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 
gfs2_page_add_databufs(struct gfs2_inode * ip,struct page * page,unsigned int from,unsigned int len)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 
gfs2_get_block_noalloc(struct inode * inode,sector_t lblock,struct buffer_head * bh_result,int create)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_write_jdata_page - gfs2 jdata-specific version of block_write_full_page
86  * @page: The page to write
87  * @wbc: The writeback control
88  *
89  * This is the same as calling block_write_full_page, but it also
90  * writes pages outside of i_size
91  */
gfs2_write_jdata_page(struct page * page,struct writeback_control * wbc)92 static int gfs2_write_jdata_page(struct page *page,
93 				 struct writeback_control *wbc)
94 {
95 	struct inode * const inode = page->mapping->host;
96 	loff_t i_size = i_size_read(inode);
97 	const pgoff_t end_index = i_size >> PAGE_SHIFT;
98 	unsigned offset;
99 
100 	/*
101 	 * The page straddles i_size.  It must be zeroed out on each and every
102 	 * writepage invocation because it may be mmapped.  "A file is mapped
103 	 * in multiples of the page size.  For a file that is not a multiple of
104 	 * the  page size, the remaining memory is zeroed when mapped, and
105 	 * writes to that region are not written out to the file."
106 	 */
107 	offset = i_size & (PAGE_SIZE - 1);
108 	if (page->index == end_index && offset)
109 		zero_user_segment(page, offset, PAGE_SIZE);
110 
111 	return __block_write_full_page(inode, page, gfs2_get_block_noalloc, wbc,
112 				       end_buffer_async_write);
113 }
114 
115 /**
116  * __gfs2_jdata_writepage - The core of jdata writepage
117  * @page: The page to write
118  * @wbc: The writeback control
119  *
120  * This is shared between writepage and writepages and implements the
121  * core of the writepage operation. If a transaction is required then
122  * PageChecked will have been set and the transaction will have
123  * already been started before this is called.
124  */
125 
__gfs2_jdata_writepage(struct page * page,struct writeback_control * wbc)126 static int __gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
127 {
128 	struct inode *inode = page->mapping->host;
129 	struct gfs2_inode *ip = GFS2_I(inode);
130 	struct gfs2_sbd *sdp = GFS2_SB(inode);
131 
132 	if (PageChecked(page)) {
133 		ClearPageChecked(page);
134 		if (!page_has_buffers(page)) {
135 			create_empty_buffers(page, inode->i_sb->s_blocksize,
136 					     BIT(BH_Dirty)|BIT(BH_Uptodate));
137 		}
138 		gfs2_page_add_databufs(ip, page, 0, sdp->sd_vfs->s_blocksize);
139 	}
140 	return gfs2_write_jdata_page(page, wbc);
141 }
142 
143 /**
144  * gfs2_jdata_writepage - Write complete page
145  * @page: Page to write
146  * @wbc: The writeback control
147  *
148  * Returns: errno
149  *
150  */
151 
gfs2_jdata_writepage(struct page * page,struct writeback_control * wbc)152 static int gfs2_jdata_writepage(struct page *page, struct writeback_control *wbc)
153 {
154 	struct inode *inode = page->mapping->host;
155 	struct gfs2_inode *ip = GFS2_I(inode);
156 	struct gfs2_sbd *sdp = GFS2_SB(inode);
157 
158 	if (gfs2_assert_withdraw(sdp, gfs2_glock_is_held_excl(ip->i_gl)))
159 		goto out;
160 	if (PageChecked(page) || current->journal_info)
161 		goto out_ignore;
162 	return __gfs2_jdata_writepage(page, wbc);
163 
164 out_ignore:
165 	redirty_page_for_writepage(wbc, page);
166 out:
167 	unlock_page(page);
168 	return 0;
169 }
170 
171 /**
172  * gfs2_writepages - Write a bunch of dirty pages back to disk
173  * @mapping: The mapping to write
174  * @wbc: Write-back control
175  *
176  * Used for both ordered and writeback modes.
177  */
gfs2_writepages(struct address_space * mapping,struct writeback_control * wbc)178 static int gfs2_writepages(struct address_space *mapping,
179 			   struct writeback_control *wbc)
180 {
181 	struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
182 	struct iomap_writepage_ctx wpc = { };
183 	int ret;
184 
185 	/*
186 	 * Even if we didn't write any pages here, we might still be holding
187 	 * dirty pages in the ail. We forcibly flush the ail because we don't
188 	 * want balance_dirty_pages() to loop indefinitely trying to write out
189 	 * pages held in the ail that it can't find.
190 	 */
191 	ret = iomap_writepages(mapping, wbc, &wpc, &gfs2_writeback_ops);
192 	if (ret == 0)
193 		set_bit(SDF_FORCE_AIL_FLUSH, &sdp->sd_flags);
194 	return ret;
195 }
196 
197 /**
198  * gfs2_write_jdata_pagevec - Write back a pagevec's worth of pages
199  * @mapping: The mapping
200  * @wbc: The writeback control
201  * @pvec: The vector of pages
202  * @nr_pages: The number of pages to write
203  * @done_index: Page index
204  *
205  * Returns: non-zero if loop should terminate, zero otherwise
206  */
207 
gfs2_write_jdata_pagevec(struct address_space * mapping,struct writeback_control * wbc,struct pagevec * pvec,int nr_pages,pgoff_t * done_index)208 static int gfs2_write_jdata_pagevec(struct address_space *mapping,
209 				    struct writeback_control *wbc,
210 				    struct pagevec *pvec,
211 				    int nr_pages,
212 				    pgoff_t *done_index)
213 {
214 	struct inode *inode = mapping->host;
215 	struct gfs2_sbd *sdp = GFS2_SB(inode);
216 	unsigned nrblocks = nr_pages * (PAGE_SIZE >> inode->i_blkbits);
217 	int i;
218 	int ret;
219 
220 	ret = gfs2_trans_begin(sdp, nrblocks, nrblocks);
221 	if (ret < 0)
222 		return ret;
223 
224 	for(i = 0; i < nr_pages; i++) {
225 		struct page *page = pvec->pages[i];
226 
227 		*done_index = page->index;
228 
229 		lock_page(page);
230 
231 		if (unlikely(page->mapping != mapping)) {
232 continue_unlock:
233 			unlock_page(page);
234 			continue;
235 		}
236 
237 		if (!PageDirty(page)) {
238 			/* someone wrote it for us */
239 			goto continue_unlock;
240 		}
241 
242 		if (PageWriteback(page)) {
243 			if (wbc->sync_mode != WB_SYNC_NONE)
244 				wait_on_page_writeback(page);
245 			else
246 				goto continue_unlock;
247 		}
248 
249 		BUG_ON(PageWriteback(page));
250 		if (!clear_page_dirty_for_io(page))
251 			goto continue_unlock;
252 
253 		trace_wbc_writepage(wbc, inode_to_bdi(inode));
254 
255 		ret = __gfs2_jdata_writepage(page, wbc);
256 		if (unlikely(ret)) {
257 			if (ret == AOP_WRITEPAGE_ACTIVATE) {
258 				unlock_page(page);
259 				ret = 0;
260 			} else {
261 
262 				/*
263 				 * done_index is set past this page,
264 				 * so media errors will not choke
265 				 * background writeout for the entire
266 				 * file. This has consequences for
267 				 * range_cyclic semantics (ie. it may
268 				 * not be suitable for data integrity
269 				 * writeout).
270 				 */
271 				*done_index = page->index + 1;
272 				ret = 1;
273 				break;
274 			}
275 		}
276 
277 		/*
278 		 * We stop writing back only if we are not doing
279 		 * integrity sync. In case of integrity sync we have to
280 		 * keep going until we have written all the pages
281 		 * we tagged for writeback prior to entering this loop.
282 		 */
283 		if (--wbc->nr_to_write <= 0 && wbc->sync_mode == WB_SYNC_NONE) {
284 			ret = 1;
285 			break;
286 		}
287 
288 	}
289 	gfs2_trans_end(sdp);
290 	return ret;
291 }
292 
293 /**
294  * gfs2_write_cache_jdata - Like write_cache_pages but different
295  * @mapping: The mapping to write
296  * @wbc: The writeback control
297  *
298  * The reason that we use our own function here is that we need to
299  * start transactions before we grab page locks. This allows us
300  * to get the ordering right.
301  */
302 
gfs2_write_cache_jdata(struct address_space * mapping,struct writeback_control * wbc)303 static int gfs2_write_cache_jdata(struct address_space *mapping,
304 				  struct writeback_control *wbc)
305 {
306 	int ret = 0;
307 	int done = 0;
308 	struct pagevec pvec;
309 	int nr_pages;
310 	pgoff_t writeback_index;
311 	pgoff_t index;
312 	pgoff_t end;
313 	pgoff_t done_index;
314 	int cycled;
315 	int range_whole = 0;
316 	xa_mark_t tag;
317 
318 	pagevec_init(&pvec);
319 	if (wbc->range_cyclic) {
320 		writeback_index = mapping->writeback_index; /* prev offset */
321 		index = writeback_index;
322 		if (index == 0)
323 			cycled = 1;
324 		else
325 			cycled = 0;
326 		end = -1;
327 	} else {
328 		index = wbc->range_start >> PAGE_SHIFT;
329 		end = wbc->range_end >> PAGE_SHIFT;
330 		if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
331 			range_whole = 1;
332 		cycled = 1; /* ignore range_cyclic tests */
333 	}
334 	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
335 		tag = PAGECACHE_TAG_TOWRITE;
336 	else
337 		tag = PAGECACHE_TAG_DIRTY;
338 
339 retry:
340 	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
341 		tag_pages_for_writeback(mapping, index, end);
342 	done_index = index;
343 	while (!done && (index <= end)) {
344 		nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index, end,
345 				tag);
346 		if (nr_pages == 0)
347 			break;
348 
349 		ret = gfs2_write_jdata_pagevec(mapping, wbc, &pvec, nr_pages, &done_index);
350 		if (ret)
351 			done = 1;
352 		if (ret > 0)
353 			ret = 0;
354 		pagevec_release(&pvec);
355 		cond_resched();
356 	}
357 
358 	if (!cycled && !done) {
359 		/*
360 		 * range_cyclic:
361 		 * We hit the last page and there is more work to be done: wrap
362 		 * back to the start of the file
363 		 */
364 		cycled = 1;
365 		index = 0;
366 		end = writeback_index - 1;
367 		goto retry;
368 	}
369 
370 	if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
371 		mapping->writeback_index = done_index;
372 
373 	return ret;
374 }
375 
376 
377 /**
378  * gfs2_jdata_writepages - Write a bunch of dirty pages back to disk
379  * @mapping: The mapping to write
380  * @wbc: The writeback control
381  *
382  */
383 
gfs2_jdata_writepages(struct address_space * mapping,struct writeback_control * wbc)384 static int gfs2_jdata_writepages(struct address_space *mapping,
385 				 struct writeback_control *wbc)
386 {
387 	struct gfs2_inode *ip = GFS2_I(mapping->host);
388 	struct gfs2_sbd *sdp = GFS2_SB(mapping->host);
389 	int ret;
390 
391 	ret = gfs2_write_cache_jdata(mapping, wbc);
392 	if (ret == 0 && wbc->sync_mode == WB_SYNC_ALL) {
393 		gfs2_log_flush(sdp, ip->i_gl, GFS2_LOG_HEAD_FLUSH_NORMAL |
394 			       GFS2_LFC_JDATA_WPAGES);
395 		ret = gfs2_write_cache_jdata(mapping, wbc);
396 	}
397 	return ret;
398 }
399 
400 /**
401  * stuffed_readpage - Fill in a Linux page with stuffed file data
402  * @ip: the inode
403  * @page: the page
404  *
405  * Returns: errno
406  */
stuffed_readpage(struct gfs2_inode * ip,struct page * page)407 static int stuffed_readpage(struct gfs2_inode *ip, struct page *page)
408 {
409 	struct buffer_head *dibh;
410 	u64 dsize = i_size_read(&ip->i_inode);
411 	void *kaddr;
412 	int error;
413 
414 	/*
415 	 * Due to the order of unstuffing files and ->fault(), we can be
416 	 * asked for a zero page in the case of a stuffed file being extended,
417 	 * so we need to supply one here. It doesn't happen often.
418 	 */
419 	if (unlikely(page->index)) {
420 		zero_user(page, 0, PAGE_SIZE);
421 		SetPageUptodate(page);
422 		return 0;
423 	}
424 
425 	error = gfs2_meta_inode_buffer(ip, &dibh);
426 	if (error)
427 		return error;
428 
429 	kaddr = kmap_atomic(page);
430 	if (dsize > gfs2_max_stuffed_size(ip))
431 		dsize = gfs2_max_stuffed_size(ip);
432 	memcpy(kaddr, dibh->b_data + sizeof(struct gfs2_dinode), dsize);
433 	memset(kaddr + dsize, 0, PAGE_SIZE - dsize);
434 	kunmap_atomic(kaddr);
435 	flush_dcache_page(page);
436 	brelse(dibh);
437 	SetPageUptodate(page);
438 
439 	return 0;
440 }
441 
442 /**
443  * gfs2_read_folio - read a folio from a file
444  * @file: The file to read
445  * @folio: The folio in the file
446  */
gfs2_read_folio(struct file * file,struct folio * folio)447 static int gfs2_read_folio(struct file *file, struct folio *folio)
448 {
449 	struct inode *inode = folio->mapping->host;
450 	struct gfs2_inode *ip = GFS2_I(inode);
451 	struct gfs2_sbd *sdp = GFS2_SB(inode);
452 	int error;
453 
454 	if (!gfs2_is_jdata(ip) ||
455 	    (i_blocksize(inode) == PAGE_SIZE && !folio_buffers(folio))) {
456 		error = iomap_read_folio(folio, &gfs2_iomap_ops);
457 	} else if (gfs2_is_stuffed(ip)) {
458 		error = stuffed_readpage(ip, &folio->page);
459 		folio_unlock(folio);
460 	} else {
461 		error = mpage_read_folio(folio, gfs2_block_map);
462 	}
463 
464 	if (unlikely(gfs2_withdrawn(sdp)))
465 		return -EIO;
466 
467 	return error;
468 }
469 
470 /**
471  * gfs2_internal_read - read an internal file
472  * @ip: The gfs2 inode
473  * @buf: The buffer to fill
474  * @pos: The file position
475  * @size: The amount to read
476  *
477  */
478 
gfs2_internal_read(struct gfs2_inode * ip,char * buf,loff_t * pos,unsigned size)479 int gfs2_internal_read(struct gfs2_inode *ip, char *buf, loff_t *pos,
480                        unsigned size)
481 {
482 	struct address_space *mapping = ip->i_inode.i_mapping;
483 	unsigned long index = *pos >> PAGE_SHIFT;
484 	unsigned offset = *pos & (PAGE_SIZE - 1);
485 	unsigned copied = 0;
486 	unsigned amt;
487 	struct page *page;
488 	void *p;
489 
490 	do {
491 		amt = size - copied;
492 		if (offset + size > PAGE_SIZE)
493 			amt = PAGE_SIZE - offset;
494 		page = read_cache_page(mapping, index, gfs2_read_folio, NULL);
495 		if (IS_ERR(page))
496 			return PTR_ERR(page);
497 		p = kmap_atomic(page);
498 		memcpy(buf + copied, p + offset, amt);
499 		kunmap_atomic(p);
500 		put_page(page);
501 		copied += amt;
502 		index++;
503 		offset = 0;
504 	} while(copied < size);
505 	(*pos) += size;
506 	return size;
507 }
508 
509 /**
510  * gfs2_readahead - Read a bunch of pages at once
511  * @rac: Read-ahead control structure
512  *
513  * Some notes:
514  * 1. This is only for readahead, so we can simply ignore any things
515  *    which are slightly inconvenient (such as locking conflicts between
516  *    the page lock and the glock) and return having done no I/O. Its
517  *    obviously not something we'd want to do on too regular a basis.
518  *    Any I/O we ignore at this time will be done via readpage later.
519  * 2. We don't handle stuffed files here we let readpage do the honours.
520  * 3. mpage_readahead() does most of the heavy lifting in the common case.
521  * 4. gfs2_block_map() is relied upon to set BH_Boundary in the right places.
522  */
523 
gfs2_readahead(struct readahead_control * rac)524 static void gfs2_readahead(struct readahead_control *rac)
525 {
526 	struct inode *inode = rac->mapping->host;
527 	struct gfs2_inode *ip = GFS2_I(inode);
528 
529 	if (gfs2_is_stuffed(ip))
530 		;
531 	else if (gfs2_is_jdata(ip))
532 		mpage_readahead(rac, gfs2_block_map);
533 	else
534 		iomap_readahead(rac, &gfs2_iomap_ops);
535 }
536 
537 /**
538  * adjust_fs_space - Adjusts the free space available due to gfs2_grow
539  * @inode: the rindex inode
540  */
adjust_fs_space(struct inode * inode)541 void adjust_fs_space(struct inode *inode)
542 {
543 	struct gfs2_sbd *sdp = GFS2_SB(inode);
544 	struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
545 	struct gfs2_statfs_change_host *m_sc = &sdp->sd_statfs_master;
546 	struct gfs2_statfs_change_host *l_sc = &sdp->sd_statfs_local;
547 	struct buffer_head *m_bh;
548 	u64 fs_total, new_free;
549 
550 	if (gfs2_trans_begin(sdp, 2 * RES_STATFS, 0) != 0)
551 		return;
552 
553 	/* Total up the file system space, according to the latest rindex. */
554 	fs_total = gfs2_ri_total(sdp);
555 	if (gfs2_meta_inode_buffer(m_ip, &m_bh) != 0)
556 		goto out;
557 
558 	spin_lock(&sdp->sd_statfs_spin);
559 	gfs2_statfs_change_in(m_sc, m_bh->b_data +
560 			      sizeof(struct gfs2_dinode));
561 	if (fs_total > (m_sc->sc_total + l_sc->sc_total))
562 		new_free = fs_total - (m_sc->sc_total + l_sc->sc_total);
563 	else
564 		new_free = 0;
565 	spin_unlock(&sdp->sd_statfs_spin);
566 	fs_warn(sdp, "File system extended by %llu blocks.\n",
567 		(unsigned long long)new_free);
568 	gfs2_statfs_change(sdp, new_free, new_free, 0);
569 
570 	update_statfs(sdp, m_bh);
571 	brelse(m_bh);
572 out:
573 	sdp->sd_rindex_uptodate = 0;
574 	gfs2_trans_end(sdp);
575 }
576 
jdata_dirty_folio(struct address_space * mapping,struct folio * folio)577 static bool jdata_dirty_folio(struct address_space *mapping,
578 		struct folio *folio)
579 {
580 	if (current->journal_info)
581 		folio_set_checked(folio);
582 	return block_dirty_folio(mapping, folio);
583 }
584 
585 /**
586  * gfs2_bmap - Block map function
587  * @mapping: Address space info
588  * @lblock: The block to map
589  *
590  * Returns: The disk address for the block or 0 on hole or error
591  */
592 
gfs2_bmap(struct address_space * mapping,sector_t lblock)593 static sector_t gfs2_bmap(struct address_space *mapping, sector_t lblock)
594 {
595 	struct gfs2_inode *ip = GFS2_I(mapping->host);
596 	struct gfs2_holder i_gh;
597 	sector_t dblock = 0;
598 	int error;
599 
600 	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
601 	if (error)
602 		return 0;
603 
604 	if (!gfs2_is_stuffed(ip))
605 		dblock = iomap_bmap(mapping, lblock, &gfs2_iomap_ops);
606 
607 	gfs2_glock_dq_uninit(&i_gh);
608 
609 	return dblock;
610 }
611 
gfs2_discard(struct gfs2_sbd * sdp,struct buffer_head * bh)612 static void gfs2_discard(struct gfs2_sbd *sdp, struct buffer_head *bh)
613 {
614 	struct gfs2_bufdata *bd;
615 
616 	lock_buffer(bh);
617 	gfs2_log_lock(sdp);
618 	clear_buffer_dirty(bh);
619 	bd = bh->b_private;
620 	if (bd) {
621 		if (!list_empty(&bd->bd_list) && !buffer_pinned(bh))
622 			list_del_init(&bd->bd_list);
623 		else {
624 			spin_lock(&sdp->sd_ail_lock);
625 			gfs2_remove_from_journal(bh, REMOVE_JDATA);
626 			spin_unlock(&sdp->sd_ail_lock);
627 		}
628 	}
629 	bh->b_bdev = NULL;
630 	clear_buffer_mapped(bh);
631 	clear_buffer_req(bh);
632 	clear_buffer_new(bh);
633 	gfs2_log_unlock(sdp);
634 	unlock_buffer(bh);
635 }
636 
gfs2_invalidate_folio(struct folio * folio,size_t offset,size_t length)637 static void gfs2_invalidate_folio(struct folio *folio, size_t offset,
638 				size_t length)
639 {
640 	struct gfs2_sbd *sdp = GFS2_SB(folio->mapping->host);
641 	size_t stop = offset + length;
642 	int partial_page = (offset || length < folio_size(folio));
643 	struct buffer_head *bh, *head;
644 	unsigned long pos = 0;
645 
646 	BUG_ON(!folio_test_locked(folio));
647 	if (!partial_page)
648 		folio_clear_checked(folio);
649 	head = folio_buffers(folio);
650 	if (!head)
651 		goto out;
652 
653 	bh = head;
654 	do {
655 		if (pos + bh->b_size > stop)
656 			return;
657 
658 		if (offset <= pos)
659 			gfs2_discard(sdp, bh);
660 		pos += bh->b_size;
661 		bh = bh->b_this_page;
662 	} while (bh != head);
663 out:
664 	if (!partial_page)
665 		filemap_release_folio(folio, 0);
666 }
667 
668 /**
669  * gfs2_release_folio - free the metadata associated with a folio
670  * @folio: the folio that's being released
671  * @gfp_mask: passed from Linux VFS, ignored by us
672  *
673  * Calls try_to_free_buffers() to free the buffers and put the folio if the
674  * buffers can be released.
675  *
676  * Returns: true if the folio was put or else false
677  */
678 
gfs2_release_folio(struct folio * folio,gfp_t gfp_mask)679 bool gfs2_release_folio(struct folio *folio, gfp_t gfp_mask)
680 {
681 	struct address_space *mapping = folio->mapping;
682 	struct gfs2_sbd *sdp = gfs2_mapping2sbd(mapping);
683 	struct buffer_head *bh, *head;
684 	struct gfs2_bufdata *bd;
685 
686 	head = folio_buffers(folio);
687 	if (!head)
688 		return false;
689 
690 	/*
691 	 * mm accommodates an old ext3 case where clean folios might
692 	 * not have had the dirty bit cleared.	Thus, it can send actual
693 	 * dirty folios to ->release_folio() via shrink_active_list().
694 	 *
695 	 * As a workaround, we skip folios that contain dirty buffers
696 	 * below.  Once ->release_folio isn't called on dirty folios
697 	 * anymore, we can warn on dirty buffers like we used to here
698 	 * again.
699 	 */
700 
701 	gfs2_log_lock(sdp);
702 	bh = head;
703 	do {
704 		if (atomic_read(&bh->b_count))
705 			goto cannot_release;
706 		bd = bh->b_private;
707 		if (bd && bd->bd_tr)
708 			goto cannot_release;
709 		if (buffer_dirty(bh) || WARN_ON(buffer_pinned(bh)))
710 			goto cannot_release;
711 		bh = bh->b_this_page;
712 	} while (bh != head);
713 
714 	bh = head;
715 	do {
716 		bd = bh->b_private;
717 		if (bd) {
718 			gfs2_assert_warn(sdp, bd->bd_bh == bh);
719 			bd->bd_bh = NULL;
720 			bh->b_private = NULL;
721 			/*
722 			 * The bd may still be queued as a revoke, in which
723 			 * case we must not dequeue nor free it.
724 			 */
725 			if (!bd->bd_blkno && !list_empty(&bd->bd_list))
726 				list_del_init(&bd->bd_list);
727 			if (list_empty(&bd->bd_list))
728 				kmem_cache_free(gfs2_bufdata_cachep, bd);
729 		}
730 
731 		bh = bh->b_this_page;
732 	} while (bh != head);
733 	gfs2_log_unlock(sdp);
734 
735 	return try_to_free_buffers(folio);
736 
737 cannot_release:
738 	gfs2_log_unlock(sdp);
739 	return false;
740 }
741 
742 static const struct address_space_operations gfs2_aops = {
743 	.writepages = gfs2_writepages,
744 	.read_folio = gfs2_read_folio,
745 	.readahead = gfs2_readahead,
746 	.dirty_folio = filemap_dirty_folio,
747 	.release_folio = iomap_release_folio,
748 	.invalidate_folio = iomap_invalidate_folio,
749 	.bmap = gfs2_bmap,
750 	.direct_IO = noop_direct_IO,
751 	.migrate_folio = filemap_migrate_folio,
752 	.is_partially_uptodate = iomap_is_partially_uptodate,
753 	.error_remove_page = generic_error_remove_page,
754 };
755 
756 static const struct address_space_operations gfs2_jdata_aops = {
757 	.writepage = gfs2_jdata_writepage,
758 	.writepages = gfs2_jdata_writepages,
759 	.read_folio = gfs2_read_folio,
760 	.readahead = gfs2_readahead,
761 	.dirty_folio = jdata_dirty_folio,
762 	.bmap = gfs2_bmap,
763 	.invalidate_folio = gfs2_invalidate_folio,
764 	.release_folio = gfs2_release_folio,
765 	.is_partially_uptodate = block_is_partially_uptodate,
766 	.error_remove_page = generic_error_remove_page,
767 };
768 
gfs2_set_aops(struct inode * inode)769 void gfs2_set_aops(struct inode *inode)
770 {
771 	if (gfs2_is_jdata(GFS2_I(inode)))
772 		inode->i_mapping->a_ops = &gfs2_jdata_aops;
773 	else
774 		inode->i_mapping->a_ops = &gfs2_aops;
775 }
776