[GFS2] Remove unused zero_readpage from stuffed_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 #include <linux/lm_interface.h>
21
22 #include "gfs2.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);
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);
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);
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 /**
160  * stuffed_readpage - Fill in a Linux page with stuffed file data
161  * @ip: the inode
162  * @page: the page
163  *
164  * Returns: errno
165  */
166
167 static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
168 {
169         struct buffer_head *dibh;
170         void *kaddr;
171         int error;
172
173         BUG_ON(page->index);
174
175         error = gfs2_meta_inode_buffer(ip, &dibh);
176         if (error)
177                 return error;
178
179         kaddr = kmap_atomic(page, KM_USER0);
180         memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode),
181                ip->i_di.di_size);
182         memset(kaddr + ip->i_di.di_size, 0, PAGE_CACHE_SIZE - ip->i_di.di_size);
183         kunmap_atomic(kaddr, KM_USER0);
184
185         brelse(dibh);
186
187         SetPageUptodate(page);
188
189         return 0;
190 }
191
192
193 /**
194  * gfs2_readpage - readpage with locking
195  * @file: The file to read a page for. N.B. This may be NULL if we are
196  * reading an internal file.
197  * @page: The page to read
198  *
199  * Returns: errno
200  */
201
202 static int gfs2_readpage(struct file *file, struct page *page)
203 {
204         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
205         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
206         struct gfs2_file *gf = NULL;
207         struct gfs2_holder gh;
208         int error;
209         int do_unlock = 0;
210
211         if (likely(file != &gfs2_internal_file_sentinel)) {
212                 if (file) {
213                         gf = file->private_data;
214                         if (test_bit(GFF_EXLOCK, &gf->f_flags))
215                                 /* gfs2_sharewrite_nopage has grabbed the ip->i_gl already */
216                                 goto skip_lock;
217                 }
218                 gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME|LM_FLAG_TRY_1CB, &gh);
219                 do_unlock = 1;
220                 error = gfs2_glock_nq_m_atime(1, &gh);
221                 if (unlikely(error))
222                         goto out_unlock;
223         }
224
225 skip_lock:
226         if (gfs2_is_stuffed(ip)) {
227                 error = stuffed_readpage(ip, page);
228                 unlock_page(page);
229         } else
230                 error = mpage_readpage(page, gfs2_get_block);
231
232         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
233                 error = -EIO;
234
235         if (do_unlock) {
236                 gfs2_glock_dq_m(1, &gh);
237                 gfs2_holder_uninit(&gh);
238         }
239 out:
240         return error;
241 out_unlock:
242         if (error == GLR_TRYFAILED)
243                 error = AOP_TRUNCATED_PAGE;
244         unlock_page(page);
245         if (do_unlock)
246                 gfs2_holder_uninit(&gh);
247         goto out;
248 }
249
250 /**
251  * gfs2_readpages - Read a bunch of pages at once
252  *
253  * Some notes:
254  * 1. This is only for readahead, so we can simply ignore any things
255  *    which are slightly inconvenient (such as locking conflicts between
256  *    the page lock and the glock) and return having done no I/O. Its
257  *    obviously not something we'd want to do on too regular a basis.
258  *    Any I/O we ignore at this time will be done via readpage later.
259  * 2. We have to handle stuffed files here too.
260  * 3. mpage_readpages() does most of the heavy lifting in the common case.
261  * 4. gfs2_get_block() is relied upon to set BH_Boundary in the right places.
262  * 5. We use LM_FLAG_TRY_1CB here, effectively we then have lock-ahead as
263  *    well as read-ahead.
264  */
265 static int gfs2_readpages(struct file *file, struct address_space *mapping,
266                           struct list_head *pages, unsigned nr_pages)
267 {
268         struct inode *inode = mapping->host;
269         struct gfs2_inode *ip = GFS2_I(inode);
270         struct gfs2_sbd *sdp = GFS2_SB(inode);
271         struct gfs2_holder gh;
272         unsigned page_idx;
273         int ret;
274         int do_unlock = 0;
275
276         if (likely(file != &gfs2_internal_file_sentinel)) {
277                 if (file) {
278                         struct gfs2_file *gf = file->private_data;
279                         if (test_bit(GFF_EXLOCK, &gf->f_flags))
280                                 goto skip_lock;
281                 }
282                 gfs2_holder_init(ip->i_gl, LM_ST_SHARED,
283                                  LM_FLAG_TRY_1CB|GL_ATIME, &gh);
284                 do_unlock = 1;
285                 ret = gfs2_glock_nq_m_atime(1, &gh);
286                 if (ret == GLR_TRYFAILED)
287                         goto out_noerror;
288                 if (unlikely(ret))
289                         goto out_unlock;
290         }
291 skip_lock:
292         if (gfs2_is_stuffed(ip)) {
293                 struct pagevec lru_pvec;
294                 pagevec_init(&lru_pvec, 0);
295                 for (page_idx = 0; page_idx < nr_pages; page_idx++) {
296                         struct page *page = list_entry(pages->prev, struct page, lru);
297                         prefetchw(&page->flags);
298                         list_del(&page->lru);
299                         if (!add_to_page_cache(page, mapping,
300                                                page->index, GFP_KERNEL)) {
301                                 ret = stuffed_readpage(ip, page);
302                                 unlock_page(page);
303                                 if (!pagevec_add(&lru_pvec, page))
304                                          __pagevec_lru_add(&lru_pvec);
305                         } else {
306                                 page_cache_release(page);
307                         }
308                 }
309                 pagevec_lru_add(&lru_pvec);
310                 ret = 0;
311         } else {
312                 /* What we really want to do .... */
313                 ret = mpage_readpages(mapping, pages, nr_pages, gfs2_get_block);
314         }
315
316         if (do_unlock) {
317                 gfs2_glock_dq_m(1, &gh);
318                 gfs2_holder_uninit(&gh);
319         }
320 out:
321         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
322                 ret = -EIO;
323         return ret;
324 out_noerror:
325         ret = 0;
326 out_unlock:
327         if (do_unlock)
328                 gfs2_holder_uninit(&gh);
329         goto out;
330 }
331
332 /**
333  * gfs2_prepare_write - Prepare to write a page to a file
334  * @file: The file to write to
335  * @page: The page which is to be prepared for writing
336  * @from: From (byte range within page)
337  * @to: To (byte range within page)
338  *
339  * Returns: errno
340  */
341
342 static int gfs2_prepare_write(struct file *file, struct page *page,
343                               unsigned from, unsigned to)
344 {
345         struct gfs2_inode *ip = GFS2_I(page->mapping->host);
346         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
347         unsigned int data_blocks, ind_blocks, rblocks;
348         int alloc_required;
349         int error = 0;
350         loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + from;
351         loff_t end = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
352         struct gfs2_alloc *al;
353         unsigned int write_len = to - from;
354
355
356         gfs2_holder_init(ip->i_gl, LM_ST_EXCLUSIVE, GL_ATIME|LM_FLAG_TRY_1CB, &ip->i_gh);
357         error = gfs2_glock_nq_m_atime(1, &ip->i_gh);
358         if (unlikely(error)) {
359                 if (error == GLR_TRYFAILED)
360                         error = AOP_TRUNCATED_PAGE;
361                 goto out_uninit;
362         }
363
364         gfs2_write_calc_reserv(ip, write_len, &data_blocks, &ind_blocks);
365
366         error = gfs2_write_alloc_required(ip, pos, write_len, &alloc_required);
367         if (error)
368                 goto out_unlock;
369
370
371         ip->i_alloc.al_requested = 0;
372         if (alloc_required) {
373                 al = gfs2_alloc_get(ip);
374
375                 error = gfs2_quota_lock(ip, NO_QUOTA_CHANGE, NO_QUOTA_CHANGE);
376                 if (error)
377                         goto out_alloc_put;
378
379                 error = gfs2_quota_check(ip, ip->i_inode.i_uid, ip->i_inode.i_gid);
380                 if (error)
381                         goto out_qunlock;
382
383                 al->al_requested = data_blocks + ind_blocks;
384                 error = gfs2_inplace_reserve(ip);
385                 if (error)
386                         goto out_qunlock;
387         }
388
389         rblocks = RES_DINODE + ind_blocks;
390         if (gfs2_is_jdata(ip))
391                 rblocks += data_blocks ? data_blocks : 1;
392         if (ind_blocks || data_blocks)
393                 rblocks += RES_STATFS + RES_QUOTA;
394
395         error = gfs2_trans_begin(sdp, rblocks, 0);
396         if (error)
397                 goto out;
398
399         if (gfs2_is_stuffed(ip)) {
400                 if (end > sdp->sd_sb.sb_bsize - sizeof(struct gfs2_dinode)) {
401                         error = gfs2_unstuff_dinode(ip, page);
402                         if (error == 0)
403                                 goto prepare_write;
404                 } else if (!PageUptodate(page))
405                         error = stuffed_readpage(ip, page);
406                 goto out;
407         }
408
409 prepare_write:
410         error = block_prepare_write(page, from, to, gfs2_get_block);
411
412 out:
413         if (error) {
414                 gfs2_trans_end(sdp);
415                 if (alloc_required) {
416                         gfs2_inplace_release(ip);
417 out_qunlock:
418                         gfs2_quota_unlock(ip);
419 out_alloc_put:
420                         gfs2_alloc_put(ip);
421                 }
422 out_unlock:
423                 gfs2_glock_dq_m(1, &ip->i_gh);
424 out_uninit:
425                 gfs2_holder_uninit(&ip->i_gh);
426         }
427
428         return error;
429 }
430
431 /**
432  * gfs2_commit_write - Commit write to a file
433  * @file: The file to write to
434  * @page: The page containing the data
435  * @from: From (byte range within page)
436  * @to: To (byte range within page)
437  *
438  * Returns: errno
439  */
440
441 static int gfs2_commit_write(struct file *file, struct page *page,
442                              unsigned from, unsigned to)
443 {
444         struct inode *inode = page->mapping->host;
445         struct gfs2_inode *ip = GFS2_I(inode);
446         struct gfs2_sbd *sdp = GFS2_SB(inode);
447         int error = -EOPNOTSUPP;
448         struct buffer_head *dibh;
449         struct gfs2_alloc *al = &ip->i_alloc;
450         struct gfs2_dinode *di;
451
452         if (gfs2_assert_withdraw(sdp, gfs2_glock_is_locked_by_me(ip->i_gl)))
453                 goto fail_nounlock;
454
455         error = gfs2_meta_inode_buffer(ip, &dibh);
456         if (error)
457                 goto fail_endtrans;
458
459         gfs2_trans_add_bh(ip->i_gl, dibh, 1);
460         di = (struct gfs2_dinode *)dibh->b_data;
461
462         if (gfs2_is_stuffed(ip)) {
463                 u64 file_size;
464                 void *kaddr;
465
466                 file_size = ((u64)page->index << PAGE_CACHE_SHIFT) + to;
467
468                 kaddr = kmap_atomic(page, KM_USER0);
469                 memcpy(dibh->b_data + sizeof(struct gfs2_dinode) + from,
470                        kaddr + from, to - from);
471                 kunmap_atomic(kaddr, KM_USER0);
472
473                 SetPageUptodate(page);
474
475                 if (inode->i_size < file_size)
476                         i_size_write(inode, file_size);
477         } else {
478                 if (sdp->sd_args.ar_data == GFS2_DATA_ORDERED ||
479                     gfs2_is_jdata(ip))
480                         gfs2_page_add_databufs(ip, page, from, to);
481                 error = generic_commit_write(file, page, from, to);
482                 if (error)
483                         goto fail;
484         }
485
486         if (ip->i_di.di_size < inode->i_size) {
487                 ip->i_di.di_size = inode->i_size;
488                 di->di_size = cpu_to_be64(inode->i_size);
489         }
490
491         brelse(dibh);
492         gfs2_trans_end(sdp);
493         if (al->al_requested) {
494                 gfs2_inplace_release(ip);
495                 gfs2_quota_unlock(ip);
496                 gfs2_alloc_put(ip);
497         }
498         gfs2_glock_dq_m(1, &ip->i_gh);
499         gfs2_holder_uninit(&ip->i_gh);
500         return 0;
501
502 fail:
503         brelse(dibh);
504 fail_endtrans:
505         gfs2_trans_end(sdp);
506         if (al->al_requested) {
507                 gfs2_inplace_release(ip);
508                 gfs2_quota_unlock(ip);
509                 gfs2_alloc_put(ip);
510         }
511         gfs2_glock_dq_m(1, &ip->i_gh);
512         gfs2_holder_uninit(&ip->i_gh);
513 fail_nounlock:
514         ClearPageUptodate(page);
515         return error;
516 }
517
518 /**
519  * gfs2_bmap - Block map function
520  * @mapping: Address space info
521  * @lblock: The block to map
522  *
523  * Returns: The disk address for the block or 0 on hole or error
524  */
525
526 static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
527 {
528         struct gfs2_inode *ip = GFS2_I(mapping->host);
529         struct gfs2_holder i_gh;
530         sector_t dblock = 0;
531         int error;
532
533         error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
534         if (error)
535                 return 0;
536
537         if (!gfs2_is_stuffed(ip))
538                 dblock = generic_block_bmap(mapping, lblock, gfs2_get_block);
539
540         gfs2_glock_dq_uninit(&i_gh);
541
542         return dblock;
543 }
544
545 static void discard_buffer(struct gfs2_sbd *sdp, struct buffer_head *bh)
546 {
547         struct gfs2_bufdata *bd;
548
549         gfs2_log_lock(sdp);
550         bd = bh->b_private;
551         if (bd) {
552                 bd->bd_bh = NULL;
553                 bh->b_private = NULL;
554         }
555         gfs2_log_unlock(sdp);
556
557         lock_buffer(bh);
558         clear_buffer_dirty(bh);
559         bh->b_bdev = NULL;
560         clear_buffer_mapped(bh);
561         clear_buffer_req(bh);
562         clear_buffer_new(bh);
563         clear_buffer_delay(bh);
564         unlock_buffer(bh);
565 }
566
567 static void gfs2_invalidatepage(struct page *page, unsigned long offset)
568 {
569         struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
570         struct buffer_head *head, *bh, *next;
571         unsigned int curr_off = 0;
572
573         BUG_ON(!PageLocked(page));
574         if (!page_has_buffers(page))
575                 return;
576
577         bh = head = page_buffers(page);
578         do {
579                 unsigned int next_off = curr_off + bh->b_size;
580                 next = bh->b_this_page;
581
582                 if (offset <= curr_off)
583                         discard_buffer(sdp, bh);
584
585                 curr_off = next_off;
586                 bh = next;
587         } while (bh != head);
588
589         if (!offset)
590                 try_to_release_page(page, 0);
591
592         return;
593 }
594
595 static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
596                               const struct iovec *iov, loff_t offset,
597                               unsigned long nr_segs)
598 {
599         struct file *file = iocb->ki_filp;
600         struct inode *inode = file->f_mapping->host;
601         struct gfs2_inode *ip = GFS2_I(inode);
602         struct gfs2_holder gh;
603         int rv;
604
605         if (rw == READ)
606                 mutex_lock(&inode->i_mutex);
607         /*
608          * Shared lock, even if its a write, since we do no allocation
609          * on this path. All we need change is atime.
610          */
611         gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME, &gh);
612         rv = gfs2_glock_nq_m_atime(1, &gh);
613         if (rv)
614                 goto out;
615
616         if (offset > i_size_read(inode))
617                 goto out;
618
619         /*
620          * Should we return an error here? I can't see that O_DIRECT for
621          * a journaled file makes any sense. For now we'll silently fall
622          * back to buffered I/O, likewise we do the same for stuffed
623          * files since they are (a) small and (b) unaligned.
624          */
625         if (gfs2_is_jdata(ip))
626                 goto out;
627
628         if (gfs2_is_stuffed(ip))
629                 goto out;
630
631         rv = blockdev_direct_IO_own_locking(rw, iocb, inode,
632                                             inode->i_sb->s_bdev,
633                                             iov, offset, nr_segs,
634                                             gfs2_get_block_direct, NULL);
635 out:
636         gfs2_glock_dq_m(1, &gh);
637         gfs2_holder_uninit(&gh);
638         if (rw == READ)
639                 mutex_unlock(&inode->i_mutex);
640
641         return rv;
642 }
643
644 /**
645  * stuck_releasepage - We're stuck in gfs2_releasepage().  Print stuff out.
646  * @bh: the buffer we're stuck on
647  *
648  */
649
650 static void stuck_releasepage(struct buffer_head *bh)
651 {
652         struct inode *inode = bh->b_page->mapping->host;
653         struct gfs2_sbd *sdp = inode->i_sb->s_fs_info;
654         struct gfs2_bufdata *bd = bh->b_private;
655         struct gfs2_glock *gl;
656 static unsigned limit = 0;
657
658         if (limit > 3)
659                 return;
660         limit++;
661
662         fs_warn(sdp, "stuck in gfs2_releasepage() %p\n", inode);
663         fs_warn(sdp, "blkno = %llu, bh->b_count = %d\n",
664                 (unsigned long long)bh->b_blocknr, atomic_read(&bh->b_count));
665         fs_warn(sdp, "pinned = %u\n", buffer_pinned(bh));
666         fs_warn(sdp, "bh->b_private = %s\n", (bd) ? "!NULL" : "NULL");
667
668         if (!bd)
669                 return;
670
671         gl = bd->bd_gl;
672
673         fs_warn(sdp, "gl = (%u, %llu)\n",
674                 gl->gl_name.ln_type, (unsigned long long)gl->gl_name.ln_number);
675
676         fs_warn(sdp, "bd_list_tr = %s, bd_le.le_list = %s\n",
677                 (list_empty(&bd->bd_list_tr)) ? "no" : "yes",
678                 (list_empty(&bd->bd_le.le_list)) ? "no" : "yes");
679
680         if (gl->gl_ops == &gfs2_inode_glops) {
681                 struct gfs2_inode *ip = gl->gl_object;
682                 unsigned int x;
683
684                 if (!ip)
685                         return;
686
687                 fs_warn(sdp, "ip = %llu %llu\n",
688                         (unsigned long long)ip->i_num.no_formal_ino,
689                         (unsigned long long)ip->i_num.no_addr);
690
691                 for (x = 0; x < GFS2_MAX_META_HEIGHT; x++)
692                         fs_warn(sdp, "ip->i_cache[%u] = %s\n",
693                                 x, (ip->i_cache[x]) ? "!NULL" : "NULL");
694         }
695 }
696
697 /**
698  * gfs2_releasepage - free the metadata associated with a page
699  * @page: the page that's being released
700  * @gfp_mask: passed from Linux VFS, ignored by us
701  *
702  * Call try_to_free_buffers() if the buffers in this page can be
703  * released.
704  *
705  * Returns: 0
706  */
707
708 int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
709 {
710         struct inode *aspace = page->mapping->host;
711         struct gfs2_sbd *sdp = aspace->i_sb->s_fs_info;
712         struct buffer_head *bh, *head;
713         struct gfs2_bufdata *bd;
714         unsigned long t = jiffies + gfs2_tune_get(sdp, gt_stall_secs) * HZ;
715
716         if (!page_has_buffers(page))
717                 goto out;
718
719         head = bh = page_buffers(page);
720         do {
721                 while (atomic_read(&bh->b_count)) {
722                         if (!atomic_read(&aspace->i_writecount))
723                                 return 0;
724
725                         if (!(gfp_mask & __GFP_WAIT))
726                                 return 0;
727
728                         if (time_after_eq(jiffies, t)) {
729                                 stuck_releasepage(bh);
730                                 /* should we withdraw here? */
731                                 return 0;
732                         }
733
734                         yield();
735                 }
736
737                 gfs2_assert_warn(sdp, !buffer_pinned(bh));
738                 gfs2_assert_warn(sdp, !buffer_dirty(bh));
739
740                 gfs2_log_lock(sdp);
741                 bd = bh->b_private;
742                 if (bd) {
743                         gfs2_assert_warn(sdp, bd->bd_bh == bh);
744                         gfs2_assert_warn(sdp, list_empty(&bd->bd_list_tr));
745                         gfs2_assert_warn(sdp, !bd->bd_ail);
746                         bd->bd_bh = NULL;
747                         if (!list_empty(&bd->bd_le.le_list))
748                                 bd = NULL;
749                         bh->b_private = NULL;
750                 }
751                 gfs2_log_unlock(sdp);
752                 if (bd)
753                         kmem_cache_free(gfs2_bufdata_cachep, bd);
754
755                 bh = bh->b_this_page;
756         } while (bh != head);
757
758 out:
759         return try_to_free_buffers(page);
760 }
761
762 const struct address_space_operations gfs2_file_aops = {
763         .writepage = gfs2_writepage,
764         .readpage = gfs2_readpage,
765         .readpages = gfs2_readpages,
766         .sync_page = block_sync_page,
767         .prepare_write = gfs2_prepare_write,
768         .commit_write = gfs2_commit_write,
769         .bmap = gfs2_bmap,
770         .invalidatepage = gfs2_invalidatepage,
771         .releasepage = gfs2_releasepage,
772         .direct_IO = gfs2_direct_IO,
773 };
774