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 };
  50
  51 const struct address_space_operations afs_fs_aops = {
  52         .readpage       = afs_readpage,
  53         .readpages      = afs_readpages,
  54         .set_page_dirty = afs_set_page_dirty,
  55         .launder_page   = afs_launder_page,
  56         .releasepage    = afs_releasepage,
  57         .invalidatepage = afs_invalidatepage,
  58         .write_begin    = afs_write_begin,
  59         .write_end      = afs_write_end,
  60         .writepage      = afs_writepage,
  61         .writepages     = afs_writepages,
  62 };
  63
  64 /*
  65  * open an AFS file or directory and attach a key to it
  66  */
  67 int afs_open(struct inode *inode, struct file *file)
  68 {
  69         struct afs_vnode *vnode = AFS_FS_I(inode);
  70         struct key *key;
  71         int ret;
  72
  73         _enter("{%x:%u},", vnode->fid.vid, vnode->fid.vnode);
  74
  75         key = afs_request_key(vnode->volume->cell);
  76         if (IS_ERR(key)) {
  77                 _leave(" = %ld [key]", PTR_ERR(key));
  78                 return PTR_ERR(key);
  79         }
  80
  81         ret = afs_validate(vnode, key);
  82         if (ret < 0) {
  83                 _leave(" = %d [val]", ret);
  84                 return ret;
  85         }
  86
  87         file->private_data = key;
  88         _leave(" = 0");
  89         return 0;
  90 }
  91
  92 /*
  93  * release an AFS file or directory and discard its key
  94  */
  95 int afs_release(struct inode *inode, struct file *file)
  96 {
  97         struct afs_vnode *vnode = AFS_FS_I(inode);
  98
  99         _enter("{%x:%u},", vnode->fid.vid, vnode->fid.vnode);
 100
 101         key_put(file->private_data);
 102         _leave(" = 0");
 103         return 0;
 104 }
 105
 106 /*
 107  * Dispose of a ref to a read record.
 108  */
 109 void afs_put_read(struct afs_read *req)
 110 {
 111         int i;
 112
 113         if (atomic_dec_and_test(&req->usage)) {
 114                 for (i = 0; i < req->nr_pages; i++)
 115                         if (req->pages[i])
 116                                 put_page(req->pages[i]);
 117                 kfree(req);
 118         }
 119 }
 120
 121 #ifdef CONFIG_AFS_FSCACHE
 122 /*
 123  * deal with notification that a page was read from the cache
 124  */
 125 static void afs_file_readpage_read_complete(struct page *page,
 126                                             void *data,
 127                                             int error)
 128 {
 129         _enter("%p,%p,%d", page, data, error);
 130
 131         /* if the read completes with an error, we just unlock the page and let
 132          * the VM reissue the readpage */
 133         if (!error)
 134                 SetPageUptodate(page);
 135         unlock_page(page);
 136 }
 137 #endif
 138
 139 /*
 140  * read page from file, directory or symlink, given a key to use
 141  */
 142 int afs_page_filler(void *data, struct page *page)
 143 {
 144         struct inode *inode = page->mapping->host;
 145         struct afs_vnode *vnode = AFS_FS_I(inode);
 146         struct afs_read *req;
 147         struct key *key = data;
 148         int ret;
 149
 150         _enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
 151
 152         BUG_ON(!PageLocked(page));
 153
 154         ret = -ESTALE;
 155         if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
 156                 goto error;
 157
 158         /* is it cached? */
 159 #ifdef CONFIG_AFS_FSCACHE
 160         ret = fscache_read_or_alloc_page(vnode->cache,
 161                                          page,
 162                                          afs_file_readpage_read_complete,
 163                                          NULL,
 164                                          GFP_KERNEL);
 165 #else
 166         ret = -ENOBUFS;
 167 #endif
 168         switch (ret) {
 169                 /* read BIO submitted (page in cache) */
 170         case 0:
 171                 break;
 172
 173                 /* page not yet cached */
 174         case -ENODATA:
 175                 _debug("cache said ENODATA");
 176                 goto go_on;
 177
 178                 /* page will not be cached */
 179         case -ENOBUFS:
 180                 _debug("cache said ENOBUFS");
 181         default:
 182         go_on:
 183                 req = kzalloc(sizeof(struct afs_read) + sizeof(struct page *),
 184                               GFP_KERNEL);
 185                 if (!req)
 186                         goto enomem;
 187
 188                 /* We request a full page.  If the page is a partial one at the
 189                  * end of the file, the server will return a short read and the
 190                  * unmarshalling code will clear the unfilled space.
 191                  */
 192                 atomic_set(&req->usage, 1);
 193                 req->pos = (loff_t)page->index << PAGE_SHIFT;
 194                 req->len = PAGE_SIZE;
 195                 req->nr_pages = 1;
 196                 req->pages[0] = page;
 197                 get_page(page);
 198
 199                 /* read the contents of the file from the server into the
 200                  * page */
 201                 ret = afs_vnode_fetch_data(vnode, key, req);
 202                 afs_put_read(req);
 203                 if (ret < 0) {
 204                         if (ret == -ENOENT) {
 205                                 _debug("got NOENT from server"
 206                                        " - marking file deleted and stale");
 207                                 set_bit(AFS_VNODE_DELETED, &vnode->flags);
 208                                 ret = -ESTALE;
 209                         }
 210
 211 #ifdef CONFIG_AFS_FSCACHE
 212                         fscache_uncache_page(vnode->cache, page);
 213 #endif
 214                         BUG_ON(PageFsCache(page));
 215
 216                         if (ret == -EINTR ||
 217                             ret == -ENOMEM ||
 218                             ret == -ERESTARTSYS ||
 219                             ret == -EAGAIN)
 220                                 goto error;
 221                         goto io_error;
 222                 }
 223
 224                 SetPageUptodate(page);
 225
 226                 /* send the page to the cache */
 227 #ifdef CONFIG_AFS_FSCACHE
 228                 if (PageFsCache(page) &&
 229                     fscache_write_page(vnode->cache, page, GFP_KERNEL) != 0) {
 230                         fscache_uncache_page(vnode->cache, page);
 231                         BUG_ON(PageFsCache(page));
 232                 }
 233 #endif
 234                 unlock_page(page);
 235         }
 236
 237         _leave(" = 0");
 238         return 0;
 239
 240 io_error:
 241         SetPageError(page);
 242         goto error;
 243 enomem:
 244         ret = -ENOMEM;
 245 error:
 246         unlock_page(page);
 247         _leave(" = %d", ret);
 248         return ret;
 249 }
 250
 251 /*
 252  * read page from file, directory or symlink, given a file to nominate the key
 253  * to be used
 254  */
 255 static int afs_readpage(struct file *file, struct page *page)
 256 {
 257         struct key *key;
 258         int ret;
 259
 260         if (file) {
 261                 key = file->private_data;
 262                 ASSERT(key != NULL);
 263                 ret = afs_page_filler(key, page);
 264         } else {
 265                 struct inode *inode = page->mapping->host;
 266                 key = afs_request_key(AFS_FS_S(inode->i_sb)->volume->cell);
 267                 if (IS_ERR(key)) {
 268                         ret = PTR_ERR(key);
 269                 } else {
 270                         ret = afs_page_filler(key, page);
 271                         key_put(key);
 272                 }
 273         }
 274         return ret;
 275 }
 276
 277 /*
 278  * Make pages available as they're filled.
 279  */
 280 static void afs_readpages_page_done(struct afs_call *call, struct afs_read *req)
 281 {
 282 #ifdef CONFIG_AFS_FSCACHE
 283         struct afs_vnode *vnode = call->reply;
 284 #endif
 285         struct page *page = req->pages[req->index];
 286
 287         req->pages[req->index] = NULL;
 288         SetPageUptodate(page);
 289
 290         /* send the page to the cache */
 291 #ifdef CONFIG_AFS_FSCACHE
 292         if (PageFsCache(page) &&
 293             fscache_write_page(vnode->cache, page, GFP_KERNEL) != 0) {
 294                 fscache_uncache_page(vnode->cache, page);
 295                 BUG_ON(PageFsCache(page));
 296         }
 297 #endif
 298         unlock_page(page);
 299         put_page(page);
 300 }
 301
 302 /*
 303  * Read a contiguous set of pages.
 304  */
 305 static int afs_readpages_one(struct file *file, struct address_space *mapping,
 306                              struct list_head *pages)
 307 {
 308         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 309         struct afs_read *req;
 310         struct list_head *p;
 311         struct page *first, *page;
 312         struct key *key = file->private_data;
 313         pgoff_t index;
 314         int ret, n, i;
 315
 316         /* Count the number of contiguous pages at the front of the list.  Note
 317          * that the list goes prev-wards rather than next-wards.
 318          */
 319         first = list_entry(pages->prev, struct page, lru);
 320         index = first->index + 1;
 321         n = 1;
 322         for (p = first->lru.prev; p != pages; p = p->prev) {
 323                 page = list_entry(p, struct page, lru);
 324                 if (page->index != index)
 325                         break;
 326                 index++;
 327                 n++;
 328         }
 329
 330         req = kzalloc(sizeof(struct afs_read) + sizeof(struct page *) * n,
 331                       GFP_NOFS);
 332         if (!req)
 333                 return -ENOMEM;
 334
 335         atomic_set(&req->usage, 1);
 336         req->page_done = afs_readpages_page_done;
 337         req->pos = first->index;
 338         req->pos <<= PAGE_SHIFT;
 339
 340         /* Transfer the pages to the request.  We add them in until one fails
 341          * to add to the LRU and then we stop (as that'll make a hole in the
 342          * contiguous run.
 343          *
 344          * Note that it's possible for the file size to change whilst we're
 345          * doing this, but we rely on the server returning less than we asked
 346          * for if the file shrank.  We also rely on this to deal with a partial
 347          * page at the end of the file.
 348          */
 349         do {
 350                 page = list_entry(pages->prev, struct page, lru);
 351                 list_del(&page->lru);
 352                 index = page->index;
 353                 if (add_to_page_cache_lru(page, mapping, index,
 354                                           readahead_gfp_mask(mapping))) {
 355 #ifdef CONFIG_AFS_FSCACHE
 356                         fscache_uncache_page(vnode->cache, page);
 357 #endif
 358                         put_page(page);
 359                         break;
 360                 }
 361
 362                 req->pages[req->nr_pages++] = page;
 363                 req->len += PAGE_SIZE;
 364         } while (req->nr_pages < n);
 365
 366         if (req->nr_pages == 0) {
 367                 kfree(req);
 368                 return 0;
 369         }
 370
 371         ret = afs_vnode_fetch_data(vnode, key, req);
 372         if (ret < 0)
 373                 goto error;
 374
 375         task_io_account_read(PAGE_SIZE * req->nr_pages);
 376         afs_put_read(req);
 377         return 0;
 378
 379 error:
 380         if (ret == -ENOENT) {
 381                 _debug("got NOENT from server"
 382                        " - marking file deleted and stale");
 383                 set_bit(AFS_VNODE_DELETED, &vnode->flags);
 384                 ret = -ESTALE;
 385         }
 386
 387         for (i = 0; i < req->nr_pages; i++) {
 388                 page = req->pages[i];
 389                 if (page) {
 390 #ifdef CONFIG_AFS_FSCACHE
 391                         fscache_uncache_page(vnode->cache, page);
 392 #endif
 393                         SetPageError(page);
 394                         unlock_page(page);
 395                 }
 396         }
 397
 398         afs_put_read(req);
 399         return ret;
 400 }
 401
 402 /*
 403  * read a set of pages
 404  */
 405 static int afs_readpages(struct file *file, struct address_space *mapping,
 406                          struct list_head *pages, unsigned nr_pages)
 407 {
 408         struct key *key = file->private_data;
 409         struct afs_vnode *vnode;
 410         int ret = 0;
 411
 412         _enter("{%d},{%lu},,%d",
 413                key_serial(key), mapping->host->i_ino, nr_pages);
 414
 415         ASSERT(key != NULL);
 416
 417         vnode = AFS_FS_I(mapping->host);
 418         if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
 419                 _leave(" = -ESTALE");
 420                 return -ESTALE;
 421         }
 422
 423         /* attempt to read as many of the pages as possible */
 424 #ifdef CONFIG_AFS_FSCACHE
 425         ret = fscache_read_or_alloc_pages(vnode->cache,
 426                                           mapping,
 427                                           pages,
 428                                           &nr_pages,
 429                                           afs_file_readpage_read_complete,
 430                                           NULL,
 431                                           mapping_gfp_mask(mapping));
 432 #else
 433         ret = -ENOBUFS;
 434 #endif
 435
 436         switch (ret) {
 437                 /* all pages are being read from the cache */
 438         case 0:
 439                 BUG_ON(!list_empty(pages));
 440                 BUG_ON(nr_pages != 0);
 441                 _leave(" = 0 [reading all]");
 442                 return 0;
 443
 444                 /* there were pages that couldn't be read from the cache */
 445         case -ENODATA:
 446         case -ENOBUFS:
 447                 break;
 448
 449                 /* other error */
 450         default:
 451                 _leave(" = %d", ret);
 452                 return ret;
 453         }
 454
 455         while (!list_empty(pages)) {
 456                 ret = afs_readpages_one(file, mapping, pages);
 457                 if (ret < 0)
 458                         break;
 459         }
 460
 461         _leave(" = %d [netting]", ret);
 462         return ret;
 463 }
 464
 465 /*
 466  * write back a dirty page
 467  */
 468 static int afs_launder_page(struct page *page)
 469 {
 470         _enter("{%lu}", page->index);
 471
 472         return 0;
 473 }
 474
 475 /*
 476  * invalidate part or all of a page
 477  * - release a page and clean up its private data if offset is 0 (indicating
 478  *   the entire page)
 479  */
 480 static void afs_invalidatepage(struct page *page, unsigned int offset,
 481                                unsigned int length)
 482 {
 483         struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
 484
 485         _enter("{%lu},%u,%u", page->index, offset, length);
 486
 487         BUG_ON(!PageLocked(page));
 488
 489         /* we clean up only if the entire page is being invalidated */
 490         if (offset == 0 && length == PAGE_SIZE) {
 491 #ifdef CONFIG_AFS_FSCACHE
 492                 if (PageFsCache(page)) {
 493                         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 494                         fscache_wait_on_page_write(vnode->cache, page);
 495                         fscache_uncache_page(vnode->cache, page);
 496                 }
 497 #endif
 498
 499                 if (PagePrivate(page)) {
 500                         if (wb && !PageWriteback(page)) {
 501                                 set_page_private(page, 0);
 502                                 afs_put_writeback(wb);
 503                         }
 504
 505                         if (!page_private(page))
 506                                 ClearPagePrivate(page);
 507                 }
 508         }
 509
 510         _leave("");
 511 }
 512
 513 /*
 514  * release a page and clean up its private state if it's not busy
 515  * - return true if the page can now be released, false if not
 516  */
 517 static int afs_releasepage(struct page *page, gfp_t gfp_flags)
 518 {
 519         struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
 520         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 521
 522         _enter("{{%x:%u}[%lu],%lx},%x",
 523                vnode->fid.vid, vnode->fid.vnode, page->index, page->flags,
 524                gfp_flags);
 525
 526         /* deny if page is being written to the cache and the caller hasn't
 527          * elected to wait */
 528 #ifdef CONFIG_AFS_FSCACHE
 529         if (!fscache_maybe_release_page(vnode->cache, page, gfp_flags)) {
 530                 _leave(" = F [cache busy]");
 531                 return 0;
 532         }
 533 #endif
 534
 535         if (PagePrivate(page)) {
 536                 if (wb) {
 537                         set_page_private(page, 0);
 538                         afs_put_writeback(wb);
 539                 }
 540                 ClearPagePrivate(page);
 541         }
 542
 543         /* indicate that the page can be released */
 544         _leave(" = T");
 545         return 1;
 546 }