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Linux/fs/afs/file.c

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  1 // SPDX-License-Identifier: GPL-2.0-or-later
  2 /* AFS filesystem file handling
  3  *
  4  * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
  5  * Written by David Howells (dhowells@redhat.com)
  6  */
  7 
  8 #include <linux/kernel.h>
  9 #include <linux/module.h>
 10 #include <linux/init.h>
 11 #include <linux/fs.h>
 12 #include <linux/pagemap.h>
 13 #include <linux/writeback.h>
 14 #include <linux/gfp.h>
 15 #include <linux/task_io_accounting_ops.h>
 16 #include <linux/mm.h>
 17 #include "internal.h"
 18 
 19 static int afs_file_mmap(struct file *file, struct vm_area_struct *vma);
 20 static int afs_readpage(struct file *file, struct page *page);
 21 static void afs_invalidatepage(struct page *page, unsigned int offset,
 22                                unsigned int length);
 23 static int afs_releasepage(struct page *page, gfp_t gfp_flags);
 24 
 25 static int afs_readpages(struct file *filp, struct address_space *mapping,
 26                          struct list_head *pages, unsigned nr_pages);
 27 
 28 const struct file_operations afs_file_operations = {
 29         .open           = afs_open,
 30         .release        = afs_release,
 31         .llseek         = generic_file_llseek,
 32         .read_iter      = generic_file_read_iter,
 33         .write_iter     = afs_file_write,
 34         .mmap           = afs_file_mmap,
 35         .splice_read    = generic_file_splice_read,
 36         .fsync          = afs_fsync,
 37         .lock           = afs_lock,
 38         .flock          = afs_flock,
 39 };
 40 
 41 const struct inode_operations afs_file_inode_operations = {
 42         .getattr        = afs_getattr,
 43         .setattr        = afs_setattr,
 44         .permission     = afs_permission,
 45         .listxattr      = afs_listxattr,
 46 };
 47 
 48 const struct address_space_operations afs_fs_aops = {
 49         .readpage       = afs_readpage,
 50         .readpages      = afs_readpages,
 51         .set_page_dirty = afs_set_page_dirty,
 52         .launder_page   = afs_launder_page,
 53         .releasepage    = afs_releasepage,
 54         .invalidatepage = afs_invalidatepage,
 55         .write_begin    = afs_write_begin,
 56         .write_end      = afs_write_end,
 57         .writepage      = afs_writepage,
 58         .writepages     = afs_writepages,
 59 };
 60 
 61 static const struct vm_operations_struct afs_vm_ops = {
 62         .fault          = filemap_fault,
 63         .map_pages      = filemap_map_pages,
 64         .page_mkwrite   = afs_page_mkwrite,
 65 };
 66 
 67 /*
 68  * Discard a pin on a writeback key.
 69  */
 70 void afs_put_wb_key(struct afs_wb_key *wbk)
 71 {
 72         if (refcount_dec_and_test(&wbk->usage)) {
 73                 key_put(wbk->key);
 74                 kfree(wbk);
 75         }
 76 }
 77 
 78 /*
 79  * Cache key for writeback.
 80  */
 81 int afs_cache_wb_key(struct afs_vnode *vnode, struct afs_file *af)
 82 {
 83         struct afs_wb_key *wbk, *p;
 84 
 85         wbk = kzalloc(sizeof(struct afs_wb_key), GFP_KERNEL);
 86         if (!wbk)
 87                 return -ENOMEM;
 88         refcount_set(&wbk->usage, 2);
 89         wbk->key = af->key;
 90 
 91         spin_lock(&vnode->wb_lock);
 92         list_for_each_entry(p, &vnode->wb_keys, vnode_link) {
 93                 if (p->key == wbk->key)
 94                         goto found;
 95         }
 96 
 97         key_get(wbk->key);
 98         list_add_tail(&wbk->vnode_link, &vnode->wb_keys);
 99         spin_unlock(&vnode->wb_lock);
100         af->wb = wbk;
101         return 0;
102 
103 found:
104         refcount_inc(&p->usage);
105         spin_unlock(&vnode->wb_lock);
106         af->wb = p;
107         kfree(wbk);
108         return 0;
109 }
110 
111 /*
112  * open an AFS file or directory and attach a key to it
113  */
114 int afs_open(struct inode *inode, struct file *file)
115 {
116         struct afs_vnode *vnode = AFS_FS_I(inode);
117         struct afs_file *af;
118         struct key *key;
119         int ret;
120 
121         _enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);
122 
123         key = afs_request_key(vnode->volume->cell);
124         if (IS_ERR(key)) {
125                 ret = PTR_ERR(key);
126                 goto error;
127         }
128 
129         af = kzalloc(sizeof(*af), GFP_KERNEL);
130         if (!af) {
131                 ret = -ENOMEM;
132                 goto error_key;
133         }
134         af->key = key;
135 
136         ret = afs_validate(vnode, key);
137         if (ret < 0)
138                 goto error_af;
139 
140         if (file->f_mode & FMODE_WRITE) {
141                 ret = afs_cache_wb_key(vnode, af);
142                 if (ret < 0)
143                         goto error_af;
144         }
145 
146         if (file->f_flags & O_TRUNC)
147                 set_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
148         
149         file->private_data = af;
150         _leave(" = 0");
151         return 0;
152 
153 error_af:
154         kfree(af);
155 error_key:
156         key_put(key);
157 error:
158         _leave(" = %d", ret);
159         return ret;
160 }
161 
162 /*
163  * release an AFS file or directory and discard its key
164  */
165 int afs_release(struct inode *inode, struct file *file)
166 {
167         struct afs_vnode *vnode = AFS_FS_I(inode);
168         struct afs_file *af = file->private_data;
169         int ret = 0;
170 
171         _enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);
172 
173         if ((file->f_mode & FMODE_WRITE))
174                 ret = vfs_fsync(file, 0);
175 
176         file->private_data = NULL;
177         if (af->wb)
178                 afs_put_wb_key(af->wb);
179         key_put(af->key);
180         kfree(af);
181         afs_prune_wb_keys(vnode);
182         _leave(" = %d", ret);
183         return ret;
184 }
185 
186 /*
187  * Dispose of a ref to a read record.
188  */
189 void afs_put_read(struct afs_read *req)
190 {
191         int i;
192 
193         if (refcount_dec_and_test(&req->usage)) {
194                 if (req->pages) {
195                         for (i = 0; i < req->nr_pages; i++)
196                                 if (req->pages[i])
197                                         put_page(req->pages[i]);
198                         if (req->pages != req->array)
199                                 kfree(req->pages);
200                 }
201                 kfree(req);
202         }
203 }
204 
205 #ifdef CONFIG_AFS_FSCACHE
206 /*
207  * deal with notification that a page was read from the cache
208  */
209 static void afs_file_readpage_read_complete(struct page *page,
210                                             void *data,
211                                             int error)
212 {
213         _enter("%p,%p,%d", page, data, error);
214 
215         /* if the read completes with an error, we just unlock the page and let
216          * the VM reissue the readpage */
217         if (!error)
218                 SetPageUptodate(page);
219         unlock_page(page);
220 }
221 #endif
222 
223 /*
224  * Fetch file data from the volume.
225  */
226 int afs_fetch_data(struct afs_vnode *vnode, struct key *key, struct afs_read *desc)
227 {
228         struct afs_fs_cursor fc;
229         struct afs_status_cb *scb;
230         int ret;
231 
232         _enter("%s{%llx:%llu.%u},%x,,,",
233                vnode->volume->name,
234                vnode->fid.vid,
235                vnode->fid.vnode,
236                vnode->fid.unique,
237                key_serial(key));
238 
239         scb = kzalloc(sizeof(struct afs_status_cb), GFP_KERNEL);
240         if (!scb)
241                 return -ENOMEM;
242 
243         ret = -ERESTARTSYS;
244         if (afs_begin_vnode_operation(&fc, vnode, key, true)) {
245                 afs_dataversion_t data_version = vnode->status.data_version;
246 
247                 while (afs_select_fileserver(&fc)) {
248                         fc.cb_break = afs_calc_vnode_cb_break(vnode);
249                         afs_fs_fetch_data(&fc, scb, desc);
250                 }
251 
252                 afs_check_for_remote_deletion(&fc, vnode);
253                 afs_vnode_commit_status(&fc, vnode, fc.cb_break,
254                                         &data_version, scb);
255                 ret = afs_end_vnode_operation(&fc);
256         }
257 
258         if (ret == 0) {
259                 afs_stat_v(vnode, n_fetches);
260                 atomic_long_add(desc->actual_len,
261                                 &afs_v2net(vnode)->n_fetch_bytes);
262         }
263 
264         kfree(scb);
265         _leave(" = %d", ret);
266         return ret;
267 }
268 
269 /*
270  * read page from file, directory or symlink, given a key to use
271  */
272 int afs_page_filler(void *data, struct page *page)
273 {
274         struct inode *inode = page->mapping->host;
275         struct afs_vnode *vnode = AFS_FS_I(inode);
276         struct afs_read *req;
277         struct key *key = data;
278         int ret;
279 
280         _enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
281 
282         BUG_ON(!PageLocked(page));
283 
284         ret = -ESTALE;
285         if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
286                 goto error;
287 
288         /* is it cached? */
289 #ifdef CONFIG_AFS_FSCACHE
290         ret = fscache_read_or_alloc_page(vnode->cache,
291                                          page,
292                                          afs_file_readpage_read_complete,
293                                          NULL,
294                                          GFP_KERNEL);
295 #else
296         ret = -ENOBUFS;
297 #endif
298         switch (ret) {
299                 /* read BIO submitted (page in cache) */
300         case 0:
301                 break;
302 
303                 /* page not yet cached */
304         case -ENODATA:
305                 _debug("cache said ENODATA");
306                 goto go_on;
307 
308                 /* page will not be cached */
309         case -ENOBUFS:
310                 _debug("cache said ENOBUFS");
311 
312                 /* fall through */
313         default:
314         go_on:
315                 req = kzalloc(struct_size(req, array, 1), GFP_KERNEL);
316                 if (!req)
317                         goto enomem;
318 
319                 /* We request a full page.  If the page is a partial one at the
320                  * end of the file, the server will return a short read and the
321                  * unmarshalling code will clear the unfilled space.
322                  */
323                 refcount_set(&req->usage, 1);
324                 req->pos = (loff_t)page->index << PAGE_SHIFT;
325                 req->len = PAGE_SIZE;
326                 req->nr_pages = 1;
327                 req->pages = req->array;
328                 req->pages[0] = page;
329                 get_page(page);
330 
331                 /* read the contents of the file from the server into the
332                  * page */
333                 ret = afs_fetch_data(vnode, key, req);
334                 afs_put_read(req);
335 
336                 if (ret < 0) {
337                         if (ret == -ENOENT) {
338                                 _debug("got NOENT from server"
339                                        " - marking file deleted and stale");
340                                 set_bit(AFS_VNODE_DELETED, &vnode->flags);
341                                 ret = -ESTALE;
342                         }
343 
344 #ifdef CONFIG_AFS_FSCACHE
345                         fscache_uncache_page(vnode->cache, page);
346 #endif
347                         BUG_ON(PageFsCache(page));
348 
349                         if (ret == -EINTR ||
350                             ret == -ENOMEM ||
351                             ret == -ERESTARTSYS ||
352                             ret == -EAGAIN)
353                                 goto error;
354                         goto io_error;
355                 }
356 
357                 SetPageUptodate(page);
358 
359                 /* send the page to the cache */
360 #ifdef CONFIG_AFS_FSCACHE
361                 if (PageFsCache(page) &&
362                     fscache_write_page(vnode->cache, page, vnode->status.size,
363                                        GFP_KERNEL) != 0) {
364                         fscache_uncache_page(vnode->cache, page);
365                         BUG_ON(PageFsCache(page));
366                 }
367 #endif
368                 unlock_page(page);
369         }
370 
371         _leave(" = 0");
372         return 0;
373 
374 io_error:
375         SetPageError(page);
376         goto error;
377 enomem:
378         ret = -ENOMEM;
379 error:
380         unlock_page(page);
381         _leave(" = %d", ret);
382         return ret;
383 }
384 
385 /*
386  * read page from file, directory or symlink, given a file to nominate the key
387  * to be used
388  */
389 static int afs_readpage(struct file *file, struct page *page)
390 {
391         struct key *key;
392         int ret;
393 
394         if (file) {
395                 key = afs_file_key(file);
396                 ASSERT(key != NULL);
397                 ret = afs_page_filler(key, page);
398         } else {
399                 struct inode *inode = page->mapping->host;
400                 key = afs_request_key(AFS_FS_S(inode->i_sb)->cell);
401                 if (IS_ERR(key)) {
402                         ret = PTR_ERR(key);
403                 } else {
404                         ret = afs_page_filler(key, page);
405                         key_put(key);
406                 }
407         }
408         return ret;
409 }
410 
411 /*
412  * Make pages available as they're filled.
413  */
414 static void afs_readpages_page_done(struct afs_read *req)
415 {
416 #ifdef CONFIG_AFS_FSCACHE
417         struct afs_vnode *vnode = req->vnode;
418 #endif
419         struct page *page = req->pages[req->index];
420 
421         req->pages[req->index] = NULL;
422         SetPageUptodate(page);
423 
424         /* send the page to the cache */
425 #ifdef CONFIG_AFS_FSCACHE
426         if (PageFsCache(page) &&
427             fscache_write_page(vnode->cache, page, vnode->status.size,
428                                GFP_KERNEL) != 0) {
429                 fscache_uncache_page(vnode->cache, page);
430                 BUG_ON(PageFsCache(page));
431         }
432 #endif
433         unlock_page(page);
434         put_page(page);
435 }
436 
437 /*
438  * Read a contiguous set of pages.
439  */
440 static int afs_readpages_one(struct file *file, struct address_space *mapping,
441                              struct list_head *pages)
442 {
443         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
444         struct afs_read *req;
445         struct list_head *p;
446         struct page *first, *page;
447         struct key *key = afs_file_key(file);
448         pgoff_t index;
449         int ret, n, i;
450 
451         /* Count the number of contiguous pages at the front of the list.  Note
452          * that the list goes prev-wards rather than next-wards.
453          */
454         first = lru_to_page(pages);
455         index = first->index + 1;
456         n = 1;
457         for (p = first->lru.prev; p != pages; p = p->prev) {
458                 page = list_entry(p, struct page, lru);
459                 if (page->index != index)
460                         break;
461                 index++;
462                 n++;
463         }
464 
465         req = kzalloc(struct_size(req, array, n), GFP_NOFS);
466         if (!req)
467                 return -ENOMEM;
468 
469         refcount_set(&req->usage, 1);
470         req->vnode = vnode;
471         req->page_done = afs_readpages_page_done;
472         req->pos = first->index;
473         req->pos <<= PAGE_SHIFT;
474         req->pages = req->array;
475 
476         /* Transfer the pages to the request.  We add them in until one fails
477          * to add to the LRU and then we stop (as that'll make a hole in the
478          * contiguous run.
479          *
480          * Note that it's possible for the file size to change whilst we're
481          * doing this, but we rely on the server returning less than we asked
482          * for if the file shrank.  We also rely on this to deal with a partial
483          * page at the end of the file.
484          */
485         do {
486                 page = lru_to_page(pages);
487                 list_del(&page->lru);
488                 index = page->index;
489                 if (add_to_page_cache_lru(page, mapping, index,
490                                           readahead_gfp_mask(mapping))) {
491 #ifdef CONFIG_AFS_FSCACHE
492                         fscache_uncache_page(vnode->cache, page);
493 #endif
494                         put_page(page);
495                         break;
496                 }
497 
498                 req->pages[req->nr_pages++] = page;
499                 req->len += PAGE_SIZE;
500         } while (req->nr_pages < n);
501 
502         if (req->nr_pages == 0) {
503                 kfree(req);
504                 return 0;
505         }
506 
507         ret = afs_fetch_data(vnode, key, req);
508         if (ret < 0)
509                 goto error;
510 
511         task_io_account_read(PAGE_SIZE * req->nr_pages);
512         afs_put_read(req);
513         return 0;
514 
515 error:
516         if (ret == -ENOENT) {
517                 _debug("got NOENT from server"
518                        " - marking file deleted and stale");
519                 set_bit(AFS_VNODE_DELETED, &vnode->flags);
520                 ret = -ESTALE;
521         }
522 
523         for (i = 0; i < req->nr_pages; i++) {
524                 page = req->pages[i];
525                 if (page) {
526 #ifdef CONFIG_AFS_FSCACHE
527                         fscache_uncache_page(vnode->cache, page);
528 #endif
529                         SetPageError(page);
530                         unlock_page(page);
531                 }
532         }
533 
534         afs_put_read(req);
535         return ret;
536 }
537 
538 /*
539  * read a set of pages
540  */
541 static int afs_readpages(struct file *file, struct address_space *mapping,
542                          struct list_head *pages, unsigned nr_pages)
543 {
544         struct key *key = afs_file_key(file);
545         struct afs_vnode *vnode;
546         int ret = 0;
547 
548         _enter("{%d},{%lu},,%d",
549                key_serial(key), mapping->host->i_ino, nr_pages);
550 
551         ASSERT(key != NULL);
552 
553         vnode = AFS_FS_I(mapping->host);
554         if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
555                 _leave(" = -ESTALE");
556                 return -ESTALE;
557         }
558 
559         /* attempt to read as many of the pages as possible */
560 #ifdef CONFIG_AFS_FSCACHE
561         ret = fscache_read_or_alloc_pages(vnode->cache,
562                                           mapping,
563                                           pages,
564                                           &nr_pages,
565                                           afs_file_readpage_read_complete,
566                                           NULL,
567                                           mapping_gfp_mask(mapping));
568 #else
569         ret = -ENOBUFS;
570 #endif
571 
572         switch (ret) {
573                 /* all pages are being read from the cache */
574         case 0:
575                 BUG_ON(!list_empty(pages));
576                 BUG_ON(nr_pages != 0);
577                 _leave(" = 0 [reading all]");
578                 return 0;
579 
580                 /* there were pages that couldn't be read from the cache */
581         case -ENODATA:
582         case -ENOBUFS:
583                 break;
584 
585                 /* other error */
586         default:
587                 _leave(" = %d", ret);
588                 return ret;
589         }
590 
591         while (!list_empty(pages)) {
592                 ret = afs_readpages_one(file, mapping, pages);
593                 if (ret < 0)
594                         break;
595         }
596 
597         _leave(" = %d [netting]", ret);
598         return ret;
599 }
600 
601 /*
602  * invalidate part or all of a page
603  * - release a page and clean up its private data if offset is 0 (indicating
604  *   the entire page)
605  */
606 static void afs_invalidatepage(struct page *page, unsigned int offset,
607                                unsigned int length)
608 {
609         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
610         unsigned long priv;
611 
612         _enter("{%lu},%u,%u", page->index, offset, length);
613 
614         BUG_ON(!PageLocked(page));
615 
616         /* we clean up only if the entire page is being invalidated */
617         if (offset == 0 && length == PAGE_SIZE) {
618 #ifdef CONFIG_AFS_FSCACHE
619                 if (PageFsCache(page)) {
620                         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
621                         fscache_wait_on_page_write(vnode->cache, page);
622                         fscache_uncache_page(vnode->cache, page);
623                 }
624 #endif
625 
626                 if (PagePrivate(page)) {
627                         priv = page_private(page);
628                         trace_afs_page_dirty(vnode, tracepoint_string("inval"),
629                                              page->index, priv);
630                         set_page_private(page, 0);
631                         ClearPagePrivate(page);
632                 }
633         }
634 
635         _leave("");
636 }
637 
638 /*
639  * release a page and clean up its private state if it's not busy
640  * - return true if the page can now be released, false if not
641  */
642 static int afs_releasepage(struct page *page, gfp_t gfp_flags)
643 {
644         struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
645         unsigned long priv;
646 
647         _enter("{{%llx:%llu}[%lu],%lx},%x",
648                vnode->fid.vid, vnode->fid.vnode, page->index, page->flags,
649                gfp_flags);
650 
651         /* deny if page is being written to the cache and the caller hasn't
652          * elected to wait */
653 #ifdef CONFIG_AFS_FSCACHE
654         if (!fscache_maybe_release_page(vnode->cache, page, gfp_flags)) {
655                 _leave(" = F [cache busy]");
656                 return 0;
657         }
658 #endif
659 
660         if (PagePrivate(page)) {
661                 priv = page_private(page);
662                 trace_afs_page_dirty(vnode, tracepoint_string("rel"),
663                                      page->index, priv);
664                 set_page_private(page, 0);
665                 ClearPagePrivate(page);
666         }
667 
668         /* indicate that the page can be released */
669         _leave(" = T");
670         return 1;
671 }
672 
673 /*
674  * Handle setting up a memory mapping on an AFS file.
675  */
676 static int afs_file_mmap(struct file *file, struct vm_area_struct *vma)
677 {
678         int ret;
679 
680         ret = generic_file_mmap(file, vma);
681         if (ret == 0)
682                 vma->vm_ops = &afs_vm_ops;
683         return ret;
684 }
685 

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