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