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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 int offset,
 23                                unsigned int length);
 24 static int afs_releasepage(struct page *page, gfp_t gfp_flags);
 25 static int afs_launder_page(struct page *page);
 26 
 27 static int afs_readpages(struct file *filp, struct address_space *mapping,
 28                          struct list_head *pages, unsigned nr_pages);
 29 
 30 const struct file_operations afs_file_operations = {
 31         .open           = afs_open,
 32         .release        = afs_release,
 33         .llseek         = generic_file_llseek,
 34         .read_iter      = generic_file_read_iter,
 35         .write_iter     = afs_file_write,
 36         .mmap           = generic_file_readonly_mmap,
 37         .splice_read    = generic_file_splice_read,
 38         .fsync          = afs_fsync,
 39         .lock           = afs_lock,
 40         .flock          = afs_flock,
 41 };
 42 
 43 const struct inode_operations afs_file_inode_operations = {
 44         .getattr        = afs_getattr,
 45         .setattr        = afs_setattr,
 46         .permission     = afs_permission,
 47 };
 48 
 49 const struct address_space_operations afs_fs_aops = {
 50         .readpage       = afs_readpage,
 51         .readpages      = afs_readpages,
 52         .set_page_dirty = afs_set_page_dirty,
 53         .launder_page   = afs_launder_page,
 54         .releasepage    = afs_releasepage,
 55         .invalidatepage = afs_invalidatepage,
 56         .write_begin    = afs_write_begin,
 57         .write_end      = afs_write_end,
 58         .writepage      = afs_writepage,
 59         .writepages     = afs_writepages,
 60 };
 61 
 62 /*
 63  * open an AFS file or directory and attach a key to it
 64  */
 65 int afs_open(struct inode *inode, struct file *file)
 66 {
 67         struct afs_vnode *vnode = AFS_FS_I(inode);
 68         struct key *key;
 69         int ret;
 70 
 71         _enter("{%x:%u},", vnode->fid.vid, vnode->fid.vnode);
 72 
 73         key = afs_request_key(vnode->volume->cell);
 74         if (IS_ERR(key)) {
 75                 _leave(" = %ld [key]", PTR_ERR(key));
 76                 return PTR_ERR(key);
 77         }
 78 
 79         ret = afs_validate(vnode, key);
 80         if (ret < 0) {
 81                 _leave(" = %d [val]", ret);
 82                 return ret;
 83         }
 84 
 85         file->private_data = key;
 86         _leave(" = 0");
 87         return 0;
 88 }
 89 
 90 /*
 91  * release an AFS file or directory and discard its key
 92  */
 93 int afs_release(struct inode *inode, struct file *file)
 94 {
 95         struct afs_vnode *vnode = AFS_FS_I(inode);
 96 
 97         _enter("{%x:%u},", vnode->fid.vid, vnode->fid.vnode);
 98 
 99         key_put(file->private_data);
100         _leave(" = 0");
101         return 0;
102 }
103 
104 #ifdef CONFIG_AFS_FSCACHE
105 /*
106  * deal with notification that a page was read from the cache
107  */
108 static void afs_file_readpage_read_complete(struct page *page,
109                                             void *data,
110                                             int error)
111 {
112         _enter("%p,%p,%d", page, data, error);
113 
114         /* if the read completes with an error, we just unlock the page and let
115          * the VM reissue the readpage */
116         if (!error)
117                 SetPageUptodate(page);
118         unlock_page(page);
119 }
120 #endif
121 
122 /*
123  * read page from file, directory or symlink, given a key to use
124  */
125 int afs_page_filler(void *data, struct page *page)
126 {
127         struct inode *inode = page->mapping->host;
128         struct afs_vnode *vnode = AFS_FS_I(inode);
129         struct key *key = data;
130         size_t len;
131         off_t offset;
132         int ret;
133 
134         _enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
135 
136         BUG_ON(!PageLocked(page));
137 
138         ret = -ESTALE;
139         if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
140                 goto error;
141 
142         /* is it cached? */
143 #ifdef CONFIG_AFS_FSCACHE
144         ret = fscache_read_or_alloc_page(vnode->cache,
145                                          page,
146                                          afs_file_readpage_read_complete,
147                                          NULL,
148                                          GFP_KERNEL);
149 #else
150         ret = -ENOBUFS;
151 #endif
152         switch (ret) {
153                 /* read BIO submitted (page in cache) */
154         case 0:
155                 break;
156 
157                 /* page not yet cached */
158         case -ENODATA:
159                 _debug("cache said ENODATA");
160                 goto go_on;
161 
162                 /* page will not be cached */
163         case -ENOBUFS:
164                 _debug("cache said ENOBUFS");
165         default:
166         go_on:
167                 offset = page->index << PAGE_CACHE_SHIFT;
168                 len = min_t(size_t, i_size_read(inode) - offset, PAGE_SIZE);
169 
170                 /* read the contents of the file from the server into the
171                  * page */
172                 ret = afs_vnode_fetch_data(vnode, key, offset, len, page);
173                 if (ret < 0) {
174                         if (ret == -ENOENT) {
175                                 _debug("got NOENT from server"
176                                        " - marking file deleted and stale");
177                                 set_bit(AFS_VNODE_DELETED, &vnode->flags);
178                                 ret = -ESTALE;
179                         }
180 
181 #ifdef CONFIG_AFS_FSCACHE
182                         fscache_uncache_page(vnode->cache, page);
183 #endif
184                         BUG_ON(PageFsCache(page));
185                         goto error;
186                 }
187 
188                 SetPageUptodate(page);
189 
190                 /* send the page to the cache */
191 #ifdef CONFIG_AFS_FSCACHE
192                 if (PageFsCache(page) &&
193                     fscache_write_page(vnode->cache, page, GFP_KERNEL) != 0) {
194                         fscache_uncache_page(vnode->cache, page);
195                         BUG_ON(PageFsCache(page));
196                 }
197 #endif
198                 unlock_page(page);
199         }
200 
201         _leave(" = 0");
202         return 0;
203 
204 error:
205         SetPageError(page);
206         unlock_page(page);
207         _leave(" = %d", ret);
208         return ret;
209 }
210 
211 /*
212  * read page from file, directory or symlink, given a file to nominate the key
213  * to be used
214  */
215 static int afs_readpage(struct file *file, struct page *page)
216 {
217         struct key *key;
218         int ret;
219 
220         if (file) {
221                 key = file->private_data;
222                 ASSERT(key != NULL);
223                 ret = afs_page_filler(key, page);
224         } else {
225                 struct inode *inode = page->mapping->host;
226                 key = afs_request_key(AFS_FS_S(inode->i_sb)->volume->cell);
227                 if (IS_ERR(key)) {
228                         ret = PTR_ERR(key);
229                 } else {
230                         ret = afs_page_filler(key, page);
231                         key_put(key);
232                 }
233         }
234         return ret;
235 }
236 
237 /*
238  * read a set of pages
239  */
240 static int afs_readpages(struct file *file, struct address_space *mapping,
241                          struct list_head *pages, unsigned nr_pages)
242 {
243         struct key *key = file->private_data;
244         struct afs_vnode *vnode;
245         int ret = 0;
246 
247         _enter("{%d},{%lu},,%d",
248                key_serial(key), mapping->host->i_ino, nr_pages);
249 
250         ASSERT(key != NULL);
251 
252         vnode = AFS_FS_I(mapping->host);
253         if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
254                 _leave(" = -ESTALE");
255                 return -ESTALE;
256         }
257 
258         /* attempt to read as many of the pages as possible */
259 #ifdef CONFIG_AFS_FSCACHE
260         ret = fscache_read_or_alloc_pages(vnode->cache,
261                                           mapping,
262                                           pages,
263                                           &nr_pages,
264                                           afs_file_readpage_read_complete,
265                                           NULL,
266                                           mapping_gfp_mask(mapping));
267 #else
268         ret = -ENOBUFS;
269 #endif
270 
271         switch (ret) {
272                 /* all pages are being read from the cache */
273         case 0:
274                 BUG_ON(!list_empty(pages));
275                 BUG_ON(nr_pages != 0);
276                 _leave(" = 0 [reading all]");
277                 return 0;
278 
279                 /* there were pages that couldn't be read from the cache */
280         case -ENODATA:
281         case -ENOBUFS:
282                 break;
283 
284                 /* other error */
285         default:
286                 _leave(" = %d", ret);
287                 return ret;
288         }
289 
290         /* load the missing pages from the network */
291         ret = read_cache_pages(mapping, pages, afs_page_filler, key);
292 
293         _leave(" = %d [netting]", ret);
294         return ret;
295 }
296 
297 /*
298  * write back a dirty page
299  */
300 static int afs_launder_page(struct page *page)
301 {
302         _enter("{%lu}", page->index);
303 
304         return 0;
305 }
306 
307 /*
308  * invalidate part or all of a page
309  * - release a page and clean up its private data if offset is 0 (indicating
310  *   the entire page)
311  */
312 static void afs_invalidatepage(struct page *page, unsigned int offset,
313                                unsigned int length)
314 {
315         struct afs_writeback *wb = (struct afs_writeback *) page_private(page);
316 
317         _enter("{%lu},%u,%u", page->index, offset, length);
318 
319         BUG_ON(!PageLocked(page));
320 
321         /* we clean up only if the entire page is being invalidated */
322         if (offset == 0 && length == PAGE_CACHE_SIZE) {
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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