[linux-2.6-block.git] / fs / nilfs2 / page.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Buffer/page management specific to NILFS
 *
 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
 *
 * Written by Ryusuke Konishi and Seiji Kihara.
 */

#include <linux/pagemap.h>
#include <linux/writeback.h>
#include <linux/swap.h>
#include <linux/bitops.h>
#include <linux/page-flags.h>
#include <linux/list.h>
#include <linux/highmem.h>
#include <linux/pagevec.h>
#include <linux/gfp.h>
#include "nilfs.h"
#include "page.h"
#include "mdt.h"


#define NILFS_BUFFER_INHERENT_BITS					\
	(BIT(BH_Uptodate) | BIT(BH_Mapped) | BIT(BH_NILFS_Node) |	\
	 BIT(BH_NILFS_Volatile) | BIT(BH_NILFS_Checked))

static struct buffer_head *__nilfs_get_folio_block(struct folio *folio,
		unsigned long block, pgoff_t index, int blkbits,
		unsigned long b_state)

{
	unsigned long first_block;
	struct buffer_head *bh = folio_buffers(folio);

	if (!bh)
		bh = create_empty_buffers(folio, 1 << blkbits, b_state);

	first_block = (unsigned long)index << (PAGE_SHIFT - blkbits);
	bh = get_nth_bh(bh, block - first_block);

	touch_buffer(bh);
	wait_on_buffer(bh);
	return bh;
}

struct buffer_head *nilfs_grab_buffer(struct inode *inode,
				      struct address_space *mapping,
				      unsigned long blkoff,
				      unsigned long b_state)
{
	int blkbits = inode->i_blkbits;
	pgoff_t index = blkoff >> (PAGE_SHIFT - blkbits);
	struct folio *folio;
	struct buffer_head *bh;

	folio = filemap_grab_folio(mapping, index);
	if (IS_ERR(folio))
		return NULL;

	bh = __nilfs_get_folio_block(folio, blkoff, index, blkbits, b_state);
	if (unlikely(!bh)) {
		folio_unlock(folio);
		folio_put(folio);
		return NULL;
	}
	return bh;
}

/**
 * nilfs_forget_buffer - discard dirty state
 * @bh: buffer head of the buffer to be discarded
 */
void nilfs_forget_buffer(struct buffer_head *bh)
{
	struct folio *folio = bh->b_folio;
	const unsigned long clear_bits =
		(BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
		 BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
		 BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));

	lock_buffer(bh);
	set_mask_bits(&bh->b_state, clear_bits, 0);
	if (nilfs_folio_buffers_clean(folio))
		__nilfs_clear_folio_dirty(folio);

	bh->b_blocknr = -1;
	folio_clear_uptodate(folio);
	folio_clear_mappedtodisk(folio);
	unlock_buffer(bh);
	brelse(bh);
}

/**
 * nilfs_copy_buffer -- copy buffer data and flags
 * @dbh: destination buffer
 * @sbh: source buffer
 */
void nilfs_copy_buffer(struct buffer_head *dbh, struct buffer_head *sbh)
{
	void *kaddr0, *kaddr1;
	unsigned long bits;
	struct page *spage = sbh->b_page, *dpage = dbh->b_page;
	struct buffer_head *bh;

	kaddr0 = kmap_local_page(spage);
	kaddr1 = kmap_local_page(dpage);
	memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
	kunmap_local(kaddr1);
	kunmap_local(kaddr0);

	dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
	dbh->b_blocknr = sbh->b_blocknr;
	dbh->b_bdev = sbh->b_bdev;

	bh = dbh;
	bits = sbh->b_state & (BIT(BH_Uptodate) | BIT(BH_Mapped));
	while ((bh = bh->b_this_page) != dbh) {
		lock_buffer(bh);
		bits &= bh->b_state;
		unlock_buffer(bh);
	}
	if (bits & BIT(BH_Uptodate))
		SetPageUptodate(dpage);
	else
		ClearPageUptodate(dpage);
	if (bits & BIT(BH_Mapped))
		SetPageMappedToDisk(dpage);
	else
		ClearPageMappedToDisk(dpage);
}

/**
 * nilfs_folio_buffers_clean - Check if a folio has dirty buffers or not.
 * @folio: Folio to be checked.
 *
 * nilfs_folio_buffers_clean() returns false if the folio has dirty buffers.
 * Otherwise, it returns true.
 */
bool nilfs_folio_buffers_clean(struct folio *folio)
{
	struct buffer_head *bh, *head;

	bh = head = folio_buffers(folio);
	do {
		if (buffer_dirty(bh))
			return false;
		bh = bh->b_this_page;
	} while (bh != head);
	return true;
}

void nilfs_folio_bug(struct folio *folio)
{
	struct buffer_head *bh, *head;
	struct address_space *m;
	unsigned long ino;

	if (unlikely(!folio)) {
		printk(KERN_CRIT "NILFS_FOLIO_BUG(NULL)\n");
		return;
	}

	m = folio->mapping;
	ino = m ? m->host->i_ino : 0;

	printk(KERN_CRIT "NILFS_FOLIO_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
	       "mapping=%p ino=%lu\n",
	       folio, folio_ref_count(folio),
	       (unsigned long long)folio->index, folio->flags, m, ino);

	head = folio_buffers(folio);
	if (head) {
		int i = 0;

		bh = head;
		do {
			printk(KERN_CRIT
			       " BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
			       i++, bh, atomic_read(&bh->b_count),
			       (unsigned long long)bh->b_blocknr, bh->b_state);
			bh = bh->b_this_page;
		} while (bh != head);
	}
}

/**
 * nilfs_copy_folio -- copy the folio with buffers
 * @dst: destination folio
 * @src: source folio
 * @copy_dirty: flag whether to copy dirty states on the folio's buffer heads.
 *
 * This function is for both data folios and btnode folios.  The dirty flag
 * should be treated by caller.  The folio must not be under i/o.
 * Both src and dst folio must be locked
 */
static void nilfs_copy_folio(struct folio *dst, struct folio *src,
		bool copy_dirty)
{
	struct buffer_head *dbh, *dbufs, *sbh;
	unsigned long mask = NILFS_BUFFER_INHERENT_BITS;

	BUG_ON(folio_test_writeback(dst));

	sbh = folio_buffers(src);
	dbh = folio_buffers(dst);
	if (!dbh)
		dbh = create_empty_buffers(dst, sbh->b_size, 0);

	if (copy_dirty)
		mask |= BIT(BH_Dirty);

	dbufs = dbh;
	do {
		lock_buffer(sbh);
		lock_buffer(dbh);
		dbh->b_state = sbh->b_state & mask;
		dbh->b_blocknr = sbh->b_blocknr;
		dbh->b_bdev = sbh->b_bdev;
		sbh = sbh->b_this_page;
		dbh = dbh->b_this_page;
	} while (dbh != dbufs);

	folio_copy(dst, src);

	if (folio_test_uptodate(src) && !folio_test_uptodate(dst))
		folio_mark_uptodate(dst);
	else if (!folio_test_uptodate(src) && folio_test_uptodate(dst))
		folio_clear_uptodate(dst);
	if (folio_test_mappedtodisk(src) && !folio_test_mappedtodisk(dst))
		folio_set_mappedtodisk(dst);
	else if (!folio_test_mappedtodisk(src) && folio_test_mappedtodisk(dst))
		folio_clear_mappedtodisk(dst);

	do {
		unlock_buffer(sbh);
		unlock_buffer(dbh);
		sbh = sbh->b_this_page;
		dbh = dbh->b_this_page;
	} while (dbh != dbufs);
}

int nilfs_copy_dirty_pages(struct address_space *dmap,
			   struct address_space *smap)
{
	struct folio_batch fbatch;
	unsigned int i;
	pgoff_t index = 0;
	int err = 0;

	folio_batch_init(&fbatch);
repeat:
	if (!filemap_get_folios_tag(smap, &index, (pgoff_t)-1,
				PAGECACHE_TAG_DIRTY, &fbatch))
		return 0;

	for (i = 0; i < folio_batch_count(&fbatch); i++) {
		struct folio *folio = fbatch.folios[i], *dfolio;

		folio_lock(folio);
		if (unlikely(!folio_test_dirty(folio)))
			NILFS_FOLIO_BUG(folio, "inconsistent dirty state");

		dfolio = filemap_grab_folio(dmap, folio->index);
		if (IS_ERR(dfolio)) {
			/* No empty page is added to the page cache */
			folio_unlock(folio);
			err = PTR_ERR(dfolio);
			break;
		}
		if (unlikely(!folio_buffers(folio)))
			NILFS_FOLIO_BUG(folio,
				       "found empty page in dat page cache");

		nilfs_copy_folio(dfolio, folio, true);
		filemap_dirty_folio(folio_mapping(dfolio), dfolio);

		folio_unlock(dfolio);
		folio_put(dfolio);
		folio_unlock(folio);
	}
	folio_batch_release(&fbatch);
	cond_resched();

	if (likely(!err))
		goto repeat;
	return err;
}

/**
 * nilfs_copy_back_pages -- copy back pages to original cache from shadow cache
 * @dmap: destination page cache
 * @smap: source page cache
 *
 * No pages must be added to the cache during this process.
 * This must be ensured by the caller.
 */
void nilfs_copy_back_pages(struct address_space *dmap,
			   struct address_space *smap)
{
	struct folio_batch fbatch;
	unsigned int i, n;
	pgoff_t start = 0;

	folio_batch_init(&fbatch);
repeat:
	n = filemap_get_folios(smap, &start, ~0UL, &fbatch);
	if (!n)
		return;

	for (i = 0; i < folio_batch_count(&fbatch); i++) {
		struct folio *folio = fbatch.folios[i], *dfolio;
		pgoff_t index = folio->index;

		folio_lock(folio);
		dfolio = filemap_lock_folio(dmap, index);
		if (!IS_ERR(dfolio)) {
			/* overwrite existing folio in the destination cache */
			WARN_ON(folio_test_dirty(dfolio));
			nilfs_copy_folio(dfolio, folio, false);
			folio_unlock(dfolio);
			folio_put(dfolio);
			/* Do we not need to remove folio from smap here? */
		} else {
			struct folio *f;

			/* move the folio to the destination cache */
			xa_lock_irq(&smap->i_pages);
			f = __xa_erase(&smap->i_pages, index);
			WARN_ON(folio != f);
			smap->nrpages--;
			xa_unlock_irq(&smap->i_pages);

			xa_lock_irq(&dmap->i_pages);
			f = __xa_store(&dmap->i_pages, index, folio, GFP_NOFS);
			if (unlikely(f)) {
				/* Probably -ENOMEM */
				folio->mapping = NULL;
				folio_put(folio);
			} else {
				folio->mapping = dmap;
				dmap->nrpages++;
				if (folio_test_dirty(folio))
					__xa_set_mark(&dmap->i_pages, index,
							PAGECACHE_TAG_DIRTY);
			}
			xa_unlock_irq(&dmap->i_pages);
		}
		folio_unlock(folio);
	}
	folio_batch_release(&fbatch);
	cond_resched();

	goto repeat;
}

/**
 * nilfs_clear_dirty_pages - discard dirty pages in address space
 * @mapping: address space with dirty pages for discarding
 */
void nilfs_clear_dirty_pages(struct address_space *mapping)
{
	struct folio_batch fbatch;
	unsigned int i;
	pgoff_t index = 0;

	folio_batch_init(&fbatch);

	while (filemap_get_folios_tag(mapping, &index, (pgoff_t)-1,
				PAGECACHE_TAG_DIRTY, &fbatch)) {
		for (i = 0; i < folio_batch_count(&fbatch); i++) {
			struct folio *folio = fbatch.folios[i];

			folio_lock(folio);

			/*
			 * This folio may have been removed from the address
			 * space by truncation or invalidation when the lock
			 * was acquired.  Skip processing in that case.
			 */
			if (likely(folio->mapping == mapping))
				nilfs_clear_folio_dirty(folio);

			folio_unlock(folio);
		}
		folio_batch_release(&fbatch);
		cond_resched();
	}
}

/**
 * nilfs_clear_folio_dirty - discard dirty folio
 * @folio: dirty folio that will be discarded
 */
void nilfs_clear_folio_dirty(struct folio *folio)
{
	struct buffer_head *bh, *head;

	BUG_ON(!folio_test_locked(folio));

	folio_clear_uptodate(folio);
	folio_clear_mappedtodisk(folio);

	head = folio_buffers(folio);
	if (head) {
		const unsigned long clear_bits =
			(BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
			 BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
			 BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected));

		bh = head;
		do {
			lock_buffer(bh);
			set_mask_bits(&bh->b_state, clear_bits, 0);
			unlock_buffer(bh);
		} while (bh = bh->b_this_page, bh != head);
	}

	__nilfs_clear_folio_dirty(folio);
}

unsigned int nilfs_page_count_clean_buffers(struct page *page,
					    unsigned int from, unsigned int to)
{
	unsigned int block_start, block_end;
	struct buffer_head *bh, *head;
	unsigned int nc = 0;

	for (bh = head = page_buffers(page), block_start = 0;
	     bh != head || !block_start;
	     block_start = block_end, bh = bh->b_this_page) {
		block_end = block_start + bh->b_size;
		if (block_end > from && block_start < to && !buffer_dirty(bh))
			nc++;
	}
	return nc;
}

/*
 * NILFS2 needs clear_page_dirty() in the following two cases:
 *
 * 1) For B-tree node pages and data pages of DAT file, NILFS2 clears dirty
 *    flag of pages when it copies back pages from shadow cache to the
 *    original cache.
 *
 * 2) Some B-tree operations like insertion or deletion may dispose buffers
 *    in dirty state, and this needs to cancel the dirty state of their pages.
 */
void __nilfs_clear_folio_dirty(struct folio *folio)
{
	struct address_space *mapping = folio->mapping;

	if (mapping) {
		xa_lock_irq(&mapping->i_pages);
		if (folio_test_dirty(folio)) {
			__xa_clear_mark(&mapping->i_pages, folio->index,
					     PAGECACHE_TAG_DIRTY);
			xa_unlock_irq(&mapping->i_pages);
			folio_clear_dirty_for_io(folio);
			return;
		}
		xa_unlock_irq(&mapping->i_pages);
		return;
	}
	folio_clear_dirty(folio);
}

/**
 * nilfs_find_uncommitted_extent - find extent of uncommitted data
 * @inode: inode
 * @start_blk: start block offset (in)
 * @blkoff: start offset of the found extent (out)
 *
 * This function searches an extent of buffers marked "delayed" which
 * starts from a block offset equal to or larger than @start_blk.  If
 * such an extent was found, this will store the start offset in
 * @blkoff and return its length in blocks.  Otherwise, zero is
 * returned.
 */
unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
					    sector_t start_blk,
					    sector_t *blkoff)
{
	unsigned int i, nr_folios;
	pgoff_t index;
	unsigned long length = 0;
	struct folio_batch fbatch;
	struct folio *folio;

	if (inode->i_mapping->nrpages == 0)
		return 0;

	index = start_blk >> (PAGE_SHIFT - inode->i_blkbits);

	folio_batch_init(&fbatch);

repeat:
	nr_folios = filemap_get_folios_contig(inode->i_mapping, &index, ULONG_MAX,
			&fbatch);
	if (nr_folios == 0)
		return length;

	i = 0;
	do {
		folio = fbatch.folios[i];

		folio_lock(folio);
		if (folio_buffers(folio)) {
			struct buffer_head *bh, *head;
			sector_t b;

			b = folio->index << (PAGE_SHIFT - inode->i_blkbits);
			bh = head = folio_buffers(folio);
			do {
				if (b < start_blk)
					continue;
				if (buffer_delay(bh)) {
					if (length == 0)
						*blkoff = b;
					length++;
				} else if (length > 0) {
					goto out_locked;
				}
			} while (++b, bh = bh->b_this_page, bh != head);
		} else {
			if (length > 0)
				goto out_locked;
		}
		folio_unlock(folio);

	} while (++i < nr_folios);

	folio_batch_release(&fbatch);
	cond_resched();
	goto repeat;

out_locked:
	folio_unlock(folio);
	folio_batch_release(&fbatch);
	return length;
}
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0+
	2	/*
	3	* Buffer/page management specific to NILFS
	4	*
	5	* Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
	6	*
	7	* Written by Ryusuke Konishi and Seiji Kihara.
	8	*/
	9
	10	#include <linux/pagemap.h>
	11	#include <linux/writeback.h>
	12	#include <linux/swap.h>
	13	#include <linux/bitops.h>
	14	#include <linux/page-flags.h>
	15	#include <linux/list.h>
	16	#include <linux/highmem.h>
	17	#include <linux/pagevec.h>
	18	#include <linux/gfp.h>
	19	#include "nilfs.h"
	20	#include "page.h"
	21	#include "mdt.h"
	22
	23
	24	#define NILFS_BUFFER_INHERENT_BITS \
	25	(BIT(BH_Uptodate) \| BIT(BH_Mapped) \| BIT(BH_NILFS_Node) \| \
	26	BIT(BH_NILFS_Volatile) \| BIT(BH_NILFS_Checked))
	27
	28	static struct buffer_head __nilfs_get_folio_block(struct folio folio,
	29	unsigned long block, pgoff_t index, int blkbits,
	30	unsigned long b_state)
	31
	32	{
	33	unsigned long first_block;
	34	struct buffer_head *bh = folio_buffers(folio);
	35
	36	if (!bh)
	37	bh = create_empty_buffers(folio, 1 << blkbits, b_state);
	38
	39	first_block = (unsigned long)index << (PAGE_SHIFT - blkbits);
	40	bh = get_nth_bh(bh, block - first_block);
	41
	42	touch_buffer(bh);
	43	wait_on_buffer(bh);
	44	return bh;
	45	}
	46
	47	struct buffer_head nilfs_grab_buffer(struct inode inode,
	48	struct address_space *mapping,
	49	unsigned long blkoff,
	50	unsigned long b_state)
	51	{
	52	int blkbits = inode->i_blkbits;
	53	pgoff_t index = blkoff >> (PAGE_SHIFT - blkbits);
	54	struct folio *folio;
	55	struct buffer_head *bh;
	56
	57	folio = filemap_grab_folio(mapping, index);
	58	if (IS_ERR(folio))
	59	return NULL;
	60
	61	bh = __nilfs_get_folio_block(folio, blkoff, index, blkbits, b_state);
	62	if (unlikely(!bh)) {
	63	folio_unlock(folio);
	64	folio_put(folio);
	65	return NULL;
	66	}
	67	return bh;
	68	}
	69
	70	/**
	71	* nilfs_forget_buffer - discard dirty state
	72	* @bh: buffer head of the buffer to be discarded
	73	*/
	74	void nilfs_forget_buffer(struct buffer_head *bh)
	75	{
	76	struct folio *folio = bh->b_folio;
	77	const unsigned long clear_bits =
	78	(BIT(BH_Uptodate) \| BIT(BH_Dirty) \| BIT(BH_Mapped) \|
	79	BIT(BH_Async_Write) \| BIT(BH_NILFS_Volatile) \|
	80	BIT(BH_NILFS_Checked) \| BIT(BH_NILFS_Redirected));
	81
	82	lock_buffer(bh);
	83	set_mask_bits(&bh->b_state, clear_bits, 0);
	84	if (nilfs_folio_buffers_clean(folio))
	85	__nilfs_clear_folio_dirty(folio);
	86
	87	bh->b_blocknr = -1;
	88	folio_clear_uptodate(folio);
	89	folio_clear_mappedtodisk(folio);
	90	unlock_buffer(bh);
	91	brelse(bh);
	92	}
	93
	94	/**
	95	* nilfs_copy_buffer -- copy buffer data and flags
	96	* @dbh: destination buffer
	97	* @sbh: source buffer
	98	*/
	99	void nilfs_copy_buffer(struct buffer_head dbh, struct buffer_head sbh)
	100	{
	101	void kaddr0, kaddr1;
	102	unsigned long bits;
	103	struct page spage = sbh->b_page, dpage = dbh->b_page;
	104	struct buffer_head *bh;
	105
	106	kaddr0 = kmap_local_page(spage);
	107	kaddr1 = kmap_local_page(dpage);
	108	memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
	109	kunmap_local(kaddr1);
	110	kunmap_local(kaddr0);
	111
	112	dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
	113	dbh->b_blocknr = sbh->b_blocknr;
	114	dbh->b_bdev = sbh->b_bdev;
	115
	116	bh = dbh;
	117	bits = sbh->b_state & (BIT(BH_Uptodate) \| BIT(BH_Mapped));
	118	while ((bh = bh->b_this_page) != dbh) {
	119	lock_buffer(bh);
	120	bits &= bh->b_state;
	121	unlock_buffer(bh);
	122	}
	123	if (bits & BIT(BH_Uptodate))
	124	SetPageUptodate(dpage);
	125	else
	126	ClearPageUptodate(dpage);
	127	if (bits & BIT(BH_Mapped))
	128	SetPageMappedToDisk(dpage);
	129	else
	130	ClearPageMappedToDisk(dpage);
	131	}
	132
	133	/**
	134	* nilfs_folio_buffers_clean - Check if a folio has dirty buffers or not.
	135	* @folio: Folio to be checked.
	136	*
	137	* nilfs_folio_buffers_clean() returns false if the folio has dirty buffers.
	138	* Otherwise, it returns true.
	139	*/
	140	bool nilfs_folio_buffers_clean(struct folio *folio)
	141	{
	142	struct buffer_head bh, head;
	143
	144	bh = head = folio_buffers(folio);
	145	do {
	146	if (buffer_dirty(bh))
	147	return false;
	148	bh = bh->b_this_page;
	149	} while (bh != head);
	150	return true;
	151	}
	152
	153	void nilfs_folio_bug(struct folio *folio)
	154	{
	155	struct buffer_head bh, head;
	156	struct address_space *m;
	157	unsigned long ino;
	158
	159	if (unlikely(!folio)) {
	160	printk(KERN_CRIT "NILFS_FOLIO_BUG(NULL)\n");
	161	return;
	162	}
	163
	164	m = folio->mapping;
	165	ino = m ? m->host->i_ino : 0;
	166
	167	printk(KERN_CRIT "NILFS_FOLIO_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
	168	"mapping=%p ino=%lu\n",
	169	folio, folio_ref_count(folio),
	170	(unsigned long long)folio->index, folio->flags, m, ino);
	171
	172	head = folio_buffers(folio);
	173	if (head) {
	174	int i = 0;
	175
	176	bh = head;
	177	do {
	178	printk(KERN_CRIT
	179	" BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
	180	i++, bh, atomic_read(&bh->b_count),
	181	(unsigned long long)bh->b_blocknr, bh->b_state);
	182	bh = bh->b_this_page;
	183	} while (bh != head);
	184	}
	185	}
	186
	187	/**
	188	* nilfs_copy_folio -- copy the folio with buffers
	189	* @dst: destination folio
	190	* @src: source folio
	191	* @copy_dirty: flag whether to copy dirty states on the folio's buffer heads.
	192	*
	193	* This function is for both data folios and btnode folios. The dirty flag
	194	* should be treated by caller. The folio must not be under i/o.
	195	* Both src and dst folio must be locked
	196	*/
	197	static void nilfs_copy_folio(struct folio dst, struct folio src,
	198	bool copy_dirty)
	199	{
	200	struct buffer_head dbh, dbufs, *sbh;
	201	unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
	202
	203	BUG_ON(folio_test_writeback(dst));
	204
	205	sbh = folio_buffers(src);
	206	dbh = folio_buffers(dst);
	207	if (!dbh)
	208	dbh = create_empty_buffers(dst, sbh->b_size, 0);
	209
	210	if (copy_dirty)
	211	mask \|= BIT(BH_Dirty);
	212
	213	dbufs = dbh;
	214	do {
	215	lock_buffer(sbh);
	216	lock_buffer(dbh);
	217	dbh->b_state = sbh->b_state & mask;
	218	dbh->b_blocknr = sbh->b_blocknr;
	219	dbh->b_bdev = sbh->b_bdev;
	220	sbh = sbh->b_this_page;
	221	dbh = dbh->b_this_page;
	222	} while (dbh != dbufs);
	223
	224	folio_copy(dst, src);
	225
	226	if (folio_test_uptodate(src) && !folio_test_uptodate(dst))
	227	folio_mark_uptodate(dst);
	228	else if (!folio_test_uptodate(src) && folio_test_uptodate(dst))
	229	folio_clear_uptodate(dst);
	230	if (folio_test_mappedtodisk(src) && !folio_test_mappedtodisk(dst))
	231	folio_set_mappedtodisk(dst);
	232	else if (!folio_test_mappedtodisk(src) && folio_test_mappedtodisk(dst))
	233	folio_clear_mappedtodisk(dst);
	234
	235	do {
	236	unlock_buffer(sbh);
	237	unlock_buffer(dbh);
	238	sbh = sbh->b_this_page;
	239	dbh = dbh->b_this_page;
	240	} while (dbh != dbufs);
	241	}
	242
	243	int nilfs_copy_dirty_pages(struct address_space *dmap,
	244	struct address_space *smap)
	245	{
	246	struct folio_batch fbatch;
	247	unsigned int i;
	248	pgoff_t index = 0;
	249	int err = 0;
	250
	251	folio_batch_init(&fbatch);
	252	repeat:
	253	if (!filemap_get_folios_tag(smap, &index, (pgoff_t)-1,
	254	PAGECACHE_TAG_DIRTY, &fbatch))
	255	return 0;
	256
	257	for (i = 0; i < folio_batch_count(&fbatch); i++) {
	258	struct folio folio = fbatch.folios[i], dfolio;
	259
	260	folio_lock(folio);
	261	if (unlikely(!folio_test_dirty(folio)))
	262	NILFS_FOLIO_BUG(folio, "inconsistent dirty state");
	263
	264	dfolio = filemap_grab_folio(dmap, folio->index);
	265	if (IS_ERR(dfolio)) {
	266	/* No empty page is added to the page cache */
	267	folio_unlock(folio);
	268	err = PTR_ERR(dfolio);
	269	break;
	270	}
	271	if (unlikely(!folio_buffers(folio)))
	272	NILFS_FOLIO_BUG(folio,
	273	"found empty page in dat page cache");
	274
	275	nilfs_copy_folio(dfolio, folio, true);
	276	filemap_dirty_folio(folio_mapping(dfolio), dfolio);
	277
	278	folio_unlock(dfolio);
	279	folio_put(dfolio);
	280	folio_unlock(folio);
	281	}
	282	folio_batch_release(&fbatch);
	283	cond_resched();
	284
	285	if (likely(!err))
	286	goto repeat;
	287	return err;
	288	}
	289
	290	/**
	291	* nilfs_copy_back_pages -- copy back pages to original cache from shadow cache
	292	* @dmap: destination page cache
	293	* @smap: source page cache
	294	*
	295	* No pages must be added to the cache during this process.
	296	* This must be ensured by the caller.
	297	*/
	298	void nilfs_copy_back_pages(struct address_space *dmap,
	299	struct address_space *smap)
	300	{
	301	struct folio_batch fbatch;
	302	unsigned int i, n;
	303	pgoff_t start = 0;
	304
	305	folio_batch_init(&fbatch);
	306	repeat:
	307	n = filemap_get_folios(smap, &start, ~0UL, &fbatch);
	308	if (!n)
	309	return;
	310
	311	for (i = 0; i < folio_batch_count(&fbatch); i++) {
	312	struct folio folio = fbatch.folios[i], dfolio;
	313	pgoff_t index = folio->index;
	314
	315	folio_lock(folio);
	316	dfolio = filemap_lock_folio(dmap, index);
	317	if (!IS_ERR(dfolio)) {
	318	/* overwrite existing folio in the destination cache */
	319	WARN_ON(folio_test_dirty(dfolio));
	320	nilfs_copy_folio(dfolio, folio, false);
	321	folio_unlock(dfolio);
	322	folio_put(dfolio);
	323	/* Do we not need to remove folio from smap here? */
	324	} else {
	325	struct folio *f;
	326
	327	/* move the folio to the destination cache */
	328	xa_lock_irq(&smap->i_pages);
	329	f = __xa_erase(&smap->i_pages, index);
	330	WARN_ON(folio != f);
	331	smap->nrpages--;
	332	xa_unlock_irq(&smap->i_pages);
	333
	334	xa_lock_irq(&dmap->i_pages);
	335	f = __xa_store(&dmap->i_pages, index, folio, GFP_NOFS);
	336	if (unlikely(f)) {
	337	/* Probably -ENOMEM */
	338	folio->mapping = NULL;
	339	folio_put(folio);
	340	} else {
	341	folio->mapping = dmap;
	342	dmap->nrpages++;
	343	if (folio_test_dirty(folio))
	344	__xa_set_mark(&dmap->i_pages, index,
	345	PAGECACHE_TAG_DIRTY);
	346	}
	347	xa_unlock_irq(&dmap->i_pages);
	348	}
	349	folio_unlock(folio);
	350	}
	351	folio_batch_release(&fbatch);
	352	cond_resched();
	353
	354	goto repeat;
	355	}
	356
	357	/**
	358	* nilfs_clear_dirty_pages - discard dirty pages in address space
	359	* @mapping: address space with dirty pages for discarding
	360	*/
	361	void nilfs_clear_dirty_pages(struct address_space *mapping)
	362	{
	363	struct folio_batch fbatch;
	364	unsigned int i;
	365	pgoff_t index = 0;
	366
	367	folio_batch_init(&fbatch);
	368
	369	while (filemap_get_folios_tag(mapping, &index, (pgoff_t)-1,
	370	PAGECACHE_TAG_DIRTY, &fbatch)) {
	371	for (i = 0; i < folio_batch_count(&fbatch); i++) {
	372	struct folio *folio = fbatch.folios[i];
	373
	374	folio_lock(folio);
	375
	376	/*
	377	* This folio may have been removed from the address
	378	* space by truncation or invalidation when the lock
	379	* was acquired. Skip processing in that case.
	380	*/
	381	if (likely(folio->mapping == mapping))
	382	nilfs_clear_folio_dirty(folio);
	383
	384	folio_unlock(folio);
	385	}
	386	folio_batch_release(&fbatch);
	387	cond_resched();
	388	}
	389	}
	390
	391	/**
	392	* nilfs_clear_folio_dirty - discard dirty folio
	393	* @folio: dirty folio that will be discarded
	394	*/
	395	void nilfs_clear_folio_dirty(struct folio *folio)
	396	{
	397	struct buffer_head bh, head;
	398
	399	BUG_ON(!folio_test_locked(folio));
	400
	401	folio_clear_uptodate(folio);
	402	folio_clear_mappedtodisk(folio);
	403
	404	head = folio_buffers(folio);
	405	if (head) {
	406	const unsigned long clear_bits =
	407	(BIT(BH_Uptodate) \| BIT(BH_Dirty) \| BIT(BH_Mapped) \|
	408	BIT(BH_Async_Write) \| BIT(BH_NILFS_Volatile) \|
	409	BIT(BH_NILFS_Checked) \| BIT(BH_NILFS_Redirected));
	410
	411	bh = head;
	412	do {
	413	lock_buffer(bh);
	414	set_mask_bits(&bh->b_state, clear_bits, 0);
	415	unlock_buffer(bh);
	416	} while (bh = bh->b_this_page, bh != head);
	417	}
	418
	419	__nilfs_clear_folio_dirty(folio);
	420	}
	421
	422	unsigned int nilfs_page_count_clean_buffers(struct page *page,
	423	unsigned int from, unsigned int to)
	424	{
	425	unsigned int block_start, block_end;
	426	struct buffer_head bh, head;
	427	unsigned int nc = 0;
	428
	429	for (bh = head = page_buffers(page), block_start = 0;
	430	bh != head \|\| !block_start;
	431	block_start = block_end, bh = bh->b_this_page) {
	432	block_end = block_start + bh->b_size;
	433	if (block_end > from && block_start < to && !buffer_dirty(bh))
	434	nc++;
	435	}
	436	return nc;
	437	}
	438
	439	/*
	440	* NILFS2 needs clear_page_dirty() in the following two cases:
	441	*
	442	* 1) For B-tree node pages and data pages of DAT file, NILFS2 clears dirty
	443	* flag of pages when it copies back pages from shadow cache to the
	444	* original cache.
	445	*
	446	* 2) Some B-tree operations like insertion or deletion may dispose buffers
	447	* in dirty state, and this needs to cancel the dirty state of their pages.
	448	*/
	449	void __nilfs_clear_folio_dirty(struct folio *folio)
	450	{
	451	struct address_space *mapping = folio->mapping;
	452
	453	if (mapping) {
	454	xa_lock_irq(&mapping->i_pages);
	455	if (folio_test_dirty(folio)) {
	456	__xa_clear_mark(&mapping->i_pages, folio->index,
	457	PAGECACHE_TAG_DIRTY);
	458	xa_unlock_irq(&mapping->i_pages);
	459	folio_clear_dirty_for_io(folio);
	460	return;
	461	}
	462	xa_unlock_irq(&mapping->i_pages);
	463	return;
	464	}
	465	folio_clear_dirty(folio);
	466	}
	467
	468	/**
	469	* nilfs_find_uncommitted_extent - find extent of uncommitted data
	470	* @inode: inode
	471	* @start_blk: start block offset (in)
	472	* @blkoff: start offset of the found extent (out)
	473	*
	474	* This function searches an extent of buffers marked "delayed" which
	475	* starts from a block offset equal to or larger than @start_blk. If
	476	* such an extent was found, this will store the start offset in
	477	* @blkoff and return its length in blocks. Otherwise, zero is
	478	* returned.
	479	*/
	480	unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
	481	sector_t start_blk,
	482	sector_t *blkoff)
	483	{
	484	unsigned int i, nr_folios;
	485	pgoff_t index;
	486	unsigned long length = 0;
	487	struct folio_batch fbatch;
	488	struct folio *folio;
	489
	490	if (inode->i_mapping->nrpages == 0)
	491	return 0;
	492
	493	index = start_blk >> (PAGE_SHIFT - inode->i_blkbits);
	494
	495	folio_batch_init(&fbatch);
	496
	497	repeat:
	498	nr_folios = filemap_get_folios_contig(inode->i_mapping, &index, ULONG_MAX,
	499	&fbatch);
	500	if (nr_folios == 0)
	501	return length;
	502
	503	i = 0;
	504	do {
	505	folio = fbatch.folios[i];
	506
	507	folio_lock(folio);
	508	if (folio_buffers(folio)) {
	509	struct buffer_head bh, head;
	510	sector_t b;
	511
	512	b = folio->index << (PAGE_SHIFT - inode->i_blkbits);
	513	bh = head = folio_buffers(folio);
	514	do {
	515	if (b < start_blk)
	516	continue;
	517	if (buffer_delay(bh)) {
	518	if (length == 0)
	519	*blkoff = b;
	520	length++;
	521	} else if (length > 0) {
	522	goto out_locked;
	523	}
	524	} while (++b, bh = bh->b_this_page, bh != head);
	525	} else {
	526	if (length > 0)
	527	goto out_locked;
	528	}
	529	folio_unlock(folio);
	530
	531	} while (++i < nr_folios);
	532
	533	folio_batch_release(&fbatch);
	534	cond_resched();
	535	goto repeat;
	536
	537	out_locked:
	538	folio_unlock(folio);
	539	folio_batch_release(&fbatch);
	540	return length;
	541	}