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 "internal.h"
  20
  21 static int afs_readpage(struct file *file, struct page *page);
  22 static void afs_invalidatepage(struct page *page, unsigned int offset,
  23                                unsigned int length);
  24 static int afs_releasepage(struct page *page, gfp_t gfp_flags);
  25 static int afs_launder_page(struct page *page);
  26
  27 static int afs_readpages(struct file *filp, struct address_space *mapping,
  28                          struct list_head *pages, unsigned nr_pages);
  29
  30 const struct file_operations afs_file_operations = {
  31         .open           = afs_open,
  32         .release        = afs_release,
  33         .llseek         = generic_file_llseek,
  34         .read_iter      = generic_file_read_iter,
  35         .write_iter     = afs_file_write,
  36         .mmap           = generic_file_readonly_mmap,
  37         .splice_read    = generic_file_splice_read,
  38         .fsync          = afs_fsync,
  39         .lock           = afs_lock,
  40         .flock          = afs_flock,
  41 };
  42
  43 const struct inode_operations afs_file_inode_operations = {
  44         .getattr        = afs_getattr,
  45         .setattr        = afs_setattr,
  46         .permission     = afs_permission,
  47 };
  48
  49 const struct address_space_operations afs_fs_aops = {
  50         .readpage       = afs_readpage,
  51         .readpages      = afs_readpages,
  52         .set_page_dirty = afs_set_page_dirty,
  53         .launder_page   = afs_launder_page,
  54         .releasepage    = afs_releasepage,
  55         .invalidatepage = afs_invalidatepage,
  56         .write_begin    = afs_write_begin,
  57         .write_end      = afs_write_end,
  58         .writepage      = afs_writepage,
  59         .writepages     = afs_writepages,
  60 };
  61
  62 /*
  63  * open an AFS file or directory and attach a key to it
  64  */
  65 int afs_open(struct inode *inode, struct file *file)
  66 {
  67         struct afs_vnode *vnode = AFS_FS_I(inode);
  68         struct key *key;
  69         int ret;
  70
  71         _enter("{%x:%u},", vnode->fid.vid, vnode->fid.vnode);
  72
  73         key = afs_request_key(vnode->volume->cell);
  74         if (IS_ERR(key)) {
  75                 _leave(" = %ld [key]", PTR_ERR(key));
  76                 return PTR_ERR(key);
  77         }
  78
  79         ret = afs_validate(vnode, key);
  80         if (ret < 0) {
  81                 _leave(" = %d [val]", ret);
  82                 return ret;
  83         }
  84
  85         file->private_data = key;
  86         _leave(" = 0");
  87         return 0;
  88 }
  89
  90 /*
  91  * release an AFS file or directory and discard its key
  92  */
  93 int afs_release(struct inode *inode, struct file *file)
  94 {
  95         struct afs_vnode *vnode = AFS_FS_I(inode);
  96
  97         _enter("{%x:%u},", vnode->fid.vid, vnode->fid.vnode);
  98
  99         key_put(file->private_data);
 100         _leave(" = 0");
 101         return 0;
 102 }
 103
 104 #ifdef CONFIG_AFS_FSCACHE
 105 /*
 106  * deal with notification that a page was read from the cache
 107  */
 108 static void afs_file_readpage_read_complete(struct page *page,
 109                                             void *data,
 110                                             int error)
 111 {
 112         _enter("%p,%p,%d", page, data, error);
 113
 114         /* if the read completes with an error, we just unlock the page and let
 115          * the VM reissue the readpage */
 116         if (!error)
 117                 SetPageUptodate(page);
 118         unlock_page(page);
 119 }
 120 #endif
 121
 122 /*
 123  * read page from file, directory or symlink, given a key to use
 124  */
 125 int afs_page_filler(void *data, struct page *page)
 126 {
 127         struct inode *inode = page->mapping->host;
 128         struct afs_vnode *vnode = AFS_FS_I(inode);
 129         struct key *key = data;
 130         size_t len;
 131         off_t offset;
 132         int ret;
 133
 134         _enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
 135
 136         BUG_ON(!PageLocked(page));
 137
 138         ret = -ESTALE;
 139         if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
 140                 goto error;
 141
 142         /* is it cached? */
 143 #ifdef CONFIG_AFS_FSCACHE
 144         ret = fscache_read_or_alloc_page(vnode->cache,
 145                                          page,
 146                                          afs_file_readpage_read_complete,
 147                                          NULL,
 148                                          GFP_KERNEL);
 149 #else
 150         ret = -ENOBUFS;
 151 #endif
 152         switch (ret) {
 153                 /* read BIO submitted (page in cache) */
 154         case 0:
 155                 break;
 156
 157                 /* page not yet cached */
 158         case -ENODATA:
 159                 _debug("cache said ENODATA");
 160                 goto go_on;
 161
 162                 /* page will not be cached */
 163         case -ENOBUFS:
 164                 _debug("cache said ENOBUFS");
 165         default:
 166         go_on:
 167                 offset = page->index << PAGE_SHIFT;
 168                 len = min_t(size_t, i_size_read(inode) - offset, PAGE_SIZE);
 169
 170                 /* read the contents of the file from the server into the
 171                  * page */
 172                 ret = afs_vnode_fetch_data(vnode, key, offset, len, page);
 173                 if (ret < 0) {
 174                         if (ret == -ENOENT) {
 175                                 _debug("got NOENT from server"
 176                                        " - marking file deleted and stale");
 177                                 set_bit(AFS_VNODE_DELETED, &vnode->flags);
 178                                 ret = -ESTALE;
 179                         }
 180
 181 #ifdef CONFIG_AFS_FSCACHE
 182                         fscache_uncache_page(vnode->cache, page);
 183 #endif
 184                         BUG_ON(PageFsCache(page));
 185                         goto error;
 186                 }
 187
 188                 SetPageUptodate(page);
 189
 190                 /* send the page to the cache */
 191 #ifdef CONFIG_AFS_FSCACHE
 192                 if (PageFsCache(page) &&
 193                     fscache_write_page(vnode->cache, page, GFP_KERNEL) != 0) {
 194                         fscache_uncache_page(vnode->cache, page);
 195                         BUG_ON(PageFsCache(page));
 196                 }
 197 #endif
 198                 unlock_page(page);
 199         }
 200
 201         _leave(" = 0");
 202         return 0;
 203
 204 error:
 205         SetPageError(page);
 206         unlock_page(page);
 207         _leave(" = %d", ret);
 208         return ret;
 209 }
 210
 211 /*
 212  * read page from file, directory or symlink, given a file to nominate the key
 213  * to be used
 214  */
 215 static int afs_readpage(struct file *file, struct page *page)
 216 {
 217         struct key *key;
 218         int ret;
 219
 220         if (file) {
 221                 key = file->private_data;
 222                 ASSERT(key != NULL);
 223                 ret = afs_page_filler(key, page);
 224         } else {
 225                 struct inode *inode = page->mapping->host;
 226                 key = afs_request_key(AFS_FS_S(inode->i_sb)->volume->cell);
 227                 if (IS_ERR(key)) {
 228                         ret = PTR_ERR(key);
 229                 } else {
 230                         ret = afs_page_filler(key, page);
 231                         key_put(key);
 232                 }
 233         }
 234         return ret;
 235 }
 236
 237 /*
 238  * read a set of pages
 239  */
 240 static int afs_readpages(struct file *file, struct address_space *mapping,
 241                          struct list_head *pages, unsigned nr_pages)
 242 {
 243         struct key *key = file->private_data;
 244         struct afs_vnode *vnode;
 245         int ret = 0;
 246
 247         _enter("{%d},{%lu},,%d",
 248                key_serial(key), mapping->host->i_ino, nr_pages);
 249
 250         ASSERT(key != NULL);
 251
 252         vnode = AFS_FS_I(mapping->host);
 253         if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
 254                 _leave(" = -ESTALE");
 255                 return -ESTALE;
 256         }
 257
 258         /* attempt to read as many of the pages as possible */
 259 #ifdef CONFIG_AFS_FSCACHE
 260         ret = fscache_read_or_alloc_pages(vnode->cache,
 261                                           mapping,
 262                                           pages,
 263                                           &nr_pages,
 264                                           afs_file_readpage_read_complete,
 265                                           NULL,
 266                                           mapping_gfp_mask(mapping));
 267 #else
 268         ret = -ENOBUFS;
 269 #endif
 270
 271         switch (ret) {
 272                 /* all pages are being read from the cache */
 273         case 0:
 274                 BUG_ON(!list_empty(pages));
 275                 BUG_ON(nr_pages != 0);
 276                 _leave(" = 0 [reading all]");
 277                 return 0;
 278
 279                 /* there were pages that couldn't be read from the cache */
 280         case -ENODATA:
 281         case -ENOBUFS:
 282                 break;
 283
 284                 /* other error */
 285         default:
 286                 _leave(" = %d", ret);
 287                 return ret;
 288         }
 289
 290         /* load the missing pages from the network */
 291         ret = read_cache_pages(mapping, pages, afs_page_filler, key);
 292
 293         _leave(" = %d [netting]", ret);
 294         return ret;
 295 }
 296
 297 /*
 298  * write back a dirty page
 299  */
 300 static int afs_launder_page(struct page *page)
 301 {
 302         _enter("{%lu}", page->index);
 303
 304         return 0;
 305 }
 306
 307 /*
 308  * invalidate part or all of a page
 309  * - release a page and clean up its private data if offset is 0 (indicating
 310  *   the entire page)
 311  */
 312 static void afs_invalidatepage(struct page *page, unsigned int offset,
 313                                unsigned int length)
 314 {
 315         struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
 316
 317         _enter("{%lu},%u,%u", page->index, offset, length);
 318
 319         BUG_ON(!PageLocked(page));
 320
 321         /* we clean up only if the entire page is being invalidated */
 322         if (offset == 0 && length == PAGE_SIZE) {
 323 #ifdef CONFIG_AFS_FSCACHE
 324                 if (PageFsCache(page)) {
 325                         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 326                         fscache_wait_on_page_write(vnode->cache, page);
 327                         fscache_uncache_page(vnode->cache, page);
 328                 }
 329 #endif
 330
 331                 if (PagePrivate(page)) {
 332                         if (wb && !PageWriteback(page)) {
 333                                 set_page_private(page, 0);
 334                                 afs_put_writeback(wb);
 335                         }
 336
 337                         if (!page_private(page))
 338                                 ClearPagePrivate(page);
 339                 }
 340         }
 341
 342         _leave("");
 343 }
 344
 345 /*
 346  * release a page and clean up its private state if it's not busy
 347  * - return true if the page can now be released, false if not
 348  */
 349 static int afs_releasepage(struct page *page, gfp_t gfp_flags)
 350 {
 351         struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
 352         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 353
 354         _enter("{{%x:%u}[%lu],%lx},%x",
 355                vnode->fid.vid, vnode->fid.vnode, page->index, page->flags,
 356                gfp_flags);
 357
 358         /* deny if page is being written to the cache and the caller hasn't
 359          * elected to wait */
 360 #ifdef CONFIG_AFS_FSCACHE
 361         if (!fscache_maybe_release_page(vnode->cache, page, gfp_flags)) {
 362                 _leave(" = F [cache busy]");
 363                 return 0;
 364         }
 365 #endif
 366
 367         if (PagePrivate(page)) {
 368                 if (wb) {
 369                         set_page_private(page, 0);
 370                         afs_put_writeback(wb);
 371                 }
 372                 ClearPagePrivate(page);
 373         }
 374
 375         /* indicate that the page can be released */
 376         _leave(" = T");
 377         return 1;
 378 }