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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 len)
 43 {
 44         struct buffer_head *head = page_buffers(page);
 45         unsigned int bsize = head->b_size;
 46         struct buffer_head *bh;
 47         unsigned int to = from + len;
 48         unsigned int start, end;
 49 
 50         for (bh = head, start = 0; bh != head || !start;
 51              bh = bh->b_this_page, start = end) {
 52                 end = start + bsize;
 53                 if (end <= from)
 54                         continue;
 55                 if (start >= to)
 56                         break;
 57                 set_buffer_uptodate(bh);
 58                 gfs2_trans_add_data(ip->i_gl, bh);
 59         }
 60 }
 61 
 62 /**
 63  * gfs2_get_block_noalloc - Fills in a buffer head with details about a block
 64  * @inode: The inode
 65  * @lblock: The block number to look up
 66  * @bh_result: The buffer head to return the result in
 67  * @create: Non-zero if we may add block to the file
 68  *
 69  * Returns: errno
 70  */
 71 
 72 static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock,
 73                                   struct buffer_head *bh_result, int create)
 74 {
 75         int error;
 76 
 77         error = gfs2_block_map(inode, lblock, bh_result, 0);
 78         if (error)
 79                 return error;
 80         if (!buffer_mapped(bh_result))
 81                 return -EIO;
 82         return 0;
 83 }
 84 
 85 static int gfs2_get_block_direct(struct inode *inode, sector_t lblock,
 86                                  struct buffer_head *bh_result, int create)
 87 {
 88         return gfs2_block_map(inode, lblock, bh_result, 0);
 89 }
 90 
 91 /**
 92  * gfs2_writepage_common - Common bits of writepage
 93  * @page: The page to be written
 94  * @wbc: The writeback control
 95  *
 96  * Returns: 1 if writepage is ok, otherwise an error code or zero if no error.
 97  */
 98 
 99 static int gfs2_writepage_common(struct page *page,
100                                  struct writeback_control *wbc)
101 {
102         struct inode *inode = page->mapping->host;
103         struct gfs2_inode *ip = GFS2_I(inode);
104         struct gfs2_sbd *sdp = GFS2_SB(inode);
105         loff_t i_size = i_size_read(inode);
106         pgoff_t end_index = i_size >> PAGE_SHIFT;
107         unsigned offset;
108 
109         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
110                 goto out;
111         if (current->journal_info)
112                 goto redirty;
113         /* Is the page fully outside i_size? (truncate in progress) */
114         offset = i_size & (PAGE_SIZE-1);
115         if (page->index > end_index || (page->index == end_index && !offset)) {
116                 page->mapping->a_ops->invalidatepage(page, 0, PAGE_SIZE);
117                 goto out;
118         }
119         return 1;
120 redirty:
121         redirty_page_for_writepage(wbc, page);
122 out:
123         unlock_page(page);
124         return 0;
125 }
126 
127 /**
128  * gfs2_writepage - Write page for writeback mappings
129  * @page: The page
130  * @wbc: The writeback control
131  *
132  */
133 
134 static int gfs2_writepage(struct page *page, struct writeback_control *wbc)
135 {
136         int ret;
137 
138         ret = gfs2_writepage_common(page, wbc);
139         if (ret <= 0)
140                 return ret;
141 
142         return nobh_writepage(page, gfs2_get_block_noalloc, wbc);
143 }
144 
145 /* This is the same as calling block_write_full_page, but it also
146  * writes pages outside of i_size
147  */
148 static int gfs2_write_full_page(struct page *page, get_block_t *get_block,
149                                 struct writeback_control *wbc)
150 {
151         struct inode * const inode = page->mapping->host;
152         loff_t i_size = i_size_read(inode);
153         const pgoff_t end_index = i_size >> PAGE_SHIFT;
154         unsigned offset;
155 
156         /*
157          * The page straddles i_size.  It must be zeroed out on each and every
158          * writepage invocation because it may be mmapped.  "A file is mapped
159          * in multiples of the page size.  For a file that is not a multiple of
160          * the  page size, the remaining memory is zeroed when mapped, and
161          * writes to that region are not written out to the file."
162          */
163         offset = i_size & (PAGE_SIZE-1);
164         if (page->index == end_index && offset)
165                 zero_user_segment(page, offset, PAGE_SIZE);
166 
167         return __block_write_full_page(inode, page, get_block, wbc,
168                                        end_buffer_async_write);
169 }
170 
171 /**
172  * __gfs2_jdata_writepage - The core of jdata writepage
173  * @page: The page to write
174  * @wbc: The writeback control
175  *
176  * This is shared between writepage and writepages and implements the
177  * core of the writepage operation. If a transaction is required then
178  * PageChecked will have been set and the transaction will have
179  * already been started before this is called.
180  */
181 
182 static int __gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
183 {
184         struct inode *inode = page->mapping->host;
185         struct gfs2_inode *ip = GFS2_I(inode);
186         struct gfs2_sbd *sdp = GFS2_SB(inode);
187 
188         if (PageChecked(page)) {
189                 ClearPageChecked(page);
190                 if (!page_has_buffers(page)) {
191                         create_empty_buffers(page, inode->i_sb->s_blocksize,
192                                              BIT(BH_Dirty)|BIT(BH_Uptodate));
193                 }
194                 gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize);
195         }
196         return gfs2_write_full_page(page, gfs2_get_block_noalloc, wbc);
197 }
198 
199 /**
200  * gfs2_jdata_writepage - Write complete page
201  * @page: Page to write
202  * @wbc: The writeback control
203  *
204  * Returns: errno
205  *
206  */
207 
208 static int gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
209 {
210         struct inode *inode = page->mapping->host;
211         struct gfs2_inode *ip = GFS2_I(inode);
212         struct gfs2_sbd *sdp = GFS2_SB(inode);
213         int ret;
214 
215         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
216                 goto out;
217         if (PageChecked(page) || current->journal_info)
218                 goto out_ignore;
219         ret = __gfs2_jdata_writepage(page, wbc);
220         return ret;
221 
222 out_ignore:
223         redirty_page_for_writepage(wbc, page);
224 out:
225         unlock_page(page);
226         return 0;
227 }
228 
229 /**
230  * gfs2_writepages - Write a bunch of dirty pages back to disk
231  * @mapping: The mapping to write
232  * @wbc: Write-back control
233  *
234  * Used for both ordered and writeback modes.
235  */
236 static int gfs2_writepages(struct address_space *mapping,
237                            struct writeback_control *wbc)
238 {
239         struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
240         int ret = mpage_writepages(mapping, wbc, gfs2_get_block_noalloc);
241 
242         /*
243          * Even if we didn't write any pages here, we might still be holding
244          * dirty pages in the ail. We forcibly flush the ail because we don't
245          * want balance_dirty_pages() to loop indefinitely trying to write out
246          * pages held in the ail that it can't find.
247          */
248         if (ret == 0)
249                 set_bit(SDF_FORCE_AIL_FLUSH, &sdp->sd_flags);
250 
251         return ret;
252 }
253 
254 /**
255  * gfs2_write_jdata_pagevec - Write back a pagevec's worth of pages
256  * @mapping: The mapping
257  * @wbc: The writeback control
258  * @pvec: The vector of pages
259  * @nr_pages: The number of pages to write
260  * @done_index: Page index
261  *
262  * Returns: non-zero if loop should terminate, zero otherwise
263  */
264 
265 static int gfs2_write_jdata_pagevec(struct address_space *mapping,
266                                     struct writeback_control *wbc,
267                                     struct pagevec *pvec,
268                                     int nr_pages,
269                                     pgoff_t *done_index)
270 {
271         struct inode *inode = mapping->host;
272         struct gfs2_sbd *sdp = GFS2_SB(inode);
273         unsigned nrblocks = nr_pages * (PAGE_SIZE/inode->i_sb->s_blocksize);
274         int i;
275         int ret;
276 
277         ret = gfs2_trans_begin(sdp, nrblocks, nrblocks);
278         if (ret < 0)
279                 return ret;
280 
281         for(i = 0; i < nr_pages; i++) {
282                 struct page *page = pvec->pages[i];
283 
284                 *done_index = page->index;
285 
286                 lock_page(page);
287 
288                 if (unlikely(page->mapping != mapping)) {
289 continue_unlock:
290                         unlock_page(page);
291                         continue;
292                 }
293 
294                 if (!PageDirty(page)) {
295                         /* someone wrote it for us */
296                         goto continue_unlock;
297                 }
298 
299                 if (PageWriteback(page)) {
300                         if (wbc->sync_mode != WB_SYNC_NONE)
301                                 wait_on_page_writeback(page);
302                         else
303                                 goto continue_unlock;
304                 }
305 
306                 BUG_ON(PageWriteback(page));
307                 if (!clear_page_dirty_for_io(page))
308                         goto continue_unlock;
309 
310                 trace_wbc_writepage(wbc, inode_to_bdi(inode));
311 
312                 ret = __gfs2_jdata_writepage(page, wbc);
313                 if (unlikely(ret)) {
314                         if (ret == AOP_WRITEPAGE_ACTIVATE) {
315                                 unlock_page(page);
316                                 ret = 0;
317                         } else {
318 
319                                 /*
320                                  * done_index is set past this page,
321                                  * so media errors will not choke
322                                  * background writeout for the entire
323                                  * file. This has consequences for
324                                  * range_cyclic semantics (ie. it may
325                                  * not be suitable for data integrity
326                                  * writeout).
327                                  */
328                                 *done_index = page->index + 1;
329                                 ret = 1;
330                                 break;
331                         }
332                 }
333 
334                 /*
335                  * We stop writing back only if we are not doing
336                  * integrity sync. In case of integrity sync we have to
337                  * keep going until we have written all the pages
338                  * we tagged for writeback prior to entering this loop.
339                  */
340                 if (--wbc->nr_to_write <= 0 && wbc->sync_mode == WB_SYNC_NONE) {
341                         ret = 1;
342                         break;
343                 }
344 
345         }
346         gfs2_trans_end(sdp);
347         return ret;
348 }
349 
350 /**
351  * gfs2_write_cache_jdata - Like write_cache_pages but different
352  * @mapping: The mapping to write
353  * @wbc: The writeback control
354  *
355  * The reason that we use our own function here is that we need to
356  * start transactions before we grab page locks. This allows us
357  * to get the ordering right.
358  */
359 
360 static int gfs2_write_cache_jdata(struct address_space *mapping,
361                                   struct writeback_control *wbc)
362 {
363         int ret = 0;
364         int done = 0;
365         struct pagevec pvec;
366         int nr_pages;
367         pgoff_t uninitialized_var(writeback_index);
368         pgoff_t index;
369         pgoff_t end;
370         pgoff_t done_index;
371         int cycled;
372         int range_whole = 0;
373         int tag;
374 
375         pagevec_init(&pvec);
376         if (wbc->range_cyclic) {
377                 writeback_index = mapping->writeback_index; /* prev offset */
378                 index = writeback_index;
379                 if (index == 0)
380                         cycled = 1;
381                 else
382                         cycled = 0;
383                 end = -1;
384         } else {
385                 index = wbc->range_start >> PAGE_SHIFT;
386                 end = wbc->range_end >> PAGE_SHIFT;
387                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
388                         range_whole = 1;
389                 cycled = 1; /* ignore range_cyclic tests */
390         }
391         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
392                 tag = PAGECACHE_TAG_TOWRITE;
393         else
394                 tag = PAGECACHE_TAG_DIRTY;
395 
396 retry:
397         if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
398                 tag_pages_for_writeback(mapping, index, end);
399         done_index = index;
400         while (!done && (index <= end)) {
401                 nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index, end,
402                                 tag);
403                 if (nr_pages == 0)
404                         break;
405 
406                 ret = gfs2_write_jdata_pagevec(mapping, wbc, &pvec, nr_pages, &done_index);
407                 if (ret)
408                         done = 1;
409                 if (ret > 0)
410                         ret = 0;
411                 pagevec_release(&pvec);
412                 cond_resched();
413         }
414 
415         if (!cycled && !done) {
416                 /*
417                  * range_cyclic:
418                  * We hit the last page and there is more work to be done: wrap
419                  * back to the start of the file
420                  */
421                 cycled = 1;
422                 index = 0;
423                 end = writeback_index - 1;
424                 goto retry;
425         }
426 
427         if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
428                 mapping->writeback_index = done_index;
429 
430         return ret;
431 }
432 
433 
434 /**
435  * gfs2_jdata_writepages - Write a bunch of dirty pages back to disk
436  * @mapping: The mapping to write
437  * @wbc: The writeback control
438  * 
439  */
440 
441 static int gfs2_jdata_writepages(struct address_space *mapping,
442                                  struct writeback_control *wbc)
443 {
444         struct gfs2_inode *ip = GFS2_I(mapping->host);
445         struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
446         int ret;
447 
448         ret = gfs2_write_cache_jdata(mapping, wbc);
449         if (ret == 0 && wbc->sync_mode == WB_SYNC_ALL) {
450                 gfs2_log_flush(sdp, ip->i_gl, GFS2_LOG_HEAD_FLUSH_NORMAL |
451                                GFS2_LFC_JDATA_WPAGES);
452                 ret = gfs2_write_cache_jdata(mapping, wbc);
453         }
454         return ret;
455 }
456 
457 /**
458  * stuffed_readpage - Fill in a Linux page with stuffed file data
459  * @ip: the inode
460  * @page: the page
461  *
462  * Returns: errno
463  */
464 
465 static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
466 {
467         struct buffer_head *dibh;
468         u64 dsize = i_size_read(&ip->i_inode);
469         void *kaddr;
470         int error;
471 
472         /*
473          * Due to the order of unstuffing files and ->fault(), we can be
474          * asked for a zero page in the case of a stuffed file being extended,
475          * so we need to supply one here. It doesn't happen often.
476          */
477         if (unlikely(page->index)) {
478                 zero_user(page, 0, PAGE_SIZE);
479                 SetPageUptodate(page);
480                 return 0;
481         }
482 
483         error = gfs2_meta_inode_buffer(ip, &dibh);
484         if (error)
485                 return error;
486 
487         kaddr = kmap_atomic(page);
488         if (dsize > gfs2_max_stuffed_size(ip))
489                 dsize = gfs2_max_stuffed_size(ip);
490         memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize);
491         memset(kaddr + dsize, 0, PAGE_SIZE - dsize);
492         kunmap_atomic(kaddr);
493         flush_dcache_page(page);
494         brelse(dibh);
495         SetPageUptodate(page);
496 
497         return 0;
498 }
499 
500 
501 /**
502  * __gfs2_readpage - readpage
503  * @file: The file to read a page for
504  * @page: The page to read
505  *
506  * This is the core of gfs2's readpage. It's used by the internal file
507  * reading code as in that case we already hold the glock. Also it's
508  * called by gfs2_readpage() once the required lock has been granted.
509  */
510 
511 static int __gfs2_readpage(void *file, struct page *page)
512 {
513         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
514         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
515         int error;
516 
517         if (gfs2_is_stuffed(ip)) {
518                 error = stuffed_readpage(ip, page);
519                 unlock_page(page);
520         } else {
521                 error = mpage_readpage(page, gfs2_block_map);
522         }
523 
524         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
525                 return -EIO;
526 
527         return error;
528 }
529 
530 /**
531  * gfs2_readpage - read a page of a file
532  * @file: The file to read
533  * @page: The page of the file
534  *
535  * This deals with the locking required. We have to unlock and
536  * relock the page in order to get the locking in the right
537  * order.
538  */
539 
540 static int gfs2_readpage(struct file *file, struct page *page)
541 {
542         struct address_space *mapping = page->mapping;
543         struct gfs2_inode *ip = GFS2_I(mapping->host);
544         struct gfs2_holder gh;
545         int error;
546 
547         unlock_page(page);
548         gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
549         error = gfs2_glock_nq(&gh);
550         if (unlikely(error))
551                 goto out;
552         error = AOP_TRUNCATED_PAGE;
553         lock_page(page);
554         if (page->mapping == mapping && !PageUptodate(page))
555                 error = __gfs2_readpage(file, page);
556         else
557                 unlock_page(page);
558         gfs2_glock_dq(&gh);
559 out:
560         gfs2_holder_uninit(&gh);
561         if (error && error != AOP_TRUNCATED_PAGE)
562                 lock_page(page);
563         return error;
564 }
565 
566 /**
567  * gfs2_internal_read - read an internal file
568  * @ip: The gfs2 inode
569  * @buf: The buffer to fill
570  * @pos: The file position
571  * @size: The amount to read
572  *
573  */
574 
575 int gfs2_internal_read(struct gfs2_inode *ip, char *buf, loff_t *pos,
576                        unsigned size)
577 {
578         struct address_space *mapping = ip->i_inode.i_mapping;
579         unsigned long index = *pos / PAGE_SIZE;
580         unsigned offset = *pos & (PAGE_SIZE - 1);
581         unsigned copied = 0;
582         unsigned amt;
583         struct page *page;
584         void *p;
585 
586         do {
587                 amt = size - copied;
588                 if (offset + size > PAGE_SIZE)
589                         amt = PAGE_SIZE - offset;
590                 page = read_cache_page(mapping, index, __gfs2_readpage, NULL);
591                 if (IS_ERR(page))
592                         return PTR_ERR(page);
593                 p = kmap_atomic(page);
594                 memcpy(buf + copied, p + offset, amt);
595                 kunmap_atomic(p);
596                 put_page(page);
597                 copied += amt;
598                 index++;
599                 offset = 0;
600         } while(copied < size);
601         (*pos) += size;
602         return size;
603 }
604 
605 /**
606  * gfs2_readpages - Read a bunch of pages at once
607  * @file: The file to read from
608  * @mapping: Address space info
609  * @pages: List of pages to read
610  * @nr_pages: Number of pages to read
611  *
612  * Some notes:
613  * 1. This is only for readahead, so we can simply ignore any things
614  *    which are slightly inconvenient (such as locking conflicts between
615  *    the page lock and the glock) and return having done no I/O. Its
616  *    obviously not something we'd want to do on too regular a basis.
617  *    Any I/O we ignore at this time will be done via readpage later.
618  * 2. We don't handle stuffed files here we let readpage do the honours.
619  * 3. mpage_readpages() does most of the heavy lifting in the common case.
620  * 4. gfs2_block_map() is relied upon to set BH_Boundary in the right places.
621  */
622 
623 static int gfs2_readpages(struct file *file, struct address_space *mapping,
624                           struct list_head *pages, unsigned nr_pages)
625 {
626         struct inode *inode = mapping->host;
627         struct gfs2_inode *ip = GFS2_I(inode);
628         struct gfs2_sbd *sdp = GFS2_SB(inode);
629         struct gfs2_holder gh;
630         int ret;
631 
632         gfs2_holder_init(ip->i_gl, LM_ST_SHARED, 0, &gh);
633         ret = gfs2_glock_nq(&gh);
634         if (unlikely(ret))
635                 goto out_uninit;
636         if (!gfs2_is_stuffed(ip))
637                 ret = mpage_readpages(mapping, pages, nr_pages, gfs2_block_map);
638         gfs2_glock_dq(&gh);
639 out_uninit:
640         gfs2_holder_uninit(&gh);
641         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
642                 ret = -EIO;
643         return ret;
644 }
645 
646 /**
647  * gfs2_write_begin - Begin to write to a file
648  * @file: The file to write to
649  * @mapping: The mapping in which to write
650  * @pos: The file offset at which to start writing
651  * @len: Length of the write
652  * @flags: Various flags
653  * @pagep: Pointer to return the page
654  * @fsdata: Pointer to return fs data (unused by GFS2)
655  *
656  * Returns: errno
657  */
658 
659 static int gfs2_write_begin(struct file *file, struct address_space *mapping,
660                             loff_t pos, unsigned len, unsigned flags,
661                             struct page **pagep, void **fsdata)
662 {
663         struct gfs2_inode *ip = GFS2_I(mapping->host);
664         struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
665         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
666         unsigned int data_blocks = 0, ind_blocks = 0, rblocks;
667         unsigned requested = 0;
668         int alloc_required;
669         int error = 0;
670         pgoff_t index = pos >> PAGE_SHIFT;
671         unsigned from = pos & (PAGE_SIZE - 1);
672         struct page *page;
673 
674         gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &ip->i_gh);
675         error = gfs2_glock_nq(&ip->i_gh);
676         if (unlikely(error))
677                 goto out_uninit;
678         if (&ip->i_inode == sdp->sd_rindex) {
679                 error = gfs2_glock_nq_init(m_ip->i_gl, LM_ST_EXCLUSIVE,
680                                            GL_NOCACHE, &m_ip->i_gh);
681                 if (unlikely(error)) {
682                         gfs2_glock_dq(&ip->i_gh);
683                         goto out_uninit;
684                 }
685         }
686 
687         alloc_required = gfs2_write_alloc_required(ip, pos, len);
688 
689         if (alloc_required || gfs2_is_jdata(ip))
690                 gfs2_write_calc_reserv(ip, len, &data_blocks, &ind_blocks);
691 
692         if (alloc_required) {
693                 struct gfs2_alloc_parms ap = { .aflags = 0, };
694                 requested = data_blocks + ind_blocks;
695                 ap.target = requested;
696                 error = gfs2_quota_lock_check(ip, &ap);
697                 if (error)
698                         goto out_unlock;
699 
700                 error = gfs2_inplace_reserve(ip, &ap);
701                 if (error)
702                         goto out_qunlock;
703         }
704 
705         rblocks = RES_DINODE + ind_blocks;
706         if (gfs2_is_jdata(ip))
707                 rblocks += data_blocks ? data_blocks : 1;
708         if (ind_blocks || data_blocks)
709                 rblocks += RES_STATFS + RES_QUOTA;
710         if (&ip->i_inode == sdp->sd_rindex)
711                 rblocks += 2 * RES_STATFS;
712         if (alloc_required)
713                 rblocks += gfs2_rg_blocks(ip, requested);
714 
715         error = gfs2_trans_begin(sdp, rblocks,
716                                  PAGE_SIZE/sdp->sd_sb.sb_bsize);
717         if (error)
718                 goto out_trans_fail;
719 
720         error = -ENOMEM;
721         flags |= AOP_FLAG_NOFS;
722         page = grab_cache_page_write_begin(mapping, index, flags);
723         *pagep = page;
724         if (unlikely(!page))
725                 goto out_endtrans;
726 
727         if (gfs2_is_stuffed(ip)) {
728                 error = 0;
729                 if (pos + len > gfs2_max_stuffed_size(ip)) {
730                         error = gfs2_unstuff_dinode(ip, page);
731                         if (error == 0)
732                                 goto prepare_write;
733                 } else if (!PageUptodate(page)) {
734                         error = stuffed_readpage(ip, page);
735                 }
736                 goto out;
737         }
738 
739 prepare_write:
740         error = __block_write_begin(page, from, len, gfs2_block_map);
741 out:
742         if (error == 0)
743                 return 0;
744 
745         unlock_page(page);
746         put_page(page);
747 
748         gfs2_trans_end(sdp);
749         if (alloc_required) {
750                 gfs2_inplace_release(ip);
751                 if (pos + len > ip->i_inode.i_size)
752                         gfs2_trim_blocks(&ip->i_inode);
753         }
754         goto out_qunlock;
755 
756 out_endtrans:
757         gfs2_trans_end(sdp);
758 out_trans_fail:
759         if (alloc_required)
760                 gfs2_inplace_release(ip);
761 out_qunlock:
762         if (alloc_required)
763                 gfs2_quota_unlock(ip);
764 out_unlock:
765         if (&ip->i_inode == sdp->sd_rindex) {
766                 gfs2_glock_dq(&m_ip->i_gh);
767                 gfs2_holder_uninit(&m_ip->i_gh);
768         }
769         gfs2_glock_dq(&ip->i_gh);
770 out_uninit:
771         gfs2_holder_uninit(&ip->i_gh);
772         return error;
773 }
774 
775 /**
776  * adjust_fs_space - Adjusts the free space available due to gfs2_grow
777  * @inode: the rindex inode
778  */
779 static void adjust_fs_space(struct inode *inode)
780 {
781         struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
782         struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
783         struct gfs2_inode *l_ip = GFS2_I(sdp->sd_sc_inode);
784         struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
785         struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
786         struct buffer_head *m_bh, *l_bh;
787         u64 fs_total, new_free;
788 
789         /* Total up the file system space, according to the latest rindex. */
790         fs_total = gfs2_ri_total(sdp);
791         if (gfs2_meta_inode_buffer(m_ip, &m_bh) != 0)
792                 return;
793 
794         spin_lock(&sdp->sd_statfs_spin);
795         gfs2_statfs_change_in(m_sc, m_bh->b_data +
796                               sizeof(struct gfs2_dinode));
797         if (fs_total > (m_sc->sc_total + l_sc->sc_total))
798                 new_free = fs_total - (m_sc->sc_total + l_sc->sc_total);
799         else
800                 new_free = 0;
801         spin_unlock(&sdp->sd_statfs_spin);
802         fs_warn(sdp, "File system extended by %llu blocks.\n",
803                 (unsigned long long)new_free);
804         gfs2_statfs_change(sdp, new_free, new_free, 0);
805 
806         if (gfs2_meta_inode_buffer(l_ip, &l_bh) != 0)
807                 goto out;
808         update_statfs(sdp, m_bh, l_bh);
809         brelse(l_bh);
810 out:
811         brelse(m_bh);
812 }
813 
814 /**
815  * gfs2_stuffed_write_end - Write end for stuffed files
816  * @inode: The inode
817  * @dibh: The buffer_head containing the on-disk inode
818  * @pos: The file position
819  * @copied: How much was actually copied by the VFS
820  * @page: The page
821  *
822  * This copies the data from the page into the inode block after
823  * the inode data structure itself.
824  *
825  * Returns: errno
826  */
827 static int gfs2_stuffed_write_end(struct inode *inode, struct buffer_head *dibh,
828                                   loff_t pos, unsigned copied,
829                                   struct page *page)
830 {
831         struct gfs2_inode *ip = GFS2_I(inode);
832         u64 to = pos + copied;
833         void *kaddr;
834         unsigned char *buf = dibh->b_data + sizeof(struct gfs2_dinode);
835 
836         BUG_ON(pos + copied > gfs2_max_stuffed_size(ip));
837 
838         kaddr = kmap_atomic(page);
839         memcpy(buf + pos, kaddr + pos, copied);
840         flush_dcache_page(page);
841         kunmap_atomic(kaddr);
842 
843         WARN_ON(!PageUptodate(page));
844         unlock_page(page);
845         put_page(page);
846 
847         if (copied) {
848                 if (inode->i_size < to)
849                         i_size_write(inode, to);
850                 mark_inode_dirty(inode);
851         }
852         return copied;
853 }
854 
855 /**
856  * gfs2_write_end
857  * @file: The file to write to
858  * @mapping: The address space to write to
859  * @pos: The file position
860  * @len: The length of the data
861  * @copied: How much was actually copied by the VFS
862  * @page: The page that has been written
863  * @fsdata: The fsdata (unused in GFS2)
864  *
865  * The main write_end function for GFS2. We just put our locking around the VFS
866  * 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         int ret;
881         struct gfs2_trans *tr = current->journal_info;
882         BUG_ON(!tr);
883 
884         BUG_ON(gfs2_glock_is_locked_by_me(ip->i_gl) == NULL);
885 
886         ret = gfs2_meta_inode_buffer(ip, &dibh);
887         if (unlikely(ret))
888                 goto out;
889 
890         if (gfs2_is_stuffed(ip)) {
891                 ret = gfs2_stuffed_write_end(inode, dibh, pos, copied, page);
892                 page = NULL;
893                 goto out2;
894         }
895 
896         if (gfs2_is_jdata(ip))
897                 gfs2_page_add_databufs(ip, page, pos & ~PAGE_MASK, len);
898         else
899                 gfs2_ordered_add_inode(ip);
900 
901         ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
902         page = NULL;
903         if (tr->tr_num_buf_new)
904                 __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
905         else
906                 gfs2_trans_add_meta(ip->i_gl, dibh);
907 
908 out2:
909         if (inode == sdp->sd_rindex) {
910                 adjust_fs_space(inode);
911                 sdp->sd_rindex_uptodate = 0;
912         }
913 
914         brelse(dibh);
915 out:
916         if (page) {
917                 unlock_page(page);
918                 put_page(page);
919         }
920         gfs2_trans_end(sdp);
921         gfs2_inplace_release(ip);
922         if (ip->i_qadata && ip->i_qadata->qa_qd_num)
923                 gfs2_quota_unlock(ip);
924         if (inode == sdp->sd_rindex) {
925                 gfs2_glock_dq(&m_ip->i_gh);
926                 gfs2_holder_uninit(&m_ip->i_gh);
927         }
928         gfs2_glock_dq(&ip->i_gh);
929         gfs2_holder_uninit(&ip->i_gh);
930         return ret;
931 }
932 
933 /**
934  * jdata_set_page_dirty - Page dirtying function
935  * @page: The page to dirty
936  *
937  * Returns: 1 if it dirtyed the page, or 0 otherwise
938  */
939  
940 static int jdata_set_page_dirty(struct page *page)
941 {
942         SetPageChecked(page);
943         return __set_page_dirty_buffers(page);
944 }
945 
946 /**
947  * gfs2_bmap - Block map function
948  * @mapping: Address space info
949  * @lblock: The block to map
950  *
951  * Returns: The disk address for the block or 0 on hole or error
952  */
953 
954 static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
955 {
956         struct gfs2_inode *ip = GFS2_I(mapping->host);
957         struct gfs2_holder i_gh;
958         sector_t dblock = 0;
959         int error;
960 
961         error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
962         if (error)
963                 return 0;
964 
965         if (!gfs2_is_stuffed(ip))
966                 dblock = generic_block_bmap(mapping, lblock, gfs2_block_map);
967 
968         gfs2_glock_dq_uninit(&i_gh);
969 
970         return dblock;
971 }
972 
973 static void gfs2_discard(struct gfs2_sbd *sdp, struct buffer_head *bh)
974 {
975         struct gfs2_bufdata *bd;
976 
977         lock_buffer(bh);
978         gfs2_log_lock(sdp);
979         clear_buffer_dirty(bh);
980         bd = bh->b_private;
981         if (bd) {
982                 if (!list_empty(&bd->bd_list) && !buffer_pinned(bh))
983                         list_del_init(&bd->bd_list);
984                 else
985                         gfs2_remove_from_journal(bh, REMOVE_JDATA);
986         }
987         bh->b_bdev = NULL;
988         clear_buffer_mapped(bh);
989         clear_buffer_req(bh);
990         clear_buffer_new(bh);
991         gfs2_log_unlock(sdp);
992         unlock_buffer(bh);
993 }
994 
995 static void gfs2_invalidatepage(struct page *page, unsigned int offset,
996                                 unsigned int length)
997 {
998         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
999         unsigned int stop = offset + length;
1000         int partial_page = (offset || length < PAGE_SIZE);
1001         struct buffer_head *bh, *head;
1002         unsigned long pos = 0;
1003 
1004         BUG_ON(!PageLocked(page));
1005         if (!partial_page)
1006                 ClearPageChecked(page);
1007         if (!page_has_buffers(page))
1008                 goto out;
1009 
1010         bh = head = page_buffers(page);
1011         do {
1012                 if (pos + bh->b_size > stop)
1013                         return;
1014 
1015                 if (offset <= pos)
1016                         gfs2_discard(sdp, bh);
1017                 pos += bh->b_size;
1018                 bh = bh->b_this_page;
1019         } while (bh != head);
1020 out:
1021         if (!partial_page)
1022                 try_to_release_page(page, 0);
1023 }
1024 
1025 /**
1026  * gfs2_ok_for_dio - check that dio is valid on this file
1027  * @ip: The inode
1028  * @offset: The offset at which we are reading or writing
1029  *
1030  * Returns: 0 (to ignore the i/o request and thus fall back to buffered i/o)
1031  *          1 (to accept the i/o request)
1032  */
1033 static int gfs2_ok_for_dio(struct gfs2_inode *ip, loff_t offset)
1034 {
1035         /*
1036          * Should we return an error here? I can't see that O_DIRECT for
1037          * a stuffed file makes any sense. For now we'll silently fall
1038          * back to buffered I/O
1039          */
1040         if (gfs2_is_stuffed(ip))
1041                 return 0;
1042 
1043         if (offset >= i_size_read(&ip->i_inode))
1044                 return 0;
1045         return 1;
1046 }
1047 
1048 
1049 
1050 static ssize_t gfs2_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
1051 {
1052         struct file *file = iocb->ki_filp;
1053         struct inode *inode = file->f_mapping->host;
1054         struct address_space *mapping = inode->i_mapping;
1055         struct gfs2_inode *ip = GFS2_I(inode);
1056         loff_t offset = iocb->ki_pos;
1057         struct gfs2_holder gh;
1058         int rv;
1059 
1060         /*
1061          * Deferred lock, even if its a write, since we do no allocation
1062          * on this path. All we need change is atime, and this lock mode
1063          * ensures that other nodes have flushed their buffered read caches
1064          * (i.e. their page cache entries for this inode). We do not,
1065          * unfortunately have the option of only flushing a range like
1066          * the VFS does.
1067          */
1068         gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, 0, &gh);
1069         rv = gfs2_glock_nq(&gh);
1070         if (rv)
1071                 goto out_uninit;
1072         rv = gfs2_ok_for_dio(ip, offset);
1073         if (rv != 1)
1074                 goto out; /* dio not valid, fall back to buffered i/o */
1075 
1076         /*
1077          * Now since we are holding a deferred (CW) lock at this point, you
1078          * might be wondering why this is ever needed. There is a case however
1079          * where we've granted a deferred local lock against a cached exclusive
1080          * glock. That is ok provided all granted local locks are deferred, but
1081          * it also means that it is possible to encounter pages which are
1082          * cached and possibly also mapped. So here we check for that and sort
1083          * them out ahead of the dio. The glock state machine will take care of
1084          * everything else.
1085          *
1086          * If in fact the cached glock state (gl->gl_state) is deferred (CW) in
1087          * the first place, mapping->nr_pages will always be zero.
1088          */
1089         if (mapping->nrpages) {
1090                 loff_t lstart = offset & ~(PAGE_SIZE - 1);
1091                 loff_t len = iov_iter_count(iter);
1092                 loff_t end = PAGE_ALIGN(offset + len) - 1;
1093 
1094                 rv = 0;
1095                 if (len == 0)
1096                         goto out;
1097                 if (test_and_clear_bit(GIF_SW_PAGED, &ip->i_flags))
1098                         unmap_shared_mapping_range(ip->i_inode.i_mapping, offset, len);
1099                 rv = filemap_write_and_wait_range(mapping, lstart, end);
1100                 if (rv)
1101                         goto out;
1102                 if (iov_iter_rw(iter) == WRITE)
1103                         truncate_inode_pages_range(mapping, lstart, end);
1104         }
1105 
1106         rv = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, iter,
1107                                   gfs2_get_block_direct, NULL, NULL, 0);
1108 out:
1109         gfs2_glock_dq(&gh);
1110 out_uninit:
1111         gfs2_holder_uninit(&gh);
1112         return rv;
1113 }
1114 
1115 /**
1116  * gfs2_releasepage - free the metadata associated with a page
1117  * @page: the page that's being released
1118  * @gfp_mask: passed from Linux VFS, ignored by us
1119  *
1120  * Call try_to_free_buffers() if the buffers in this page can be
1121  * released.
1122  *
1123  * Returns: 0
1124  */
1125 
1126 int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
1127 {
1128         struct address_space *mapping = page->mapping;
1129         struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
1130         struct buffer_head *bh, *head;
1131         struct gfs2_bufdata *bd;
1132 
1133         if (!page_has_buffers(page))
1134                 return 0;
1135 
1136         /*
1137          * From xfs_vm_releasepage: mm accommodates an old ext3 case where
1138          * clean pages might not have had the dirty bit cleared.  Thus, it can
1139          * send actual dirty pages to ->releasepage() via shrink_active_list().
1140          *
1141          * As a workaround, we skip pages that contain dirty buffers below.
1142          * Once ->releasepage isn't called on dirty pages anymore, we can warn
1143          * on dirty buffers like we used to here again.
1144          */
1145 
1146         gfs2_log_lock(sdp);
1147         spin_lock(&sdp->sd_ail_lock);
1148         head = bh = page_buffers(page);
1149         do {
1150                 if (atomic_read(&bh->b_count))
1151                         goto cannot_release;
1152                 bd = bh->b_private;
1153                 if (bd && bd->bd_tr)
1154                         goto cannot_release;
1155                 if (buffer_dirty(bh) || WARN_ON(buffer_pinned(bh)))
1156                         goto cannot_release;
1157                 bh = bh->b_this_page;
1158         } while(bh != head);
1159         spin_unlock(&sdp->sd_ail_lock);
1160 
1161         head = bh = page_buffers(page);
1162         do {
1163                 bd = bh->b_private;
1164                 if (bd) {
1165                         gfs2_assert_warn(sdp, bd->bd_bh == bh);
1166                         if (!list_empty(&bd->bd_list))
1167                                 list_del_init(&bd->bd_list);
1168                         bd->bd_bh = NULL;
1169                         bh->b_private = NULL;
1170                         kmem_cache_free(gfs2_bufdata_cachep, bd);
1171                 }
1172 
1173                 bh = bh->b_this_page;
1174         } while (bh != head);
1175         gfs2_log_unlock(sdp);
1176 
1177         return try_to_free_buffers(page);
1178 
1179 cannot_release:
1180         spin_unlock(&sdp->sd_ail_lock);
1181         gfs2_log_unlock(sdp);
1182         return 0;
1183 }
1184 
1185 static const struct address_space_operations gfs2_writeback_aops = {
1186         .writepage = gfs2_writepage,
1187         .writepages = gfs2_writepages,
1188         .readpage = gfs2_readpage,
1189         .readpages = gfs2_readpages,
1190         .write_begin = gfs2_write_begin,
1191         .write_end = gfs2_write_end,
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_ordered_aops = {
1202         .writepage = gfs2_writepage,
1203         .writepages = gfs2_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 = __set_page_dirty_buffers,
1209         .bmap = gfs2_bmap,
1210         .invalidatepage = gfs2_invalidatepage,
1211         .releasepage = gfs2_releasepage,
1212         .direct_IO = gfs2_direct_IO,
1213         .migratepage = buffer_migrate_page,
1214         .is_partially_uptodate = block_is_partially_uptodate,
1215         .error_remove_page = generic_error_remove_page,
1216 };
1217 
1218 static const struct address_space_operations gfs2_jdata_aops = {
1219         .writepage = gfs2_jdata_writepage,
1220         .writepages = gfs2_jdata_writepages,
1221         .readpage = gfs2_readpage,
1222         .readpages = gfs2_readpages,
1223         .write_begin = gfs2_write_begin,
1224         .write_end = gfs2_write_end,
1225         .set_page_dirty = jdata_set_page_dirty,
1226         .bmap = gfs2_bmap,
1227         .invalidatepage = gfs2_invalidatepage,
1228         .releasepage = gfs2_releasepage,
1229         .is_partially_uptodate = block_is_partially_uptodate,
1230         .error_remove_page = generic_error_remove_page,
1231 };
1232 
1233 void gfs2_set_aops(struct inode *inode)
1234 {
1235         struct gfs2_inode *ip = GFS2_I(inode);
1236 
1237         if (gfs2_is_writeback(ip))
1238                 inode->i_mapping->a_ops = &gfs2_writeback_aops;
1239         else if (gfs2_is_ordered(ip))
1240                 inode->i_mapping->a_ops = &gfs2_ordered_aops;
1241         else if (gfs2_is_jdata(ip))
1242                 inode->i_mapping->a_ops = &gfs2_jdata_aops;
1243         else
1244                 BUG();
1245 }
1246 
1247 

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