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 */
afs_open(struct inode * inode,struct file * file)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 */
afs_release(struct inode * inode,struct file * file)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 */
afs_file_readpage_read_complete(struct page * page,void * data,int error)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 */
afs_page_filler(void * data,struct page * page)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 */
afs_readpage(struct file * file,struct page * page)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 */
afs_readpages(struct file * file,struct address_space * mapping,struct list_head * pages,unsigned nr_pages)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 */
afs_launder_page(struct page * page)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 */
afs_invalidatepage(struct page * page,unsigned long offset)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 */
afs_releasepage(struct page * page,gfp_t gfp_flags)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