xref: /openbmc/linux/fs/ocfs2/aops.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /* -*- mode: c; c-basic-offset: 8; -*-
2  * vim: noexpandtab sw=8 ts=8 sts=0:
3  *
4  * Copyright (C) 2002, 2004 Oracle.  All rights reserved.
5  *
6  * This program is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public
8  * License as published by the Free Software Foundation; either
9  * version 2 of the License, or (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14  * General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public
17  * License along with this program; if not, write to the
18  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
19  * Boston, MA 021110-1307, USA.
20  */
21 
22 #include <linux/fs.h>
23 #include <linux/slab.h>
24 #include <linux/highmem.h>
25 #include <linux/pagemap.h>
26 #include <asm/byteorder.h>
27 #include <linux/swap.h>
28 #include <linux/pipe_fs_i.h>
29 
30 #define MLOG_MASK_PREFIX ML_FILE_IO
31 #include <cluster/masklog.h>
32 
33 #include "ocfs2.h"
34 
35 #include "alloc.h"
36 #include "aops.h"
37 #include "dlmglue.h"
38 #include "extent_map.h"
39 #include "file.h"
40 #include "inode.h"
41 #include "journal.h"
42 #include "suballoc.h"
43 #include "super.h"
44 #include "symlink.h"
45 
46 #include "buffer_head_io.h"
47 
48 static int ocfs2_symlink_get_block(struct inode *inode, sector_t iblock,
49 				   struct buffer_head *bh_result, int create)
50 {
51 	int err = -EIO;
52 	int status;
53 	struct ocfs2_dinode *fe = NULL;
54 	struct buffer_head *bh = NULL;
55 	struct buffer_head *buffer_cache_bh = NULL;
56 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
57 	void *kaddr;
58 
59 	mlog_entry("(0x%p, %llu, 0x%p, %d)\n", inode,
60 		   (unsigned long long)iblock, bh_result, create);
61 
62 	BUG_ON(ocfs2_inode_is_fast_symlink(inode));
63 
64 	if ((iblock << inode->i_sb->s_blocksize_bits) > PATH_MAX + 1) {
65 		mlog(ML_ERROR, "block offset > PATH_MAX: %llu",
66 		     (unsigned long long)iblock);
67 		goto bail;
68 	}
69 
70 	status = ocfs2_read_block(OCFS2_SB(inode->i_sb),
71 				  OCFS2_I(inode)->ip_blkno,
72 				  &bh, OCFS2_BH_CACHED, inode);
73 	if (status < 0) {
74 		mlog_errno(status);
75 		goto bail;
76 	}
77 	fe = (struct ocfs2_dinode *) bh->b_data;
78 
79 	if (!OCFS2_IS_VALID_DINODE(fe)) {
80 		mlog(ML_ERROR, "Invalid dinode #%llu: signature = %.*s\n",
81 		     (unsigned long long)le64_to_cpu(fe->i_blkno), 7,
82 		     fe->i_signature);
83 		goto bail;
84 	}
85 
86 	if ((u64)iblock >= ocfs2_clusters_to_blocks(inode->i_sb,
87 						    le32_to_cpu(fe->i_clusters))) {
88 		mlog(ML_ERROR, "block offset is outside the allocated size: "
89 		     "%llu\n", (unsigned long long)iblock);
90 		goto bail;
91 	}
92 
93 	/* We don't use the page cache to create symlink data, so if
94 	 * need be, copy it over from the buffer cache. */
95 	if (!buffer_uptodate(bh_result) && ocfs2_inode_is_new(inode)) {
96 		u64 blkno = le64_to_cpu(fe->id2.i_list.l_recs[0].e_blkno) +
97 			    iblock;
98 		buffer_cache_bh = sb_getblk(osb->sb, blkno);
99 		if (!buffer_cache_bh) {
100 			mlog(ML_ERROR, "couldn't getblock for symlink!\n");
101 			goto bail;
102 		}
103 
104 		/* we haven't locked out transactions, so a commit
105 		 * could've happened. Since we've got a reference on
106 		 * the bh, even if it commits while we're doing the
107 		 * copy, the data is still good. */
108 		if (buffer_jbd(buffer_cache_bh)
109 		    && ocfs2_inode_is_new(inode)) {
110 			kaddr = kmap_atomic(bh_result->b_page, KM_USER0);
111 			if (!kaddr) {
112 				mlog(ML_ERROR, "couldn't kmap!\n");
113 				goto bail;
114 			}
115 			memcpy(kaddr + (bh_result->b_size * iblock),
116 			       buffer_cache_bh->b_data,
117 			       bh_result->b_size);
118 			kunmap_atomic(kaddr, KM_USER0);
119 			set_buffer_uptodate(bh_result);
120 		}
121 		brelse(buffer_cache_bh);
122 	}
123 
124 	map_bh(bh_result, inode->i_sb,
125 	       le64_to_cpu(fe->id2.i_list.l_recs[0].e_blkno) + iblock);
126 
127 	err = 0;
128 
129 bail:
130 	if (bh)
131 		brelse(bh);
132 
133 	mlog_exit(err);
134 	return err;
135 }
136 
137 static int ocfs2_get_block(struct inode *inode, sector_t iblock,
138 			   struct buffer_head *bh_result, int create)
139 {
140 	int err = 0;
141 	unsigned int ext_flags;
142 	u64 p_blkno, past_eof;
143 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
144 
145 	mlog_entry("(0x%p, %llu, 0x%p, %d)\n", inode,
146 		   (unsigned long long)iblock, bh_result, create);
147 
148 	if (OCFS2_I(inode)->ip_flags & OCFS2_INODE_SYSTEM_FILE)
149 		mlog(ML_NOTICE, "get_block on system inode 0x%p (%lu)\n",
150 		     inode, inode->i_ino);
151 
152 	if (S_ISLNK(inode->i_mode)) {
153 		/* this always does I/O for some reason. */
154 		err = ocfs2_symlink_get_block(inode, iblock, bh_result, create);
155 		goto bail;
156 	}
157 
158 	err = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno, NULL,
159 					  &ext_flags);
160 	if (err) {
161 		mlog(ML_ERROR, "Error %d from get_blocks(0x%p, %llu, 1, "
162 		     "%llu, NULL)\n", err, inode, (unsigned long long)iblock,
163 		     (unsigned long long)p_blkno);
164 		goto bail;
165 	}
166 
167 	/*
168 	 * ocfs2 never allocates in this function - the only time we
169 	 * need to use BH_New is when we're extending i_size on a file
170 	 * system which doesn't support holes, in which case BH_New
171 	 * allows block_prepare_write() to zero.
172 	 */
173 	mlog_bug_on_msg(create && p_blkno == 0 && ocfs2_sparse_alloc(osb),
174 			"ino %lu, iblock %llu\n", inode->i_ino,
175 			(unsigned long long)iblock);
176 
177 	/* Treat the unwritten extent as a hole for zeroing purposes. */
178 	if (p_blkno && !(ext_flags & OCFS2_EXT_UNWRITTEN))
179 		map_bh(bh_result, inode->i_sb, p_blkno);
180 
181 	if (!ocfs2_sparse_alloc(osb)) {
182 		if (p_blkno == 0) {
183 			err = -EIO;
184 			mlog(ML_ERROR,
185 			     "iblock = %llu p_blkno = %llu blkno=(%llu)\n",
186 			     (unsigned long long)iblock,
187 			     (unsigned long long)p_blkno,
188 			     (unsigned long long)OCFS2_I(inode)->ip_blkno);
189 			mlog(ML_ERROR, "Size %llu, clusters %u\n", (unsigned long long)i_size_read(inode), OCFS2_I(inode)->ip_clusters);
190 			dump_stack();
191 		}
192 
193 		past_eof = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));
194 		mlog(0, "Inode %lu, past_eof = %llu\n", inode->i_ino,
195 		     (unsigned long long)past_eof);
196 
197 		if (create && (iblock >= past_eof))
198 			set_buffer_new(bh_result);
199 	}
200 
201 bail:
202 	if (err < 0)
203 		err = -EIO;
204 
205 	mlog_exit(err);
206 	return err;
207 }
208 
209 static int ocfs2_readpage(struct file *file, struct page *page)
210 {
211 	struct inode *inode = page->mapping->host;
212 	loff_t start = (loff_t)page->index << PAGE_CACHE_SHIFT;
213 	int ret, unlock = 1;
214 
215 	mlog_entry("(0x%p, %lu)\n", file, (page ? page->index : 0));
216 
217 	ret = ocfs2_meta_lock_with_page(inode, NULL, 0, page);
218 	if (ret != 0) {
219 		if (ret == AOP_TRUNCATED_PAGE)
220 			unlock = 0;
221 		mlog_errno(ret);
222 		goto out;
223 	}
224 
225 	down_read(&OCFS2_I(inode)->ip_alloc_sem);
226 
227 	/*
228 	 * i_size might have just been updated as we grabed the meta lock.  We
229 	 * might now be discovering a truncate that hit on another node.
230 	 * block_read_full_page->get_block freaks out if it is asked to read
231 	 * beyond the end of a file, so we check here.  Callers
232 	 * (generic_file_read, fault->nopage) are clever enough to check i_size
233 	 * and notice that the page they just read isn't needed.
234 	 *
235 	 * XXX sys_readahead() seems to get that wrong?
236 	 */
237 	if (start >= i_size_read(inode)) {
238 		char *addr = kmap(page);
239 		memset(addr, 0, PAGE_SIZE);
240 		flush_dcache_page(page);
241 		kunmap(page);
242 		SetPageUptodate(page);
243 		ret = 0;
244 		goto out_alloc;
245 	}
246 
247 	ret = ocfs2_data_lock_with_page(inode, 0, page);
248 	if (ret != 0) {
249 		if (ret == AOP_TRUNCATED_PAGE)
250 			unlock = 0;
251 		mlog_errno(ret);
252 		goto out_alloc;
253 	}
254 
255 	ret = block_read_full_page(page, ocfs2_get_block);
256 	unlock = 0;
257 
258 	ocfs2_data_unlock(inode, 0);
259 out_alloc:
260 	up_read(&OCFS2_I(inode)->ip_alloc_sem);
261 	ocfs2_meta_unlock(inode, 0);
262 out:
263 	if (unlock)
264 		unlock_page(page);
265 	mlog_exit(ret);
266 	return ret;
267 }
268 
269 /* Note: Because we don't support holes, our allocation has
270  * already happened (allocation writes zeros to the file data)
271  * so we don't have to worry about ordered writes in
272  * ocfs2_writepage.
273  *
274  * ->writepage is called during the process of invalidating the page cache
275  * during blocked lock processing.  It can't block on any cluster locks
276  * to during block mapping.  It's relying on the fact that the block
277  * mapping can't have disappeared under the dirty pages that it is
278  * being asked to write back.
279  */
280 static int ocfs2_writepage(struct page *page, struct writeback_control *wbc)
281 {
282 	int ret;
283 
284 	mlog_entry("(0x%p)\n", page);
285 
286 	ret = block_write_full_page(page, ocfs2_get_block, wbc);
287 
288 	mlog_exit(ret);
289 
290 	return ret;
291 }
292 
293 /*
294  * This is called from ocfs2_write_zero_page() which has handled it's
295  * own cluster locking and has ensured allocation exists for those
296  * blocks to be written.
297  */
298 int ocfs2_prepare_write_nolock(struct inode *inode, struct page *page,
299 			       unsigned from, unsigned to)
300 {
301 	int ret;
302 
303 	down_read(&OCFS2_I(inode)->ip_alloc_sem);
304 
305 	ret = block_prepare_write(page, from, to, ocfs2_get_block);
306 
307 	up_read(&OCFS2_I(inode)->ip_alloc_sem);
308 
309 	return ret;
310 }
311 
312 /* Taken from ext3. We don't necessarily need the full blown
313  * functionality yet, but IMHO it's better to cut and paste the whole
314  * thing so we can avoid introducing our own bugs (and easily pick up
315  * their fixes when they happen) --Mark */
316 int walk_page_buffers(	handle_t *handle,
317 			struct buffer_head *head,
318 			unsigned from,
319 			unsigned to,
320 			int *partial,
321 			int (*fn)(	handle_t *handle,
322 					struct buffer_head *bh))
323 {
324 	struct buffer_head *bh;
325 	unsigned block_start, block_end;
326 	unsigned blocksize = head->b_size;
327 	int err, ret = 0;
328 	struct buffer_head *next;
329 
330 	for (	bh = head, block_start = 0;
331 		ret == 0 && (bh != head || !block_start);
332 	    	block_start = block_end, bh = next)
333 	{
334 		next = bh->b_this_page;
335 		block_end = block_start + blocksize;
336 		if (block_end <= from || block_start >= to) {
337 			if (partial && !buffer_uptodate(bh))
338 				*partial = 1;
339 			continue;
340 		}
341 		err = (*fn)(handle, bh);
342 		if (!ret)
343 			ret = err;
344 	}
345 	return ret;
346 }
347 
348 handle_t *ocfs2_start_walk_page_trans(struct inode *inode,
349 							 struct page *page,
350 							 unsigned from,
351 							 unsigned to)
352 {
353 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
354 	handle_t *handle = NULL;
355 	int ret = 0;
356 
357 	handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
358 	if (!handle) {
359 		ret = -ENOMEM;
360 		mlog_errno(ret);
361 		goto out;
362 	}
363 
364 	if (ocfs2_should_order_data(inode)) {
365 		ret = walk_page_buffers(handle,
366 					page_buffers(page),
367 					from, to, NULL,
368 					ocfs2_journal_dirty_data);
369 		if (ret < 0)
370 			mlog_errno(ret);
371 	}
372 out:
373 	if (ret) {
374 		if (handle)
375 			ocfs2_commit_trans(osb, handle);
376 		handle = ERR_PTR(ret);
377 	}
378 	return handle;
379 }
380 
381 static sector_t ocfs2_bmap(struct address_space *mapping, sector_t block)
382 {
383 	sector_t status;
384 	u64 p_blkno = 0;
385 	int err = 0;
386 	struct inode *inode = mapping->host;
387 
388 	mlog_entry("(block = %llu)\n", (unsigned long long)block);
389 
390 	/* We don't need to lock journal system files, since they aren't
391 	 * accessed concurrently from multiple nodes.
392 	 */
393 	if (!INODE_JOURNAL(inode)) {
394 		err = ocfs2_meta_lock(inode, NULL, 0);
395 		if (err) {
396 			if (err != -ENOENT)
397 				mlog_errno(err);
398 			goto bail;
399 		}
400 		down_read(&OCFS2_I(inode)->ip_alloc_sem);
401 	}
402 
403 	err = ocfs2_extent_map_get_blocks(inode, block, &p_blkno, NULL, NULL);
404 
405 	if (!INODE_JOURNAL(inode)) {
406 		up_read(&OCFS2_I(inode)->ip_alloc_sem);
407 		ocfs2_meta_unlock(inode, 0);
408 	}
409 
410 	if (err) {
411 		mlog(ML_ERROR, "get_blocks() failed, block = %llu\n",
412 		     (unsigned long long)block);
413 		mlog_errno(err);
414 		goto bail;
415 	}
416 
417 
418 bail:
419 	status = err ? 0 : p_blkno;
420 
421 	mlog_exit((int)status);
422 
423 	return status;
424 }
425 
426 /*
427  * TODO: Make this into a generic get_blocks function.
428  *
429  * From do_direct_io in direct-io.c:
430  *  "So what we do is to permit the ->get_blocks function to populate
431  *   bh.b_size with the size of IO which is permitted at this offset and
432  *   this i_blkbits."
433  *
434  * This function is called directly from get_more_blocks in direct-io.c.
435  *
436  * called like this: dio->get_blocks(dio->inode, fs_startblk,
437  * 					fs_count, map_bh, dio->rw == WRITE);
438  */
439 static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock,
440 				     struct buffer_head *bh_result, int create)
441 {
442 	int ret;
443 	u64 p_blkno, inode_blocks, contig_blocks;
444 	unsigned int ext_flags;
445 	unsigned char blocksize_bits = inode->i_sb->s_blocksize_bits;
446 	unsigned long max_blocks = bh_result->b_size >> inode->i_blkbits;
447 
448 	/* This function won't even be called if the request isn't all
449 	 * nicely aligned and of the right size, so there's no need
450 	 * for us to check any of that. */
451 
452 	inode_blocks = ocfs2_blocks_for_bytes(inode->i_sb, i_size_read(inode));
453 
454 	/*
455 	 * Any write past EOF is not allowed because we'd be extending.
456 	 */
457 	if (create && (iblock + max_blocks) > inode_blocks) {
458 		ret = -EIO;
459 		goto bail;
460 	}
461 
462 	/* This figures out the size of the next contiguous block, and
463 	 * our logical offset */
464 	ret = ocfs2_extent_map_get_blocks(inode, iblock, &p_blkno,
465 					  &contig_blocks, &ext_flags);
466 	if (ret) {
467 		mlog(ML_ERROR, "get_blocks() failed iblock=%llu\n",
468 		     (unsigned long long)iblock);
469 		ret = -EIO;
470 		goto bail;
471 	}
472 
473 	if (!ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)) && !p_blkno) {
474 		ocfs2_error(inode->i_sb,
475 			    "Inode %llu has a hole at block %llu\n",
476 			    (unsigned long long)OCFS2_I(inode)->ip_blkno,
477 			    (unsigned long long)iblock);
478 		ret = -EROFS;
479 		goto bail;
480 	}
481 
482 	/*
483 	 * get_more_blocks() expects us to describe a hole by clearing
484 	 * the mapped bit on bh_result().
485 	 *
486 	 * Consider an unwritten extent as a hole.
487 	 */
488 	if (p_blkno && !(ext_flags & OCFS2_EXT_UNWRITTEN))
489 		map_bh(bh_result, inode->i_sb, p_blkno);
490 	else {
491 		/*
492 		 * ocfs2_prepare_inode_for_write() should have caught
493 		 * the case where we'd be filling a hole and triggered
494 		 * a buffered write instead.
495 		 */
496 		if (create) {
497 			ret = -EIO;
498 			mlog_errno(ret);
499 			goto bail;
500 		}
501 
502 		clear_buffer_mapped(bh_result);
503 	}
504 
505 	/* make sure we don't map more than max_blocks blocks here as
506 	   that's all the kernel will handle at this point. */
507 	if (max_blocks < contig_blocks)
508 		contig_blocks = max_blocks;
509 	bh_result->b_size = contig_blocks << blocksize_bits;
510 bail:
511 	return ret;
512 }
513 
514 /*
515  * ocfs2_dio_end_io is called by the dio core when a dio is finished.  We're
516  * particularly interested in the aio/dio case.  Like the core uses
517  * i_alloc_sem, we use the rw_lock DLM lock to protect io on one node from
518  * truncation on another.
519  */
520 static void ocfs2_dio_end_io(struct kiocb *iocb,
521 			     loff_t offset,
522 			     ssize_t bytes,
523 			     void *private)
524 {
525 	struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
526 	int level;
527 
528 	/* this io's submitter should not have unlocked this before we could */
529 	BUG_ON(!ocfs2_iocb_is_rw_locked(iocb));
530 
531 	ocfs2_iocb_clear_rw_locked(iocb);
532 
533 	level = ocfs2_iocb_rw_locked_level(iocb);
534 	if (!level)
535 		up_read(&inode->i_alloc_sem);
536 	ocfs2_rw_unlock(inode, level);
537 }
538 
539 /*
540  * ocfs2_invalidatepage() and ocfs2_releasepage() are shamelessly stolen
541  * from ext3.  PageChecked() bits have been removed as OCFS2 does not
542  * do journalled data.
543  */
544 static void ocfs2_invalidatepage(struct page *page, unsigned long offset)
545 {
546 	journal_t *journal = OCFS2_SB(page->mapping->host->i_sb)->journal->j_journal;
547 
548 	journal_invalidatepage(journal, page, offset);
549 }
550 
551 static int ocfs2_releasepage(struct page *page, gfp_t wait)
552 {
553 	journal_t *journal = OCFS2_SB(page->mapping->host->i_sb)->journal->j_journal;
554 
555 	if (!page_has_buffers(page))
556 		return 0;
557 	return journal_try_to_free_buffers(journal, page, wait);
558 }
559 
560 static ssize_t ocfs2_direct_IO(int rw,
561 			       struct kiocb *iocb,
562 			       const struct iovec *iov,
563 			       loff_t offset,
564 			       unsigned long nr_segs)
565 {
566 	struct file *file = iocb->ki_filp;
567 	struct inode *inode = file->f_path.dentry->d_inode->i_mapping->host;
568 	int ret;
569 
570 	mlog_entry_void();
571 
572 	if (!ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb))) {
573 		/*
574 		 * We get PR data locks even for O_DIRECT.  This
575 		 * allows concurrent O_DIRECT I/O but doesn't let
576 		 * O_DIRECT with extending and buffered zeroing writes
577 		 * race.  If they did race then the buffered zeroing
578 		 * could be written back after the O_DIRECT I/O.  It's
579 		 * one thing to tell people not to mix buffered and
580 		 * O_DIRECT writes, but expecting them to understand
581 		 * that file extension is also an implicit buffered
582 		 * write is too much.  By getting the PR we force
583 		 * writeback of the buffered zeroing before
584 		 * proceeding.
585 		 */
586 		ret = ocfs2_data_lock(inode, 0);
587 		if (ret < 0) {
588 			mlog_errno(ret);
589 			goto out;
590 		}
591 		ocfs2_data_unlock(inode, 0);
592 	}
593 
594 	ret = blockdev_direct_IO_no_locking(rw, iocb, inode,
595 					    inode->i_sb->s_bdev, iov, offset,
596 					    nr_segs,
597 					    ocfs2_direct_IO_get_blocks,
598 					    ocfs2_dio_end_io);
599 out:
600 	mlog_exit(ret);
601 	return ret;
602 }
603 
604 static void ocfs2_figure_cluster_boundaries(struct ocfs2_super *osb,
605 					    u32 cpos,
606 					    unsigned int *start,
607 					    unsigned int *end)
608 {
609 	unsigned int cluster_start = 0, cluster_end = PAGE_CACHE_SIZE;
610 
611 	if (unlikely(PAGE_CACHE_SHIFT > osb->s_clustersize_bits)) {
612 		unsigned int cpp;
613 
614 		cpp = 1 << (PAGE_CACHE_SHIFT - osb->s_clustersize_bits);
615 
616 		cluster_start = cpos % cpp;
617 		cluster_start = cluster_start << osb->s_clustersize_bits;
618 
619 		cluster_end = cluster_start + osb->s_clustersize;
620 	}
621 
622 	BUG_ON(cluster_start > PAGE_SIZE);
623 	BUG_ON(cluster_end > PAGE_SIZE);
624 
625 	if (start)
626 		*start = cluster_start;
627 	if (end)
628 		*end = cluster_end;
629 }
630 
631 /*
632  * 'from' and 'to' are the region in the page to avoid zeroing.
633  *
634  * If pagesize > clustersize, this function will avoid zeroing outside
635  * of the cluster boundary.
636  *
637  * from == to == 0 is code for "zero the entire cluster region"
638  */
639 static void ocfs2_clear_page_regions(struct page *page,
640 				     struct ocfs2_super *osb, u32 cpos,
641 				     unsigned from, unsigned to)
642 {
643 	void *kaddr;
644 	unsigned int cluster_start, cluster_end;
645 
646 	ocfs2_figure_cluster_boundaries(osb, cpos, &cluster_start, &cluster_end);
647 
648 	kaddr = kmap_atomic(page, KM_USER0);
649 
650 	if (from || to) {
651 		if (from > cluster_start)
652 			memset(kaddr + cluster_start, 0, from - cluster_start);
653 		if (to < cluster_end)
654 			memset(kaddr + to, 0, cluster_end - to);
655 	} else {
656 		memset(kaddr + cluster_start, 0, cluster_end - cluster_start);
657 	}
658 
659 	kunmap_atomic(kaddr, KM_USER0);
660 }
661 
662 /*
663  * Some of this taken from block_prepare_write(). We already have our
664  * mapping by now though, and the entire write will be allocating or
665  * it won't, so not much need to use BH_New.
666  *
667  * This will also skip zeroing, which is handled externally.
668  */
669 int ocfs2_map_page_blocks(struct page *page, u64 *p_blkno,
670 			  struct inode *inode, unsigned int from,
671 			  unsigned int to, int new)
672 {
673 	int ret = 0;
674 	struct buffer_head *head, *bh, *wait[2], **wait_bh = wait;
675 	unsigned int block_end, block_start;
676 	unsigned int bsize = 1 << inode->i_blkbits;
677 
678 	if (!page_has_buffers(page))
679 		create_empty_buffers(page, bsize, 0);
680 
681 	head = page_buffers(page);
682 	for (bh = head, block_start = 0; bh != head || !block_start;
683 	     bh = bh->b_this_page, block_start += bsize) {
684 		block_end = block_start + bsize;
685 
686 		/*
687 		 * Ignore blocks outside of our i/o range -
688 		 * they may belong to unallocated clusters.
689 		 */
690 		if (block_start >= to || block_end <= from) {
691 			if (PageUptodate(page))
692 				set_buffer_uptodate(bh);
693 			continue;
694 		}
695 
696 		/*
697 		 * For an allocating write with cluster size >= page
698 		 * size, we always write the entire page.
699 		 */
700 
701 		if (buffer_new(bh))
702 			clear_buffer_new(bh);
703 
704 		if (!buffer_mapped(bh)) {
705 			map_bh(bh, inode->i_sb, *p_blkno);
706 			unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
707 		}
708 
709 		if (PageUptodate(page)) {
710 			if (!buffer_uptodate(bh))
711 				set_buffer_uptodate(bh);
712 		} else if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
713 		     (block_start < from || block_end > to)) {
714 			ll_rw_block(READ, 1, &bh);
715 			*wait_bh++=bh;
716 		}
717 
718 		*p_blkno = *p_blkno + 1;
719 	}
720 
721 	/*
722 	 * If we issued read requests - let them complete.
723 	 */
724 	while(wait_bh > wait) {
725 		wait_on_buffer(*--wait_bh);
726 		if (!buffer_uptodate(*wait_bh))
727 			ret = -EIO;
728 	}
729 
730 	if (ret == 0 || !new)
731 		return ret;
732 
733 	/*
734 	 * If we get -EIO above, zero out any newly allocated blocks
735 	 * to avoid exposing stale data.
736 	 */
737 	bh = head;
738 	block_start = 0;
739 	do {
740 		void *kaddr;
741 
742 		block_end = block_start + bsize;
743 		if (block_end <= from)
744 			goto next_bh;
745 		if (block_start >= to)
746 			break;
747 
748 		kaddr = kmap_atomic(page, KM_USER0);
749 		memset(kaddr+block_start, 0, bh->b_size);
750 		flush_dcache_page(page);
751 		kunmap_atomic(kaddr, KM_USER0);
752 		set_buffer_uptodate(bh);
753 		mark_buffer_dirty(bh);
754 
755 next_bh:
756 		block_start = block_end;
757 		bh = bh->b_this_page;
758 	} while (bh != head);
759 
760 	return ret;
761 }
762 
763 /*
764  * This will copy user data from the buffer page in the splice
765  * context.
766  *
767  * For now, we ignore SPLICE_F_MOVE as that would require some extra
768  * communication out all the way to ocfs2_write().
769  */
770 int ocfs2_map_and_write_splice_data(struct inode *inode,
771 				  struct ocfs2_write_ctxt *wc, u64 *p_blkno,
772 				  unsigned int *ret_from, unsigned int *ret_to)
773 {
774 	int ret;
775 	unsigned int to, from, cluster_start, cluster_end;
776 	char *src, *dst;
777 	struct ocfs2_splice_write_priv *sp = wc->w_private;
778 	struct pipe_buffer *buf = sp->s_buf;
779 	unsigned long bytes, src_from;
780 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
781 
782 	ocfs2_figure_cluster_boundaries(osb, wc->w_cpos, &cluster_start,
783 					&cluster_end);
784 
785 	from = sp->s_offset;
786 	src_from = sp->s_buf_offset;
787 	bytes = wc->w_count;
788 
789 	if (wc->w_large_pages) {
790 		/*
791 		 * For cluster size < page size, we have to
792 		 * calculate pos within the cluster and obey
793 		 * the rightmost boundary.
794 		 */
795 		bytes = min(bytes, (unsigned long)(osb->s_clustersize
796 				   - (wc->w_pos & (osb->s_clustersize - 1))));
797 	}
798 	to = from + bytes;
799 
800 	if (wc->w_this_page_new)
801 		ret = ocfs2_map_page_blocks(wc->w_this_page, p_blkno, inode,
802 					    cluster_start, cluster_end, 1);
803 	else
804 		ret = ocfs2_map_page_blocks(wc->w_this_page, p_blkno, inode,
805 					    from, to, 0);
806 	if (ret) {
807 		mlog_errno(ret);
808 		goto out;
809 	}
810 
811 	BUG_ON(from > PAGE_CACHE_SIZE);
812 	BUG_ON(to > PAGE_CACHE_SIZE);
813 	BUG_ON(from > osb->s_clustersize);
814 	BUG_ON(to > osb->s_clustersize);
815 
816 	src = buf->ops->map(sp->s_pipe, buf, 1);
817 	dst = kmap_atomic(wc->w_this_page, KM_USER1);
818 	memcpy(dst + from, src + src_from, bytes);
819 	kunmap_atomic(wc->w_this_page, KM_USER1);
820 	buf->ops->unmap(sp->s_pipe, buf, src);
821 
822 	wc->w_finished_copy = 1;
823 
824 	*ret_from = from;
825 	*ret_to = to;
826 out:
827 
828 	return bytes ? (unsigned int)bytes : ret;
829 }
830 
831 /*
832  * This will copy user data from the iovec in the buffered write
833  * context.
834  */
835 int ocfs2_map_and_write_user_data(struct inode *inode,
836 				  struct ocfs2_write_ctxt *wc, u64 *p_blkno,
837 				  unsigned int *ret_from, unsigned int *ret_to)
838 {
839 	int ret;
840 	unsigned int to, from, cluster_start, cluster_end;
841 	unsigned long bytes, src_from;
842 	char *dst;
843 	struct ocfs2_buffered_write_priv *bp = wc->w_private;
844 	const struct iovec *cur_iov = bp->b_cur_iov;
845 	char __user *buf;
846 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
847 
848 	ocfs2_figure_cluster_boundaries(osb, wc->w_cpos, &cluster_start,
849 					&cluster_end);
850 
851 	buf = cur_iov->iov_base + bp->b_cur_off;
852 	src_from = (unsigned long)buf & ~PAGE_CACHE_MASK;
853 
854 	from = wc->w_pos & (PAGE_CACHE_SIZE - 1);
855 
856 	/*
857 	 * This is a lot of comparisons, but it reads quite
858 	 * easily, which is important here.
859 	 */
860 	/* Stay within the src page */
861 	bytes = PAGE_SIZE - src_from;
862 	/* Stay within the vector */
863 	bytes = min(bytes,
864 		    (unsigned long)(cur_iov->iov_len - bp->b_cur_off));
865 	/* Stay within count */
866 	bytes = min(bytes, (unsigned long)wc->w_count);
867 	/*
868 	 * For clustersize > page size, just stay within
869 	 * target page, otherwise we have to calculate pos
870 	 * within the cluster and obey the rightmost
871 	 * boundary.
872 	 */
873 	if (wc->w_large_pages) {
874 		/*
875 		 * For cluster size < page size, we have to
876 		 * calculate pos within the cluster and obey
877 		 * the rightmost boundary.
878 		 */
879 		bytes = min(bytes, (unsigned long)(osb->s_clustersize
880 				   - (wc->w_pos & (osb->s_clustersize - 1))));
881 	} else {
882 		/*
883 		 * cluster size > page size is the most common
884 		 * case - we just stay within the target page
885 		 * boundary.
886 		 */
887 		bytes = min(bytes, PAGE_CACHE_SIZE - from);
888 	}
889 
890 	to = from + bytes;
891 
892 	if (wc->w_this_page_new)
893 		ret = ocfs2_map_page_blocks(wc->w_this_page, p_blkno, inode,
894 					    cluster_start, cluster_end, 1);
895 	else
896 		ret = ocfs2_map_page_blocks(wc->w_this_page, p_blkno, inode,
897 					    from, to, 0);
898 	if (ret) {
899 		mlog_errno(ret);
900 		goto out;
901 	}
902 
903 	BUG_ON(from > PAGE_CACHE_SIZE);
904 	BUG_ON(to > PAGE_CACHE_SIZE);
905 	BUG_ON(from > osb->s_clustersize);
906 	BUG_ON(to > osb->s_clustersize);
907 
908 	dst = kmap(wc->w_this_page);
909 	memcpy(dst + from, bp->b_src_buf + src_from, bytes);
910 	kunmap(wc->w_this_page);
911 
912 	/*
913 	 * XXX: This is slow, but simple. The caller of
914 	 * ocfs2_buffered_write_cluster() is responsible for
915 	 * passing through the iovecs, so it's difficult to
916 	 * predict what our next step is in here after our
917 	 * initial write. A future version should be pushing
918 	 * that iovec manipulation further down.
919 	 *
920 	 * By setting this, we indicate that a copy from user
921 	 * data was done, and subsequent calls for this
922 	 * cluster will skip copying more data.
923 	 */
924 	wc->w_finished_copy = 1;
925 
926 	*ret_from = from;
927 	*ret_to = to;
928 out:
929 
930 	return bytes ? (unsigned int)bytes : ret;
931 }
932 
933 /*
934  * Map, fill and write a page to disk.
935  *
936  * The work of copying data is done via callback.  Newly allocated
937  * pages which don't take user data will be zero'd (set 'new' to
938  * indicate an allocating write)
939  *
940  * Returns a negative error code or the number of bytes copied into
941  * the page.
942  */
943 static int ocfs2_write_data_page(struct inode *inode, handle_t *handle,
944 				 u64 *p_blkno, struct page *page,
945 				 struct ocfs2_write_ctxt *wc, int new)
946 {
947 	int ret, copied = 0;
948 	unsigned int from = 0, to = 0;
949 	unsigned int cluster_start, cluster_end;
950 	unsigned int zero_from = 0, zero_to = 0;
951 
952 	ocfs2_figure_cluster_boundaries(OCFS2_SB(inode->i_sb), wc->w_cpos,
953 					&cluster_start, &cluster_end);
954 
955 	if ((wc->w_pos >> PAGE_CACHE_SHIFT) == page->index
956 	    && !wc->w_finished_copy) {
957 
958 		wc->w_this_page = page;
959 		wc->w_this_page_new = new;
960 		ret = wc->w_write_data_page(inode, wc, p_blkno, &from, &to);
961 		if (ret < 0) {
962 			mlog_errno(ret);
963 			goto out;
964 		}
965 
966 		copied = ret;
967 
968 		zero_from = from;
969 		zero_to = to;
970 		if (new) {
971 			from = cluster_start;
972 			to = cluster_end;
973 		}
974 	} else {
975 		/*
976 		 * If we haven't allocated the new page yet, we
977 		 * shouldn't be writing it out without copying user
978 		 * data. This is likely a math error from the caller.
979 		 */
980 		BUG_ON(!new);
981 
982 		from = cluster_start;
983 		to = cluster_end;
984 
985 		ret = ocfs2_map_page_blocks(page, p_blkno, inode,
986 					    cluster_start, cluster_end, 1);
987 		if (ret) {
988 			mlog_errno(ret);
989 			goto out;
990 		}
991 	}
992 
993 	/*
994 	 * Parts of newly allocated pages need to be zero'd.
995 	 *
996 	 * Above, we have also rewritten 'to' and 'from' - as far as
997 	 * the rest of the function is concerned, the entire cluster
998 	 * range inside of a page needs to be written.
999 	 *
1000 	 * We can skip this if the page is up to date - it's already
1001 	 * been zero'd from being read in as a hole.
1002 	 */
1003 	if (new && !PageUptodate(page))
1004 		ocfs2_clear_page_regions(page, OCFS2_SB(inode->i_sb),
1005 					 wc->w_cpos, zero_from, zero_to);
1006 
1007 	flush_dcache_page(page);
1008 
1009 	if (ocfs2_should_order_data(inode)) {
1010 		ret = walk_page_buffers(handle,
1011 					page_buffers(page),
1012 					from, to, NULL,
1013 					ocfs2_journal_dirty_data);
1014 		if (ret < 0)
1015 			mlog_errno(ret);
1016 	}
1017 
1018 	/*
1019 	 * We don't use generic_commit_write() because we need to
1020 	 * handle our own i_size update.
1021 	 */
1022 	ret = block_commit_write(page, from, to);
1023 	if (ret)
1024 		mlog_errno(ret);
1025 out:
1026 
1027 	return copied ? copied : ret;
1028 }
1029 
1030 /*
1031  * Do the actual write of some data into an inode. Optionally allocate
1032  * in order to fulfill the write.
1033  *
1034  * cpos is the logical cluster offset within the file to write at
1035  *
1036  * 'phys' is the physical mapping of that offset. a 'phys' value of
1037  * zero indicates that allocation is required. In this case, data_ac
1038  * and meta_ac should be valid (meta_ac can be null if metadata
1039  * allocation isn't required).
1040  */
1041 static ssize_t ocfs2_write(struct file *file, u32 phys, handle_t *handle,
1042 			   struct buffer_head *di_bh,
1043 			   struct ocfs2_alloc_context *data_ac,
1044 			   struct ocfs2_alloc_context *meta_ac,
1045 			   struct ocfs2_write_ctxt *wc)
1046 {
1047 	int ret, i, numpages = 1, new;
1048 	unsigned int copied = 0;
1049 	u32 tmp_pos;
1050 	u64 v_blkno, p_blkno;
1051 	struct address_space *mapping = file->f_mapping;
1052 	struct inode *inode = mapping->host;
1053 	unsigned long index, start;
1054 	struct page **cpages;
1055 
1056 	new = phys == 0 ? 1 : 0;
1057 
1058 	/*
1059 	 * Figure out how many pages we'll be manipulating here. For
1060 	 * non allocating write, we just change the one
1061 	 * page. Otherwise, we'll need a whole clusters worth.
1062 	 */
1063 	if (new)
1064 		numpages = ocfs2_pages_per_cluster(inode->i_sb);
1065 
1066 	cpages = kzalloc(sizeof(*cpages) * numpages, GFP_NOFS);
1067 	if (!cpages) {
1068 		ret = -ENOMEM;
1069 		mlog_errno(ret);
1070 		return ret;
1071 	}
1072 
1073 	/*
1074 	 * Fill our page array first. That way we've grabbed enough so
1075 	 * that we can zero and flush if we error after adding the
1076 	 * extent.
1077 	 */
1078 	if (new) {
1079 		start = ocfs2_align_clusters_to_page_index(inode->i_sb,
1080 							   wc->w_cpos);
1081 		v_blkno = ocfs2_clusters_to_blocks(inode->i_sb, wc->w_cpos);
1082 	} else {
1083 		start = wc->w_pos >> PAGE_CACHE_SHIFT;
1084 		v_blkno = wc->w_pos >> inode->i_sb->s_blocksize_bits;
1085 	}
1086 
1087 	for(i = 0; i < numpages; i++) {
1088 		index = start + i;
1089 
1090 		cpages[i] = find_or_create_page(mapping, index, GFP_NOFS);
1091 		if (!cpages[i]) {
1092 			ret = -ENOMEM;
1093 			mlog_errno(ret);
1094 			goto out;
1095 		}
1096 	}
1097 
1098 	if (new) {
1099 		/*
1100 		 * This is safe to call with the page locks - it won't take
1101 		 * any additional semaphores or cluster locks.
1102 		 */
1103 		tmp_pos = wc->w_cpos;
1104 		ret = ocfs2_do_extend_allocation(OCFS2_SB(inode->i_sb), inode,
1105 						 &tmp_pos, 1, di_bh, handle,
1106 						 data_ac, meta_ac, NULL);
1107 		/*
1108 		 * This shouldn't happen because we must have already
1109 		 * calculated the correct meta data allocation required. The
1110 		 * internal tree allocation code should know how to increase
1111 		 * transaction credits itself.
1112 		 *
1113 		 * If need be, we could handle -EAGAIN for a
1114 		 * RESTART_TRANS here.
1115 		 */
1116 		mlog_bug_on_msg(ret == -EAGAIN,
1117 				"Inode %llu: EAGAIN return during allocation.\n",
1118 				(unsigned long long)OCFS2_I(inode)->ip_blkno);
1119 		if (ret < 0) {
1120 			mlog_errno(ret);
1121 			goto out;
1122 		}
1123 	}
1124 
1125 	ret = ocfs2_extent_map_get_blocks(inode, v_blkno, &p_blkno, NULL,
1126 					  NULL);
1127 	if (ret < 0) {
1128 
1129 		/*
1130 		 * XXX: Should we go readonly here?
1131 		 */
1132 
1133 		mlog_errno(ret);
1134 		goto out;
1135 	}
1136 
1137 	BUG_ON(p_blkno == 0);
1138 
1139 	for(i = 0; i < numpages; i++) {
1140 		ret = ocfs2_write_data_page(inode, handle, &p_blkno, cpages[i],
1141 					    wc, new);
1142 		if (ret < 0) {
1143 			mlog_errno(ret);
1144 			goto out;
1145 		}
1146 
1147 		copied += ret;
1148 	}
1149 
1150 out:
1151 	for(i = 0; i < numpages; i++) {
1152 		unlock_page(cpages[i]);
1153 		mark_page_accessed(cpages[i]);
1154 		page_cache_release(cpages[i]);
1155 	}
1156 	kfree(cpages);
1157 
1158 	return copied ? copied : ret;
1159 }
1160 
1161 static void ocfs2_write_ctxt_init(struct ocfs2_write_ctxt *wc,
1162 				  struct ocfs2_super *osb, loff_t pos,
1163 				  size_t count, ocfs2_page_writer *cb,
1164 				  void *cb_priv)
1165 {
1166 	wc->w_count = count;
1167 	wc->w_pos = pos;
1168 	wc->w_cpos = wc->w_pos >> osb->s_clustersize_bits;
1169 	wc->w_finished_copy = 0;
1170 
1171 	if (unlikely(PAGE_CACHE_SHIFT > osb->s_clustersize_bits))
1172 		wc->w_large_pages = 1;
1173 	else
1174 		wc->w_large_pages = 0;
1175 
1176 	wc->w_write_data_page = cb;
1177 	wc->w_private = cb_priv;
1178 }
1179 
1180 /*
1181  * Write a cluster to an inode. The cluster may not be allocated yet,
1182  * in which case it will be. This only exists for buffered writes -
1183  * O_DIRECT takes a more "traditional" path through the kernel.
1184  *
1185  * The caller is responsible for incrementing pos, written counts, etc
1186  *
1187  * For file systems that don't support sparse files, pre-allocation
1188  * and page zeroing up until cpos should be done prior to this
1189  * function call.
1190  *
1191  * Callers should be holding i_sem, and the rw cluster lock.
1192  *
1193  * Returns the number of user bytes written, or less than zero for
1194  * error.
1195  */
1196 ssize_t ocfs2_buffered_write_cluster(struct file *file, loff_t pos,
1197 				     size_t count, ocfs2_page_writer *actor,
1198 				     void *priv)
1199 {
1200 	int ret, credits = OCFS2_INODE_UPDATE_CREDITS;
1201 	ssize_t written = 0;
1202 	u32 phys;
1203 	struct inode *inode = file->f_mapping->host;
1204 	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
1205 	struct buffer_head *di_bh = NULL;
1206 	struct ocfs2_dinode *di;
1207 	struct ocfs2_alloc_context *data_ac = NULL;
1208 	struct ocfs2_alloc_context *meta_ac = NULL;
1209 	handle_t *handle;
1210 	struct ocfs2_write_ctxt wc;
1211 
1212 	ocfs2_write_ctxt_init(&wc, osb, pos, count, actor, priv);
1213 
1214 	ret = ocfs2_meta_lock(inode, &di_bh, 1);
1215 	if (ret) {
1216 		mlog_errno(ret);
1217 		goto out;
1218 	}
1219 	di = (struct ocfs2_dinode *)di_bh->b_data;
1220 
1221 	/*
1222 	 * Take alloc sem here to prevent concurrent lookups. That way
1223 	 * the mapping, zeroing and tree manipulation within
1224 	 * ocfs2_write() will be safe against ->readpage(). This
1225 	 * should also serve to lock out allocation from a shared
1226 	 * writeable region.
1227 	 */
1228 	down_write(&OCFS2_I(inode)->ip_alloc_sem);
1229 
1230 	ret = ocfs2_get_clusters(inode, wc.w_cpos, &phys, NULL, NULL);
1231 	if (ret) {
1232 		mlog_errno(ret);
1233 		goto out_meta;
1234 	}
1235 
1236 	/* phys == 0 means that allocation is required. */
1237 	if (phys == 0) {
1238 		ret = ocfs2_lock_allocators(inode, di, 1, &data_ac, &meta_ac);
1239 		if (ret) {
1240 			mlog_errno(ret);
1241 			goto out_meta;
1242 		}
1243 
1244 		credits = ocfs2_calc_extend_credits(inode->i_sb, di, 1);
1245 	}
1246 
1247 	ret = ocfs2_data_lock(inode, 1);
1248 	if (ret) {
1249 		mlog_errno(ret);
1250 		goto out_meta;
1251 	}
1252 
1253 	handle = ocfs2_start_trans(osb, credits);
1254 	if (IS_ERR(handle)) {
1255 		ret = PTR_ERR(handle);
1256 		mlog_errno(ret);
1257 		goto out_data;
1258 	}
1259 
1260 	written = ocfs2_write(file, phys, handle, di_bh, data_ac,
1261 			      meta_ac, &wc);
1262 	if (written < 0) {
1263 		ret = written;
1264 		mlog_errno(ret);
1265 		goto out_commit;
1266 	}
1267 
1268 	ret = ocfs2_journal_access(handle, inode, di_bh,
1269 				   OCFS2_JOURNAL_ACCESS_WRITE);
1270 	if (ret) {
1271 		mlog_errno(ret);
1272 		goto out_commit;
1273 	}
1274 
1275 	pos += written;
1276 	if (pos > inode->i_size) {
1277 		i_size_write(inode, pos);
1278 		mark_inode_dirty(inode);
1279 	}
1280 	inode->i_blocks = ocfs2_inode_sector_count(inode);
1281 	di->i_size = cpu_to_le64((u64)i_size_read(inode));
1282 	inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1283 	di->i_mtime = di->i_ctime = cpu_to_le64(inode->i_mtime.tv_sec);
1284 	di->i_mtime_nsec = di->i_ctime_nsec = cpu_to_le32(inode->i_mtime.tv_nsec);
1285 
1286 	ret = ocfs2_journal_dirty(handle, di_bh);
1287 	if (ret)
1288 		mlog_errno(ret);
1289 
1290 out_commit:
1291 	ocfs2_commit_trans(osb, handle);
1292 
1293 out_data:
1294 	ocfs2_data_unlock(inode, 1);
1295 
1296 out_meta:
1297 	up_write(&OCFS2_I(inode)->ip_alloc_sem);
1298 	ocfs2_meta_unlock(inode, 1);
1299 
1300 out:
1301 	brelse(di_bh);
1302 	if (data_ac)
1303 		ocfs2_free_alloc_context(data_ac);
1304 	if (meta_ac)
1305 		ocfs2_free_alloc_context(meta_ac);
1306 
1307 	return written ? written : ret;
1308 }
1309 
1310 const struct address_space_operations ocfs2_aops = {
1311 	.readpage	= ocfs2_readpage,
1312 	.writepage	= ocfs2_writepage,
1313 	.bmap		= ocfs2_bmap,
1314 	.sync_page	= block_sync_page,
1315 	.direct_IO	= ocfs2_direct_IO,
1316 	.invalidatepage	= ocfs2_invalidatepage,
1317 	.releasepage	= ocfs2_releasepage,
1318 	.migratepage	= buffer_migrate_page,
1319 };
1320