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Linux/fs/afs/write.c

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  1 /* handling of writes to regular files and writing back to the server
  2  *
  3  * Copyright (C) 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/backing-dev.h>
 13 #include <linux/slab.h>
 14 #include <linux/fs.h>
 15 #include <linux/pagemap.h>
 16 #include <linux/writeback.h>
 17 #include <linux/pagevec.h>
 18 #include "internal.h"
 19 
 20 /*
 21  * mark a page as having been made dirty and thus needing writeback
 22  */
 23 int afs_set_page_dirty(struct page *page)
 24 {
 25         _enter("");
 26         return __set_page_dirty_nobuffers(page);
 27 }
 28 
 29 /*
 30  * partly or wholly fill a page that's under preparation for writing
 31  */
 32 static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
 33                          loff_t pos, unsigned int len, struct page *page)
 34 {
 35         struct afs_read *req;
 36         size_t p;
 37         void *data;
 38         int ret;
 39 
 40         _enter(",,%llu", (unsigned long long)pos);
 41 
 42         if (pos >= vnode->vfs_inode.i_size) {
 43                 p = pos & ~PAGE_MASK;
 44                 ASSERTCMP(p + len, <=, PAGE_SIZE);
 45                 data = kmap(page);
 46                 memset(data + p, 0, len);
 47                 kunmap(page);
 48                 return 0;
 49         }
 50 
 51         req = kzalloc(sizeof(struct afs_read) + sizeof(struct page *),
 52                       GFP_KERNEL);
 53         if (!req)
 54                 return -ENOMEM;
 55 
 56         refcount_set(&req->usage, 1);
 57         req->pos = pos;
 58         req->len = len;
 59         req->nr_pages = 1;
 60         req->pages = req->array;
 61         req->pages[0] = page;
 62         get_page(page);
 63 
 64         ret = afs_fetch_data(vnode, key, req);
 65         afs_put_read(req);
 66         if (ret < 0) {
 67                 if (ret == -ENOENT) {
 68                         _debug("got NOENT from server"
 69                                " - marking file deleted and stale");
 70                         set_bit(AFS_VNODE_DELETED, &vnode->flags);
 71                         ret = -ESTALE;
 72                 }
 73         }
 74 
 75         _leave(" = %d", ret);
 76         return ret;
 77 }
 78 
 79 /*
 80  * prepare to perform part of a write to a page
 81  */
 82 int afs_write_begin(struct file *file, struct address_space *mapping,
 83                     loff_t pos, unsigned len, unsigned flags,
 84                     struct page **pagep, void **fsdata)
 85 {
 86         struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
 87         struct page *page;
 88         struct key *key = afs_file_key(file);
 89         unsigned long priv;
 90         unsigned f, from = pos & (PAGE_SIZE - 1);
 91         unsigned t, to = from + len;
 92         pgoff_t index = pos >> PAGE_SHIFT;
 93         int ret;
 94 
 95         _enter("{%llx:%llu},{%lx},%u,%u",
 96                vnode->fid.vid, vnode->fid.vnode, index, from, to);
 97 
 98         /* We want to store information about how much of a page is altered in
 99          * page->private.
100          */
101         BUILD_BUG_ON(PAGE_SIZE > 32768 && sizeof(page->private) < 8);
102 
103         page = grab_cache_page_write_begin(mapping, index, flags);
104         if (!page)
105                 return -ENOMEM;
106 
107         if (!PageUptodate(page) && len != PAGE_SIZE) {
108                 ret = afs_fill_page(vnode, key, pos & PAGE_MASK, PAGE_SIZE, page);
109                 if (ret < 0) {
110                         unlock_page(page);
111                         put_page(page);
112                         _leave(" = %d [prep]", ret);
113                         return ret;
114                 }
115                 SetPageUptodate(page);
116         }
117 
118         /* page won't leak in error case: it eventually gets cleaned off LRU */
119         *pagep = page;
120 
121 try_again:
122         /* See if this page is already partially written in a way that we can
123          * merge the new write with.
124          */
125         t = f = 0;
126         if (PagePrivate(page)) {
127                 priv = page_private(page);
128                 f = priv & AFS_PRIV_MAX;
129                 t = priv >> AFS_PRIV_SHIFT;
130                 ASSERTCMP(f, <=, t);
131         }
132 
133         if (f != t) {
134                 if (PageWriteback(page)) {
135                         trace_afs_page_dirty(vnode, tracepoint_string("alrdy"),
136                                              page->index, priv);
137                         goto flush_conflicting_write;
138                 }
139                 /* If the file is being filled locally, allow inter-write
140                  * spaces to be merged into writes.  If it's not, only write
141                  * back what the user gives us.
142                  */
143                 if (!test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags) &&
144                     (to < f || from > t))
145                         goto flush_conflicting_write;
146                 if (from < f)
147                         f = from;
148                 if (to > t)
149                         t = to;
150         } else {
151                 f = from;
152                 t = to;
153         }
154 
155         priv = (unsigned long)t << AFS_PRIV_SHIFT;
156         priv |= f;
157         trace_afs_page_dirty(vnode, tracepoint_string("begin"),
158                              page->index, priv);
159         SetPagePrivate(page);
160         set_page_private(page, priv);
161         _leave(" = 0");
162         return 0;
163 
164         /* The previous write and this write aren't adjacent or overlapping, so
165          * flush the page out.
166          */
167 flush_conflicting_write:
168         _debug("flush conflict");
169         ret = write_one_page(page);
170         if (ret < 0) {
171                 _leave(" = %d", ret);
172                 return ret;
173         }
174 
175         ret = lock_page_killable(page);
176         if (ret < 0) {
177                 _leave(" = %d", ret);
178                 return ret;
179         }
180         goto try_again;
181 }
182 
183 /*
184  * finalise part of a write to a page
185  */
186 int afs_write_end(struct file *file, struct address_space *mapping,
187                   loff_t pos, unsigned len, unsigned copied,
188                   struct page *page, void *fsdata)
189 {
190         struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
191         struct key *key = afs_file_key(file);
192         loff_t i_size, maybe_i_size;
193         int ret;
194 
195         _enter("{%llx:%llu},{%lx}",
196                vnode->fid.vid, vnode->fid.vnode, page->index);
197 
198         maybe_i_size = pos + copied;
199 
200         i_size = i_size_read(&vnode->vfs_inode);
201         if (maybe_i_size > i_size) {
202                 spin_lock(&vnode->wb_lock);
203                 i_size = i_size_read(&vnode->vfs_inode);
204                 if (maybe_i_size > i_size)
205                         i_size_write(&vnode->vfs_inode, maybe_i_size);
206                 spin_unlock(&vnode->wb_lock);
207         }
208 
209         if (!PageUptodate(page)) {
210                 if (copied < len) {
211                         /* Try and load any missing data from the server.  The
212                          * unmarshalling routine will take care of clearing any
213                          * bits that are beyond the EOF.
214                          */
215                         ret = afs_fill_page(vnode, key, pos + copied,
216                                             len - copied, page);
217                         if (ret < 0)
218                                 goto out;
219                 }
220                 SetPageUptodate(page);
221         }
222 
223         set_page_dirty(page);
224         if (PageDirty(page))
225                 _debug("dirtied");
226         ret = copied;
227 
228 out:
229         unlock_page(page);
230         put_page(page);
231         return ret;
232 }
233 
234 /*
235  * kill all the pages in the given range
236  */
237 static void afs_kill_pages(struct address_space *mapping,
238                            pgoff_t first, pgoff_t last)
239 {
240         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
241         struct pagevec pv;
242         unsigned count, loop;
243 
244         _enter("{%llx:%llu},%lx-%lx",
245                vnode->fid.vid, vnode->fid.vnode, first, last);
246 
247         pagevec_init(&pv);
248 
249         do {
250                 _debug("kill %lx-%lx", first, last);
251 
252                 count = last - first + 1;
253                 if (count > PAGEVEC_SIZE)
254                         count = PAGEVEC_SIZE;
255                 pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
256                 ASSERTCMP(pv.nr, ==, count);
257 
258                 for (loop = 0; loop < count; loop++) {
259                         struct page *page = pv.pages[loop];
260                         ClearPageUptodate(page);
261                         SetPageError(page);
262                         end_page_writeback(page);
263                         if (page->index >= first)
264                                 first = page->index + 1;
265                         lock_page(page);
266                         generic_error_remove_page(mapping, page);
267                 }
268 
269                 __pagevec_release(&pv);
270         } while (first <= last);
271 
272         _leave("");
273 }
274 
275 /*
276  * Redirty all the pages in a given range.
277  */
278 static void afs_redirty_pages(struct writeback_control *wbc,
279                               struct address_space *mapping,
280                               pgoff_t first, pgoff_t last)
281 {
282         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
283         struct pagevec pv;
284         unsigned count, loop;
285 
286         _enter("{%llx:%llu},%lx-%lx",
287                vnode->fid.vid, vnode->fid.vnode, first, last);
288 
289         pagevec_init(&pv);
290 
291         do {
292                 _debug("redirty %lx-%lx", first, last);
293 
294                 count = last - first + 1;
295                 if (count > PAGEVEC_SIZE)
296                         count = PAGEVEC_SIZE;
297                 pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
298                 ASSERTCMP(pv.nr, ==, count);
299 
300                 for (loop = 0; loop < count; loop++) {
301                         struct page *page = pv.pages[loop];
302 
303                         redirty_page_for_writepage(wbc, page);
304                         end_page_writeback(page);
305                         if (page->index >= first)
306                                 first = page->index + 1;
307                 }
308 
309                 __pagevec_release(&pv);
310         } while (first <= last);
311 
312         _leave("");
313 }
314 
315 /*
316  * write to a file
317  */
318 static int afs_store_data(struct address_space *mapping,
319                           pgoff_t first, pgoff_t last,
320                           unsigned offset, unsigned to)
321 {
322         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
323         struct afs_fs_cursor fc;
324         struct afs_wb_key *wbk = NULL;
325         struct list_head *p;
326         int ret = -ENOKEY, ret2;
327 
328         _enter("%s{%llx:%llu.%u},%lx,%lx,%x,%x",
329                vnode->volume->name,
330                vnode->fid.vid,
331                vnode->fid.vnode,
332                vnode->fid.unique,
333                first, last, offset, to);
334 
335         spin_lock(&vnode->wb_lock);
336         p = vnode->wb_keys.next;
337 
338         /* Iterate through the list looking for a valid key to use. */
339 try_next_key:
340         while (p != &vnode->wb_keys) {
341                 wbk = list_entry(p, struct afs_wb_key, vnode_link);
342                 _debug("wbk %u", key_serial(wbk->key));
343                 ret2 = key_validate(wbk->key);
344                 if (ret2 == 0)
345                         goto found_key;
346                 if (ret == -ENOKEY)
347                         ret = ret2;
348                 p = p->next;
349         }
350 
351         spin_unlock(&vnode->wb_lock);
352         afs_put_wb_key(wbk);
353         _leave(" = %d [no keys]", ret);
354         return ret;
355 
356 found_key:
357         refcount_inc(&wbk->usage);
358         spin_unlock(&vnode->wb_lock);
359 
360         _debug("USE WB KEY %u", key_serial(wbk->key));
361 
362         ret = -ERESTARTSYS;
363         if (afs_begin_vnode_operation(&fc, vnode, wbk->key)) {
364                 while (afs_select_fileserver(&fc)) {
365                         fc.cb_break = afs_calc_vnode_cb_break(vnode);
366                         afs_fs_store_data(&fc, mapping, first, last, offset, to);
367                 }
368 
369                 afs_check_for_remote_deletion(&fc, fc.vnode);
370                 afs_vnode_commit_status(&fc, vnode, fc.cb_break);
371                 ret = afs_end_vnode_operation(&fc);
372         }
373 
374         switch (ret) {
375         case 0:
376                 afs_stat_v(vnode, n_stores);
377                 atomic_long_add((last * PAGE_SIZE + to) -
378                                 (first * PAGE_SIZE + offset),
379                                 &afs_v2net(vnode)->n_store_bytes);
380                 break;
381         case -EACCES:
382         case -EPERM:
383         case -ENOKEY:
384         case -EKEYEXPIRED:
385         case -EKEYREJECTED:
386         case -EKEYREVOKED:
387                 _debug("next");
388                 spin_lock(&vnode->wb_lock);
389                 p = wbk->vnode_link.next;
390                 afs_put_wb_key(wbk);
391                 goto try_next_key;
392         }
393 
394         afs_put_wb_key(wbk);
395         _leave(" = %d", ret);
396         return ret;
397 }
398 
399 /*
400  * Synchronously write back the locked page and any subsequent non-locked dirty
401  * pages.
402  */
403 static int afs_write_back_from_locked_page(struct address_space *mapping,
404                                            struct writeback_control *wbc,
405                                            struct page *primary_page,
406                                            pgoff_t final_page)
407 {
408         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
409         struct page *pages[8], *page;
410         unsigned long count, priv;
411         unsigned n, offset, to, f, t;
412         pgoff_t start, first, last;
413         int loop, ret;
414 
415         _enter(",%lx", primary_page->index);
416 
417         count = 1;
418         if (test_set_page_writeback(primary_page))
419                 BUG();
420 
421         /* Find all consecutive lockable dirty pages that have contiguous
422          * written regions, stopping when we find a page that is not
423          * immediately lockable, is not dirty or is missing, or we reach the
424          * end of the range.
425          */
426         start = primary_page->index;
427         priv = page_private(primary_page);
428         offset = priv & AFS_PRIV_MAX;
429         to = priv >> AFS_PRIV_SHIFT;
430         trace_afs_page_dirty(vnode, tracepoint_string("store"),
431                              primary_page->index, priv);
432 
433         WARN_ON(offset == to);
434         if (offset == to)
435                 trace_afs_page_dirty(vnode, tracepoint_string("WARN"),
436                                      primary_page->index, priv);
437 
438         if (start >= final_page ||
439             (to < PAGE_SIZE && !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)))
440                 goto no_more;
441 
442         start++;
443         do {
444                 _debug("more %lx [%lx]", start, count);
445                 n = final_page - start + 1;
446                 if (n > ARRAY_SIZE(pages))
447                         n = ARRAY_SIZE(pages);
448                 n = find_get_pages_contig(mapping, start, ARRAY_SIZE(pages), pages);
449                 _debug("fgpc %u", n);
450                 if (n == 0)
451                         goto no_more;
452                 if (pages[0]->index != start) {
453                         do {
454                                 put_page(pages[--n]);
455                         } while (n > 0);
456                         goto no_more;
457                 }
458 
459                 for (loop = 0; loop < n; loop++) {
460                         page = pages[loop];
461                         if (to != PAGE_SIZE &&
462                             !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags))
463                                 break;
464                         if (page->index > final_page)
465                                 break;
466                         if (!trylock_page(page))
467                                 break;
468                         if (!PageDirty(page) || PageWriteback(page)) {
469                                 unlock_page(page);
470                                 break;
471                         }
472 
473                         priv = page_private(page);
474                         f = priv & AFS_PRIV_MAX;
475                         t = priv >> AFS_PRIV_SHIFT;
476                         if (f != 0 &&
477                             !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)) {
478                                 unlock_page(page);
479                                 break;
480                         }
481                         to = t;
482 
483                         trace_afs_page_dirty(vnode, tracepoint_string("store+"),
484                                              page->index, priv);
485 
486                         if (!clear_page_dirty_for_io(page))
487                                 BUG();
488                         if (test_set_page_writeback(page))
489                                 BUG();
490                         unlock_page(page);
491                         put_page(page);
492                 }
493                 count += loop;
494                 if (loop < n) {
495                         for (; loop < n; loop++)
496                                 put_page(pages[loop]);
497                         goto no_more;
498                 }
499 
500                 start += loop;
501         } while (start <= final_page && count < 65536);
502 
503 no_more:
504         /* We now have a contiguous set of dirty pages, each with writeback
505          * set; the first page is still locked at this point, but all the rest
506          * have been unlocked.
507          */
508         unlock_page(primary_page);
509 
510         first = primary_page->index;
511         last = first + count - 1;
512 
513         _debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
514 
515         ret = afs_store_data(mapping, first, last, offset, to);
516         switch (ret) {
517         case 0:
518                 ret = count;
519                 break;
520 
521         default:
522                 pr_notice("kAFS: Unexpected error from FS.StoreData %d\n", ret);
523                 /* Fall through */
524         case -EACCES:
525         case -EPERM:
526         case -ENOKEY:
527         case -EKEYEXPIRED:
528         case -EKEYREJECTED:
529         case -EKEYREVOKED:
530                 afs_redirty_pages(wbc, mapping, first, last);
531                 mapping_set_error(mapping, ret);
532                 break;
533 
534         case -EDQUOT:
535         case -ENOSPC:
536                 afs_redirty_pages(wbc, mapping, first, last);
537                 mapping_set_error(mapping, -ENOSPC);
538                 break;
539 
540         case -EROFS:
541         case -EIO:
542         case -EREMOTEIO:
543         case -EFBIG:
544         case -ENOENT:
545         case -ENOMEDIUM:
546         case -ENXIO:
547                 trace_afs_file_error(vnode, ret, afs_file_error_writeback_fail);
548                 afs_kill_pages(mapping, first, last);
549                 mapping_set_error(mapping, ret);
550                 break;
551         }
552 
553         _leave(" = %d", ret);
554         return ret;
555 }
556 
557 /*
558  * write a page back to the server
559  * - the caller locked the page for us
560  */
561 int afs_writepage(struct page *page, struct writeback_control *wbc)
562 {
563         int ret;
564 
565         _enter("{%lx},", page->index);
566 
567         ret = afs_write_back_from_locked_page(page->mapping, wbc, page,
568                                               wbc->range_end >> PAGE_SHIFT);
569         if (ret < 0) {
570                 _leave(" = %d", ret);
571                 return 0;
572         }
573 
574         wbc->nr_to_write -= ret;
575 
576         _leave(" = 0");
577         return 0;
578 }
579 
580 /*
581  * write a region of pages back to the server
582  */
583 static int afs_writepages_region(struct address_space *mapping,
584                                  struct writeback_control *wbc,
585                                  pgoff_t index, pgoff_t end, pgoff_t *_next)
586 {
587         struct page *page;
588         int ret, n;
589 
590         _enter(",,%lx,%lx,", index, end);
591 
592         do {
593                 n = find_get_pages_range_tag(mapping, &index, end,
594                                         PAGECACHE_TAG_DIRTY, 1, &page);
595                 if (!n)
596                         break;
597 
598                 _debug("wback %lx", page->index);
599 
600                 /*
601                  * at this point we hold neither the i_pages lock nor the
602                  * page lock: the page may be truncated or invalidated
603                  * (changing page->mapping to NULL), or even swizzled
604                  * back from swapper_space to tmpfs file mapping
605                  */
606                 ret = lock_page_killable(page);
607                 if (ret < 0) {
608                         put_page(page);
609                         _leave(" = %d", ret);
610                         return ret;
611                 }
612 
613                 if (page->mapping != mapping || !PageDirty(page)) {
614                         unlock_page(page);
615                         put_page(page);
616                         continue;
617                 }
618 
619                 if (PageWriteback(page)) {
620                         unlock_page(page);
621                         if (wbc->sync_mode != WB_SYNC_NONE)
622                                 wait_on_page_writeback(page);
623                         put_page(page);
624                         continue;
625                 }
626 
627                 if (!clear_page_dirty_for_io(page))
628                         BUG();
629                 ret = afs_write_back_from_locked_page(mapping, wbc, page, end);
630                 put_page(page);
631                 if (ret < 0) {
632                         _leave(" = %d", ret);
633                         return ret;
634                 }
635 
636                 wbc->nr_to_write -= ret;
637 
638                 cond_resched();
639         } while (index < end && wbc->nr_to_write > 0);
640 
641         *_next = index;
642         _leave(" = 0 [%lx]", *_next);
643         return 0;
644 }
645 
646 /*
647  * write some of the pending data back to the server
648  */
649 int afs_writepages(struct address_space *mapping,
650                    struct writeback_control *wbc)
651 {
652         pgoff_t start, end, next;
653         int ret;
654 
655         _enter("");
656 
657         if (wbc->range_cyclic) {
658                 start = mapping->writeback_index;
659                 end = -1;
660                 ret = afs_writepages_region(mapping, wbc, start, end, &next);
661                 if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
662                         ret = afs_writepages_region(mapping, wbc, 0, start,
663                                                     &next);
664                 mapping->writeback_index = next;
665         } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
666                 end = (pgoff_t)(LLONG_MAX >> PAGE_SHIFT);
667                 ret = afs_writepages_region(mapping, wbc, 0, end, &next);
668                 if (wbc->nr_to_write > 0)
669                         mapping->writeback_index = next;
670         } else {
671                 start = wbc->range_start >> PAGE_SHIFT;
672                 end = wbc->range_end >> PAGE_SHIFT;
673                 ret = afs_writepages_region(mapping, wbc, start, end, &next);
674         }
675 
676         _leave(" = %d", ret);
677         return ret;
678 }
679 
680 /*
681  * completion of write to server
682  */
683 void afs_pages_written_back(struct afs_vnode *vnode, struct afs_call *call)
684 {
685         struct pagevec pv;
686         unsigned long priv;
687         unsigned count, loop;
688         pgoff_t first = call->first, last = call->last;
689 
690         _enter("{%llx:%llu},{%lx-%lx}",
691                vnode->fid.vid, vnode->fid.vnode, first, last);
692 
693         pagevec_init(&pv);
694 
695         do {
696                 _debug("done %lx-%lx", first, last);
697 
698                 count = last - first + 1;
699                 if (count > PAGEVEC_SIZE)
700                         count = PAGEVEC_SIZE;
701                 pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
702                                               first, count, pv.pages);
703                 ASSERTCMP(pv.nr, ==, count);
704 
705                 for (loop = 0; loop < count; loop++) {
706                         priv = page_private(pv.pages[loop]);
707                         trace_afs_page_dirty(vnode, tracepoint_string("clear"),
708                                              pv.pages[loop]->index, priv);
709                         set_page_private(pv.pages[loop], 0);
710                         end_page_writeback(pv.pages[loop]);
711                 }
712                 first += count;
713                 __pagevec_release(&pv);
714         } while (first <= last);
715 
716         afs_prune_wb_keys(vnode);
717         _leave("");
718 }
719 
720 /*
721  * write to an AFS file
722  */
723 ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
724 {
725         struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
726         ssize_t result;
727         size_t count = iov_iter_count(from);
728 
729         _enter("{%llx:%llu},{%zu},",
730                vnode->fid.vid, vnode->fid.vnode, count);
731 
732         if (IS_SWAPFILE(&vnode->vfs_inode)) {
733                 printk(KERN_INFO
734                        "AFS: Attempt to write to active swap file!\n");
735                 return -EBUSY;
736         }
737 
738         if (!count)
739                 return 0;
740 
741         result = generic_file_write_iter(iocb, from);
742 
743         _leave(" = %zd", result);
744         return result;
745 }
746 
747 /*
748  * flush any dirty pages for this process, and check for write errors.
749  * - the return status from this call provides a reliable indication of
750  *   whether any write errors occurred for this process.
751  */
752 int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
753 {
754         struct inode *inode = file_inode(file);
755         struct afs_vnode *vnode = AFS_FS_I(inode);
756 
757         _enter("{%llx:%llu},{n=%pD},%d",
758                vnode->fid.vid, vnode->fid.vnode, file,
759                datasync);
760 
761         return file_write_and_wait_range(file, start, end);
762 }
763 
764 /*
765  * notification that a previously read-only page is about to become writable
766  * - if it returns an error, the caller will deliver a bus error signal
767  */
768 vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
769 {
770         struct file *file = vmf->vma->vm_file;
771         struct inode *inode = file_inode(file);
772         struct afs_vnode *vnode = AFS_FS_I(inode);
773         unsigned long priv;
774 
775         _enter("{{%llx:%llu}},{%lx}",
776                vnode->fid.vid, vnode->fid.vnode, vmf->page->index);
777 
778         sb_start_pagefault(inode->i_sb);
779 
780         /* Wait for the page to be written to the cache before we allow it to
781          * be modified.  We then assume the entire page will need writing back.
782          */
783 #ifdef CONFIG_AFS_FSCACHE
784         fscache_wait_on_page_write(vnode->cache, vmf->page);
785 #endif
786 
787         if (PageWriteback(vmf->page) &&
788             wait_on_page_bit_killable(vmf->page, PG_writeback) < 0)
789                 return VM_FAULT_RETRY;
790 
791         if (lock_page_killable(vmf->page) < 0)
792                 return VM_FAULT_RETRY;
793 
794         /* We mustn't change page->private until writeback is complete as that
795          * details the portion of the page we need to write back and we might
796          * need to redirty the page if there's a problem.
797          */
798         wait_on_page_writeback(vmf->page);
799 
800         priv = (unsigned long)PAGE_SIZE << AFS_PRIV_SHIFT; /* To */
801         priv |= 0; /* From */
802         trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"),
803                              vmf->page->index, priv);
804         SetPagePrivate(vmf->page);
805         set_page_private(vmf->page, priv);
806 
807         sb_end_pagefault(inode->i_sb);
808         return VM_FAULT_LOCKED;
809 }
810 
811 /*
812  * Prune the keys cached for writeback.  The caller must hold vnode->wb_lock.
813  */
814 void afs_prune_wb_keys(struct afs_vnode *vnode)
815 {
816         LIST_HEAD(graveyard);
817         struct afs_wb_key *wbk, *tmp;
818 
819         /* Discard unused keys */
820         spin_lock(&vnode->wb_lock);
821 
822         if (!mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
823             !mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_DIRTY)) {
824                 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
825                         if (refcount_read(&wbk->usage) == 1)
826                                 list_move(&wbk->vnode_link, &graveyard);
827                 }
828         }
829 
830         spin_unlock(&vnode->wb_lock);
831 
832         while (!list_empty(&graveyard)) {
833                 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
834                 list_del(&wbk->vnode_link);
835                 afs_put_wb_key(wbk);
836         }
837 }
838 
839 /*
840  * Clean up a page during invalidation.
841  */
842 int afs_launder_page(struct page *page)
843 {
844         struct address_space *mapping = page->mapping;
845         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
846         unsigned long priv;
847         unsigned int f, t;
848         int ret = 0;
849 
850         _enter("{%lx}", page->index);
851 
852         priv = page_private(page);
853         if (clear_page_dirty_for_io(page)) {
854                 f = 0;
855                 t = PAGE_SIZE;
856                 if (PagePrivate(page)) {
857                         f = priv & AFS_PRIV_MAX;
858                         t = priv >> AFS_PRIV_SHIFT;
859                 }
860 
861                 trace_afs_page_dirty(vnode, tracepoint_string("launder"),
862                                      page->index, priv);
863                 ret = afs_store_data(mapping, page->index, page->index, t, f);
864         }
865 
866         trace_afs_page_dirty(vnode, tracepoint_string("laundered"),
867                              page->index, priv);
868         set_page_private(page, 0);
869         ClearPagePrivate(page);
870 
871 #ifdef CONFIG_AFS_FSCACHE
872         if (PageFsCache(page)) {
873                 fscache_wait_on_page_write(vnode->cache, page);
874                 fscache_uncache_page(vnode->cache, page);
875         }
876 #endif
877         return ret;
878 }
879 

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