[GFS2] Fix for mmap() bug in readpage
[linux-2.6] / fs / gfs2 / ops_address.c
1 /*
2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
3  * Copyright (C) 2004-2006 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/gfs2_ondisk.h>
20
21 #include "gfs2.h"
22 #include "lm_interface.h"
23 #include "incore.h"
24 #include "bmap.h"
25 #include "glock.h"
26 #include "inode.h"
27 #include "log.h"
28 #include "meta_io.h"
29 #include "ops_address.h"
30 #include "quota.h"
31 #include "trans.h"
32 #include "rgrp.h"
33 #include "ops_file.h"
34 #include "util.h"
35 #include "glops.h"
36
37
38 static void gfs2_page_add_databufs(struct gfs2_inode *ip, struct page *page,
39                                    unsigned int from, unsigned int to)
40 {
41         struct buffer_head *head = page_buffers(page);
42         unsigned int bsize = head->b_size;
43         struct buffer_head *bh;
44         unsigned int start, end;
45
46         for (bh = head, start = 0; bh != head || !start;
47              bh = bh->b_this_page, start = end) {
48                 end = start + bsize;
49                 if (end <= from || start >= to)
50                         continue;
51                 gfs2_trans_add_bh(ip->i_gl, bh, 0);
52         }
53 }
54
55 /**
56  * gfs2_get_block - Fills in a buffer head with details about a block
57  * @inode: The inode
58  * @lblock: The block number to look up
59  * @bh_result: The buffer head to return the result in
60  * @create: Non-zero if we may add block to the file
61  *
62  * Returns: errno
63  */
64
65 int gfs2_get_block(struct inode *inode, sector_t lblock,
66                    struct buffer_head *bh_result, int create)
67 {
68         return gfs2_block_map(inode, lblock, create, bh_result, 32);
69 }
70
71 /**
72  * gfs2_get_block_noalloc - Fills in a buffer head with details about a block
73  * @inode: The inode
74  * @lblock: The block number to look up
75  * @bh_result: The buffer head to return the result in
76  * @create: Non-zero if we may add block to the file
77  *
78  * Returns: errno
79  */
80
81 static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock,
82                                   struct buffer_head *bh_result, int create)
83 {
84         int error;
85
86         error = gfs2_block_map(inode, lblock, 0, bh_result, 1);
87         if (error)
88                 return error;
89         if (bh_result->b_blocknr == 0)
90                 return -EIO;
91         return 0;
92 }
93
94 static int gfs2_get_block_direct(struct inode *inode, sector_t lblock,
95                                  struct buffer_head *bh_result, int create)
96 {
97         return gfs2_block_map(inode, lblock, 0, bh_result, 512);
98 }
99
100 /**
101  * gfs2_writepage - Write complete page
102  * @page: Page to write
103  *
104  * Returns: errno
105  *
106  * Some of this is copied from block_write_full_page() although we still
107  * call it to do most of the work.
108  */
109
110 static int gfs2_writepage(struct page *page, struct writeback_control *wbc)
111 {
112         struct inode *inode = page->mapping->host;
113         struct gfs2_inode *ip = GFS2_I(inode);
114         struct gfs2_sbd *sdp = GFS2_SB(inode);
115         loff_t i_size = i_size_read(inode);
116         pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
117         unsigned offset;
118         int error;
119         int done_trans = 0;
120
121         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl))) {
122                 unlock_page(page);
123                 return -EIO;
124         }
125         if (current->journal_info)
126                 goto out_ignore;
127
128         /* Is the page fully outside i_size? (truncate in progress) */
129         offset = i_size & (PAGE_CACHE_SIZE-1);
130         if (page->index > end_index || (page->index == end_index && !offset)) {
131                 page->mapping->a_ops->invalidatepage(page, 0);
132                 unlock_page(page);
133                 return 0; /* don't care */
134         }
135
136         if (sdp->sd_args.ar_data == GFS2_DATA_ORDERED || gfs2_is_jdata(ip)) {
137                 error = gfs2_trans_begin(sdp, RES_DINODE + 1, 0);
138                 if (error)
139                         goto out_ignore;
140                 if (!page_has_buffers(page)) {
141                         create_empty_buffers(page, inode->i_sb->s_blocksize,
142                                              (1 << BH_Dirty)|(1 << BH_Uptodate));
143                 }
144                 gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize-1);
145                 done_trans = 1;
146         }
147         error = block_write_full_page(page, gfs2_get_block_noalloc, wbc);
148         if (done_trans)
149                 gfs2_trans_end(sdp);
150         gfs2_meta_cache_flush(ip);
151         return error;
152
153 out_ignore:
154         redirty_page_for_writepage(wbc, page);
155         unlock_page(page);
156         return 0;
157 }
158
159 static int zero_readpage(struct page *page)
160 {
161         void *kaddr;
162
163         kaddr = kmap_atomic(page, KM_USER0);
164         memset(kaddr, 0, PAGE_CACHE_SIZE);
165         kunmap_atomic(page, KM_USER0);
166
167         SetPageUptodate(page);
168
169         return 0;
170 }
171
172 /**
173  * stuffed_readpage - Fill in a Linux page with stuffed file data
174  * @ip: the inode
175  * @page: the page
176  *
177  * Returns: errno
178  */
179
180 static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
181 {
182         struct buffer_head *dibh;
183         void *kaddr;
184         int error;
185
186         /* Only the first page of a stuffed file might contain data */
187         if (unlikely(page->index))
188                 return zero_readpage(page);
189
190         error = gfs2_meta_inode_buffer(ip, &dibh);
191         if (error)
192                 return error;
193
194         kaddr = kmap_atomic(page, KM_USER0);
195         memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode),
196                ip->i_di.di_size);
197         memset(kaddr + ip->i_di.di_size, 0, PAGE_CACHE_SIZE - ip->i_di.di_size);
198         kunmap_atomic(page, KM_USER0);
199
200         brelse(dibh);
201
202         SetPageUptodate(page);
203
204         return 0;
205 }
206
207
208 /**
209  * gfs2_readpage - readpage with locking
210  * @file: The file to read a page for. N.B. This may be NULL if we are
211  * reading an internal file.
212  * @page: The page to read
213  *
214  * Returns: errno
215  */
216
217 static int gfs2_readpage(struct file *file, struct page *page)
218 {
219         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
220         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
221         struct gfs2_file *gf = NULL;
222         struct gfs2_holder gh;
223         int error;
224         int do_unlock = 0;
225
226         if (likely(file != &gfs2_internal_file_sentinel)) {
227                 if (file) {
228                         gf = file->private_data;
229                         if (test_bit(GFF_EXLOCK, &gf->f_flags))
230                                 /* gfs2_sharewrite_nopage has grabbed the ip->i_gl already */
231                                 goto skip_lock;
232                 }
233                 gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME|GL_AOP, &gh);
234                 do_unlock = 1;
235                 error = gfs2_glock_nq_m_atime(1, &gh);
236                 if (unlikely(error))
237                         goto out_unlock;
238         }
239
240 skip_lock:
241         if (gfs2_is_stuffed(ip)) {
242                 error = stuffed_readpage(ip, page);
243                 unlock_page(page);
244         } else
245                 error = mpage_readpage(page, gfs2_get_block);
246
247         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
248                 error = -EIO;
249
250         if (gf && !test_bit(GFF_EXLOCK, &gf->f_flags) &&
251             file != &gfs2_internal_file_sentinel) {
252                 gfs2_glock_dq_m(1, &gh);
253                 gfs2_holder_uninit(&gh);
254         }
255 out:
256         return error;
257 out_unlock:
258         unlock_page(page);
259         if (do_unlock)
260                 gfs2_holder_uninit(&gh);
261         goto out;
262 }
263
264 /**
265  * gfs2_readpages - Read a bunch of pages at once
266  *
267  * Some notes:
268  * 1. This is only for readahead, so we can simply ignore any things
269  *    which are slightly inconvenient (such as locking conflicts between
270  *    the page lock and the glock) and return having done no I/O. Its
271  *    obviously not something we'd want to do on too regular a basis.
272  *    Any I/O we ignore at this time will be done via readpage later.
273  * 2. We have to handle stuffed files here too.
274  * 3. mpage_readpages() does most of the heavy lifting in the common case.
275  * 4. gfs2_get_block() is relied upon to set BH_Boundary in the right places.
276  * 5. We use LM_FLAG_TRY_1CB here, effectively we then have lock-ahead as
277  *    well as read-ahead.
278  */
279 static int gfs2_readpages(struct file *file, struct address_space *mapping,
280                           struct list_head *pages, unsigned nr_pages)
281 {
282         struct inode *inode = mapping->host;
283         struct gfs2_inode *ip = GFS2_I(inode);
284         struct gfs2_sbd *sdp = GFS2_SB(inode);
285         struct gfs2_holder gh;
286         unsigned page_idx;
287         int ret;
288         int do_unlock = 0;
289
290         if (likely(file != &gfs2_internal_file_sentinel)) {
291                 if (file) {
292                         struct gfs2_file *gf = file->private_data;
293                         if (test_bit(GFF_EXLOCK, &gf->f_flags))
294                                 goto skip_lock;
295                 }
296                 gfs2_holder_init(ip->i_gl, LM_ST_SHARED,
297                                  LM_FLAG_TRY_1CB|GL_ATIME|GL_AOP, &gh);
298                 do_unlock = 1;
299                 ret = gfs2_glock_nq_m_atime(1, &gh);
300                 if (ret == GLR_TRYFAILED) 
301                         goto out_noerror;
302                 if (unlikely(ret))
303                         goto out_unlock;
304         }
305 skip_lock:
306         if (gfs2_is_stuffed(ip)) {
307                 struct pagevec lru_pvec;
308                 pagevec_init(&lru_pvec, 0);
309                 for (page_idx = 0; page_idx < nr_pages; page_idx++) {
310                         struct page *page = list_entry(pages->prev, struct page, lru);
311                         prefetchw(&page->flags);
312                         list_del(&page->lru);
313                         if (!add_to_page_cache(page, mapping,
314                                                page->index, GFP_KERNEL)) {
315                                 ret = stuffed_readpage(ip, page);
316                                 unlock_page(page);
317                                 if (!pagevec_add(&lru_pvec, page))
318                                          __pagevec_lru_add(&lru_pvec);
319                         } else {
320                                 page_cache_release(page);
321                         }
322                 }
323                 pagevec_lru_add(&lru_pvec);
324                 ret = 0;
325         } else {
326                 /* What we really want to do .... */
327                 ret = mpage_readpages(mapping, pages, nr_pages, gfs2_get_block);
328         }
329
330         if (do_unlock) {
331                 gfs2_glock_dq_m(1, &gh);
332                 gfs2_holder_uninit(&gh);
333         }
334 out:
335         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
336                 ret = -EIO;
337         return ret;
338 out_noerror:
339         ret = 0;
340 out_unlock:
341         /* unlock all pages, we can't do any I/O right now */
342         for (page_idx = 0; page_idx < nr_pages; page_idx++) {
343                 struct page *page = list_entry(pages->prev, struct page, lru);
344                 list_del(&page->lru);
345                 unlock_page(page);
346                 page_cache_release(page);
347         }
348         if (do_unlock)
349                 gfs2_holder_uninit(&gh);
350         goto out;
351 }
352
353 /**
354  * gfs2_prepare_write - Prepare to write a page to a file
355  * @file: The file to write to
356  * @page: The page which is to be prepared for writing
357  * @from: From (byte range within page)
358  * @to: To (byte range within page)
359  *
360  * Returns: errno
361  */
362
363 static int gfs2_prepare_write(struct file *file, struct page *page,
364                               unsigned from, unsigned to)
365 {
366         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
367         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
368         unsigned int data_blocks, ind_blocks, rblocks;
369         int alloc_required;
370         int error = 0;
371         loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + from;
372         loff_t end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
373         struct gfs2_alloc *al;
374
375         gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_ATIME|GL_AOP, &ip->i_gh);
376         error = gfs2_glock_nq_m_atime(1, &ip->i_gh);
377         if (error)
378                 goto out_uninit;
379
380         gfs2_write_calc_reserv(ip, to - from, &data_blocks, &ind_blocks);
381
382         error = gfs2_write_alloc_required(ip, pos, from - to, &alloc_required);
383         if (error)
384                 goto out_unlock;
385
386
387         if (alloc_required) {
388                 al = gfs2_alloc_get(ip);
389
390                 error = gfs2_quota_lock(ip, NO_QUOTA_CHANGE, NO_QUOTA_CHANGE);
391                 if (error)
392                         goto out_alloc_put;
393
394                 error = gfs2_quota_check(ip, ip->i_di.di_uid, ip->i_di.di_gid);
395                 if (error)
396                         goto out_qunlock;
397
398                 al->al_requested = data_blocks + ind_blocks;
399                 error = gfs2_inplace_reserve(ip);
400                 if (error)
401                         goto out_qunlock;
402         }
403
404         rblocks = RES_DINODE + ind_blocks;
405         if (gfs2_is_jdata(ip))
406                 rblocks += data_blocks ? data_blocks : 1;
407         if (ind_blocks || data_blocks)
408                 rblocks += RES_STATFS + RES_QUOTA;
409
410         error = gfs2_trans_begin(sdp, rblocks, 0);
411         if (error)
412                 goto out;
413
414         if (gfs2_is_stuffed(ip)) {
415                 if (end > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
416                         error = gfs2_unstuff_dinode(ip, page);
417                         if (error == 0)
418                                 goto prepare_write;
419                 } else if (!PageUptodate(page))
420                         error = stuffed_readpage(ip, page);
421                 goto out;
422         }
423
424 prepare_write:
425         error = block_prepare_write(page, from, to, gfs2_get_block);
426
427 out:
428         if (error) {
429                 gfs2_trans_end(sdp);
430                 if (alloc_required) {
431                         gfs2_inplace_release(ip);
432 out_qunlock:
433                         gfs2_quota_unlock(ip);
434 out_alloc_put:
435                         gfs2_alloc_put(ip);
436                 }
437 out_unlock:
438                 gfs2_glock_dq_m(1, &ip->i_gh);
439 out_uninit:
440                 gfs2_holder_uninit(&ip->i_gh);
441         }
442
443         return error;
444 }
445
446 /**
447  * gfs2_commit_write - Commit write to a file
448  * @file: The file to write to
449  * @page: The page containing the data
450  * @from: From (byte range within page)
451  * @to: To (byte range within page)
452  *
453  * Returns: errno
454  */
455
456 static int gfs2_commit_write(struct file *file, struct page *page,
457                              unsigned from, unsigned to)
458 {
459         struct inode *inode = page->mapping->host;
460         struct gfs2_inode *ip = GFS2_I(inode);
461         struct gfs2_sbd *sdp = GFS2_SB(inode);
462         int error = -EOPNOTSUPP;
463         struct buffer_head *dibh;
464         struct gfs2_alloc *al = &ip->i_alloc;;
465
466         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_locked_by_me(ip->i_gl)))
467                 goto fail_nounlock;
468
469         error = gfs2_meta_inode_buffer(ip, &dibh);
470         if (error)
471                 goto fail_endtrans;
472
473         gfs2_trans_add_bh(ip->i_gl, dibh, 1);
474
475         if (gfs2_is_stuffed(ip)) {
476                 u64 file_size;
477                 void *kaddr;
478
479                 file_size = ((u64)page->index << PAGE_CACHE_SHIFT) + to;
480
481                 kaddr = kmap_atomic(page, KM_USER0);
482                 memcpy(dibh->b_data + sizeof(struct gfs2_dinode) + from,
483                        kaddr + from, to - from);
484                 kunmap_atomic(page, KM_USER0);
485
486                 SetPageUptodate(page);
487
488                 if (inode->i_size < file_size)
489                         i_size_write(inode, file_size);
490         } else {
491                 if (sdp->sd_args.ar_data == GFS2_DATA_ORDERED ||
492                     gfs2_is_jdata(ip))
493                         gfs2_page_add_databufs(ip, page, from, to);
494                 error = generic_commit_write(file, page, from, to);
495                 if (error)
496                         goto fail;
497         }
498
499         if (ip->i_di.di_size < inode->i_size)
500                 ip->i_di.di_size = inode->i_size;
501
502         gfs2_dinode_out(&ip->i_di, dibh->b_data);
503         brelse(dibh);
504         gfs2_trans_end(sdp);
505         if (al->al_requested) {
506                 gfs2_inplace_release(ip);
507                 gfs2_quota_unlock(ip);
508                 gfs2_alloc_put(ip);
509         }
510         gfs2_glock_dq_m(1, &ip->i_gh);
511         gfs2_holder_uninit(&ip->i_gh);
512         return 0;
513
514 fail:
515         brelse(dibh);
516 fail_endtrans:
517         gfs2_trans_end(sdp);
518         if (al->al_requested) {
519                 gfs2_inplace_release(ip);
520                 gfs2_quota_unlock(ip);
521                 gfs2_alloc_put(ip);
522         }
523         gfs2_glock_dq_m(1, &ip->i_gh);
524         gfs2_holder_uninit(&ip->i_gh);
525 fail_nounlock:
526         ClearPageUptodate(page);
527         return error;
528 }
529
530 /**
531  * gfs2_bmap - Block map function
532  * @mapping: Address space info
533  * @lblock: The block to map
534  *
535  * Returns: The disk address for the block or 0 on hole or error
536  */
537
538 static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
539 {
540         struct gfs2_inode *ip = GFS2_I(mapping->host);
541         struct gfs2_holder i_gh;
542         sector_t dblock = 0;
543         int error;
544
545         error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
546         if (error)
547                 return 0;
548
549         if (!gfs2_is_stuffed(ip))
550                 dblock = generic_block_bmap(mapping, lblock, gfs2_get_block);
551
552         gfs2_glock_dq_uninit(&i_gh);
553
554         return dblock;
555 }
556
557 static void discard_buffer(struct gfs2_sbd *sdp, struct buffer_head *bh)
558 {
559         struct gfs2_bufdata *bd;
560
561         gfs2_log_lock(sdp);
562         bd = bh->b_private;
563         if (bd) {
564                 bd->bd_bh = NULL;
565                 bh->b_private = NULL;
566         }
567         gfs2_log_unlock(sdp);
568
569         lock_buffer(bh);
570         clear_buffer_dirty(bh);
571         bh->b_bdev = NULL;
572         clear_buffer_mapped(bh);
573         clear_buffer_req(bh);
574         clear_buffer_new(bh);
575         clear_buffer_delay(bh);
576         unlock_buffer(bh);
577 }
578
579 static void gfs2_invalidatepage(struct page *page, unsigned long offset)
580 {
581         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
582         struct buffer_head *head, *bh, *next;
583         unsigned int curr_off = 0;
584
585         BUG_ON(!PageLocked(page));
586         if (!page_has_buffers(page))
587                 return;
588
589         bh = head = page_buffers(page);
590         do {
591                 unsigned int next_off = curr_off + bh->b_size;
592                 next = bh->b_this_page;
593
594                 if (offset <= curr_off)
595                         discard_buffer(sdp, bh);
596
597                 curr_off = next_off;
598                 bh = next;
599         } while (bh != head);
600
601         if (!offset)
602                 try_to_release_page(page, 0);
603
604         return;
605 }
606
607 static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
608                               const struct iovec *iov, loff_t offset,
609                               unsigned long nr_segs)
610 {
611         struct file *file = iocb->ki_filp;
612         struct inode *inode = file->f_mapping->host;
613         struct gfs2_inode *ip = GFS2_I(inode);
614         struct gfs2_holder gh;
615         int rv;
616
617         if (rw == READ)
618                 mutex_lock(&inode->i_mutex);
619         /*
620          * Shared lock, even if its a write, since we do no allocation
621          * on this path. All we need change is atime.
622          */
623         gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME, &gh);
624         rv = gfs2_glock_nq_m_atime(1, &gh);
625         if (rv)
626                 goto out;
627
628         if (offset > i_size_read(inode))
629                 goto out;
630
631         /*
632          * Should we return an error here? I can't see that O_DIRECT for
633          * a journaled file makes any sense. For now we'll silently fall
634          * back to buffered I/O, likewise we do the same for stuffed
635          * files since they are (a) small and (b) unaligned.
636          */
637         if (gfs2_is_jdata(ip))
638                 goto out;
639
640         if (gfs2_is_stuffed(ip))
641                 goto out;
642
643         rv = blockdev_direct_IO_own_locking(rw, iocb, inode,
644                                             inode->i_sb->s_bdev,
645                                             iov, offset, nr_segs,
646                                             gfs2_get_block_direct, NULL);
647 out:
648         gfs2_glock_dq_m(1, &gh);
649         gfs2_holder_uninit(&gh);
650         if (rw == READ)
651                 mutex_unlock(&inode->i_mutex);
652
653         return rv;
654 }
655
656 /**
657  * stuck_releasepage - We're stuck in gfs2_releasepage().  Print stuff out.
658  * @bh: the buffer we're stuck on
659  *
660  */
661
662 static void stuck_releasepage(struct buffer_head *bh)
663 {
664         struct inode *inode = bh->b_page->mapping->host;
665         struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
666         struct gfs2_bufdata *bd = bh->b_private;
667         struct gfs2_glock *gl;
668 static unsigned limit = 0;
669
670         if (limit > 3)
671                 return;
672         limit++;
673
674         fs_warn(sdp, "stuck in gfs2_releasepage() %p\n", inode);
675         fs_warn(sdp, "blkno = %llu, bh->b_count = %d\n",
676                 (unsigned long long)bh->b_blocknr, atomic_read(&bh->b_count));
677         fs_warn(sdp, "pinned = %u\n", buffer_pinned(bh));
678         fs_warn(sdp, "bh->b_private = %s\n", (bd) ? "!NULL" : "NULL");
679
680         if (!bd)
681                 return;
682
683         gl = bd->bd_gl;
684
685         fs_warn(sdp, "gl = (%u, %llu)\n", 
686                 gl->gl_name.ln_type, (unsigned long long)gl->gl_name.ln_number);
687
688         fs_warn(sdp, "bd_list_tr = %s, bd_le.le_list = %s\n",
689                 (list_empty(&bd->bd_list_tr)) ? "no" : "yes",
690                 (list_empty(&bd->bd_le.le_list)) ? "no" : "yes");
691
692         if (gl->gl_ops == &gfs2_inode_glops) {
693                 struct gfs2_inode *ip = gl->gl_object;
694                 unsigned int x;
695
696                 if (!ip)
697                         return;
698
699                 fs_warn(sdp, "ip = %llu %llu\n",
700                         (unsigned long long)ip->i_num.no_formal_ino,
701                         (unsigned long long)ip->i_num.no_addr);
702
703                 for (x = 0; x < GFS2_MAX_META_HEIGHT; x++)
704                         fs_warn(sdp, "ip->i_cache[%u] = %s\n",
705                                 x, (ip->i_cache[x]) ? "!NULL" : "NULL");
706         }
707 }
708
709 /**
710  * gfs2_releasepage - free the metadata associated with a page
711  * @page: the page that's being released
712  * @gfp_mask: passed from Linux VFS, ignored by us
713  *
714  * Call try_to_free_buffers() if the buffers in this page can be
715  * released.
716  *
717  * Returns: 0
718  */
719
720 int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
721 {
722         struct inode *aspace = page->mapping->host;
723         struct gfs2_sbd *sdp = aspace->i_sb->s_fs_info;
724         struct buffer_head *bh, *head;
725         struct gfs2_bufdata *bd;
726         unsigned long t = jiffies + gfs2_tune_get(sdp, gt_stall_secs) * HZ;
727
728         if (!page_has_buffers(page))
729                 goto out;
730
731         head = bh = page_buffers(page);
732         do {
733                 while (atomic_read(&bh->b_count)) {
734                         if (!atomic_read(&aspace->i_writecount))
735                                 return 0;
736
737                         if (time_after_eq(jiffies, t)) {
738                                 stuck_releasepage(bh);
739                                 /* should we withdraw here? */
740                                 return 0;
741                         }
742
743                         yield();
744                 }
745
746                 gfs2_assert_warn(sdp, !buffer_pinned(bh));
747                 gfs2_assert_warn(sdp, !buffer_dirty(bh));
748
749                 gfs2_log_lock(sdp);
750                 bd = bh->b_private;
751                 if (bd) {
752                         gfs2_assert_warn(sdp, bd->bd_bh == bh);
753                         gfs2_assert_warn(sdp, list_empty(&bd->bd_list_tr));
754                         gfs2_assert_warn(sdp, !bd->bd_ail);
755                         bd->bd_bh = NULL;
756                         if (!list_empty(&bd->bd_le.le_list))
757                                 bd = NULL;
758                         bh->b_private = NULL;
759                 }
760                 gfs2_log_unlock(sdp);
761                 if (bd)
762                         kmem_cache_free(gfs2_bufdata_cachep, bd);
763
764                 bh = bh->b_this_page;
765         } while (bh != head);
766
767 out:
768         return try_to_free_buffers(page);
769 }
770
771 const struct address_space_operations gfs2_file_aops = {
772         .writepage = gfs2_writepage,
773         .readpage = gfs2_readpage,
774         .readpages = gfs2_readpages,
775         .sync_page = block_sync_page,
776         .prepare_write = gfs2_prepare_write,
777         .commit_write = gfs2_commit_write,
778         .bmap = gfs2_bmap,
779         .invalidatepage = gfs2_invalidatepage,
780         .releasepage = gfs2_releasepage,
781         .direct_IO = gfs2_direct_IO,
782 };
783