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         if (!PageLocked(page))
 135                 PAGE_BUG(page);
 136
 137         ret = -ESTALE;
 138         if (vnode->flags & AFS_VNODE_DELETED)
 139                 goto error;
 140
 141 #ifdef AFS_CACHING_SUPPORT
 142         ret = cachefs_page_get_private(page, &pageio, GFP_NOIO);
 143         if (ret < 0)
 144                 goto error;
 145
 146         /* is it cached? */
 147         ret = cachefs_read_or_alloc_page(vnode->cache,
 148                                          page,
 149                                          afs_file_readpage_read_complete,
 150                                          NULL,
 151                                          GFP_KERNEL);
 152 #else
 153         ret = -ENOBUFS;
 154 #endif
 155
 156         switch (ret) {
 157                 /* read BIO submitted and wb-journal entry found */
 158         case 1:
 159                 BUG(); // TODO - handle wb-journal match
 160
 161                 /* read BIO submitted (page in cache) */
 162         case 0:
 163                 break;
 164
 165                 /* no page available in cache */
 166         case -ENOBUFS:
 167         case -ENODATA:
 168         default:
 169                 desc.fid        = vnode->fid;
 170                 desc.offset     = page->index << PAGE_CACHE_SHIFT;
 171                 desc.size       = min((size_t) (inode->i_size - desc.offset),
 172                                       (size_t) PAGE_SIZE);
 173                 desc.buffer     = kmap(page);
 174
 175                 clear_page(desc.buffer);
 176
 177                 /* read the contents of the file from the server into the
 178                  * page */
 179                 ret = afs_vnode_fetch_data(vnode, &desc);
 180                 kunmap(page);
 181                 if (ret < 0) {
 182                         if (ret==-ENOENT) {
 183                                 _debug("got NOENT from server"
 184                                        " - marking file deleted and stale");
 185                                 vnode->flags |= AFS_VNODE_DELETED;
 186                                 ret = -ESTALE;
 187                         }
 188
 189 #ifdef AFS_CACHING_SUPPORT
 190                         cachefs_uncache_page(vnode->cache, page);
 191 #endif
 192                         goto error;
 193                 }
 194
 195                 SetPageUptodate(page);
 196
 197 #ifdef AFS_CACHING_SUPPORT
 198                 if (cachefs_write_page(vnode->cache,
 199                                        page,
 200                                        afs_file_readpage_write_complete,
 201                                        NULL,
 202                                        GFP_KERNEL) != 0
 203                     ) {
 204                         cachefs_uncache_page(vnode->cache, page);
 205                         unlock_page(page);
 206                 }
 207 #else
 208                 unlock_page(page);
 209 #endif
 210         }
 211
 212         _leave(" = 0");
 213         return 0;
 214
 215  error:
 216         SetPageError(page);
 217         unlock_page(page);
 218
 219         _leave(" = %d", ret);
 220         return ret;
 221
 222 } /* end afs_file_readpage() */
 223
 224 /*****************************************************************************/
 225 /*
 226  * get a page cookie for the specified page
 227  */
 228 #ifdef AFS_CACHING_SUPPORT
 229 int afs_cache_get_page_cookie(struct page *page,
 230                               struct cachefs_page **_page_cookie)
 231 {
 232         int ret;
 233
 234         _enter("");
 235         ret = cachefs_page_get_private(page,_page_cookie, GFP_NOIO);
 236
 237         _leave(" = %d", ret);
 238         return ret;
 239 } /* end afs_cache_get_page_cookie() */
 240 #endif
 241
 242 /*****************************************************************************/
 243 /*
 244  * invalidate part or all of a page
 245  */
 246 static int afs_file_invalidatepage(struct page *page, unsigned long offset)
 247 {
 248         int ret = 1;
 249
 250         _enter("{%lu},%lu", page->index, offset);
 251
 252         BUG_ON(!PageLocked(page));
 253
 254         if (PagePrivate(page)) {
 255 #ifdef AFS_CACHING_SUPPORT
 256                 struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 257                 cachefs_uncache_page(vnode->cache,page);
 258 #endif
 259
 260                 /* We release buffers only if the entire page is being
 261                  * invalidated.
 262                  * The get_block cached value has been unconditionally
 263                  * invalidated, so real IO is not possible anymore.
 264                  */
 265                 if (offset == 0) {
 266                         BUG_ON(!PageLocked(page));
 267
 268                         ret = 0;
 269                         if (!PageWriteback(page))
 270                                 ret = page->mapping->a_ops->releasepage(page,
 271                                                                         0);
 272                 }
 273         }
 274
 275         _leave(" = %d", ret);
 276         return ret;
 277 } /* end afs_file_invalidatepage() */
 278
 279 /*****************************************************************************/
 280 /*
 281  * release a page and cleanup its private data
 282  */
 283 static int afs_file_releasepage(struct page *page, int gfp_flags)
 284 {
 285         struct cachefs_page *pageio;
 286
 287         _enter("{%lu},%x", page->index, gfp_flags);
 288
 289         if (PagePrivate(page)) {
 290 #ifdef AFS_CACHING_SUPPORT
 291                 struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
 292                 cachefs_uncache_page(vnode->cache, page);
 293 #endif
 294
 295                 pageio = (struct cachefs_page *) page->private;
 296                 page->private = 0;
 297                 ClearPagePrivate(page);
 298
 299                 if (pageio)
 300                         kfree(pageio);
 301         }
 302
 303         _leave(" = 0");
 304         return 0;
 305 } /* end afs_file_releasepage() */