fs/afs/file.c

   1 /* file.c: AFS filesystem file handling
   2  *
   3  * Copyright (C) 2002 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/sched.h>
  16 #include <linux/slab.h>
  17 #include <linux/fs.h>
  18 #include <linux/pagemap.h>
  19 #include <linux/buffer_head.h>
  20 #include "volume.h"
  21 #include "vnode.h"
  22 #include <rxrpc/call.h>
  23 #include "internal.h"
  24
  25 #if 0
  26 static int afs_file_open(struct inode *inode, struct file *file);
  27 static int afs_file_release(struct inode *inode, struct file *file);
  28 #endif
  29
  30 static int afs_file_readpage(struct file *file, struct page *page);
  31 static int afs_file_invalidatepage(struct page *page, unsigned long offset);
  32 static int afs_file_releasepage(struct page *page, int gfp_flags);
  33
  34 static ssize_t afs_file_write(struct file *file, const char __user *buf,
  35                               size_t size, loff_t *off);
  36
  37 struct inode_operations afs_file_inode_operations = {
  38         .getattr        = afs_inode_getattr,
  39 };
  40
  41 struct file_operations afs_file_file_operations = {
  42         .read           = generic_file_read,
  43         .write          = afs_file_write,
  44         .mmap           = generic_file_mmap,
  45 #if 0
  46         .open           = afs_file_open,
  47         .release        = afs_file_release,
  48         .fsync          = afs_file_fsync,
  49 #endif
  50 };
  51
  52 struct address_space_operations afs_fs_aops = {
  53         .readpage       = afs_file_readpage,
  54         .sync_page      = block_sync_page,
  55         .set_page_dirty = __set_page_dirty_nobuffers,
  56         .releasepage    = afs_file_releasepage,
  57         .invalidatepage = afs_file_invalidatepage,
  58 };
  59
  60 /*****************************************************************************/
  61 /*
  62  * AFS file write
  63  */
  64 static ssize_t afs_file_write(struct file *file, const char __user *buf,
  65                               size_t size, loff_t *off)
  66 {
  67         struct afs_vnode *vnode;
  68
  69         vnode = AFS_FS_I(file->f_dentry->d_inode);
  70         if (vnode->flags & AFS_VNODE_DELETED)
  71                 return -ESTALE;
  72
  73         return -EIO;
  74 } /* end afs_file_write() */
  75
  76 /*****************************************************************************/
  77 /*
  78  * deal with notification that a page was read from the cache
  79  */
  80 #ifdef AFS_CACHING_SUPPORT
  81 static void afs_file_readpage_read_complete(void *cookie_data,
  82                                             struct page *page,
  83                                             void *data,
  84                                             int error)
  85 {
  86         _enter("%p,%p,%p,%d", cookie_data, page, data, error);
  87
  88         if (error)
  89                 SetPageError(page);
  90         else
  91                 SetPageUptodate(page);
  92         unlock_page(page);
  93
  94 } /* end afs_file_readpage_read_complete() */
  95 #endif
  96
  97 /*****************************************************************************/
  98 /*
  99  * deal with notification that a page was written to the cache
 100  */
 101 #ifdef AFS_CACHING_SUPPORT
 102 static void afs_file_readpage_write_complete(void *cookie_data,
 103                                              struct page *page,
 104                                              void *data,
 105                                              int error)
 106 {
 107         _enter("%p,%p,%p,%d", cookie_data, page, data, error);
 108
 109         unlock_page(page);
 110
 111 } /* end afs_file_readpage_write_complete() */
 112 #endif
 113
 114 /*****************************************************************************/
 115 /*
 116  * AFS read page from file (or symlink)
 117  */
 118 static int afs_file_readpage(struct file *file, struct page *page)
 119 {
 120         struct afs_rxfs_fetch_descriptor desc;
 121 #ifdef AFS_CACHING_SUPPORT
 122         struct cachefs_page *pageio;
 123 #endif
 124         struct afs_vnode *vnode;
 125         struct inode *inode;
 126         int ret;
 127
 128         inode = page->mapping->host;
 129
 130         _enter("{%lu},{%lu}", inode->i_ino, page->index);
 131
 132         vnode = AFS_FS_I(inode);
 133
 134         BUG_ON(!PageLocked(page));
 135
 136         ret = -ESTALE;
 137         if (vnode->flags & AFS_VNODE_DELETED)
 138                 goto error;
 139
 140 #ifdef AFS_CACHING_SUPPORT
 141         ret = cachefs_page_get_private(page, &pageio, GFP_NOIO);
 142         if (ret < 0)
 143                 goto error;
 144
 145         /* is it cached? */
 146         ret = cachefs_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
 155         switch (ret) {
 156                 /* read BIO submitted and wb-journal entry found */
 157         case 1:
 158                 BUG(); // TODO - handle wb-journal match
 159
 160                 /* read BIO submitted (page in cache) */
 161         case 0:
 162                 break;
 163
 164                 /* no page available in cache */
 165         case -ENOBUFS:
 166         case -ENODATA:
 167         default:
 168                 desc.fid        = vnode->fid;
 169                 desc.offset     = page->index << PAGE_CACHE_SHIFT;
 170                 desc.size       = min((size_t) (inode->i_size - desc.offset),
 171                                       (size_t) PAGE_SIZE);
 172                 desc.buffer     = kmap(page);
 173
 174                 clear_page(desc.buffer);
 175
 176                 /* read the contents of the file from the server into the
 177                  * page */
 178                 ret = afs_vnode_fetch_data(vnode, &desc);
 179                 kunmap(page);
 180                 if (ret < 0) {
 181                         if (ret==-ENOENT) {
 182                                 _debug("got NOENT from server"
 183                                        " - marking file deleted and stale");
 184                                 vnode->flags |= AFS_VNODE_DELETED;
 185                                 ret = -ESTALE;
 186                         }
 187
 188 #ifdef AFS_CACHING_SUPPORT
 189                         cachefs_uncache_page(vnode->cache, page);
 190 #endif
 191                         goto error;
 192                 }
 193
 194                 SetPageUptodate(page);
 195
 196 #ifdef AFS_CACHING_SUPPORT
 197                 if (cachefs_write_page(vnode->cache,
 198                                        page,
 199                                        afs_file_readpage_write_complete,
 200                                        NULL,
 201                                        GFP_KERNEL) != 0
 202                     ) {
 203                         cachefs_uncache_page(vnode->cache, page);
 204                         unlock_page(page);
 205                 }
 206 #else
 207                 unlock_page(page);
 208 #endif
 209         }
 210
 211         _leave(" = 0");
 212         return 0;
 213
 214  error:
 215         SetPageError(page);
 216         unlock_page(page);
 217
 218         _leave(" = %d", ret);
 219         return ret;
 220
 221 } /* end afs_file_readpage() */
 222
 223 /*****************************************************************************/
 224 /*
 225  * get a page cookie for the specified page
 226  */
 227 #ifdef AFS_CACHING_SUPPORT
 228 int afs_cache_get_page_cookie(struct page *page,
 229                               struct cachefs_page **_page_cookie)
 230 {
 231         int ret;
 232
 233         _enter("");
 234         ret = cachefs_page_get_private(page,_page_cookie, GFP_NOIO);
 235
 236         _leave(" = %d", ret);
 237         return ret;
 238 } /* end afs_cache_get_page_cookie() */
 239 #endif
 240
 241 /*****************************************************************************/
 242 /*
 243  * invalidate part or all of a page
 244  */
 245 static int afs_file_invalidatepage(struct page *page, unsigned long offset)
 246 {
 247         int ret = 1;
 248
 249         _enter("{%lu},%lu", page->index, offset);
 250
 251         BUG_ON(!PageLocked(page));
 252
 253         if (PagePrivate(page)) {
 254 #ifdef AFS_CACHING_SUPPORT
 255                 struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 256                 cachefs_uncache_page(vnode->cache,page);
 257 #endif
 258
 259                 /* We release buffers only if the entire page is being
 260                  * invalidated.
 261                  * The get_block cached value has been unconditionally
 262                  * invalidated, so real IO is not possible anymore.
 263                  */
 264                 if (offset == 0) {
 265                         BUG_ON(!PageLocked(page));
 266
 267                         ret = 0;
 268                         if (!PageWriteback(page))
 269                                 ret = page->mapping->a_ops->releasepage(page,
 270                                                                         0);
 271                 }
 272         }
 273
 274         _leave(" = %d", ret);
 275         return ret;
 276 } /* end afs_file_invalidatepage() */
 277
 278 /*****************************************************************************/
 279 /*
 280  * release a page and cleanup its private data
 281  */
 282 static int afs_file_releasepage(struct page *page, int gfp_flags)
 283 {
 284         struct cachefs_page *pageio;
 285
 286         _enter("{%lu},%x", page->index, gfp_flags);
 287
 288         if (PagePrivate(page)) {
 289 #ifdef AFS_CACHING_SUPPORT
 290                 struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 291                 cachefs_uncache_page(vnode->cache, page);
 292 #endif
 293
 294                 pageio = (struct cachefs_page *) page->private;
 295                 page->private = 0;
 296                 ClearPagePrivate(page);
 297
 298                 if (pageio)
 299                         kfree(pageio);
 300         }
 301
 302         _leave(" = 0");
 303         return 0;
 304 } /* end afs_file_releasepage() */