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