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Linux/fs/afs/file.c

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  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/fs.h>
 16 #include <linux/pagemap.h>
 17 #include <linux/writeback.h>
 18 #include <linux/gfp.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 static int afs_readpages(struct file *filp, struct address_space *mapping,
 27                          struct list_head *pages, unsigned nr_pages);
 28 
 29 const struct file_operations afs_file_operations = {
 30         .open           = afs_open,
 31         .release        = afs_release,
 32         .llseek         = generic_file_llseek,
 33         .read           = do_sync_read,
 34         .write          = do_sync_write,
 35         .aio_read       = generic_file_aio_read,
 36         .aio_write      = afs_file_write,
 37         .mmap           = generic_file_readonly_mmap,
 38         .splice_read    = generic_file_splice_read,
 39         .fsync          = afs_fsync,
 40         .lock           = afs_lock,
 41         .flock          = afs_flock,
 42 };
 43 
 44 const struct inode_operations afs_file_inode_operations = {
 45         .getattr        = afs_getattr,
 46         .setattr        = afs_setattr,
 47         .permission     = afs_permission,
 48 };
 49 
 50 const struct address_space_operations afs_fs_aops = {
 51         .readpage       = afs_readpage,
 52         .readpages      = afs_readpages,
 53         .set_page_dirty = afs_set_page_dirty,
 54         .launder_page   = afs_launder_page,
 55         .releasepage    = afs_releasepage,
 56         .invalidatepage = afs_invalidatepage,
 57         .write_begin    = afs_write_begin,
 58         .write_end      = afs_write_end,
 59         .writepage      = afs_writepage,
 60         .writepages     = afs_writepages,
 61 };
 62 
 63 /*
 64  * open an AFS file or directory and attach a key to it
 65  */
 66 int afs_open(struct inode *inode, struct file *file)
 67 {
 68         struct afs_vnode *vnode = AFS_FS_I(inode);
 69         struct key *key;
 70         int ret;
 71 
 72         _enter("{%x:%u},", vnode->fid.vid, vnode->fid.vnode);
 73 
 74         key = afs_request_key(vnode->volume->cell);
 75         if (IS_ERR(key)) {
 76                 _leave(" = %ld [key]", PTR_ERR(key));
 77                 return PTR_ERR(key);
 78         }
 79 
 80         ret = afs_validate(vnode, key);
 81         if (ret < 0) {
 82                 _leave(" = %d [val]", ret);
 83                 return ret;
 84         }
 85 
 86         file->private_data = key;
 87         _leave(" = 0");
 88         return 0;
 89 }
 90 
 91 /*
 92  * release an AFS file or directory and discard its key
 93  */
 94 int afs_release(struct inode *inode, struct file *file)
 95 {
 96         struct afs_vnode *vnode = AFS_FS_I(inode);
 97 
 98         _enter("{%x:%u},", vnode->fid.vid, vnode->fid.vnode);
 99 
100         key_put(file->private_data);
101         _leave(" = 0");
102         return 0;
103 }
104 
105 #ifdef CONFIG_AFS_FSCACHE
106 /*
107  * deal with notification that a page was read from the cache
108  */
109 static void afs_file_readpage_read_complete(struct page *page,
110                                             void *data,
111                                             int error)
112 {
113         _enter("%p,%p,%d", page, data, error);
114 
115         /* if the read completes with an error, we just unlock the page and let
116          * the VM reissue the readpage */
117         if (!error)
118                 SetPageUptodate(page);
119         unlock_page(page);
120 }
121 #endif
122 
123 /*
124  * read page from file, directory or symlink, given a key to use
125  */
126 int afs_page_filler(void *data, struct page *page)
127 {
128         struct inode *inode = page->mapping->host;
129         struct afs_vnode *vnode = AFS_FS_I(inode);
130         struct key *key = data;
131         size_t len;
132         off_t offset;
133         int ret;
134 
135         _enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
136 
137         BUG_ON(!PageLocked(page));
138 
139         ret = -ESTALE;
140         if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
141                 goto error;
142 
143         /* is it cached? */
144 #ifdef CONFIG_AFS_FSCACHE
145         ret = fscache_read_or_alloc_page(vnode->cache,
146                                          page,
147                                          afs_file_readpage_read_complete,
148                                          NULL,
149                                          GFP_KERNEL);
150 #else
151         ret = -ENOBUFS;
152 #endif
153         switch (ret) {
154                 /* read BIO submitted (page in cache) */
155         case 0:
156                 break;
157 
158                 /* page not yet cached */
159         case -ENODATA:
160                 _debug("cache said ENODATA");
161                 goto go_on;
162 
163                 /* page will not be cached */
164         case -ENOBUFS:
165                 _debug("cache said ENOBUFS");
166         default:
167         go_on:
168                 offset = page->index << PAGE_CACHE_SHIFT;
169                 len = min_t(size_t, i_size_read(inode) - offset, PAGE_SIZE);
170 
171                 /* read the contents of the file from the server into the
172                  * page */
173                 ret = afs_vnode_fetch_data(vnode, key, offset, len, page);
174                 if (ret < 0) {
175                         if (ret == -ENOENT) {
176                                 _debug("got NOENT from server"
177                                        " - marking file deleted and stale");
178                                 set_bit(AFS_VNODE_DELETED, &vnode->flags);
179                                 ret = -ESTALE;
180                         }
181 
182 #ifdef CONFIG_AFS_FSCACHE
183                         fscache_uncache_page(vnode->cache, page);
184 #endif
185                         BUG_ON(PageFsCache(page));
186                         goto error;
187                 }
188 
189                 SetPageUptodate(page);
190 
191                 /* send the page to the cache */
192 #ifdef CONFIG_AFS_FSCACHE
193                 if (PageFsCache(page) &&
194                     fscache_write_page(vnode->cache, page, GFP_KERNEL) != 0) {
195                         fscache_uncache_page(vnode->cache, page);
196                         BUG_ON(PageFsCache(page));
197                 }
198 #endif
199                 unlock_page(page);
200         }
201 
202         _leave(" = 0");
203         return 0;
204 
205 error:
206         SetPageError(page);
207         unlock_page(page);
208         _leave(" = %d", ret);
209         return ret;
210 }
211 
212 /*
213  * read page from file, directory or symlink, given a file to nominate the key
214  * to be used
215  */
216 static int afs_readpage(struct file *file, struct page *page)
217 {
218         struct key *key;
219         int ret;
220 
221         if (file) {
222                 key = file->private_data;
223                 ASSERT(key != NULL);
224                 ret = afs_page_filler(key, page);
225         } else {
226                 struct inode *inode = page->mapping->host;
227                 key = afs_request_key(AFS_FS_S(inode->i_sb)->volume->cell);
228                 if (IS_ERR(key)) {
229                         ret = PTR_ERR(key);
230                 } else {
231                         ret = afs_page_filler(key, page);
232                         key_put(key);
233                 }
234         }
235         return ret;
236 }
237 
238 /*
239  * read a set of pages
240  */
241 static int afs_readpages(struct file *file, struct address_space *mapping,
242                          struct list_head *pages, unsigned nr_pages)
243 {
244         struct key *key = file->private_data;
245         struct afs_vnode *vnode;
246         int ret = 0;
247 
248         _enter("{%d},{%lu},,%d",
249                key_serial(key), mapping->host->i_ino, nr_pages);
250 
251         ASSERT(key != NULL);
252 
253         vnode = AFS_FS_I(mapping->host);
254         if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
255                 _leave(" = -ESTALE");
256                 return -ESTALE;
257         }
258 
259         /* attempt to read as many of the pages as possible */
260 #ifdef CONFIG_AFS_FSCACHE
261         ret = fscache_read_or_alloc_pages(vnode->cache,
262                                           mapping,
263                                           pages,
264                                           &nr_pages,
265                                           afs_file_readpage_read_complete,
266                                           NULL,
267                                           mapping_gfp_mask(mapping));
268 #else
269         ret = -ENOBUFS;
270 #endif
271 
272         switch (ret) {
273                 /* all pages are being read from the cache */
274         case 0:
275                 BUG_ON(!list_empty(pages));
276                 BUG_ON(nr_pages != 0);
277                 _leave(" = 0 [reading all]");
278                 return 0;
279 
280                 /* there were pages that couldn't be read from the cache */
281         case -ENODATA:
282         case -ENOBUFS:
283                 break;
284 
285                 /* other error */
286         default:
287                 _leave(" = %d", ret);
288                 return ret;
289         }
290 
291         /* load the missing pages from the network */
292         ret = read_cache_pages(mapping, pages, afs_page_filler, key);
293 
294         _leave(" = %d [netting]", ret);
295         return ret;
296 }
297 
298 /*
299  * write back a dirty page
300  */
301 static int afs_launder_page(struct page *page)
302 {
303         _enter("{%lu}", page->index);
304 
305         return 0;
306 }
307 
308 /*
309  * invalidate part or all of a page
310  * - release a page and clean up its private data if offset is 0 (indicating
311  *   the entire page)
312  */
313 static void afs_invalidatepage(struct page *page, unsigned long offset)
314 {
315         struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
316 
317         _enter("{%lu},%lu", page->index, offset);
318 
319         BUG_ON(!PageLocked(page));
320 
321         /* we clean up only if the entire page is being invalidated */
322         if (offset == 0) {
323 #ifdef CONFIG_AFS_FSCACHE
324                 if (PageFsCache(page)) {
325                         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
326                         fscache_wait_on_page_write(vnode->cache, page);
327                         fscache_uncache_page(vnode->cache, page);
328                 }
329 #endif
330 
331                 if (PagePrivate(page)) {
332                         if (wb && !PageWriteback(page)) {
333                                 set_page_private(page, 0);
334                                 afs_put_writeback(wb);
335                         }
336 
337                         if (!page_private(page))
338                                 ClearPagePrivate(page);
339                 }
340         }
341 
342         _leave("");
343 }
344 
345 /*
346  * release a page and clean up its private state if it's not busy
347  * - return true if the page can now be released, false if not
348  */
349 static int afs_releasepage(struct page *page, gfp_t gfp_flags)
350 {
351         struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
352         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
353 
354         _enter("{{%x:%u}[%lu],%lx},%x",
355                vnode->fid.vid, vnode->fid.vnode, page->index, page->flags,
356                gfp_flags);
357 
358         /* deny if page is being written to the cache and the caller hasn't
359          * elected to wait */
360 #ifdef CONFIG_AFS_FSCACHE
361         if (!fscache_maybe_release_page(vnode->cache, page, gfp_flags)) {
362                 _leave(" = F [cache busy]");
363                 return 0;
364         }
365 #endif
366 
367         if (PagePrivate(page)) {
368                 if (wb) {
369                         set_page_private(page, 0);
370                         afs_put_writeback(wb);
371                 }
372                 ClearPagePrivate(page);
373         }
374 
375         /* indicate that the page can be released */
376         _leave(" = T");
377         return 1;
378 }
379 

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