Merge branch 'for-linus' of git://git.o-hand.com/linux-rpurdie-leds
[linux-2.6] / fs / ocfs2 / aops.c
1 /* -*- mode: c; c-basic-offset: 8; -*-
2  * vim: noexpandtab sw=8 ts=8 sts=0:
3  *
4  * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public
8  * License as published by the Free Software Foundation; either
9  * version 2 of the License, or (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14  * General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public
17  * License along with this program; if not, write to the
18  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19  * Boston, MA 021110-1307, USA.
20  */
21
22 #include <linux/fs.h>
23 #include <linux/slab.h>
24 #include <linux/highmem.h>
25 #include <linux/pagemap.h>
26 #include <asm/byteorder.h>
27 #include <linux/swap.h>
28 #include <linux/pipe_fs_i.h>
29
30 #define MLOG_MASK_PREFIX ML_FILE_IO
31 #include <cluster/masklog.h>
32
33 #include "ocfs2.h"
34
35 #include "alloc.h"
36 #include "aops.h"
37 #include "dlmglue.h"
38 #include "extent_map.h"
39 #include "file.h"
40 #include "inode.h"
41 #include "journal.h"
42 #include "suballoc.h"
43 #include "super.h"
44 #include "symlink.h"
45
46 #include "buffer_head_io.h"
47
48 static int ocfs2_symlink_get_block(struct inode *inode, sector_t iblock,
49                                    struct buffer_head *bh_result, int create)
50 {
51         int err = -EIO;
52         int status;
53         struct ocfs2_dinode *fe = NULL;
54         struct buffer_head *bh = NULL;
55         struct buffer_head *buffer_cache_bh = NULL;
56         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
57         void *kaddr;
58
59         mlog_entry("(0x%p, %llu, 0x%p, %d)\n", inode,
60                    (unsigned long long)iblock, bh_result, create);
61
62         BUG_ON(ocfs2_inode_is_fast_symlink(inode));
63
64         if ((iblock << inode->i_sb->s_blocksize_bits) > PATH_MAX + 1) {
65                 mlog(ML_ERROR, "block offset > PATH_MAX: %llu",
66                      (unsigned long long)iblock);
67                 goto bail;
68         }
69
70         status = ocfs2_read_block(OCFS2_SB(inode->i_sb),
71                                   OCFS2_I(inode)->ip_blkno,
72                                   &bh, OCFS2_BH_CACHED, inode);
73         if (status < 0) {
74                 mlog_errno(status);
75                 goto bail;
76         }
77         fe = (struct ocfs2_dinode *) bh->b_data;
78
79         if (!OCFS2_IS_VALID_DINODE(fe)) {
80                 mlog(ML_ERROR, "Invalid dinode #%llu: signature = %.*s\n",
81                      (unsigned long long)le64_to_cpu(fe->i_blkno), 7,
82                      fe->i_signature);
83                 goto bail;
84         }
85
86         if ((u64)iblock >= ocfs2_clusters_to_blocks(inode->i_sb,
87                                                     le32_to_cpu(fe->i_clusters))) {
88                 mlog(ML_ERROR, "block offset is outside the allocated size: "
89                      "%llu\n", (unsigned long long)iblock);
90                 goto bail;
91         }
92
93         /* We don't use the page cache to create symlink data, so if
94          * need be, copy it over from the buffer cache. */
95         if (!buffer_uptodate(bh_result) && ocfs2_inode_is_new(inode)) {
96                 u64 blkno = le64_to_cpu(fe->id2.i_list.l_recs[0].e_blkno) +
97                             iblock;
98                 buffer_cache_bh = sb_getblk(osb->sb, blkno);
99                 if (!buffer_cache_bh) {
100                         mlog(ML_ERROR, "couldn't getblock for symlink!\n");
101                         goto bail;
102                 }
103
104                 /* we haven't locked out transactions, so a commit
105                  * could've happened. Since we've got a reference on
106                  * the bh, even if it commits while we're doing the
107                  * copy, the data is still good. */
108                 if (buffer_jbd(buffer_cache_bh)
109                     && ocfs2_inode_is_new(inode)) {
110                         kaddr = kmap_atomic(bh_result->b_page, KM_USER0);
111                         if (!kaddr) {
112                                 mlog(ML_ERROR, "couldn't kmap!\n");
113                                 goto bail;
114                         }
115                         memcpy(kaddr + (bh_result->b_size * iblock),
116                                buffer_cache_bh->b_data,
117                                bh_result->b_size);
118                         kunmap_atomic(kaddr, KM_USER0);
119                         set_buffer_uptodate(bh_result);
120                 }
121                 brelse(buffer_cache_bh);
122         }
123
124         map_bh(bh_result, inode->i_sb,
125                le64_to_cpu(fe->id2.i_list.l_recs[0].e_blkno) + iblock);
126
127         err = 0;
128
129 bail:
130         if (bh)
131                 brelse(bh);
132
133         mlog_exit(err);
134         return err;
135 }
136
137 static int ocfs2_get_block(struct inode *inode, sector_t iblock,
138                            struct buffer_head *bh_result, int create)
139 {
140         int err = 0;
141         unsigned int ext_flags;
142         u64 p_blkno, past_eof;
143         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
144
145         mlog_entry("(0x%p, %llu, 0x%p, %d)\n", inode,
146                    (unsigned long long)iblock, bh_result, create);
147
148         if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_SYSTEM_FILE)
149                 mlog(ML_NOTICE, "get_block on system inode 0x%p (%lu)\n",
150                      inode, inode->i_ino);
151
152         if (S_ISLNK(inode->i_mode)) {
153                 /* this always does I/O for some reason. */
154                 err = ocfs2_symlink_get_block(inode, iblock, bh_result, create);
155                 goto bail;
156         }
157
158         err = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno, NULL,
159                                           &ext_flags);
160         if (err) {
161                 mlog(ML_ERROR, "Error %d from get_blocks(0x%p, %llu, 1, "
162                      "%llu, NULL)\n", err, inode, (unsigned long long)iblock,
163                      (unsigned long long)p_blkno);
164                 goto bail;
165         }
166
167         /*
168          * ocfs2 never allocates in this function - the only time we
169          * need to use BH_New is when we're extending i_size on a file
170          * system which doesn't support holes, in which case BH_New
171          * allows block_prepare_write() to zero.
172          */
173         mlog_bug_on_msg(create && p_blkno == 0 && ocfs2_sparse_alloc(osb),
174                         "ino %lu, iblock %llu\n", inode->i_ino,
175                         (unsigned long long)iblock);
176
177         /* Treat the unwritten extent as a hole for zeroing purposes. */
178         if (p_blkno && !(ext_flags & OCFS2_EXT_UNWRITTEN))
179                 map_bh(bh_result, inode->i_sb, p_blkno);
180
181         if (!ocfs2_sparse_alloc(osb)) {
182                 if (p_blkno == 0) {
183                         err = -EIO;
184                         mlog(ML_ERROR,
185                              "iblock = %llu p_blkno = %llu blkno=(%llu)\n",
186                              (unsigned long long)iblock,
187                              (unsigned long long)p_blkno,
188                              (unsigned long long)OCFS2_I(inode)->ip_blkno);
189                         mlog(ML_ERROR, "Size %llu, clusters %u\n", (unsigned long long)i_size_read(inode), OCFS2_I(inode)->ip_clusters);
190                         dump_stack();
191                 }
192
193                 past_eof = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));
194                 mlog(0, "Inode %lu, past_eof = %llu\n", inode->i_ino,
195                      (unsigned long long)past_eof);
196
197                 if (create && (iblock >= past_eof))
198                         set_buffer_new(bh_result);
199         }
200
201 bail:
202         if (err < 0)
203                 err = -EIO;
204
205         mlog_exit(err);
206         return err;
207 }
208
209 static int ocfs2_readpage(struct file *file, struct page *page)
210 {
211         struct inode *inode = page->mapping->host;
212         loff_t start = (loff_t)page->index << PAGE_CACHE_SHIFT;
213         int ret, unlock = 1;
214
215         mlog_entry("(0x%p, %lu)\n", file, (page ? page->index : 0));
216
217         ret = ocfs2_meta_lock_with_page(inode, NULL, 0, page);
218         if (ret != 0) {
219                 if (ret == AOP_TRUNCATED_PAGE)
220                         unlock = 0;
221                 mlog_errno(ret);
222                 goto out;
223         }
224
225         if (down_read_trylock(&OCFS2_I(inode)->ip_alloc_sem) == 0) {
226                 ret = AOP_TRUNCATED_PAGE;
227                 goto out_meta_unlock;
228         }
229
230         /*
231          * i_size might have just been updated as we grabed the meta lock.  We
232          * might now be discovering a truncate that hit on another node.
233          * block_read_full_page->get_block freaks out if it is asked to read
234          * beyond the end of a file, so we check here.  Callers
235          * (generic_file_read, vm_ops->fault) are clever enough to check i_size
236          * and notice that the page they just read isn't needed.
237          *
238          * XXX sys_readahead() seems to get that wrong?
239          */
240         if (start >= i_size_read(inode)) {
241                 zero_user_page(page, 0, PAGE_SIZE, KM_USER0);
242                 SetPageUptodate(page);
243                 ret = 0;
244                 goto out_alloc;
245         }
246
247         ret = ocfs2_data_lock_with_page(inode, 0, page);
248         if (ret != 0) {
249                 if (ret == AOP_TRUNCATED_PAGE)
250                         unlock = 0;
251                 mlog_errno(ret);
252                 goto out_alloc;
253         }
254
255         ret = block_read_full_page(page, ocfs2_get_block);
256         unlock = 0;
257
258         ocfs2_data_unlock(inode, 0);
259 out_alloc:
260         up_read(&OCFS2_I(inode)->ip_alloc_sem);
261 out_meta_unlock:
262         ocfs2_meta_unlock(inode, 0);
263 out:
264         if (unlock)
265                 unlock_page(page);
266         mlog_exit(ret);
267         return ret;
268 }
269
270 /* Note: Because we don't support holes, our allocation has
271  * already happened (allocation writes zeros to the file data)
272  * so we don't have to worry about ordered writes in
273  * ocfs2_writepage.
274  *
275  * ->writepage is called during the process of invalidating the page cache
276  * during blocked lock processing.  It can't block on any cluster locks
277  * to during block mapping.  It's relying on the fact that the block
278  * mapping can't have disappeared under the dirty pages that it is
279  * being asked to write back.
280  */
281 static int ocfs2_writepage(struct page *page, struct writeback_control *wbc)
282 {
283         int ret;
284
285         mlog_entry("(0x%p)\n", page);
286
287         ret = block_write_full_page(page, ocfs2_get_block, wbc);
288
289         mlog_exit(ret);
290
291         return ret;
292 }
293
294 /*
295  * This is called from ocfs2_write_zero_page() which has handled it's
296  * own cluster locking and has ensured allocation exists for those
297  * blocks to be written.
298  */
299 int ocfs2_prepare_write_nolock(struct inode *inode, struct page *page,
300                                unsigned from, unsigned to)
301 {
302         int ret;
303
304         down_read(&OCFS2_I(inode)->ip_alloc_sem);
305
306         ret = block_prepare_write(page, from, to, ocfs2_get_block);
307
308         up_read(&OCFS2_I(inode)->ip_alloc_sem);
309
310         return ret;
311 }
312
313 /* Taken from ext3. We don't necessarily need the full blown
314  * functionality yet, but IMHO it's better to cut and paste the whole
315  * thing so we can avoid introducing our own bugs (and easily pick up
316  * their fixes when they happen) --Mark */
317 int walk_page_buffers(  handle_t *handle,
318                         struct buffer_head *head,
319                         unsigned from,
320                         unsigned to,
321                         int *partial,
322                         int (*fn)(      handle_t *handle,
323                                         struct buffer_head *bh))
324 {
325         struct buffer_head *bh;
326         unsigned block_start, block_end;
327         unsigned blocksize = head->b_size;
328         int err, ret = 0;
329         struct buffer_head *next;
330
331         for (   bh = head, block_start = 0;
332                 ret == 0 && (bh != head || !block_start);
333                 block_start = block_end, bh = next)
334         {
335                 next = bh->b_this_page;
336                 block_end = block_start + blocksize;
337                 if (block_end <= from || block_start >= to) {
338                         if (partial && !buffer_uptodate(bh))
339                                 *partial = 1;
340                         continue;
341                 }
342                 err = (*fn)(handle, bh);
343                 if (!ret)
344                         ret = err;
345         }
346         return ret;
347 }
348
349 handle_t *ocfs2_start_walk_page_trans(struct inode *inode,
350                                                          struct page *page,
351                                                          unsigned from,
352                                                          unsigned to)
353 {
354         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
355         handle_t *handle = NULL;
356         int ret = 0;
357
358         handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
359         if (!handle) {
360                 ret = -ENOMEM;
361                 mlog_errno(ret);
362                 goto out;
363         }
364
365         if (ocfs2_should_order_data(inode)) {
366                 ret = walk_page_buffers(handle,
367                                         page_buffers(page),
368                                         from, to, NULL,
369                                         ocfs2_journal_dirty_data);
370                 if (ret < 0) 
371                         mlog_errno(ret);
372         }
373 out:
374         if (ret) {
375                 if (handle)
376                         ocfs2_commit_trans(osb, handle);
377                 handle = ERR_PTR(ret);
378         }
379         return handle;
380 }
381
382 static sector_t ocfs2_bmap(struct address_space *mapping, sector_t block)
383 {
384         sector_t status;
385         u64 p_blkno = 0;
386         int err = 0;
387         struct inode *inode = mapping->host;
388
389         mlog_entry("(block = %llu)\n", (unsigned long long)block);
390
391         /* We don't need to lock journal system files, since they aren't
392          * accessed concurrently from multiple nodes.
393          */
394         if (!INODE_JOURNAL(inode)) {
395                 err = ocfs2_meta_lock(inode, NULL, 0);
396                 if (err) {
397                         if (err != -ENOENT)
398                                 mlog_errno(err);
399                         goto bail;
400                 }
401                 down_read(&OCFS2_I(inode)->ip_alloc_sem);
402         }
403
404         err = ocfs2_extent_map_get_blocks(inode, block, &p_blkno, NULL, NULL);
405
406         if (!INODE_JOURNAL(inode)) {
407                 up_read(&OCFS2_I(inode)->ip_alloc_sem);
408                 ocfs2_meta_unlock(inode, 0);
409         }
410
411         if (err) {
412                 mlog(ML_ERROR, "get_blocks() failed, block = %llu\n",
413                      (unsigned long long)block);
414                 mlog_errno(err);
415                 goto bail;
416         }
417
418
419 bail:
420         status = err ? 0 : p_blkno;
421
422         mlog_exit((int)status);
423
424         return status;
425 }
426
427 /*
428  * TODO: Make this into a generic get_blocks function.
429  *
430  * From do_direct_io in direct-io.c:
431  *  "So what we do is to permit the ->get_blocks function to populate
432  *   bh.b_size with the size of IO which is permitted at this offset and
433  *   this i_blkbits."
434  *
435  * This function is called directly from get_more_blocks in direct-io.c.
436  *
437  * called like this: dio->get_blocks(dio->inode, fs_startblk,
438  *                                      fs_count, map_bh, dio->rw == WRITE);
439  */
440 static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock,
441                                      struct buffer_head *bh_result, int create)
442 {
443         int ret;
444         u64 p_blkno, inode_blocks, contig_blocks;
445         unsigned int ext_flags;
446         unsigned char blocksize_bits = inode->i_sb->s_blocksize_bits;
447         unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
448
449         /* This function won't even be called if the request isn't all
450          * nicely aligned and of the right size, so there's no need
451          * for us to check any of that. */
452
453         inode_blocks = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));
454
455         /*
456          * Any write past EOF is not allowed because we'd be extending.
457          */
458         if (create && (iblock + max_blocks) > inode_blocks) {
459                 ret = -EIO;
460                 goto bail;
461         }
462
463         /* This figures out the size of the next contiguous block, and
464          * our logical offset */
465         ret = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno,
466                                           &contig_blocks, &ext_flags);
467         if (ret) {
468                 mlog(ML_ERROR, "get_blocks() failed iblock=%llu\n",
469                      (unsigned long long)iblock);
470                 ret = -EIO;
471                 goto bail;
472         }
473
474         if (!ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)) && !p_blkno) {
475                 ocfs2_error(inode->i_sb,
476                             "Inode %llu has a hole at block %llu\n",
477                             (unsigned long long)OCFS2_I(inode)->ip_blkno,
478                             (unsigned long long)iblock);
479                 ret = -EROFS;
480                 goto bail;
481         }
482
483         /*
484          * get_more_blocks() expects us to describe a hole by clearing
485          * the mapped bit on bh_result().
486          *
487          * Consider an unwritten extent as a hole.
488          */
489         if (p_blkno && !(ext_flags & OCFS2_EXT_UNWRITTEN))
490                 map_bh(bh_result, inode->i_sb, p_blkno);
491         else {
492                 /*
493                  * ocfs2_prepare_inode_for_write() should have caught
494                  * the case where we'd be filling a hole and triggered
495                  * a buffered write instead.
496                  */
497                 if (create) {
498                         ret = -EIO;
499                         mlog_errno(ret);
500                         goto bail;
501                 }
502
503                 clear_buffer_mapped(bh_result);
504         }
505
506         /* make sure we don't map more than max_blocks blocks here as
507            that's all the kernel will handle at this point. */
508         if (max_blocks < contig_blocks)
509                 contig_blocks = max_blocks;
510         bh_result->b_size = contig_blocks << blocksize_bits;
511 bail:
512         return ret;
513 }
514
515 /* 
516  * ocfs2_dio_end_io is called by the dio core when a dio is finished.  We're
517  * particularly interested in the aio/dio case.  Like the core uses
518  * i_alloc_sem, we use the rw_lock DLM lock to protect io on one node from
519  * truncation on another.
520  */
521 static void ocfs2_dio_end_io(struct kiocb *iocb,
522                              loff_t offset,
523                              ssize_t bytes,
524                              void *private)
525 {
526         struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
527         int level;
528
529         /* this io's submitter should not have unlocked this before we could */
530         BUG_ON(!ocfs2_iocb_is_rw_locked(iocb));
531
532         ocfs2_iocb_clear_rw_locked(iocb);
533
534         level = ocfs2_iocb_rw_locked_level(iocb);
535         if (!level)
536                 up_read(&inode->i_alloc_sem);
537         ocfs2_rw_unlock(inode, level);
538 }
539
540 /*
541  * ocfs2_invalidatepage() and ocfs2_releasepage() are shamelessly stolen
542  * from ext3.  PageChecked() bits have been removed as OCFS2 does not
543  * do journalled data.
544  */
545 static void ocfs2_invalidatepage(struct page *page, unsigned long offset)
546 {
547         journal_t *journal = OCFS2_SB(page->mapping->host->i_sb)->journal->j_journal;
548
549         journal_invalidatepage(journal, page, offset);
550 }
551
552 static int ocfs2_releasepage(struct page *page, gfp_t wait)
553 {
554         journal_t *journal = OCFS2_SB(page->mapping->host->i_sb)->journal->j_journal;
555
556         if (!page_has_buffers(page))
557                 return 0;
558         return journal_try_to_free_buffers(journal, page, wait);
559 }
560
561 static ssize_t ocfs2_direct_IO(int rw,
562                                struct kiocb *iocb,
563                                const struct iovec *iov,
564                                loff_t offset,
565                                unsigned long nr_segs)
566 {
567         struct file *file = iocb->ki_filp;
568         struct inode *inode = file->f_path.dentry->d_inode->i_mapping->host;
569         int ret;
570
571         mlog_entry_void();
572
573         if (!ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb))) {
574                 /*
575                  * We get PR data locks even for O_DIRECT.  This
576                  * allows concurrent O_DIRECT I/O but doesn't let
577                  * O_DIRECT with extending and buffered zeroing writes
578                  * race.  If they did race then the buffered zeroing
579                  * could be written back after the O_DIRECT I/O.  It's
580                  * one thing to tell people not to mix buffered and
581                  * O_DIRECT writes, but expecting them to understand
582                  * that file extension is also an implicit buffered
583                  * write is too much.  By getting the PR we force
584                  * writeback of the buffered zeroing before
585                  * proceeding.
586                  */
587                 ret = ocfs2_data_lock(inode, 0);
588                 if (ret < 0) {
589                         mlog_errno(ret);
590                         goto out;
591                 }
592                 ocfs2_data_unlock(inode, 0);
593         }
594
595         ret = blockdev_direct_IO_no_locking(rw, iocb, inode,
596                                             inode->i_sb->s_bdev, iov, offset,
597                                             nr_segs, 
598                                             ocfs2_direct_IO_get_blocks,
599                                             ocfs2_dio_end_io);
600 out:
601         mlog_exit(ret);
602         return ret;
603 }
604
605 static void ocfs2_figure_cluster_boundaries(struct ocfs2_super *osb,
606                                             u32 cpos,
607                                             unsigned int *start,
608                                             unsigned int *end)
609 {
610         unsigned int cluster_start = 0, cluster_end = PAGE_CACHE_SIZE;
611
612         if (unlikely(PAGE_CACHE_SHIFT > osb->s_clustersize_bits)) {
613                 unsigned int cpp;
614
615                 cpp = 1 << (PAGE_CACHE_SHIFT - osb->s_clustersize_bits);
616
617                 cluster_start = cpos % cpp;
618                 cluster_start = cluster_start << osb->s_clustersize_bits;
619
620                 cluster_end = cluster_start + osb->s_clustersize;
621         }
622
623         BUG_ON(cluster_start > PAGE_SIZE);
624         BUG_ON(cluster_end > PAGE_SIZE);
625
626         if (start)
627                 *start = cluster_start;
628         if (end)
629                 *end = cluster_end;
630 }
631
632 /*
633  * 'from' and 'to' are the region in the page to avoid zeroing.
634  *
635  * If pagesize > clustersize, this function will avoid zeroing outside
636  * of the cluster boundary.
637  *
638  * from == to == 0 is code for "zero the entire cluster region"
639  */
640 static void ocfs2_clear_page_regions(struct page *page,
641                                      struct ocfs2_super *osb, u32 cpos,
642                                      unsigned from, unsigned to)
643 {
644         void *kaddr;
645         unsigned int cluster_start, cluster_end;
646
647         ocfs2_figure_cluster_boundaries(osb, cpos, &cluster_start, &cluster_end);
648
649         kaddr = kmap_atomic(page, KM_USER0);
650
651         if (from || to) {
652                 if (from > cluster_start)
653                         memset(kaddr + cluster_start, 0, from - cluster_start);
654                 if (to < cluster_end)
655                         memset(kaddr + to, 0, cluster_end - to);
656         } else {
657                 memset(kaddr + cluster_start, 0, cluster_end - cluster_start);
658         }
659
660         kunmap_atomic(kaddr, KM_USER0);
661 }
662
663 /*
664  * Some of this taken from block_prepare_write(). We already have our
665  * mapping by now though, and the entire write will be allocating or
666  * it won't, so not much need to use BH_New.
667  *
668  * This will also skip zeroing, which is handled externally.
669  */
670 int ocfs2_map_page_blocks(struct page *page, u64 *p_blkno,
671                           struct inode *inode, unsigned int from,
672                           unsigned int to, int new)
673 {
674         int ret = 0;
675         struct buffer_head *head, *bh, *wait[2], **wait_bh = wait;
676         unsigned int block_end, block_start;
677         unsigned int bsize = 1 << inode->i_blkbits;
678
679         if (!page_has_buffers(page))
680                 create_empty_buffers(page, bsize, 0);
681
682         head = page_buffers(page);
683         for (bh = head, block_start = 0; bh != head || !block_start;
684              bh = bh->b_this_page, block_start += bsize) {
685                 block_end = block_start + bsize;
686
687                 clear_buffer_new(bh);
688
689                 /*
690                  * Ignore blocks outside of our i/o range -
691                  * they may belong to unallocated clusters.
692                  */
693                 if (block_start >= to || block_end <= from) {
694                         if (PageUptodate(page))
695                                 set_buffer_uptodate(bh);
696                         continue;
697                 }
698
699                 /*
700                  * For an allocating write with cluster size >= page
701                  * size, we always write the entire page.
702                  */
703                 if (new)
704                         set_buffer_new(bh);
705
706                 if (!buffer_mapped(bh)) {
707                         map_bh(bh, inode->i_sb, *p_blkno);
708                         unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
709                 }
710
711                 if (PageUptodate(page)) {
712                         if (!buffer_uptodate(bh))
713                                 set_buffer_uptodate(bh);
714                 } else if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
715                            !buffer_new(bh) &&
716                            (block_start < from || block_end > to)) {
717                         ll_rw_block(READ, 1, &bh);
718                         *wait_bh++=bh;
719                 }
720
721                 *p_blkno = *p_blkno + 1;
722         }
723
724         /*
725          * If we issued read requests - let them complete.
726          */
727         while(wait_bh > wait) {
728                 wait_on_buffer(*--wait_bh);
729                 if (!buffer_uptodate(*wait_bh))
730                         ret = -EIO;
731         }
732
733         if (ret == 0 || !new)
734                 return ret;
735
736         /*
737          * If we get -EIO above, zero out any newly allocated blocks
738          * to avoid exposing stale data.
739          */
740         bh = head;
741         block_start = 0;
742         do {
743                 block_end = block_start + bsize;
744                 if (block_end <= from)
745                         goto next_bh;
746                 if (block_start >= to)
747                         break;
748
749                 zero_user_page(page, block_start, bh->b_size, KM_USER0);
750                 set_buffer_uptodate(bh);
751                 mark_buffer_dirty(bh);
752
753 next_bh:
754                 block_start = block_end;
755                 bh = bh->b_this_page;
756         } while (bh != head);
757
758         return ret;
759 }
760
761 #if (PAGE_CACHE_SIZE >= OCFS2_MAX_CLUSTERSIZE)
762 #define OCFS2_MAX_CTXT_PAGES    1
763 #else
764 #define OCFS2_MAX_CTXT_PAGES    (OCFS2_MAX_CLUSTERSIZE / PAGE_CACHE_SIZE)
765 #endif
766
767 #define OCFS2_MAX_CLUSTERS_PER_PAGE     (PAGE_CACHE_SIZE / OCFS2_MIN_CLUSTERSIZE)
768
769 /*
770  * Describe the state of a single cluster to be written to.
771  */
772 struct ocfs2_write_cluster_desc {
773         u32             c_cpos;
774         u32             c_phys;
775         /*
776          * Give this a unique field because c_phys eventually gets
777          * filled.
778          */
779         unsigned        c_new;
780         unsigned        c_unwritten;
781 };
782
783 static inline int ocfs2_should_zero_cluster(struct ocfs2_write_cluster_desc *d)
784 {
785         return d->c_new || d->c_unwritten;
786 }
787
788 struct ocfs2_write_ctxt {
789         /* Logical cluster position / len of write */
790         u32                             w_cpos;
791         u32                             w_clen;
792
793         struct ocfs2_write_cluster_desc w_desc[OCFS2_MAX_CLUSTERS_PER_PAGE];
794
795         /*
796          * This is true if page_size > cluster_size.
797          *
798          * It triggers a set of special cases during write which might
799          * have to deal with allocating writes to partial pages.
800          */
801         unsigned int                    w_large_pages;
802
803         /*
804          * Pages involved in this write.
805          *
806          * w_target_page is the page being written to by the user.
807          *
808          * w_pages is an array of pages which always contains
809          * w_target_page, and in the case of an allocating write with
810          * page_size < cluster size, it will contain zero'd and mapped
811          * pages adjacent to w_target_page which need to be written
812          * out in so that future reads from that region will get
813          * zero's.
814          */
815         struct page                     *w_pages[OCFS2_MAX_CTXT_PAGES];
816         unsigned int                    w_num_pages;
817         struct page                     *w_target_page;
818
819         /*
820          * ocfs2_write_end() uses this to know what the real range to
821          * write in the target should be.
822          */
823         unsigned int                    w_target_from;
824         unsigned int                    w_target_to;
825
826         /*
827          * We could use journal_current_handle() but this is cleaner,
828          * IMHO -Mark
829          */
830         handle_t                        *w_handle;
831
832         struct buffer_head              *w_di_bh;
833
834         struct ocfs2_cached_dealloc_ctxt w_dealloc;
835 };
836
837 static void ocfs2_free_write_ctxt(struct ocfs2_write_ctxt *wc)
838 {
839         int i;
840
841         for(i = 0; i < wc->w_num_pages; i++) {
842                 if (wc->w_pages[i] == NULL)
843                         continue;
844
845                 unlock_page(wc->w_pages[i]);
846                 mark_page_accessed(wc->w_pages[i]);
847                 page_cache_release(wc->w_pages[i]);
848         }
849
850         brelse(wc->w_di_bh);
851         kfree(wc);
852 }
853
854 static int ocfs2_alloc_write_ctxt(struct ocfs2_write_ctxt **wcp,
855                                   struct ocfs2_super *osb, loff_t pos,
856                                   unsigned len, struct buffer_head *di_bh)
857 {
858         u32 cend;
859         struct ocfs2_write_ctxt *wc;
860
861         wc = kzalloc(sizeof(struct ocfs2_write_ctxt), GFP_NOFS);
862         if (!wc)
863                 return -ENOMEM;
864
865         wc->w_cpos = pos >> osb->s_clustersize_bits;
866         cend = (pos + len - 1) >> osb->s_clustersize_bits;
867         wc->w_clen = cend - wc->w_cpos + 1;
868         get_bh(di_bh);
869         wc->w_di_bh = di_bh;
870
871         if (unlikely(PAGE_CACHE_SHIFT > osb->s_clustersize_bits))
872                 wc->w_large_pages = 1;
873         else
874                 wc->w_large_pages = 0;
875
876         ocfs2_init_dealloc_ctxt(&wc->w_dealloc);
877
878         *wcp = wc;
879
880         return 0;
881 }
882
883 /*
884  * If a page has any new buffers, zero them out here, and mark them uptodate
885  * and dirty so they'll be written out (in order to prevent uninitialised
886  * block data from leaking). And clear the new bit.
887  */
888 static void ocfs2_zero_new_buffers(struct page *page, unsigned from, unsigned to)
889 {
890         unsigned int block_start, block_end;
891         struct buffer_head *head, *bh;
892
893         BUG_ON(!PageLocked(page));
894         if (!page_has_buffers(page))
895                 return;
896
897         bh = head = page_buffers(page);
898         block_start = 0;
899         do {
900                 block_end = block_start + bh->b_size;
901
902                 if (buffer_new(bh)) {
903                         if (block_end > from && block_start < to) {
904                                 if (!PageUptodate(page)) {
905                                         unsigned start, end;
906
907                                         start = max(from, block_start);
908                                         end = min(to, block_end);
909
910                                         zero_user_page(page, start, end - start, KM_USER0);
911                                         set_buffer_uptodate(bh);
912                                 }
913
914                                 clear_buffer_new(bh);
915                                 mark_buffer_dirty(bh);
916                         }
917                 }
918
919                 block_start = block_end;
920                 bh = bh->b_this_page;
921         } while (bh != head);
922 }
923
924 /*
925  * Only called when we have a failure during allocating write to write
926  * zero's to the newly allocated region.
927  */
928 static void ocfs2_write_failure(struct inode *inode,
929                                 struct ocfs2_write_ctxt *wc,
930                                 loff_t user_pos, unsigned user_len)
931 {
932         int i;
933         unsigned from, to;
934         struct page *tmppage;
935
936         ocfs2_zero_new_buffers(wc->w_target_page, user_pos, user_len);
937
938         if (wc->w_large_pages) {
939                 from = wc->w_target_from;
940                 to = wc->w_target_to;
941         } else {
942                 from = 0;
943                 to = PAGE_CACHE_SIZE;
944         }
945
946         for(i = 0; i < wc->w_num_pages; i++) {
947                 tmppage = wc->w_pages[i];
948
949                 if (ocfs2_should_order_data(inode))
950                         walk_page_buffers(wc->w_handle, page_buffers(tmppage),
951                                           from, to, NULL,
952                                           ocfs2_journal_dirty_data);
953
954                 block_commit_write(tmppage, from, to);
955         }
956 }
957
958 static int ocfs2_prepare_page_for_write(struct inode *inode, u64 *p_blkno,
959                                         struct ocfs2_write_ctxt *wc,
960                                         struct page *page, u32 cpos,
961                                         loff_t user_pos, unsigned user_len,
962                                         int new)
963 {
964         int ret;
965         unsigned int map_from = 0, map_to = 0;
966         unsigned int cluster_start, cluster_end;
967         unsigned int user_data_from = 0, user_data_to = 0;
968
969         ocfs2_figure_cluster_boundaries(OCFS2_SB(inode->i_sb), cpos,
970                                         &cluster_start, &cluster_end);
971
972         if (page == wc->w_target_page) {
973                 map_from = user_pos & (PAGE_CACHE_SIZE - 1);
974                 map_to = map_from + user_len;
975
976                 if (new)
977                         ret = ocfs2_map_page_blocks(page, p_blkno, inode,
978                                                     cluster_start, cluster_end,
979                                                     new);
980                 else
981                         ret = ocfs2_map_page_blocks(page, p_blkno, inode,
982                                                     map_from, map_to, new);
983                 if (ret) {
984                         mlog_errno(ret);
985                         goto out;
986                 }
987
988                 user_data_from = map_from;
989                 user_data_to = map_to;
990                 if (new) {
991                         map_from = cluster_start;
992                         map_to = cluster_end;
993                 }
994
995                 wc->w_target_from = map_from;
996                 wc->w_target_to = map_to;
997         } else {
998                 /*
999                  * If we haven't allocated the new page yet, we
1000                  * shouldn't be writing it out without copying user
1001                  * data. This is likely a math error from the caller.
1002                  */
1003                 BUG_ON(!new);
1004
1005                 map_from = cluster_start;
1006                 map_to = cluster_end;
1007
1008                 ret = ocfs2_map_page_blocks(page, p_blkno, inode,
1009                                             cluster_start, cluster_end, new);
1010                 if (ret) {
1011                         mlog_errno(ret);
1012                         goto out;
1013                 }
1014         }
1015
1016         /*
1017          * Parts of newly allocated pages need to be zero'd.
1018          *
1019          * Above, we have also rewritten 'to' and 'from' - as far as
1020          * the rest of the function is concerned, the entire cluster
1021          * range inside of a page needs to be written.
1022          *
1023          * We can skip this if the page is up to date - it's already
1024          * been zero'd from being read in as a hole.
1025          */
1026         if (new && !PageUptodate(page))
1027                 ocfs2_clear_page_regions(page, OCFS2_SB(inode->i_sb),
1028                                          cpos, user_data_from, user_data_to);
1029
1030         flush_dcache_page(page);
1031
1032 out:
1033         return ret;
1034 }
1035
1036 /*
1037  * This function will only grab one clusters worth of pages.
1038  */
1039 static int ocfs2_grab_pages_for_write(struct address_space *mapping,
1040                                       struct ocfs2_write_ctxt *wc,
1041                                       u32 cpos, loff_t user_pos, int new,
1042                                       struct page *mmap_page)
1043 {
1044         int ret = 0, i;
1045         unsigned long start, target_index, index;
1046         struct inode *inode = mapping->host;
1047
1048         target_index = user_pos >> PAGE_CACHE_SHIFT;
1049
1050         /*
1051          * Figure out how many pages we'll be manipulating here. For
1052          * non allocating write, we just change the one
1053          * page. Otherwise, we'll need a whole clusters worth.
1054          */
1055         if (new) {
1056                 wc->w_num_pages = ocfs2_pages_per_cluster(inode->i_sb);
1057                 start = ocfs2_align_clusters_to_page_index(inode->i_sb, cpos);
1058         } else {
1059                 wc->w_num_pages = 1;
1060                 start = target_index;
1061         }
1062
1063         for(i = 0; i < wc->w_num_pages; i++) {
1064                 index = start + i;
1065
1066                 if (index == target_index && mmap_page) {
1067                         /*
1068                          * ocfs2_pagemkwrite() is a little different
1069                          * and wants us to directly use the page
1070                          * passed in.
1071                          */
1072                         lock_page(mmap_page);
1073
1074                         if (mmap_page->mapping != mapping) {
1075                                 unlock_page(mmap_page);
1076                                 /*
1077                                  * Sanity check - the locking in
1078                                  * ocfs2_pagemkwrite() should ensure
1079                                  * that this code doesn't trigger.
1080                                  */
1081                                 ret = -EINVAL;
1082                                 mlog_errno(ret);
1083                                 goto out;
1084                         }
1085
1086                         page_cache_get(mmap_page);
1087                         wc->w_pages[i] = mmap_page;
1088                 } else {
1089                         wc->w_pages[i] = find_or_create_page(mapping, index,
1090                                                              GFP_NOFS);
1091                         if (!wc->w_pages[i]) {
1092                                 ret = -ENOMEM;
1093                                 mlog_errno(ret);
1094                                 goto out;
1095                         }
1096                 }
1097
1098                 if (index == target_index)
1099                         wc->w_target_page = wc->w_pages[i];
1100         }
1101 out:
1102         return ret;
1103 }
1104
1105 /*
1106  * Prepare a single cluster for write one cluster into the file.
1107  */
1108 static int ocfs2_write_cluster(struct address_space *mapping,
1109                                u32 phys, unsigned int unwritten,
1110                                struct ocfs2_alloc_context *data_ac,
1111                                struct ocfs2_alloc_context *meta_ac,
1112                                struct ocfs2_write_ctxt *wc, u32 cpos,
1113                                loff_t user_pos, unsigned user_len)
1114 {
1115         int ret, i, new, should_zero = 0;
1116         u64 v_blkno, p_blkno;
1117         struct inode *inode = mapping->host;
1118
1119         new = phys == 0 ? 1 : 0;
1120         if (new || unwritten)
1121                 should_zero = 1;
1122
1123         if (new) {
1124                 u32 tmp_pos;
1125
1126                 /*
1127                  * This is safe to call with the page locks - it won't take
1128                  * any additional semaphores or cluster locks.
1129                  */
1130                 tmp_pos = cpos;
1131                 ret = ocfs2_do_extend_allocation(OCFS2_SB(inode->i_sb), inode,
1132                                                  &tmp_pos, 1, 0, wc->w_di_bh,
1133                                                  wc->w_handle, data_ac,
1134                                                  meta_ac, NULL);
1135                 /*
1136                  * This shouldn't happen because we must have already
1137                  * calculated the correct meta data allocation required. The
1138                  * internal tree allocation code should know how to increase
1139                  * transaction credits itself.
1140                  *
1141                  * If need be, we could handle -EAGAIN for a
1142                  * RESTART_TRANS here.
1143                  */
1144                 mlog_bug_on_msg(ret == -EAGAIN,
1145                                 "Inode %llu: EAGAIN return during allocation.\n",
1146                                 (unsigned long long)OCFS2_I(inode)->ip_blkno);
1147                 if (ret < 0) {
1148                         mlog_errno(ret);
1149                         goto out;
1150                 }
1151         } else if (unwritten) {
1152                 ret = ocfs2_mark_extent_written(inode, wc->w_di_bh,
1153                                                 wc->w_handle, cpos, 1, phys,
1154                                                 meta_ac, &wc->w_dealloc);
1155                 if (ret < 0) {
1156                         mlog_errno(ret);
1157                         goto out;
1158                 }
1159         }
1160
1161         if (should_zero)
1162                 v_blkno = ocfs2_clusters_to_blocks(inode->i_sb, cpos);
1163         else
1164                 v_blkno = user_pos >> inode->i_sb->s_blocksize_bits;
1165
1166         /*
1167          * The only reason this should fail is due to an inability to
1168          * find the extent added.
1169          */
1170         ret = ocfs2_extent_map_get_blocks(inode, v_blkno, &p_blkno, NULL,
1171                                           NULL);
1172         if (ret < 0) {
1173                 ocfs2_error(inode->i_sb, "Corrupting extend for inode %llu, "
1174                             "at logical block %llu",
1175                             (unsigned long long)OCFS2_I(inode)->ip_blkno,
1176                             (unsigned long long)v_blkno);
1177                 goto out;
1178         }
1179
1180         BUG_ON(p_blkno == 0);
1181
1182         for(i = 0; i < wc->w_num_pages; i++) {
1183                 int tmpret;
1184
1185                 tmpret = ocfs2_prepare_page_for_write(inode, &p_blkno, wc,
1186                                                       wc->w_pages[i], cpos,
1187                                                       user_pos, user_len,
1188                                                       should_zero);
1189                 if (tmpret) {
1190                         mlog_errno(tmpret);
1191                         if (ret == 0)
1192                                 tmpret = ret;
1193                 }
1194         }
1195
1196         /*
1197          * We only have cleanup to do in case of allocating write.
1198          */
1199         if (ret && new)
1200                 ocfs2_write_failure(inode, wc, user_pos, user_len);
1201
1202 out:
1203
1204         return ret;
1205 }
1206
1207 static int ocfs2_write_cluster_by_desc(struct address_space *mapping,
1208                                        struct ocfs2_alloc_context *data_ac,
1209                                        struct ocfs2_alloc_context *meta_ac,
1210                                        struct ocfs2_write_ctxt *wc,
1211                                        loff_t pos, unsigned len)
1212 {
1213         int ret, i;
1214         struct ocfs2_write_cluster_desc *desc;
1215
1216         for (i = 0; i < wc->w_clen; i++) {
1217                 desc = &wc->w_desc[i];
1218
1219                 ret = ocfs2_write_cluster(mapping, desc->c_phys,
1220                                           desc->c_unwritten, data_ac, meta_ac,
1221                                           wc, desc->c_cpos, pos, len);
1222                 if (ret) {
1223                         mlog_errno(ret);
1224                         goto out;
1225                 }
1226         }
1227
1228         ret = 0;
1229 out:
1230         return ret;
1231 }
1232
1233 /*
1234  * ocfs2_write_end() wants to know which parts of the target page it
1235  * should complete the write on. It's easiest to compute them ahead of
1236  * time when a more complete view of the write is available.
1237  */
1238 static void ocfs2_set_target_boundaries(struct ocfs2_super *osb,
1239                                         struct ocfs2_write_ctxt *wc,
1240                                         loff_t pos, unsigned len, int alloc)
1241 {
1242         struct ocfs2_write_cluster_desc *desc;
1243
1244         wc->w_target_from = pos & (PAGE_CACHE_SIZE - 1);
1245         wc->w_target_to = wc->w_target_from + len;
1246
1247         if (alloc == 0)
1248                 return;
1249
1250         /*
1251          * Allocating write - we may have different boundaries based
1252          * on page size and cluster size.
1253          *
1254          * NOTE: We can no longer compute one value from the other as
1255          * the actual write length and user provided length may be
1256          * different.
1257          */
1258
1259         if (wc->w_large_pages) {
1260                 /*
1261                  * We only care about the 1st and last cluster within
1262                  * our range and whether they should be zero'd or not. Either
1263                  * value may be extended out to the start/end of a
1264                  * newly allocated cluster.
1265                  */
1266                 desc = &wc->w_desc[0];
1267                 if (ocfs2_should_zero_cluster(desc))
1268                         ocfs2_figure_cluster_boundaries(osb,
1269                                                         desc->c_cpos,
1270                                                         &wc->w_target_from,
1271                                                         NULL);
1272
1273                 desc = &wc->w_desc[wc->w_clen - 1];
1274                 if (ocfs2_should_zero_cluster(desc))
1275                         ocfs2_figure_cluster_boundaries(osb,
1276                                                         desc->c_cpos,
1277                                                         NULL,
1278                                                         &wc->w_target_to);
1279         } else {
1280                 wc->w_target_from = 0;
1281                 wc->w_target_to = PAGE_CACHE_SIZE;
1282         }
1283 }
1284
1285 /*
1286  * Populate each single-cluster write descriptor in the write context
1287  * with information about the i/o to be done.
1288  *
1289  * Returns the number of clusters that will have to be allocated, as
1290  * well as a worst case estimate of the number of extent records that
1291  * would have to be created during a write to an unwritten region.
1292  */
1293 static int ocfs2_populate_write_desc(struct inode *inode,
1294                                      struct ocfs2_write_ctxt *wc,
1295                                      unsigned int *clusters_to_alloc,
1296                                      unsigned int *extents_to_split)
1297 {
1298         int ret;
1299         struct ocfs2_write_cluster_desc *desc;
1300         unsigned int num_clusters = 0;
1301         unsigned int ext_flags = 0;
1302         u32 phys = 0;
1303         int i;
1304
1305         *clusters_to_alloc = 0;
1306         *extents_to_split = 0;
1307
1308         for (i = 0; i < wc->w_clen; i++) {
1309                 desc = &wc->w_desc[i];
1310                 desc->c_cpos = wc->w_cpos + i;
1311
1312                 if (num_clusters == 0) {
1313                         /*
1314                          * Need to look up the next extent record.
1315                          */
1316                         ret = ocfs2_get_clusters(inode, desc->c_cpos, &phys,
1317                                                  &num_clusters, &ext_flags);
1318                         if (ret) {
1319                                 mlog_errno(ret);
1320                                 goto out;
1321                         }
1322
1323                         /*
1324                          * Assume worst case - that we're writing in
1325                          * the middle of the extent.
1326                          *
1327                          * We can assume that the write proceeds from
1328                          * left to right, in which case the extent
1329                          * insert code is smart enough to coalesce the
1330                          * next splits into the previous records created.
1331                          */
1332                         if (ext_flags & OCFS2_EXT_UNWRITTEN)
1333                                 *extents_to_split = *extents_to_split + 2;
1334                 } else if (phys) {
1335                         /*
1336                          * Only increment phys if it doesn't describe
1337                          * a hole.
1338                          */
1339                         phys++;
1340                 }
1341
1342                 desc->c_phys = phys;
1343                 if (phys == 0) {
1344                         desc->c_new = 1;
1345                         *clusters_to_alloc = *clusters_to_alloc + 1;
1346                 }
1347                 if (ext_flags & OCFS2_EXT_UNWRITTEN)
1348                         desc->c_unwritten = 1;
1349
1350                 num_clusters--;
1351         }
1352
1353         ret = 0;
1354 out:
1355         return ret;
1356 }
1357
1358 int ocfs2_write_begin_nolock(struct address_space *mapping,
1359                              loff_t pos, unsigned len, unsigned flags,
1360                              struct page **pagep, void **fsdata,
1361                              struct buffer_head *di_bh, struct page *mmap_page)
1362 {
1363         int ret, credits = OCFS2_INODE_UPDATE_CREDITS;
1364         unsigned int clusters_to_alloc, extents_to_split;
1365         struct ocfs2_write_ctxt *wc;
1366         struct inode *inode = mapping->host;
1367         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
1368         struct ocfs2_dinode *di;
1369         struct ocfs2_alloc_context *data_ac = NULL;
1370         struct ocfs2_alloc_context *meta_ac = NULL;
1371         handle_t *handle;
1372
1373         ret = ocfs2_alloc_write_ctxt(&wc, osb, pos, len, di_bh);
1374         if (ret) {
1375                 mlog_errno(ret);
1376                 return ret;
1377         }
1378
1379         ret = ocfs2_populate_write_desc(inode, wc, &clusters_to_alloc,
1380                                         &extents_to_split);
1381         if (ret) {
1382                 mlog_errno(ret);
1383                 goto out;
1384         }
1385
1386         di = (struct ocfs2_dinode *)wc->w_di_bh->b_data;
1387
1388         /*
1389          * We set w_target_from, w_target_to here so that
1390          * ocfs2_write_end() knows which range in the target page to
1391          * write out. An allocation requires that we write the entire
1392          * cluster range.
1393          */
1394         if (clusters_to_alloc || extents_to_split) {
1395                 /*
1396                  * XXX: We are stretching the limits of
1397                  * ocfs2_lock_allocators(). It greatly over-estimates
1398                  * the work to be done.
1399                  */
1400                 ret = ocfs2_lock_allocators(inode, di, clusters_to_alloc,
1401                                             extents_to_split, &data_ac, &meta_ac);
1402                 if (ret) {
1403                         mlog_errno(ret);
1404                         goto out;
1405                 }
1406
1407                 credits = ocfs2_calc_extend_credits(inode->i_sb, di,
1408                                                     clusters_to_alloc);
1409
1410         }
1411
1412         ocfs2_set_target_boundaries(osb, wc, pos, len,
1413                                     clusters_to_alloc + extents_to_split);
1414
1415         handle = ocfs2_start_trans(osb, credits);
1416         if (IS_ERR(handle)) {
1417                 ret = PTR_ERR(handle);
1418                 mlog_errno(ret);
1419                 goto out;
1420         }
1421
1422         wc->w_handle = handle;
1423
1424         /*
1425          * We don't want this to fail in ocfs2_write_end(), so do it
1426          * here.
1427          */
1428         ret = ocfs2_journal_access(handle, inode, wc->w_di_bh,
1429                                    OCFS2_JOURNAL_ACCESS_WRITE);
1430         if (ret) {
1431                 mlog_errno(ret);
1432                 goto out_commit;
1433         }
1434
1435         /*
1436          * Fill our page array first. That way we've grabbed enough so
1437          * that we can zero and flush if we error after adding the
1438          * extent.
1439          */
1440         ret = ocfs2_grab_pages_for_write(mapping, wc, wc->w_cpos, pos,
1441                                          clusters_to_alloc + extents_to_split,
1442                                          mmap_page);
1443         if (ret) {
1444                 mlog_errno(ret);
1445                 goto out_commit;
1446         }
1447
1448         ret = ocfs2_write_cluster_by_desc(mapping, data_ac, meta_ac, wc, pos,
1449                                           len);
1450         if (ret) {
1451                 mlog_errno(ret);
1452                 goto out_commit;
1453         }
1454
1455         if (data_ac)
1456                 ocfs2_free_alloc_context(data_ac);
1457         if (meta_ac)
1458                 ocfs2_free_alloc_context(meta_ac);
1459
1460         *pagep = wc->w_target_page;
1461         *fsdata = wc;
1462         return 0;
1463 out_commit:
1464         ocfs2_commit_trans(osb, handle);
1465
1466 out:
1467         ocfs2_free_write_ctxt(wc);
1468
1469         if (data_ac)
1470                 ocfs2_free_alloc_context(data_ac);
1471         if (meta_ac)
1472                 ocfs2_free_alloc_context(meta_ac);
1473         return ret;
1474 }
1475
1476 int ocfs2_write_begin(struct file *file, struct address_space *mapping,
1477                       loff_t pos, unsigned len, unsigned flags,
1478                       struct page **pagep, void **fsdata)
1479 {
1480         int ret;
1481         struct buffer_head *di_bh = NULL;
1482         struct inode *inode = mapping->host;
1483
1484         ret = ocfs2_meta_lock(inode, &di_bh, 1);
1485         if (ret) {
1486                 mlog_errno(ret);
1487                 return ret;
1488         }
1489
1490         /*
1491          * Take alloc sem here to prevent concurrent lookups. That way
1492          * the mapping, zeroing and tree manipulation within
1493          * ocfs2_write() will be safe against ->readpage(). This
1494          * should also serve to lock out allocation from a shared
1495          * writeable region.
1496          */
1497         down_write(&OCFS2_I(inode)->ip_alloc_sem);
1498
1499         ret = ocfs2_data_lock(inode, 1);
1500         if (ret) {
1501                 mlog_errno(ret);
1502                 goto out_fail;
1503         }
1504
1505         ret = ocfs2_write_begin_nolock(mapping, pos, len, flags, pagep,
1506                                        fsdata, di_bh, NULL);
1507         if (ret) {
1508                 mlog_errno(ret);
1509                 goto out_fail_data;
1510         }
1511
1512         brelse(di_bh);
1513
1514         return 0;
1515
1516 out_fail_data:
1517         ocfs2_data_unlock(inode, 1);
1518 out_fail:
1519         up_write(&OCFS2_I(inode)->ip_alloc_sem);
1520
1521         brelse(di_bh);
1522         ocfs2_meta_unlock(inode, 1);
1523
1524         return ret;
1525 }
1526
1527 int ocfs2_write_end_nolock(struct address_space *mapping,
1528                            loff_t pos, unsigned len, unsigned copied,
1529                            struct page *page, void *fsdata)
1530 {
1531         int i;
1532         unsigned from, to, start = pos & (PAGE_CACHE_SIZE - 1);
1533         struct inode *inode = mapping->host;
1534         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
1535         struct ocfs2_write_ctxt *wc = fsdata;
1536         struct ocfs2_dinode *di = (struct ocfs2_dinode *)wc->w_di_bh->b_data;
1537         handle_t *handle = wc->w_handle;
1538         struct page *tmppage;
1539
1540         if (unlikely(copied < len)) {
1541                 if (!PageUptodate(wc->w_target_page))
1542                         copied = 0;
1543
1544                 ocfs2_zero_new_buffers(wc->w_target_page, start+copied,
1545                                        start+len);
1546         }
1547         flush_dcache_page(wc->w_target_page);
1548
1549         for(i = 0; i < wc->w_num_pages; i++) {
1550                 tmppage = wc->w_pages[i];
1551
1552                 if (tmppage == wc->w_target_page) {
1553                         from = wc->w_target_from;
1554                         to = wc->w_target_to;
1555
1556                         BUG_ON(from > PAGE_CACHE_SIZE ||
1557                                to > PAGE_CACHE_SIZE ||
1558                                to < from);
1559                 } else {
1560                         /*
1561                          * Pages adjacent to the target (if any) imply
1562                          * a hole-filling write in which case we want
1563                          * to flush their entire range.
1564                          */
1565                         from = 0;
1566                         to = PAGE_CACHE_SIZE;
1567                 }
1568
1569                 if (ocfs2_should_order_data(inode))
1570                         walk_page_buffers(wc->w_handle, page_buffers(tmppage),
1571                                           from, to, NULL,
1572                                           ocfs2_journal_dirty_data);
1573
1574                 block_commit_write(tmppage, from, to);
1575         }
1576
1577         pos += copied;
1578         if (pos > inode->i_size) {
1579                 i_size_write(inode, pos);
1580                 mark_inode_dirty(inode);
1581         }
1582         inode->i_blocks = ocfs2_inode_sector_count(inode);
1583         di->i_size = cpu_to_le64((u64)i_size_read(inode));
1584         inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1585         di->i_mtime = di->i_ctime = cpu_to_le64(inode->i_mtime.tv_sec);
1586         di->i_mtime_nsec = di->i_ctime_nsec = cpu_to_le32(inode->i_mtime.tv_nsec);
1587         ocfs2_journal_dirty(handle, wc->w_di_bh);
1588
1589         ocfs2_commit_trans(osb, handle);
1590
1591         ocfs2_run_deallocs(osb, &wc->w_dealloc);
1592
1593         ocfs2_free_write_ctxt(wc);
1594
1595         return copied;
1596 }
1597
1598 int ocfs2_write_end(struct file *file, struct address_space *mapping,
1599                     loff_t pos, unsigned len, unsigned copied,
1600                     struct page *page, void *fsdata)
1601 {
1602         int ret;
1603         struct inode *inode = mapping->host;
1604
1605         ret = ocfs2_write_end_nolock(mapping, pos, len, copied, page, fsdata);
1606
1607         ocfs2_data_unlock(inode, 1);
1608         up_write(&OCFS2_I(inode)->ip_alloc_sem);
1609         ocfs2_meta_unlock(inode, 1);
1610
1611         return ret;
1612 }
1613
1614 const struct address_space_operations ocfs2_aops = {
1615         .readpage       = ocfs2_readpage,
1616         .writepage      = ocfs2_writepage,
1617         .bmap           = ocfs2_bmap,
1618         .sync_page      = block_sync_page,
1619         .direct_IO      = ocfs2_direct_IO,
1620         .invalidatepage = ocfs2_invalidatepage,
1621         .releasepage    = ocfs2_releasepage,
1622         .migratepage    = buffer_migrate_page,
1623 };