fs/ecryptfs/mmap.c

   1 /**
   2  * eCryptfs: Linux filesystem encryption layer
   3  * This is where eCryptfs coordinates the symmetric encryption and
   4  * decryption of the file data as it passes between the lower
   5  * encrypted file and the upper decrypted file.
   6  *
   7  * Copyright (C) 1997-2003 Erez Zadok
   8  * Copyright (C) 2001-2003 Stony Brook University
   9  * Copyright (C) 2004-2006 International Business Machines Corp.
  10  *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License as
  14  * published by the Free Software Foundation; either version 2 of the
  15  * License, or (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful, but
  18  * WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20  * General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  25  * 02111-1307, USA.
  26  */
  27
  28 #include <linux/pagemap.h>
  29 #include <linux/writeback.h>
  30 #include <linux/page-flags.h>
  31 #include <linux/mount.h>
  32 #include <linux/file.h>
  33 #include <linux/crypto.h>
  34 #include <linux/scatterlist.h>
  35 #include "ecryptfs_kernel.h"
  36
  37 struct kmem_cache *ecryptfs_lower_page_cache;
  38
  39 /**
  40  * ecryptfs_get1page
  41  *
  42  * Get one page from cache or lower f/s, return error otherwise.
  43  *
  44  * Returns unlocked and up-to-date page (if ok), with increased
  45  * refcnt.
  46  */
  47 static struct page *ecryptfs_get1page(struct file *file, int index)
  48 {
  49         struct page *page;
  50         struct dentry *dentry;
  51         struct inode *inode;
  52         struct address_space *mapping;
  53
  54         dentry = file->f_path.dentry;
  55         inode = dentry->d_inode;
  56         mapping = inode->i_mapping;
  57         page = read_cache_page(mapping, index,
  58                                (filler_t *)mapping->a_ops->readpage,
  59                                (void *)file);
  60         if (IS_ERR(page))
  61                 goto out;
  62         wait_on_page_locked(page);
  63 out:
  64         return page;
  65 }
  66
  67 static
  68 int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros);
  69
  70 /**
  71  * ecryptfs_fill_zeros
  72  * @file: The ecryptfs file
  73  * @new_length: The new length of the data in the underlying file;
  74  *              everything between the prior end of the file and the
  75  *              new end of the file will be filled with zero's.
  76  *              new_length must be greater than  current length
  77  *
  78  * Function for handling lseek-ing past the end of the file.
  79  *
  80  * This function does not support shrinking, only growing a file.
  81  *
  82  * Returns zero on success; non-zero otherwise.
  83  */
  84 int ecryptfs_fill_zeros(struct file *file, loff_t new_length)
  85 {
  86         int rc = 0;
  87         struct dentry *dentry = file->f_path.dentry;
  88         struct inode *inode = dentry->d_inode;
  89         pgoff_t old_end_page_index = 0;
  90         pgoff_t index = old_end_page_index;
  91         int old_end_pos_in_page = -1;
  92         pgoff_t new_end_page_index;
  93         int new_end_pos_in_page;
  94         loff_t cur_length = i_size_read(inode);
  95
  96         if (cur_length != 0) {
  97                 index = old_end_page_index =
  98                     ((cur_length - 1) >> PAGE_CACHE_SHIFT);
  99                 old_end_pos_in_page = ((cur_length - 1) & ~PAGE_CACHE_MASK);
 100         }
 101         new_end_page_index = ((new_length - 1) >> PAGE_CACHE_SHIFT);
 102         new_end_pos_in_page = ((new_length - 1) & ~PAGE_CACHE_MASK);
 103         ecryptfs_printk(KERN_DEBUG, "old_end_page_index = [0x%.16x]; "
 104                         "old_end_pos_in_page = [%d]; "
 105                         "new_end_page_index = [0x%.16x]; "
 106                         "new_end_pos_in_page = [%d]\n",
 107                         old_end_page_index, old_end_pos_in_page,
 108                         new_end_page_index, new_end_pos_in_page);
 109         if (old_end_page_index == new_end_page_index) {
 110                 /* Start and end are in the same page; we just need to
 111                  * set a portion of the existing page to zero's */
 112                 rc = write_zeros(file, index, (old_end_pos_in_page + 1),
 113                                  (new_end_pos_in_page - old_end_pos_in_page));
 114                 if (rc)
 115                         ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
 116                                         "index=[0x%.16x], "
 117                                         "old_end_pos_in_page=[d], "
 118                                         "(PAGE_CACHE_SIZE - new_end_pos_in_page"
 119                                         "=[%d]"
 120                                         ")=[d]) returned [%d]\n", file, index,
 121                                         old_end_pos_in_page,
 122                                         new_end_pos_in_page,
 123                                         (PAGE_CACHE_SIZE - new_end_pos_in_page),
 124                                         rc);
 125                 goto out;
 126         }
 127         /* Fill the remainder of the previous last page with zeros */
 128         rc = write_zeros(file, index, (old_end_pos_in_page + 1),
 129                          ((PAGE_CACHE_SIZE - 1) - old_end_pos_in_page));
 130         if (rc) {
 131                 ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
 132                                 "index=[0x%.16x], old_end_pos_in_page=[d], "
 133                                 "(PAGE_CACHE_SIZE - old_end_pos_in_page)=[d]) "
 134                                 "returned [%d]\n", file, index,
 135                                 old_end_pos_in_page,
 136                                 (PAGE_CACHE_SIZE - old_end_pos_in_page), rc);
 137                 goto out;
 138         }
 139         index++;
 140         while (index < new_end_page_index) {
 141                 /* Fill all intermediate pages with zeros */
 142                 rc = write_zeros(file, index, 0, PAGE_CACHE_SIZE);
 143                 if (rc) {
 144                         ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
 145                                         "index=[0x%.16x], "
 146                                         "old_end_pos_in_page=[d], "
 147                                         "(PAGE_CACHE_SIZE - new_end_pos_in_page"
 148                                         "=[%d]"
 149                                         ")=[d]) returned [%d]\n", file, index,
 150                                         old_end_pos_in_page,
 151                                         new_end_pos_in_page,
 152                                         (PAGE_CACHE_SIZE - new_end_pos_in_page),
 153                                         rc);
 154                         goto out;
 155                 }
 156                 index++;
 157         }
 158         /* Fill the portion at the beginning of the last new page with
 159          * zero's */
 160         rc = write_zeros(file, index, 0, (new_end_pos_in_page + 1));
 161         if (rc) {
 162                 ecryptfs_printk(KERN_ERR, "write_zeros(file="
 163                                 "[%p], index=[0x%.16x], 0, "
 164                                 "new_end_pos_in_page=[%d]"
 165                                 "returned [%d]\n", file, index,
 166                                 new_end_pos_in_page, rc);
 167                 goto out;
 168         }
 169 out:
 170         return rc;
 171 }
 172
 173 /**
 174  * ecryptfs_writepage
 175  * @page: Page that is locked before this call is made
 176  *
 177  * Returns zero on success; non-zero otherwise
 178  */
 179 static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
 180 {
 181         struct ecryptfs_page_crypt_context ctx;
 182         int rc;
 183
 184         ctx.page = page;
 185         ctx.mode = ECRYPTFS_WRITEPAGE_MODE;
 186         ctx.param.wbc = wbc;
 187         rc = ecryptfs_encrypt_page(&ctx);
 188         if (rc) {
 189                 ecryptfs_printk(KERN_WARNING, "Error encrypting "
 190                                 "page (upper index [0x%.16x])\n", page->index);
 191                 ClearPageUptodate(page);
 192                 goto out;
 193         }
 194         SetPageUptodate(page);
 195         unlock_page(page);
 196 out:
 197         return rc;
 198 }
 199
 200 /**
 201  * Reads the data from the lower file file at index lower_page_index
 202  * and copies that data into page.
 203  *
 204  * @param page  Page to fill
 205  * @param lower_page_index Index of the page in the lower file to get
 206  */
 207 int ecryptfs_do_readpage(struct file *file, struct page *page,
 208                          pgoff_t lower_page_index)
 209 {
 210         int rc;
 211         struct dentry *dentry;
 212         struct file *lower_file;
 213         struct dentry *lower_dentry;
 214         struct inode *inode;
 215         struct inode *lower_inode;
 216         char *page_data;
 217         struct page *lower_page = NULL;
 218         char *lower_page_data;
 219         const struct address_space_operations *lower_a_ops;
 220
 221         dentry = file->f_path.dentry;
 222         lower_file = ecryptfs_file_to_lower(file);
 223         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 224         inode = dentry->d_inode;
 225         lower_inode = ecryptfs_inode_to_lower(inode);
 226         lower_a_ops = lower_inode->i_mapping->a_ops;
 227         lower_page = read_cache_page(lower_inode->i_mapping, lower_page_index,
 228                                      (filler_t *)lower_a_ops->readpage,
 229                                      (void *)lower_file);
 230         if (IS_ERR(lower_page)) {
 231                 rc = PTR_ERR(lower_page);
 232                 lower_page = NULL;
 233                 ecryptfs_printk(KERN_ERR, "Error reading from page cache\n");
 234                 goto out;
 235         }
 236         wait_on_page_locked(lower_page);
 237         page_data = (char *)kmap(page);
 238         if (!page_data) {
 239                 rc = -ENOMEM;
 240                 ecryptfs_printk(KERN_ERR, "Error mapping page\n");
 241                 goto out;
 242         }
 243         lower_page_data = (char *)kmap(lower_page);
 244         if (!lower_page_data) {
 245                 rc = -ENOMEM;
 246                 ecryptfs_printk(KERN_ERR, "Error mapping page\n");
 247                 kunmap(page);
 248                 goto out;
 249         }
 250         memcpy(page_data, lower_page_data, PAGE_CACHE_SIZE);
 251         kunmap(lower_page);
 252         kunmap(page);
 253         rc = 0;
 254 out:
 255         if (likely(lower_page))
 256                 page_cache_release(lower_page);
 257         if (rc == 0)
 258                 SetPageUptodate(page);
 259         else
 260                 ClearPageUptodate(page);
 261         return rc;
 262 }
 263
 264 /**
 265  * ecryptfs_readpage
 266  * @file: This is an ecryptfs file
 267  * @page: ecryptfs associated page to stick the read data into
 268  *
 269  * Read in a page, decrypting if necessary.
 270  *
 271  * Returns zero on success; non-zero on error.
 272  */
 273 static int ecryptfs_readpage(struct file *file, struct page *page)
 274 {
 275         int rc = 0;
 276         struct ecryptfs_crypt_stat *crypt_stat;
 277
 278         BUG_ON(!(file && file->f_path.dentry && file->f_path.dentry->d_inode));
 279         crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)
 280                         ->crypt_stat;
 281         if (!crypt_stat
 282             || !ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)
 283             || ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE)) {
 284                 ecryptfs_printk(KERN_DEBUG,
 285                                 "Passing through unencrypted page\n");
 286                 rc = ecryptfs_do_readpage(file, page, page->index);
 287                 if (rc) {
 288                         ecryptfs_printk(KERN_ERR, "Error reading page; rc = "
 289                                         "[%d]\n", rc);
 290                         goto out;
 291                 }
 292         } else {
 293                 rc = ecryptfs_decrypt_page(file, page);
 294                 if (rc) {
 295
 296                         ecryptfs_printk(KERN_ERR, "Error decrypting page; "
 297                                         "rc = [%d]\n", rc);
 298                         goto out;
 299                 }
 300         }
 301         SetPageUptodate(page);
 302 out:
 303         if (rc)
 304                 ClearPageUptodate(page);
 305         ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
 306                         page->index);
 307         unlock_page(page);
 308         return rc;
 309 }
 310
 311 static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
 312 {
 313         struct inode *inode = page->mapping->host;
 314         int end_byte_in_page;
 315         int rc = 0;
 316         char *page_virt;
 317
 318         if ((i_size_read(inode) / PAGE_CACHE_SIZE) == page->index) {
 319                 end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
 320                 if (to > end_byte_in_page)
 321                         end_byte_in_page = to;
 322                 page_virt = kmap(page);
 323                 if (!page_virt) {
 324                         rc = -ENOMEM;
 325                         ecryptfs_printk(KERN_WARNING,
 326                                         "Could not map page\n");
 327                         goto out;
 328                 }
 329                 memset((page_virt + end_byte_in_page), 0,
 330                        (PAGE_CACHE_SIZE - end_byte_in_page));
 331                 kunmap(page);
 332         }
 333 out:
 334         return rc;
 335 }
 336
 337 static int ecryptfs_prepare_write(struct file *file, struct page *page,
 338                                   unsigned from, unsigned to)
 339 {
 340         int rc = 0;
 341
 342         kmap(page);
 343         if (from == 0 && to == PAGE_CACHE_SIZE)
 344                 goto out;       /* If we are writing a full page, it will be
 345                                    up to date. */
 346         if (!PageUptodate(page))
 347                 rc = ecryptfs_do_readpage(file, page, page->index);
 348 out:
 349         return rc;
 350 }
 351
 352 int ecryptfs_grab_and_map_lower_page(struct page **lower_page,
 353                                      char **lower_virt,
 354                                      struct inode *lower_inode,
 355                                      unsigned long lower_page_index)
 356 {
 357         int rc = 0;
 358
 359         (*lower_page) = grab_cache_page(lower_inode->i_mapping,
 360                                         lower_page_index);
 361         if (!(*lower_page)) {
 362                 ecryptfs_printk(KERN_ERR, "grab_cache_page for "
 363                                 "lower_page_index = [0x%.16x] failed\n",
 364                                 lower_page_index);
 365                 rc = -EINVAL;
 366                 goto out;
 367         }
 368         if (lower_virt)
 369                 (*lower_virt) = kmap((*lower_page));
 370         else
 371                 kmap((*lower_page));
 372 out:
 373         return rc;
 374 }
 375
 376 int ecryptfs_writepage_and_release_lower_page(struct page *lower_page,
 377                                               struct inode *lower_inode,
 378                                               struct writeback_control *wbc)
 379 {
 380         int rc = 0;
 381
 382         rc = lower_inode->i_mapping->a_ops->writepage(lower_page, wbc);
 383         if (rc) {
 384                 ecryptfs_printk(KERN_ERR, "Error calling lower writepage(); "
 385                                 "rc = [%d]\n", rc);
 386                 goto out;
 387         }
 388         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 389         page_cache_release(lower_page);
 390 out:
 391         return rc;
 392 }
 393
 394 static void ecryptfs_unmap_and_release_lower_page(struct page *lower_page)
 395 {
 396         kunmap(lower_page);
 397         ecryptfs_printk(KERN_DEBUG, "Unlocking lower page with index = "
 398                         "[0x%.16x]\n", lower_page->index);
 399         unlock_page(lower_page);
 400         page_cache_release(lower_page);
 401 }
 402
 403 /**
 404  * ecryptfs_write_inode_size_to_header
 405  *
 406  * Writes the lower file size to the first 8 bytes of the header.
 407  *
 408  * Returns zero on success; non-zero on error.
 409  */
 410 int
 411 ecryptfs_write_inode_size_to_header(struct file *lower_file,
 412                                     struct inode *lower_inode,
 413                                     struct inode *inode)
 414 {
 415         int rc = 0;
 416         struct page *header_page;
 417         char *header_virt;
 418         const struct address_space_operations *lower_a_ops;
 419         u64 file_size;
 420
 421         rc = ecryptfs_grab_and_map_lower_page(&header_page, &header_virt,
 422                                               lower_inode, 0);
 423         if (rc) {
 424                 ecryptfs_printk(KERN_ERR, "grab_cache_page for header page "
 425                                 "failed\n");
 426                 goto out;
 427         }
 428         lower_a_ops = lower_inode->i_mapping->a_ops;
 429         rc = lower_a_ops->prepare_write(lower_file, header_page, 0, 8);
 430         file_size = (u64)i_size_read(inode);
 431         ecryptfs_printk(KERN_DEBUG, "Writing size: [0x%.16x]\n", file_size);
 432         file_size = cpu_to_be64(file_size);
 433         memcpy(header_virt, &file_size, sizeof(u64));
 434         rc = lower_a_ops->commit_write(lower_file, header_page, 0, 8);
 435         if (rc < 0)
 436                 ecryptfs_printk(KERN_ERR, "Error commiting header page "
 437                                 "write\n");
 438         ecryptfs_unmap_and_release_lower_page(header_page);
 439         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 440         mark_inode_dirty_sync(inode);
 441 out:
 442         return rc;
 443 }
 444
 445 int ecryptfs_get_lower_page(struct page **lower_page, struct inode *lower_inode,
 446                             struct file *lower_file,
 447                             unsigned long lower_page_index, int byte_offset,
 448                             int region_bytes)
 449 {
 450         int rc = 0;
 451
 452         rc = ecryptfs_grab_and_map_lower_page(lower_page, NULL, lower_inode,
 453                                               lower_page_index);
 454         if (rc) {
 455                 ecryptfs_printk(KERN_ERR, "Error attempting to grab and map "
 456                                 "lower page with index [0x%.16x]\n",
 457                                 lower_page_index);
 458                 goto out;
 459         }
 460         rc = lower_inode->i_mapping->a_ops->prepare_write(lower_file,
 461                                                           (*lower_page),
 462                                                           byte_offset,
 463                                                           region_bytes);
 464         if (rc) {
 465                 ecryptfs_printk(KERN_ERR, "prepare_write for "
 466                                 "lower_page_index = [0x%.16x] failed; rc = "
 467                                 "[%d]\n", lower_page_index, rc);
 468         }
 469 out:
 470         if (rc && (*lower_page)) {
 471                 ecryptfs_unmap_and_release_lower_page(*lower_page);
 472                 (*lower_page) = NULL;
 473         }
 474         return rc;
 475 }
 476
 477 /**
 478  * ecryptfs_commit_lower_page
 479  *
 480  * Returns zero on success; non-zero on error
 481  */
 482 int
 483 ecryptfs_commit_lower_page(struct page *lower_page, struct inode *lower_inode,
 484                            struct file *lower_file, int byte_offset,
 485                            int region_size)
 486 {
 487         int rc = 0;
 488
 489         rc = lower_inode->i_mapping->a_ops->commit_write(
 490                 lower_file, lower_page, byte_offset, region_size);
 491         if (rc < 0) {
 492                 ecryptfs_printk(KERN_ERR,
 493                                 "Error committing write; rc = [%d]\n", rc);
 494         } else
 495                 rc = 0;
 496         ecryptfs_unmap_and_release_lower_page(lower_page);
 497         return rc;
 498 }
 499
 500 /**
 501  * ecryptfs_copy_page_to_lower
 502  *
 503  * Used for plaintext pass-through; no page index interpolation
 504  * required.
 505  */
 506 int ecryptfs_copy_page_to_lower(struct page *page, struct inode *lower_inode,
 507                                 struct file *lower_file)
 508 {
 509         int rc = 0;
 510         struct page *lower_page;
 511
 512         rc = ecryptfs_get_lower_page(&lower_page, lower_inode, lower_file,
 513                                      page->index, 0, PAGE_CACHE_SIZE);
 514         if (rc) {
 515                 ecryptfs_printk(KERN_ERR, "Error attempting to get page "
 516                                 "at index [0x%.16x]\n", page->index);
 517                 goto out;
 518         }
 519         /* TODO: aops */
 520         memcpy((char *)page_address(lower_page), page_address(page),
 521                PAGE_CACHE_SIZE);
 522         rc = ecryptfs_commit_lower_page(lower_page, lower_inode, lower_file,
 523                                         0, PAGE_CACHE_SIZE);
 524         if (rc)
 525                 ecryptfs_printk(KERN_ERR, "Error attempting to commit page "
 526                                 "at index [0x%.16x]\n", page->index);
 527 out:
 528         return rc;
 529 }
 530
 531 /**
 532  * ecryptfs_commit_write
 533  * @file: The eCryptfs file object
 534  * @page: The eCryptfs page
 535  * @from: Ignored (we rotate the page IV on each write)
 536  * @to: Ignored
 537  *
 538  * This is where we encrypt the data and pass the encrypted data to
 539  * the lower filesystem.  In OpenPGP-compatible mode, we operate on
 540  * entire underlying packets.
 541  */
 542 static int ecryptfs_commit_write(struct file *file, struct page *page,
 543                                  unsigned from, unsigned to)
 544 {
 545         struct ecryptfs_page_crypt_context ctx;
 546         loff_t pos;
 547         struct inode *inode;
 548         struct inode *lower_inode;
 549         struct file *lower_file;
 550         struct ecryptfs_crypt_stat *crypt_stat;
 551         int rc;
 552
 553         inode = page->mapping->host;
 554         lower_inode = ecryptfs_inode_to_lower(inode);
 555         lower_file = ecryptfs_file_to_lower(file);
 556         mutex_lock(&lower_inode->i_mutex);
 557         crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)
 558                                 ->crypt_stat;
 559         if (ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE)) {
 560                 ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in "
 561                         "crypt_stat at memory location [%p]\n", crypt_stat);
 562                 ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE);
 563         } else
 564                 ecryptfs_printk(KERN_DEBUG, "Not a new file\n");
 565         ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
 566                         "(page w/ index = [0x%.16x], to = [%d])\n", page->index,
 567                         to);
 568         rc = fill_zeros_to_end_of_page(page, to);
 569         if (rc) {
 570                 ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
 571                                 "zeros in page with index = [0x%.16x]\n",
 572                                 page->index);
 573                 goto out;
 574         }
 575         ctx.page = page;
 576         ctx.mode = ECRYPTFS_PREPARE_COMMIT_MODE;
 577         ctx.param.lower_file = lower_file;
 578         rc = ecryptfs_encrypt_page(&ctx);
 579         if (rc) {
 580                 ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
 581                                 "index [0x%.16x])\n", page->index);
 582                 goto out;
 583         }
 584         rc = 0;
 585         inode->i_blocks = lower_inode->i_blocks;
 586         pos = (page->index << PAGE_CACHE_SHIFT) + to;
 587         if (pos > i_size_read(inode)) {
 588                 i_size_write(inode, pos);
 589                 ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
 590                                 "[0x%.16x]\n", i_size_read(inode));
 591         }
 592         ecryptfs_write_inode_size_to_header(lower_file, lower_inode, inode);
 593         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 594         mark_inode_dirty_sync(inode);
 595 out:
 596         kunmap(page); /* mapped in prior call (prepare_write) */
 597         if (rc < 0)
 598                 ClearPageUptodate(page);
 599         else
 600                 SetPageUptodate(page);
 601         mutex_unlock(&lower_inode->i_mutex);
 602         return rc;
 603 }
 604
 605 /**
 606  * write_zeros
 607  * @file: The ecryptfs file
 608  * @index: The index in which we are writing
 609  * @start: The position after the last block of data
 610  * @num_zeros: The number of zeros to write
 611  *
 612  * Write a specified number of zero's to a page.
 613  *
 614  * (start + num_zeros) must be less than or equal to PAGE_CACHE_SIZE
 615  */
 616 static
 617 int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros)
 618 {
 619         int rc = 0;
 620         struct page *tmp_page;
 621
 622         tmp_page = ecryptfs_get1page(file, index);
 623         if (IS_ERR(tmp_page)) {
 624                 ecryptfs_printk(KERN_ERR, "Error getting page at index "
 625                                 "[0x%.16x]\n", index);
 626                 rc = PTR_ERR(tmp_page);
 627                 goto out;
 628         }
 629         kmap(tmp_page);
 630         rc = ecryptfs_prepare_write(file, tmp_page, start, start + num_zeros);
 631         if (rc) {
 632                 ecryptfs_printk(KERN_ERR, "Error preparing to write zero's "
 633                                 "to remainder of page at index [0x%.16x]\n",
 634                                 index);
 635                 kunmap(tmp_page);
 636                 page_cache_release(tmp_page);
 637                 goto out;
 638         }
 639         memset(((char *)page_address(tmp_page) + start), 0, num_zeros);
 640         rc = ecryptfs_commit_write(file, tmp_page, start, start + num_zeros);
 641         if (rc < 0) {
 642                 ecryptfs_printk(KERN_ERR, "Error attempting to write zero's "
 643                                 "to remainder of page at index [0x%.16x]\n",
 644                                 index);
 645                 kunmap(tmp_page);
 646                 page_cache_release(tmp_page);
 647                 goto out;
 648         }
 649         rc = 0;
 650         kunmap(tmp_page);
 651         page_cache_release(tmp_page);
 652 out:
 653         return rc;
 654 }
 655
 656 static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
 657 {
 658         int rc = 0;
 659         struct inode *inode;
 660         struct inode *lower_inode;
 661
 662         inode = (struct inode *)mapping->host;
 663         lower_inode = ecryptfs_inode_to_lower(inode);
 664         if (lower_inode->i_mapping->a_ops->bmap)
 665                 rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
 666                                                          block);
 667         return rc;
 668 }
 669
 670 static void ecryptfs_sync_page(struct page *page)
 671 {
 672         struct inode *inode;
 673         struct inode *lower_inode;
 674         struct page *lower_page;
 675
 676         inode = page->mapping->host;
 677         lower_inode = ecryptfs_inode_to_lower(inode);
 678         /* NOTE: Recently swapped with grab_cache_page(), since
 679          * sync_page() just makes sure that pending I/O gets done. */
 680         lower_page = find_lock_page(lower_inode->i_mapping, page->index);
 681         if (!lower_page) {
 682                 ecryptfs_printk(KERN_DEBUG, "find_lock_page failed\n");
 683                 return;
 684         }
 685         lower_page->mapping->a_ops->sync_page(lower_page);
 686         ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
 687                         lower_page->index);
 688         unlock_page(lower_page);
 689         page_cache_release(lower_page);
 690 }
 691
 692 struct address_space_operations ecryptfs_aops = {
 693         .writepage = ecryptfs_writepage,
 694         .readpage = ecryptfs_readpage,
 695         .prepare_write = ecryptfs_prepare_write,
 696         .commit_write = ecryptfs_commit_write,
 697         .bmap = ecryptfs_bmap,
 698         .sync_page = ecryptfs_sync_page,
 699 };