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                 for (i = 0; i < req->nr_pages; i++)
 195                         if (req->pages[i])
 196                                 put_page(req->pages[i]);
 197                 if (req->pages != req->array)
 198                         kfree(req->pages);
 199                 kfree(req);
 200         }
 201 }
 202
 203 #ifdef CONFIG_AFS_FSCACHE
 204 /*
 205  * deal with notification that a page was read from the cache
 206  */
 207 static void afs_file_readpage_read_complete(struct page *page,
 208                                             void *data,
 209                                             int error)
 210 {
 211         _enter("%p,%p,%d", page, data, error);
 212
 213         /* if the read completes with an error, we just unlock the page and let
 214          * the VM reissue the readpage */
 215         if (!error)
 216                 SetPageUptodate(page);
 217         unlock_page(page);
 218 }
 219 #endif
 220
 221 /*
 222  * Fetch file data from the volume.
 223  */
 224 int afs_fetch_data(struct afs_vnode *vnode, struct key *key, struct afs_read *desc)
 225 {
 226         struct afs_fs_cursor fc;
 227         struct afs_status_cb *scb;
 228         int ret;
 229
 230         _enter("%s{%llx:%llu.%u},%x,,,",
 231                vnode->volume->name,
 232                vnode->fid.vid,
 233                vnode->fid.vnode,
 234                vnode->fid.unique,
 235                key_serial(key));
 236
 237         scb = kzalloc(sizeof(struct afs_status_cb), GFP_KERNEL);
 238         if (!scb)
 239                 return -ENOMEM;
 240
 241         ret = -ERESTARTSYS;
 242         if (afs_begin_vnode_operation(&fc, vnode, key, true)) {
 243                 afs_dataversion_t data_version = vnode->status.data_version;
 244
 245                 while (afs_select_fileserver(&fc)) {
 246                         fc.cb_break = afs_calc_vnode_cb_break(vnode);
 247                         afs_fs_fetch_data(&fc, scb, desc);
 248                 }
 249
 250                 afs_check_for_remote_deletion(&fc, vnode);
 251                 afs_vnode_commit_status(&fc, vnode, fc.cb_break,
 252                                         &data_version, scb);
 253                 ret = afs_end_vnode_operation(&fc);
 254         }
 255
 256         if (ret == 0) {
 257                 afs_stat_v(vnode, n_fetches);
 258                 atomic_long_add(desc->actual_len,
 259                                 &afs_v2net(vnode)->n_fetch_bytes);
 260         }
 261
 262         kfree(scb);
 263         _leave(" = %d", ret);
 264         return ret;
 265 }
 266
 267 /*
 268  * read page from file, directory or symlink, given a key to use
 269  */
 270 int afs_page_filler(void *data, struct page *page)
 271 {
 272         struct inode *inode = page->mapping->host;
 273         struct afs_vnode *vnode = AFS_FS_I(inode);
 274         struct afs_read *req;
 275         struct key *key = data;
 276         int ret;
 277
 278         _enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
 279
 280         BUG_ON(!PageLocked(page));
 281
 282         ret = -ESTALE;
 283         if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
 284                 goto error;
 285
 286         /* is it cached? */
 287 #ifdef CONFIG_AFS_FSCACHE
 288         ret = fscache_read_or_alloc_page(vnode->cache,
 289                                          page,
 290                                          afs_file_readpage_read_complete,
 291                                          NULL,
 292                                          GFP_KERNEL);
 293 #else
 294         ret = -ENOBUFS;
 295 #endif
 296         switch (ret) {
 297                 /* read BIO submitted (page in cache) */
 298         case 0:
 299                 break;
 300
 301                 /* page not yet cached */
 302         case -ENODATA:
 303                 _debug("cache said ENODATA");
 304                 goto go_on;
 305
 306                 /* page will not be cached */
 307         case -ENOBUFS:
 308                 _debug("cache said ENOBUFS");
 309
 310                 /* fall through */
 311         default:
 312         go_on:
 313                 req = kzalloc(sizeof(struct afs_read) + sizeof(struct page *),
 314                               GFP_KERNEL);
 315                 if (!req)
 316                         goto enomem;
 317
 318                 /* We request a full page.  If the page is a partial one at the
 319                  * end of the file, the server will return a short read and the
 320                  * unmarshalling code will clear the unfilled space.
 321                  */
 322                 refcount_set(&req->usage, 1);
 323                 req->pos = (loff_t)page->index << PAGE_SHIFT;
 324                 req->len = PAGE_SIZE;
 325                 req->nr_pages = 1;
 326                 req->pages = req->array;
 327                 req->pages[0] = page;
 328                 get_page(page);
 329
 330                 /* read the contents of the file from the server into the
 331                  * page */
 332                 ret = afs_fetch_data(vnode, key, req);
 333                 afs_put_read(req);
 334
 335                 if (ret < 0) {
 336                         if (ret == -ENOENT) {
 337                                 _debug("got NOENT from server"
 338                                        " - marking file deleted and stale");
 339                                 set_bit(AFS_VNODE_DELETED, &vnode->flags);
 340                                 ret = -ESTALE;
 341                         }
 342
 343 #ifdef CONFIG_AFS_FSCACHE
 344                         fscache_uncache_page(vnode->cache, page);
 345 #endif
 346                         BUG_ON(PageFsCache(page));
 347
 348                         if (ret == -EINTR ||
 349                             ret == -ENOMEM ||
 350                             ret == -ERESTARTSYS ||
 351                             ret == -EAGAIN)
 352                                 goto error;
 353                         goto io_error;
 354                 }
 355
 356                 SetPageUptodate(page);
 357
 358                 /* send the page to the cache */
 359 #ifdef CONFIG_AFS_FSCACHE
 360                 if (PageFsCache(page) &&
 361                     fscache_write_page(vnode->cache, page, vnode->status.size,
 362                                        GFP_KERNEL) != 0) {
 363                         fscache_uncache_page(vnode->cache, page);
 364                         BUG_ON(PageFsCache(page));
 365                 }
 366 #endif
 367                 unlock_page(page);
 368         }
 369
 370         _leave(" = 0");
 371         return 0;
 372
 373 io_error:
 374         SetPageError(page);
 375         goto error;
 376 enomem:
 377         ret = -ENOMEM;
 378 error:
 379         unlock_page(page);
 380         _leave(" = %d", ret);
 381         return ret;
 382 }
 383
 384 /*
 385  * read page from file, directory or symlink, given a file to nominate the key
 386  * to be used
 387  */
 388 static int afs_readpage(struct file *file, struct page *page)
 389 {
 390         struct key *key;
 391         int ret;
 392
 393         if (file) {
 394                 key = afs_file_key(file);
 395                 ASSERT(key != NULL);
 396                 ret = afs_page_filler(key, page);
 397         } else {
 398                 struct inode *inode = page->mapping->host;
 399                 key = afs_request_key(AFS_FS_S(inode->i_sb)->cell);
 400                 if (IS_ERR(key)) {
 401                         ret = PTR_ERR(key);
 402                 } else {
 403                         ret = afs_page_filler(key, page);
 404                         key_put(key);
 405                 }
 406         }
 407         return ret;
 408 }
 409
 410 /*
 411  * Make pages available as they're filled.
 412  */
 413 static void afs_readpages_page_done(struct afs_read *req)
 414 {
 415 #ifdef CONFIG_AFS_FSCACHE
 416         struct afs_vnode *vnode = req->vnode;
 417 #endif
 418         struct page *page = req->pages[req->index];
 419
 420         req->pages[req->index] = NULL;
 421         SetPageUptodate(page);
 422
 423         /* send the page to the cache */
 424 #ifdef CONFIG_AFS_FSCACHE
 425         if (PageFsCache(page) &&
 426             fscache_write_page(vnode->cache, page, vnode->status.size,
 427                                GFP_KERNEL) != 0) {
 428                 fscache_uncache_page(vnode->cache, page);
 429                 BUG_ON(PageFsCache(page));
 430         }
 431 #endif
 432         unlock_page(page);
 433         put_page(page);
 434 }
 435
 436 /*
 437  * Read a contiguous set of pages.
 438  */
 439 static int afs_readpages_one(struct file *file, struct address_space *mapping,
 440                              struct list_head *pages)
 441 {
 442         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 443         struct afs_read *req;
 444         struct list_head *p;
 445         struct page *first, *page;
 446         struct key *key = afs_file_key(file);
 447         pgoff_t index;
 448         int ret, n, i;
 449
 450         /* Count the number of contiguous pages at the front of the list.  Note
 451          * that the list goes prev-wards rather than next-wards.
 452          */
 453         first = lru_to_page(pages);
 454         index = first->index + 1;
 455         n = 1;
 456         for (p = first->lru.prev; p != pages; p = p->prev) {
 457                 page = list_entry(p, struct page, lru);
 458                 if (page->index != index)
 459                         break;
 460                 index++;
 461                 n++;
 462         }
 463
 464         req = kzalloc(sizeof(struct afs_read) + sizeof(struct page *) * n,
 465                       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 }