xref: /openbmc/linux/fs/gfs2/aops.c (revision 70c11ba8)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
4  * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
5  */
6 
7 #include <linux/sched.h>
8 #include <linux/slab.h>
9 #include <linux/spinlock.h>
10 #include <linux/completion.h>
11 #include <linux/buffer_head.h>
12 #include <linux/pagemap.h>
13 #include <linux/pagevec.h>
14 #include <linux/mpage.h>
15 #include <linux/fs.h>
16 #include <linux/writeback.h>
17 #include <linux/swap.h>
18 #include <linux/gfs2_ondisk.h>
19 #include <linux/backing-dev.h>
20 #include <linux/uio.h>
21 #include <trace/events/writeback.h>
22 #include <linux/sched/signal.h>
23 
24 #include "gfs2.h"
25 #include "incore.h"
26 #include "bmap.h"
27 #include "glock.h"
28 #include "inode.h"
29 #include "log.h"
30 #include "meta_io.h"
31 #include "quota.h"
32 #include "trans.h"
33 #include "rgrp.h"
34 #include "super.h"
35 #include "util.h"
36 #include "glops.h"
37 #include "aops.h"
38 
39 
40 void gfs2_page_add_databufs(struct gfs2_inode *ip, struct page *page,
41 			    unsigned int from, unsigned int len)
42 {
43 	struct buffer_head *head = page_buffers(page);
44 	unsigned int bsize = head->b_size;
45 	struct buffer_head *bh;
46 	unsigned int to = from + len;
47 	unsigned int start, end;
48 
49 	for (bh = head, start = 0; bh != head || !start;
50 	     bh = bh->b_this_page, start = end) {
51 		end = start + bsize;
52 		if (end <= from)
53 			continue;
54 		if (start >= to)
55 			break;
56 		set_buffer_uptodate(bh);
57 		gfs2_trans_add_data(ip->i_gl, bh);
58 	}
59 }
60 
61 /**
62  * gfs2_get_block_noalloc - Fills in a buffer head with details about a block
63  * @inode: The inode
64  * @lblock: The block number to look up
65  * @bh_result: The buffer head to return the result in
66  * @create: Non-zero if we may add block to the file
67  *
68  * Returns: errno
69  */
70 
71 static int gfs2_get_block_noalloc(struct inode *inode, sector_t lblock,
72 				  struct buffer_head *bh_result, int create)
73 {
74 	int error;
75 
76 	error = gfs2_block_map(inode, lblock, bh_result, 0);
77 	if (error)
78 		return error;
79 	if (!buffer_mapped(bh_result))
80 		return -ENODATA;
81 	return 0;
82 }
83 
84 /**
85  * gfs2_writepage - Write page for writeback mappings
86  * @page: The page
87  * @wbc: The writeback control
88  */
89 static int gfs2_writepage(struct page *page, struct writeback_control *wbc)
90 {
91 	struct inode *inode = page->mapping->host;
92 	struct gfs2_inode *ip = GFS2_I(inode);
93 	struct gfs2_sbd *sdp = GFS2_SB(inode);
94 	struct iomap_writepage_ctx wpc = { };
95 
96 	if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
97 		goto out;
98 	if (current->journal_info)
99 		goto redirty;
100 	return iomap_writepage(page, wbc, &wpc, &gfs2_writeback_ops);
101 
102 redirty:
103 	redirty_page_for_writepage(wbc, page);
104 out:
105 	unlock_page(page);
106 	return 0;
107 }
108 
109 /**
110  * gfs2_write_jdata_page - gfs2 jdata-specific version of block_write_full_page
111  * @page: The page to write
112  * @wbc: The writeback control
113  *
114  * This is the same as calling block_write_full_page, but it also
115  * writes pages outside of i_size
116  */
117 static int gfs2_write_jdata_page(struct page *page,
118 				 struct writeback_control *wbc)
119 {
120 	struct inode * const inode = page->mapping->host;
121 	loff_t i_size = i_size_read(inode);
122 	const pgoff_t end_index = i_size >> PAGE_SHIFT;
123 	unsigned offset;
124 
125 	/*
126 	 * The page straddles i_size.  It must be zeroed out on each and every
127 	 * writepage invocation because it may be mmapped.  "A file is mapped
128 	 * in multiples of the page size.  For a file that is not a multiple of
129 	 * the  page size, the remaining memory is zeroed when mapped, and
130 	 * writes to that region are not written out to the file."
131 	 */
132 	offset = i_size & (PAGE_SIZE - 1);
133 	if (page->index == end_index && offset)
134 		zero_user_segment(page, offset, PAGE_SIZE);
135 
136 	return __block_write_full_page(inode, page, gfs2_get_block_noalloc, wbc,
137 				       end_buffer_async_write);
138 }
139 
140 /**
141  * __gfs2_jdata_writepage - The core of jdata writepage
142  * @page: The page to write
143  * @wbc: The writeback control
144  *
145  * This is shared between writepage and writepages and implements the
146  * core of the writepage operation. If a transaction is required then
147  * PageChecked will have been set and the transaction will have
148  * already been started before this is called.
149  */
150 
151 static int __gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
152 {
153 	struct inode *inode = page->mapping->host;
154 	struct gfs2_inode *ip = GFS2_I(inode);
155 	struct gfs2_sbd *sdp = GFS2_SB(inode);
156 
157 	if (PageChecked(page)) {
158 		ClearPageChecked(page);
159 		if (!page_has_buffers(page)) {
160 			create_empty_buffers(page, inode->i_sb->s_blocksize,
161 					     BIT(BH_Dirty)|BIT(BH_Uptodate));
162 		}
163 		gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize);
164 	}
165 	return gfs2_write_jdata_page(page, wbc);
166 }
167 
168 /**
169  * gfs2_jdata_writepage - Write complete page
170  * @page: Page to write
171  * @wbc: The writeback control
172  *
173  * Returns: errno
174  *
175  */
176 
177 static int gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
178 {
179 	struct inode *inode = page->mapping->host;
180 	struct gfs2_inode *ip = GFS2_I(inode);
181 	struct gfs2_sbd *sdp = GFS2_SB(inode);
182 
183 	if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
184 		goto out;
185 	if (PageChecked(page) || current->journal_info)
186 		goto out_ignore;
187 	return __gfs2_jdata_writepage(page, wbc);
188 
189 out_ignore:
190 	redirty_page_for_writepage(wbc, page);
191 out:
192 	unlock_page(page);
193 	return 0;
194 }
195 
196 /**
197  * gfs2_writepages - Write a bunch of dirty pages back to disk
198  * @mapping: The mapping to write
199  * @wbc: Write-back control
200  *
201  * Used for both ordered and writeback modes.
202  */
203 static int gfs2_writepages(struct address_space *mapping,
204 			   struct writeback_control *wbc)
205 {
206 	struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
207 	struct iomap_writepage_ctx wpc = { };
208 	int ret;
209 
210 	/*
211 	 * Even if we didn't write any pages here, we might still be holding
212 	 * dirty pages in the ail. We forcibly flush the ail because we don't
213 	 * want balance_dirty_pages() to loop indefinitely trying to write out
214 	 * pages held in the ail that it can't find.
215 	 */
216 	ret = iomap_writepages(mapping, wbc, &wpc, &gfs2_writeback_ops);
217 	if (ret == 0)
218 		set_bit(SDF_FORCE_AIL_FLUSH, &sdp->sd_flags);
219 	return ret;
220 }
221 
222 /**
223  * gfs2_write_jdata_pagevec - Write back a pagevec's worth of pages
224  * @mapping: The mapping
225  * @wbc: The writeback control
226  * @pvec: The vector of pages
227  * @nr_pages: The number of pages to write
228  * @done_index: Page index
229  *
230  * Returns: non-zero if loop should terminate, zero otherwise
231  */
232 
233 static int gfs2_write_jdata_pagevec(struct address_space *mapping,
234 				    struct writeback_control *wbc,
235 				    struct pagevec *pvec,
236 				    int nr_pages,
237 				    pgoff_t *done_index)
238 {
239 	struct inode *inode = mapping->host;
240 	struct gfs2_sbd *sdp = GFS2_SB(inode);
241 	unsigned nrblocks = nr_pages * (PAGE_SIZE >> inode->i_blkbits);
242 	int i;
243 	int ret;
244 
245 	ret = gfs2_trans_begin(sdp, nrblocks, nrblocks);
246 	if (ret < 0)
247 		return ret;
248 
249 	for(i = 0; i < nr_pages; i++) {
250 		struct page *page = pvec->pages[i];
251 
252 		*done_index = page->index;
253 
254 		lock_page(page);
255 
256 		if (unlikely(page->mapping != mapping)) {
257 continue_unlock:
258 			unlock_page(page);
259 			continue;
260 		}
261 
262 		if (!PageDirty(page)) {
263 			/* someone wrote it for us */
264 			goto continue_unlock;
265 		}
266 
267 		if (PageWriteback(page)) {
268 			if (wbc->sync_mode != WB_SYNC_NONE)
269 				wait_on_page_writeback(page);
270 			else
271 				goto continue_unlock;
272 		}
273 
274 		BUG_ON(PageWriteback(page));
275 		if (!clear_page_dirty_for_io(page))
276 			goto continue_unlock;
277 
278 		trace_wbc_writepage(wbc, inode_to_bdi(inode));
279 
280 		ret = __gfs2_jdata_writepage(page, wbc);
281 		if (unlikely(ret)) {
282 			if (ret == AOP_WRITEPAGE_ACTIVATE) {
283 				unlock_page(page);
284 				ret = 0;
285 			} else {
286 
287 				/*
288 				 * done_index is set past this page,
289 				 * so media errors will not choke
290 				 * background writeout for the entire
291 				 * file. This has consequences for
292 				 * range_cyclic semantics (ie. it may
293 				 * not be suitable for data integrity
294 				 * writeout).
295 				 */
296 				*done_index = page->index + 1;
297 				ret = 1;
298 				break;
299 			}
300 		}
301 
302 		/*
303 		 * We stop writing back only if we are not doing
304 		 * integrity sync. In case of integrity sync we have to
305 		 * keep going until we have written all the pages
306 		 * we tagged for writeback prior to entering this loop.
307 		 */
308 		if (--wbc->nr_to_write <= 0 && wbc->sync_mode == WB_SYNC_NONE) {
309 			ret = 1;
310 			break;
311 		}
312 
313 	}
314 	gfs2_trans_end(sdp);
315 	return ret;
316 }
317 
318 /**
319  * gfs2_write_cache_jdata - Like write_cache_pages but different
320  * @mapping: The mapping to write
321  * @wbc: The writeback control
322  *
323  * The reason that we use our own function here is that we need to
324  * start transactions before we grab page locks. This allows us
325  * to get the ordering right.
326  */
327 
328 static int gfs2_write_cache_jdata(struct address_space *mapping,
329 				  struct writeback_control *wbc)
330 {
331 	int ret = 0;
332 	int done = 0;
333 	struct pagevec pvec;
334 	int nr_pages;
335 	pgoff_t writeback_index;
336 	pgoff_t index;
337 	pgoff_t end;
338 	pgoff_t done_index;
339 	int cycled;
340 	int range_whole = 0;
341 	xa_mark_t tag;
342 
343 	pagevec_init(&pvec);
344 	if (wbc->range_cyclic) {
345 		writeback_index = mapping->writeback_index; /* prev offset */
346 		index = writeback_index;
347 		if (index == 0)
348 			cycled = 1;
349 		else
350 			cycled = 0;
351 		end = -1;
352 	} else {
353 		index = wbc->range_start >> PAGE_SHIFT;
354 		end = wbc->range_end >> PAGE_SHIFT;
355 		if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
356 			range_whole = 1;
357 		cycled = 1; /* ignore range_cyclic tests */
358 	}
359 	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
360 		tag = PAGECACHE_TAG_TOWRITE;
361 	else
362 		tag = PAGECACHE_TAG_DIRTY;
363 
364 retry:
365 	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
366 		tag_pages_for_writeback(mapping, index, end);
367 	done_index = index;
368 	while (!done && (index <= end)) {
369 		nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index, end,
370 				tag);
371 		if (nr_pages == 0)
372 			break;
373 
374 		ret = gfs2_write_jdata_pagevec(mapping, wbc, &pvec, nr_pages, &done_index);
375 		if (ret)
376 			done = 1;
377 		if (ret > 0)
378 			ret = 0;
379 		pagevec_release(&pvec);
380 		cond_resched();
381 	}
382 
383 	if (!cycled && !done) {
384 		/*
385 		 * range_cyclic:
386 		 * We hit the last page and there is more work to be done: wrap
387 		 * back to the start of the file
388 		 */
389 		cycled = 1;
390 		index = 0;
391 		end = writeback_index - 1;
392 		goto retry;
393 	}
394 
395 	if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
396 		mapping->writeback_index = done_index;
397 
398 	return ret;
399 }
400 
401 
402 /**
403  * gfs2_jdata_writepages - Write a bunch of dirty pages back to disk
404  * @mapping: The mapping to write
405  * @wbc: The writeback control
406  *
407  */
408 
409 static int gfs2_jdata_writepages(struct address_space *mapping,
410 				 struct writeback_control *wbc)
411 {
412 	struct gfs2_inode *ip = GFS2_I(mapping->host);
413 	struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
414 	int ret;
415 
416 	ret = gfs2_write_cache_jdata(mapping, wbc);
417 	if (ret == 0 && wbc->sync_mode == WB_SYNC_ALL) {
418 		gfs2_log_flush(sdp, ip->i_gl, GFS2_LOG_HEAD_FLUSH_NORMAL |
419 			       GFS2_LFC_JDATA_WPAGES);
420 		ret = gfs2_write_cache_jdata(mapping, wbc);
421 	}
422 	return ret;
423 }
424 
425 /**
426  * stuffed_readpage - Fill in a Linux page with stuffed file data
427  * @ip: the inode
428  * @page: the page
429  *
430  * Returns: errno
431  */
432 static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
433 {
434 	struct buffer_head *dibh;
435 	u64 dsize = i_size_read(&ip->i_inode);
436 	void *kaddr;
437 	int error;
438 
439 	/*
440 	 * Due to the order of unstuffing files and ->fault(), we can be
441 	 * asked for a zero page in the case of a stuffed file being extended,
442 	 * so we need to supply one here. It doesn't happen often.
443 	 */
444 	if (unlikely(page->index)) {
445 		zero_user(page, 0, PAGE_SIZE);
446 		SetPageUptodate(page);
447 		return 0;
448 	}
449 
450 	error = gfs2_meta_inode_buffer(ip, &dibh);
451 	if (error)
452 		return error;
453 
454 	kaddr = kmap_atomic(page);
455 	if (dsize > gfs2_max_stuffed_size(ip))
456 		dsize = gfs2_max_stuffed_size(ip);
457 	memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize);
458 	memset(kaddr + dsize, 0, PAGE_SIZE - dsize);
459 	kunmap_atomic(kaddr);
460 	flush_dcache_page(page);
461 	brelse(dibh);
462 	SetPageUptodate(page);
463 
464 	return 0;
465 }
466 
467 
468 static int __gfs2_readpage(void *file, struct page *page)
469 {
470 	struct inode *inode = page->mapping->host;
471 	struct gfs2_inode *ip = GFS2_I(inode);
472 	struct gfs2_sbd *sdp = GFS2_SB(inode);
473 	int error;
474 
475 	if (!gfs2_is_jdata(ip) ||
476 	    (i_blocksize(inode) == PAGE_SIZE && !page_has_buffers(page))) {
477 		error = iomap_readpage(page, &gfs2_iomap_ops);
478 	} else if (gfs2_is_stuffed(ip)) {
479 		error = stuffed_readpage(ip, page);
480 		unlock_page(page);
481 	} else {
482 		error = mpage_readpage(page, gfs2_block_map);
483 	}
484 
485 	if (unlikely(gfs2_withdrawn(sdp)))
486 		return -EIO;
487 
488 	return error;
489 }
490 
491 /**
492  * gfs2_readpage - read a page of a file
493  * @file: The file to read
494  * @page: The page of the file
495  */
496 
497 static int gfs2_readpage(struct file *file, struct page *page)
498 {
499 	return __gfs2_readpage(file, page);
500 }
501 
502 /**
503  * gfs2_internal_read - read an internal file
504  * @ip: The gfs2 inode
505  * @buf: The buffer to fill
506  * @pos: The file position
507  * @size: The amount to read
508  *
509  */
510 
511 int gfs2_internal_read(struct gfs2_inode *ip, char *buf, loff_t *pos,
512                        unsigned size)
513 {
514 	struct address_space *mapping = ip->i_inode.i_mapping;
515 	unsigned long index = *pos >> PAGE_SHIFT;
516 	unsigned offset = *pos & (PAGE_SIZE - 1);
517 	unsigned copied = 0;
518 	unsigned amt;
519 	struct page *page;
520 	void *p;
521 
522 	do {
523 		amt = size - copied;
524 		if (offset + size > PAGE_SIZE)
525 			amt = PAGE_SIZE - offset;
526 		page = read_cache_page(mapping, index, __gfs2_readpage, NULL);
527 		if (IS_ERR(page))
528 			return PTR_ERR(page);
529 		p = kmap_atomic(page);
530 		memcpy(buf + copied, p + offset, amt);
531 		kunmap_atomic(p);
532 		put_page(page);
533 		copied += amt;
534 		index++;
535 		offset = 0;
536 	} while(copied < size);
537 	(*pos) += size;
538 	return size;
539 }
540 
541 /**
542  * gfs2_readahead - Read a bunch of pages at once
543  * @rac: Read-ahead control structure
544  *
545  * Some notes:
546  * 1. This is only for readahead, so we can simply ignore any things
547  *    which are slightly inconvenient (such as locking conflicts between
548  *    the page lock and the glock) and return having done no I/O. Its
549  *    obviously not something we'd want to do on too regular a basis.
550  *    Any I/O we ignore at this time will be done via readpage later.
551  * 2. We don't handle stuffed files here we let readpage do the honours.
552  * 3. mpage_readahead() does most of the heavy lifting in the common case.
553  * 4. gfs2_block_map() is relied upon to set BH_Boundary in the right places.
554  */
555 
556 static void gfs2_readahead(struct readahead_control *rac)
557 {
558 	struct inode *inode = rac->mapping->host;
559 	struct gfs2_inode *ip = GFS2_I(inode);
560 
561 	if (gfs2_is_stuffed(ip))
562 		;
563 	else if (gfs2_is_jdata(ip))
564 		mpage_readahead(rac, gfs2_block_map);
565 	else
566 		iomap_readahead(rac, &gfs2_iomap_ops);
567 }
568 
569 /**
570  * adjust_fs_space - Adjusts the free space available due to gfs2_grow
571  * @inode: the rindex inode
572  */
573 void adjust_fs_space(struct inode *inode)
574 {
575 	struct gfs2_sbd *sdp = GFS2_SB(inode);
576 	struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
577 	struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
578 	struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
579 	struct buffer_head *m_bh;
580 	u64 fs_total, new_free;
581 
582 	if (gfs2_trans_begin(sdp, 2 * RES_STATFS, 0) != 0)
583 		return;
584 
585 	/* Total up the file system space, according to the latest rindex. */
586 	fs_total = gfs2_ri_total(sdp);
587 	if (gfs2_meta_inode_buffer(m_ip, &m_bh) != 0)
588 		goto out;
589 
590 	spin_lock(&sdp->sd_statfs_spin);
591 	gfs2_statfs_change_in(m_sc, m_bh->b_data +
592 			      sizeof(struct gfs2_dinode));
593 	if (fs_total > (m_sc->sc_total + l_sc->sc_total))
594 		new_free = fs_total - (m_sc->sc_total + l_sc->sc_total);
595 	else
596 		new_free = 0;
597 	spin_unlock(&sdp->sd_statfs_spin);
598 	fs_warn(sdp, "File system extended by %llu blocks.\n",
599 		(unsigned long long)new_free);
600 	gfs2_statfs_change(sdp, new_free, new_free, 0);
601 
602 	update_statfs(sdp, m_bh);
603 	brelse(m_bh);
604 out:
605 	sdp->sd_rindex_uptodate = 0;
606 	gfs2_trans_end(sdp);
607 }
608 
609 /**
610  * jdata_set_page_dirty - Page dirtying function
611  * @page: The page to dirty
612  *
613  * Returns: 1 if it dirtyed the page, or 0 otherwise
614  */
615 
616 static int jdata_set_page_dirty(struct page *page)
617 {
618 	if (current->journal_info)
619 		SetPageChecked(page);
620 	return __set_page_dirty_buffers(page);
621 }
622 
623 /**
624  * gfs2_bmap - Block map function
625  * @mapping: Address space info
626  * @lblock: The block to map
627  *
628  * Returns: The disk address for the block or 0 on hole or error
629  */
630 
631 static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
632 {
633 	struct gfs2_inode *ip = GFS2_I(mapping->host);
634 	struct gfs2_holder i_gh;
635 	sector_t dblock = 0;
636 	int error;
637 
638 	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
639 	if (error)
640 		return 0;
641 
642 	if (!gfs2_is_stuffed(ip))
643 		dblock = iomap_bmap(mapping, lblock, &gfs2_iomap_ops);
644 
645 	gfs2_glock_dq_uninit(&i_gh);
646 
647 	return dblock;
648 }
649 
650 static void gfs2_discard(struct gfs2_sbd *sdp, struct buffer_head *bh)
651 {
652 	struct gfs2_bufdata *bd;
653 
654 	lock_buffer(bh);
655 	gfs2_log_lock(sdp);
656 	clear_buffer_dirty(bh);
657 	bd = bh->b_private;
658 	if (bd) {
659 		if (!list_empty(&bd->bd_list) && !buffer_pinned(bh))
660 			list_del_init(&bd->bd_list);
661 		else {
662 			spin_lock(&sdp->sd_ail_lock);
663 			gfs2_remove_from_journal(bh, REMOVE_JDATA);
664 			spin_unlock(&sdp->sd_ail_lock);
665 		}
666 	}
667 	bh->b_bdev = NULL;
668 	clear_buffer_mapped(bh);
669 	clear_buffer_req(bh);
670 	clear_buffer_new(bh);
671 	gfs2_log_unlock(sdp);
672 	unlock_buffer(bh);
673 }
674 
675 static void gfs2_invalidatepage(struct page *page, unsigned int offset,
676 				unsigned int length)
677 {
678 	struct gfs2_sbd *sdp = GFS2_SB(page->mapping->host);
679 	unsigned int stop = offset + length;
680 	int partial_page = (offset || length < PAGE_SIZE);
681 	struct buffer_head *bh, *head;
682 	unsigned long pos = 0;
683 
684 	BUG_ON(!PageLocked(page));
685 	if (!partial_page)
686 		ClearPageChecked(page);
687 	if (!page_has_buffers(page))
688 		goto out;
689 
690 	bh = head = page_buffers(page);
691 	do {
692 		if (pos + bh->b_size > stop)
693 			return;
694 
695 		if (offset <= pos)
696 			gfs2_discard(sdp, bh);
697 		pos += bh->b_size;
698 		bh = bh->b_this_page;
699 	} while (bh != head);
700 out:
701 	if (!partial_page)
702 		try_to_release_page(page, 0);
703 }
704 
705 /**
706  * gfs2_releasepage - free the metadata associated with a page
707  * @page: the page that's being released
708  * @gfp_mask: passed from Linux VFS, ignored by us
709  *
710  * Calls try_to_free_buffers() to free the buffers and put the page if the
711  * buffers can be released.
712  *
713  * Returns: 1 if the page was put or else 0
714  */
715 
716 int gfs2_releasepage(struct page *page, gfp_t gfp_mask)
717 {
718 	struct address_space *mapping = page->mapping;
719 	struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
720 	struct buffer_head *bh, *head;
721 	struct gfs2_bufdata *bd;
722 
723 	if (!page_has_buffers(page))
724 		return 0;
725 
726 	/*
727 	 * From xfs_vm_releasepage: mm accommodates an old ext3 case where
728 	 * clean pages might not have had the dirty bit cleared.  Thus, it can
729 	 * send actual dirty pages to ->releasepage() via shrink_active_list().
730 	 *
731 	 * As a workaround, we skip pages that contain dirty buffers below.
732 	 * Once ->releasepage isn't called on dirty pages anymore, we can warn
733 	 * on dirty buffers like we used to here again.
734 	 */
735 
736 	gfs2_log_lock(sdp);
737 	head = bh = page_buffers(page);
738 	do {
739 		if (atomic_read(&bh->b_count))
740 			goto cannot_release;
741 		bd = bh->b_private;
742 		if (bd && bd->bd_tr)
743 			goto cannot_release;
744 		if (buffer_dirty(bh) || WARN_ON(buffer_pinned(bh)))
745 			goto cannot_release;
746 		bh = bh->b_this_page;
747 	} while(bh != head);
748 
749 	head = bh = page_buffers(page);
750 	do {
751 		bd = bh->b_private;
752 		if (bd) {
753 			gfs2_assert_warn(sdp, bd->bd_bh == bh);
754 			bd->bd_bh = NULL;
755 			bh->b_private = NULL;
756 			/*
757 			 * The bd may still be queued as a revoke, in which
758 			 * case we must not dequeue nor free it.
759 			 */
760 			if (!bd->bd_blkno && !list_empty(&bd->bd_list))
761 				list_del_init(&bd->bd_list);
762 			if (list_empty(&bd->bd_list))
763 				kmem_cache_free(gfs2_bufdata_cachep, bd);
764 		}
765 
766 		bh = bh->b_this_page;
767 	} while (bh != head);
768 	gfs2_log_unlock(sdp);
769 
770 	return try_to_free_buffers(page);
771 
772 cannot_release:
773 	gfs2_log_unlock(sdp);
774 	return 0;
775 }
776 
777 static const struct address_space_operations gfs2_aops = {
778 	.writepage = gfs2_writepage,
779 	.writepages = gfs2_writepages,
780 	.readpage = gfs2_readpage,
781 	.readahead = gfs2_readahead,
782 	.set_page_dirty = __set_page_dirty_nobuffers,
783 	.releasepage = iomap_releasepage,
784 	.invalidatepage = iomap_invalidatepage,
785 	.bmap = gfs2_bmap,
786 	.direct_IO = noop_direct_IO,
787 	.migratepage = iomap_migrate_page,
788 	.is_partially_uptodate = iomap_is_partially_uptodate,
789 	.error_remove_page = generic_error_remove_page,
790 };
791 
792 static const struct address_space_operations gfs2_jdata_aops = {
793 	.writepage = gfs2_jdata_writepage,
794 	.writepages = gfs2_jdata_writepages,
795 	.readpage = gfs2_readpage,
796 	.readahead = gfs2_readahead,
797 	.set_page_dirty = jdata_set_page_dirty,
798 	.bmap = gfs2_bmap,
799 	.invalidatepage = gfs2_invalidatepage,
800 	.releasepage = gfs2_releasepage,
801 	.is_partially_uptodate = block_is_partially_uptodate,
802 	.error_remove_page = generic_error_remove_page,
803 };
804 
805 void gfs2_set_aops(struct inode *inode)
806 {
807 	if (gfs2_is_jdata(GFS2_I(inode)))
808 		inode->i_mapping->a_ops = &gfs2_jdata_aops;
809 	else
810 		inode->i_mapping->a_ops = &gfs2_aops;
811 }
812