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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/slab.h> |
16 | #include <linux/fs.h> |
17 | #include <linux/pagemap.h> |
18 | #include <linux/writeback.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 | * AFS read page from file, directory or symlink |
125 | */ |
126 | static int afs_readpage(struct file *file, struct page *page) |
127 | { |
128 | struct afs_vnode *vnode; |
129 | struct inode *inode; |
130 | struct key *key; |
131 | size_t len; |
132 | off_t offset; |
133 | int ret; |
134 | |
135 | inode = page->mapping->host; |
136 | |
137 | if (file) { |
138 | key = file->private_data; |
139 | ASSERT(key != NULL); |
140 | } else { |
141 | key = afs_request_key(AFS_FS_S(inode->i_sb)->volume->cell); |
142 | if (IS_ERR(key)) { |
143 | ret = PTR_ERR(key); |
144 | goto error_nokey; |
145 | } |
146 | } |
147 | |
148 | _enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index); |
149 | |
150 | vnode = AFS_FS_I(inode); |
151 | |
152 | BUG_ON(!PageLocked(page)); |
153 | |
154 | ret = -ESTALE; |
155 | if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) |
156 | goto error; |
157 | |
158 | /* is it cached? */ |
159 | #ifdef CONFIG_AFS_FSCACHE |
160 | ret = fscache_read_or_alloc_page(vnode->cache, |
161 | page, |
162 | afs_file_readpage_read_complete, |
163 | NULL, |
164 | GFP_KERNEL); |
165 | #else |
166 | ret = -ENOBUFS; |
167 | #endif |
168 | switch (ret) { |
169 | /* read BIO submitted (page in cache) */ |
170 | case 0: |
171 | break; |
172 | |
173 | /* page not yet cached */ |
174 | case -ENODATA: |
175 | _debug("cache said ENODATA"); |
176 | goto go_on; |
177 | |
178 | /* page will not be cached */ |
179 | case -ENOBUFS: |
180 | _debug("cache said ENOBUFS"); |
181 | default: |
182 | go_on: |
183 | offset = page->index << PAGE_CACHE_SHIFT; |
184 | len = min_t(size_t, i_size_read(inode) - offset, PAGE_SIZE); |
185 | |
186 | /* read the contents of the file from the server into the |
187 | * page */ |
188 | ret = afs_vnode_fetch_data(vnode, key, offset, len, page); |
189 | if (ret < 0) { |
190 | if (ret == -ENOENT) { |
191 | _debug("got NOENT from server" |
192 | " - marking file deleted and stale"); |
193 | set_bit(AFS_VNODE_DELETED, &vnode->flags); |
194 | ret = -ESTALE; |
195 | } |
196 | |
197 | #ifdef CONFIG_AFS_FSCACHE |
198 | fscache_uncache_page(vnode->cache, page); |
199 | #endif |
200 | BUG_ON(PageFsCache(page)); |
201 | goto error; |
202 | } |
203 | |
204 | SetPageUptodate(page); |
205 | |
206 | /* send the page to the cache */ |
207 | #ifdef CONFIG_AFS_FSCACHE |
208 | if (PageFsCache(page) && |
209 | fscache_write_page(vnode->cache, page, GFP_KERNEL) != 0) { |
210 | fscache_uncache_page(vnode->cache, page); |
211 | BUG_ON(PageFsCache(page)); |
212 | } |
213 | #endif |
214 | unlock_page(page); |
215 | } |
216 | |
217 | if (!file) |
218 | key_put(key); |
219 | _leave(" = 0"); |
220 | return 0; |
221 | |
222 | error: |
223 | SetPageError(page); |
224 | unlock_page(page); |
225 | if (!file) |
226 | key_put(key); |
227 | error_nokey: |
228 | _leave(" = %d", ret); |
229 | return ret; |
230 | } |
231 | |
232 | /* |
233 | * read a set of pages |
234 | */ |
235 | static int afs_readpages(struct file *file, struct address_space *mapping, |
236 | struct list_head *pages, unsigned nr_pages) |
237 | { |
238 | struct afs_vnode *vnode; |
239 | int ret = 0; |
240 | |
241 | _enter(",{%lu},,%d", mapping->host->i_ino, nr_pages); |
242 | |
243 | vnode = AFS_FS_I(mapping->host); |
244 | if (vnode->flags & AFS_VNODE_DELETED) { |
245 | _leave(" = -ESTALE"); |
246 | return -ESTALE; |
247 | } |
248 | |
249 | /* attempt to read as many of the pages as possible */ |
250 | #ifdef CONFIG_AFS_FSCACHE |
251 | ret = fscache_read_or_alloc_pages(vnode->cache, |
252 | mapping, |
253 | pages, |
254 | &nr_pages, |
255 | afs_file_readpage_read_complete, |
256 | NULL, |
257 | mapping_gfp_mask(mapping)); |
258 | #else |
259 | ret = -ENOBUFS; |
260 | #endif |
261 | |
262 | switch (ret) { |
263 | /* all pages are being read from the cache */ |
264 | case 0: |
265 | BUG_ON(!list_empty(pages)); |
266 | BUG_ON(nr_pages != 0); |
267 | _leave(" = 0 [reading all]"); |
268 | return 0; |
269 | |
270 | /* there were pages that couldn't be read from the cache */ |
271 | case -ENODATA: |
272 | case -ENOBUFS: |
273 | break; |
274 | |
275 | /* other error */ |
276 | default: |
277 | _leave(" = %d", ret); |
278 | return ret; |
279 | } |
280 | |
281 | /* load the missing pages from the network */ |
282 | ret = read_cache_pages(mapping, pages, (void *) afs_readpage, file); |
283 | |
284 | _leave(" = %d [netting]", ret); |
285 | return ret; |
286 | } |
287 | |
288 | /* |
289 | * write back a dirty page |
290 | */ |
291 | static int afs_launder_page(struct page *page) |
292 | { |
293 | _enter("{%lu}", page->index); |
294 | |
295 | return 0; |
296 | } |
297 | |
298 | /* |
299 | * invalidate part or all of a page |
300 | * - release a page and clean up its private data if offset is 0 (indicating |
301 | * the entire page) |
302 | */ |
303 | static void afs_invalidatepage(struct page *page, unsigned long offset) |
304 | { |
305 | struct afs_writeback *wb = (struct afs_writeback *) page_private(page); |
306 | |
307 | _enter("{%lu},%lu", page->index, offset); |
308 | |
309 | BUG_ON(!PageLocked(page)); |
310 | |
311 | /* we clean up only if the entire page is being invalidated */ |
312 | if (offset == 0) { |
313 | #ifdef CONFIG_AFS_FSCACHE |
314 | if (PageFsCache(page)) { |
315 | struct afs_vnode *vnode = AFS_FS_I(page->mapping->host); |
316 | fscache_wait_on_page_write(vnode->cache, page); |
317 | fscache_uncache_page(vnode->cache, page); |
318 | ClearPageFsCache(page); |
319 | } |
320 | #endif |
321 | |
322 | if (PagePrivate(page)) { |
323 | if (wb && !PageWriteback(page)) { |
324 | set_page_private(page, 0); |
325 | afs_put_writeback(wb); |
326 | } |
327 | |
328 | if (!page_private(page)) |
329 | ClearPagePrivate(page); |
330 | } |
331 | } |
332 | |
333 | _leave(""); |
334 | } |
335 | |
336 | /* |
337 | * release a page and clean up its private state if it's not busy |
338 | * - return true if the page can now be released, false if not |
339 | */ |
340 | static int afs_releasepage(struct page *page, gfp_t gfp_flags) |
341 | { |
342 | struct afs_writeback *wb = (struct afs_writeback *) page_private(page); |
343 | struct afs_vnode *vnode = AFS_FS_I(page->mapping->host); |
344 | |
345 | _enter("{{%x:%u}[%lu],%lx},%x", |
346 | vnode->fid.vid, vnode->fid.vnode, page->index, page->flags, |
347 | gfp_flags); |
348 | |
349 | /* deny if page is being written to the cache and the caller hasn't |
350 | * elected to wait */ |
351 | #ifdef CONFIG_AFS_FSCACHE |
352 | if (PageFsCache(page)) { |
353 | if (fscache_check_page_write(vnode->cache, page)) { |
354 | if (!(gfp_flags & __GFP_WAIT)) { |
355 | _leave(" = F [cache busy]"); |
356 | return 0; |
357 | } |
358 | fscache_wait_on_page_write(vnode->cache, page); |
359 | } |
360 | |
361 | fscache_uncache_page(vnode->cache, page); |
362 | ClearPageFsCache(page); |
363 | } |
364 | #endif |
365 | |
366 | if (PagePrivate(page)) { |
367 | if (wb) { |
368 | set_page_private(page, 0); |
369 | afs_put_writeback(wb); |
370 | } |
371 | ClearPagePrivate(page); |
372 | } |
373 | |
374 | /* indicate that the page can be released */ |
375 | _leave(" = T"); |
376 | return 1; |
377 | } |
378 |
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