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           = do_sync_read,
  35         .write          = do_sync_write,
  36         .aio_read       = generic_file_aio_read,
  37         .aio_write      = 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 #ifdef CONFIG_AFS_FSCACHE
 107 /*
 108  * deal with notification that a page was read from the cache
 109  */
 110 static void afs_file_readpage_read_complete(struct page *page,
 111                                             void *data,
 112                                             int error)
 113 {
 114         _enter("%p,%p,%d", page, data, error);
 115
 116         /* if the read completes with an error, we just unlock the page and let
 117          * the VM reissue the readpage */
 118         if (!error)
 119                 SetPageUptodate(page);
 120         unlock_page(page);
 121 }
 122 #endif
 123
 124 /*
 125  * read page from file, directory or symlink, given a key to use
 126  */
 127 int afs_page_filler(void *data, struct page *page)
 128 {
 129         struct inode *inode = page->mapping->host;
 130         struct afs_vnode *vnode = AFS_FS_I(inode);
 131         struct key *key = data;
 132         size_t len;
 133         off_t offset;
 134         int ret;
 135
 136         _enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
 137
 138         BUG_ON(!PageLocked(page));
 139
 140         ret = -ESTALE;
 141         if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
 142                 goto error;
 143
 144         /* is it cached? */
 145 #ifdef CONFIG_AFS_FSCACHE
 146         ret = fscache_read_or_alloc_page(vnode->cache,
 147                                          page,
 148                                          afs_file_readpage_read_complete,
 149                                          NULL,
 150                                          GFP_KERNEL);
 151 #else
 152         ret = -ENOBUFS;
 153 #endif
 154         switch (ret) {
 155                 /* read BIO submitted (page in cache) */
 156         case 0:
 157                 break;
 158
 159                 /* page not yet cached */
 160         case -ENODATA:
 161                 _debug("cache said ENODATA");
 162                 goto go_on;
 163
 164                 /* page will not be cached */
 165         case -ENOBUFS:
 166                 _debug("cache said ENOBUFS");
 167         default:
 168         go_on:
 169                 offset = page->index << PAGE_CACHE_SHIFT;
 170                 len = min_t(size_t, i_size_read(inode) - offset, PAGE_SIZE);
 171
 172                 /* read the contents of the file from the server into the
 173                  * page */
 174                 ret = afs_vnode_fetch_data(vnode, key, offset, len, page);
 175                 if (ret < 0) {
 176                         if (ret == -ENOENT) {
 177                                 _debug("got NOENT from server"
 178                                        " - marking file deleted and stale");
 179                                 set_bit(AFS_VNODE_DELETED, &vnode->flags);
 180                                 ret = -ESTALE;
 181                         }
 182
 183 #ifdef CONFIG_AFS_FSCACHE
 184                         fscache_uncache_page(vnode->cache, page);
 185 #endif
 186                         BUG_ON(PageFsCache(page));
 187                         goto error;
 188                 }
 189
 190                 SetPageUptodate(page);
 191
 192                 /* send the page to the cache */
 193 #ifdef CONFIG_AFS_FSCACHE
 194                 if (PageFsCache(page) &&
 195                     fscache_write_page(vnode->cache, page, GFP_KERNEL) != 0) {
 196                         fscache_uncache_page(vnode->cache, page);
 197                         BUG_ON(PageFsCache(page));
 198                 }
 199 #endif
 200                 unlock_page(page);
 201         }
 202
 203         _leave(" = 0");
 204         return 0;
 205
 206 error:
 207         SetPageError(page);
 208         unlock_page(page);
 209         _leave(" = %d", ret);
 210         return ret;
 211 }
 212
 213 /*
 214  * read page from file, directory or symlink, given a file to nominate the key
 215  * to be used
 216  */
 217 static int afs_readpage(struct file *file, struct page *page)
 218 {
 219         struct key *key;
 220         int ret;
 221
 222         if (file) {
 223                 key = file->private_data;
 224                 ASSERT(key != NULL);
 225                 ret = afs_page_filler(key, page);
 226         } else {
 227                 struct inode *inode = page->mapping->host;
 228                 key = afs_request_key(AFS_FS_S(inode->i_sb)->volume->cell);
 229                 if (IS_ERR(key)) {
 230                         ret = PTR_ERR(key);
 231                 } else {
 232                         ret = afs_page_filler(key, page);
 233                         key_put(key);
 234                 }
 235         }
 236         return ret;
 237 }
 238
 239 /*
 240  * read a set of pages
 241  */
 242 static int afs_readpages(struct file *file, struct address_space *mapping,
 243                          struct list_head *pages, unsigned nr_pages)
 244 {
 245         struct key *key = file->private_data;
 246         struct afs_vnode *vnode;
 247         int ret = 0;
 248
 249         _enter("{%d},{%lu},,%d",
 250                key_serial(key), mapping->host->i_ino, nr_pages);
 251
 252         ASSERT(key != NULL);
 253
 254         vnode = AFS_FS_I(mapping->host);
 255         if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
 256                 _leave(" = -ESTALE");
 257                 return -ESTALE;
 258         }
 259
 260         /* attempt to read as many of the pages as possible */
 261 #ifdef CONFIG_AFS_FSCACHE
 262         ret = fscache_read_or_alloc_pages(vnode->cache,
 263                                           mapping,
 264                                           pages,
 265                                           &nr_pages,
 266                                           afs_file_readpage_read_complete,
 267                                           NULL,
 268                                           mapping_gfp_mask(mapping));
 269 #else
 270         ret = -ENOBUFS;
 271 #endif
 272
 273         switch (ret) {
 274                 /* all pages are being read from the cache */
 275         case 0:
 276                 BUG_ON(!list_empty(pages));
 277                 BUG_ON(nr_pages != 0);
 278                 _leave(" = 0 [reading all]");
 279                 return 0;
 280
 281                 /* there were pages that couldn't be read from the cache */
 282         case -ENODATA:
 283         case -ENOBUFS:
 284                 break;
 285
 286                 /* other error */
 287         default:
 288                 _leave(" = %d", ret);
 289                 return ret;
 290         }
 291
 292         /* load the missing pages from the network */
 293         ret = read_cache_pages(mapping, pages, afs_page_filler, key);
 294
 295         _leave(" = %d [netting]", ret);
 296         return ret;
 297 }
 298
 299 /*
 300  * write back a dirty page
 301  */
 302 static int afs_launder_page(struct page *page)
 303 {
 304         _enter("{%lu}", page->index);
 305
 306         return 0;
 307 }
 308
 309 /*
 310  * invalidate part or all of a page
 311  * - release a page and clean up its private data if offset is 0 (indicating
 312  *   the entire page)
 313  */
 314 static void afs_invalidatepage(struct page *page, unsigned int offset,
 315                                unsigned int length)
 316 {
 317         struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
 318
 319         _enter("{%lu},%u,%u", page->index, offset, length);
 320
 321         BUG_ON(!PageLocked(page));
 322
 323         /* we clean up only if the entire page is being invalidated */
 324         if (offset == 0 && length == PAGE_CACHE_SIZE) {
 325 #ifdef CONFIG_AFS_FSCACHE
 326                 if (PageFsCache(page)) {
 327                         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 328                         fscache_wait_on_page_write(vnode->cache, page);
 329                         fscache_uncache_page(vnode->cache, page);
 330                 }
 331 #endif
 332
 333                 if (PagePrivate(page)) {
 334                         if (wb && !PageWriteback(page)) {
 335                                 set_page_private(page, 0);
 336                                 afs_put_writeback(wb);
 337                         }
 338
 339                         if (!page_private(page))
 340                                 ClearPagePrivate(page);
 341                 }
 342         }
 343
 344         _leave("");
 345 }
 346
 347 /*
 348  * release a page and clean up its private state if it's not busy
 349  * - return true if the page can now be released, false if not
 350  */
 351 static int afs_releasepage(struct page *page, gfp_t gfp_flags)
 352 {
 353         struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
 354         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 355
 356         _enter("{{%x:%u}[%lu],%lx},%x",
 357                vnode->fid.vid, vnode->fid.vnode, page->index, page->flags,
 358                gfp_flags);
 359
 360         /* deny if page is being written to the cache and the caller hasn't
 361          * elected to wait */
 362 #ifdef CONFIG_AFS_FSCACHE
 363         if (!fscache_maybe_release_page(vnode->cache, page, gfp_flags)) {
 364                 _leave(" = F [cache busy]");
 365                 return 0;
 366         }
 367 #endif
 368
 369         if (PagePrivate(page)) {
 370                 if (wb) {
 371                         set_page_private(page, 0);
 372                         afs_put_writeback(wb);
 373                 }
 374                 ClearPagePrivate(page);
 375         }
 376
 377         /* indicate that the page can be released */
 378         _leave(" = T");
 379         return 1;
 380 }