fs/afs/file.c

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