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