daea0359e9740263a525cec5c7f645e456d9a909
[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 #define MLOG_MASK_PREFIX ML_FILE_IO
33 #include <cluster/masklog.h>
34
35 #include "ocfs2.h"
36
37 #include "alloc.h"
38 #include "aops.h"
39 #include "dlmglue.h"
40 #include "extent_map.h"
41 #include "file.h"
42 #include "inode.h"
43 #include "journal.h"
44 #include "suballoc.h"
45 #include "super.h"
46 #include "symlink.h"
47 #include "refcounttree.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         mlog_entry("(0x%p, %llu, 0x%p, %d)\n", inode,
63                    (unsigned long long)iblock, bh_result, create);
64
65         BUG_ON(ocfs2_inode_is_fast_symlink(inode));
66
67         if ((iblock << inode->i_sb->s_blocksize_bits) > PATH_MAX + 1) {
68                 mlog(ML_ERROR, "block offset > PATH_MAX: %llu",
69                      (unsigned long long)iblock);
70                 goto bail;
71         }
72
73         status = ocfs2_read_inode_block(inode, &bh);
74         if (status < 0) {
75                 mlog_errno(status);
76                 goto bail;
77         }
78         fe = (struct ocfs2_dinode *) bh->b_data;
79
80         if ((u64)iblock >= ocfs2_clusters_to_blocks(inode->i_sb,
81                                                     le32_to_cpu(fe->i_clusters))) {
82                 mlog(ML_ERROR, "block offset is outside the allocated size: "
83                      "%llu\n", (unsigned long long)iblock);
84                 goto bail;
85         }
86
87         /* We don't use the page cache to create symlink data, so if
88          * need be, copy it over from the buffer cache. */
89         if (!buffer_uptodate(bh_result) && ocfs2_inode_is_new(inode)) {
90                 u64 blkno = le64_to_cpu(fe->id2.i_list.l_recs[0].e_blkno) +
91                             iblock;
92                 buffer_cache_bh = sb_getblk(osb->sb, blkno);
93                 if (!buffer_cache_bh) {
94                         mlog(ML_ERROR, "couldn't getblock for symlink!\n");
95                         goto bail;
96                 }
97
98                 /* we haven't locked out transactions, so a commit
99                  * could've happened. Since we've got a reference on
100                  * the bh, even if it commits while we're doing the
101                  * copy, the data is still good. */
102                 if (buffer_jbd(buffer_cache_bh)
103                     && ocfs2_inode_is_new(inode)) {
104                         kaddr = kmap_atomic(bh_result->b_page, KM_USER0);
105                         if (!kaddr) {
106                                 mlog(ML_ERROR, "couldn't kmap!\n");
107                                 goto bail;
108                         }
109                         memcpy(kaddr + (bh_result->b_size * iblock),
110                                buffer_cache_bh->b_data,
111                                bh_result->b_size);
112                         kunmap_atomic(kaddr, KM_USER0);
113                         set_buffer_uptodate(bh_result);
114                 }
115                 brelse(buffer_cache_bh);
116         }
117
118         map_bh(bh_result, inode->i_sb,
119                le64_to_cpu(fe->id2.i_list.l_recs[0].e_blkno) + iblock);
120
121         err = 0;
122
123 bail:
124         brelse(bh);
125
126         mlog_exit(err);
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         mlog_entry("(0x%p, %llu, 0x%p, %d)\n", inode,
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         mlog(0, "Inode %lu, past_eof = %llu\n", inode->i_ino,
203              (unsigned long long)past_eof);
204         if (create && (iblock >= past_eof))
205                 set_buffer_new(bh_result);
206
207 bail:
208         if (err < 0)
209                 err = -EIO;
210
211         mlog_exit(err);
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         mlog_entry("(0x%p, %lu)\n", file, (page ? page->index : 0));
282
283         ret = ocfs2_inode_lock_with_page(inode, NULL, 0, page);
284         if (ret != 0) {
285                 if (ret == AOP_TRUNCATED_PAGE)
286                         unlock = 0;
287                 mlog_errno(ret);
288                 goto out;
289         }
290
291         if (down_read_trylock(&oi->ip_alloc_sem) == 0) {
292                 ret = AOP_TRUNCATED_PAGE;
293                 goto out_inode_unlock;
294         }
295
296         /*
297          * i_size might have just been updated as we grabed the meta lock.  We
298          * might now be discovering a truncate that hit on another node.
299          * block_read_full_page->get_block freaks out if it is asked to read
300          * beyond the end of a file, so we check here.  Callers
301          * (generic_file_read, vm_ops->fault) are clever enough to check i_size
302          * and notice that the page they just read isn't needed.
303          *
304          * XXX sys_readahead() seems to get that wrong?
305          */
306         if (start >= i_size_read(inode)) {
307                 zero_user(page, 0, PAGE_SIZE);
308                 SetPageUptodate(page);
309                 ret = 0;
310                 goto out_alloc;
311         }
312
313         if (oi->ip_dyn_features & OCFS2_INLINE_DATA_FL)
314                 ret = ocfs2_readpage_inline(inode, page);
315         else
316                 ret = block_read_full_page(page, ocfs2_get_block);
317         unlock = 0;
318
319 out_alloc:
320         up_read(&OCFS2_I(inode)->ip_alloc_sem);
321 out_inode_unlock:
322         ocfs2_inode_unlock(inode, 0);
323 out:
324         if (unlock)
325                 unlock_page(page);
326         mlog_exit(ret);
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         int ret;
400
401         mlog_entry("(0x%p)\n", page);
402
403         ret = block_write_full_page(page, ocfs2_get_block, wbc);
404
405         mlog_exit(ret);
406
407         return ret;
408 }
409
410 /* Taken from ext3. We don't necessarily need the full blown
411  * functionality yet, but IMHO it's better to cut and paste the whole
412  * thing so we can avoid introducing our own bugs (and easily pick up
413  * their fixes when they happen) --Mark */
414 int walk_page_buffers(  handle_t *handle,
415                         struct buffer_head *head,
416                         unsigned from,
417                         unsigned to,
418                         int *partial,
419                         int (*fn)(      handle_t *handle,
420                                         struct buffer_head *bh))
421 {
422         struct buffer_head *bh;
423         unsigned block_start, block_end;
424         unsigned blocksize = head->b_size;
425         int err, ret = 0;
426         struct buffer_head *next;
427
428         for (   bh = head, block_start = 0;
429                 ret == 0 && (bh != head || !block_start);
430                 block_start = block_end, bh = next)
431         {
432                 next = bh->b_this_page;
433                 block_end = block_start + blocksize;
434                 if (block_end <= from || block_start >= to) {
435                         if (partial && !buffer_uptodate(bh))
436                                 *partial = 1;
437                         continue;
438                 }
439                 err = (*fn)(handle, bh);
440                 if (!ret)
441                         ret = err;
442         }
443         return ret;
444 }
445
446 static sector_t ocfs2_bmap(struct address_space *mapping, sector_t block)
447 {
448         sector_t status;
449         u64 p_blkno = 0;
450         int err = 0;
451         struct inode *inode = mapping->host;
452
453         mlog_entry("(block = %llu)\n", (unsigned long long)block);
454
455         /* We don't need to lock journal system files, since they aren't
456          * accessed concurrently from multiple nodes.
457          */
458         if (!INODE_JOURNAL(inode)) {
459                 err = ocfs2_inode_lock(inode, NULL, 0);
460                 if (err) {
461                         if (err != -ENOENT)
462                                 mlog_errno(err);
463                         goto bail;
464                 }
465                 down_read(&OCFS2_I(inode)->ip_alloc_sem);
466         }
467
468         if (!(OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL))
469                 err = ocfs2_extent_map_get_blocks(inode, block, &p_blkno, NULL,
470                                                   NULL);
471
472         if (!INODE_JOURNAL(inode)) {
473                 up_read(&OCFS2_I(inode)->ip_alloc_sem);
474                 ocfs2_inode_unlock(inode, 0);
475         }
476
477         if (err) {
478                 mlog(ML_ERROR, "get_blocks() failed, block = %llu\n",
479                      (unsigned long long)block);
480                 mlog_errno(err);
481                 goto bail;
482         }
483
484 bail:
485         status = err ? 0 : p_blkno;
486
487         mlog_exit((int)status);
488
489         return status;
490 }
491
492 /*
493  * TODO: Make this into a generic get_blocks function.
494  *
495  * From do_direct_io in direct-io.c:
496  *  "So what we do is to permit the ->get_blocks function to populate
497  *   bh.b_size with the size of IO which is permitted at this offset and
498  *   this i_blkbits."
499  *
500  * This function is called directly from get_more_blocks in direct-io.c.
501  *
502  * called like this: dio->get_blocks(dio->inode, fs_startblk,
503  *                                      fs_count, map_bh, dio->rw == WRITE);
504  *
505  * Note that we never bother to allocate blocks here, and thus ignore the
506  * create argument.
507  */
508 static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock,
509                                      struct buffer_head *bh_result, int create)
510 {
511         int ret;
512         u64 p_blkno, inode_blocks, contig_blocks;
513         unsigned int ext_flags;
514         unsigned char blocksize_bits = inode->i_sb->s_blocksize_bits;
515         unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
516
517         /* This function won't even be called if the request isn't all
518          * nicely aligned and of the right size, so there's no need
519          * for us to check any of that. */
520
521         inode_blocks = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));
522
523         /* This figures out the size of the next contiguous block, and
524          * our logical offset */
525         ret = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno,
526                                           &contig_blocks, &ext_flags);
527         if (ret) {
528                 mlog(ML_ERROR, "get_blocks() failed iblock=%llu\n",
529                      (unsigned long long)iblock);
530                 ret = -EIO;
531                 goto bail;
532         }
533
534         /* We should already CoW the refcounted extent in case of create. */
535         BUG_ON(create && (ext_flags & OCFS2_EXT_REFCOUNTED));
536
537         /*
538          * get_more_blocks() expects us to describe a hole by clearing
539          * the mapped bit on bh_result().
540          *
541          * Consider an unwritten extent as a hole.
542          */
543         if (p_blkno && !(ext_flags & OCFS2_EXT_UNWRITTEN))
544                 map_bh(bh_result, inode->i_sb, p_blkno);
545         else
546                 clear_buffer_mapped(bh_result);
547
548         /* make sure we don't map more than max_blocks blocks here as
549            that's all the kernel will handle at this point. */
550         if (max_blocks < contig_blocks)
551                 contig_blocks = max_blocks;
552         bh_result->b_size = contig_blocks << blocksize_bits;
553 bail:
554         return ret;
555 }
556
557 /*
558  * ocfs2_dio_end_io is called by the dio core when a dio is finished.  We're
559  * particularly interested in the aio/dio case.  Like the core uses
560  * i_alloc_sem, we use the rw_lock DLM lock to protect io on one node from
561  * truncation on another.
562  */
563 static void ocfs2_dio_end_io(struct kiocb *iocb,
564                              loff_t offset,
565                              ssize_t bytes,
566                              void *private,
567                              int ret,
568                              bool is_async)
569 {
570         struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
571         int level;
572
573         /* this io's submitter should not have unlocked this before we could */
574         BUG_ON(!ocfs2_iocb_is_rw_locked(iocb));
575
576         if (ocfs2_iocb_is_sem_locked(iocb)) {
577                 up_read(&inode->i_alloc_sem);
578                 ocfs2_iocb_clear_sem_locked(iocb);
579         }
580
581         ocfs2_iocb_clear_rw_locked(iocb);
582
583         level = ocfs2_iocb_rw_locked_level(iocb);
584         ocfs2_rw_unlock(inode, level);
585
586         if (is_async)
587                 aio_complete(iocb, ret, 0);
588 }
589
590 /*
591  * ocfs2_invalidatepage() and ocfs2_releasepage() are shamelessly stolen
592  * from ext3.  PageChecked() bits have been removed as OCFS2 does not
593  * do journalled data.
594  */
595 static void ocfs2_invalidatepage(struct page *page, unsigned long offset)
596 {
597         journal_t *journal = OCFS2_SB(page->mapping->host->i_sb)->journal->j_journal;
598
599         jbd2_journal_invalidatepage(journal, page, offset);
600 }
601
602 static int ocfs2_releasepage(struct page *page, gfp_t wait)
603 {
604         journal_t *journal = OCFS2_SB(page->mapping->host->i_sb)->journal->j_journal;
605
606         if (!page_has_buffers(page))
607                 return 0;
608         return jbd2_journal_try_to_free_buffers(journal, page, wait);
609 }
610
611 static ssize_t ocfs2_direct_IO(int rw,
612                                struct kiocb *iocb,
613                                const struct iovec *iov,
614                                loff_t offset,
615                                unsigned long nr_segs)
616 {
617         struct file *file = iocb->ki_filp;
618         struct inode *inode = file->f_path.dentry->d_inode->i_mapping->host;
619         int ret;
620
621         mlog_entry_void();
622
623         /*
624          * Fallback to buffered I/O if we see an inode without
625          * extents.
626          */
627         if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL)
628                 return 0;
629
630         /* Fallback to buffered I/O if we are appending. */
631         if (i_size_read(inode) <= offset)
632                 return 0;
633
634         ret = __blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev,
635                                    iov, offset, nr_segs,
636                                    ocfs2_direct_IO_get_blocks,
637                                    ocfs2_dio_end_io, NULL, 0);
638
639         mlog_exit(ret);
640         return ret;
641 }
642
643 static void ocfs2_figure_cluster_boundaries(struct ocfs2_super *osb,
644                                             u32 cpos,
645                                             unsigned int *start,
646                                             unsigned int *end)
647 {
648         unsigned int cluster_start = 0, cluster_end = PAGE_CACHE_SIZE;
649
650         if (unlikely(PAGE_CACHE_SHIFT > osb->s_clustersize_bits)) {
651                 unsigned int cpp;
652
653                 cpp = 1 << (PAGE_CACHE_SHIFT - osb->s_clustersize_bits);
654
655                 cluster_start = cpos % cpp;
656                 cluster_start = cluster_start << osb->s_clustersize_bits;
657
658                 cluster_end = cluster_start + osb->s_clustersize;
659         }
660
661         BUG_ON(cluster_start > PAGE_SIZE);
662         BUG_ON(cluster_end > PAGE_SIZE);
663
664         if (start)
665                 *start = cluster_start;
666         if (end)
667                 *end = cluster_end;
668 }
669
670 /*
671  * 'from' and 'to' are the region in the page to avoid zeroing.
672  *
673  * If pagesize > clustersize, this function will avoid zeroing outside
674  * of the cluster boundary.
675  *
676  * from == to == 0 is code for "zero the entire cluster region"
677  */
678 static void ocfs2_clear_page_regions(struct page *page,
679                                      struct ocfs2_super *osb, u32 cpos,
680                                      unsigned from, unsigned to)
681 {
682         void *kaddr;
683         unsigned int cluster_start, cluster_end;
684
685         ocfs2_figure_cluster_boundaries(osb, cpos, &cluster_start, &cluster_end);
686
687         kaddr = kmap_atomic(page, KM_USER0);
688
689         if (from || to) {
690                 if (from > cluster_start)
691                         memset(kaddr + cluster_start, 0, from - cluster_start);
692                 if (to < cluster_end)
693                         memset(kaddr + to, 0, cluster_end - to);
694         } else {
695                 memset(kaddr + cluster_start, 0, cluster_end - cluster_start);
696         }
697
698         kunmap_atomic(kaddr, KM_USER0);
699 }
700
701 /*
702  * Nonsparse file systems fully allocate before we get to the write
703  * code. This prevents ocfs2_write() from tagging the write as an
704  * allocating one, which means ocfs2_map_page_blocks() might try to
705  * read-in the blocks at the tail of our file. Avoid reading them by
706  * testing i_size against each block offset.
707  */
708 static int ocfs2_should_read_blk(struct inode *inode, struct page *page,
709                                  unsigned int block_start)
710 {
711         u64 offset = page_offset(page) + block_start;
712
713         if (ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)))
714                 return 1;
715
716         if (i_size_read(inode) > offset)
717                 return 1;
718
719         return 0;
720 }
721
722 /*
723  * Some of this taken from __block_write_begin(). We already have our
724  * mapping by now though, and the entire write will be allocating or
725  * it won't, so not much need to use BH_New.
726  *
727  * This will also skip zeroing, which is handled externally.
728  */
729 int ocfs2_map_page_blocks(struct page *page, u64 *p_blkno,
730                           struct inode *inode, unsigned int from,
731                           unsigned int to, int new)
732 {
733         int ret = 0;
734         struct buffer_head *head, *bh, *wait[2], **wait_bh = wait;
735         unsigned int block_end, block_start;
736         unsigned int bsize = 1 << inode->i_blkbits;
737
738         if (!page_has_buffers(page))
739                 create_empty_buffers(page, bsize, 0);
740
741         head = page_buffers(page);
742         for (bh = head, block_start = 0; bh != head || !block_start;
743              bh = bh->b_this_page, block_start += bsize) {
744                 block_end = block_start + bsize;
745
746                 clear_buffer_new(bh);
747
748                 /*
749                  * Ignore blocks outside of our i/o range -
750                  * they may belong to unallocated clusters.
751                  */
752                 if (block_start >= to || block_end <= from) {
753                         if (PageUptodate(page))
754                                 set_buffer_uptodate(bh);
755                         continue;
756                 }
757
758                 /*
759                  * For an allocating write with cluster size >= page
760                  * size, we always write the entire page.
761                  */
762                 if (new)
763                         set_buffer_new(bh);
764
765                 if (!buffer_mapped(bh)) {
766                         map_bh(bh, inode->i_sb, *p_blkno);
767                         unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
768                 }
769
770                 if (PageUptodate(page)) {
771                         if (!buffer_uptodate(bh))
772                                 set_buffer_uptodate(bh);
773                 } else if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
774                            !buffer_new(bh) &&
775                            ocfs2_should_read_blk(inode, page, block_start) &&
776                            (block_start < from || block_end > to)) {
777                         ll_rw_block(READ, 1, &bh);
778                         *wait_bh++=bh;
779                 }
780
781                 *p_blkno = *p_blkno + 1;
782         }
783
784         /*
785          * If we issued read requests - let them complete.
786          */
787         while(wait_bh > wait) {
788                 wait_on_buffer(*--wait_bh);
789                 if (!buffer_uptodate(*wait_bh))
790                         ret = -EIO;
791         }
792
793         if (ret == 0 || !new)
794                 return ret;
795
796         /*
797          * If we get -EIO above, zero out any newly allocated blocks
798          * to avoid exposing stale data.
799          */
800         bh = head;
801         block_start = 0;
802         do {
803                 block_end = block_start + bsize;
804                 if (block_end <= from)
805                         goto next_bh;
806                 if (block_start >= to)
807                         break;
808
809                 zero_user(page, block_start, bh->b_size);
810                 set_buffer_uptodate(bh);
811                 mark_buffer_dirty(bh);
812
813 next_bh:
814                 block_start = block_end;
815                 bh = bh->b_this_page;
816         } while (bh != head);
817
818         return ret;
819 }
820
821 #if (PAGE_CACHE_SIZE >= OCFS2_MAX_CLUSTERSIZE)
822 #define OCFS2_MAX_CTXT_PAGES    1
823 #else
824 #define OCFS2_MAX_CTXT_PAGES    (OCFS2_MAX_CLUSTERSIZE / PAGE_CACHE_SIZE)
825 #endif
826
827 #define OCFS2_MAX_CLUSTERS_PER_PAGE     (PAGE_CACHE_SIZE / OCFS2_MIN_CLUSTERSIZE)
828
829 /*
830  * Describe the state of a single cluster to be written to.
831  */
832 struct ocfs2_write_cluster_desc {
833         u32             c_cpos;
834         u32             c_phys;
835         /*
836          * Give this a unique field because c_phys eventually gets
837          * filled.
838          */
839         unsigned        c_new;
840         unsigned        c_unwritten;
841         unsigned        c_needs_zero;
842 };
843
844 struct ocfs2_write_ctxt {
845         /* Logical cluster position / len of write */
846         u32                             w_cpos;
847         u32                             w_clen;
848
849         /* First cluster allocated in a nonsparse extend */
850         u32                             w_first_new_cpos;
851
852         struct ocfs2_write_cluster_desc w_desc[OCFS2_MAX_CLUSTERS_PER_PAGE];
853
854         /*
855          * This is true if page_size > cluster_size.
856          *
857          * It triggers a set of special cases during write which might
858          * have to deal with allocating writes to partial pages.
859          */
860         unsigned int                    w_large_pages;
861
862         /*
863          * Pages involved in this write.
864          *
865          * w_target_page is the page being written to by the user.
866          *
867          * w_pages is an array of pages which always contains
868          * w_target_page, and in the case of an allocating write with
869          * page_size < cluster size, it will contain zero'd and mapped
870          * pages adjacent to w_target_page which need to be written
871          * out in so that future reads from that region will get
872          * zero's.
873          */
874         unsigned int                    w_num_pages;
875         struct page                     *w_pages[OCFS2_MAX_CTXT_PAGES];
876         struct page                     *w_target_page;
877
878         /*
879          * ocfs2_write_end() uses this to know what the real range to
880          * write in the target should be.
881          */
882         unsigned int                    w_target_from;
883         unsigned int                    w_target_to;
884
885         /*
886          * We could use journal_current_handle() but this is cleaner,
887          * IMHO -Mark
888          */
889         handle_t                        *w_handle;
890
891         struct buffer_head              *w_di_bh;
892
893         struct ocfs2_cached_dealloc_ctxt w_dealloc;
894 };
895
896 void ocfs2_unlock_and_free_pages(struct page **pages, int num_pages)
897 {
898         int i;
899
900         for(i = 0; i < num_pages; i++) {
901                 if (pages[i]) {
902                         unlock_page(pages[i]);
903                         mark_page_accessed(pages[i]);
904                         page_cache_release(pages[i]);
905                 }
906         }
907 }
908
909 static void ocfs2_free_write_ctxt(struct ocfs2_write_ctxt *wc)
910 {
911         ocfs2_unlock_and_free_pages(wc->w_pages, wc->w_num_pages);
912
913         brelse(wc->w_di_bh);
914         kfree(wc);
915 }
916
917 static int ocfs2_alloc_write_ctxt(struct ocfs2_write_ctxt **wcp,
918                                   struct ocfs2_super *osb, loff_t pos,
919                                   unsigned len, struct buffer_head *di_bh)
920 {
921         u32 cend;
922         struct ocfs2_write_ctxt *wc;
923
924         wc = kzalloc(sizeof(struct ocfs2_write_ctxt), GFP_NOFS);
925         if (!wc)
926                 return -ENOMEM;
927
928         wc->w_cpos = pos >> osb->s_clustersize_bits;
929         wc->w_first_new_cpos = UINT_MAX;
930         cend = (pos + len - 1) >> osb->s_clustersize_bits;
931         wc->w_clen = cend - wc->w_cpos + 1;
932         get_bh(di_bh);
933         wc->w_di_bh = di_bh;
934
935         if (unlikely(PAGE_CACHE_SHIFT > osb->s_clustersize_bits))
936                 wc->w_large_pages = 1;
937         else
938                 wc->w_large_pages = 0;
939
940         ocfs2_init_dealloc_ctxt(&wc->w_dealloc);
941
942         *wcp = wc;
943
944         return 0;
945 }
946
947 /*
948  * If a page has any new buffers, zero them out here, and mark them uptodate
949  * and dirty so they'll be written out (in order to prevent uninitialised
950  * block data from leaking). And clear the new bit.
951  */
952 static void ocfs2_zero_new_buffers(struct page *page, unsigned from, unsigned to)
953 {
954         unsigned int block_start, block_end;
955         struct buffer_head *head, *bh;
956
957         BUG_ON(!PageLocked(page));
958         if (!page_has_buffers(page))
959                 return;
960
961         bh = head = page_buffers(page);
962         block_start = 0;
963         do {
964                 block_end = block_start + bh->b_size;
965
966                 if (buffer_new(bh)) {
967                         if (block_end > from && block_start < to) {
968                                 if (!PageUptodate(page)) {
969                                         unsigned start, end;
970
971                                         start = max(from, block_start);
972                                         end = min(to, block_end);
973
974                                         zero_user_segment(page, start, end);
975                                         set_buffer_uptodate(bh);
976                                 }
977
978                                 clear_buffer_new(bh);
979                                 mark_buffer_dirty(bh);
980                         }
981                 }
982
983                 block_start = block_end;
984                 bh = bh->b_this_page;
985         } while (bh != head);
986 }
987
988 /*
989  * Only called when we have a failure during allocating write to write
990  * zero's to the newly allocated region.
991  */
992 static void ocfs2_write_failure(struct inode *inode,
993                                 struct ocfs2_write_ctxt *wc,
994                                 loff_t user_pos, unsigned user_len)
995 {
996         int i;
997         unsigned from = user_pos & (PAGE_CACHE_SIZE - 1),
998                 to = user_pos + user_len;
999         struct page *tmppage;
1000
1001         ocfs2_zero_new_buffers(wc->w_target_page, from, to);
1002
1003         for(i = 0; i < wc->w_num_pages; i++) {
1004                 tmppage = wc->w_pages[i];
1005
1006                 if (page_has_buffers(tmppage)) {
1007                         if (ocfs2_should_order_data(inode))
1008                                 ocfs2_jbd2_file_inode(wc->w_handle, inode);
1009
1010                         block_commit_write(tmppage, from, to);
1011                 }
1012         }
1013 }
1014
1015 static int ocfs2_prepare_page_for_write(struct inode *inode, u64 *p_blkno,
1016                                         struct ocfs2_write_ctxt *wc,
1017                                         struct page *page, u32 cpos,
1018                                         loff_t user_pos, unsigned user_len,
1019                                         int new)
1020 {
1021         int ret;
1022         unsigned int map_from = 0, map_to = 0;
1023         unsigned int cluster_start, cluster_end;
1024         unsigned int user_data_from = 0, user_data_to = 0;
1025
1026         ocfs2_figure_cluster_boundaries(OCFS2_SB(inode->i_sb), cpos,
1027                                         &cluster_start, &cluster_end);
1028
1029         if (page == wc->w_target_page) {
1030                 map_from = user_pos & (PAGE_CACHE_SIZE - 1);
1031                 map_to = map_from + user_len;
1032
1033                 if (new)
1034                         ret = ocfs2_map_page_blocks(page, p_blkno, inode,
1035                                                     cluster_start, cluster_end,
1036                                                     new);
1037                 else
1038                         ret = ocfs2_map_page_blocks(page, p_blkno, inode,
1039                                                     map_from, map_to, new);
1040                 if (ret) {
1041                         mlog_errno(ret);
1042                         goto out;
1043                 }
1044
1045                 user_data_from = map_from;
1046                 user_data_to = map_to;
1047                 if (new) {
1048                         map_from = cluster_start;
1049                         map_to = cluster_end;
1050                 }
1051         } else {
1052                 /*
1053                  * If we haven't allocated the new page yet, we
1054                  * shouldn't be writing it out without copying user
1055                  * data. This is likely a math error from the caller.
1056                  */
1057                 BUG_ON(!new);
1058
1059                 map_from = cluster_start;
1060                 map_to = cluster_end;
1061
1062                 ret = ocfs2_map_page_blocks(page, p_blkno, inode,
1063                                             cluster_start, cluster_end, new);
1064                 if (ret) {
1065                         mlog_errno(ret);
1066                         goto out;
1067                 }
1068         }
1069
1070         /*
1071          * Parts of newly allocated pages need to be zero'd.
1072          *
1073          * Above, we have also rewritten 'to' and 'from' - as far as
1074          * the rest of the function is concerned, the entire cluster
1075          * range inside of a page needs to be written.
1076          *
1077          * We can skip this if the page is up to date - it's already
1078          * been zero'd from being read in as a hole.
1079          */
1080         if (new && !PageUptodate(page))
1081                 ocfs2_clear_page_regions(page, OCFS2_SB(inode->i_sb),
1082                                          cpos, user_data_from, user_data_to);
1083
1084         flush_dcache_page(page);
1085
1086 out:
1087         return ret;
1088 }
1089
1090 /*
1091  * This function will only grab one clusters worth of pages.
1092  */
1093 static int ocfs2_grab_pages_for_write(struct address_space *mapping,
1094                                       struct ocfs2_write_ctxt *wc,
1095                                       u32 cpos, loff_t user_pos,
1096                                       unsigned user_len, int new,
1097                                       struct page *mmap_page)
1098 {
1099         int ret = 0, i;
1100         unsigned long start, target_index, end_index, index;
1101         struct inode *inode = mapping->host;
1102         loff_t last_byte;
1103
1104         target_index = user_pos >> PAGE_CACHE_SHIFT;
1105
1106         /*
1107          * Figure out how many pages we'll be manipulating here. For
1108          * non allocating write, we just change the one
1109          * page. Otherwise, we'll need a whole clusters worth.  If we're
1110          * writing past i_size, we only need enough pages to cover the
1111          * last page of the write.
1112          */
1113         if (new) {
1114                 wc->w_num_pages = ocfs2_pages_per_cluster(inode->i_sb);
1115                 start = ocfs2_align_clusters_to_page_index(inode->i_sb, cpos);
1116                 /*
1117                  * We need the index *past* the last page we could possibly
1118                  * touch.  This is the page past the end of the write or
1119                  * i_size, whichever is greater.
1120                  */
1121                 last_byte = max(user_pos + user_len, i_size_read(inode));
1122                 BUG_ON(last_byte < 1);
1123                 end_index = ((last_byte - 1) >> PAGE_CACHE_SHIFT) + 1;
1124                 if ((start + wc->w_num_pages) > end_index)
1125                         wc->w_num_pages = end_index - start;
1126         } else {
1127                 wc->w_num_pages = 1;
1128                 start = target_index;
1129         }
1130
1131         for(i = 0; i < wc->w_num_pages; i++) {
1132                 index = start + i;
1133
1134                 if (index == target_index && mmap_page) {
1135                         /*
1136                          * ocfs2_pagemkwrite() is a little different
1137                          * and wants us to directly use the page
1138                          * passed in.
1139                          */
1140                         lock_page(mmap_page);
1141
1142                         if (mmap_page->mapping != mapping) {
1143                                 unlock_page(mmap_page);
1144                                 /*
1145                                  * Sanity check - the locking in
1146                                  * ocfs2_pagemkwrite() should ensure
1147                                  * that this code doesn't trigger.
1148                                  */
1149                                 ret = -EINVAL;
1150                                 mlog_errno(ret);
1151                                 goto out;
1152                         }
1153
1154                         page_cache_get(mmap_page);
1155                         wc->w_pages[i] = mmap_page;
1156                 } else {
1157                         wc->w_pages[i] = find_or_create_page(mapping, index,
1158                                                              GFP_NOFS);
1159                         if (!wc->w_pages[i]) {
1160                                 ret = -ENOMEM;
1161                                 mlog_errno(ret);
1162                                 goto out;
1163                         }
1164                 }
1165
1166                 if (index == target_index)
1167                         wc->w_target_page = wc->w_pages[i];
1168         }
1169 out:
1170         return ret;
1171 }
1172
1173 /*
1174  * Prepare a single cluster for write one cluster into the file.
1175  */
1176 static int ocfs2_write_cluster(struct address_space *mapping,
1177                                u32 phys, unsigned int unwritten,
1178                                unsigned int should_zero,
1179                                struct ocfs2_alloc_context *data_ac,
1180                                struct ocfs2_alloc_context *meta_ac,
1181                                struct ocfs2_write_ctxt *wc, u32 cpos,
1182                                loff_t user_pos, unsigned user_len)
1183 {
1184         int ret, i, new;
1185         u64 v_blkno, p_blkno;
1186         struct inode *inode = mapping->host;
1187         struct ocfs2_extent_tree et;
1188
1189         new = phys == 0 ? 1 : 0;
1190         if (new) {
1191                 u32 tmp_pos;
1192
1193                 /*
1194                  * This is safe to call with the page locks - it won't take
1195                  * any additional semaphores or cluster locks.
1196                  */
1197                 tmp_pos = cpos;
1198                 ret = ocfs2_add_inode_data(OCFS2_SB(inode->i_sb), inode,
1199                                            &tmp_pos, 1, 0, wc->w_di_bh,
1200                                            wc->w_handle, data_ac,
1201                                            meta_ac, NULL);
1202                 /*
1203                  * This shouldn't happen because we must have already
1204                  * calculated the correct meta data allocation required. The
1205                  * internal tree allocation code should know how to increase
1206                  * transaction credits itself.
1207                  *
1208                  * If need be, we could handle -EAGAIN for a
1209                  * RESTART_TRANS here.
1210                  */
1211                 mlog_bug_on_msg(ret == -EAGAIN,
1212                                 "Inode %llu: EAGAIN return during allocation.\n",
1213                                 (unsigned long long)OCFS2_I(inode)->ip_blkno);
1214                 if (ret < 0) {
1215                         mlog_errno(ret);
1216                         goto out;
1217                 }
1218         } else if (unwritten) {
1219                 ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode),
1220                                               wc->w_di_bh);
1221                 ret = ocfs2_mark_extent_written(inode, &et,
1222                                                 wc->w_handle, cpos, 1, phys,
1223                                                 meta_ac, &wc->w_dealloc);
1224                 if (ret < 0) {
1225                         mlog_errno(ret);
1226                         goto out;
1227                 }
1228         }
1229
1230         if (should_zero)
1231                 v_blkno = ocfs2_clusters_to_blocks(inode->i_sb, cpos);
1232         else
1233                 v_blkno = user_pos >> inode->i_sb->s_blocksize_bits;
1234
1235         /*
1236          * The only reason this should fail is due to an inability to
1237          * find the extent added.
1238          */
1239         ret = ocfs2_extent_map_get_blocks(inode, v_blkno, &p_blkno, NULL,
1240                                           NULL);
1241         if (ret < 0) {
1242                 ocfs2_error(inode->i_sb, "Corrupting extend for inode %llu, "
1243                             "at logical block %llu",
1244                             (unsigned long long)OCFS2_I(inode)->ip_blkno,
1245                             (unsigned long long)v_blkno);
1246                 goto out;
1247         }
1248
1249         BUG_ON(p_blkno == 0);
1250
1251         for(i = 0; i < wc->w_num_pages; i++) {
1252                 int tmpret;
1253
1254                 tmpret = ocfs2_prepare_page_for_write(inode, &p_blkno, wc,
1255                                                       wc->w_pages[i], cpos,
1256                                                       user_pos, user_len,
1257                                                       should_zero);
1258                 if (tmpret) {
1259                         mlog_errno(tmpret);
1260                         if (ret == 0)
1261                                 ret = tmpret;
1262                 }
1263         }
1264
1265         /*
1266          * We only have cleanup to do in case of allocating write.
1267          */
1268         if (ret && new)
1269                 ocfs2_write_failure(inode, wc, user_pos, user_len);
1270
1271 out:
1272
1273         return ret;
1274 }
1275
1276 static int ocfs2_write_cluster_by_desc(struct address_space *mapping,
1277                                        struct ocfs2_alloc_context *data_ac,
1278                                        struct ocfs2_alloc_context *meta_ac,
1279                                        struct ocfs2_write_ctxt *wc,
1280                                        loff_t pos, unsigned len)
1281 {
1282         int ret, i;
1283         loff_t cluster_off;
1284         unsigned int local_len = len;
1285         struct ocfs2_write_cluster_desc *desc;
1286         struct ocfs2_super *osb = OCFS2_SB(mapping->host->i_sb);
1287
1288         for (i = 0; i < wc->w_clen; i++) {
1289                 desc = &wc->w_desc[i];
1290
1291                 /*
1292                  * We have to make sure that the total write passed in
1293                  * doesn't extend past a single cluster.
1294                  */
1295                 local_len = len;
1296                 cluster_off = pos & (osb->s_clustersize - 1);
1297                 if ((cluster_off + local_len) > osb->s_clustersize)
1298                         local_len = osb->s_clustersize - cluster_off;
1299
1300                 ret = ocfs2_write_cluster(mapping, desc->c_phys,
1301                                           desc->c_unwritten,
1302                                           desc->c_needs_zero,
1303                                           data_ac, meta_ac,
1304                                           wc, desc->c_cpos, pos, local_len);
1305                 if (ret) {
1306                         mlog_errno(ret);
1307                         goto out;
1308                 }
1309
1310                 len -= local_len;
1311                 pos += local_len;
1312         }
1313
1314         ret = 0;
1315 out:
1316         return ret;
1317 }
1318
1319 /*
1320  * ocfs2_write_end() wants to know which parts of the target page it
1321  * should complete the write on. It's easiest to compute them ahead of
1322  * time when a more complete view of the write is available.
1323  */
1324 static void ocfs2_set_target_boundaries(struct ocfs2_super *osb,
1325                                         struct ocfs2_write_ctxt *wc,
1326                                         loff_t pos, unsigned len, int alloc)
1327 {
1328         struct ocfs2_write_cluster_desc *desc;
1329
1330         wc->w_target_from = pos & (PAGE_CACHE_SIZE - 1);
1331         wc->w_target_to = wc->w_target_from + len;
1332
1333         if (alloc == 0)
1334                 return;
1335
1336         /*
1337          * Allocating write - we may have different boundaries based
1338          * on page size and cluster size.
1339          *
1340          * NOTE: We can no longer compute one value from the other as
1341          * the actual write length and user provided length may be
1342          * different.
1343          */
1344
1345         if (wc->w_large_pages) {
1346                 /*
1347                  * We only care about the 1st and last cluster within
1348                  * our range and whether they should be zero'd or not. Either
1349                  * value may be extended out to the start/end of a
1350                  * newly allocated cluster.
1351                  */
1352                 desc = &wc->w_desc[0];
1353                 if (desc->c_needs_zero)
1354                         ocfs2_figure_cluster_boundaries(osb,
1355                                                         desc->c_cpos,
1356                                                         &wc->w_target_from,
1357                                                         NULL);
1358
1359                 desc = &wc->w_desc[wc->w_clen - 1];
1360                 if (desc->c_needs_zero)
1361                         ocfs2_figure_cluster_boundaries(osb,
1362                                                         desc->c_cpos,
1363                                                         NULL,
1364                                                         &wc->w_target_to);
1365         } else {
1366                 wc->w_target_from = 0;
1367                 wc->w_target_to = PAGE_CACHE_SIZE;
1368         }
1369 }
1370
1371 /*
1372  * Populate each single-cluster write descriptor in the write context
1373  * with information about the i/o to be done.
1374  *
1375  * Returns the number of clusters that will have to be allocated, as
1376  * well as a worst case estimate of the number of extent records that
1377  * would have to be created during a write to an unwritten region.
1378  */
1379 static int ocfs2_populate_write_desc(struct inode *inode,
1380                                      struct ocfs2_write_ctxt *wc,
1381                                      unsigned int *clusters_to_alloc,
1382                                      unsigned int *extents_to_split)
1383 {
1384         int ret;
1385         struct ocfs2_write_cluster_desc *desc;
1386         unsigned int num_clusters = 0;
1387         unsigned int ext_flags = 0;
1388         u32 phys = 0;
1389         int i;
1390
1391         *clusters_to_alloc = 0;
1392         *extents_to_split = 0;
1393
1394         for (i = 0; i < wc->w_clen; i++) {
1395                 desc = &wc->w_desc[i];
1396                 desc->c_cpos = wc->w_cpos + i;
1397
1398                 if (num_clusters == 0) {
1399                         /*
1400                          * Need to look up the next extent record.
1401                          */
1402                         ret = ocfs2_get_clusters(inode, desc->c_cpos, &phys,
1403                                                  &num_clusters, &ext_flags);
1404                         if (ret) {
1405                                 mlog_errno(ret);
1406                                 goto out;
1407                         }
1408
1409                         /* We should already CoW the refcountd extent. */
1410                         BUG_ON(ext_flags & OCFS2_EXT_REFCOUNTED);
1411
1412                         /*
1413                          * Assume worst case - that we're writing in
1414                          * the middle of the extent.
1415                          *
1416                          * We can assume that the write proceeds from
1417                          * left to right, in which case the extent
1418                          * insert code is smart enough to coalesce the
1419                          * next splits into the previous records created.
1420                          */
1421                         if (ext_flags & OCFS2_EXT_UNWRITTEN)
1422                                 *extents_to_split = *extents_to_split + 2;
1423                 } else if (phys) {
1424                         /*
1425                          * Only increment phys if it doesn't describe
1426                          * a hole.
1427                          */
1428                         phys++;
1429                 }
1430
1431                 /*
1432                  * If w_first_new_cpos is < UINT_MAX, we have a non-sparse
1433                  * file that got extended.  w_first_new_cpos tells us
1434                  * where the newly allocated clusters are so we can
1435                  * zero them.
1436                  */
1437                 if (desc->c_cpos >= wc->w_first_new_cpos) {
1438                         BUG_ON(phys == 0);
1439                         desc->c_needs_zero = 1;
1440                 }
1441
1442                 desc->c_phys = phys;
1443                 if (phys == 0) {
1444                         desc->c_new = 1;
1445                         desc->c_needs_zero = 1;
1446                         *clusters_to_alloc = *clusters_to_alloc + 1;
1447                 }
1448
1449                 if (ext_flags & OCFS2_EXT_UNWRITTEN) {
1450                         desc->c_unwritten = 1;
1451                         desc->c_needs_zero = 1;
1452                 }
1453
1454                 num_clusters--;
1455         }
1456
1457         ret = 0;
1458 out:
1459         return ret;
1460 }
1461
1462 static int ocfs2_write_begin_inline(struct address_space *mapping,
1463                                     struct inode *inode,
1464                                     struct ocfs2_write_ctxt *wc)
1465 {
1466         int ret;
1467         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
1468         struct page *page;
1469         handle_t *handle;
1470         struct ocfs2_dinode *di = (struct ocfs2_dinode *)wc->w_di_bh->b_data;
1471
1472         page = find_or_create_page(mapping, 0, GFP_NOFS);
1473         if (!page) {
1474                 ret = -ENOMEM;
1475                 mlog_errno(ret);
1476                 goto out;
1477         }
1478         /*
1479          * If we don't set w_num_pages then this page won't get unlocked
1480          * and freed on cleanup of the write context.
1481          */
1482         wc->w_pages[0] = wc->w_target_page = page;
1483         wc->w_num_pages = 1;
1484
1485         handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
1486         if (IS_ERR(handle)) {
1487                 ret = PTR_ERR(handle);
1488                 mlog_errno(ret);
1489                 goto out;
1490         }
1491
1492         ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), wc->w_di_bh,
1493                                       OCFS2_JOURNAL_ACCESS_WRITE);
1494         if (ret) {
1495                 ocfs2_commit_trans(osb, handle);
1496
1497                 mlog_errno(ret);
1498                 goto out;
1499         }
1500
1501         if (!(OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL))
1502                 ocfs2_set_inode_data_inline(inode, di);
1503
1504         if (!PageUptodate(page)) {
1505                 ret = ocfs2_read_inline_data(inode, page, wc->w_di_bh);
1506                 if (ret) {
1507                         ocfs2_commit_trans(osb, handle);
1508
1509                         goto out;
1510                 }
1511         }
1512
1513         wc->w_handle = handle;
1514 out:
1515         return ret;
1516 }
1517
1518 int ocfs2_size_fits_inline_data(struct buffer_head *di_bh, u64 new_size)
1519 {
1520         struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
1521
1522         if (new_size <= le16_to_cpu(di->id2.i_data.id_count))
1523                 return 1;
1524         return 0;
1525 }
1526
1527 static int ocfs2_try_to_write_inline_data(struct address_space *mapping,
1528                                           struct inode *inode, loff_t pos,
1529                                           unsigned len, struct page *mmap_page,
1530                                           struct ocfs2_write_ctxt *wc)
1531 {
1532         int ret, written = 0;
1533         loff_t end = pos + len;
1534         struct ocfs2_inode_info *oi = OCFS2_I(inode);
1535         struct ocfs2_dinode *di = NULL;
1536
1537         mlog(0, "Inode %llu, write of %u bytes at off %llu. features: 0x%x\n",
1538              (unsigned long long)oi->ip_blkno, len, (unsigned long long)pos,
1539              oi->ip_dyn_features);
1540
1541         /*
1542          * Handle inodes which already have inline data 1st.
1543          */
1544         if (oi->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
1545                 if (mmap_page == NULL &&
1546                     ocfs2_size_fits_inline_data(wc->w_di_bh, end))
1547                         goto do_inline_write;
1548
1549                 /*
1550                  * The write won't fit - we have to give this inode an
1551                  * inline extent list now.
1552                  */
1553                 ret = ocfs2_convert_inline_data_to_extents(inode, wc->w_di_bh);
1554                 if (ret)
1555                         mlog_errno(ret);
1556                 goto out;
1557         }
1558
1559         /*
1560          * Check whether the inode can accept inline data.
1561          */
1562         if (oi->ip_clusters != 0 || i_size_read(inode) != 0)
1563                 return 0;
1564
1565         /*
1566          * Check whether the write can fit.
1567          */
1568         di = (struct ocfs2_dinode *)wc->w_di_bh->b_data;
1569         if (mmap_page ||
1570             end > ocfs2_max_inline_data_with_xattr(inode->i_sb, di))
1571                 return 0;
1572
1573 do_inline_write:
1574         ret = ocfs2_write_begin_inline(mapping, inode, wc);
1575         if (ret) {
1576                 mlog_errno(ret);
1577                 goto out;
1578         }
1579
1580         /*
1581          * This signals to the caller that the data can be written
1582          * inline.
1583          */
1584         written = 1;
1585 out:
1586         return written ? written : ret;
1587 }
1588
1589 /*
1590  * This function only does anything for file systems which can't
1591  * handle sparse files.
1592  *
1593  * What we want to do here is fill in any hole between the current end
1594  * of allocation and the end of our write. That way the rest of the
1595  * write path can treat it as an non-allocating write, which has no
1596  * special case code for sparse/nonsparse files.
1597  */
1598 static int ocfs2_expand_nonsparse_inode(struct inode *inode,
1599                                         struct buffer_head *di_bh,
1600                                         loff_t pos, unsigned len,
1601                                         struct ocfs2_write_ctxt *wc)
1602 {
1603         int ret;
1604         loff_t newsize = pos + len;
1605
1606         BUG_ON(ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)));
1607
1608         if (newsize <= i_size_read(inode))
1609                 return 0;
1610
1611         ret = ocfs2_extend_no_holes(inode, di_bh, newsize, pos);
1612         if (ret)
1613                 mlog_errno(ret);
1614
1615         wc->w_first_new_cpos =
1616                 ocfs2_clusters_for_bytes(inode->i_sb, i_size_read(inode));
1617
1618         return ret;
1619 }
1620
1621 static int ocfs2_zero_tail(struct inode *inode, struct buffer_head *di_bh,
1622                            loff_t pos)
1623 {
1624         int ret = 0;
1625
1626         BUG_ON(!ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)));
1627         if (pos > i_size_read(inode))
1628                 ret = ocfs2_zero_extend(inode, di_bh, pos);
1629
1630         return ret;
1631 }
1632
1633 /*
1634  * Try to flush truncate logs if we can free enough clusters from it.
1635  * As for return value, "< 0" means error, "0" no space and "1" means
1636  * we have freed enough spaces and let the caller try to allocate again.
1637  */
1638 static int ocfs2_try_to_free_truncate_log(struct ocfs2_super *osb,
1639                                           unsigned int needed)
1640 {
1641         tid_t target;
1642         int ret = 0;
1643         unsigned int truncated_clusters;
1644
1645         mutex_lock(&osb->osb_tl_inode->i_mutex);
1646         truncated_clusters = osb->truncated_clusters;
1647         mutex_unlock(&osb->osb_tl_inode->i_mutex);
1648
1649         /*
1650          * Check whether we can succeed in allocating if we free
1651          * the truncate log.
1652          */
1653         if (truncated_clusters < needed)
1654                 goto out;
1655
1656         ret = ocfs2_flush_truncate_log(osb);
1657         if (ret) {
1658                 mlog_errno(ret);
1659                 goto out;
1660         }
1661
1662         if (jbd2_journal_start_commit(osb->journal->j_journal, &target)) {
1663                 jbd2_log_wait_commit(osb->journal->j_journal, target);
1664                 ret = 1;
1665         }
1666 out:
1667         return ret;
1668 }
1669
1670 int ocfs2_write_begin_nolock(struct file *filp,
1671                              struct address_space *mapping,
1672                              loff_t pos, unsigned len, unsigned flags,
1673                              struct page **pagep, void **fsdata,
1674                              struct buffer_head *di_bh, struct page *mmap_page)
1675 {
1676         int ret, cluster_of_pages, credits = OCFS2_INODE_UPDATE_CREDITS;
1677         unsigned int clusters_to_alloc, extents_to_split, clusters_need = 0;
1678         struct ocfs2_write_ctxt *wc;
1679         struct inode *inode = mapping->host;
1680         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
1681         struct ocfs2_dinode *di;
1682         struct ocfs2_alloc_context *data_ac = NULL;
1683         struct ocfs2_alloc_context *meta_ac = NULL;
1684         handle_t *handle;
1685         struct ocfs2_extent_tree et;
1686         int try_free = 1, ret1;
1687
1688 try_again:
1689         ret = ocfs2_alloc_write_ctxt(&wc, osb, pos, len, di_bh);
1690         if (ret) {
1691                 mlog_errno(ret);
1692                 return ret;
1693         }
1694
1695         if (ocfs2_supports_inline_data(osb)) {
1696                 ret = ocfs2_try_to_write_inline_data(mapping, inode, pos, len,
1697                                                      mmap_page, wc);
1698                 if (ret == 1) {
1699                         ret = 0;
1700                         goto success;
1701                 }
1702                 if (ret < 0) {
1703                         mlog_errno(ret);
1704                         goto out;
1705                 }
1706         }
1707
1708         if (ocfs2_sparse_alloc(osb))
1709                 ret = ocfs2_zero_tail(inode, di_bh, pos);
1710         else
1711                 ret = ocfs2_expand_nonsparse_inode(inode, di_bh, pos, len,
1712                                                    wc);
1713         if (ret) {
1714                 mlog_errno(ret);
1715                 goto out;
1716         }
1717
1718         ret = ocfs2_check_range_for_refcount(inode, pos, len);
1719         if (ret < 0) {
1720                 mlog_errno(ret);
1721                 goto out;
1722         } else if (ret == 1) {
1723                 clusters_need = wc->w_clen;
1724                 ret = ocfs2_refcount_cow(inode, filp, di_bh,
1725                                          wc->w_cpos, wc->w_clen, UINT_MAX);
1726                 if (ret) {
1727                         mlog_errno(ret);
1728                         goto out;
1729                 }
1730         }
1731
1732         ret = ocfs2_populate_write_desc(inode, wc, &clusters_to_alloc,
1733                                         &extents_to_split);
1734         if (ret) {
1735                 mlog_errno(ret);
1736                 goto out;
1737         }
1738         clusters_need += clusters_to_alloc;
1739
1740         di = (struct ocfs2_dinode *)wc->w_di_bh->b_data;
1741
1742         /*
1743          * We set w_target_from, w_target_to here so that
1744          * ocfs2_write_end() knows which range in the target page to
1745          * write out. An allocation requires that we write the entire
1746          * cluster range.
1747          */
1748         if (clusters_to_alloc || extents_to_split) {
1749                 /*
1750                  * XXX: We are stretching the limits of
1751                  * ocfs2_lock_allocators(). It greatly over-estimates
1752                  * the work to be done.
1753                  */
1754                 mlog(0, "extend inode %llu, i_size = %lld, di->i_clusters = %u,"
1755                      " clusters_to_add = %u, extents_to_split = %u\n",
1756                      (unsigned long long)OCFS2_I(inode)->ip_blkno,
1757                      (long long)i_size_read(inode), le32_to_cpu(di->i_clusters),
1758                      clusters_to_alloc, extents_to_split);
1759
1760                 ocfs2_init_dinode_extent_tree(&et, INODE_CACHE(inode),
1761                                               wc->w_di_bh);
1762                 ret = ocfs2_lock_allocators(inode, &et,
1763                                             clusters_to_alloc, extents_to_split,
1764                                             &data_ac, &meta_ac);
1765                 if (ret) {
1766                         mlog_errno(ret);
1767                         goto out;
1768                 }
1769
1770                 if (data_ac)
1771                         data_ac->ac_resv = &OCFS2_I(inode)->ip_la_data_resv;
1772
1773                 credits = ocfs2_calc_extend_credits(inode->i_sb,
1774                                                     &di->id2.i_list,
1775                                                     clusters_to_alloc);
1776
1777         }
1778
1779         /*
1780          * We have to zero sparse allocated clusters, unwritten extent clusters,
1781          * and non-sparse clusters we just extended.  For non-sparse writes,
1782          * we know zeros will only be needed in the first and/or last cluster.
1783          */
1784         if (clusters_to_alloc || extents_to_split ||
1785             (wc->w_clen && (wc->w_desc[0].c_needs_zero ||
1786                             wc->w_desc[wc->w_clen - 1].c_needs_zero)))
1787                 cluster_of_pages = 1;
1788         else
1789                 cluster_of_pages = 0;
1790
1791         ocfs2_set_target_boundaries(osb, wc, pos, len, cluster_of_pages);
1792
1793         handle = ocfs2_start_trans(osb, credits);
1794         if (IS_ERR(handle)) {
1795                 ret = PTR_ERR(handle);
1796                 mlog_errno(ret);
1797                 goto out;
1798         }
1799
1800         wc->w_handle = handle;
1801
1802         if (clusters_to_alloc) {
1803                 ret = dquot_alloc_space_nodirty(inode,
1804                         ocfs2_clusters_to_bytes(osb->sb, clusters_to_alloc));
1805                 if (ret)
1806                         goto out_commit;
1807         }
1808         /*
1809          * We don't want this to fail in ocfs2_write_end(), so do it
1810          * here.
1811          */
1812         ret = ocfs2_journal_access_di(handle, INODE_CACHE(inode), wc->w_di_bh,
1813                                       OCFS2_JOURNAL_ACCESS_WRITE);
1814         if (ret) {
1815                 mlog_errno(ret);
1816                 goto out_quota;
1817         }
1818
1819         /*
1820          * Fill our page array first. That way we've grabbed enough so
1821          * that we can zero and flush if we error after adding the
1822          * extent.
1823          */
1824         ret = ocfs2_grab_pages_for_write(mapping, wc, wc->w_cpos, pos, len,
1825                                          cluster_of_pages, mmap_page);
1826         if (ret) {
1827                 mlog_errno(ret);
1828                 goto out_quota;
1829         }
1830
1831         ret = ocfs2_write_cluster_by_desc(mapping, data_ac, meta_ac, wc, pos,
1832                                           len);
1833         if (ret) {
1834                 mlog_errno(ret);
1835                 goto out_quota;
1836         }
1837
1838         if (data_ac)
1839                 ocfs2_free_alloc_context(data_ac);
1840         if (meta_ac)
1841                 ocfs2_free_alloc_context(meta_ac);
1842
1843 success:
1844         *pagep = wc->w_target_page;
1845         *fsdata = wc;
1846         return 0;
1847 out_quota:
1848         if (clusters_to_alloc)
1849                 dquot_free_space(inode,
1850                           ocfs2_clusters_to_bytes(osb->sb, clusters_to_alloc));
1851 out_commit:
1852         ocfs2_commit_trans(osb, handle);
1853
1854 out:
1855         ocfs2_free_write_ctxt(wc);
1856
1857         if (data_ac)
1858                 ocfs2_free_alloc_context(data_ac);
1859         if (meta_ac)
1860                 ocfs2_free_alloc_context(meta_ac);
1861
1862         if (ret == -ENOSPC && try_free) {
1863                 /*
1864                  * Try to free some truncate log so that we can have enough
1865                  * clusters to allocate.
1866                  */
1867                 try_free = 0;
1868
1869                 ret1 = ocfs2_try_to_free_truncate_log(osb, clusters_need);
1870                 if (ret1 == 1)
1871                         goto try_again;
1872
1873                 if (ret1 < 0)
1874                         mlog_errno(ret1);
1875         }
1876
1877         return ret;
1878 }
1879
1880 static int ocfs2_write_begin(struct file *file, struct address_space *mapping,
1881                              loff_t pos, unsigned len, unsigned flags,
1882                              struct page **pagep, void **fsdata)
1883 {
1884         int ret;
1885         struct buffer_head *di_bh = NULL;
1886         struct inode *inode = mapping->host;
1887
1888         ret = ocfs2_inode_lock(inode, &di_bh, 1);
1889         if (ret) {
1890                 mlog_errno(ret);
1891                 return ret;
1892         }
1893
1894         /*
1895          * Take alloc sem here to prevent concurrent lookups. That way
1896          * the mapping, zeroing and tree manipulation within
1897          * ocfs2_write() will be safe against ->readpage(). This
1898          * should also serve to lock out allocation from a shared
1899          * writeable region.
1900          */
1901         down_write(&OCFS2_I(inode)->ip_alloc_sem);
1902
1903         ret = ocfs2_write_begin_nolock(file, mapping, pos, len, flags, pagep,
1904                                        fsdata, di_bh, NULL);
1905         if (ret) {
1906                 mlog_errno(ret);
1907                 goto out_fail;
1908         }
1909
1910         brelse(di_bh);
1911
1912         return 0;
1913
1914 out_fail:
1915         up_write(&OCFS2_I(inode)->ip_alloc_sem);
1916
1917         brelse(di_bh);
1918         ocfs2_inode_unlock(inode, 1);
1919
1920         return ret;
1921 }
1922
1923 static void ocfs2_write_end_inline(struct inode *inode, loff_t pos,
1924                                    unsigned len, unsigned *copied,
1925                                    struct ocfs2_dinode *di,
1926                                    struct ocfs2_write_ctxt *wc)
1927 {
1928         void *kaddr;
1929
1930         if (unlikely(*copied < len)) {
1931                 if (!PageUptodate(wc->w_target_page)) {
1932                         *copied = 0;
1933                         return;
1934                 }
1935         }
1936
1937         kaddr = kmap_atomic(wc->w_target_page, KM_USER0);
1938         memcpy(di->id2.i_data.id_data + pos, kaddr + pos, *copied);
1939         kunmap_atomic(kaddr, KM_USER0);
1940
1941         mlog(0, "Data written to inode at offset %llu. "
1942              "id_count = %u, copied = %u, i_dyn_features = 0x%x\n",
1943              (unsigned long long)pos, *copied,
1944              le16_to_cpu(di->id2.i_data.id_count),
1945              le16_to_cpu(di->i_dyn_features));
1946 }
1947
1948 int ocfs2_write_end_nolock(struct address_space *mapping,
1949                            loff_t pos, unsigned len, unsigned copied,
1950                            struct page *page, void *fsdata)
1951 {
1952         int i;
1953         unsigned from, to, start = pos & (PAGE_CACHE_SIZE - 1);
1954         struct inode *inode = mapping->host;
1955         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
1956         struct ocfs2_write_ctxt *wc = fsdata;
1957         struct ocfs2_dinode *di = (struct ocfs2_dinode *)wc->w_di_bh->b_data;
1958         handle_t *handle = wc->w_handle;
1959         struct page *tmppage;
1960
1961         if (OCFS2_I(inode)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
1962                 ocfs2_write_end_inline(inode, pos, len, &copied, di, wc);
1963                 goto out_write_size;
1964         }
1965
1966         if (unlikely(copied < len)) {
1967                 if (!PageUptodate(wc->w_target_page))
1968                         copied = 0;
1969
1970                 ocfs2_zero_new_buffers(wc->w_target_page, start+copied,
1971                                        start+len);
1972         }
1973         flush_dcache_page(wc->w_target_page);
1974
1975         for(i = 0; i < wc->w_num_pages; i++) {
1976                 tmppage = wc->w_pages[i];
1977
1978                 if (tmppage == wc->w_target_page) {
1979                         from = wc->w_target_from;
1980                         to = wc->w_target_to;
1981
1982                         BUG_ON(from > PAGE_CACHE_SIZE ||
1983                                to > PAGE_CACHE_SIZE ||
1984                                to < from);
1985                 } else {
1986                         /*
1987                          * Pages adjacent to the target (if any) imply
1988                          * a hole-filling write in which case we want
1989                          * to flush their entire range.
1990                          */
1991                         from = 0;
1992                         to = PAGE_CACHE_SIZE;
1993                 }
1994
1995                 if (page_has_buffers(tmppage)) {
1996                         if (ocfs2_should_order_data(inode))
1997                                 ocfs2_jbd2_file_inode(wc->w_handle, inode);
1998                         block_commit_write(tmppage, from, to);
1999                 }
2000         }
2001
2002 out_write_size:
2003         pos += copied;
2004         if (pos > inode->i_size) {
2005                 i_size_write(inode, pos);
2006                 mark_inode_dirty(inode);
2007         }
2008         inode->i_blocks = ocfs2_inode_sector_count(inode);
2009         di->i_size = cpu_to_le64((u64)i_size_read(inode));
2010         inode->i_mtime = inode->i_ctime = CURRENT_TIME;
2011         di->i_mtime = di->i_ctime = cpu_to_le64(inode->i_mtime.tv_sec);
2012         di->i_mtime_nsec = di->i_ctime_nsec = cpu_to_le32(inode->i_mtime.tv_nsec);
2013         ocfs2_journal_dirty(handle, wc->w_di_bh);
2014
2015         ocfs2_commit_trans(osb, handle);
2016
2017         ocfs2_run_deallocs(osb, &wc->w_dealloc);
2018
2019         ocfs2_free_write_ctxt(wc);
2020
2021         return copied;
2022 }
2023
2024 static int ocfs2_write_end(struct file *file, struct address_space *mapping,
2025                            loff_t pos, unsigned len, unsigned copied,
2026                            struct page *page, void *fsdata)
2027 {
2028         int ret;
2029         struct inode *inode = mapping->host;
2030
2031         ret = ocfs2_write_end_nolock(mapping, pos, len, copied, page, fsdata);
2032
2033         up_write(&OCFS2_I(inode)->ip_alloc_sem);
2034         ocfs2_inode_unlock(inode, 1);
2035
2036         return ret;
2037 }
2038
2039 const struct address_space_operations ocfs2_aops = {
2040         .readpage               = ocfs2_readpage,
2041         .readpages              = ocfs2_readpages,
2042         .writepage              = ocfs2_writepage,
2043         .write_begin            = ocfs2_write_begin,
2044         .write_end              = ocfs2_write_end,
2045         .bmap                   = ocfs2_bmap,
2046         .direct_IO              = ocfs2_direct_IO,
2047         .invalidatepage         = ocfs2_invalidatepage,
2048         .releasepage            = ocfs2_releasepage,
2049         .migratepage            = buffer_migrate_page,
2050         .is_partially_uptodate  = block_is_partially_uptodate,
2051         .error_remove_page      = generic_error_remove_page,
2052 };