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Linux/fs/gfs2/aops.c

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  1 /*
  2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
  3  * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
  4  *
  5  * This copyrighted material is made available to anyone wishing to use,
  6  * modify, copy, or redistribute it subject to the terms and conditions
  7  * of the GNU General Public License version 2.
  8  */
  9 
 10 #include <linux/sched.h>
 11 #include <linux/slab.h>
 12 #include <linux/spinlock.h>
 13 #include <linux/completion.h>
 14 #include <linux/buffer_head.h>
 15 #include <linux/pagemap.h>
 16 #include <linux/pagevec.h>
 17 #include <linux/mpage.h>
 18 #include <linux/fs.h>
 19 #include <linux/writeback.h>
 20 #include <linux/swap.h>
 21 #include <linux/gfs2_ondisk.h>
 22 #include <linux/backing-dev.h>
 23 #include <linux/uio.h>
 24 #include <trace/events/writeback.h>
 25 
 26 #include "gfs2.h"
 27 #include "incore.h"
 28 #include "bmap.h"
 29 #include "glock.h"
 30 #include "inode.h"
 31 #include "log.h"
 32 #include "meta_io.h"
 33 #include "quota.h"
 34 #include "trans.h"
 35 #include "rgrp.h"
 36 #include "super.h"
 37 #include "util.h"
 38 #include "glops.h"
 39 
 40 
 41 static void gfs2_page_add_databufs(struct gfs2_inode *ip, struct page *page,
 42                                    unsigned int from, unsigned int to)
 43 {
 44         struct buffer_head *head = page_buffers(page);
 45         unsigned int bsize = head->b_size;
 46         struct buffer_head *bh;
 47         unsigned int start, end;
 48 
 49         for (bh = head, start = 0; bh != head || !start;
 50              bh = bh->b_this_page, start = end) {
 51                 end = start + bsize;
 52                 if (end <= from || start >= to)
 53                         continue;
 54                 if (gfs2_is_jdata(ip))
 55                         set_buffer_uptodate(bh);
 56                 gfs2_trans_add_data(ip->i_gl, bh);
 57         }
 58 }
 59 
 60 /**
 61  * gfs2_get_block_noalloc - Fills in a buffer head with details about a block
 62  * @inode: The inode
 63  * @lblock: The block number to look up
 64  * @bh_result: The buffer head to return the result in
 65  * @create: Non-zero if we may add block to the file
 66  *
 67  * Returns: errno
 68  */
 69 
 70 static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock,
 71                                   struct buffer_head *bh_result, int create)
 72 {
 73         int error;
 74 
 75         error = gfs2_block_map(inode, lblock, bh_result, 0);
 76         if (error)
 77                 return error;
 78         if (!buffer_mapped(bh_result))
 79                 return -EIO;
 80         return 0;
 81 }
 82 
 83 static int gfs2_get_block_direct(struct inode *inode, sector_t lblock,
 84                                  struct buffer_head *bh_result, int create)
 85 {
 86         return gfs2_block_map(inode, lblock, bh_result, 0);
 87 }
 88 
 89 /**
 90  * gfs2_writepage_common - Common bits of writepage
 91  * @page: The page to be written
 92  * @wbc: The writeback control
 93  *
 94  * Returns: 1 if writepage is ok, otherwise an error code or zero if no error.
 95  */
 96 
 97 static int gfs2_writepage_common(struct page *page,
 98                                  struct writeback_control *wbc)
 99 {
100         struct inode *inode = page->mapping->host;
101         struct gfs2_inode *ip = GFS2_I(inode);
102         struct gfs2_sbd *sdp = GFS2_SB(inode);
103         loff_t i_size = i_size_read(inode);
104         pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
105         unsigned offset;
106 
107         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
108                 goto out;
109         if (current->journal_info)
110                 goto redirty;
111         /* Is the page fully outside i_size? (truncate in progress) */
112         offset = i_size & (PAGE_CACHE_SIZE-1);
113         if (page->index > end_index || (page->index == end_index && !offset)) {
114                 page->mapping->a_ops->invalidatepage(page, 0, PAGE_CACHE_SIZE);
115                 goto out;
116         }
117         return 1;
118 redirty:
119         redirty_page_for_writepage(wbc, page);
120 out:
121         unlock_page(page);
122         return 0;
123 }
124 
125 /**
126  * gfs2_writepage - Write page for writeback mappings
127  * @page: The page
128  * @wbc: The writeback control
129  *
130  */
131 
132 static int gfs2_writepage(struct page *page, struct writeback_control *wbc)
133 {
134         int ret;
135 
136         ret = gfs2_writepage_common(page, wbc);
137         if (ret <= 0)
138                 return ret;
139 
140         return nobh_writepage(page, gfs2_get_block_noalloc, wbc);
141 }
142 
143 /**
144  * __gfs2_jdata_writepage - The core of jdata writepage
145  * @page: The page to write
146  * @wbc: The writeback control
147  *
148  * This is shared between writepage and writepages and implements the
149  * core of the writepage operation. If a transaction is required then
150  * PageChecked will have been set and the transaction will have
151  * already been started before this is called.
152  */
153 
154 static int __gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
155 {
156         struct inode *inode = page->mapping->host;
157         struct gfs2_inode *ip = GFS2_I(inode);
158         struct gfs2_sbd *sdp = GFS2_SB(inode);
159 
160         if (PageChecked(page)) {
161                 ClearPageChecked(page);
162                 if (!page_has_buffers(page)) {
163                         create_empty_buffers(page, inode->i_sb->s_blocksize,
164                                              (1 << BH_Dirty)|(1 << BH_Uptodate));
165                 }
166                 gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize-1);
167         }
168         return block_write_full_page(page, gfs2_get_block_noalloc, wbc);
169 }
170 
171 /**
172  * gfs2_jdata_writepage - Write complete page
173  * @page: Page to write
174  * @wbc: The writeback control
175  *
176  * Returns: errno
177  *
178  */
179 
180 static int gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
181 {
182         struct inode *inode = page->mapping->host;
183         struct gfs2_sbd *sdp = GFS2_SB(inode);
184         int ret;
185         int done_trans = 0;
186 
187         if (PageChecked(page)) {
188                 if (wbc->sync_mode != WB_SYNC_ALL)
189                         goto out_ignore;
190                 ret = gfs2_trans_begin(sdp, RES_DINODE + 1, 0);
191                 if (ret)
192                         goto out_ignore;
193                 done_trans = 1;
194         }
195         ret = gfs2_writepage_common(page, wbc);
196         if (ret > 0)
197                 ret = __gfs2_jdata_writepage(page, wbc);
198         if (done_trans)
199                 gfs2_trans_end(sdp);
200         return ret;
201 
202 out_ignore:
203         redirty_page_for_writepage(wbc, page);
204         unlock_page(page);
205         return 0;
206 }
207 
208 /**
209  * gfs2_writepages - Write a bunch of dirty pages back to disk
210  * @mapping: The mapping to write
211  * @wbc: Write-back control
212  *
213  * Used for both ordered and writeback modes.
214  */
215 static int gfs2_writepages(struct address_space *mapping,
216                            struct writeback_control *wbc)
217 {
218         return mpage_writepages(mapping, wbc, gfs2_get_block_noalloc);
219 }
220 
221 /**
222  * gfs2_write_jdata_pagevec - Write back a pagevec's worth of pages
223  * @mapping: The mapping
224  * @wbc: The writeback control
225  * @pvec: The vector of pages
226  * @nr_pages: The number of pages to write
227  * @end: End position
228  * @done_index: Page index
229  *
230  * Returns: non-zero if loop should terminate, zero otherwise
231  */
232 
233 static int gfs2_write_jdata_pagevec(struct address_space *mapping,
234                                     struct writeback_control *wbc,
235                                     struct pagevec *pvec,
236                                     int nr_pages, pgoff_t end,
237                                     pgoff_t *done_index)
238 {
239         struct inode *inode = mapping->host;
240         struct gfs2_sbd *sdp = GFS2_SB(inode);
241         unsigned nrblocks = nr_pages * (PAGE_CACHE_SIZE/inode->i_sb->s_blocksize);
242         int i;
243         int ret;
244 
245         ret = gfs2_trans_begin(sdp, nrblocks, nrblocks);
246         if (ret < 0)
247                 return ret;
248 
249         for(i = 0; i < nr_pages; i++) {
250                 struct page *page = pvec->pages[i];
251 
252                 /*
253                  * At this point, the page may be truncated or
254                  * invalidated (changing page->mapping to NULL), or
255                  * even swizzled back from swapper_space to tmpfs file
256                  * mapping. However, page->index will not change
257                  * because we have a reference on the page.
258                  */
259                 if (page->index > end) {
260                         /*
261                          * can't be range_cyclic (1st pass) because
262                          * end == -1 in that case.
263                          */
264                         ret = 1;
265                         break;
266                 }
267 
268                 *done_index = page->index;
269 
270                 lock_page(page);
271 
272                 if (unlikely(page->mapping != mapping)) {
273 continue_unlock:
274                         unlock_page(page);
275                         continue;
276                 }
277 
278                 if (!PageDirty(page)) {
279                         /* someone wrote it for us */
280                         goto continue_unlock;
281                 }
282 
283                 if (PageWriteback(page)) {
284                         if (wbc->sync_mode != WB_SYNC_NONE)
285                                 wait_on_page_writeback(page);
286                         else
287                                 goto continue_unlock;
288                 }
289 
290                 BUG_ON(PageWriteback(page));
291                 if (!clear_page_dirty_for_io(page))
292                         goto continue_unlock;
293 
294                 trace_wbc_writepage(wbc, inode_to_bdi(inode));
295 
296                 ret = __gfs2_jdata_writepage(page, wbc);
297                 if (unlikely(ret)) {
298                         if (ret == AOP_WRITEPAGE_ACTIVATE) {
299                                 unlock_page(page);
300                                 ret = 0;
301                         } else {
302 
303                                 /*
304                                  * done_index is set past this page,
305                                  * so media errors will not choke
306                                  * background writeout for the entire
307                                  * file. This has consequences for
308                                  * range_cyclic semantics (ie. it may
309                                  * not be suitable for data integrity
310                                  * writeout).
311                                  */
312                                 *done_index = page->index + 1;
313                                 ret = 1;
314                                 break;
315                         }
316                 }
317 
318                 /*
319                  * We stop writing back only if we are not doing
320                  * integrity sync. In case of integrity sync we have to
321                  * keep going until we have written all the pages
322                  * we tagged for writeback prior to entering this loop.
323                  */
324                 if (--wbc->nr_to_write <= 0 && wbc->sync_mode == WB_SYNC_NONE) {
325                         ret = 1;
326                         break;
327                 }
328 
329         }
330         gfs2_trans_end(sdp);
331         return ret;
332 }
333 
334 /**
335  * gfs2_write_cache_jdata - Like write_cache_pages but different
336  * @mapping: The mapping to write
337  * @wbc: The writeback control
338  *
339  * The reason that we use our own function here is that we need to
340  * start transactions before we grab page locks. This allows us
341  * to get the ordering right.
342  */
343 
344 static int gfs2_write_cache_jdata(struct address_space *mapping,
345                                   struct writeback_control *wbc)
346 {
347         int ret = 0;
348         int done = 0;
349         struct pagevec pvec;
350         int nr_pages;
351         pgoff_t uninitialized_var(writeback_index);
352         pgoff_t index;
353         pgoff_t end;
354         pgoff_t done_index;
355         int cycled;
356         int range_whole = 0;
357         int tag;
358 
359         pagevec_init(&pvec, 0);
360         if (wbc->range_cyclic) {
361                 writeback_index = mapping->writeback_index; /* prev offset */
362                 index = writeback_index;
363                 if (index == 0)
364                         cycled = 1;
365                 else
366                         cycled = 0;
367                 end = -1;
368         } else {
369                 index = wbc->range_start >> PAGE_CACHE_SHIFT;
370                 end = wbc->range_end >> PAGE_CACHE_SHIFT;
371                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
372                         range_whole = 1;
373                 cycled = 1; /* ignore range_cyclic tests */
374         }
375         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
376                 tag = PAGECACHE_TAG_TOWRITE;
377         else
378                 tag = PAGECACHE_TAG_DIRTY;
379 
380 retry:
381         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
382                 tag_pages_for_writeback(mapping, index, end);
383         done_index = index;
384         while (!done && (index <= end)) {
385                 nr_pages = pagevec_lookup_tag(&pvec, mapping, &index, tag,
386                               min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1);
387                 if (nr_pages == 0)
388                         break;
389 
390                 ret = gfs2_write_jdata_pagevec(mapping, wbc, &pvec, nr_pages, end, &done_index);
391                 if (ret)
392                         done = 1;
393                 if (ret > 0)
394                         ret = 0;
395                 pagevec_release(&pvec);
396                 cond_resched();
397         }
398 
399         if (!cycled && !done) {
400                 /*
401                  * range_cyclic:
402                  * We hit the last page and there is more work to be done: wrap
403                  * back to the start of the file
404                  */
405                 cycled = 1;
406                 index = 0;
407                 end = writeback_index - 1;
408                 goto retry;
409         }
410 
411         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
412                 mapping->writeback_index = done_index;
413 
414         return ret;
415 }
416 
417 
418 /**
419  * gfs2_jdata_writepages - Write a bunch of dirty pages back to disk
420  * @mapping: The mapping to write
421  * @wbc: The writeback control
422  * 
423  */
424 
425 static int gfs2_jdata_writepages(struct address_space *mapping,
426                                  struct writeback_control *wbc)
427 {
428         struct gfs2_inode *ip = GFS2_I(mapping->host);
429         struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
430         int ret;
431 
432         ret = gfs2_write_cache_jdata(mapping, wbc);
433         if (ret == 0 && wbc->sync_mode == WB_SYNC_ALL) {
434                 gfs2_log_flush(sdp, ip->i_gl, NORMAL_FLUSH);
435                 ret = gfs2_write_cache_jdata(mapping, wbc);
436         }
437         return ret;
438 }
439 
440 /**
441  * stuffed_readpage - Fill in a Linux page with stuffed file data
442  * @ip: the inode
443  * @page: the page
444  *
445  * Returns: errno
446  */
447 
448 static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
449 {
450         struct buffer_head *dibh;
451         u64 dsize = i_size_read(&ip->i_inode);
452         void *kaddr;
453         int error;
454 
455         /*
456          * Due to the order of unstuffing files and ->fault(), we can be
457          * asked for a zero page in the case of a stuffed file being extended,
458          * so we need to supply one here. It doesn't happen often.
459          */
460         if (unlikely(page->index)) {
461                 zero_user(page, 0, PAGE_CACHE_SIZE);
462                 SetPageUptodate(page);
463                 return 0;
464         }
465 
466         error = gfs2_meta_inode_buffer(ip, &dibh);
467         if (error)
468                 return error;
469 
470         kaddr = kmap_atomic(page);
471         if (dsize > (dibh->b_size - sizeof(struct gfs2_dinode)))
472                 dsize = (dibh->b_size - sizeof(struct gfs2_dinode));
473         memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize);
474         memset(kaddr + dsize, 0, PAGE_CACHE_SIZE - dsize);
475         kunmap_atomic(kaddr);
476         flush_dcache_page(page);
477         brelse(dibh);
478         SetPageUptodate(page);
479 
480         return 0;
481 }
482 
483 
484 /**
485  * __gfs2_readpage - readpage
486  * @file: The file to read a page for
487  * @page: The page to read
488  *
489  * This is the core of gfs2's readpage. Its used by the internal file
490  * reading code as in that case we already hold the glock. Also its
491  * called by gfs2_readpage() once the required lock has been granted.
492  *
493  */
494 
495 static int __gfs2_readpage(void *file, struct page *page)
496 {
497         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
498         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
499         int error;
500 
501         if (gfs2_is_stuffed(ip)) {
502                 error = stuffed_readpage(ip, page);
503                 unlock_page(page);
504         } else {
505                 error = mpage_readpage(page, gfs2_block_map);
506         }
507 
508         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
509                 return -EIO;
510 
511         return error;
512 }
513 
514 /**
515  * gfs2_readpage - read a page of a file
516  * @file: The file to read
517  * @page: The page of the file
518  *
519  * This deals with the locking required. We have to unlock and
520  * relock the page in order to get the locking in the right
521  * order.
522  */
523 
524 static int gfs2_readpage(struct file *file, struct page *page)
525 {
526         struct address_space *mapping = page->mapping;
527         struct gfs2_inode *ip = GFS2_I(mapping->host);
528         struct gfs2_holder gh;
529         int error;
530 
531         unlock_page(page);
532         gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
533         error = gfs2_glock_nq(&gh);
534         if (unlikely(error))
535                 goto out;
536         error = AOP_TRUNCATED_PAGE;
537         lock_page(page);
538         if (page->mapping == mapping && !PageUptodate(page))
539                 error = __gfs2_readpage(file, page);
540         else
541                 unlock_page(page);
542         gfs2_glock_dq(&gh);
543 out:
544         gfs2_holder_uninit(&gh);
545         if (error && error != AOP_TRUNCATED_PAGE)
546                 lock_page(page);
547         return error;
548 }
549 
550 /**
551  * gfs2_internal_read - read an internal file
552  * @ip: The gfs2 inode
553  * @buf: The buffer to fill
554  * @pos: The file position
555  * @size: The amount to read
556  *
557  */
558 
559 int gfs2_internal_read(struct gfs2_inode *ip, char *buf, loff_t *pos,
560                        unsigned size)
561 {
562         struct address_space *mapping = ip->i_inode.i_mapping;
563         unsigned long index = *pos / PAGE_CACHE_SIZE;
564         unsigned offset = *pos & (PAGE_CACHE_SIZE - 1);
565         unsigned copied = 0;
566         unsigned amt;
567         struct page *page;
568         void *p;
569 
570         do {
571                 amt = size - copied;
572                 if (offset + size > PAGE_CACHE_SIZE)
573                         amt = PAGE_CACHE_SIZE - offset;
574                 page = read_cache_page(mapping, index, __gfs2_readpage, NULL);
575                 if (IS_ERR(page))
576                         return PTR_ERR(page);
577                 p = kmap_atomic(page);
578                 memcpy(buf + copied, p + offset, amt);
579                 kunmap_atomic(p);
580                 page_cache_release(page);
581                 copied += amt;
582                 index++;
583                 offset = 0;
584         } while(copied < size);
585         (*pos) += size;
586         return size;
587 }
588 
589 /**
590  * gfs2_readpages - Read a bunch of pages at once
591  * @file: The file to read from
592  * @mapping: Address space info
593  * @pages: List of pages to read
594  * @nr_pages: Number of pages to read
595  *
596  * Some notes:
597  * 1. This is only for readahead, so we can simply ignore any things
598  *    which are slightly inconvenient (such as locking conflicts between
599  *    the page lock and the glock) and return having done no I/O. Its
600  *    obviously not something we'd want to do on too regular a basis.
601  *    Any I/O we ignore at this time will be done via readpage later.
602  * 2. We don't handle stuffed files here we let readpage do the honours.
603  * 3. mpage_readpages() does most of the heavy lifting in the common case.
604  * 4. gfs2_block_map() is relied upon to set BH_Boundary in the right places.
605  */
606 
607 static int gfs2_readpages(struct file *file, struct address_space *mapping,
608                           struct list_head *pages, unsigned nr_pages)
609 {
610         struct inode *inode = mapping->host;
611         struct gfs2_inode *ip = GFS2_I(inode);
612         struct gfs2_sbd *sdp = GFS2_SB(inode);
613         struct gfs2_holder gh;
614         int ret;
615 
616         gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
617         ret = gfs2_glock_nq(&gh);
618         if (unlikely(ret))
619                 goto out_uninit;
620         if (!gfs2_is_stuffed(ip))
621                 ret = mpage_readpages(mapping, pages, nr_pages, gfs2_block_map);
622         gfs2_glock_dq(&gh);
623 out_uninit:
624         gfs2_holder_uninit(&gh);
625         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
626                 ret = -EIO;
627         return ret;
628 }
629 
630 /**
631  * gfs2_write_begin - Begin to write to a file
632  * @file: The file to write to
633  * @mapping: The mapping in which to write
634  * @pos: The file offset at which to start writing
635  * @len: Length of the write
636  * @flags: Various flags
637  * @pagep: Pointer to return the page
638  * @fsdata: Pointer to return fs data (unused by GFS2)
639  *
640  * Returns: errno
641  */
642 
643 static int gfs2_write_begin(struct file *file, struct address_space *mapping,
644                             loff_t pos, unsigned len, unsigned flags,
645                             struct page **pagep, void **fsdata)
646 {
647         struct gfs2_inode *ip = GFS2_I(mapping->host);
648         struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
649         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
650         unsigned int data_blocks = 0, ind_blocks = 0, rblocks;
651         unsigned requested = 0;
652         int alloc_required;
653         int error = 0;
654         pgoff_t index = pos >> PAGE_CACHE_SHIFT;
655         unsigned from = pos & (PAGE_CACHE_SIZE - 1);
656         struct page *page;
657 
658         gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh);
659         error = gfs2_glock_nq(&ip->i_gh);
660         if (unlikely(error))
661                 goto out_uninit;
662         if (&ip->i_inode == sdp->sd_rindex) {
663                 error = gfs2_glock_nq_init(m_ip->i_gl, LM_ST_EXCLUSIVE,
664                                            GL_NOCACHE, &m_ip->i_gh);
665                 if (unlikely(error)) {
666                         gfs2_glock_dq(&ip->i_gh);
667                         goto out_uninit;
668                 }
669         }
670 
671         alloc_required = gfs2_write_alloc_required(ip, pos, len);
672 
673         if (alloc_required || gfs2_is_jdata(ip))
674                 gfs2_write_calc_reserv(ip, len, &data_blocks, &ind_blocks);
675 
676         if (alloc_required) {
677                 struct gfs2_alloc_parms ap = { .aflags = 0, };
678                 requested = data_blocks + ind_blocks;
679                 ap.target = requested;
680                 error = gfs2_quota_lock_check(ip, &ap);
681                 if (error)
682                         goto out_unlock;
683 
684                 error = gfs2_inplace_reserve(ip, &ap);
685                 if (error)
686                         goto out_qunlock;
687         }
688 
689         rblocks = RES_DINODE + ind_blocks;
690         if (gfs2_is_jdata(ip))
691                 rblocks += data_blocks ? data_blocks : 1;
692         if (ind_blocks || data_blocks)
693                 rblocks += RES_STATFS + RES_QUOTA;
694         if (&ip->i_inode == sdp->sd_rindex)
695                 rblocks += 2 * RES_STATFS;
696         if (alloc_required)
697                 rblocks += gfs2_rg_blocks(ip, requested);
698 
699         error = gfs2_trans_begin(sdp, rblocks,
700                                  PAGE_CACHE_SIZE/sdp->sd_sb.sb_bsize);
701         if (error)
702                 goto out_trans_fail;
703 
704         error = -ENOMEM;
705         flags |= AOP_FLAG_NOFS;
706         page = grab_cache_page_write_begin(mapping, index, flags);
707         *pagep = page;
708         if (unlikely(!page))
709                 goto out_endtrans;
710 
711         if (gfs2_is_stuffed(ip)) {
712                 error = 0;
713                 if (pos + len > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
714                         error = gfs2_unstuff_dinode(ip, page);
715                         if (error == 0)
716                                 goto prepare_write;
717                 } else if (!PageUptodate(page)) {
718                         error = stuffed_readpage(ip, page);
719                 }
720                 goto out;
721         }
722 
723 prepare_write:
724         error = __block_write_begin(page, from, len, gfs2_block_map);
725 out:
726         if (error == 0)
727                 return 0;
728 
729         unlock_page(page);
730         page_cache_release(page);
731 
732         gfs2_trans_end(sdp);
733         if (pos + len > ip->i_inode.i_size)
734                 gfs2_trim_blocks(&ip->i_inode);
735         goto out_trans_fail;
736 
737 out_endtrans:
738         gfs2_trans_end(sdp);
739 out_trans_fail:
740         if (alloc_required) {
741                 gfs2_inplace_release(ip);
742 out_qunlock:
743                 gfs2_quota_unlock(ip);
744         }
745 out_unlock:
746         if (&ip->i_inode == sdp->sd_rindex) {
747                 gfs2_glock_dq(&m_ip->i_gh);
748                 gfs2_holder_uninit(&m_ip->i_gh);
749         }
750         gfs2_glock_dq(&ip->i_gh);
751 out_uninit:
752         gfs2_holder_uninit(&ip->i_gh);
753         return error;
754 }
755 
756 /**
757  * adjust_fs_space - Adjusts the free space available due to gfs2_grow
758  * @inode: the rindex inode
759  */
760 static void adjust_fs_space(struct inode *inode)
761 {
762         struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
763         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
764         struct gfs2_inode *l_ip = GFS2_I(sdp->sd_sc_inode);
765         struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
766         struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
767         struct buffer_head *m_bh, *l_bh;
768         u64 fs_total, new_free;
769 
770         /* Total up the file system space, according to the latest rindex. */
771         fs_total = gfs2_ri_total(sdp);
772         if (gfs2_meta_inode_buffer(m_ip, &m_bh) != 0)
773                 return;
774 
775         spin_lock(&sdp->sd_statfs_spin);
776         gfs2_statfs_change_in(m_sc, m_bh->b_data +
777                               sizeof(struct gfs2_dinode));
778         if (fs_total > (m_sc->sc_total + l_sc->sc_total))
779                 new_free = fs_total - (m_sc->sc_total + l_sc->sc_total);
780         else
781                 new_free = 0;
782         spin_unlock(&sdp->sd_statfs_spin);
783         fs_warn(sdp, "File system extended by %llu blocks.\n",
784                 (unsigned long long)new_free);
785         gfs2_statfs_change(sdp, new_free, new_free, 0);
786 
787         if (gfs2_meta_inode_buffer(l_ip, &l_bh) != 0)
788                 goto out;
789         update_statfs(sdp, m_bh, l_bh);
790         brelse(l_bh);
791 out:
792         brelse(m_bh);
793 }
794 
795 /**
796  * gfs2_stuffed_write_end - Write end for stuffed files
797  * @inode: The inode
798  * @dibh: The buffer_head containing the on-disk inode
799  * @pos: The file position
800  * @len: The length of the write
801  * @copied: How much was actually copied by the VFS
802  * @page: The page
803  *
804  * This copies the data from the page into the inode block after
805  * the inode data structure itself.
806  *
807  * Returns: errno
808  */
809 static int gfs2_stuffed_write_end(struct inode *inode, struct buffer_head *dibh,
810                                   loff_t pos, unsigned len, unsigned copied,
811                                   struct page *page)
812 {
813         struct gfs2_inode *ip = GFS2_I(inode);
814         struct gfs2_sbd *sdp = GFS2_SB(inode);
815         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
816         u64 to = pos + copied;
817         void *kaddr;
818         unsigned char *buf = dibh->b_data + sizeof(struct gfs2_dinode);
819 
820         BUG_ON((pos + len) > (dibh->b_size - sizeof(struct gfs2_dinode)));
821         kaddr = kmap_atomic(page);
822         memcpy(buf + pos, kaddr + pos, copied);
823         memset(kaddr + pos + copied, 0, len - copied);
824         flush_dcache_page(page);
825         kunmap_atomic(kaddr);
826 
827         if (!PageUptodate(page))
828                 SetPageUptodate(page);
829         unlock_page(page);
830         page_cache_release(page);
831 
832         if (copied) {
833                 if (inode->i_size < to)
834                         i_size_write(inode, to);
835                 mark_inode_dirty(inode);
836         }
837 
838         if (inode == sdp->sd_rindex) {
839                 adjust_fs_space(inode);
840                 sdp->sd_rindex_uptodate = 0;
841         }
842 
843         brelse(dibh);
844         gfs2_trans_end(sdp);
845         if (inode == sdp->sd_rindex) {
846                 gfs2_glock_dq(&m_ip->i_gh);
847                 gfs2_holder_uninit(&m_ip->i_gh);
848         }
849         gfs2_glock_dq(&ip->i_gh);
850         gfs2_holder_uninit(&ip->i_gh);
851         return copied;
852 }
853 
854 /**
855  * gfs2_write_end
856  * @file: The file to write to
857  * @mapping: The address space to write to
858  * @pos: The file position
859  * @len: The length of the data
860  * @copied: How much was actually copied by the VFS
861  * @page: The page that has been written
862  * @fsdata: The fsdata (unused in GFS2)
863  *
864  * The main write_end function for GFS2. We have a separate one for
865  * stuffed files as they are slightly different, otherwise we just
866  * put our locking around the VFS provided functions.
867  *
868  * Returns: errno
869  */
870 
871 static int gfs2_write_end(struct file *file, struct address_space *mapping,
872                           loff_t pos, unsigned len, unsigned copied,
873                           struct page *page, void *fsdata)
874 {
875         struct inode *inode = page->mapping->host;
876         struct gfs2_inode *ip = GFS2_I(inode);
877         struct gfs2_sbd *sdp = GFS2_SB(inode);
878         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
879         struct buffer_head *dibh;
880         unsigned int from = pos & (PAGE_CACHE_SIZE - 1);
881         unsigned int to = from + len;
882         int ret;
883         struct gfs2_trans *tr = current->journal_info;
884         BUG_ON(!tr);
885 
886         BUG_ON(gfs2_glock_is_locked_by_me(ip->i_gl) == NULL);
887 
888         ret = gfs2_meta_inode_buffer(ip, &dibh);
889         if (unlikely(ret)) {
890                 unlock_page(page);
891                 page_cache_release(page);
892                 goto failed;
893         }
894 
895         if (gfs2_is_stuffed(ip))
896                 return gfs2_stuffed_write_end(inode, dibh, pos, len, copied, page);
897 
898         if (!gfs2_is_writeback(ip))
899                 gfs2_page_add_databufs(ip, page, from, to);
900 
901         ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
902         if (tr->tr_num_buf_new)
903                 __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
904         else
905                 gfs2_trans_add_meta(ip->i_gl, dibh);
906 
907 
908         if (inode == sdp->sd_rindex) {
909                 adjust_fs_space(inode);
910                 sdp->sd_rindex_uptodate = 0;
911         }
912 
913         brelse(dibh);
914 failed:
915         gfs2_trans_end(sdp);
916         gfs2_inplace_release(ip);
917         if (ip->i_qadata && ip->i_qadata->qa_qd_num)
918                 gfs2_quota_unlock(ip);
919         if (inode == sdp->sd_rindex) {
920                 gfs2_glock_dq(&m_ip->i_gh);
921                 gfs2_holder_uninit(&m_ip->i_gh);
922         }
923         gfs2_glock_dq(&ip->i_gh);
924         gfs2_holder_uninit(&ip->i_gh);
925         return ret;
926 }
927 
928 /**
929  * gfs2_set_page_dirty - Page dirtying function
930  * @page: The page to dirty
931  *
932  * Returns: 1 if it dirtyed the page, or 0 otherwise
933  */
934  
935 static int gfs2_set_page_dirty(struct page *page)
936 {
937         SetPageChecked(page);
938         return __set_page_dirty_buffers(page);
939 }
940 
941 /**
942  * gfs2_bmap - Block map function
943  * @mapping: Address space info
944  * @lblock: The block to map
945  *
946  * Returns: The disk address for the block or 0 on hole or error
947  */
948 
949 static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
950 {
951         struct gfs2_inode *ip = GFS2_I(mapping->host);
952         struct gfs2_holder i_gh;
953         sector_t dblock = 0;
954         int error;
955 
956         error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
957         if (error)
958                 return 0;
959 
960         if (!gfs2_is_stuffed(ip))
961                 dblock = generic_block_bmap(mapping, lblock, gfs2_block_map);
962 
963         gfs2_glock_dq_uninit(&i_gh);
964 
965         return dblock;
966 }
967 
968 static void gfs2_discard(struct gfs2_sbd *sdp, struct buffer_head *bh)
969 {
970         struct gfs2_bufdata *bd;
971 
972         lock_buffer(bh);
973         gfs2_log_lock(sdp);
974         clear_buffer_dirty(bh);
975         bd = bh->b_private;
976         if (bd) {
977                 if (!list_empty(&bd->bd_list) && !buffer_pinned(bh))
978                         list_del_init(&bd->bd_list);
979                 else
980                         gfs2_remove_from_journal(bh, current->journal_info, 0);
981         }
982         bh->b_bdev = NULL;
983         clear_buffer_mapped(bh);
984         clear_buffer_req(bh);
985         clear_buffer_new(bh);
986         gfs2_log_unlock(sdp);
987         unlock_buffer(bh);
988 }
989 
990 static void gfs2_invalidatepage(struct page *page, unsigned int offset,
991                                 unsigned int length)
992 {
993         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
994         unsigned int stop = offset + length;
995         int partial_page = (offset || length < PAGE_CACHE_SIZE);
996         struct buffer_head *bh, *head;
997         unsigned long pos = 0;
998 
999         BUG_ON(!PageLocked(page));
1000         if (!partial_page)
1001                 ClearPageChecked(page);
1002         if (!page_has_buffers(page))
1003                 goto out;
1004 
1005         bh = head = page_buffers(page);
1006         do {
1007                 if (pos + bh->b_size > stop)
1008                         return;
1009 
1010                 if (offset <= pos)
1011                         gfs2_discard(sdp, bh);
1012                 pos += bh->b_size;
1013                 bh = bh->b_this_page;
1014         } while (bh != head);
1015 out:
1016         if (!partial_page)
1017                 try_to_release_page(page, 0);
1018 }
1019 
1020 /**
1021  * gfs2_ok_for_dio - check that dio is valid on this file
1022  * @ip: The inode
1023  * @offset: The offset at which we are reading or writing
1024  *
1025  * Returns: 0 (to ignore the i/o request and thus fall back to buffered i/o)
1026  *          1 (to accept the i/o request)
1027  */
1028 static int gfs2_ok_for_dio(struct gfs2_inode *ip, loff_t offset)
1029 {
1030         /*
1031          * Should we return an error here? I can't see that O_DIRECT for
1032          * a stuffed file makes any sense. For now we'll silently fall
1033          * back to buffered I/O
1034          */
1035         if (gfs2_is_stuffed(ip))
1036                 return 0;
1037 
1038         if (offset >= i_size_read(&ip->i_inode))
1039                 return 0;
1040         return 1;
1041 }
1042 
1043 
1044 
1045 static ssize_t gfs2_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
1046                               loff_t offset)
1047 {
1048         struct file *file = iocb->ki_filp;
1049         struct inode *inode = file->f_mapping->host;
1050         struct address_space *mapping = inode->i_mapping;
1051         struct gfs2_inode *ip = GFS2_I(inode);
1052         struct gfs2_holder gh;
1053         int rv;
1054 
1055         /*
1056          * Deferred lock, even if its a write, since we do no allocation
1057          * on this path. All we need change is atime, and this lock mode
1058          * ensures that other nodes have flushed their buffered read caches
1059          * (i.e. their page cache entries for this inode). We do not,
1060          * unfortunately have the option of only flushing a range like
1061          * the VFS does.
1062          */
1063         gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, 0, &gh);
1064         rv = gfs2_glock_nq(&gh);
1065         if (rv)
1066                 return rv;
1067         rv = gfs2_ok_for_dio(ip, offset);
1068         if (rv != 1)
1069                 goto out; /* dio not valid, fall back to buffered i/o */
1070 
1071         /*
1072          * Now since we are holding a deferred (CW) lock at this point, you
1073          * might be wondering why this is ever needed. There is a case however
1074          * where we've granted a deferred local lock against a cached exclusive
1075          * glock. That is ok provided all granted local locks are deferred, but
1076          * it also means that it is possible to encounter pages which are
1077          * cached and possibly also mapped. So here we check for that and sort
1078          * them out ahead of the dio. The glock state machine will take care of
1079          * everything else.
1080          *
1081          * If in fact the cached glock state (gl->gl_state) is deferred (CW) in
1082          * the first place, mapping->nr_pages will always be zero.
1083          */
1084         if (mapping->nrpages) {
1085                 loff_t lstart = offset & (PAGE_CACHE_SIZE - 1);
1086                 loff_t len = iov_iter_count(iter);
1087                 loff_t end = PAGE_ALIGN(offset + len) - 1;
1088 
1089                 rv = 0;
1090                 if (len == 0)
1091                         goto out;
1092                 if (test_and_clear_bit(GIF_SW_PAGED, &ip->i_flags))
1093                         unmap_shared_mapping_range(ip->i_inode.i_mapping, offset, len);
1094                 rv = filemap_write_and_wait_range(mapping, lstart, end);
1095                 if (rv)
1096                         goto out;
1097                 if (iov_iter_rw(iter) == WRITE)
1098                         truncate_inode_pages_range(mapping, lstart, end);
1099         }
1100 
1101         rv = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, iter,
1102                                   offset, gfs2_get_block_direct, NULL, NULL, 0);
1103 out:
1104         gfs2_glock_dq(&gh);
1105         gfs2_holder_uninit(&gh);
1106         return rv;
1107 }
1108 
1109 /**
1110  * gfs2_releasepage - free the metadata associated with a page
1111  * @page: the page that's being released
1112  * @gfp_mask: passed from Linux VFS, ignored by us
1113  *
1114  * Call try_to_free_buffers() if the buffers in this page can be
1115  * released.
1116  *
1117  * Returns: 0
1118  */
1119 
1120 int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
1121 {
1122         struct address_space *mapping = page->mapping;
1123         struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
1124         struct buffer_head *bh, *head;
1125         struct gfs2_bufdata *bd;
1126 
1127         if (!page_has_buffers(page))
1128                 return 0;
1129 
1130         gfs2_log_lock(sdp);
1131         spin_lock(&sdp->sd_ail_lock);
1132         head = bh = page_buffers(page);
1133         do {
1134                 if (atomic_read(&bh->b_count))
1135                         goto cannot_release;
1136                 bd = bh->b_private;
1137                 if (bd && bd->bd_tr)
1138                         goto cannot_release;
1139                 if (buffer_pinned(bh) || buffer_dirty(bh))
1140                         goto not_possible;
1141                 bh = bh->b_this_page;
1142         } while(bh != head);
1143         spin_unlock(&sdp->sd_ail_lock);
1144 
1145         head = bh = page_buffers(page);
1146         do {
1147                 bd = bh->b_private;
1148                 if (bd) {
1149                         gfs2_assert_warn(sdp, bd->bd_bh == bh);
1150                         if (!list_empty(&bd->bd_list))
1151                                 list_del_init(&bd->bd_list);
1152                         bd->bd_bh = NULL;
1153                         bh->b_private = NULL;
1154                         kmem_cache_free(gfs2_bufdata_cachep, bd);
1155                 }
1156 
1157                 bh = bh->b_this_page;
1158         } while (bh != head);
1159         gfs2_log_unlock(sdp);
1160 
1161         return try_to_free_buffers(page);
1162 
1163 not_possible: /* Should never happen */
1164         WARN_ON(buffer_dirty(bh));
1165         WARN_ON(buffer_pinned(bh));
1166 cannot_release:
1167         spin_unlock(&sdp->sd_ail_lock);
1168         gfs2_log_unlock(sdp);
1169         return 0;
1170 }
1171 
1172 static const struct address_space_operations gfs2_writeback_aops = {
1173         .writepage = gfs2_writepage,
1174         .writepages = gfs2_writepages,
1175         .readpage = gfs2_readpage,
1176         .readpages = gfs2_readpages,
1177         .write_begin = gfs2_write_begin,
1178         .write_end = gfs2_write_end,
1179         .bmap = gfs2_bmap,
1180         .invalidatepage = gfs2_invalidatepage,
1181         .releasepage = gfs2_releasepage,
1182         .direct_IO = gfs2_direct_IO,
1183         .migratepage = buffer_migrate_page,
1184         .is_partially_uptodate = block_is_partially_uptodate,
1185         .error_remove_page = generic_error_remove_page,
1186 };
1187 
1188 static const struct address_space_operations gfs2_ordered_aops = {
1189         .writepage = gfs2_writepage,
1190         .writepages = gfs2_writepages,
1191         .readpage = gfs2_readpage,
1192         .readpages = gfs2_readpages,
1193         .write_begin = gfs2_write_begin,
1194         .write_end = gfs2_write_end,
1195         .set_page_dirty = gfs2_set_page_dirty,
1196         .bmap = gfs2_bmap,
1197         .invalidatepage = gfs2_invalidatepage,
1198         .releasepage = gfs2_releasepage,
1199         .direct_IO = gfs2_direct_IO,
1200         .migratepage = buffer_migrate_page,
1201         .is_partially_uptodate = block_is_partially_uptodate,
1202         .error_remove_page = generic_error_remove_page,
1203 };
1204 
1205 static const struct address_space_operations gfs2_jdata_aops = {
1206         .writepage = gfs2_jdata_writepage,
1207         .writepages = gfs2_jdata_writepages,
1208         .readpage = gfs2_readpage,
1209         .readpages = gfs2_readpages,
1210         .write_begin = gfs2_write_begin,
1211         .write_end = gfs2_write_end,
1212         .set_page_dirty = gfs2_set_page_dirty,
1213         .bmap = gfs2_bmap,
1214         .invalidatepage = gfs2_invalidatepage,
1215         .releasepage = gfs2_releasepage,
1216         .is_partially_uptodate = block_is_partially_uptodate,
1217         .error_remove_page = generic_error_remove_page,
1218 };
1219 
1220 void gfs2_set_aops(struct inode *inode)
1221 {
1222         struct gfs2_inode *ip = GFS2_I(inode);
1223 
1224         if (gfs2_is_writeback(ip))
1225                 inode->i_mapping->a_ops = &gfs2_writeback_aops;
1226         else if (gfs2_is_ordered(ip))
1227                 inode->i_mapping->a_ops = &gfs2_ordered_aops;
1228         else if (gfs2_is_jdata(ip))
1229                 inode->i_mapping->a_ops = &gfs2_jdata_aops;
1230         else
1231                 BUG();
1232 }
1233 
1234 

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