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/slab.h>
  16 #include <linux/fs.h>
  17 #include <linux/pagemap.h>
  18 #include <linux/writeback.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 long offset);
  23 static int afs_releasepage(struct page *page, gfp_t gfp_flags);
  24 static int afs_launder_page(struct page *page);
  25
  26 static int afs_readpages(struct file *filp, struct address_space *mapping,
  27                          struct list_head *pages, unsigned nr_pages);
  28
  29 const struct file_operations afs_file_operations = {
  30         .open           = afs_open,
  31         .release        = afs_release,
  32         .llseek         = generic_file_llseek,
  33         .read           = do_sync_read,
  34         .write          = do_sync_write,
  35         .aio_read       = generic_file_aio_read,
  36         .aio_write      = 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 #ifdef CONFIG_AFS_FSCACHE
 106 /*
 107  * deal with notification that a page was read from the cache
 108  */
 109 static void afs_file_readpage_read_complete(struct page *page,
 110                                             void *data,
 111                                             int error)
 112 {
 113         _enter("%p,%p,%d", page, data, error);
 114
 115         /* if the read completes with an error, we just unlock the page and let
 116          * the VM reissue the readpage */
 117         if (!error)
 118                 SetPageUptodate(page);
 119         unlock_page(page);
 120 }
 121 #endif
 122
 123 /*
 124  * AFS read page from file, directory or symlink
 125  */
 126 static int afs_readpage(struct file *file, struct page *page)
 127 {
 128         struct afs_vnode *vnode;
 129         struct inode *inode;
 130         struct key *key;
 131         size_t len;
 132         off_t offset;
 133         int ret;
 134
 135         inode = page->mapping->host;
 136
 137         if (file) {
 138                 key = file->private_data;
 139                 ASSERT(key != NULL);
 140         } else {
 141                 key = afs_request_key(AFS_FS_S(inode->i_sb)->volume->cell);
 142                 if (IS_ERR(key)) {
 143                         ret = PTR_ERR(key);
 144                         goto error_nokey;
 145                 }
 146         }
 147
 148         _enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
 149
 150         vnode = AFS_FS_I(inode);
 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                 offset = page->index << PAGE_CACHE_SHIFT;
 184                 len = min_t(size_t, i_size_read(inode) - offset, PAGE_SIZE);
 185
 186                 /* read the contents of the file from the server into the
 187                  * page */
 188                 ret = afs_vnode_fetch_data(vnode, key, offset, len, page);
 189                 if (ret < 0) {
 190                         if (ret == -ENOENT) {
 191                                 _debug("got NOENT from server"
 192                                        " - marking file deleted and stale");
 193                                 set_bit(AFS_VNODE_DELETED, &vnode->flags);
 194                                 ret = -ESTALE;
 195                         }
 196
 197 #ifdef CONFIG_AFS_FSCACHE
 198                         fscache_uncache_page(vnode->cache, page);
 199 #endif
 200                         BUG_ON(PageFsCache(page));
 201                         goto error;
 202                 }
 203
 204                 SetPageUptodate(page);
 205
 206                 /* send the page to the cache */
 207 #ifdef CONFIG_AFS_FSCACHE
 208                 if (PageFsCache(page) &&
 209                     fscache_write_page(vnode->cache, page, GFP_KERNEL) != 0) {
 210                         fscache_uncache_page(vnode->cache, page);
 211                         BUG_ON(PageFsCache(page));
 212                 }
 213 #endif
 214                 unlock_page(page);
 215         }
 216
 217         if (!file)
 218                 key_put(key);
 219         _leave(" = 0");
 220         return 0;
 221
 222 error:
 223         SetPageError(page);
 224         unlock_page(page);
 225         if (!file)
 226                 key_put(key);
 227 error_nokey:
 228         _leave(" = %d", ret);
 229         return ret;
 230 }
 231
 232 /*
 233  * read a set of pages
 234  */
 235 static int afs_readpages(struct file *file, struct address_space *mapping,
 236                          struct list_head *pages, unsigned nr_pages)
 237 {
 238         struct afs_vnode *vnode;
 239         int ret = 0;
 240
 241         _enter(",{%lu},,%d", mapping->host->i_ino, nr_pages);
 242
 243         vnode = AFS_FS_I(mapping->host);
 244         if (vnode->flags & AFS_VNODE_DELETED) {
 245                 _leave(" = -ESTALE");
 246                 return -ESTALE;
 247         }
 248
 249         /* attempt to read as many of the pages as possible */
 250 #ifdef CONFIG_AFS_FSCACHE
 251         ret = fscache_read_or_alloc_pages(vnode->cache,
 252                                           mapping,
 253                                           pages,
 254                                           &nr_pages,
 255                                           afs_file_readpage_read_complete,
 256                                           NULL,
 257                                           mapping_gfp_mask(mapping));
 258 #else
 259         ret = -ENOBUFS;
 260 #endif
 261
 262         switch (ret) {
 263                 /* all pages are being read from the cache */
 264         case 0:
 265                 BUG_ON(!list_empty(pages));
 266                 BUG_ON(nr_pages != 0);
 267                 _leave(" = 0 [reading all]");
 268                 return 0;
 269
 270                 /* there were pages that couldn't be read from the cache */
 271         case -ENODATA:
 272         case -ENOBUFS:
 273                 break;
 274
 275                 /* other error */
 276         default:
 277                 _leave(" = %d", ret);
 278                 return ret;
 279         }
 280
 281         /* load the missing pages from the network */
 282         ret = read_cache_pages(mapping, pages, (void *) afs_readpage, file);
 283
 284         _leave(" = %d [netting]", ret);
 285         return ret;
 286 }
 287
 288 /*
 289  * write back a dirty page
 290  */
 291 static int afs_launder_page(struct page *page)
 292 {
 293         _enter("{%lu}", page->index);
 294
 295         return 0;
 296 }
 297
 298 /*
 299  * invalidate part or all of a page
 300  * - release a page and clean up its private data if offset is 0 (indicating
 301  *   the entire page)
 302  */
 303 static void afs_invalidatepage(struct page *page, unsigned long offset)
 304 {
 305         struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
 306
 307         _enter("{%lu},%lu", page->index, offset);
 308
 309         BUG_ON(!PageLocked(page));
 310
 311         /* we clean up only if the entire page is being invalidated */
 312         if (offset == 0) {
 313 #ifdef CONFIG_AFS_FSCACHE
 314                 if (PageFsCache(page)) {
 315                         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 316                         fscache_wait_on_page_write(vnode->cache, page);
 317                         fscache_uncache_page(vnode->cache, page);
 318                         ClearPageFsCache(page);
 319                 }
 320 #endif
 321
 322                 if (PagePrivate(page)) {
 323                         if (wb && !PageWriteback(page)) {
 324                                 set_page_private(page, 0);
 325                                 afs_put_writeback(wb);
 326                         }
 327
 328                         if (!page_private(page))
 329                                 ClearPagePrivate(page);
 330                 }
 331         }
 332
 333         _leave("");
 334 }
 335
 336 /*
 337  * release a page and clean up its private state if it's not busy
 338  * - return true if the page can now be released, false if not
 339  */
 340 static int afs_releasepage(struct page *page, gfp_t gfp_flags)
 341 {
 342         struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
 343         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 344
 345         _enter("{{%x:%u}[%lu],%lx},%x",
 346                vnode->fid.vid, vnode->fid.vnode, page->index, page->flags,
 347                gfp_flags);
 348
 349         /* deny if page is being written to the cache and the caller hasn't
 350          * elected to wait */
 351 #ifdef CONFIG_AFS_FSCACHE
 352         if (PageFsCache(page)) {
 353                 if (fscache_check_page_write(vnode->cache, page)) {
 354                         if (!(gfp_flags & __GFP_WAIT)) {
 355                                 _leave(" = F [cache busy]");
 356                                 return 0;
 357                         }
 358                         fscache_wait_on_page_write(vnode->cache, page);
 359                 }
 360
 361                 fscache_uncache_page(vnode->cache, page);
 362                 ClearPageFsCache(page);
 363         }
 364 #endif
 365
 366         if (PagePrivate(page)) {
 367                 if (wb) {
 368                         set_page_private(page, 0);
 369                         afs_put_writeback(wb);
 370                 }
 371                 ClearPagePrivate(page);
 372         }
 373
 374         /* indicate that the page can be released */
 375         _leave(" = T");
 376         return 1;
 377 }