file *file, struct vm_area_struct *vma);
  20 static int afs_readpage(struct file *file, struct page *page);
  21 static void afs_invalidatepage(struct page *page, unsigned int offset,
  22                                unsigned int length);
  23 static int afs_releasepage(struct page *page, gfp_t gfp_flags);
  24
  25 static int afs_readpages(struct file *filp, struct address_space *mapping,
  26                          struct list_head *pages, unsigned nr_pages);
  27
  28 const struct file_operations afs_file_operations = {
  29         .open           = afs_open,
  30         .release        = afs_release,
  31         .llseek         = generic_file_llseek,
  32         .read_iter      = generic_file_read_iter,
  33         .write_iter     = afs_file_write,
  34         .mmap           = afs_file_mmap,
  35         .splice_read    = generic_file_splice_read,
  36         .fsync          = afs_fsync,
  37         .lock           = afs_lock,
  38         .flock          = afs_flock,
  39 };
  40
  41 const struct inode_operations afs_file_inode_operations = {
  42         .getattr        = afs_getattr,
  43         .setattr        = afs_setattr,
  44         .permission     = afs_permission,
  45         .listxattr      = afs_listxattr,
  46 };
  47
  48 const struct address_space_operations afs_fs_aops = {
  49         .readpage       = afs_readpage,
  50         .readpages      = afs_readpages,
  51         .set_page_dirty = afs_set_page_dirty,
  52         .launder_page   = afs_launder_page,
  53         .releasepage    = afs_releasepage,
  54         .invalidatepage = afs_invalidatepage,
  55         .write_begin    = afs_write_begin,
  56         .write_end      = afs_write_end,
  57         .writepage      = afs_writepage,
  58         .writepages     = afs_writepages,
  59 };
  60
  61 static const struct vm_operations_struct afs_vm_ops = {
  62         .fault          = filemap_fault,
  63         .map_pages      = filemap_map_pages,
  64         .page_mkwrite   = afs_page_mkwrite,
  65 };
  66
  67 /*
  68  * Discard a pin on a writeback key.
  69  */
  70 void afs_put_wb_key(struct afs_wb_key *wbk)
  71 {
  72         if (refcount_dec_and_test(&wbk->usage)) {
  73                 key_put(wbk->key);
  74                 kfree(wbk);
  75         }
  76 }
  77
  78 /*
  79  * Cache key for writeback.
  80  */
  81 int afs_cache_wb_key(struct afs_vnode *vnode, struct afs_file *af)
  82 {
  83         struct afs_wb_key *wbk, *p;
  84
  85         wbk = kzalloc(sizeof(struct afs_wb_key), GFP_KERNEL);
  86         if (!wbk)
  87                 return -ENOMEM;
  88         refcount_set(&wbk->usage, 2);
  89         wbk->key = af->key;
  90
  91         spin_lock(&vnode->wb_lock);
  92         list_for_each_entry(p, &vnode->wb_keys, vnode_link) {
  93                 if (p->key == wbk->key)
  94                         goto found;
  95         }
  96
  97         key_get(wbk->key);
  98         list_add_tail(&wbk->vnode_link, &vnode->wb_keys);
  99         spin_unlock(&vnode->wb_lock);
 100         af->wb = wbk;
 101         return 0;
 102
 103 found:
 104         refcount_inc(&p->usage);
 105         spin_unlock(&vnode->wb_lock);
 106         af->wb = p;
 107         kfree(wbk);
 108         return 0;
 109 }
 110
 111 /*
 112  * open an AFS file or directory and attach a key to it
 113  */
 114 int afs_open(struct inode *inode, struct file *file)
 115 {
 116         struct afs_vnode *vnode = AFS_FS_I(inode);
 117         struct afs_file *af;
 118         struct key *key;
 119         int ret;
 120
 121         _enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);
 122
 123         key = afs_request_key(vnode->volume->cell);
 124         if (IS_ERR(key)) {
 125                 ret = PTR_ERR(key);
 126                 goto error;
 127         }
 128
 129         af = kzalloc(sizeof(*af), GFP_KERNEL);
 130         if (!af) {
 131                 ret = -ENOMEM;
 132                 goto error_key;
 133         }
 134         af->key = key;
 135
 136         ret = afs_validate(vnode, key);
 137         if (ret < 0)
 138                 goto error_af;
 139
 140         if (file->f_mode & FMODE_WRITE) {
 141                 ret = afs_cache_wb_key(vnode, af);
 142                 if (ret < 0)
 143                         goto error_af;
 144         }
 145
 146         if (file->f_flags & O_TRUNC)
 147                 set_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
 148
 149         file->private_data = af;
 150         _leave(" = 0");
 151         return 0;
 152
 153 error_af:
 154         kfree(af);
 155 error_key:
 156         key_put(key);
 157 error:
 158         _leave(" = %d", ret);
 159         return ret;
 160 }
 161
 162 /*
 163  * release an AFS file or directory and discard its key
 164  */
 165 int afs_release(struct inode *inode, struct file *file)
 166 {
 167         struct afs_vnode *vnode = AFS_FS_I(inode);
 168         struct afs_file *af = file->private_data;
 169         int ret = 0;
 170
 171         _enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);
 172
 173         if ((file->f_mode & FMODE_WRITE))
 174                 ret = vfs_fsync(file, 0);
 175
 176         file->private_data = NULL;
 177         if (af->wb)
 178                 afs_put_wb_key(af->wb);
 179         key_put(af->key);
 180         kfree(af);
 181         afs_prune_wb_keys(vnode);
 182         _leave(" = %d", ret);
 183         return ret;
 184 }
 185
 186 /*
 187  * Dispose of a ref to a read record.
 188  */
 189 void afs_put_read(struct afs_read *req)
 190 {
 191         int i;
 192
 193         if (refcount_dec_and_test(&req->usage)) {
 194                 if (req->pages) {
 195                         for (i = 0; i < req->nr_pages; i++)
 196                                 if (req->pages[i])
 197                                         put_page(req->pages[i]);
 198                         if (req->pages != req->array)
 199                                 kfree(req->pages);
 200                 }
 201                 kfree(req);
 202         }
 203 }
 204
 205 #ifdef CONFIG_AFS_FSCACHE
 206 /*
 207  * deal with notification that a page was read from the cache
 208  */
 209 static void afs_file_readpage_read_complete(struct page *page,
 210                                             void *data,
 211                                             int error)
 212 {
 213         _enter("%p,%p,%d", page, data, error);
 214
 215         /* if the read completes with an error, we just unlock the page and let
 216          * the VM reissue the readpage */
 217         if (!error)
 218                 SetPageUptodate(page);
 219         unlock_page(page);
 220 }
 221 #endif
 222
 223 /*
 224  * Fetch file data from the volume.
 225  */
 226 int afs_fetch_data(struct afs_vnode *vnode, struct key *key, struct afs_read *req)
 227 {
 228         struct afs_fs_cursor fc;
 229         struct afs_status_cb *scb;
 230         int ret;
 231
 232         _enter("%s{%llx:%llu.%u},%x,,,",
 233                vnode->volume->name,
 234                vnode->fid.vid,
 235                vnode->fid.vnode,
 236                vnode->fid.unique,
 237                key_serial(key));
 238
 239         scb = kzalloc(sizeof(struct afs_status_cb), GFP_KERNEL);
 240         if (!scb)
 241                 return -ENOMEM;
 242
 243         ret = -ERESTARTSYS;
 244         if (afs_begin_vnode_operation(&fc, vnode, key, true)) {
 245                 afs_dataversion_t data_version = vnode->status.data_version;
 246
 247                 while (afs_select_fileserver(&fc)) {
 248                         fc.cb_break = afs_calc_vnode_cb_break(vnode);
 249                         afs_fs_fetch_data(&fc, scb, req);
 250                 }
 251
 252                 afs_check_for_remote_deletion(&fc, vnode);
 253                 afs_vnode_commit_status(&fc, vnode, fc.cb_break,
 254                                         &data_version, scb);
 255                 ret = afs_end_vnode_operation(&fc);
 256         }
 257
 258         if (ret == 0) {
 259                 afs_stat_v(vnode, n_fetches);
 260                 atomic_long_add(req->actual_len,
 261                                 &afs_v2net(vnode)->n_fetch_bytes);
 262         }
 263
 264         kfree(scb);
 265         _leave(" = %d", ret);
 266         return ret;
 267 }
 268
 269 /*
 270  * read page from file, directory or symlink, given a key to use
 271  */
 272 int afs_page_filler(void *data, struct page *page)
 273 {
 274         struct inode *inode = page->mapping->host;
 275         struct afs_vnode *vnode = AFS_FS_I(inode);
 276         struct afs_read *req;
 277         struct key *key = data;
 278         int ret;
 279
 280         _enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
 281
 282         BUG_ON(!PageLocked(page));
 283
 284         ret = -ESTALE;
 285         if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
 286                 goto error;
 287
 288         /* is it cached? */
 289 #ifdef CONFIG_AFS_FSCACHE
 290         ret = fscache_read_or_alloc_page(vnode->cache,
 291                                          page,
 292                                          afs_file_readpage_read_complete,
 293                                          NULL,
 294                                          GFP_KERNEL);
 295 #else
 296         ret = -ENOBUFS;
 297 #endif
 298         switch (ret) {
 299                 /* read BIO submitted (page in cache) */
 300         case 0:
 301                 break;
 302
 303                 /* page not yet cached */
 304         case -ENODATA:
 305                 _debug("cache said ENODATA");
 306                 goto go_on;
 307
 308                 /* page will not be cached */
 309         case -ENOBUFS:
 310                 _debug("cache said ENOBUFS");
 311
 312                 /* fall through */
 313         default:
 314         go_on:
 315                 req = kzalloc(struct_size(req, array, 1), GFP_KERNEL);
 316                 if (!req)
 317                         goto enomem;
 318
 319                 /* We request a full page.  If the page is a partial one at the
 320                  * end of the file, the server will return a short read and the
 321                  * unmarshalling code will clear the unfilled space.
 322                  */
 323                 refcount_set(&req->usage, 1);
 324                 req->pos = (loff_t)page->index << PAGE_SHIFT;
 325                 req->len = PAGE_SIZE;
 326                 req->nr_pages = 1;
 327                 req->pages = req->array;
 328                 req->pages[0] = page;
 329                 get_page(page);
 330
 331                 /* read the contents of the file from the server into the
 332                  * page */
 333                 ret = afs_fetch_data(vnode, key, req);
 334                 afs_put_read(req);
 335
 336                 if (ret < 0) {
 337                         if (ret == -ENOENT) {
 338                                 _debug("got NOENT from server"
 339                                        " - marking file deleted and stale");
 340                                 set_bit(AFS_VNODE_DELETED, &vnode->flags);
 341                                 ret = -ESTALE;
 342                         }
 343
 344 #ifdef CONFIG_AFS_FSCACHE
 345                         fscache_uncache_page(vnode->cache, page);
 346 #endif
 347                         BUG_ON(PageFsCache(page));
 348
 349                         if (ret == -EINTR ||
 350                             ret == -ENOMEM ||
 351                             ret == -ERESTARTSYS ||
 352                             ret == -EAGAIN)
 353                                 goto error;
 354                         goto io_error;
 355                 }
 356
 357                 SetPageUptodate(page);
 358
 359                 /* send the page to the cache */
 360 #ifdef CONFIG_AFS_FSCACHE
 361                 if (PageFsCache(page) &&
 362                     fscache_write_page(vnode->cache, page, vnode->status.size,
 363                                        GFP_KERNEL) != 0) {
 364                         fscache_uncache_page(vnode->cache, page);
 365                         BUG_ON(PageFsCache(page));
 366                 }
 367 #endif
 368                 unlock_page(page);
 369         }
 370
 371         _leave(" = 0");
 372         return 0;
 373
 374 io_error:
 375         SetPageError(page);
 376         goto error;
 377 enomem:
 378         ret = -ENOMEM;
 379 error:
 380         unlock_page(page);
 381         _leave(" = %d", ret);
 382         return ret;
 383 }
 384
 385 /*
 386  * read page from file, directory or symlink, given a file to nominate the key
 387  * to be used
 388  */
 389 static int afs_readpage(struct file *file, struct page *page)
 390 {
 391         struct key *key;
 392         int ret;
 393
 394         if (file) {
 395                 key = afs_file_key(file);
 396                 ASSERT(key != NULL);
 397                 ret = afs_page_filler(key, page);
 398         } else {
 399                 struct inode *inode = page->mapping->host;
 400                 key = afs_request_key(AFS_FS_S(inode->i_sb)->cell);
 401                 if (IS_ERR(key)) {
 402                         ret = PTR_ERR(key);
 403                 } else {
 404                         ret = afs_page_filler(key, page);
 405                         key_put(key);
 406                 }
 407         }
 408         return ret;
 409 }
 410
 411 /*
 412  * Make pages available as they're filled.
 413  */
 414 static void afs_readpages_page_done(struct afs_read *req)
 415 {
 416 #ifdef CONFIG_AFS_FSCACHE
 417         struct afs_vnode *vnode = req->vnode;
 418 #endif
 419         struct page *page = req->pages[req->index];
 420
 421         req->pages[req->index] = NULL;
 422         SetPageUptodate(page);
 423
 424         /* send the page to the cache */
 425 #ifdef CONFIG_AFS_FSCACHE
 426         if (PageFsCache(page) &&
 427             fscache_write_page(vnode->cache, page, vnode->status.size,
 428                                GFP_KERNEL) != 0) {
 429                 fscache_uncache_page(vnode->cache, page);
 430                 BUG_ON(PageFsCache(page));
 431         }
 432 #endif
 433         unlock_page(page);
 434         put_page(page);
 435 }
 436
 437 /*
 438  * Read a contiguous set of pages.
 439  */
 440 static int afs_readpages_one(struct file *file, struct address_space *mapping,
 441                              struct list_head *pages)
 442 {
 443         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 444         struct afs_read *req;
 445         struct list_head *p;
 446         struct page *first, *page;
 447         struct key *key = afs_file_key(file);
 448         pgoff_t index;
 449         int ret, n, i;
 450
 451         /* Count the number of contiguous pages at the front of the list.  Note
 452          * that the list goes prev-wards rather than next-wards.
 453          */
 454         first = lru_to_page(pages);
 455         index = first->index + 1;
 456         n = 1;
 457         for (p = first->lru.prev; p != pages; p = p->prev) {
 458                 page = list_entry(p, struct page, lru);
 459                 if (page->index != index)
 460                         break;
 461                 index++;
 462                 n++;
 463         }
 464
 465         req = kzalloc(struct_size(req, array, n), GFP_NOFS);
 466         if (!req)
 467                 return -ENOMEM;
 468
 469         refcount_set(&req->usage, 1);
 470         req->vnode = vnode;
 471         req->page_done = afs_readpages_page_done;
 472         req->pos = first->index;
 473         req->pos <<= PAGE_SHIFT;
 474         req->pages = req->array;
 475
 476         /* Transfer the pages to the request.  We add them in until one fails
 477          * to add to the LRU and then we stop (as that'll make a hole in the
 478          * contiguous run.
 479          *
 480          * Note that it's possible for the file size to change whilst we're
 481          * doing this, but we rely on the server returning less than we asked
 482          * for if the file shrank.  We also rely on this to deal with a partial
 483          * page at the end of the file.
 484          */
 485         do {
 486                 page = lru_to_page(pages);
 487                 list_del(&page->lru);
 488                 index = page->index;
 489                 if (add_to_page_cache_lru(page, mapping, index,
 490                                           readahead_gfp_mask(mapping))) {
 491 #ifdef CONFIG_AFS_FSCACHE
 492                         fscache_uncache_page(vnode->cache, page);
 493 #endif
 494                         put_page(page);
 495                         break;
 496                 }
 497
 498                 req->pages[req->nr_pages++] = page;
 499                 req->len += PAGE_SIZE;
 500         } while (req->nr_pages < n);
 501
 502         if (req->nr_pages == 0) {
 503                 kfree(req);
 504                 return 0;
 505         }
 506
 507         ret = afs_fetch_data(vnode, key, req);
 508         if (ret < 0)
 509                 goto error;
 510
 511         task_io_account_read(PAGE_SIZE * req->nr_pages);
 512         afs_put_read(req);
 513         return 0;
 514
 515 error:
 516         if (ret == -ENOENT) {
 517                 _debug("got NOENT from server"
 518                        " - marking file deleted and stale");
 519                 set_bit(AFS_VNODE_DELETED, &vnode->flags);
 520                 ret = -ESTALE;
 521         }
 522
 523         for (i = 0; i < req->nr_pages; i++) {
 524                 page = req->pages[i];
 525                 if (page) {
 526 #ifdef CONFIG_AFS_FSCACHE
 527                         fscache_uncache_page(vnode->cache, page);
 528 #endif
 529                         SetPageError(page);
 530                         unlock_page(page);
 531                 }
 532         }
 533
 534         afs_put_read(req);
 535         return ret;
 536 }
 537
 538 /*
 539  * read a set of pages
 540  */
 541 static int afs_readpages(struct file *file, struct address_space *mapping,
 542                          struct list_head *pages, unsigned nr_pages)
 543 {
 544         struct key *key = afs_file_key(file);
 545         struct afs_vnode *vnode;
 546         int ret = 0;
 547
 548         _enter("{%d},{%lu},,%d",
 549                key_serial(key), mapping->host->i_ino, nr_pages);
 550
 551         ASSERT(key != NULL);
 552
 553         vnode = AFS_FS_I(mapping->host);
 554         if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
 555                 _leave(" = -ESTALE");
 556                 return -ESTALE;
 557         }
 558
 559         /* attempt to read as many of the pages as possible */
 560 #ifdef CONFIG_AFS_FSCACHE
 561         ret = fscache_read_or_alloc_pages(vnode->cache,
 562                                           mapping,
 563                                           pages,
 564                                           &nr_pages,
 565                                           afs_file_readpage_read_complete,
 566                                           NULL,
 567                                           mapping_gfp_mask(mapping));
 568 #else
 569         ret = -ENOBUFS;
 570 #endif
 571
 572         switch (ret) {
 573                 /* all pages are being read from the cache */
 574         case 0:
 575                 BUG_ON(!list_empty(pages));
 576                 BUG_ON(nr_pages != 0);
 577                 _leave(" = 0 [reading all]");
 578                 return 0;
 579
 580                 /* there were pages that couldn't be read from the cache */
 581         case -ENODATA:
 582         case -ENOBUFS:
 583                 break;
 584
 585                 /* other error */
 586         default:
 587                 _leave(" = %d", ret);
 588                 return ret;
 589         }
 590
 591         while (!list_empty(pages)) {
 592                 ret = afs_readpages_one(file, mapping, pages);
 593                 if (ret < 0)
 594                         break;
 595         }
 596
 597         _leave(" = %d [netting]", ret);
 598         return ret;
 599 }
 600
 601 /*
 602  * invalidate part or all of a page
 603  * - release a page and clean up its private data if offset is 0 (indicating
 604  *   the entire page)
 605  */
 606 static void afs_invalidatepage(struct page *page, unsigned int offset,
 607                                unsigned int length)
 608 {
 609         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 610         unsigned long priv;
 611
 612         _enter("{%lu},%u,%u", page->index, offset, length);
 613
 614         BUG_ON(!PageLocked(page));
 615
 616         /* we clean up only if the entire page is being invalidated */
 617         if (offset == 0 && length == PAGE_SIZE) {
 618 #ifdef CONFIG_AFS_FSCACHE
 619                 if (PageFsCache(page)) {
 620                         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 621                         fscache_wait_on_page_write(vnode->cache, page);
 622                         fscache_uncache_page(vnode->cache, page);
 623                 }
 624 #endif
 625
 626                 if (PagePrivate(page)) {
 627                         priv = page_private(page);
 628                         trace_afs_page_dirty(vnode, tracepoint_string("inval"),
 629                                              page->index, priv);
 630                         set_page_private(page, 0);
 631                         ClearPagePrivate(page);
 632                 }
 633         }
 634
 635         _leave("");
 636 }
 637
 638 /*
 639  * release a page and clean up its private state if it's not busy
 640  * - return true if the page can now be released, false if not
 641  */
 642 static int afs_releasepage(struct page *page, gfp_t gfp_flags)
 643 {
 644         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 645         unsigned long priv;
 646
 647         _enter("{{%llx:%llu}[%lu],%lx},%x",
 648                vnode->fid.vid, vnode->fid.vnode, page->index, page->flags,
 649                gfp_flags);
 650
 651         /* deny if page is being written to the cache and the caller hasn't
 652          * elected to wait */
 653 #ifdef CONFIG_AFS_FSCACHE
 654         if (!fscache_maybe_release_page(vnode->cache, page, gfp_flags)) {
 655                 _leave(" = F [cache busy]");
 656                 return 0;
 657         }
 658 #endif
 659
 660         if (PagePrivate(page)) {
 661                 priv = page_private(page);
 662                 trace_afs_page_dirty(vnode, tracepoint_string("rel"),
 663                                      page->index, priv);
 664                 set_page_private(page, 0);
 665                 ClearPagePrivate(page);
 666         }
 667
 668         /* indicate that the page can be released */
 669         _leave(" = T");
 670         return 1;
 671 }
 672
 673 /*
 674  * Handle setting up a memory mapping on an AFS file.
 675  */
 676 static int afs_file_mmap(struct file *file, struct vm_area_struct *vma)
 677 {
 678         int ret;
 679
 680         ret = generic_file_mmap(file, vma);
 681         if (ret == 0)
 682                 vma->vm_ops = &afs_vm_ops;
 683         return ret;
 684 }