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 key *key;
  72         int ret;
  73
  74         _enter("{%x:%u},", vnode->fid.vid, vnode->fid.vnode);
  75
  76         key = afs_request_key(vnode->volume->cell);
  77         if (IS_ERR(key)) {
  78                 _leave(" = %ld [key]", PTR_ERR(key));
  79                 return PTR_ERR(key);
  80         }
  81
  82         ret = afs_validate(vnode, key);
  83         if (ret < 0) {
  84                 _leave(" = %d [val]", ret);
  85                 return ret;
  86         }
  87
  88         file->private_data = key;
  89         _leave(" = 0");
  90         return 0;
  91 }
  92
  93 /*
  94  * release an AFS file or directory and discard its key
  95  */
  96 int afs_release(struct inode *inode, struct file *file)
  97 {
  98         struct afs_vnode *vnode = AFS_FS_I(inode);
  99
 100         _enter("{%x:%u},", vnode->fid.vid, vnode->fid.vnode);
 101
 102         key_put(file->private_data);
 103         _leave(" = 0");
 104         return 0;
 105 }
 106
 107 /*
 108  * Dispose of a ref to a read record.
 109  */
 110 void afs_put_read(struct afs_read *req)
 111 {
 112         int i;
 113
 114         if (atomic_dec_and_test(&req->usage)) {
 115                 for (i = 0; i < req->nr_pages; i++)
 116                         if (req->pages[i])
 117                                 put_page(req->pages[i]);
 118                 kfree(req);
 119         }
 120 }
 121
 122 #ifdef CONFIG_AFS_FSCACHE
 123 /*
 124  * deal with notification that a page was read from the cache
 125  */
 126 static void afs_file_readpage_read_complete(struct page *page,
 127                                             void *data,
 128                                             int error)
 129 {
 130         _enter("%p,%p,%d", page, data, error);
 131
 132         /* if the read completes with an error, we just unlock the page and let
 133          * the VM reissue the readpage */
 134         if (!error)
 135                 SetPageUptodate(page);
 136         unlock_page(page);
 137 }
 138 #endif
 139
 140 /*
 141  * read page from file, directory or symlink, given a key to use
 142  */
 143 int afs_page_filler(void *data, struct page *page)
 144 {
 145         struct inode *inode = page->mapping->host;
 146         struct afs_vnode *vnode = AFS_FS_I(inode);
 147         struct afs_read *req;
 148         struct key *key = data;
 149         int ret;
 150
 151         _enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
 152
 153         BUG_ON(!PageLocked(page));
 154
 155         ret = -ESTALE;
 156         if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
 157                 goto error;
 158
 159         /* is it cached? */
 160 #ifdef CONFIG_AFS_FSCACHE
 161         ret = fscache_read_or_alloc_page(vnode->cache,
 162                                          page,
 163                                          afs_file_readpage_read_complete,
 164                                          NULL,
 165                                          GFP_KERNEL);
 166 #else
 167         ret = -ENOBUFS;
 168 #endif
 169         switch (ret) {
 170                 /* read BIO submitted (page in cache) */
 171         case 0:
 172                 break;
 173
 174                 /* page not yet cached */
 175         case -ENODATA:
 176                 _debug("cache said ENODATA");
 177                 goto go_on;
 178
 179                 /* page will not be cached */
 180         case -ENOBUFS:
 181                 _debug("cache said ENOBUFS");
 182         default:
 183         go_on:
 184                 req = kzalloc(sizeof(struct afs_read) + sizeof(struct page *),
 185                               GFP_KERNEL);
 186                 if (!req)
 187                         goto enomem;
 188
 189                 /* We request a full page.  If the page is a partial one at the
 190                  * end of the file, the server will return a short read and the
 191                  * unmarshalling code will clear the unfilled space.
 192                  */
 193                 atomic_set(&req->usage, 1);
 194                 req->pos = (loff_t)page->index << PAGE_SHIFT;
 195                 req->len = PAGE_SIZE;
 196                 req->nr_pages = 1;
 197                 req->pages[0] = page;
 198                 get_page(page);
 199
 200                 /* read the contents of the file from the server into the
 201                  * page */
 202                 ret = afs_vnode_fetch_data(vnode, key, req);
 203                 afs_put_read(req);
 204                 if (ret < 0) {
 205                         if (ret == -ENOENT) {
 206                                 _debug("got NOENT from server"
 207                                        " - marking file deleted and stale");
 208                                 set_bit(AFS_VNODE_DELETED, &vnode->flags);
 209                                 ret = -ESTALE;
 210                         }
 211
 212 #ifdef CONFIG_AFS_FSCACHE
 213                         fscache_uncache_page(vnode->cache, page);
 214 #endif
 215                         BUG_ON(PageFsCache(page));
 216
 217                         if (ret == -EINTR ||
 218                             ret == -ENOMEM ||
 219                             ret == -ERESTARTSYS ||
 220                             ret == -EAGAIN)
 221                                 goto error;
 222                         goto io_error;
 223                 }
 224
 225                 SetPageUptodate(page);
 226
 227                 /* send the page to the cache */
 228 #ifdef CONFIG_AFS_FSCACHE
 229                 if (PageFsCache(page) &&
 230                     fscache_write_page(vnode->cache, page, GFP_KERNEL) != 0) {
 231                         fscache_uncache_page(vnode->cache, page);
 232                         BUG_ON(PageFsCache(page));
 233                 }
 234 #endif
 235                 unlock_page(page);
 236         }
 237
 238         _leave(" = 0");
 239         return 0;
 240
 241 io_error:
 242         SetPageError(page);
 243         goto error;
 244 enomem:
 245         ret = -ENOMEM;
 246 error:
 247         unlock_page(page);
 248         _leave(" = %d", ret);
 249         return ret;
 250 }
 251
 252 /*
 253  * read page from file, directory or symlink, given a file to nominate the key
 254  * to be used
 255  */
 256 static int afs_readpage(struct file *file, struct page *page)
 257 {
 258         struct key *key;
 259         int ret;
 260
 261         if (file) {
 262                 key = file->private_data;
 263                 ASSERT(key != NULL);
 264                 ret = afs_page_filler(key, page);
 265         } else {
 266                 struct inode *inode = page->mapping->host;
 267                 key = afs_request_key(AFS_FS_S(inode->i_sb)->volume->cell);
 268                 if (IS_ERR(key)) {
 269                         ret = PTR_ERR(key);
 270                 } else {
 271                         ret = afs_page_filler(key, page);
 272                         key_put(key);
 273                 }
 274         }
 275         return ret;
 276 }
 277
 278 /*
 279  * Make pages available as they're filled.
 280  */
 281 static void afs_readpages_page_done(struct afs_call *call, struct afs_read *req)
 282 {
 283 #ifdef CONFIG_AFS_FSCACHE
 284         struct afs_vnode *vnode = call->reply;
 285 #endif
 286         struct page *page = req->pages[req->index];
 287
 288         req->pages[req->index] = NULL;
 289         SetPageUptodate(page);
 290
 291         /* send the page to the cache */
 292 #ifdef CONFIG_AFS_FSCACHE
 293         if (PageFsCache(page) &&
 294             fscache_write_page(vnode->cache, page, GFP_KERNEL) != 0) {
 295                 fscache_uncache_page(vnode->cache, page);
 296                 BUG_ON(PageFsCache(page));
 297         }
 298 #endif
 299         unlock_page(page);
 300         put_page(page);
 301 }
 302
 303 /*
 304  * Read a contiguous set of pages.
 305  */
 306 static int afs_readpages_one(struct file *file, struct address_space *mapping,
 307                              struct list_head *pages)
 308 {
 309         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 310         struct afs_read *req;
 311         struct list_head *p;
 312         struct page *first, *page;
 313         struct key *key = file->private_data;
 314         pgoff_t index;
 315         int ret, n, i;
 316
 317         /* Count the number of contiguous pages at the front of the list.  Note
 318          * that the list goes prev-wards rather than next-wards.
 319          */
 320         first = list_entry(pages->prev, struct page, lru);
 321         index = first->index + 1;
 322         n = 1;
 323         for (p = first->lru.prev; p != pages; p = p->prev) {
 324                 page = list_entry(p, struct page, lru);
 325                 if (page->index != index)
 326                         break;
 327                 index++;
 328                 n++;
 329         }
 330
 331         req = kzalloc(sizeof(struct afs_read) + sizeof(struct page *) * n,
 332                       GFP_NOFS);
 333         if (!req)
 334                 return -ENOMEM;
 335
 336         atomic_set(&req->usage, 1);
 337         req->page_done = afs_readpages_page_done;
 338         req->pos = first->index;
 339         req->pos <<= PAGE_SHIFT;
 340
 341         /* Transfer the pages to the request.  We add them in until one fails
 342          * to add to the LRU and then we stop (as that'll make a hole in the
 343          * contiguous run.
 344          *
 345          * Note that it's possible for the file size to change whilst we're
 346          * doing this, but we rely on the server returning less than we asked
 347          * for if the file shrank.  We also rely on this to deal with a partial
 348          * page at the end of the file.
 349          */
 350         do {
 351                 page = list_entry(pages->prev, struct page, lru);
 352                 list_del(&page->lru);
 353                 index = page->index;
 354                 if (add_to_page_cache_lru(page, mapping, index,
 355                                           readahead_gfp_mask(mapping))) {
 356 #ifdef CONFIG_AFS_FSCACHE
 357                         fscache_uncache_page(vnode->cache, page);
 358 #endif
 359                         put_page(page);
 360                         break;
 361                 }
 362
 363                 req->pages[req->nr_pages++] = page;
 364                 req->len += PAGE_SIZE;
 365         } while (req->nr_pages < n);
 366
 367         if (req->nr_pages == 0) {
 368                 kfree(req);
 369                 return 0;
 370         }
 371
 372         ret = afs_vnode_fetch_data(vnode, key, req);
 373         if (ret < 0)
 374                 goto error;
 375
 376         task_io_account_read(PAGE_SIZE * req->nr_pages);
 377         afs_put_read(req);
 378         return 0;
 379
 380 error:
 381         if (ret == -ENOENT) {
 382                 _debug("got NOENT from server"
 383                        " - marking file deleted and stale");
 384                 set_bit(AFS_VNODE_DELETED, &vnode->flags);
 385                 ret = -ESTALE;
 386         }
 387
 388         for (i = 0; i < req->nr_pages; i++) {
 389                 page = req->pages[i];
 390                 if (page) {
 391 #ifdef CONFIG_AFS_FSCACHE
 392                         fscache_uncache_page(vnode->cache, page);
 393 #endif
 394                         SetPageError(page);
 395                         unlock_page(page);
 396                 }
 397         }
 398
 399         afs_put_read(req);
 400         return ret;
 401 }
 402
 403 /*
 404  * read a set of pages
 405  */
 406 static int afs_readpages(struct file *file, struct address_space *mapping,
 407                          struct list_head *pages, unsigned nr_pages)
 408 {
 409         struct key *key = file->private_data;
 410         struct afs_vnode *vnode;
 411         int ret = 0;
 412
 413         _enter("{%d},{%lu},,%d",
 414                key_serial(key), mapping->host->i_ino, nr_pages);
 415
 416         ASSERT(key != NULL);
 417
 418         vnode = AFS_FS_I(mapping->host);
 419         if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
 420                 _leave(" = -ESTALE");
 421                 return -ESTALE;
 422         }
 423
 424         /* attempt to read as many of the pages as possible */
 425 #ifdef CONFIG_AFS_FSCACHE
 426         ret = fscache_read_or_alloc_pages(vnode->cache,
 427                                           mapping,
 428                                           pages,
 429                                           &nr_pages,
 430                                           afs_file_readpage_read_complete,
 431                                           NULL,
 432                                           mapping_gfp_mask(mapping));
 433 #else
 434         ret = -ENOBUFS;
 435 #endif
 436
 437         switch (ret) {
 438                 /* all pages are being read from the cache */
 439         case 0:
 440                 BUG_ON(!list_empty(pages));
 441                 BUG_ON(nr_pages != 0);
 442                 _leave(" = 0 [reading all]");
 443                 return 0;
 444
 445                 /* there were pages that couldn't be read from the cache */
 446         case -ENODATA:
 447         case -ENOBUFS:
 448                 break;
 449
 450                 /* other error */
 451         default:
 452                 _leave(" = %d", ret);
 453                 return ret;
 454         }
 455
 456         while (!list_empty(pages)) {
 457                 ret = afs_readpages_one(file, mapping, pages);
 458                 if (ret < 0)
 459                         break;
 460         }
 461
 462         _leave(" = %d [netting]", ret);
 463         return ret;
 464 }
 465
 466 /*
 467  * write back a dirty page
 468  */
 469 static int afs_launder_page(struct page *page)
 470 {
 471         _enter("{%lu}", page->index);
 472
 473         return 0;
 474 }
 475
 476 /*
 477  * invalidate part or all of a page
 478  * - release a page and clean up its private data if offset is 0 (indicating
 479  *   the entire page)
 480  */
 481 static void afs_invalidatepage(struct page *page, unsigned int offset,
 482                                unsigned int length)
 483 {
 484         struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
 485
 486         _enter("{%lu},%u,%u", page->index, offset, length);
 487
 488         BUG_ON(!PageLocked(page));
 489
 490         /* we clean up only if the entire page is being invalidated */
 491         if (offset == 0 && length == PAGE_SIZE) {
 492 #ifdef CONFIG_AFS_FSCACHE
 493                 if (PageFsCache(page)) {
 494                         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 495                         fscache_wait_on_page_write(vnode->cache, page);
 496                         fscache_uncache_page(vnode->cache, page);
 497                 }
 498 #endif
 499
 500                 if (PagePrivate(page)) {
 501                         if (wb && !PageWriteback(page)) {
 502                                 set_page_private(page, 0);
 503                                 afs_put_writeback(wb);
 504                         }
 505
 506                         if (!page_private(page))
 507                                 ClearPagePrivate(page);
 508                 }
 509         }
 510
 511         _leave("");
 512 }
 513
 514 /*
 515  * release a page and clean up its private state if it's not busy
 516  * - return true if the page can now be released, false if not
 517  */
 518 static int afs_releasepage(struct page *page, gfp_t gfp_flags)
 519 {
 520         struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
 521         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 522
 523         _enter("{{%x:%u}[%lu],%lx},%x",
 524                vnode->fid.vid, vnode->fid.vnode, page->index, page->flags,
 525                gfp_flags);
 526
 527         /* deny if page is being written to the cache and the caller hasn't
 528          * elected to wait */
 529 #ifdef CONFIG_AFS_FSCACHE
 530         if (!fscache_maybe_release_page(vnode->cache, page, gfp_flags)) {
 531                 _leave(" = F [cache busy]");
 532                 return 0;
 533         }
 534 #endif
 535
 536         if (PagePrivate(page)) {
 537                 if (wb) {
 538                         set_page_private(page, 0);
 539                         afs_put_writeback(wb);
 540                 }
 541                 ClearPagePrivate(page);
 542         }
 543
 544         /* indicate that the page can be released */
 545         _leave(" = T");
 546         return 1;
 547 }