ac97bca282d25ebb5943c41ac05fef385d93abf1
[sfrench/cifs-2.6.git] / 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 #include <linux/mpage.h>
30 #include <linux/quotaops.h>
31
32 #include <cluster/masklog.h>
33
34 #include "ocfs2.h"
35
36 #include "alloc.h"
37 #include "aops.h"
38 #include "dlmglue.h"
39 #include "extent_map.h"
40 #include "file.h"
41 #include "inode.h"
42 #include "journal.h"
43 #include "suballoc.h"
44 #include "super.h"
45 #include "symlink.h"
46 #include "refcounttree.h"
47 #include "ocfs2_trace.h"
48
49 #include "buffer_head_io.h"
50
51 static int ocfs2_symlink_get_block(struct inode *inode, sector_t iblock,
52                                    struct buffer_head *bh_result, int create)
53 {
54         int err = -EIO;
55         int status;
56         struct ocfs2_dinode *fe = NULL;
57         struct buffer_head *bh = NULL;
58         struct buffer_head *buffer_cache_bh = NULL;
59         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
60         void *kaddr;
61
62         trace_ocfs2_symlink_get_block(
63                         (unsigned long long)OCFS2_I(inode)->ip_blkno,
64                         (unsigned long long)iblock, bh_result, create);
65
66         BUG_ON(ocfs2_inode_is_fast_symlink(inode));
67
68         if ((iblock << inode->i_sb->s_blocksize_bits) > PATH_MAX + 1) {
69                 mlog(ML_ERROR, "block offset > PATH_MAX: %llu",
70                      (unsigned long long)iblock);
71                 goto bail;
72         }
73
74         status = ocfs2_read_inode_block(inode, &bh);
75         if (status < 0) {
76                 mlog_errno(status);
77                 goto bail;
78         }
79         fe = (struct ocfs2_dinode *) bh->b_data;
80
81         if ((u64)iblock >= ocfs2_clusters_to_blocks(inode->i_sb,
82                                                     le32_to_cpu(fe->i_clusters))) {
83                 mlog(ML_ERROR, "block offset is outside the allocated size: "
84                      "%llu\n", (unsigned long long)iblock);
85                 goto bail;
86         }
87
88         /* We don't use the page cache to create symlink data, so if
89          * need be, copy it over from the buffer cache. */
90         if (!buffer_uptodate(bh_result) && ocfs2_inode_is_new(inode)) {
91                 u64 blkno = le64_to_cpu(fe->id2.i_list.l_recs[0].e_blkno) +
92                             iblock;
93                 buffer_cache_bh = sb_getblk(osb->sb, blkno);
94                 if (!buffer_cache_bh) {
95                         mlog(ML_ERROR, "couldn't getblock for symlink!\n");
96                         goto bail;
97                 }
98
99                 /* we haven't locked out transactions, so a commit
100                  * could've happened. Since we've got a reference on
101                  * the bh, even if it commits while we're doing the
102                  * copy, the data is still good. */
103                 if (buffer_jbd(buffer_cache_bh)
104                     && ocfs2_inode_is_new(inode)) {
105                         kaddr = kmap_atomic(bh_result->b_page, KM_USER0);
106                         if (!kaddr) {
107                                 mlog(ML_ERROR, "couldn't kmap!\n");
108                                 goto bail;
109                         }
110                         memcpy(kaddr + (bh_result->b_size * iblock),
111                                buffer_cache_bh->b_data,
112                                bh_result->b_size);
113                         kunmap_atomic(kaddr, KM_USER0);
114                         set_buffer_uptodate(bh_result);
115                 }
116                 brelse(buffer_cache_bh);
117         }
118
119         map_bh(bh_result, inode->i_sb,
120                le64_to_cpu(fe->id2.i_list.l_recs[0].e_blkno) + iblock);
121
122         err = 0;
123
124 bail:
125         brelse(bh);
126
127         return err;
128 }
129
130 int ocfs2_get_block(struct inode *inode, sector_t iblock,
131                     struct buffer_head *bh_result, int create)
132 {
133         int err = 0;
134         unsigned int ext_flags;
135         u64 max_blocks = bh_result->b_size >> inode->i_blkbits;
136         u64 p_blkno, count, past_eof;
137         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
138
139         trace_ocfs2_get_block((unsigned long long)OCFS2_I(inode)->ip_blkno,
140                               (unsigned long long)iblock, bh_result, create);
141
142         if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_SYSTEM_FILE)
143                 mlog(ML_NOTICE, "get_block on system inode 0x%p (%lu)\n",
144                      inode, inode->i_ino);
145
146         if (S_ISLNK(inode->i_mode)) {
147                 /* this always does I/O for some reason. */
148                 err = ocfs2_symlink_get_block(inode, iblock, bh_result, create);
149                 goto bail;
150         }
151
152         err = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno, &count,
153                                           &ext_flags);
154         if (err) {
155                 mlog(ML_ERROR, "Error %d from get_blocks(0x%p, %llu, 1, "
156                      "%llu, NULL)\n", err, inode, (unsigned long long)iblock,
157                      (unsigned long long)p_blkno);
158                 goto bail;
159         }
160
161         if (max_blocks < count)
162                 count = max_blocks;
163
164         /*
165          * ocfs2 never allocates in this function - the only time we
166          * need to use BH_New is when we're extending i_size on a file
167          * system which doesn't support holes, in which case BH_New
168          * allows __block_write_begin() to zero.
169          *
170          * If we see this on a sparse file system, then a truncate has
171          * raced us and removed the cluster. In this case, we clear
172          * the buffers dirty and uptodate bits and let the buffer code
173          * ignore it as a hole.
174          */
175         if (create && p_blkno == 0 && ocfs2_sparse_alloc(osb)) {
176                 clear_buffer_dirty(bh_result);
177                 clear_buffer_uptodate(bh_result);
178                 goto bail;
179         }
180
181         /* Treat the unwritten extent as a hole for zeroing purposes. */
182         if (p_blkno && !(ext_flags & OCFS2_EXT_UNWRITTEN))
183                 map_bh(bh_result, inode->i_sb, p_blkno);
184
185         bh_result->b_size = count << inode->i_blkbits;
186
187         if (!ocfs2_sparse_alloc(osb)) {
188                 if (p_blkno == 0) {
189                         err = -EIO;
190                         mlog(ML_ERROR,
191                              "iblock = %llu p_blkno = %llu blkno=(%llu)\n",
192                              (unsigned long long)iblock,
193                              (unsigned long long)p_blkno,
194                              (unsigned long long)OCFS2_I(inode)->ip_blkno);
195                         mlog(ML_ERROR, "Size %llu, clusters %u\n", (unsigned long long)i_size_read(inode), OCFS2_I(inode)->ip_clusters);
196                         dump_stack();
197                         goto bail;
198                 }
199         }
200
201         past_eof = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));
202
203         trace_ocfs2_get_block_end((unsigned long long)OCFS2_I(inode)->ip_blkno,
204                                   (unsigned long long)past_eof);
205         if (create && (iblock >= past_eof))
206                 set_buffer_new(bh_result);
207
208 bail:
209         if (err < 0)
210                 err = -EIO;
211
212         return err;
213 }
214
215 int ocfs2_read_inline_data(struct inode *inode, struct page *page,
216                            struct buffer_head *di_bh)
217 {
218         void *kaddr;
219         loff_t size;
220         struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
221
222         if (!(le16_to_cpu(di->i_dyn_features) & OCFS2_INLINE_DATA_FL)) {
223                 ocfs2_error(inode->i_sb, "Inode %llu lost inline data flag",
224                             (unsigned long long)OCFS2_I(inode)->ip_blkno);
225                 return -EROFS;
226         }
227
228         size = i_size_read(inode);
229
230         if (size > PAGE_CACHE_SIZE ||
231             size > ocfs2_max_inline_data_with_xattr(inode->i_sb, di)) {
232                 ocfs2_error(inode->i_sb,
233                             "Inode %llu has with inline data has bad size: %Lu",
234                             (unsigned long long)OCFS2_I(inode)->ip_blkno,
235                             (unsigned long long)size);
236                 return -EROFS;
237         }
238
239         kaddr = kmap_atomic(page, KM_USER0);
240         if (size)
241                 memcpy(kaddr, di->id2.i_data.id_data, size);
242         /* Clear the remaining part of the page */
243         memset(kaddr + size, 0, PAGE_CACHE_SIZE - size);
244         flush_dcache_page(page);
245         kunmap_atomic(kaddr, KM_USER0);
246
247         SetPageUptodate(page);
248
249         return 0;
250 }
251
252 static int ocfs2_readpage_inline(struct inode *inode, struct page *page)
253 {
254         int ret;
255         struct buffer_head *di_bh = NULL;
256
257         BUG_ON(!PageLocked(page));
258         BUG_ON(!(OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL));
259
260         ret = ocfs2_read_inode_block(inode, &di_bh);
261         if (ret) {
262                 mlog_errno(ret);
263                 goto out;
264         }
265
266         ret = ocfs2_read_inline_data(inode, page, di_bh);
267 out:
268         unlock_page(page);
269
270         brelse(di_bh);
271         return ret;
272 }
273
274 static int ocfs2_readpage(struct file *file, struct page *page)
275 {
276         struct inode *inode = page->mapping->host;
277         struct ocfs2_inode_info *oi = OCFS2_I(inode);
278         loff_t start = (loff_t)page->index << PAGE_CACHE_SHIFT;
279         int ret, unlock = 1;
280
281         trace_ocfs2_readpage((unsigned long long)oi->ip_blkno,
282                              (page ? page->index : 0));
283
284         ret = ocfs2_inode_lock_with_page(inode, NULL, 0, page);
285         if (ret != 0) {
286                 if (ret == AOP_TRUNCATED_PAGE)
287                         unlock = 0;
288                 mlog_errno(ret);
289                 goto out;
290         }
291
292         if (down_read_trylock(&oi->ip_alloc_sem) == 0) {
293                 ret = AOP_TRUNCATED_PAGE;
294                 goto out_inode_unlock;
295         }
296
297         /*
298          * i_size might have just been updated as we grabed the meta lock.  We
299          * might now be discovering a truncate that hit on another node.
300          * block_read_full_page->get_block freaks out if it is asked to read
301          * beyond the end of a file, so we check here.  Callers
302          * (generic_file_read, vm_ops->fault) are clever enough to check i_size
303          * and notice that the page they just read isn't needed.
304          *
305          * XXX sys_readahead() seems to get that wrong?
306          */
307         if (start >= i_size_read(inode)) {
308                 zero_user(page, 0, PAGE_SIZE);
309                 SetPageUptodate(page);
310                 ret = 0;
311                 goto out_alloc;
312         }
313
314         if (oi->ip_dyn_features & OCFS2_INLINE_DATA_FL)
315                 ret = ocfs2_readpage_inline(inode, page);
316         else
317                 ret = block_read_full_page(page, ocfs2_get_block);
318         unlock = 0;
319
320 out_alloc:
321         up_read(&OCFS2_I(inode)->ip_alloc_sem);
322 out_inode_unlock:
323         ocfs2_inode_unlock(inode, 0);
324 out:
325         if (unlock)
326                 unlock_page(page);
327         return ret;
328 }
329
330 /*
331  * This is used only for read-ahead. Failures or difficult to handle
332  * situations are safe to ignore.
333  *
334  * Right now, we don't bother with BH_Boundary - in-inode extent lists
335  * are quite large (243 extents on 4k blocks), so most inodes don't
336  * grow out to a tree. If need be, detecting boundary extents could
337  * trivially be added in a future version of ocfs2_get_block().
338  */
339 static int ocfs2_readpages(struct file *filp, struct address_space *mapping,
340                            struct list_head *pages, unsigned nr_pages)
341 {
342         int ret, err = -EIO;
343         struct inode *inode = mapping->host;
344         struct ocfs2_inode_info *oi = OCFS2_I(inode);
345         loff_t start;
346         struct page *last;
347
348         /*
349          * Use the nonblocking flag for the dlm code to avoid page
350          * lock inversion, but don't bother with retrying.
351          */
352         ret = ocfs2_inode_lock_full(inode, NULL, 0, OCFS2_LOCK_NONBLOCK);
353         if (ret)
354                 return err;
355
356         if (down_read_trylock(&oi->ip_alloc_sem) == 0) {
357                 ocfs2_inode_unlock(inode, 0);
358                 return err;
359         }
360
361         /*
362          * Don't bother with inline-data. There isn't anything
363          * to read-ahead in that case anyway...
364          */
365         if (oi->ip_dyn_features & OCFS2_INLINE_DATA_FL)
366                 goto out_unlock;
367
368         /*
369          * Check whether a remote node truncated this file - we just
370          * drop out in that case as it's not worth handling here.
371          */
372         last = list_entry(pages->prev, struct page, lru);
373         start = (loff_t)last->index << PAGE_CACHE_SHIFT;
374         if (start >= i_size_read(inode))
375                 goto out_unlock;
376
377         err = mpage_readpages(mapping, pages, nr_pages, ocfs2_get_block);
378
379 out_unlock:
380         up_read(&oi->ip_alloc_sem);
381         ocfs2_inode_unlock(inode, 0);
382
383         return err;
384 }
385
386 /* Note: Because we don't support holes, our allocation has
387  * already happened (allocation writes zeros to the file data)
388  * so we don't have to worry about ordered writes in
389  * ocfs2_writepage.
390  *
391  * ->writepage is called during the process of invalidating the page cache
392  * during blocked lock processing.  It can't block on any cluster locks
393  * to during block mapping.  It's relying on the fact that the block
394  * mapping can't have disappeared under the dirty pages that it is
395  * being asked to write back.
396  */
397 static int ocfs2_writepage(struct page *page, struct writeback_control *wbc)
398 {
399         trace_ocfs2_writepage(
400                 (unsigned long long)OCFS2_I(page->mapping->host)->ip_blkno,
401                 page->index);
402
403         return block_write_full_page(page, ocfs2_get_block, wbc);
404 }
405
406 /* Taken from ext3. We don't necessarily need the full blown
407  * functionality yet, but IMHO it's better to cut and paste the whole
408  * thing so we can avoid introducing our own bugs (and easily pick up
409  * their fixes when they happen) --Mark */
410 int walk_page_buffers(  handle_t *handle,
411                         struct buffer_head *head,
412                         unsigned from,
413                         unsigned to,
414                         int *partial,
415                         int (*fn)(      handle_t *handle,
416                                         struct buffer_head *bh))
417 {
418         struct buffer_head *bh;
419         unsigned block_start, block_end;
420         unsigned blocksize = head->b_size;
421         int err, ret = 0;
422         struct buffer_head *next;
423
424         for (   bh = head, block_start = 0;
425                 ret == 0 && (bh != head || !block_start);
426                 block_start = block_end, bh = next)
427         {
428                 next = bh->b_this_page;
429                 block_end = block_start + blocksize;
430                 if (block_end <= from || block_start >= to) {
431                         if (partial && !buffer_uptodate(bh))
432                                 *partial = 1;
433                         continue;
434                 }
435                 err = (*fn)(handle, bh);
436                 if (!ret)
437                         ret = err;
438         }
439         return ret;
440 }
441
442 static sector_t ocfs2_bmap(struct address_space *mapping, sector_t block)
443 {
444         sector_t status;
445         u64 p_blkno = 0;
446         int err = 0;
447         struct inode *inode = mapping->host;
448
449         trace_ocfs2_bmap((unsigned long long)OCFS2_I(inode)->ip_blkno,
450                          (unsigned long long)block);
451
452         /* We don't need to lock journal system files, since they aren't
453          * accessed concurrently from multiple nodes.
454          */
455         if (!INODE_JOURNAL(inode)) {
456                 err = ocfs2_inode_lock(inode, NULL, 0);
457                 if (err) {
458                         if (err != -ENOENT)
459                                 mlog_errno(err);
460                         goto bail;
461                 }
462                 down_read(&OCFS2_I(inode)->ip_alloc_sem);
463         }
464
465         if (!(OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL))
466                 err = ocfs2_extent_map_get_blocks(inode, block, &p_blkno, NULL,
467                                                   NULL);
468
469         if (!INODE_JOURNAL(inode)) {
470                 up_read(&OCFS2_I(inode)->ip_alloc_sem);
471                 ocfs2_inode_unlock(inode, 0);
472         }
473
474         if (err) {
475                 mlog(ML_ERROR, "get_blocks() failed, block = %llu\n",
476                      (unsigned long long)block);
477                 mlog_errno(err);
478                 goto bail;
479         }
480
481 bail:
482         status = err ? 0 : p_blkno;
483
484         return status;
485 }
486
487 /*
488  * TODO: Make this into a generic get_blocks function.
489  *
490  * From do_direct_io in direct-io.c:
491  *  "So what we do is to permit the ->get_blocks function to populate
492  *   bh.b_size with the size of IO which is permitted at this offset and
493  *   this i_blkbits."
494  *
495  * This function is called directly from get_more_blocks in direct-io.c.
496  *
497  * called like this: dio->get_blocks(dio->inode, fs_startblk,
498  *                                      fs_count, map_bh, dio->rw == WRITE);
499  *
500  * Note that we never bother to allocate blocks here, and thus ignore the
501  * create argument.
502  */
503 static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock,
504                                      struct buffer_head *bh_result, int create)
505 {
506         int ret;
507         u64 p_blkno, inode_blocks, contig_blocks;
508         unsigned int ext_flags;
509         unsigned char blocksize_bits = inode->i_sb->s_blocksize_bits;
510         unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
511
512         /* This function won't even be called if the request isn't all
513          * nicely aligned and of the right size, so there's no need
514          * for us to check any of that. */
515
516         inode_blocks = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));
517
518         /* This figures out the size of the next contiguous block, and
519          * our logical offset */
520         ret = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno,
521                                           &contig_blocks, &ext_flags);
522         if (ret) {
523                 mlog(ML_ERROR, "get_blocks() failed iblock=%llu\n",
524                      (unsigned long long)iblock);
525                 ret = -EIO;
526                 goto bail;
527         }
528
529         /* We should already CoW the refcounted extent in case of create. */
530         BUG_ON(create && (ext_flags & OCFS2_EXT_REFCOUNTED));
531
532         /*
533          * get_more_blocks() expects us to describe a hole by clearing
534          * the mapped bit on bh_result().
535          *
536          * Consider an unwritten extent as a hole.
537          */
538         if (p_blkno && !(ext_flags & OCFS2_EXT_UNWRITTEN))
539                 map_bh(bh_result, inode->i_sb, p_blkno);
540         else
541                 clear_buffer_mapped(bh_result);
542
543         /* make sure we don't map more than max_blocks blocks here as
544            that's all the kernel will handle at this point. */
545         if (max_blocks < contig_blocks)
546                 contig_blocks = max_blocks;
547         bh_result->b_size = contig_blocks << blocksize_bits;
548 bail:
549         return ret;
550 }
551
552 /*
553  * ocfs2_dio_end_io is called by the dio core when a dio is finished.  We're
554  * particularly interested in the aio/dio case.  Like the core uses
555  * i_alloc_sem, we use the rw_lock DLM lock to protect io on one node from
556  * truncation on another.
557  */
558 static void ocfs2_dio_end_io(struct kiocb *iocb,
559                              loff_t offset,
560                              ssize_t bytes,
561                              void *private,
562                              int ret,
563                              bool is_async)
564 {
565         struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
566         int level;
567
568         /* this io's submitter should not have unlocked this before we could */
569         BUG_ON(!ocfs2_iocb_is_rw_locked(iocb));
570
571         if (ocfs2_iocb_is_sem_locked(iocb)) {
572                 up_read(&inode->i_alloc_sem);
573                 ocfs2_iocb_clear_sem_locked(iocb);
574         }
575
576         ocfs2_iocb_clear_rw_locked(iocb);
577
578         level = ocfs2_iocb_rw_locked_level(iocb);
579         ocfs2_rw_unlock(inode, level);
580
581         if (is_async)
582                 aio_complete(iocb, ret, 0);
583 }
584
585 /*
586  * ocfs2_invalidatepage() and ocfs2_releasepage() are shamelessly stolen
587  * from ext3.  PageChecked() bits have been removed as OCFS2 does not
588  * do journalled data.
589  */
590 static void ocfs2_invalidatepage(struct page *page, unsigned long offset)
591 {
592         journal_t *journal = OCFS2_SB(page->mapping->host->i_sb)->journal->j_journal;
593
594         jbd2_journal_invalidatepage(journal, page, offset);
595 }
596
597 static int ocfs2_releasepage(struct page *page, gfp_t wait)
598 {
599         journal_t *journal = OCFS2_SB(page->mapping->host->i_sb)->journal->j_journal;
600
601         if (!page_has_buffers(page))
602                 return 0;
603         return jbd2_journal_try_to_free_buffers(journal, page, wait);
604 }
605
606 static ssize_t ocfs2_direct_IO(int rw,
607                                struct kiocb *iocb,
608                                const struct iovec *iov,
609                                loff_t offset,
610                                unsigned long nr_segs)
611 {
612         struct file *file = iocb->ki_filp;
613         struct inode *inode = file->f_path.dentry->d_inode->i_mapping->host;
614
615         /*
616          * Fallback to buffered I/O if we see an inode without
617          * extents.
618          */
619         if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL)
620                 return 0;
621
622         /* Fallback to buffered I/O if we are appending. */
623         if (i_size_read(inode) <= offset)
624                 return 0;
625
626         return __blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev,
627                                     iov, offset, nr_segs,
628                                     ocfs2_direct_IO_get_blocks,
629                                     ocfs2_dio_end_io, NULL, 0);
630 }
631
632 static void ocfs2_figure_cluster_boundaries(struct ocfs2_super *osb,
633                                             u32 cpos,
634                                             unsigned int *start,
635                                             unsigned int *end)
636 {
637         unsigned int cluster_start = 0, cluster_end = PAGE_CACHE_SIZE;
638
639         if (unlikely(PAGE_CACHE_SHIFT > osb->s_clustersize_bits)) {
640                 unsigned int cpp;
641
642                 cpp = 1 << (PAGE_CACHE_SHIFT - osb->s_clustersize_bits);
643
644                 cluster_start = cpos % cpp;
645                 cluster_start = cluster_start << osb->s_clustersize_bits;
646
647                 cluster_end = cluster_start + osb->s_clustersize;
648         }
649
650         BUG_ON(cluster_start > PAGE_SIZE);
651         BUG_ON(cluster_end > PAGE_SIZE);
652
653         if (start)
654                 *start = cluster_start;
655         if (end)
656                 *end = cluster_end;
657 }
658
659 /*
660  * 'from' and 'to' are the region in the page to avoid zeroing.
661  *
662  * If pagesize > clustersize, this function will avoid zeroing outside
663  * of the cluster boundary.
664  *
665  * from == to == 0 is code for "zero the entire cluster region"
666  */
667 static void ocfs2_clear_page_regions(struct page *page,
668                                      struct ocfs2_super *osb, u32 cpos,
669                                      unsigned from, unsigned to)
670 {
671         void *kaddr;
672         unsigned int cluster_start, cluster_end;
673
674         ocfs2_figure_cluster_boundaries(osb, cpos, &cluster_start, &cluster_end);
675
676         kaddr = kmap_atomic(page, KM_USER0);
677
678         if (from || to) {
679                 if (from > cluster_start)
680                         memset(kaddr + cluster_start, 0, from - cluster_start);
681                 if (to < cluster_end)
682                         memset(kaddr + to, 0, cluster_end - to);
683         } else {
684                 memset(kaddr + cluster_start, 0, cluster_end - cluster_start);
685         }
686
687         kunmap_atomic(kaddr, KM_USER0);
688 }
689
690 /*
691  * Nonsparse file systems fully allocate before we get to the write
692  * code. This prevents ocfs2_write() from tagging the write as an
693  * allocating one, which means ocfs2_map_page_blocks() might try to
694  * read-in the blocks at the tail of our file. Avoid reading them by
695  * testing i_size against each block offset.
696  */
697 static int ocfs2_should_read_blk(struct inode *inode, struct page *page,
698                                  unsigned int block_start)
699 {
700         u64 offset = page_offset(page) + block_start;
701
702         if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)))
703                 return 1;
704
705         if (i_size_read(inode) > offset)
706                 return 1;
707
708         return 0;
709 }
710
711 /*
712  * Some of this taken from __block_write_begin(). We already have our
713  * mapping by now though, and the entire write will be allocating or
714  * it won't, so not much need to use BH_New.
715  *
716  * This will also skip zeroing, which is handled externally.
717  */
718 int ocfs2_map_page_blocks(struct page *page, u64 *p_blkno,
719                           struct inode *inode, unsigned int from,
720                           unsigned int to, int new)
721 {
722         int ret = 0;
723         struct buffer_head *head, *bh, *wait[2], **wait_bh = wait;
724         unsigned int block_end, block_start;
725         unsigned int bsize = 1 << inode->i_blkbits;
726
727         if (!page_has_buffers(page))
728                 create_empty_buffers(page, bsize, 0);
729
730         head = page_buffers(page);
731         for (bh = head, block_start = 0; bh != head || !block_start;
732              bh = bh->b_this_page, block_start += bsize) {
733                 block_end = block_start + bsize;
734
735                 clear_buffer_new(bh);
736
737                 /*
738                  * Ignore blocks outside of our i/o range -
739                  * they may belong to unallocated clusters.
740                  */
741                 if (block_start >= to || block_end <= from) {
742                         if (PageUptodate(page))
743                                 set_buffer_uptodate(bh);
744                         continue;
745                 }
746
747                 /*
748                  * For an allocating write with cluster size >= page
749                  * size, we always write the entire page.
750                  */
751                 if (new)
752                         set_buffer_new(bh);
753
754                 if (!buffer_mapped(bh)) {
755                         map_bh(bh, inode->i_sb, *p_blkno);
756                         unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
757                 }
758
759                 if (PageUptodate(page)) {
760                         if (!buffer_uptodate(bh))
761                                 set_buffer_uptodate(bh);
762                 } else if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
763                            !buffer_new(bh) &&
764                            ocfs2_should_read_blk(inode, page, block_start) &&
765                            (block_start < from || block_end > to)) {
766                         ll_rw_block(READ, 1, &bh);
767                         *wait_bh++=bh;
768                 }
769
770                 *p_blkno = *p_blkno + 1;
771         }
772
773         /*
774          * If we issued read requests - let them complete.
775          */
776         while(wait_bh > wait) {
777                 wait_on_buffer(*--wait_bh);
778                 if (!buffer_uptodate(*wait_bh))
779                         ret = -EIO;
780         }
781
782         if (ret == 0 || !new)
783                 return ret;
784
785         /*
786          * If we get -EIO above, zero out any newly allocated blocks
787          * to avoid exposing stale data.
788          */
789         bh = head;
790         block_start = 0;
791         do {
792                 block_end = block_start + bsize;
793                 if (block_end <= from)
794                         goto next_bh;
795                 if (block_start >= to)
796                         break;
797
798                 zero_user(page, block_start, bh->b_size);
799                 set_buffer_uptodate(bh);
800                 mark_buffer_dirty(bh);
801
802 next_bh:
803                 block_start = block_end;
804                 bh = bh->b_this_page;
805         } while (bh != head);
806
807         return ret;
808 }
809
810 #if (PAGE_CACHE_SIZE >= OCFS2_MAX_CLUSTERSIZE)
811 #define OCFS2_MAX_CTXT_PAGES    1
812 #else
813 #define OCFS2_MAX_CTXT_PAGES    (OCFS2_MAX_CLUSTERSIZE / PAGE_CACHE_SIZE)
814 #endif
815
816 #define OCFS2_MAX_CLUSTERS_PER_PAGE     (PAGE_CACHE_SIZE / OCFS2_MIN_CLUSTERSIZE)
817
818 /*
819  * Describe the state of a single cluster to be written to.
820  */
821 struct ocfs2_write_cluster_desc {
822         u32             c_cpos;
823         u32             c_phys;
824         /*
825          * Give this a unique field because c_phys eventually gets
826          * filled.
827          */
828         unsigned        c_new;
829         unsigned        c_unwritten;
830         unsigned        c_needs_zero;
831 };
832
833 struct ocfs2_write_ctxt {
834         /* Logical cluster position / len of write */
835         u32                             w_cpos;
836         u32                             w_clen;
837
838         /* First cluster allocated in a nonsparse extend */
839         u32                             w_first_new_cpos;
840
841         struct ocfs2_write_cluster_desc w_desc[OCFS2_MAX_CLUSTERS_PER_PAGE];
842
843         /*
844          * This is true if page_size > cluster_size.
845          *
846          * It triggers a set of special cases during write which might
847          * have to deal with allocating writes to partial pages.
848          */
849         unsigned int                    w_large_pages;
850
851         /*
852          * Pages involved in this write.
853          *
854          * w_target_page is the page being written to by the user.
855          *
856          * w_pages is an array of pages which always contains
857          * w_target_page, and in the case of an allocating write with
858          * page_size < cluster size, it will contain zero'd and mapped
859          * pages adjacent to w_target_page which need to be written
860          * out in so that future reads from that region will get
861          * zero's.
862          */
863         unsigned int                    w_num_pages;
864         struct page                     *w_pages[OCFS2_MAX_CTXT_PAGES];
865         struct page                     *w_target_page;
866
867         /*
868          * ocfs2_write_end() uses this to know what the real range to
869          * write in the target should be.
870          */
871         unsigned int                    w_target_from;
872         unsigned int                    w_target_to;
873
874         /*
875          * We could use journal_current_handle() but this is cleaner,
876          * IMHO -Mark
877          */
878         handle_t                        *w_handle;
879
880         struct buffer_head              *w_di_bh;
881
882         struct ocfs2_cached_dealloc_ctxt w_dealloc;
883 };
884
885 void ocfs2_unlock_and_free_pages(struct page **pages, int num_pages)
886 {
887         int i;
888
889         for(i = 0; i < num_pages; i++) {
890                 if (pages[i]) {
891                         unlock_page(pages[i]);
892                         mark_page_accessed(pages[i]);
893                         page_cache_release(pages[i]);
894                 }
895         }
896 }
897
898 static void ocfs2_free_write_ctxt(struct ocfs2_write_ctxt *wc)
899 {
900         ocfs2_unlock_and_free_pages(wc->w_pages, wc->w_num_pages);
901
902         brelse(wc->w_di_bh);
903         kfree(wc);
904 }
905
906 static int ocfs2_alloc_write_ctxt(struct ocfs2_write_ctxt **wcp,
907                                   struct ocfs2_super *osb, loff_t pos,
908                                   unsigned len, struct buffer_head *di_bh)
909 {
910         u32 cend;
911         struct ocfs2_write_ctxt *wc;
912
913         wc = kzalloc(sizeof(struct ocfs2_write_ctxt), GFP_NOFS);
914         if (!wc)
915                 return -ENOMEM;
916
917         wc->w_cpos = pos >> osb->s_clustersize_bits;
918         wc->w_first_new_cpos = UINT_MAX;
919         cend = (pos + len - 1) >> osb->s_clustersize_bits;
920         wc->w_clen = cend - wc->w_cpos + 1;
921         get_bh(di_bh);
922         wc->w_di_bh = di_bh;
923
924         if (unlikely(PAGE_CACHE_SHIFT > osb->s_clustersize_bits))
925                 wc->w_large_pages = 1;
926         else
927                 wc->w_large_pages = 0;
928
929         ocfs2_init_dealloc_ctxt(&wc->w_dealloc);
930
931         *wcp = wc;
932
933         return 0;
934 }
935
936 /*
937  * If a page has any new buffers, zero them out here, and mark them uptodate
938  * and dirty so they'll be written out (in order to prevent uninitialised
939  * block data from leaking). And clear the new bit.
940  */
941 static void ocfs2_zero_new_buffers(struct page *page, unsigned from, unsigned to)
942 {
943         unsigned int block_start, block_end;
944         struct buffer_head *head, *bh;
945
946         BUG_ON(!PageLocked(page));
947         if (!page_has_buffers(page))
948                 return;
949
950         bh = head = page_buffers(page);
951         block_start = 0;
952         do {
953                 block_end = block_start + bh->b_size;
954
955                 if (buffer_new(bh)) {
956                         if (block_end > from && block_start < to) {
957                                 if (!PageUptodate(page)) {
958                                         unsigned start, end;
959
960                                         start = max(from, block_start);
961                                         end = min(to, block_end);
962
963                                         zero_user_segment(page, start, end);
964                                         set_buffer_uptodate(bh);
965                                 }
966
967                                 clear_buffer_new(bh);
968                                 mark_buffer_dirty(bh);
969                         }
970                 }
971
972                 block_start = block_end;
973                 bh = bh->b_this_page;
974         } while (bh != head);
975 }
976
977 /*
978  * Only called when we have a failure during allocating write to write
979  * zero's to the newly allocated region.
980  */
981 static void ocfs2_write_failure(struct inode *inode,
982                                 struct ocfs2_write_ctxt *wc,
983                                 loff_t user_pos, unsigned user_len)
984 {
985         int i;
986         unsigned from = user_pos & (PAGE_CACHE_SIZE - 1),
987                 to = user_pos + user_len;
988         struct page *tmppage;
989
990         ocfs2_zero_new_buffers(wc->w_target_page, from, to);
991
992         for(i = 0; i < wc->w_num_pages; i++) {
993                 tmppage = wc->w_pages[i];
994
995                 if (page_has_buffers(tmppage)) {
996                         if (ocfs2_should_order_data(inode))
997                                 ocfs2_jbd2_file_inode(wc->w_handle, inode);
998
999                         block_commit_write(tmppage, from, to);
1000                 }
1001         }
1002 }
1003
1004 static int ocfs2_prepare_page_for_write(struct inode *inode, u64 *p_blkno,
1005                                         struct ocfs2_write_ctxt *wc,
1006                                         struct page *page, u32 cpos,
1007                                         loff_t user_pos, unsigned user_len,
1008                                         int new)
1009 {
1010         int ret;
1011         unsigned int map_from = 0, map_to = 0;
1012         unsigned int cluster_start, cluster_end;
1013         unsigned int user_data_from = 0, user_data_to = 0;
1014
1015         ocfs2_figure_cluster_boundaries(OCFS2_SB(inode->i_sb), cpos,
1016                                         &cluster_start, &cluster_end);
1017
1018         /* treat the write as new if the a hole/lseek spanned across
1019          * the page boundary.
1020          */
1021         new = new | ((i_size_read(inode) <= page_offset(page)) &&
1022                         (page_offset(page) <= user_pos));
1023
1024         if (page == wc->w_target_page) {
1025                 map_from = user_pos & (PAGE_CACHE_SIZE - 1);
1026                 map_to = map_from + user_len;
1027
1028                 if (new)
1029                         ret = ocfs2_map_page_blocks(page, p_blkno, inode,
1030                                                     cluster_start, cluster_end,
1031                                                     new);
1032                 else
1033                         ret = ocfs2_map_page_blocks(page, p_blkno, inode,
1034                                                     map_from, map_to, new);
1035                 if (ret) {
1036                         mlog_errno(ret);
1037                         goto out;
1038                 }
1039
1040                 user_data_from = map_from;
1041                 user_data_to = map_to;
1042                 if (new) {
1043                         map_from = cluster_start;
1044                         map_to = cluster_end;
1045                 }
1046         } else {
1047                 /*
1048                  * If we haven't allocated the new page yet, we
1049                  * shouldn't be writing it out without copying user
1050                  * data. This is likely a math error from the caller.
1051                  */
1052                 BUG_ON(!new);
1053
1054                 map_from = cluster_start;
1055                 map_to = cluster_end;
1056
1057                 ret = ocfs2_map_page_blocks(page, p_blkno, inode,
1058                                             cluster_start, cluster_end, new);
1059                 if (ret) {
1060                         mlog_errno(ret);
1061                         goto out;
1062                 }
1063         }
1064
1065         /*
1066          * Parts of newly allocated pages need to be zero'd.
1067          *
1068          * Above, we have also rewritten 'to' and 'from' - as far as
1069          * the rest of the function is concerned, the entire cluster
1070          * range inside of a page needs to be written.
1071          *
1072          * We can skip this if the page is up to date - it's already
1073          * been zero'd from being read in as a hole.
1074          */
1075         if (new && !PageUptodate(page))
1076                 ocfs2_clear_page_regions(page, OCFS2_SB(inode->i_sb),
1077                                          cpos, user_data_from, user_data_to);
1078
1079         flush_dcache_page(page);
1080
1081 out:
1082         return ret;
1083 }
1084
1085 /*
1086  * This function will only grab one clusters worth of pages.
1087  */
1088 static int ocfs2_grab_pages_for_write(struct address_space *mapping,
1089                                       struct ocfs2_write_ctxt *wc,
1090                                       u32 cpos, loff_t user_pos,
1091                                       unsigned user_len, int new,
1092                                       struct page *mmap_page)
1093 {
1094         int ret = 0, i;
1095         unsigned long start, target_index, end_index, index;
1096         struct inode *inode = mapping->host;
1097         loff_t last_byte;
1098
1099         target_index = user_pos >> PAGE_CACHE_SHIFT;
1100
1101         /*
1102          * Figure out how many pages we'll be manipulating here. For
1103          * non allocating write, we just change the one
1104          * page. Otherwise, we'll need a whole clusters worth.  If we're
1105          * writing past i_size, we only need enough pages to cover the
1106          * last page of the write.
1107          */
1108         if (new) {
1109                 wc->w_num_pages = ocfs2_pages_per_cluster(inode->i_sb);
1110                 start = ocfs2_align_clusters_to_page_index(inode->i_sb, cpos);
1111                 /*
1112                  * We need the index *past* the last page we could possibly
1113                  * touch.  This is the page past the end of the write or
1114                  * i_size, whichever is greater.
1115                  */
1116                 last_byte = max(user_pos + user_len, i_size_read(inode));
1117                 BUG_ON(last_byte < 1);
1118                 end_index = ((last_byte - 1) >> PAGE_CACHE_SHIFT) + 1;
1119                 if ((start + wc->w_num_pages) > end_index)
1120                         wc->w_num_pages = end_index - start;
1121         } else {
1122                 wc->w_num_pages = 1;
1123                 start = target_index;
1124         }
1125
1126         for(i = 0; i < wc->w_num_pages; i++) {
1127                 index = start + i;
1128
1129                 if (index == target_index && mmap_page) {
1130                         /*
1131                          * ocfs2_pagemkwrite() is a little different
1132                          * and wants us to directly use the page
1133                          * passed in.
1134                          */
1135                         lock_page(mmap_page);
1136
1137                         if (mmap_page->mapping != mapping) {
1138                                 unlock_page(mmap_page);
1139                                 /*
1140                                  * Sanity check - the locking in
1141                                  * ocfs2_pagemkwrite() should ensure
1142                                  * that this code doesn't trigger.
1143                                  */
1144                                 ret = -EINVAL;
1145                                 mlog_errno(ret);
1146                                 goto out;
1147                         }
1148
1149                         page_cache_get(mmap_page);
1150                         wc->w_pages[i] = mmap_page;
1151                 } else {
1152                         wc->w_pages[i] = find_or_create_page(mapping, index,
1153                                                              GFP_NOFS);
1154                         if (!wc->w_pages[i]) {
1155                                 ret = -ENOMEM;
1156                                 mlog_errno(ret);
1157                                 goto out;
1158                         }
1159                 }
1160
1161                 if (index == target_index)
1162                         wc->w_target_page = wc->w_pages[i];
1163         }
1164 out:
1165         return ret;
1166 }
1167
1168 /*
1169  * Prepare a single cluster for write one cluster into the file.
1170  */
1171 static int ocfs2_write_cluster(struct address_space *mapping,
1172                                u32 phys, unsigned int unwritten,
1173                                unsigned int should_zero,
1174                                struct ocfs2_alloc_context *data_ac,
1175                                struct ocfs2_alloc_context *meta_ac,
1176                                struct ocfs2_write_ctxt *wc, u32 cpos,
1177                                loff_t user_pos, unsigned user_len)
1178 {
1179         int ret, i, new;
1180         u64 v_blkno, p_blkno;
1181         struct inode *inode = mapping->host;
1182         struct ocfs2_extent_tree et;
1183
1184         new = phys == 0 ? 1 : 0;
1185         if (new) {
1186                 u32 tmp_pos;
1187
1188                 /*
1189                  * This is safe to call with the page locks - it won't take
1190                  * any additional semaphores or cluster locks.
1191                  */
1192                 tmp_pos = cpos;
1193                 ret = ocfs2_add_inode_data(OCFS2_SB(inode->i_sb), inode,
1194                                            &tmp_pos, 1, 0, wc->w_di_bh,
1195                                            wc->w_handle, data_ac,
1196                                            meta_ac, NULL);
1197                 /*
1198                  * This shouldn't happen because we must have already
1199                  * calculated the correct meta data allocation required. The
1200                  * internal tree allocation code should know how to increase
1201                  * transaction credits itself.
1202                  *
1203                  * If need be, we could handle -EAGAIN for a
1204                  * RESTART_TRANS here.
1205                  */
1206                 mlog_bug_on_msg(ret == -EAGAIN,
1207                                 "Inode %llu: EAGAIN return during allocation.\n",
1208                                 (unsigned long long)OCFS2_I(inode)->ip_blkno);
1209                 if (ret < 0) {
1210                         mlog_errno(ret);
1211                         goto out;
1212                 }
1213         } else if (unwritten) {
1214                 ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode),
1215                                               wc->w_di_bh);
1216                 ret = ocfs2_mark_extent_written(inode, &et,
1217                                                 wc->w_handle, cpos, 1, phys,
1218                                                 meta_ac, &wc->w_dealloc);
1219                 if (ret < 0) {
1220                         mlog_errno(ret);
1221                         goto out;
1222                 }
1223         }
1224
1225         if (should_zero)
1226                 v_blkno = ocfs2_clusters_to_blocks(inode->i_sb, cpos);
1227         else
1228                 v_blkno = user_pos >> inode->i_sb->s_blocksize_bits;
1229
1230         /*
1231          * The only reason this should fail is due to an inability to
1232          * find the extent added.
1233          */
1234         ret = ocfs2_extent_map_get_blocks(inode, v_blkno, &p_blkno, NULL,
1235                                           NULL);
1236         if (ret < 0) {
1237                 ocfs2_error(inode->i_sb, "Corrupting extend for inode %llu, "
1238                             "at logical block %llu",
1239                             (unsigned long long)OCFS2_I(inode)->ip_blkno,
1240                             (unsigned long long)v_blkno);
1241                 goto out;
1242         }
1243
1244         BUG_ON(p_blkno == 0);
1245
1246         for(i = 0; i < wc->w_num_pages; i++) {
1247                 int tmpret;
1248
1249                 tmpret = ocfs2_prepare_page_for_write(inode, &p_blkno, wc,
1250                                                       wc->w_pages[i], cpos,
1251                                                       user_pos, user_len,
1252                                                       should_zero);
1253                 if (tmpret) {
1254                         mlog_errno(tmpret);
1255                         if (ret == 0)
1256                                 ret = tmpret;
1257                 }
1258         }
1259
1260         /*
1261          * We only have cleanup to do in case of allocating write.
1262          */
1263         if (ret && new)
1264                 ocfs2_write_failure(inode, wc, user_pos, user_len);
1265
1266 out:
1267
1268         return ret;
1269 }
1270
1271 static int ocfs2_write_cluster_by_desc(struct address_space *mapping,
1272                                        struct ocfs2_alloc_context *data_ac,
1273                                        struct ocfs2_alloc_context *meta_ac,
1274                                        struct ocfs2_write_ctxt *wc,
1275                                        loff_t pos, unsigned len)
1276 {
1277         int ret, i;
1278         loff_t cluster_off;
1279         unsigned int local_len = len;
1280         struct ocfs2_write_cluster_desc *desc;
1281         struct ocfs2_super *osb = OCFS2_SB(mapping->host->i_sb);
1282
1283         for (i = 0; i < wc->w_clen; i++) {
1284                 desc = &wc->w_desc[i];
1285
1286                 /*
1287                  * We have to make sure that the total write passed in
1288                  * doesn't extend past a single cluster.
1289                  */
1290                 local_len = len;
1291                 cluster_off = pos & (osb->s_clustersize - 1);
1292                 if ((cluster_off + local_len) > osb->s_clustersize)
1293                         local_len = osb->s_clustersize - cluster_off;
1294
1295                 ret = ocfs2_write_cluster(mapping, desc->c_phys,
1296                                           desc->c_unwritten,
1297                                           desc->c_needs_zero,
1298                                           data_ac, meta_ac,
1299                                           wc, desc->c_cpos, pos, local_len);
1300                 if (ret) {
1301                         mlog_errno(ret);
1302                         goto out;
1303                 }
1304
1305                 len -= local_len;
1306                 pos += local_len;
1307         }
1308
1309         ret = 0;
1310 out:
1311         return ret;
1312 }
1313
1314 /*
1315  * ocfs2_write_end() wants to know which parts of the target page it
1316  * should complete the write on. It's easiest to compute them ahead of
1317  * time when a more complete view of the write is available.
1318  */
1319 static void ocfs2_set_target_boundaries(struct ocfs2_super *osb,
1320                                         struct ocfs2_write_ctxt *wc,
1321                                         loff_t pos, unsigned len, int alloc)
1322 {
1323         struct ocfs2_write_cluster_desc *desc;
1324
1325         wc->w_target_from = pos & (PAGE_CACHE_SIZE - 1);
1326         wc->w_target_to = wc->w_target_from + len;
1327
1328         if (alloc == 0)
1329                 return;
1330
1331         /*
1332          * Allocating write - we may have different boundaries based
1333          * on page size and cluster size.
1334          *
1335          * NOTE: We can no longer compute one value from the other as
1336          * the actual write length and user provided length may be
1337          * different.
1338          */
1339
1340         if (wc->w_large_pages) {
1341                 /*
1342                  * We only care about the 1st and last cluster within
1343                  * our range and whether they should be zero'd or not. Either
1344                  * value may be extended out to the start/end of a
1345                  * newly allocated cluster.
1346                  */
1347                 desc = &wc->w_desc[0];
1348                 if (desc->c_needs_zero)
1349                         ocfs2_figure_cluster_boundaries(osb,
1350                                                         desc->c_cpos,
1351                                                         &wc->w_target_from,
1352                                                         NULL);
1353
1354                 desc = &wc->w_desc[wc->w_clen - 1];
1355                 if (desc->c_needs_zero)
1356                         ocfs2_figure_cluster_boundaries(osb,
1357                                                         desc->c_cpos,
1358                                                         NULL,
1359                                                         &wc->w_target_to);
1360         } else {
1361                 wc->w_target_from = 0;
1362                 wc->w_target_to = PAGE_CACHE_SIZE;
1363         }
1364 }
1365
1366 /*
1367  * Populate each single-cluster write descriptor in the write context
1368  * with information about the i/o to be done.
1369  *
1370  * Returns the number of clusters that will have to be allocated, as
1371  * well as a worst case estimate of the number of extent records that
1372  * would have to be created during a write to an unwritten region.
1373  */
1374 static int ocfs2_populate_write_desc(struct inode *inode,
1375                                      struct ocfs2_write_ctxt *wc,
1376                                      unsigned int *clusters_to_alloc,
1377                                      unsigned int *extents_to_split)
1378 {
1379         int ret;
1380         struct ocfs2_write_cluster_desc *desc;
1381         unsigned int num_clusters = 0;
1382         unsigned int ext_flags = 0;
1383         u32 phys = 0;
1384         int i;
1385
1386         *clusters_to_alloc = 0;
1387         *extents_to_split = 0;
1388
1389         for (i = 0; i < wc->w_clen; i++) {
1390                 desc = &wc->w_desc[i];
1391                 desc->c_cpos = wc->w_cpos + i;
1392
1393                 if (num_clusters == 0) {
1394                         /*
1395                          * Need to look up the next extent record.
1396                          */
1397                         ret = ocfs2_get_clusters(inode, desc->c_cpos, &phys,
1398                                                  &num_clusters, &ext_flags);
1399                         if (ret) {
1400                                 mlog_errno(ret);
1401                                 goto out;
1402                         }
1403
1404                         /* We should already CoW the refcountd extent. */
1405                         BUG_ON(ext_flags & OCFS2_EXT_REFCOUNTED);
1406
1407                         /*
1408                          * Assume worst case - that we're writing in
1409                          * the middle of the extent.
1410                          *
1411                          * We can assume that the write proceeds from
1412                          * left to right, in which case the extent
1413                          * insert code is smart enough to coalesce the
1414                          * next splits into the previous records created.
1415                          */
1416                         if (ext_flags & OCFS2_EXT_UNWRITTEN)
1417                                 *extents_to_split = *extents_to_split + 2;
1418                 } else if (phys) {
1419                         /*
1420                          * Only increment phys if it doesn't describe
1421                          * a hole.
1422                          */
1423                         phys++;
1424                 }
1425
1426                 /*
1427                  * If w_first_new_cpos is < UINT_MAX, we have a non-sparse
1428                  * file that got extended.  w_first_new_cpos tells us
1429                  * where the newly allocated clusters are so we can
1430                  * zero them.
1431                  */
1432                 if (desc->c_cpos >= wc->w_first_new_cpos) {
1433                         BUG_ON(phys == 0);
1434                         desc->c_needs_zero = 1;
1435                 }
1436
1437                 desc->c_phys = phys;
1438                 if (phys == 0) {
1439                         desc->c_new = 1;
1440                         desc->c_needs_zero = 1;
1441                         *clusters_to_alloc = *clusters_to_alloc + 1;
1442                 }
1443
1444                 if (ext_flags & OCFS2_EXT_UNWRITTEN) {
1445                         desc->c_unwritten = 1;
1446                         desc->c_needs_zero = 1;
1447                 }
1448
1449                 num_clusters--;
1450         }
1451
1452         ret = 0;
1453 out:
1454         return ret;
1455 }
1456
1457 static int ocfs2_write_begin_inline(struct address_space *mapping,
1458                                     struct inode *inode,
1459                                     struct ocfs2_write_ctxt *wc)
1460 {
1461         int ret;
1462         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
1463         struct page *page;
1464         handle_t *handle;
1465         struct ocfs2_dinode *di = (struct ocfs2_dinode *)wc->w_di_bh->b_data;
1466
1467         page = find_or_create_page(mapping, 0, GFP_NOFS);
1468         if (!page) {
1469                 ret = -ENOMEM;
1470                 mlog_errno(ret);
1471                 goto out;
1472         }
1473         /*
1474          * If we don't set w_num_pages then this page won't get unlocked
1475          * and freed on cleanup of the write context.
1476          */
1477         wc->w_pages[0] = wc->w_target_page = page;
1478         wc->w_num_pages = 1;
1479
1480         handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
1481         if (IS_ERR(handle)) {
1482                 ret = PTR_ERR(handle);
1483                 mlog_errno(ret);
1484                 goto out;
1485         }
1486
1487         ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), wc->w_di_bh,
1488                                       OCFS2_JOURNAL_ACCESS_WRITE);
1489         if (ret) {
1490                 ocfs2_commit_trans(osb, handle);
1491
1492                 mlog_errno(ret);
1493                 goto out;
1494         }
1495
1496         if (!(OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL))
1497                 ocfs2_set_inode_data_inline(inode, di);
1498
1499         if (!PageUptodate(page)) {
1500                 ret = ocfs2_read_inline_data(inode, page, wc->w_di_bh);
1501                 if (ret) {
1502                         ocfs2_commit_trans(osb, handle);
1503
1504                         goto out;
1505                 }
1506         }
1507
1508         wc->w_handle = handle;
1509 out:
1510         return ret;
1511 }
1512
1513 int ocfs2_size_fits_inline_data(struct buffer_head *di_bh, u64 new_size)
1514 {
1515         struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
1516
1517         if (new_size <= le16_to_cpu(di->id2.i_data.id_count))
1518                 return 1;
1519         return 0;
1520 }
1521
1522 static int ocfs2_try_to_write_inline_data(struct address_space *mapping,
1523                                           struct inode *inode, loff_t pos,
1524                                           unsigned len, struct page *mmap_page,
1525                                           struct ocfs2_write_ctxt *wc)
1526 {
1527         int ret, written = 0;
1528         loff_t end = pos + len;
1529         struct ocfs2_inode_info *oi = OCFS2_I(inode);
1530         struct ocfs2_dinode *di = NULL;
1531
1532         trace_ocfs2_try_to_write_inline_data((unsigned long long)oi->ip_blkno,
1533                                              len, (unsigned long long)pos,
1534                                              oi->ip_dyn_features);
1535
1536         /*
1537          * Handle inodes which already have inline data 1st.
1538          */
1539         if (oi->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
1540                 if (mmap_page == NULL &&
1541                     ocfs2_size_fits_inline_data(wc->w_di_bh, end))
1542                         goto do_inline_write;
1543
1544                 /*
1545                  * The write won't fit - we have to give this inode an
1546                  * inline extent list now.
1547                  */
1548                 ret = ocfs2_convert_inline_data_to_extents(inode, wc->w_di_bh);
1549                 if (ret)
1550                         mlog_errno(ret);
1551                 goto out;
1552         }
1553
1554         /*
1555          * Check whether the inode can accept inline data.
1556          */
1557         if (oi->ip_clusters != 0 || i_size_read(inode) != 0)
1558                 return 0;
1559
1560         /*
1561          * Check whether the write can fit.
1562          */
1563         di = (struct ocfs2_dinode *)wc->w_di_bh->b_data;
1564         if (mmap_page ||
1565             end > ocfs2_max_inline_data_with_xattr(inode->i_sb, di))
1566                 return 0;
1567
1568 do_inline_write:
1569         ret = ocfs2_write_begin_inline(mapping, inode, wc);
1570         if (ret) {
1571                 mlog_errno(ret);
1572                 goto out;
1573         }
1574
1575         /*
1576          * This signals to the caller that the data can be written
1577          * inline.
1578          */
1579         written = 1;
1580 out:
1581         return written ? written : ret;
1582 }
1583
1584 /*
1585  * This function only does anything for file systems which can't
1586  * handle sparse files.
1587  *
1588  * What we want to do here is fill in any hole between the current end
1589  * of allocation and the end of our write. That way the rest of the
1590  * write path can treat it as an non-allocating write, which has no
1591  * special case code for sparse/nonsparse files.
1592  */
1593 static int ocfs2_expand_nonsparse_inode(struct inode *inode,
1594                                         struct buffer_head *di_bh,
1595                                         loff_t pos, unsigned len,
1596                                         struct ocfs2_write_ctxt *wc)
1597 {
1598         int ret;
1599         loff_t newsize = pos + len;
1600
1601         BUG_ON(ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)));
1602
1603         if (newsize <= i_size_read(inode))
1604                 return 0;
1605
1606         ret = ocfs2_extend_no_holes(inode, di_bh, newsize, pos);
1607         if (ret)
1608                 mlog_errno(ret);
1609
1610         wc->w_first_new_cpos =
1611                 ocfs2_clusters_for_bytes(inode->i_sb, i_size_read(inode));
1612
1613         return ret;
1614 }
1615
1616 static int ocfs2_zero_tail(struct inode *inode, struct buffer_head *di_bh,
1617                            loff_t pos)
1618 {
1619         int ret = 0;
1620
1621         BUG_ON(!ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)));
1622         if (pos > i_size_read(inode))
1623                 ret = ocfs2_zero_extend(inode, di_bh, pos);
1624
1625         return ret;
1626 }
1627
1628 /*
1629  * Try to flush truncate logs if we can free enough clusters from it.
1630  * As for return value, "< 0" means error, "0" no space and "1" means
1631  * we have freed enough spaces and let the caller try to allocate again.
1632  */
1633 static int ocfs2_try_to_free_truncate_log(struct ocfs2_super *osb,
1634                                           unsigned int needed)
1635 {
1636         tid_t target;
1637         int ret = 0;
1638         unsigned int truncated_clusters;
1639
1640         mutex_lock(&osb->osb_tl_inode->i_mutex);
1641         truncated_clusters = osb->truncated_clusters;
1642         mutex_unlock(&osb->osb_tl_inode->i_mutex);
1643
1644         /*
1645          * Check whether we can succeed in allocating if we free
1646          * the truncate log.
1647          */
1648         if (truncated_clusters < needed)
1649                 goto out;
1650
1651         ret = ocfs2_flush_truncate_log(osb);
1652         if (ret) {
1653                 mlog_errno(ret);
1654                 goto out;
1655         }
1656
1657         if (jbd2_journal_start_commit(osb->journal->j_journal, &target)) {
1658                 jbd2_log_wait_commit(osb->journal->j_journal, target);
1659                 ret = 1;
1660         }
1661 out:
1662         return ret;
1663 }
1664
1665 int ocfs2_write_begin_nolock(struct file *filp,
1666                              struct address_space *mapping,
1667                              loff_t pos, unsigned len, unsigned flags,
1668                              struct page **pagep, void **fsdata,
1669                              struct buffer_head *di_bh, struct page *mmap_page)
1670 {
1671         int ret, cluster_of_pages, credits = OCFS2_INODE_UPDATE_CREDITS;
1672         unsigned int clusters_to_alloc, extents_to_split, clusters_need = 0;
1673         struct ocfs2_write_ctxt *wc;
1674         struct inode *inode = mapping->host;
1675         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
1676         struct ocfs2_dinode *di;
1677         struct ocfs2_alloc_context *data_ac = NULL;
1678         struct ocfs2_alloc_context *meta_ac = NULL;
1679         handle_t *handle;
1680         struct ocfs2_extent_tree et;
1681         int try_free = 1, ret1;
1682
1683 try_again:
1684         ret = ocfs2_alloc_write_ctxt(&wc, osb, pos, len, di_bh);
1685         if (ret) {
1686                 mlog_errno(ret);
1687                 return ret;
1688         }
1689
1690         if (ocfs2_supports_inline_data(osb)) {
1691                 ret = ocfs2_try_to_write_inline_data(mapping, inode, pos, len,
1692                                                      mmap_page, wc);
1693                 if (ret == 1) {
1694                         ret = 0;
1695                         goto success;
1696                 }
1697                 if (ret < 0) {
1698                         mlog_errno(ret);
1699                         goto out;
1700                 }
1701         }
1702
1703         if (ocfs2_sparse_alloc(osb))
1704                 ret = ocfs2_zero_tail(inode, di_bh, pos);
1705         else
1706                 ret = ocfs2_expand_nonsparse_inode(inode, di_bh, pos, len,
1707                                                    wc);
1708         if (ret) {
1709                 mlog_errno(ret);
1710                 goto out;
1711         }
1712
1713         ret = ocfs2_check_range_for_refcount(inode, pos, len);
1714         if (ret < 0) {
1715                 mlog_errno(ret);
1716                 goto out;
1717         } else if (ret == 1) {
1718                 clusters_need = wc->w_clen;
1719                 ret = ocfs2_refcount_cow(inode, filp, di_bh,
1720                                          wc->w_cpos, wc->w_clen, UINT_MAX);
1721                 if (ret) {
1722                         mlog_errno(ret);
1723                         goto out;
1724                 }
1725         }
1726
1727         ret = ocfs2_populate_write_desc(inode, wc, &clusters_to_alloc,
1728                                         &extents_to_split);
1729         if (ret) {
1730                 mlog_errno(ret);
1731                 goto out;
1732         }
1733         clusters_need += clusters_to_alloc;
1734
1735         di = (struct ocfs2_dinode *)wc->w_di_bh->b_data;
1736
1737         trace_ocfs2_write_begin_nolock(
1738                         (unsigned long long)OCFS2_I(inode)->ip_blkno,
1739                         (long long)i_size_read(inode),
1740                         le32_to_cpu(di->i_clusters),
1741                         pos, len, flags, mmap_page,
1742                         clusters_to_alloc, extents_to_split);
1743
1744         /*
1745          * We set w_target_from, w_target_to here so that
1746          * ocfs2_write_end() knows which range in the target page to
1747          * write out. An allocation requires that we write the entire
1748          * cluster range.
1749          */
1750         if (clusters_to_alloc || extents_to_split) {
1751                 /*
1752                  * XXX: We are stretching the limits of
1753                  * ocfs2_lock_allocators(). It greatly over-estimates
1754                  * the work to be done.
1755                  */
1756                 ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode),
1757                                               wc->w_di_bh);
1758                 ret = ocfs2_lock_allocators(inode, &et,
1759                                             clusters_to_alloc, extents_to_split,
1760                                             &data_ac, &meta_ac);
1761                 if (ret) {
1762                         mlog_errno(ret);
1763                         goto out;
1764                 }
1765
1766                 if (data_ac)
1767                         data_ac->ac_resv = &OCFS2_I(inode)->ip_la_data_resv;
1768
1769                 credits = ocfs2_calc_extend_credits(inode->i_sb,
1770                                                     &di->id2.i_list,
1771                                                     clusters_to_alloc);
1772
1773         }
1774
1775         /*
1776          * We have to zero sparse allocated clusters, unwritten extent clusters,
1777          * and non-sparse clusters we just extended.  For non-sparse writes,
1778          * we know zeros will only be needed in the first and/or last cluster.
1779          */
1780         if (clusters_to_alloc || extents_to_split ||
1781             (wc->w_clen && (wc->w_desc[0].c_needs_zero ||
1782                             wc->w_desc[wc->w_clen - 1].c_needs_zero)))
1783                 cluster_of_pages = 1;
1784         else
1785                 cluster_of_pages = 0;
1786
1787         ocfs2_set_target_boundaries(osb, wc, pos, len, cluster_of_pages);
1788
1789         handle = ocfs2_start_trans(osb, credits);
1790         if (IS_ERR(handle)) {
1791                 ret = PTR_ERR(handle);
1792                 mlog_errno(ret);
1793                 goto out;
1794         }
1795
1796         wc->w_handle = handle;
1797
1798         if (clusters_to_alloc) {
1799                 ret = dquot_alloc_space_nodirty(inode,
1800                         ocfs2_clusters_to_bytes(osb->sb, clusters_to_alloc));
1801                 if (ret)
1802                         goto out_commit;
1803         }
1804         /*
1805          * We don't want this to fail in ocfs2_write_end(), so do it
1806          * here.
1807          */
1808         ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), wc->w_di_bh,
1809                                       OCFS2_JOURNAL_ACCESS_WRITE);
1810         if (ret) {
1811                 mlog_errno(ret);
1812                 goto out_quota;
1813         }
1814
1815         /*
1816          * Fill our page array first. That way we've grabbed enough so
1817          * that we can zero and flush if we error after adding the
1818          * extent.
1819          */
1820         ret = ocfs2_grab_pages_for_write(mapping, wc, wc->w_cpos, pos, len,
1821                                          cluster_of_pages, mmap_page);
1822         if (ret) {
1823                 mlog_errno(ret);
1824                 goto out_quota;
1825         }
1826
1827         ret = ocfs2_write_cluster_by_desc(mapping, data_ac, meta_ac, wc, pos,
1828                                           len);
1829         if (ret) {
1830                 mlog_errno(ret);
1831                 goto out_quota;
1832         }
1833
1834         if (data_ac)
1835                 ocfs2_free_alloc_context(data_ac);
1836         if (meta_ac)
1837                 ocfs2_free_alloc_context(meta_ac);
1838
1839 success:
1840         *pagep = wc->w_target_page;
1841         *fsdata = wc;
1842         return 0;
1843 out_quota:
1844         if (clusters_to_alloc)
1845                 dquot_free_space(inode,
1846                           ocfs2_clusters_to_bytes(osb->sb, clusters_to_alloc));
1847 out_commit:
1848         ocfs2_commit_trans(osb, handle);
1849
1850 out:
1851         ocfs2_free_write_ctxt(wc);
1852
1853         if (data_ac)
1854                 ocfs2_free_alloc_context(data_ac);
1855         if (meta_ac)
1856                 ocfs2_free_alloc_context(meta_ac);
1857
1858         if (ret == -ENOSPC && try_free) {
1859                 /*
1860                  * Try to free some truncate log so that we can have enough
1861                  * clusters to allocate.
1862                  */
1863                 try_free = 0;
1864
1865                 ret1 = ocfs2_try_to_free_truncate_log(osb, clusters_need);
1866                 if (ret1 == 1)
1867                         goto try_again;
1868
1869                 if (ret1 < 0)
1870                         mlog_errno(ret1);
1871         }
1872
1873         return ret;
1874 }
1875
1876 static int ocfs2_write_begin(struct file *file, struct address_space *mapping,
1877                              loff_t pos, unsigned len, unsigned flags,
1878                              struct page **pagep, void **fsdata)
1879 {
1880         int ret;
1881         struct buffer_head *di_bh = NULL;
1882         struct inode *inode = mapping->host;
1883
1884         ret = ocfs2_inode_lock(inode, &di_bh, 1);
1885         if (ret) {
1886                 mlog_errno(ret);
1887                 return ret;
1888         }
1889
1890         /*
1891          * Take alloc sem here to prevent concurrent lookups. That way
1892          * the mapping, zeroing and tree manipulation within
1893          * ocfs2_write() will be safe against ->readpage(). This
1894          * should also serve to lock out allocation from a shared
1895          * writeable region.
1896          */
1897         down_write(&OCFS2_I(inode)->ip_alloc_sem);
1898
1899         ret = ocfs2_write_begin_nolock(file, mapping, pos, len, flags, pagep,
1900                                        fsdata, di_bh, NULL);
1901         if (ret) {
1902                 mlog_errno(ret);
1903                 goto out_fail;
1904         }
1905
1906         brelse(di_bh);
1907
1908         return 0;
1909
1910 out_fail:
1911         up_write(&OCFS2_I(inode)->ip_alloc_sem);
1912
1913         brelse(di_bh);
1914         ocfs2_inode_unlock(inode, 1);
1915
1916         return ret;
1917 }
1918
1919 static void ocfs2_write_end_inline(struct inode *inode, loff_t pos,
1920                                    unsigned len, unsigned *copied,
1921                                    struct ocfs2_dinode *di,
1922                                    struct ocfs2_write_ctxt *wc)
1923 {
1924         void *kaddr;
1925
1926         if (unlikely(*copied < len)) {
1927                 if (!PageUptodate(wc->w_target_page)) {
1928                         *copied = 0;
1929                         return;
1930                 }
1931         }
1932
1933         kaddr = kmap_atomic(wc->w_target_page, KM_USER0);
1934         memcpy(di->id2.i_data.id_data + pos, kaddr + pos, *copied);
1935         kunmap_atomic(kaddr, KM_USER0);
1936
1937         trace_ocfs2_write_end_inline(
1938              (unsigned long long)OCFS2_I(inode)->ip_blkno,
1939              (unsigned long long)pos, *copied,
1940              le16_to_cpu(di->id2.i_data.id_count),
1941              le16_to_cpu(di->i_dyn_features));
1942 }
1943
1944 int ocfs2_write_end_nolock(struct address_space *mapping,
1945                            loff_t pos, unsigned len, unsigned copied,
1946                            struct page *page, void *fsdata)
1947 {
1948         int i;
1949         unsigned from, to, start = pos & (PAGE_CACHE_SIZE - 1);
1950         struct inode *inode = mapping->host;
1951         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
1952         struct ocfs2_write_ctxt *wc = fsdata;
1953         struct ocfs2_dinode *di = (struct ocfs2_dinode *)wc->w_di_bh->b_data;
1954         handle_t *handle = wc->w_handle;
1955         struct page *tmppage;
1956
1957         if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
1958                 ocfs2_write_end_inline(inode, pos, len, &copied, di, wc);
1959                 goto out_write_size;
1960         }
1961
1962         if (unlikely(copied < len)) {
1963                 if (!PageUptodate(wc->w_target_page))
1964                         copied = 0;
1965
1966                 ocfs2_zero_new_buffers(wc->w_target_page, start+copied,
1967                                        start+len);
1968         }
1969         flush_dcache_page(wc->w_target_page);
1970
1971         for(i = 0; i < wc->w_num_pages; i++) {
1972                 tmppage = wc->w_pages[i];
1973
1974                 if (tmppage == wc->w_target_page) {
1975                         from = wc->w_target_from;
1976                         to = wc->w_target_to;
1977
1978                         BUG_ON(from > PAGE_CACHE_SIZE ||
1979                                to > PAGE_CACHE_SIZE ||
1980                                to < from);
1981                 } else {
1982                         /*
1983                          * Pages adjacent to the target (if any) imply
1984                          * a hole-filling write in which case we want
1985                          * to flush their entire range.
1986                          */
1987                         from = 0;
1988                         to = PAGE_CACHE_SIZE;
1989                 }
1990
1991                 if (page_has_buffers(tmppage)) {
1992                         if (ocfs2_should_order_data(inode))
1993                                 ocfs2_jbd2_file_inode(wc->w_handle, inode);
1994                         block_commit_write(tmppage, from, to);
1995                 }
1996         }
1997
1998 out_write_size:
1999         pos += copied;
2000         if (pos > inode->i_size) {
2001                 i_size_write(inode, pos);
2002                 mark_inode_dirty(inode);
2003         }
2004         inode->i_blocks = ocfs2_inode_sector_count(inode);
2005         di->i_size = cpu_to_le64((u64)i_size_read(inode));
2006         inode->i_mtime = inode->i_ctime = CURRENT_TIME;
2007         di->i_mtime = di->i_ctime = cpu_to_le64(inode->i_mtime.tv_sec);
2008         di->i_mtime_nsec = di->i_ctime_nsec = cpu_to_le32(inode->i_mtime.tv_nsec);
2009         ocfs2_journal_dirty(handle, wc->w_di_bh);
2010
2011         ocfs2_commit_trans(osb, handle);
2012
2013         ocfs2_run_deallocs(osb, &wc->w_dealloc);
2014
2015         ocfs2_free_write_ctxt(wc);
2016
2017         return copied;
2018 }
2019
2020 static int ocfs2_write_end(struct file *file, struct address_space *mapping,
2021                            loff_t pos, unsigned len, unsigned copied,
2022                            struct page *page, void *fsdata)
2023 {
2024         int ret;
2025         struct inode *inode = mapping->host;
2026
2027         ret = ocfs2_write_end_nolock(mapping, pos, len, copied, page, fsdata);
2028
2029         up_write(&OCFS2_I(inode)->ip_alloc_sem);
2030         ocfs2_inode_unlock(inode, 1);
2031
2032         return ret;
2033 }
2034
2035 const struct address_space_operations ocfs2_aops = {
2036         .readpage               = ocfs2_readpage,
2037         .readpages              = ocfs2_readpages,
2038         .writepage              = ocfs2_writepage,
2039         .write_begin            = ocfs2_write_begin,
2040         .write_end              = ocfs2_write_end,
2041         .bmap                   = ocfs2_bmap,
2042         .direct_IO              = ocfs2_direct_IO,
2043         .invalidatepage         = ocfs2_invalidatepage,
2044         .releasepage            = ocfs2_releasepage,
2045         .migratepage            = buffer_migrate_page,
2046         .is_partially_uptodate  = block_is_partially_uptodate,
2047         .error_remove_page      = generic_error_remove_page,
2048 };