aops.c revision 54cb8821de07f2ffcd28c380ce9b93d5784b40d7
1/* -*- mode: c; c-basic-offset: 8; -*-
2 * vim: noexpandtab sw=8 ts=8 sts=0:
3 *
4 * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 * General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public
17 * License along with this program; if not, write to the
18 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19 * Boston, MA 021110-1307, USA.
20 */
21
22#include <linux/fs.h>
23#include <linux/slab.h>
24#include <linux/highmem.h>
25#include <linux/pagemap.h>
26#include <asm/byteorder.h>
27#include <linux/swap.h>
28#include <linux/pipe_fs_i.h>
29
30#define MLOG_MASK_PREFIX ML_FILE_IO
31#include <cluster/masklog.h>
32
33#include "ocfs2.h"
34
35#include "alloc.h"
36#include "aops.h"
37#include "dlmglue.h"
38#include "extent_map.h"
39#include "file.h"
40#include "inode.h"
41#include "journal.h"
42#include "suballoc.h"
43#include "super.h"
44#include "symlink.h"
45
46#include "buffer_head_io.h"
47
48static int ocfs2_symlink_get_block(struct inode *inode, sector_t iblock,
49				   struct buffer_head *bh_result, int create)
50{
51	int err = -EIO;
52	int status;
53	struct ocfs2_dinode *fe = NULL;
54	struct buffer_head *bh = NULL;
55	struct buffer_head *buffer_cache_bh = NULL;
56	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
57	void *kaddr;
58
59	mlog_entry("(0x%p, %llu, 0x%p, %d)\n", inode,
60		   (unsigned long long)iblock, bh_result, create);
61
62	BUG_ON(ocfs2_inode_is_fast_symlink(inode));
63
64	if ((iblock << inode->i_sb->s_blocksize_bits) > PATH_MAX + 1) {
65		mlog(ML_ERROR, "block offset > PATH_MAX: %llu",
66		     (unsigned long long)iblock);
67		goto bail;
68	}
69
70	status = ocfs2_read_block(OCFS2_SB(inode->i_sb),
71				  OCFS2_I(inode)->ip_blkno,
72				  &bh, OCFS2_BH_CACHED, inode);
73	if (status < 0) {
74		mlog_errno(status);
75		goto bail;
76	}
77	fe = (struct ocfs2_dinode *) bh->b_data;
78
79	if (!OCFS2_IS_VALID_DINODE(fe)) {
80		mlog(ML_ERROR, "Invalid dinode #%llu: signature = %.*s\n",
81		     (unsigned long long)le64_to_cpu(fe->i_blkno), 7,
82		     fe->i_signature);
83		goto bail;
84	}
85
86	if ((u64)iblock >= ocfs2_clusters_to_blocks(inode->i_sb,
87						    le32_to_cpu(fe->i_clusters))) {
88		mlog(ML_ERROR, "block offset is outside the allocated size: "
89		     "%llu\n", (unsigned long long)iblock);
90		goto bail;
91	}
92
93	/* We don't use the page cache to create symlink data, so if
94	 * need be, copy it over from the buffer cache. */
95	if (!buffer_uptodate(bh_result) && ocfs2_inode_is_new(inode)) {
96		u64 blkno = le64_to_cpu(fe->id2.i_list.l_recs[0].e_blkno) +
97			    iblock;
98		buffer_cache_bh = sb_getblk(osb->sb, blkno);
99		if (!buffer_cache_bh) {
100			mlog(ML_ERROR, "couldn't getblock for symlink!\n");
101			goto bail;
102		}
103
104		/* we haven't locked out transactions, so a commit
105		 * could've happened. Since we've got a reference on
106		 * the bh, even if it commits while we're doing the
107		 * copy, the data is still good. */
108		if (buffer_jbd(buffer_cache_bh)
109		    && ocfs2_inode_is_new(inode)) {
110			kaddr = kmap_atomic(bh_result->b_page, KM_USER0);
111			if (!kaddr) {
112				mlog(ML_ERROR, "couldn't kmap!\n");
113				goto bail;
114			}
115			memcpy(kaddr + (bh_result->b_size * iblock),
116			       buffer_cache_bh->b_data,
117			       bh_result->b_size);
118			kunmap_atomic(kaddr, KM_USER0);
119			set_buffer_uptodate(bh_result);
120		}
121		brelse(buffer_cache_bh);
122	}
123
124	map_bh(bh_result, inode->i_sb,
125	       le64_to_cpu(fe->id2.i_list.l_recs[0].e_blkno) + iblock);
126
127	err = 0;
128
129bail:
130	if (bh)
131		brelse(bh);
132
133	mlog_exit(err);
134	return err;
135}
136
137static int ocfs2_get_block(struct inode *inode, sector_t iblock,
138			   struct buffer_head *bh_result, int create)
139{
140	int err = 0;
141	unsigned int ext_flags;
142	u64 p_blkno, past_eof;
143	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
144
145	mlog_entry("(0x%p, %llu, 0x%p, %d)\n", inode,
146		   (unsigned long long)iblock, bh_result, create);
147
148	if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_SYSTEM_FILE)
149		mlog(ML_NOTICE, "get_block on system inode 0x%p (%lu)\n",
150		     inode, inode->i_ino);
151
152	if (S_ISLNK(inode->i_mode)) {
153		/* this always does I/O for some reason. */
154		err = ocfs2_symlink_get_block(inode, iblock, bh_result, create);
155		goto bail;
156	}
157
158	err = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno, NULL,
159					  &ext_flags);
160	if (err) {
161		mlog(ML_ERROR, "Error %d from get_blocks(0x%p, %llu, 1, "
162		     "%llu, NULL)\n", err, inode, (unsigned long long)iblock,
163		     (unsigned long long)p_blkno);
164		goto bail;
165	}
166
167	/*
168	 * ocfs2 never allocates in this function - the only time we
169	 * need to use BH_New is when we're extending i_size on a file
170	 * system which doesn't support holes, in which case BH_New
171	 * allows block_prepare_write() to zero.
172	 */
173	mlog_bug_on_msg(create && p_blkno == 0 && ocfs2_sparse_alloc(osb),
174			"ino %lu, iblock %llu\n", inode->i_ino,
175			(unsigned long long)iblock);
176
177	/* Treat the unwritten extent as a hole for zeroing purposes. */
178	if (p_blkno && !(ext_flags & OCFS2_EXT_UNWRITTEN))
179		map_bh(bh_result, inode->i_sb, p_blkno);
180
181	if (!ocfs2_sparse_alloc(osb)) {
182		if (p_blkno == 0) {
183			err = -EIO;
184			mlog(ML_ERROR,
185			     "iblock = %llu p_blkno = %llu blkno=(%llu)\n",
186			     (unsigned long long)iblock,
187			     (unsigned long long)p_blkno,
188			     (unsigned long long)OCFS2_I(inode)->ip_blkno);
189			mlog(ML_ERROR, "Size %llu, clusters %u\n", (unsigned long long)i_size_read(inode), OCFS2_I(inode)->ip_clusters);
190			dump_stack();
191		}
192
193		past_eof = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));
194		mlog(0, "Inode %lu, past_eof = %llu\n", inode->i_ino,
195		     (unsigned long long)past_eof);
196
197		if (create && (iblock >= past_eof))
198			set_buffer_new(bh_result);
199	}
200
201bail:
202	if (err < 0)
203		err = -EIO;
204
205	mlog_exit(err);
206	return err;
207}
208
209static int ocfs2_readpage(struct file *file, struct page *page)
210{
211	struct inode *inode = page->mapping->host;
212	loff_t start = (loff_t)page->index << PAGE_CACHE_SHIFT;
213	int ret, unlock = 1;
214
215	mlog_entry("(0x%p, %lu)\n", file, (page ? page->index : 0));
216
217	ret = ocfs2_meta_lock_with_page(inode, NULL, 0, page);
218	if (ret != 0) {
219		if (ret == AOP_TRUNCATED_PAGE)
220			unlock = 0;
221		mlog_errno(ret);
222		goto out;
223	}
224
225	if (down_read_trylock(&OCFS2_I(inode)->ip_alloc_sem) == 0) {
226		ret = AOP_TRUNCATED_PAGE;
227		goto out_meta_unlock;
228	}
229
230	/*
231	 * i_size might have just been updated as we grabed the meta lock.  We
232	 * might now be discovering a truncate that hit on another node.
233	 * block_read_full_page->get_block freaks out if it is asked to read
234	 * beyond the end of a file, so we check here.  Callers
235	 * (generic_file_read, vm_ops->fault) are clever enough to check i_size
236	 * and notice that the page they just read isn't needed.
237	 *
238	 * XXX sys_readahead() seems to get that wrong?
239	 */
240	if (start >= i_size_read(inode)) {
241		zero_user_page(page, 0, PAGE_SIZE, KM_USER0);
242		SetPageUptodate(page);
243		ret = 0;
244		goto out_alloc;
245	}
246
247	ret = ocfs2_data_lock_with_page(inode, 0, page);
248	if (ret != 0) {
249		if (ret == AOP_TRUNCATED_PAGE)
250			unlock = 0;
251		mlog_errno(ret);
252		goto out_alloc;
253	}
254
255	ret = block_read_full_page(page, ocfs2_get_block);
256	unlock = 0;
257
258	ocfs2_data_unlock(inode, 0);
259out_alloc:
260	up_read(&OCFS2_I(inode)->ip_alloc_sem);
261out_meta_unlock:
262	ocfs2_meta_unlock(inode, 0);
263out:
264	if (unlock)
265		unlock_page(page);
266	mlog_exit(ret);
267	return ret;
268}
269
270/* Note: Because we don't support holes, our allocation has
271 * already happened (allocation writes zeros to the file data)
272 * so we don't have to worry about ordered writes in
273 * ocfs2_writepage.
274 *
275 * ->writepage is called during the process of invalidating the page cache
276 * during blocked lock processing.  It can't block on any cluster locks
277 * to during block mapping.  It's relying on the fact that the block
278 * mapping can't have disappeared under the dirty pages that it is
279 * being asked to write back.
280 */
281static int ocfs2_writepage(struct page *page, struct writeback_control *wbc)
282{
283	int ret;
284
285	mlog_entry("(0x%p)\n", page);
286
287	ret = block_write_full_page(page, ocfs2_get_block, wbc);
288
289	mlog_exit(ret);
290
291	return ret;
292}
293
294/*
295 * This is called from ocfs2_write_zero_page() which has handled it's
296 * own cluster locking and has ensured allocation exists for those
297 * blocks to be written.
298 */
299int ocfs2_prepare_write_nolock(struct inode *inode, struct page *page,
300			       unsigned from, unsigned to)
301{
302	int ret;
303
304	down_read(&OCFS2_I(inode)->ip_alloc_sem);
305
306	ret = block_prepare_write(page, from, to, ocfs2_get_block);
307
308	up_read(&OCFS2_I(inode)->ip_alloc_sem);
309
310	return ret;
311}
312
313/* Taken from ext3. We don't necessarily need the full blown
314 * functionality yet, but IMHO it's better to cut and paste the whole
315 * thing so we can avoid introducing our own bugs (and easily pick up
316 * their fixes when they happen) --Mark */
317int walk_page_buffers(	handle_t *handle,
318			struct buffer_head *head,
319			unsigned from,
320			unsigned to,
321			int *partial,
322			int (*fn)(	handle_t *handle,
323					struct buffer_head *bh))
324{
325	struct buffer_head *bh;
326	unsigned block_start, block_end;
327	unsigned blocksize = head->b_size;
328	int err, ret = 0;
329	struct buffer_head *next;
330
331	for (	bh = head, block_start = 0;
332		ret == 0 && (bh != head || !block_start);
333	    	block_start = block_end, bh = next)
334	{
335		next = bh->b_this_page;
336		block_end = block_start + blocksize;
337		if (block_end <= from || block_start >= to) {
338			if (partial && !buffer_uptodate(bh))
339				*partial = 1;
340			continue;
341		}
342		err = (*fn)(handle, bh);
343		if (!ret)
344			ret = err;
345	}
346	return ret;
347}
348
349handle_t *ocfs2_start_walk_page_trans(struct inode *inode,
350							 struct page *page,
351							 unsigned from,
352							 unsigned to)
353{
354	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
355	handle_t *handle = NULL;
356	int ret = 0;
357
358	handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
359	if (!handle) {
360		ret = -ENOMEM;
361		mlog_errno(ret);
362		goto out;
363	}
364
365	if (ocfs2_should_order_data(inode)) {
366		ret = walk_page_buffers(handle,
367					page_buffers(page),
368					from, to, NULL,
369					ocfs2_journal_dirty_data);
370		if (ret < 0)
371			mlog_errno(ret);
372	}
373out:
374	if (ret) {
375		if (handle)
376			ocfs2_commit_trans(osb, handle);
377		handle = ERR_PTR(ret);
378	}
379	return handle;
380}
381
382static sector_t ocfs2_bmap(struct address_space *mapping, sector_t block)
383{
384	sector_t status;
385	u64 p_blkno = 0;
386	int err = 0;
387	struct inode *inode = mapping->host;
388
389	mlog_entry("(block = %llu)\n", (unsigned long long)block);
390
391	/* We don't need to lock journal system files, since they aren't
392	 * accessed concurrently from multiple nodes.
393	 */
394	if (!INODE_JOURNAL(inode)) {
395		err = ocfs2_meta_lock(inode, NULL, 0);
396		if (err) {
397			if (err != -ENOENT)
398				mlog_errno(err);
399			goto bail;
400		}
401		down_read(&OCFS2_I(inode)->ip_alloc_sem);
402	}
403
404	err = ocfs2_extent_map_get_blocks(inode, block, &p_blkno, NULL, NULL);
405
406	if (!INODE_JOURNAL(inode)) {
407		up_read(&OCFS2_I(inode)->ip_alloc_sem);
408		ocfs2_meta_unlock(inode, 0);
409	}
410
411	if (err) {
412		mlog(ML_ERROR, "get_blocks() failed, block = %llu\n",
413		     (unsigned long long)block);
414		mlog_errno(err);
415		goto bail;
416	}
417
418
419bail:
420	status = err ? 0 : p_blkno;
421
422	mlog_exit((int)status);
423
424	return status;
425}
426
427/*
428 * TODO: Make this into a generic get_blocks function.
429 *
430 * From do_direct_io in direct-io.c:
431 *  "So what we do is to permit the ->get_blocks function to populate
432 *   bh.b_size with the size of IO which is permitted at this offset and
433 *   this i_blkbits."
434 *
435 * This function is called directly from get_more_blocks in direct-io.c.
436 *
437 * called like this: dio->get_blocks(dio->inode, fs_startblk,
438 * 					fs_count, map_bh, dio->rw == WRITE);
439 */
440static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock,
441				     struct buffer_head *bh_result, int create)
442{
443	int ret;
444	u64 p_blkno, inode_blocks, contig_blocks;
445	unsigned int ext_flags;
446	unsigned char blocksize_bits = inode->i_sb->s_blocksize_bits;
447	unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
448
449	/* This function won't even be called if the request isn't all
450	 * nicely aligned and of the right size, so there's no need
451	 * for us to check any of that. */
452
453	inode_blocks = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));
454
455	/*
456	 * Any write past EOF is not allowed because we'd be extending.
457	 */
458	if (create && (iblock + max_blocks) > inode_blocks) {
459		ret = -EIO;
460		goto bail;
461	}
462
463	/* This figures out the size of the next contiguous block, and
464	 * our logical offset */
465	ret = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno,
466					  &contig_blocks, &ext_flags);
467	if (ret) {
468		mlog(ML_ERROR, "get_blocks() failed iblock=%llu\n",
469		     (unsigned long long)iblock);
470		ret = -EIO;
471		goto bail;
472	}
473
474	if (!ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)) && !p_blkno) {
475		ocfs2_error(inode->i_sb,
476			    "Inode %llu has a hole at block %llu\n",
477			    (unsigned long long)OCFS2_I(inode)->ip_blkno,
478			    (unsigned long long)iblock);
479		ret = -EROFS;
480		goto bail;
481	}
482
483	/*
484	 * get_more_blocks() expects us to describe a hole by clearing
485	 * the mapped bit on bh_result().
486	 *
487	 * Consider an unwritten extent as a hole.
488	 */
489	if (p_blkno && !(ext_flags & OCFS2_EXT_UNWRITTEN))
490		map_bh(bh_result, inode->i_sb, p_blkno);
491	else {
492		/*
493		 * ocfs2_prepare_inode_for_write() should have caught
494		 * the case where we'd be filling a hole and triggered
495		 * a buffered write instead.
496		 */
497		if (create) {
498			ret = -EIO;
499			mlog_errno(ret);
500			goto bail;
501		}
502
503		clear_buffer_mapped(bh_result);
504	}
505
506	/* make sure we don't map more than max_blocks blocks here as
507	   that's all the kernel will handle at this point. */
508	if (max_blocks < contig_blocks)
509		contig_blocks = max_blocks;
510	bh_result->b_size = contig_blocks << blocksize_bits;
511bail:
512	return ret;
513}
514
515/*
516 * ocfs2_dio_end_io is called by the dio core when a dio is finished.  We're
517 * particularly interested in the aio/dio case.  Like the core uses
518 * i_alloc_sem, we use the rw_lock DLM lock to protect io on one node from
519 * truncation on another.
520 */
521static void ocfs2_dio_end_io(struct kiocb *iocb,
522			     loff_t offset,
523			     ssize_t bytes,
524			     void *private)
525{
526	struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
527	int level;
528
529	/* this io's submitter should not have unlocked this before we could */
530	BUG_ON(!ocfs2_iocb_is_rw_locked(iocb));
531
532	ocfs2_iocb_clear_rw_locked(iocb);
533
534	level = ocfs2_iocb_rw_locked_level(iocb);
535	if (!level)
536		up_read(&inode->i_alloc_sem);
537	ocfs2_rw_unlock(inode, level);
538}
539
540/*
541 * ocfs2_invalidatepage() and ocfs2_releasepage() are shamelessly stolen
542 * from ext3.  PageChecked() bits have been removed as OCFS2 does not
543 * do journalled data.
544 */
545static void ocfs2_invalidatepage(struct page *page, unsigned long offset)
546{
547	journal_t *journal = OCFS2_SB(page->mapping->host->i_sb)->journal->j_journal;
548
549	journal_invalidatepage(journal, page, offset);
550}
551
552static int ocfs2_releasepage(struct page *page, gfp_t wait)
553{
554	journal_t *journal = OCFS2_SB(page->mapping->host->i_sb)->journal->j_journal;
555
556	if (!page_has_buffers(page))
557		return 0;
558	return journal_try_to_free_buffers(journal, page, wait);
559}
560
561static ssize_t ocfs2_direct_IO(int rw,
562			       struct kiocb *iocb,
563			       const struct iovec *iov,
564			       loff_t offset,
565			       unsigned long nr_segs)
566{
567	struct file *file = iocb->ki_filp;
568	struct inode *inode = file->f_path.dentry->d_inode->i_mapping->host;
569	int ret;
570
571	mlog_entry_void();
572
573	if (!ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb))) {
574		/*
575		 * We get PR data locks even for O_DIRECT.  This
576		 * allows concurrent O_DIRECT I/O but doesn't let
577		 * O_DIRECT with extending and buffered zeroing writes
578		 * race.  If they did race then the buffered zeroing
579		 * could be written back after the O_DIRECT I/O.  It's
580		 * one thing to tell people not to mix buffered and
581		 * O_DIRECT writes, but expecting them to understand
582		 * that file extension is also an implicit buffered
583		 * write is too much.  By getting the PR we force
584		 * writeback of the buffered zeroing before
585		 * proceeding.
586		 */
587		ret = ocfs2_data_lock(inode, 0);
588		if (ret < 0) {
589			mlog_errno(ret);
590			goto out;
591		}
592		ocfs2_data_unlock(inode, 0);
593	}
594
595	ret = blockdev_direct_IO_no_locking(rw, iocb, inode,
596					    inode->i_sb->s_bdev, iov, offset,
597					    nr_segs,
598					    ocfs2_direct_IO_get_blocks,
599					    ocfs2_dio_end_io);
600out:
601	mlog_exit(ret);
602	return ret;
603}
604
605static void ocfs2_figure_cluster_boundaries(struct ocfs2_super *osb,
606					    u32 cpos,
607					    unsigned int *start,
608					    unsigned int *end)
609{
610	unsigned int cluster_start = 0, cluster_end = PAGE_CACHE_SIZE;
611
612	if (unlikely(PAGE_CACHE_SHIFT > osb->s_clustersize_bits)) {
613		unsigned int cpp;
614
615		cpp = 1 << (PAGE_CACHE_SHIFT - osb->s_clustersize_bits);
616
617		cluster_start = cpos % cpp;
618		cluster_start = cluster_start << osb->s_clustersize_bits;
619
620		cluster_end = cluster_start + osb->s_clustersize;
621	}
622
623	BUG_ON(cluster_start > PAGE_SIZE);
624	BUG_ON(cluster_end > PAGE_SIZE);
625
626	if (start)
627		*start = cluster_start;
628	if (end)
629		*end = cluster_end;
630}
631
632/*
633 * 'from' and 'to' are the region in the page to avoid zeroing.
634 *
635 * If pagesize > clustersize, this function will avoid zeroing outside
636 * of the cluster boundary.
637 *
638 * from == to == 0 is code for "zero the entire cluster region"
639 */
640static void ocfs2_clear_page_regions(struct page *page,
641				     struct ocfs2_super *osb, u32 cpos,
642				     unsigned from, unsigned to)
643{
644	void *kaddr;
645	unsigned int cluster_start, cluster_end;
646
647	ocfs2_figure_cluster_boundaries(osb, cpos, &cluster_start, &cluster_end);
648
649	kaddr = kmap_atomic(page, KM_USER0);
650
651	if (from || to) {
652		if (from > cluster_start)
653			memset(kaddr + cluster_start, 0, from - cluster_start);
654		if (to < cluster_end)
655			memset(kaddr + to, 0, cluster_end - to);
656	} else {
657		memset(kaddr + cluster_start, 0, cluster_end - cluster_start);
658	}
659
660	kunmap_atomic(kaddr, KM_USER0);
661}
662
663/*
664 * Some of this taken from block_prepare_write(). We already have our
665 * mapping by now though, and the entire write will be allocating or
666 * it won't, so not much need to use BH_New.
667 *
668 * This will also skip zeroing, which is handled externally.
669 */
670int ocfs2_map_page_blocks(struct page *page, u64 *p_blkno,
671			  struct inode *inode, unsigned int from,
672			  unsigned int to, int new)
673{
674	int ret = 0;
675	struct buffer_head *head, *bh, *wait[2], **wait_bh = wait;
676	unsigned int block_end, block_start;
677	unsigned int bsize = 1 << inode->i_blkbits;
678
679	if (!page_has_buffers(page))
680		create_empty_buffers(page, bsize, 0);
681
682	head = page_buffers(page);
683	for (bh = head, block_start = 0; bh != head || !block_start;
684	     bh = bh->b_this_page, block_start += bsize) {
685		block_end = block_start + bsize;
686
687		clear_buffer_new(bh);
688
689		/*
690		 * Ignore blocks outside of our i/o range -
691		 * they may belong to unallocated clusters.
692		 */
693		if (block_start >= to || block_end <= from) {
694			if (PageUptodate(page))
695				set_buffer_uptodate(bh);
696			continue;
697		}
698
699		/*
700		 * For an allocating write with cluster size >= page
701		 * size, we always write the entire page.
702		 */
703		if (new)
704			set_buffer_new(bh);
705
706		if (!buffer_mapped(bh)) {
707			map_bh(bh, inode->i_sb, *p_blkno);
708			unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
709		}
710
711		if (PageUptodate(page)) {
712			if (!buffer_uptodate(bh))
713				set_buffer_uptodate(bh);
714		} else if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
715			   !buffer_new(bh) &&
716			   (block_start < from || block_end > to)) {
717			ll_rw_block(READ, 1, &bh);
718			*wait_bh++=bh;
719		}
720
721		*p_blkno = *p_blkno + 1;
722	}
723
724	/*
725	 * If we issued read requests - let them complete.
726	 */
727	while(wait_bh > wait) {
728		wait_on_buffer(*--wait_bh);
729		if (!buffer_uptodate(*wait_bh))
730			ret = -EIO;
731	}
732
733	if (ret == 0 || !new)
734		return ret;
735
736	/*
737	 * If we get -EIO above, zero out any newly allocated blocks
738	 * to avoid exposing stale data.
739	 */
740	bh = head;
741	block_start = 0;
742	do {
743		block_end = block_start + bsize;
744		if (block_end <= from)
745			goto next_bh;
746		if (block_start >= to)
747			break;
748
749		zero_user_page(page, block_start, bh->b_size, KM_USER0);
750		set_buffer_uptodate(bh);
751		mark_buffer_dirty(bh);
752
753next_bh:
754		block_start = block_end;
755		bh = bh->b_this_page;
756	} while (bh != head);
757
758	return ret;
759}
760
761#if (PAGE_CACHE_SIZE >= OCFS2_MAX_CLUSTERSIZE)
762#define OCFS2_MAX_CTXT_PAGES	1
763#else
764#define OCFS2_MAX_CTXT_PAGES	(OCFS2_MAX_CLUSTERSIZE / PAGE_CACHE_SIZE)
765#endif
766
767#define OCFS2_MAX_CLUSTERS_PER_PAGE	(PAGE_CACHE_SIZE / OCFS2_MIN_CLUSTERSIZE)
768
769/*
770 * Describe the state of a single cluster to be written to.
771 */
772struct ocfs2_write_cluster_desc {
773	u32		c_cpos;
774	u32		c_phys;
775	/*
776	 * Give this a unique field because c_phys eventually gets
777	 * filled.
778	 */
779	unsigned	c_new;
780	unsigned	c_unwritten;
781};
782
783static inline int ocfs2_should_zero_cluster(struct ocfs2_write_cluster_desc *d)
784{
785	return d->c_new || d->c_unwritten;
786}
787
788struct ocfs2_write_ctxt {
789	/* Logical cluster position / len of write */
790	u32				w_cpos;
791	u32				w_clen;
792
793	struct ocfs2_write_cluster_desc	w_desc[OCFS2_MAX_CLUSTERS_PER_PAGE];
794
795	/*
796	 * This is true if page_size > cluster_size.
797	 *
798	 * It triggers a set of special cases during write which might
799	 * have to deal with allocating writes to partial pages.
800	 */
801	unsigned int			w_large_pages;
802
803	/*
804	 * Pages involved in this write.
805	 *
806	 * w_target_page is the page being written to by the user.
807	 *
808	 * w_pages is an array of pages which always contains
809	 * w_target_page, and in the case of an allocating write with
810	 * page_size < cluster size, it will contain zero'd and mapped
811	 * pages adjacent to w_target_page which need to be written
812	 * out in so that future reads from that region will get
813	 * zero's.
814	 */
815	struct page			*w_pages[OCFS2_MAX_CTXT_PAGES];
816	unsigned int			w_num_pages;
817	struct page			*w_target_page;
818
819	/*
820	 * ocfs2_write_end() uses this to know what the real range to
821	 * write in the target should be.
822	 */
823	unsigned int			w_target_from;
824	unsigned int			w_target_to;
825
826	/*
827	 * We could use journal_current_handle() but this is cleaner,
828	 * IMHO -Mark
829	 */
830	handle_t			*w_handle;
831
832	struct buffer_head		*w_di_bh;
833
834	struct ocfs2_cached_dealloc_ctxt w_dealloc;
835};
836
837static void ocfs2_free_write_ctxt(struct ocfs2_write_ctxt *wc)
838{
839	int i;
840
841	for(i = 0; i < wc->w_num_pages; i++) {
842		if (wc->w_pages[i] == NULL)
843			continue;
844
845		unlock_page(wc->w_pages[i]);
846		mark_page_accessed(wc->w_pages[i]);
847		page_cache_release(wc->w_pages[i]);
848	}
849
850	brelse(wc->w_di_bh);
851	kfree(wc);
852}
853
854static int ocfs2_alloc_write_ctxt(struct ocfs2_write_ctxt **wcp,
855				  struct ocfs2_super *osb, loff_t pos,
856				  unsigned len, struct buffer_head *di_bh)
857{
858	struct ocfs2_write_ctxt *wc;
859
860	wc = kzalloc(sizeof(struct ocfs2_write_ctxt), GFP_NOFS);
861	if (!wc)
862		return -ENOMEM;
863
864	wc->w_cpos = pos >> osb->s_clustersize_bits;
865	wc->w_clen = ocfs2_clusters_for_bytes(osb->sb, len);
866	get_bh(di_bh);
867	wc->w_di_bh = di_bh;
868
869	if (unlikely(PAGE_CACHE_SHIFT > osb->s_clustersize_bits))
870		wc->w_large_pages = 1;
871	else
872		wc->w_large_pages = 0;
873
874	ocfs2_init_dealloc_ctxt(&wc->w_dealloc);
875
876	*wcp = wc;
877
878	return 0;
879}
880
881/*
882 * If a page has any new buffers, zero them out here, and mark them uptodate
883 * and dirty so they'll be written out (in order to prevent uninitialised
884 * block data from leaking). And clear the new bit.
885 */
886static void ocfs2_zero_new_buffers(struct page *page, unsigned from, unsigned to)
887{
888	unsigned int block_start, block_end;
889	struct buffer_head *head, *bh;
890
891	BUG_ON(!PageLocked(page));
892	if (!page_has_buffers(page))
893		return;
894
895	bh = head = page_buffers(page);
896	block_start = 0;
897	do {
898		block_end = block_start + bh->b_size;
899
900		if (buffer_new(bh)) {
901			if (block_end > from && block_start < to) {
902				if (!PageUptodate(page)) {
903					unsigned start, end;
904
905					start = max(from, block_start);
906					end = min(to, block_end);
907
908					zero_user_page(page, start, end - start, KM_USER0);
909					set_buffer_uptodate(bh);
910				}
911
912				clear_buffer_new(bh);
913				mark_buffer_dirty(bh);
914			}
915		}
916
917		block_start = block_end;
918		bh = bh->b_this_page;
919	} while (bh != head);
920}
921
922/*
923 * Only called when we have a failure during allocating write to write
924 * zero's to the newly allocated region.
925 */
926static void ocfs2_write_failure(struct inode *inode,
927				struct ocfs2_write_ctxt *wc,
928				loff_t user_pos, unsigned user_len)
929{
930	int i;
931	unsigned from, to;
932	struct page *tmppage;
933
934	ocfs2_zero_new_buffers(wc->w_target_page, user_pos, user_len);
935
936	if (wc->w_large_pages) {
937		from = wc->w_target_from;
938		to = wc->w_target_to;
939	} else {
940		from = 0;
941		to = PAGE_CACHE_SIZE;
942	}
943
944	for(i = 0; i < wc->w_num_pages; i++) {
945		tmppage = wc->w_pages[i];
946
947		if (ocfs2_should_order_data(inode))
948			walk_page_buffers(wc->w_handle, page_buffers(tmppage),
949					  from, to, NULL,
950					  ocfs2_journal_dirty_data);
951
952		block_commit_write(tmppage, from, to);
953	}
954}
955
956static int ocfs2_prepare_page_for_write(struct inode *inode, u64 *p_blkno,
957					struct ocfs2_write_ctxt *wc,
958					struct page *page, u32 cpos,
959					loff_t user_pos, unsigned user_len,
960					int new)
961{
962	int ret;
963	unsigned int map_from = 0, map_to = 0;
964	unsigned int cluster_start, cluster_end;
965	unsigned int user_data_from = 0, user_data_to = 0;
966
967	ocfs2_figure_cluster_boundaries(OCFS2_SB(inode->i_sb), cpos,
968					&cluster_start, &cluster_end);
969
970	if (page == wc->w_target_page) {
971		map_from = user_pos & (PAGE_CACHE_SIZE - 1);
972		map_to = map_from + user_len;
973
974		if (new)
975			ret = ocfs2_map_page_blocks(page, p_blkno, inode,
976						    cluster_start, cluster_end,
977						    new);
978		else
979			ret = ocfs2_map_page_blocks(page, p_blkno, inode,
980						    map_from, map_to, new);
981		if (ret) {
982			mlog_errno(ret);
983			goto out;
984		}
985
986		user_data_from = map_from;
987		user_data_to = map_to;
988		if (new) {
989			map_from = cluster_start;
990			map_to = cluster_end;
991		}
992
993		wc->w_target_from = map_from;
994		wc->w_target_to = map_to;
995	} else {
996		/*
997		 * If we haven't allocated the new page yet, we
998		 * shouldn't be writing it out without copying user
999		 * data. This is likely a math error from the caller.
1000		 */
1001		BUG_ON(!new);
1002
1003		map_from = cluster_start;
1004		map_to = cluster_end;
1005
1006		ret = ocfs2_map_page_blocks(page, p_blkno, inode,
1007					    cluster_start, cluster_end, new);
1008		if (ret) {
1009			mlog_errno(ret);
1010			goto out;
1011		}
1012	}
1013
1014	/*
1015	 * Parts of newly allocated pages need to be zero'd.
1016	 *
1017	 * Above, we have also rewritten 'to' and 'from' - as far as
1018	 * the rest of the function is concerned, the entire cluster
1019	 * range inside of a page needs to be written.
1020	 *
1021	 * We can skip this if the page is up to date - it's already
1022	 * been zero'd from being read in as a hole.
1023	 */
1024	if (new && !PageUptodate(page))
1025		ocfs2_clear_page_regions(page, OCFS2_SB(inode->i_sb),
1026					 cpos, user_data_from, user_data_to);
1027
1028	flush_dcache_page(page);
1029
1030out:
1031	return ret;
1032}
1033
1034/*
1035 * This function will only grab one clusters worth of pages.
1036 */
1037static int ocfs2_grab_pages_for_write(struct address_space *mapping,
1038				      struct ocfs2_write_ctxt *wc,
1039				      u32 cpos, loff_t user_pos, int new,
1040				      struct page *mmap_page)
1041{
1042	int ret = 0, i;
1043	unsigned long start, target_index, index;
1044	struct inode *inode = mapping->host;
1045
1046	target_index = user_pos >> PAGE_CACHE_SHIFT;
1047
1048	/*
1049	 * Figure out how many pages we'll be manipulating here. For
1050	 * non allocating write, we just change the one
1051	 * page. Otherwise, we'll need a whole clusters worth.
1052	 */
1053	if (new) {
1054		wc->w_num_pages = ocfs2_pages_per_cluster(inode->i_sb);
1055		start = ocfs2_align_clusters_to_page_index(inode->i_sb, cpos);
1056	} else {
1057		wc->w_num_pages = 1;
1058		start = target_index;
1059	}
1060
1061	for(i = 0; i < wc->w_num_pages; i++) {
1062		index = start + i;
1063
1064		if (index == target_index && mmap_page) {
1065			/*
1066			 * ocfs2_pagemkwrite() is a little different
1067			 * and wants us to directly use the page
1068			 * passed in.
1069			 */
1070			lock_page(mmap_page);
1071
1072			if (mmap_page->mapping != mapping) {
1073				unlock_page(mmap_page);
1074				/*
1075				 * Sanity check - the locking in
1076				 * ocfs2_pagemkwrite() should ensure
1077				 * that this code doesn't trigger.
1078				 */
1079				ret = -EINVAL;
1080				mlog_errno(ret);
1081				goto out;
1082			}
1083
1084			page_cache_get(mmap_page);
1085			wc->w_pages[i] = mmap_page;
1086		} else {
1087			wc->w_pages[i] = find_or_create_page(mapping, index,
1088							     GFP_NOFS);
1089			if (!wc->w_pages[i]) {
1090				ret = -ENOMEM;
1091				mlog_errno(ret);
1092				goto out;
1093			}
1094		}
1095
1096		if (index == target_index)
1097			wc->w_target_page = wc->w_pages[i];
1098	}
1099out:
1100	return ret;
1101}
1102
1103/*
1104 * Prepare a single cluster for write one cluster into the file.
1105 */
1106static int ocfs2_write_cluster(struct address_space *mapping,
1107			       u32 phys, unsigned int unwritten,
1108			       struct ocfs2_alloc_context *data_ac,
1109			       struct ocfs2_alloc_context *meta_ac,
1110			       struct ocfs2_write_ctxt *wc, u32 cpos,
1111			       loff_t user_pos, unsigned user_len)
1112{
1113	int ret, i, new, should_zero = 0;
1114	u64 v_blkno, p_blkno;
1115	struct inode *inode = mapping->host;
1116
1117	new = phys == 0 ? 1 : 0;
1118	if (new || unwritten)
1119		should_zero = 1;
1120
1121	if (new) {
1122		u32 tmp_pos;
1123
1124		/*
1125		 * This is safe to call with the page locks - it won't take
1126		 * any additional semaphores or cluster locks.
1127		 */
1128		tmp_pos = cpos;
1129		ret = ocfs2_do_extend_allocation(OCFS2_SB(inode->i_sb), inode,
1130						 &tmp_pos, 1, 0, wc->w_di_bh,
1131						 wc->w_handle, data_ac,
1132						 meta_ac, NULL);
1133		/*
1134		 * This shouldn't happen because we must have already
1135		 * calculated the correct meta data allocation required. The
1136		 * internal tree allocation code should know how to increase
1137		 * transaction credits itself.
1138		 *
1139		 * If need be, we could handle -EAGAIN for a
1140		 * RESTART_TRANS here.
1141		 */
1142		mlog_bug_on_msg(ret == -EAGAIN,
1143				"Inode %llu: EAGAIN return during allocation.\n",
1144				(unsigned long long)OCFS2_I(inode)->ip_blkno);
1145		if (ret < 0) {
1146			mlog_errno(ret);
1147			goto out;
1148		}
1149	} else if (unwritten) {
1150		ret = ocfs2_mark_extent_written(inode, wc->w_di_bh,
1151						wc->w_handle, cpos, 1, phys,
1152						meta_ac, &wc->w_dealloc);
1153		if (ret < 0) {
1154			mlog_errno(ret);
1155			goto out;
1156		}
1157	}
1158
1159	if (should_zero)
1160		v_blkno = ocfs2_clusters_to_blocks(inode->i_sb, cpos);
1161	else
1162		v_blkno = user_pos >> inode->i_sb->s_blocksize_bits;
1163
1164	/*
1165	 * The only reason this should fail is due to an inability to
1166	 * find the extent added.
1167	 */
1168	ret = ocfs2_extent_map_get_blocks(inode, v_blkno, &p_blkno, NULL,
1169					  NULL);
1170	if (ret < 0) {
1171		ocfs2_error(inode->i_sb, "Corrupting extend for inode %llu, "
1172			    "at logical block %llu",
1173			    (unsigned long long)OCFS2_I(inode)->ip_blkno,
1174			    (unsigned long long)v_blkno);
1175		goto out;
1176	}
1177
1178	BUG_ON(p_blkno == 0);
1179
1180	for(i = 0; i < wc->w_num_pages; i++) {
1181		int tmpret;
1182
1183		tmpret = ocfs2_prepare_page_for_write(inode, &p_blkno, wc,
1184						      wc->w_pages[i], cpos,
1185						      user_pos, user_len,
1186						      should_zero);
1187		if (tmpret) {
1188			mlog_errno(tmpret);
1189			if (ret == 0)
1190				tmpret = ret;
1191		}
1192	}
1193
1194	/*
1195	 * We only have cleanup to do in case of allocating write.
1196	 */
1197	if (ret && new)
1198		ocfs2_write_failure(inode, wc, user_pos, user_len);
1199
1200out:
1201
1202	return ret;
1203}
1204
1205static int ocfs2_write_cluster_by_desc(struct address_space *mapping,
1206				       struct ocfs2_alloc_context *data_ac,
1207				       struct ocfs2_alloc_context *meta_ac,
1208				       struct ocfs2_write_ctxt *wc,
1209				       loff_t pos, unsigned len)
1210{
1211	int ret, i;
1212	struct ocfs2_write_cluster_desc *desc;
1213
1214	for (i = 0; i < wc->w_clen; i++) {
1215		desc = &wc->w_desc[i];
1216
1217		ret = ocfs2_write_cluster(mapping, desc->c_phys,
1218					  desc->c_unwritten, data_ac, meta_ac,
1219					  wc, desc->c_cpos, pos, len);
1220		if (ret) {
1221			mlog_errno(ret);
1222			goto out;
1223		}
1224	}
1225
1226	ret = 0;
1227out:
1228	return ret;
1229}
1230
1231/*
1232 * ocfs2_write_end() wants to know which parts of the target page it
1233 * should complete the write on. It's easiest to compute them ahead of
1234 * time when a more complete view of the write is available.
1235 */
1236static void ocfs2_set_target_boundaries(struct ocfs2_super *osb,
1237					struct ocfs2_write_ctxt *wc,
1238					loff_t pos, unsigned len, int alloc)
1239{
1240	struct ocfs2_write_cluster_desc *desc;
1241
1242	wc->w_target_from = pos & (PAGE_CACHE_SIZE - 1);
1243	wc->w_target_to = wc->w_target_from + len;
1244
1245	if (alloc == 0)
1246		return;
1247
1248	/*
1249	 * Allocating write - we may have different boundaries based
1250	 * on page size and cluster size.
1251	 *
1252	 * NOTE: We can no longer compute one value from the other as
1253	 * the actual write length and user provided length may be
1254	 * different.
1255	 */
1256
1257	if (wc->w_large_pages) {
1258		/*
1259		 * We only care about the 1st and last cluster within
1260		 * our range and whether they should be zero'd or not. Either
1261		 * value may be extended out to the start/end of a
1262		 * newly allocated cluster.
1263		 */
1264		desc = &wc->w_desc[0];
1265		if (ocfs2_should_zero_cluster(desc))
1266			ocfs2_figure_cluster_boundaries(osb,
1267							desc->c_cpos,
1268							&wc->w_target_from,
1269							NULL);
1270
1271		desc = &wc->w_desc[wc->w_clen - 1];
1272		if (ocfs2_should_zero_cluster(desc))
1273			ocfs2_figure_cluster_boundaries(osb,
1274							desc->c_cpos,
1275							NULL,
1276							&wc->w_target_to);
1277	} else {
1278		wc->w_target_from = 0;
1279		wc->w_target_to = PAGE_CACHE_SIZE;
1280	}
1281}
1282
1283/*
1284 * Populate each single-cluster write descriptor in the write context
1285 * with information about the i/o to be done.
1286 *
1287 * Returns the number of clusters that will have to be allocated, as
1288 * well as a worst case estimate of the number of extent records that
1289 * would have to be created during a write to an unwritten region.
1290 */
1291static int ocfs2_populate_write_desc(struct inode *inode,
1292				     struct ocfs2_write_ctxt *wc,
1293				     unsigned int *clusters_to_alloc,
1294				     unsigned int *extents_to_split)
1295{
1296	int ret;
1297	struct ocfs2_write_cluster_desc *desc;
1298	unsigned int num_clusters = 0;
1299	unsigned int ext_flags = 0;
1300	u32 phys = 0;
1301	int i;
1302
1303	*clusters_to_alloc = 0;
1304	*extents_to_split = 0;
1305
1306	for (i = 0; i < wc->w_clen; i++) {
1307		desc = &wc->w_desc[i];
1308		desc->c_cpos = wc->w_cpos + i;
1309
1310		if (num_clusters == 0) {
1311			/*
1312			 * Need to look up the next extent record.
1313			 */
1314			ret = ocfs2_get_clusters(inode, desc->c_cpos, &phys,
1315						 &num_clusters, &ext_flags);
1316			if (ret) {
1317				mlog_errno(ret);
1318				goto out;
1319			}
1320
1321			/*
1322			 * Assume worst case - that we're writing in
1323			 * the middle of the extent.
1324			 *
1325			 * We can assume that the write proceeds from
1326			 * left to right, in which case the extent
1327			 * insert code is smart enough to coalesce the
1328			 * next splits into the previous records created.
1329			 */
1330			if (ext_flags & OCFS2_EXT_UNWRITTEN)
1331				*extents_to_split = *extents_to_split + 2;
1332		} else if (phys) {
1333			/*
1334			 * Only increment phys if it doesn't describe
1335			 * a hole.
1336			 */
1337			phys++;
1338		}
1339
1340		desc->c_phys = phys;
1341		if (phys == 0) {
1342			desc->c_new = 1;
1343			*clusters_to_alloc = *clusters_to_alloc + 1;
1344		}
1345		if (ext_flags & OCFS2_EXT_UNWRITTEN)
1346			desc->c_unwritten = 1;
1347
1348		num_clusters--;
1349	}
1350
1351	ret = 0;
1352out:
1353	return ret;
1354}
1355
1356int ocfs2_write_begin_nolock(struct address_space *mapping,
1357			     loff_t pos, unsigned len, unsigned flags,
1358			     struct page **pagep, void **fsdata,
1359			     struct buffer_head *di_bh, struct page *mmap_page)
1360{
1361	int ret, credits = OCFS2_INODE_UPDATE_CREDITS;
1362	unsigned int clusters_to_alloc, extents_to_split;
1363	struct ocfs2_write_ctxt *wc;
1364	struct inode *inode = mapping->host;
1365	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
1366	struct ocfs2_dinode *di;
1367	struct ocfs2_alloc_context *data_ac = NULL;
1368	struct ocfs2_alloc_context *meta_ac = NULL;
1369	handle_t *handle;
1370
1371	ret = ocfs2_alloc_write_ctxt(&wc, osb, pos, len, di_bh);
1372	if (ret) {
1373		mlog_errno(ret);
1374		return ret;
1375	}
1376
1377	ret = ocfs2_populate_write_desc(inode, wc, &clusters_to_alloc,
1378					&extents_to_split);
1379	if (ret) {
1380		mlog_errno(ret);
1381		goto out;
1382	}
1383
1384	di = (struct ocfs2_dinode *)wc->w_di_bh->b_data;
1385
1386	/*
1387	 * We set w_target_from, w_target_to here so that
1388	 * ocfs2_write_end() knows which range in the target page to
1389	 * write out. An allocation requires that we write the entire
1390	 * cluster range.
1391	 */
1392	if (clusters_to_alloc || extents_to_split) {
1393		/*
1394		 * XXX: We are stretching the limits of
1395		 * ocfs2_lock_allocators(). It greatly over-estimates
1396		 * the work to be done.
1397		 */
1398		ret = ocfs2_lock_allocators(inode, di, clusters_to_alloc,
1399					    extents_to_split, &data_ac, &meta_ac);
1400		if (ret) {
1401			mlog_errno(ret);
1402			goto out;
1403		}
1404
1405		credits = ocfs2_calc_extend_credits(inode->i_sb, di,
1406						    clusters_to_alloc);
1407
1408	}
1409
1410	ocfs2_set_target_boundaries(osb, wc, pos, len,
1411				    clusters_to_alloc + extents_to_split);
1412
1413	handle = ocfs2_start_trans(osb, credits);
1414	if (IS_ERR(handle)) {
1415		ret = PTR_ERR(handle);
1416		mlog_errno(ret);
1417		goto out;
1418	}
1419
1420	wc->w_handle = handle;
1421
1422	/*
1423	 * We don't want this to fail in ocfs2_write_end(), so do it
1424	 * here.
1425	 */
1426	ret = ocfs2_journal_access(handle, inode, wc->w_di_bh,
1427				   OCFS2_JOURNAL_ACCESS_WRITE);
1428	if (ret) {
1429		mlog_errno(ret);
1430		goto out_commit;
1431	}
1432
1433	/*
1434	 * Fill our page array first. That way we've grabbed enough so
1435	 * that we can zero and flush if we error after adding the
1436	 * extent.
1437	 */
1438	ret = ocfs2_grab_pages_for_write(mapping, wc, wc->w_cpos, pos,
1439					 clusters_to_alloc + extents_to_split,
1440					 mmap_page);
1441	if (ret) {
1442		mlog_errno(ret);
1443		goto out_commit;
1444	}
1445
1446	ret = ocfs2_write_cluster_by_desc(mapping, data_ac, meta_ac, wc, pos,
1447					  len);
1448	if (ret) {
1449		mlog_errno(ret);
1450		goto out_commit;
1451	}
1452
1453	if (data_ac)
1454		ocfs2_free_alloc_context(data_ac);
1455	if (meta_ac)
1456		ocfs2_free_alloc_context(meta_ac);
1457
1458	*pagep = wc->w_target_page;
1459	*fsdata = wc;
1460	return 0;
1461out_commit:
1462	ocfs2_commit_trans(osb, handle);
1463
1464out:
1465	ocfs2_free_write_ctxt(wc);
1466
1467	if (data_ac)
1468		ocfs2_free_alloc_context(data_ac);
1469	if (meta_ac)
1470		ocfs2_free_alloc_context(meta_ac);
1471	return ret;
1472}
1473
1474int ocfs2_write_begin(struct file *file, struct address_space *mapping,
1475		      loff_t pos, unsigned len, unsigned flags,
1476		      struct page **pagep, void **fsdata)
1477{
1478	int ret;
1479	struct buffer_head *di_bh = NULL;
1480	struct inode *inode = mapping->host;
1481
1482	ret = ocfs2_meta_lock(inode, &di_bh, 1);
1483	if (ret) {
1484		mlog_errno(ret);
1485		return ret;
1486	}
1487
1488	/*
1489	 * Take alloc sem here to prevent concurrent lookups. That way
1490	 * the mapping, zeroing and tree manipulation within
1491	 * ocfs2_write() will be safe against ->readpage(). This
1492	 * should also serve to lock out allocation from a shared
1493	 * writeable region.
1494	 */
1495	down_write(&OCFS2_I(inode)->ip_alloc_sem);
1496
1497	ret = ocfs2_data_lock(inode, 1);
1498	if (ret) {
1499		mlog_errno(ret);
1500		goto out_fail;
1501	}
1502
1503	ret = ocfs2_write_begin_nolock(mapping, pos, len, flags, pagep,
1504				       fsdata, di_bh, NULL);
1505	if (ret) {
1506		mlog_errno(ret);
1507		goto out_fail_data;
1508	}
1509
1510	brelse(di_bh);
1511
1512	return 0;
1513
1514out_fail_data:
1515	ocfs2_data_unlock(inode, 1);
1516out_fail:
1517	up_write(&OCFS2_I(inode)->ip_alloc_sem);
1518
1519	brelse(di_bh);
1520	ocfs2_meta_unlock(inode, 1);
1521
1522	return ret;
1523}
1524
1525int ocfs2_write_end_nolock(struct address_space *mapping,
1526			   loff_t pos, unsigned len, unsigned copied,
1527			   struct page *page, void *fsdata)
1528{
1529	int i;
1530	unsigned from, to, start = pos & (PAGE_CACHE_SIZE - 1);
1531	struct inode *inode = mapping->host;
1532	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
1533	struct ocfs2_write_ctxt *wc = fsdata;
1534	struct ocfs2_dinode *di = (struct ocfs2_dinode *)wc->w_di_bh->b_data;
1535	handle_t *handle = wc->w_handle;
1536	struct page *tmppage;
1537
1538	if (unlikely(copied < len)) {
1539		if (!PageUptodate(wc->w_target_page))
1540			copied = 0;
1541
1542		ocfs2_zero_new_buffers(wc->w_target_page, start+copied,
1543				       start+len);
1544	}
1545	flush_dcache_page(wc->w_target_page);
1546
1547	for(i = 0; i < wc->w_num_pages; i++) {
1548		tmppage = wc->w_pages[i];
1549
1550		if (tmppage == wc->w_target_page) {
1551			from = wc->w_target_from;
1552			to = wc->w_target_to;
1553
1554			BUG_ON(from > PAGE_CACHE_SIZE ||
1555			       to > PAGE_CACHE_SIZE ||
1556			       to < from);
1557		} else {
1558			/*
1559			 * Pages adjacent to the target (if any) imply
1560			 * a hole-filling write in which case we want
1561			 * to flush their entire range.
1562			 */
1563			from = 0;
1564			to = PAGE_CACHE_SIZE;
1565		}
1566
1567		if (ocfs2_should_order_data(inode))
1568			walk_page_buffers(wc->w_handle, page_buffers(tmppage),
1569					  from, to, NULL,
1570					  ocfs2_journal_dirty_data);
1571
1572		block_commit_write(tmppage, from, to);
1573	}
1574
1575	pos += copied;
1576	if (pos > inode->i_size) {
1577		i_size_write(inode, pos);
1578		mark_inode_dirty(inode);
1579	}
1580	inode->i_blocks = ocfs2_inode_sector_count(inode);
1581	di->i_size = cpu_to_le64((u64)i_size_read(inode));
1582	inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1583	di->i_mtime = di->i_ctime = cpu_to_le64(inode->i_mtime.tv_sec);
1584	di->i_mtime_nsec = di->i_ctime_nsec = cpu_to_le32(inode->i_mtime.tv_nsec);
1585	ocfs2_journal_dirty(handle, wc->w_di_bh);
1586
1587	ocfs2_commit_trans(osb, handle);
1588
1589	ocfs2_run_deallocs(osb, &wc->w_dealloc);
1590
1591	ocfs2_free_write_ctxt(wc);
1592
1593	return copied;
1594}
1595
1596int ocfs2_write_end(struct file *file, struct address_space *mapping,
1597		    loff_t pos, unsigned len, unsigned copied,
1598		    struct page *page, void *fsdata)
1599{
1600	int ret;
1601	struct inode *inode = mapping->host;
1602
1603	ret = ocfs2_write_end_nolock(mapping, pos, len, copied, page, fsdata);
1604
1605	ocfs2_data_unlock(inode, 1);
1606	up_write(&OCFS2_I(inode)->ip_alloc_sem);
1607	ocfs2_meta_unlock(inode, 1);
1608
1609	return ret;
1610}
1611
1612const struct address_space_operations ocfs2_aops = {
1613	.readpage	= ocfs2_readpage,
1614	.writepage	= ocfs2_writepage,
1615	.bmap		= ocfs2_bmap,
1616	.sync_page	= block_sync_page,
1617	.direct_IO	= ocfs2_direct_IO,
1618	.invalidatepage	= ocfs2_invalidatepage,
1619	.releasepage	= ocfs2_releasepage,
1620	.migratepage	= buffer_migrate_page,
1621};
1622