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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  *
175  * Returns: errno
176  *
177  */
178 
179 static int gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
180 {
181         struct inode *inode = page->mapping->host;
182         struct gfs2_sbd *sdp = GFS2_SB(inode);
183         int ret;
184         int done_trans = 0;
185 
186         if (PageChecked(page)) {
187                 if (wbc->sync_mode != WB_SYNC_ALL)
188                         goto out_ignore;
189                 ret = gfs2_trans_begin(sdp, RES_DINODE + 1, 0);
190                 if (ret)
191                         goto out_ignore;
192                 done_trans = 1;
193         }
194         ret = gfs2_writepage_common(page, wbc);
195         if (ret > 0)
196                 ret = __gfs2_jdata_writepage(page, wbc);
197         if (done_trans)
198                 gfs2_trans_end(sdp);
199         return ret;
200 
201 out_ignore:
202         redirty_page_for_writepage(wbc, page);
203         unlock_page(page);
204         return 0;
205 }
206 
207 /**
208  * gfs2_writepages - Write a bunch of dirty pages back to disk
209  * @mapping: The mapping to write
210  * @wbc: Write-back control
211  *
212  * Used for both ordered and writeback modes.
213  */
214 static int gfs2_writepages(struct address_space *mapping,
215                            struct writeback_control *wbc)
216 {
217         return mpage_writepages(mapping, wbc, gfs2_get_block_noalloc);
218 }
219 
220 /**
221  * gfs2_write_jdata_pagevec - Write back a pagevec's worth of pages
222  * @mapping: The mapping
223  * @wbc: The writeback control
224  * @writepage: The writepage function to call for each page
225  * @pvec: The vector of pages
226  * @nr_pages: The number of pages to write
227  *
228  * Returns: non-zero if loop should terminate, zero otherwise
229  */
230 
231 static int gfs2_write_jdata_pagevec(struct address_space *mapping,
232                                     struct writeback_control *wbc,
233                                     struct pagevec *pvec,
234                                     int nr_pages, pgoff_t end,
235                                     pgoff_t *done_index)
236 {
237         struct inode *inode = mapping->host;
238         struct gfs2_sbd *sdp = GFS2_SB(inode);
239         unsigned nrblocks = nr_pages * (PAGE_CACHE_SIZE/inode->i_sb->s_blocksize);
240         int i;
241         int ret;
242 
243         ret = gfs2_trans_begin(sdp, nrblocks, nrblocks);
244         if (ret < 0)
245                 return ret;
246 
247         for(i = 0; i < nr_pages; i++) {
248                 struct page *page = pvec->pages[i];
249 
250                 /*
251                  * At this point, the page may be truncated or
252                  * invalidated (changing page->mapping to NULL), or
253                  * even swizzled back from swapper_space to tmpfs file
254                  * mapping. However, page->index will not change
255                  * because we have a reference on the page.
256                  */
257                 if (page->index > end) {
258                         /*
259                          * can't be range_cyclic (1st pass) because
260                          * end == -1 in that case.
261                          */
262                         ret = 1;
263                         break;
264                 }
265 
266                 *done_index = page->index;
267 
268                 lock_page(page);
269 
270                 if (unlikely(page->mapping != mapping)) {
271 continue_unlock:
272                         unlock_page(page);
273                         continue;
274                 }
275 
276                 if (!PageDirty(page)) {
277                         /* someone wrote it for us */
278                         goto continue_unlock;
279                 }
280 
281                 if (PageWriteback(page)) {
282                         if (wbc->sync_mode != WB_SYNC_NONE)
283                                 wait_on_page_writeback(page);
284                         else
285                                 goto continue_unlock;
286                 }
287 
288                 BUG_ON(PageWriteback(page));
289                 if (!clear_page_dirty_for_io(page))
290                         goto continue_unlock;
291 
292                 trace_wbc_writepage(wbc, inode_to_bdi(inode));
293 
294                 ret = __gfs2_jdata_writepage(page, wbc);
295                 if (unlikely(ret)) {
296                         if (ret == AOP_WRITEPAGE_ACTIVATE) {
297                                 unlock_page(page);
298                                 ret = 0;
299                         } else {
300 
301                                 /*
302                                  * done_index is set past this page,
303                                  * so media errors will not choke
304                                  * background writeout for the entire
305                                  * file. This has consequences for
306                                  * range_cyclic semantics (ie. it may
307                                  * not be suitable for data integrity
308                                  * writeout).
309                                  */
310                                 *done_index = page->index + 1;
311                                 ret = 1;
312                                 break;
313                         }
314                 }
315 
316                 /*
317                  * We stop writing back only if we are not doing
318                  * integrity sync. In case of integrity sync we have to
319                  * keep going until we have written all the pages
320                  * we tagged for writeback prior to entering this loop.
321                  */
322                 if (--wbc->nr_to_write <= 0 && wbc->sync_mode == WB_SYNC_NONE) {
323                         ret = 1;
324                         break;
325                 }
326 
327         }
328         gfs2_trans_end(sdp);
329         return ret;
330 }
331 
332 /**
333  * gfs2_write_cache_jdata - Like write_cache_pages but different
334  * @mapping: The mapping to write
335  * @wbc: The writeback control
336  * @writepage: The writepage function to call
337  * @data: The data to pass to writepage
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  *
592  * Some notes:
593  * 1. This is only for readahead, so we can simply ignore any things
594  *    which are slightly inconvenient (such as locking conflicts between
595  *    the page lock and the glock) and return having done no I/O. Its
596  *    obviously not something we'd want to do on too regular a basis.
597  *    Any I/O we ignore at this time will be done via readpage later.
598  * 2. We don't handle stuffed files here we let readpage do the honours.
599  * 3. mpage_readpages() does most of the heavy lifting in the common case.
600  * 4. gfs2_block_map() is relied upon to set BH_Boundary in the right places.
601  */
602 
603 static int gfs2_readpages(struct file *file, struct address_space *mapping,
604                           struct list_head *pages, unsigned nr_pages)
605 {
606         struct inode *inode = mapping->host;
607         struct gfs2_inode *ip = GFS2_I(inode);
608         struct gfs2_sbd *sdp = GFS2_SB(inode);
609         struct gfs2_holder gh;
610         int ret;
611 
612         gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
613         ret = gfs2_glock_nq(&gh);
614         if (unlikely(ret))
615                 goto out_uninit;
616         if (!gfs2_is_stuffed(ip))
617                 ret = mpage_readpages(mapping, pages, nr_pages, gfs2_block_map);
618         gfs2_glock_dq(&gh);
619 out_uninit:
620         gfs2_holder_uninit(&gh);
621         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
622                 ret = -EIO;
623         return ret;
624 }
625 
626 /**
627  * gfs2_write_begin - Begin to write to a file
628  * @file: The file to write to
629  * @mapping: The mapping in which to write
630  * @pos: The file offset at which to start writing
631  * @len: Length of the write
632  * @flags: Various flags
633  * @pagep: Pointer to return the page
634  * @fsdata: Pointer to return fs data (unused by GFS2)
635  *
636  * Returns: errno
637  */
638 
639 static int gfs2_write_begin(struct file *file, struct address_space *mapping,
640                             loff_t pos, unsigned len, unsigned flags,
641                             struct page **pagep, void **fsdata)
642 {
643         struct gfs2_inode *ip = GFS2_I(mapping->host);
644         struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
645         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
646         unsigned int data_blocks = 0, ind_blocks = 0, rblocks;
647         unsigned requested = 0;
648         int alloc_required;
649         int error = 0;
650         pgoff_t index = pos >> PAGE_CACHE_SHIFT;
651         unsigned from = pos & (PAGE_CACHE_SIZE - 1);
652         struct page *page;
653 
654         gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh);
655         error = gfs2_glock_nq(&ip->i_gh);
656         if (unlikely(error))
657                 goto out_uninit;
658         if (&ip->i_inode == sdp->sd_rindex) {
659                 error = gfs2_glock_nq_init(m_ip->i_gl, LM_ST_EXCLUSIVE,
660                                            GL_NOCACHE, &m_ip->i_gh);
661                 if (unlikely(error)) {
662                         gfs2_glock_dq(&ip->i_gh);
663                         goto out_uninit;
664                 }
665         }
666 
667         alloc_required = gfs2_write_alloc_required(ip, pos, len);
668 
669         if (alloc_required || gfs2_is_jdata(ip))
670                 gfs2_write_calc_reserv(ip, len, &data_blocks, &ind_blocks);
671 
672         if (alloc_required) {
673                 struct gfs2_alloc_parms ap = { .aflags = 0, };
674                 requested = data_blocks + ind_blocks;
675                 ap.target = requested;
676                 error = gfs2_quota_lock_check(ip, &ap);
677                 if (error)
678                         goto out_unlock;
679 
680                 error = gfs2_inplace_reserve(ip, &ap);
681                 if (error)
682                         goto out_qunlock;
683         }
684 
685         rblocks = RES_DINODE + ind_blocks;
686         if (gfs2_is_jdata(ip))
687                 rblocks += data_blocks ? data_blocks : 1;
688         if (ind_blocks || data_blocks)
689                 rblocks += RES_STATFS + RES_QUOTA;
690         if (&ip->i_inode == sdp->sd_rindex)
691                 rblocks += 2 * RES_STATFS;
692         if (alloc_required)
693                 rblocks += gfs2_rg_blocks(ip, requested);
694 
695         error = gfs2_trans_begin(sdp, rblocks,
696                                  PAGE_CACHE_SIZE/sdp->sd_sb.sb_bsize);
697         if (error)
698                 goto out_trans_fail;
699 
700         error = -ENOMEM;
701         flags |= AOP_FLAG_NOFS;
702         page = grab_cache_page_write_begin(mapping, index, flags);
703         *pagep = page;
704         if (unlikely(!page))
705                 goto out_endtrans;
706 
707         if (gfs2_is_stuffed(ip)) {
708                 error = 0;
709                 if (pos + len > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
710                         error = gfs2_unstuff_dinode(ip, page);
711                         if (error == 0)
712                                 goto prepare_write;
713                 } else if (!PageUptodate(page)) {
714                         error = stuffed_readpage(ip, page);
715                 }
716                 goto out;
717         }
718 
719 prepare_write:
720         error = __block_write_begin(page, from, len, gfs2_block_map);
721 out:
722         if (error == 0)
723                 return 0;
724 
725         unlock_page(page);
726         page_cache_release(page);
727 
728         gfs2_trans_end(sdp);
729         if (pos + len > ip->i_inode.i_size)
730                 gfs2_trim_blocks(&ip->i_inode);
731         goto out_trans_fail;
732 
733 out_endtrans:
734         gfs2_trans_end(sdp);
735 out_trans_fail:
736         if (alloc_required) {
737                 gfs2_inplace_release(ip);
738 out_qunlock:
739                 gfs2_quota_unlock(ip);
740         }
741 out_unlock:
742         if (&ip->i_inode == sdp->sd_rindex) {
743                 gfs2_glock_dq(&m_ip->i_gh);
744                 gfs2_holder_uninit(&m_ip->i_gh);
745         }
746         gfs2_glock_dq(&ip->i_gh);
747 out_uninit:
748         gfs2_holder_uninit(&ip->i_gh);
749         return error;
750 }
751 
752 /**
753  * adjust_fs_space - Adjusts the free space available due to gfs2_grow
754  * @inode: the rindex inode
755  */
756 static void adjust_fs_space(struct inode *inode)
757 {
758         struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
759         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
760         struct gfs2_inode *l_ip = GFS2_I(sdp->sd_sc_inode);
761         struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
762         struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
763         struct buffer_head *m_bh, *l_bh;
764         u64 fs_total, new_free;
765 
766         /* Total up the file system space, according to the latest rindex. */
767         fs_total = gfs2_ri_total(sdp);
768         if (gfs2_meta_inode_buffer(m_ip, &m_bh) != 0)
769                 return;
770 
771         spin_lock(&sdp->sd_statfs_spin);
772         gfs2_statfs_change_in(m_sc, m_bh->b_data +
773                               sizeof(struct gfs2_dinode));
774         if (fs_total > (m_sc->sc_total + l_sc->sc_total))
775                 new_free = fs_total - (m_sc->sc_total + l_sc->sc_total);
776         else
777                 new_free = 0;
778         spin_unlock(&sdp->sd_statfs_spin);
779         fs_warn(sdp, "File system extended by %llu blocks.\n",
780                 (unsigned long long)new_free);
781         gfs2_statfs_change(sdp, new_free, new_free, 0);
782 
783         if (gfs2_meta_inode_buffer(l_ip, &l_bh) != 0)
784                 goto out;
785         update_statfs(sdp, m_bh, l_bh);
786         brelse(l_bh);
787 out:
788         brelse(m_bh);
789 }
790 
791 /**
792  * gfs2_stuffed_write_end - Write end for stuffed files
793  * @inode: The inode
794  * @dibh: The buffer_head containing the on-disk inode
795  * @pos: The file position
796  * @len: The length of the write
797  * @copied: How much was actually copied by the VFS
798  * @page: The page
799  *
800  * This copies the data from the page into the inode block after
801  * the inode data structure itself.
802  *
803  * Returns: errno
804  */
805 static int gfs2_stuffed_write_end(struct inode *inode, struct buffer_head *dibh,
806                                   loff_t pos, unsigned len, unsigned copied,
807                                   struct page *page)
808 {
809         struct gfs2_inode *ip = GFS2_I(inode);
810         struct gfs2_sbd *sdp = GFS2_SB(inode);
811         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
812         u64 to = pos + copied;
813         void *kaddr;
814         unsigned char *buf = dibh->b_data + sizeof(struct gfs2_dinode);
815 
816         BUG_ON((pos + len) > (dibh->b_size - sizeof(struct gfs2_dinode)));
817         kaddr = kmap_atomic(page);
818         memcpy(buf + pos, kaddr + pos, copied);
819         memset(kaddr + pos + copied, 0, len - copied);
820         flush_dcache_page(page);
821         kunmap_atomic(kaddr);
822 
823         if (!PageUptodate(page))
824                 SetPageUptodate(page);
825         unlock_page(page);
826         page_cache_release(page);
827 
828         if (copied) {
829                 if (inode->i_size < to)
830                         i_size_write(inode, to);
831                 mark_inode_dirty(inode);
832         }
833 
834         if (inode == sdp->sd_rindex) {
835                 adjust_fs_space(inode);
836                 sdp->sd_rindex_uptodate = 0;
837         }
838 
839         brelse(dibh);
840         gfs2_trans_end(sdp);
841         if (inode == sdp->sd_rindex) {
842                 gfs2_glock_dq(&m_ip->i_gh);
843                 gfs2_holder_uninit(&m_ip->i_gh);
844         }
845         gfs2_glock_dq(&ip->i_gh);
846         gfs2_holder_uninit(&ip->i_gh);
847         return copied;
848 }
849 
850 /**
851  * gfs2_write_end
852  * @file: The file to write to
853  * @mapping: The address space to write to
854  * @pos: The file position
855  * @len: The length of the data
856  * @copied:
857  * @page: The page that has been written
858  * @fsdata: The fsdata (unused in GFS2)
859  *
860  * The main write_end function for GFS2. We have a separate one for
861  * stuffed files as they are slightly different, otherwise we just
862  * put our locking around the VFS provided functions.
863  *
864  * Returns: errno
865  */
866 
867 static int gfs2_write_end(struct file *file, struct address_space *mapping,
868                           loff_t pos, unsigned len, unsigned copied,
869                           struct page *page, void *fsdata)
870 {
871         struct inode *inode = page->mapping->host;
872         struct gfs2_inode *ip = GFS2_I(inode);
873         struct gfs2_sbd *sdp = GFS2_SB(inode);
874         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
875         struct buffer_head *dibh;
876         unsigned int from = pos & (PAGE_CACHE_SIZE - 1);
877         unsigned int to = from + len;
878         int ret;
879         struct gfs2_trans *tr = current->journal_info;
880         BUG_ON(!tr);
881 
882         BUG_ON(gfs2_glock_is_locked_by_me(ip->i_gl) == NULL);
883 
884         ret = gfs2_meta_inode_buffer(ip, &dibh);
885         if (unlikely(ret)) {
886                 unlock_page(page);
887                 page_cache_release(page);
888                 goto failed;
889         }
890 
891         if (gfs2_is_stuffed(ip))
892                 return gfs2_stuffed_write_end(inode, dibh, pos, len, copied, page);
893 
894         if (!gfs2_is_writeback(ip))
895                 gfs2_page_add_databufs(ip, page, from, to);
896 
897         ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
898         if (tr->tr_num_buf_new)
899                 __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
900         else
901                 gfs2_trans_add_meta(ip->i_gl, dibh);
902 
903 
904         if (inode == sdp->sd_rindex) {
905                 adjust_fs_space(inode);
906                 sdp->sd_rindex_uptodate = 0;
907         }
908 
909         brelse(dibh);
910 failed:
911         gfs2_trans_end(sdp);
912         gfs2_inplace_release(ip);
913         if (ip->i_res->rs_qa_qd_num)
914                 gfs2_quota_unlock(ip);
915         if (inode == sdp->sd_rindex) {
916                 gfs2_glock_dq(&m_ip->i_gh);
917                 gfs2_holder_uninit(&m_ip->i_gh);
918         }
919         gfs2_glock_dq(&ip->i_gh);
920         gfs2_holder_uninit(&ip->i_gh);
921         return ret;
922 }
923 
924 /**
925  * gfs2_set_page_dirty - Page dirtying function
926  * @page: The page to dirty
927  *
928  * Returns: 1 if it dirtyed the page, or 0 otherwise
929  */
930  
931 static int gfs2_set_page_dirty(struct page *page)
932 {
933         SetPageChecked(page);
934         return __set_page_dirty_buffers(page);
935 }
936 
937 /**
938  * gfs2_bmap - Block map function
939  * @mapping: Address space info
940  * @lblock: The block to map
941  *
942  * Returns: The disk address for the block or 0 on hole or error
943  */
944 
945 static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
946 {
947         struct gfs2_inode *ip = GFS2_I(mapping->host);
948         struct gfs2_holder i_gh;
949         sector_t dblock = 0;
950         int error;
951 
952         error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
953         if (error)
954                 return 0;
955 
956         if (!gfs2_is_stuffed(ip))
957                 dblock = generic_block_bmap(mapping, lblock, gfs2_block_map);
958 
959         gfs2_glock_dq_uninit(&i_gh);
960 
961         return dblock;
962 }
963 
964 static void gfs2_discard(struct gfs2_sbd *sdp, struct buffer_head *bh)
965 {
966         struct gfs2_bufdata *bd;
967 
968         lock_buffer(bh);
969         gfs2_log_lock(sdp);
970         clear_buffer_dirty(bh);
971         bd = bh->b_private;
972         if (bd) {
973                 if (!list_empty(&bd->bd_list) && !buffer_pinned(bh))
974                         list_del_init(&bd->bd_list);
975                 else
976                         gfs2_remove_from_journal(bh, current->journal_info, 0);
977         }
978         bh->b_bdev = NULL;
979         clear_buffer_mapped(bh);
980         clear_buffer_req(bh);
981         clear_buffer_new(bh);
982         gfs2_log_unlock(sdp);
983         unlock_buffer(bh);
984 }
985 
986 static void gfs2_invalidatepage(struct page *page, unsigned int offset,
987                                 unsigned int length)
988 {
989         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
990         unsigned int stop = offset + length;
991         int partial_page = (offset || length < PAGE_CACHE_SIZE);
992         struct buffer_head *bh, *head;
993         unsigned long pos = 0;
994 
995         BUG_ON(!PageLocked(page));
996         if (!partial_page)
997                 ClearPageChecked(page);
998         if (!page_has_buffers(page))
999                 goto out;
1000 
1001         bh = head = page_buffers(page);
1002         do {
1003                 if (pos + bh->b_size > stop)
1004                         return;
1005 
1006                 if (offset <= pos)
1007                         gfs2_discard(sdp, bh);
1008                 pos += bh->b_size;
1009                 bh = bh->b_this_page;
1010         } while (bh != head);
1011 out:
1012         if (!partial_page)
1013                 try_to_release_page(page, 0);
1014 }
1015 
1016 /**
1017  * gfs2_ok_for_dio - check that dio is valid on this file
1018  * @ip: The inode
1019  * @offset: The offset at which we are reading or writing
1020  *
1021  * Returns: 0 (to ignore the i/o request and thus fall back to buffered i/o)
1022  *          1 (to accept the i/o request)
1023  */
1024 static int gfs2_ok_for_dio(struct gfs2_inode *ip, loff_t offset)
1025 {
1026         /*
1027          * Should we return an error here? I can't see that O_DIRECT for
1028          * a stuffed file makes any sense. For now we'll silently fall
1029          * back to buffered I/O
1030          */
1031         if (gfs2_is_stuffed(ip))
1032                 return 0;
1033 
1034         if (offset >= i_size_read(&ip->i_inode))
1035                 return 0;
1036         return 1;
1037 }
1038 
1039 
1040 
1041 static ssize_t gfs2_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
1042                               loff_t offset)
1043 {
1044         struct file *file = iocb->ki_filp;
1045         struct inode *inode = file->f_mapping->host;
1046         struct address_space *mapping = inode->i_mapping;
1047         struct gfs2_inode *ip = GFS2_I(inode);
1048         struct gfs2_holder gh;
1049         int rv;
1050 
1051         /*
1052          * Deferred lock, even if its a write, since we do no allocation
1053          * on this path. All we need change is atime, and this lock mode
1054          * ensures that other nodes have flushed their buffered read caches
1055          * (i.e. their page cache entries for this inode). We do not,
1056          * unfortunately have the option of only flushing a range like
1057          * the VFS does.
1058          */
1059         gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, 0, &gh);
1060         rv = gfs2_glock_nq(&gh);
1061         if (rv)
1062                 return rv;
1063         rv = gfs2_ok_for_dio(ip, offset);
1064         if (rv != 1)
1065                 goto out; /* dio not valid, fall back to buffered i/o */
1066 
1067         /*
1068          * Now since we are holding a deferred (CW) lock at this point, you
1069          * might be wondering why this is ever needed. There is a case however
1070          * where we've granted a deferred local lock against a cached exclusive
1071          * glock. That is ok provided all granted local locks are deferred, but
1072          * it also means that it is possible to encounter pages which are
1073          * cached and possibly also mapped. So here we check for that and sort
1074          * them out ahead of the dio. The glock state machine will take care of
1075          * everything else.
1076          *
1077          * If in fact the cached glock state (gl->gl_state) is deferred (CW) in
1078          * the first place, mapping->nr_pages will always be zero.
1079          */
1080         if (mapping->nrpages) {
1081                 loff_t lstart = offset & (PAGE_CACHE_SIZE - 1);
1082                 loff_t len = iov_iter_count(iter);
1083                 loff_t end = PAGE_ALIGN(offset + len) - 1;
1084 
1085                 rv = 0;
1086                 if (len == 0)
1087                         goto out;
1088                 if (test_and_clear_bit(GIF_SW_PAGED, &ip->i_flags))
1089                         unmap_shared_mapping_range(ip->i_inode.i_mapping, offset, len);
1090                 rv = filemap_write_and_wait_range(mapping, lstart, end);
1091                 if (rv)
1092                         goto out;
1093                 if (iov_iter_rw(iter) == WRITE)
1094                         truncate_inode_pages_range(mapping, lstart, end);
1095         }
1096 
1097         rv = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, iter,
1098                                   offset, gfs2_get_block_direct, NULL, NULL, 0);
1099 out:
1100         gfs2_glock_dq(&gh);
1101         gfs2_holder_uninit(&gh);
1102         return rv;
1103 }
1104 
1105 /**
1106  * gfs2_releasepage - free the metadata associated with a page
1107  * @page: the page that's being released
1108  * @gfp_mask: passed from Linux VFS, ignored by us
1109  *
1110  * Call try_to_free_buffers() if the buffers in this page can be
1111  * released.
1112  *
1113  * Returns: 0
1114  */
1115 
1116 int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
1117 {
1118         struct address_space *mapping = page->mapping;
1119         struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
1120         struct buffer_head *bh, *head;
1121         struct gfs2_bufdata *bd;
1122 
1123         if (!page_has_buffers(page))
1124                 return 0;
1125 
1126         gfs2_log_lock(sdp);
1127         spin_lock(&sdp->sd_ail_lock);
1128         head = bh = page_buffers(page);
1129         do {
1130                 if (atomic_read(&bh->b_count))
1131                         goto cannot_release;
1132                 bd = bh->b_private;
1133                 if (bd && bd->bd_tr)
1134                         goto cannot_release;
1135                 if (buffer_pinned(bh) || buffer_dirty(bh))
1136                         goto not_possible;
1137                 bh = bh->b_this_page;
1138         } while(bh != head);
1139         spin_unlock(&sdp->sd_ail_lock);
1140 
1141         head = bh = page_buffers(page);
1142         do {
1143                 bd = bh->b_private;
1144                 if (bd) {
1145                         gfs2_assert_warn(sdp, bd->bd_bh == bh);
1146                         if (!list_empty(&bd->bd_list))
1147                                 list_del_init(&bd->bd_list);
1148                         bd->bd_bh = NULL;
1149                         bh->b_private = NULL;
1150                         kmem_cache_free(gfs2_bufdata_cachep, bd);
1151                 }
1152 
1153                 bh = bh->b_this_page;
1154         } while (bh != head);
1155         gfs2_log_unlock(sdp);
1156 
1157         return try_to_free_buffers(page);
1158 
1159 not_possible: /* Should never happen */
1160         WARN_ON(buffer_dirty(bh));
1161         WARN_ON(buffer_pinned(bh));
1162 cannot_release:
1163         spin_unlock(&sdp->sd_ail_lock);
1164         gfs2_log_unlock(sdp);
1165         return 0;
1166 }
1167 
1168 static const struct address_space_operations gfs2_writeback_aops = {
1169         .writepage = gfs2_writepage,
1170         .writepages = gfs2_writepages,
1171         .readpage = gfs2_readpage,
1172         .readpages = gfs2_readpages,
1173         .write_begin = gfs2_write_begin,
1174         .write_end = gfs2_write_end,
1175         .bmap = gfs2_bmap,
1176         .invalidatepage = gfs2_invalidatepage,
1177         .releasepage = gfs2_releasepage,
1178         .direct_IO = gfs2_direct_IO,
1179         .migratepage = buffer_migrate_page,
1180         .is_partially_uptodate = block_is_partially_uptodate,
1181         .error_remove_page = generic_error_remove_page,
1182 };
1183 
1184 static const struct address_space_operations gfs2_ordered_aops = {
1185         .writepage = gfs2_writepage,
1186         .writepages = gfs2_writepages,
1187         .readpage = gfs2_readpage,
1188         .readpages = gfs2_readpages,
1189         .write_begin = gfs2_write_begin,
1190         .write_end = gfs2_write_end,
1191         .set_page_dirty = gfs2_set_page_dirty,
1192         .bmap = gfs2_bmap,
1193         .invalidatepage = gfs2_invalidatepage,
1194         .releasepage = gfs2_releasepage,
1195         .direct_IO = gfs2_direct_IO,
1196         .migratepage = buffer_migrate_page,
1197         .is_partially_uptodate = block_is_partially_uptodate,
1198         .error_remove_page = generic_error_remove_page,
1199 };
1200 
1201 static const struct address_space_operations gfs2_jdata_aops = {
1202         .writepage = gfs2_jdata_writepage,
1203         .writepages = gfs2_jdata_writepages,
1204         .readpage = gfs2_readpage,
1205         .readpages = gfs2_readpages,
1206         .write_begin = gfs2_write_begin,
1207         .write_end = gfs2_write_end,
1208         .set_page_dirty = gfs2_set_page_dirty,
1209         .bmap = gfs2_bmap,
1210         .invalidatepage = gfs2_invalidatepage,
1211         .releasepage = gfs2_releasepage,
1212         .is_partially_uptodate = block_is_partially_uptodate,
1213         .error_remove_page = generic_error_remove_page,
1214 };
1215 
1216 void gfs2_set_aops(struct inode *inode)
1217 {
1218         struct gfs2_inode *ip = GFS2_I(inode);
1219 
1220         if (gfs2_is_writeback(ip))
1221                 inode->i_mapping->a_ops = &gfs2_writeback_aops;
1222         else if (gfs2_is_ordered(ip))
1223                 inode->i_mapping->a_ops = &gfs2_ordered_aops;
1224         else if (gfs2_is_jdata(ip))
1225                 inode->i_mapping->a_ops = &gfs2_jdata_aops;
1226         else
1227                 BUG();
1228 }
1229 
1230 

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