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 const struct file_operations afs_file_operations = {
  27         .open           = afs_open,
  28         .release        = afs_release,
  29         .llseek         = generic_file_llseek,
  30         .read           = do_sync_read,
  31         .write          = do_sync_write,
  32         .aio_read       = generic_file_aio_read,
  33         .aio_write      = afs_file_write,
  34         .mmap           = generic_file_readonly_mmap,
  35         .sendfile       = generic_file_sendfile,
  36         .fsync          = afs_fsync,
  37 };
  38
  39 const struct inode_operations afs_file_inode_operations = {
  40         .getattr        = afs_getattr,
  41         .setattr        = afs_setattr,
  42         .permission     = afs_permission,
  43 };
  44
  45 const struct address_space_operations afs_fs_aops = {
  46         .readpage       = afs_readpage,
  47         .set_page_dirty = afs_set_page_dirty,
  48         .launder_page   = afs_launder_page,
  49         .releasepage    = afs_releasepage,
  50         .invalidatepage = afs_invalidatepage,
  51         .prepare_write  = afs_prepare_write,
  52         .commit_write   = afs_commit_write,
  53         .writepage      = afs_writepage,
  54         .writepages     = afs_writepages,
  55 };
  56
  57 /*
  58  * open an AFS file or directory and attach a key to it
  59  */
  60 int afs_open(struct inode *inode, struct file *file)
  61 {
  62         struct afs_vnode *vnode = AFS_FS_I(inode);
  63         struct key *key;
  64         int ret;
  65
  66         _enter("{%x:%u},", vnode->fid.vid, vnode->fid.vnode);
  67
  68         key = afs_request_key(vnode->volume->cell);
  69         if (IS_ERR(key)) {
  70                 _leave(" = %ld [key]", PTR_ERR(key));
  71                 return PTR_ERR(key);
  72         }
  73
  74         ret = afs_validate(vnode, key);
  75         if (ret < 0) {
  76                 _leave(" = %d [val]", ret);
  77                 return ret;
  78         }
  79
  80         file->private_data = key;
  81         _leave(" = 0");
  82         return 0;
  83 }
  84
  85 /*
  86  * release an AFS file or directory and discard its key
  87  */
  88 int afs_release(struct inode *inode, struct file *file)
  89 {
  90         struct afs_vnode *vnode = AFS_FS_I(inode);
  91
  92         _enter("{%x:%u},", vnode->fid.vid, vnode->fid.vnode);
  93
  94         key_put(file->private_data);
  95         _leave(" = 0");
  96         return 0;
  97 }
  98
  99 /*
 100  * deal with notification that a page was read from the cache
 101  */
 102 #ifdef AFS_CACHING_SUPPORT
 103 static void afs_readpage_read_complete(void *cookie_data,
 104                                        struct page *page,
 105                                        void *data,
 106                                        int error)
 107 {
 108         _enter("%p,%p,%p,%d", cookie_data, page, data, error);
 109
 110         if (error)
 111                 SetPageError(page);
 112         else
 113                 SetPageUptodate(page);
 114         unlock_page(page);
 115
 116 }
 117 #endif
 118
 119 /*
 120  * deal with notification that a page was written to the cache
 121  */
 122 #ifdef AFS_CACHING_SUPPORT
 123 static void afs_readpage_write_complete(void *cookie_data,
 124                                         struct page *page,
 125                                         void *data,
 126                                         int error)
 127 {
 128         _enter("%p,%p,%p,%d", cookie_data, page, data, error);
 129
 130         unlock_page(page);
 131 }
 132 #endif
 133
 134 /*
 135  * AFS read page from file, directory or symlink
 136  */
 137 static int afs_readpage(struct file *file, struct page *page)
 138 {
 139         struct afs_vnode *vnode;
 140         struct inode *inode;
 141         struct key *key;
 142         size_t len;
 143         off_t offset;
 144         int ret;
 145
 146         inode = page->mapping->host;
 147
 148         ASSERT(file != NULL);
 149         key = file->private_data;
 150         ASSERT(key != NULL);
 151
 152         _enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
 153
 154         vnode = AFS_FS_I(inode);
 155
 156         BUG_ON(!PageLocked(page));
 157
 158         ret = -ESTALE;
 159         if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
 160                 goto error;
 161
 162 #ifdef AFS_CACHING_SUPPORT
 163         /* is it cached? */
 164         ret = cachefs_read_or_alloc_page(vnode->cache,
 165                                          page,
 166                                          afs_file_readpage_read_complete,
 167                                          NULL,
 168                                          GFP_KERNEL);
 169 #else
 170         ret = -ENOBUFS;
 171 #endif
 172
 173         switch (ret) {
 174                 /* read BIO submitted and wb-journal entry found */
 175         case 1:
 176                 BUG(); // TODO - handle wb-journal match
 177
 178                 /* read BIO submitted (page in cache) */
 179         case 0:
 180                 break;
 181
 182                 /* no page available in cache */
 183         case -ENOBUFS:
 184         case -ENODATA:
 185         default:
 186                 offset = page->index << PAGE_CACHE_SHIFT;
 187                 len = min_t(size_t, i_size_read(inode) - offset, PAGE_SIZE);
 188
 189                 /* read the contents of the file from the server into the
 190                  * page */
 191                 ret = afs_vnode_fetch_data(vnode, key, offset, len, page);
 192                 if (ret < 0) {
 193                         if (ret == -ENOENT) {
 194                                 _debug("got NOENT from server"
 195                                        " - marking file deleted and stale");
 196                                 set_bit(AFS_VNODE_DELETED, &vnode->flags);
 197                                 ret = -ESTALE;
 198                         }
 199 #ifdef AFS_CACHING_SUPPORT
 200                         cachefs_uncache_page(vnode->cache, page);
 201 #endif
 202                         goto error;
 203                 }
 204
 205                 SetPageUptodate(page);
 206
 207 #ifdef AFS_CACHING_SUPPORT
 208                 if (cachefs_write_page(vnode->cache,
 209                                        page,
 210                                        afs_file_readpage_write_complete,
 211                                        NULL,
 212                                        GFP_KERNEL) != 0
 213                     ) {
 214                         cachefs_uncache_page(vnode->cache, page);
 215                         unlock_page(page);
 216                 }
 217 #else
 218                 unlock_page(page);
 219 #endif
 220         }
 221
 222         _leave(" = 0");
 223         return 0;
 224
 225 error:
 226         SetPageError(page);
 227         unlock_page(page);
 228         _leave(" = %d", ret);
 229         return ret;
 230 }
 231
 232 /*
 233  * invalidate part or all of a page
 234  */
 235 static void afs_invalidatepage(struct page *page, unsigned long offset)
 236 {
 237         int ret = 1;
 238
 239         _enter("{%lu},%lu", page->index, offset);
 240
 241         BUG_ON(!PageLocked(page));
 242
 243         if (PagePrivate(page)) {
 244                 /* We release buffers only if the entire page is being
 245                  * invalidated.
 246                  * The get_block cached value has been unconditionally
 247                  * invalidated, so real IO is not possible anymore.
 248                  */
 249                 if (offset == 0) {
 250                         BUG_ON(!PageLocked(page));
 251
 252                         ret = 0;
 253                         if (!PageWriteback(page))
 254                                 ret = page->mapping->a_ops->releasepage(page,
 255                                                                         0);
 256                         /* possibly should BUG_ON(!ret); - neilb */
 257                 }
 258         }
 259
 260         _leave(" = %d", ret);
 261 }
 262
 263 /*
 264  * write back a dirty page
 265  */
 266 static int afs_launder_page(struct page *page)
 267 {
 268         _enter("{%lu}", page->index);
 269
 270         return 0;
 271 }
 272
 273 /*
 274  * release a page and cleanup its private data
 275  */
 276 static int afs_releasepage(struct page *page, gfp_t gfp_flags)
 277 {
 278         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 279         struct afs_writeback *wb;
 280
 281         _enter("{{%x:%u}[%lu],%lx},%x",
 282                vnode->fid.vid, vnode->fid.vnode, page->index, page->flags,
 283                gfp_flags);
 284
 285         if (PagePrivate(page)) {
 286                 wb = (struct afs_writeback *) page_private(page);
 287                 ASSERT(wb != NULL);
 288                 set_page_private(page, 0);
 289                 ClearPagePrivate(page);
 290                 afs_put_writeback(wb);
 291         }
 292
 293         _leave(" = 0");
 294         return 0;
 295 }