[people/ms/linux.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_page_block(struct page *page, unsigned long block, pgoff_t index,
		       int blkbits, unsigned long b_state)

{
	unsigned long first_block;
	struct buffer_head *bh;

	if (!page_has_buffers(page))
		create_empty_buffers(page, 1 << blkbits, b_state);

	first_block = (unsigned long)index << (PAGE_SHIFT - blkbits);
	bh = nilfs_page_get_nth_block(page, 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 page *page;
	struct buffer_head *bh;

	page = grab_cache_page(mapping, index);
	if (unlikely(!page))
		return NULL;

	bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state);
	if (unlikely(!bh)) {
		unlock_page(page);
		put_page(page);
		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 page *page = bh->b_page;
	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_page_buffers_clean(page))
		__nilfs_clear_page_dirty(page);

	bh->b_blocknr = -1;
	ClearPageUptodate(page);
	ClearPageMappedToDisk(page);
	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_atomic(spage);
	kaddr1 = kmap_atomic(dpage);
	memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
	kunmap_atomic(kaddr1);
	kunmap_atomic(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_page_buffers_clean - check if a page has dirty buffers or not.
 * @page: page to be checked
 *
 * nilfs_page_buffers_clean() returns zero if the page has dirty buffers.
 * Otherwise, it returns non-zero value.
 */
int nilfs_page_buffers_clean(struct page *page)
{
	struct buffer_head *bh, *head;

	bh = head = page_buffers(page);
	do {
		if (buffer_dirty(bh))
			return 0;
		bh = bh->b_this_page;
	} while (bh != head);
	return 1;
}

void nilfs_page_bug(struct page *page)
{
	struct address_space *m;
	unsigned long ino;

	if (unlikely(!page)) {
		printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
		return;
	}

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

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

	if (page_has_buffers(page)) {
		struct buffer_head *bh, *head;
		int i = 0;

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

	BUG_ON(PageWriteback(dst));

	sbh = page_buffers(src);
	if (!page_has_buffers(dst))
		create_empty_buffers(dst, sbh->b_size, 0);

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

	dbh = dbufs = page_buffers(dst);
	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);

	copy_highpage(dst, src);

	if (PageUptodate(src) && !PageUptodate(dst))
		SetPageUptodate(dst);
	else if (!PageUptodate(src) && PageUptodate(dst))
		ClearPageUptodate(dst);
	if (PageMappedToDisk(src) && !PageMappedToDisk(dst))
		SetPageMappedToDisk(dst);
	else if (!PageMappedToDisk(src) && PageMappedToDisk(dst))
		ClearPageMappedToDisk(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 pagevec pvec;
	unsigned int i;
	pgoff_t index = 0;
	int err = 0;

	pagevec_init(&pvec);
repeat:
	if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY))
		return 0;

	for (i = 0; i < pagevec_count(&pvec); i++) {
		struct page *page = pvec.pages[i], *dpage;

		lock_page(page);
		if (unlikely(!PageDirty(page)))
			NILFS_PAGE_BUG(page, "inconsistent dirty state");

		dpage = grab_cache_page(dmap, page->index);
		if (unlikely(!dpage)) {
			/* No empty page is added to the page cache */
			err = -ENOMEM;
			unlock_page(page);
			break;
		}
		if (unlikely(!page_has_buffers(page)))
			NILFS_PAGE_BUG(page,
				       "found empty page in dat page cache");

		nilfs_copy_page(dpage, page, 1);
		__set_page_dirty_nobuffers(dpage);

		unlock_page(dpage);
		put_page(dpage);
		unlock_page(page);
	}
	pagevec_release(&pvec);
	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 pagevec pvec;
	unsigned int i, n;
	pgoff_t index = 0;

	pagevec_init(&pvec);
repeat:
	n = pagevec_lookup(&pvec, smap, &index);
	if (!n)
		return;

	for (i = 0; i < pagevec_count(&pvec); i++) {
		struct page *page = pvec.pages[i], *dpage;
		pgoff_t offset = page->index;

		lock_page(page);
		dpage = find_lock_page(dmap, offset);
		if (dpage) {
			/* overwrite existing page in the destination cache */
			WARN_ON(PageDirty(dpage));
			nilfs_copy_page(dpage, page, 0);
			unlock_page(dpage);
			put_page(dpage);
			/* Do we not need to remove page from smap here? */
		} else {
			struct page *p;

			/* move the page to the destination cache */
			xa_lock_irq(&smap->i_pages);
			p = __xa_erase(&smap->i_pages, offset);
			WARN_ON(page != p);
			smap->nrpages--;
			xa_unlock_irq(&smap->i_pages);

			xa_lock_irq(&dmap->i_pages);
			p = __xa_store(&dmap->i_pages, offset, page, GFP_NOFS);
			if (unlikely(p)) {
				/* Probably -ENOMEM */
				page->mapping = NULL;
				put_page(page);
			} else {
				page->mapping = dmap;
				dmap->nrpages++;
				if (PageDirty(page))
					__xa_set_mark(&dmap->i_pages, offset,
							PAGECACHE_TAG_DIRTY);
			}
			xa_unlock_irq(&dmap->i_pages);
		}
		unlock_page(page);
	}
	pagevec_release(&pvec);
	cond_resched();

	goto repeat;
}

/**
 * nilfs_clear_dirty_pages - discard dirty pages in address space
 * @mapping: address space with dirty pages for discarding
 * @silent: suppress [true] or print [false] warning messages
 */
void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent)
{
	struct pagevec pvec;
	unsigned int i;
	pgoff_t index = 0;

	pagevec_init(&pvec);

	while (pagevec_lookup_tag(&pvec, mapping, &index,
					PAGECACHE_TAG_DIRTY)) {
		for (i = 0; i < pagevec_count(&pvec); i++) {
			struct page *page = pvec.pages[i];

			lock_page(page);
			nilfs_clear_dirty_page(page, silent);
			unlock_page(page);
		}
		pagevec_release(&pvec);
		cond_resched();
	}
}

/**
 * nilfs_clear_dirty_page - discard dirty page
 * @page: dirty page that will be discarded
 * @silent: suppress [true] or print [false] warning messages
 */
void nilfs_clear_dirty_page(struct page *page, bool silent)
{
	struct inode *inode = page->mapping->host;
	struct super_block *sb = inode->i_sb;

	BUG_ON(!PageLocked(page));

	if (!silent)
		nilfs_warn(sb, "discard dirty page: offset=%lld, ino=%lu",
			   page_offset(page), inode->i_ino);

	ClearPageUptodate(page);
	ClearPageMappedToDisk(page);

	if (page_has_buffers(page)) {
		struct buffer_head *bh, *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 = page_buffers(page);
		do {
			lock_buffer(bh);
			if (!silent)
				nilfs_warn(sb,
					   "discard dirty block: blocknr=%llu, size=%zu",
					   (u64)bh->b_blocknr, bh->b_size);

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

	__nilfs_clear_page_dirty(page);
}

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.
 */
int __nilfs_clear_page_dirty(struct page *page)
{
	struct address_space *mapping = page->mapping;

	if (mapping) {
		xa_lock_irq(&mapping->i_pages);
		if (test_bit(PG_dirty, &page->flags)) {
			__xa_clear_mark(&mapping->i_pages, page_index(page),
					     PAGECACHE_TAG_DIRTY);
			xa_unlock_irq(&mapping->i_pages);
			return clear_page_dirty_for_io(page);
		}
		xa_unlock_irq(&mapping->i_pages);
		return 0;
	}
	return TestClearPageDirty(page);
}

/**
 * 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;
	pgoff_t index;
	unsigned int nblocks_in_page;
	unsigned long length = 0;
	sector_t b;
	struct pagevec pvec;
	struct page *page;

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

	index = start_blk >> (PAGE_SHIFT - inode->i_blkbits);
	nblocks_in_page = 1U << (PAGE_SHIFT - inode->i_blkbits);

	pagevec_init(&pvec);

repeat:
	pvec.nr = find_get_pages_contig(inode->i_mapping, index, PAGEVEC_SIZE,
					pvec.pages);
	if (pvec.nr == 0)
		return length;

	if (length > 0 && pvec.pages[0]->index > index)
		goto out;

	b = pvec.pages[0]->index << (PAGE_SHIFT - inode->i_blkbits);
	i = 0;
	do {
		page = pvec.pages[i];

		lock_page(page);
		if (page_has_buffers(page)) {
			struct buffer_head *bh, *head;

			bh = head = page_buffers(page);
			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;

			b += nblocks_in_page;
		}
		unlock_page(page);

	} while (++i < pagevec_count(&pvec));

	index = page->index + 1;
	pagevec_release(&pvec);
	cond_resched();
	goto repeat;

out_locked:
	unlock_page(page);
out:
	pagevec_release(&pvec);
	return length;
}
Commit	Line	Data
ae98043f	1	// SPDX-License-Identifier: GPL-2.0+
0bd49f94	2	/*
94ee1d91	3	* Buffer/page management specific to NILFS
0bd49f94 RK	4	*
	5	* Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
	6	*
4b420ab4	7	* Written by Ryusuke Konishi and Seiji Kihara.
0bd49f94 RK	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>
5a0e3ad6	18	#include <linux/gfp.h>
0bd49f94 RK	19	#include "nilfs.h"
	20	#include "page.h"
	21	#include "mdt.h"
	22
	23
4ce5c342 RK	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))
0bd49f94 RK	27
	28	static struct buffer_head *
	29	__nilfs_get_page_block(struct page *page, unsigned long block, pgoff_t index,
	30	int blkbits, unsigned long b_state)
	31
	32	{
	33	unsigned long first_block;
	34	struct buffer_head *bh;
	35
	36	if (!page_has_buffers(page))
	37	create_empty_buffers(page, 1 << blkbits, b_state);
	38
09cbfeaf	39	first_block = (unsigned long)index << (PAGE_SHIFT - blkbits);
0bd49f94 RK	40	bh = nilfs_page_get_nth_block(page, block - first_block);
	41
	42	touch_buffer(bh);
	43	wait_on_buffer(bh);
	44	return bh;
	45	}
	46
0bd49f94 RK	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;
09cbfeaf	53	pgoff_t index = blkoff >> (PAGE_SHIFT - blkbits);
c1c1d709 RK	54	struct page *page;
c1c1d709 RK	55	struct buffer_head *bh;
0bd49f94 RK	56
	57	page = grab_cache_page(mapping, index);
	58	if (unlikely(!page))
	59	return NULL;
	60
	61	bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state);
	62	if (unlikely(!bh)) {
	63	unlock_page(page);
09cbfeaf	64	put_page(page);
0bd49f94 RK	65	return NULL;
0bd49f94 RK	66	}
0bd49f94 RK	67	return bh;
	68	}
	69
	70	/**
	71	* nilfs_forget_buffer - discard dirty state
0bd49f94 RK	72	* @bh: buffer head of the buffer to be discarded
	73	*/
	74	void nilfs_forget_buffer(struct buffer_head *bh)
	75	{
	76	struct page *page = bh->b_page;
ead8ecff	77	const unsigned long clear_bits =
4ce5c342 RK	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));
0bd49f94 RK	81
0bd49f94 RK	82	lock_buffer(bh);
ead8ecff	83	set_mask_bits(&bh->b_state, clear_bits, 0);
84338237	84	if (nilfs_page_buffers_clean(page))
0bd49f94 RK	85	__nilfs_clear_page_dirty(page);
0bd49f94 RK	86
0bd49f94 RK	87	bh->b_blocknr = -1;
	88	ClearPageUptodate(page);
	89	ClearPageMappedToDisk(page);
	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
7b9c0976 CW	106	kaddr0 = kmap_atomic(spage);
7b9c0976 CW	107	kaddr1 = kmap_atomic(dpage);
0bd49f94	108	memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
7b9c0976 CW	109	kunmap_atomic(kaddr1);
7b9c0976 CW	110	kunmap_atomic(kaddr0);
0bd49f94 RK	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;
4ce5c342	117	bits = sbh->b_state & (BIT(BH_Uptodate) \| BIT(BH_Mapped));
0bd49f94 RK	118	while ((bh = bh->b_this_page) != dbh) {
	119	lock_buffer(bh);
	120	bits &= bh->b_state;
	121	unlock_buffer(bh);
	122	}
4ce5c342	123	if (bits & BIT(BH_Uptodate))
0bd49f94 RK	124	SetPageUptodate(dpage);
	125	else
	126	ClearPageUptodate(dpage);
4ce5c342	127	if (bits & BIT(BH_Mapped))
0bd49f94 RK	128	SetPageMappedToDisk(dpage);
	129	else
	130	ClearPageMappedToDisk(dpage);
	131	}
	132
	133	/**
	134	* nilfs_page_buffers_clean - check if a page has dirty buffers or not.
	135	* @page: page to be checked
	136	*
	137	* nilfs_page_buffers_clean() returns zero if the page has dirty buffers.
	138	* Otherwise, it returns non-zero value.
	139	*/
	140	int nilfs_page_buffers_clean(struct page *page)
	141	{
	142	struct buffer_head bh, head;
	143
	144	bh = head = page_buffers(page);
	145	do {
	146	if (buffer_dirty(bh))
	147	return 0;
	148	bh = bh->b_this_page;
	149	} while (bh != head);
	150	return 1;
	151	}
	152
	153	void nilfs_page_bug(struct page *page)
	154	{
	155	struct address_space *m;
aa405b1f	156	unsigned long ino;
0bd49f94 RK	157
	158	if (unlikely(!page)) {
	159	printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
	160	return;
	161	}
	162
	163	m = page->mapping;
aa405b1f RK	164	ino = m ? m->host->i_ino : 0;
aa405b1f RK	165
0bd49f94 RK	166	printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
0bd49f94 RK	167	"mapping=%p ino=%lu\n",
fe896d18	168	page, page_ref_count(page),
0bd49f94 RK	169	(unsigned long long)page->index, page->flags, m, ino);
	170
	171	if (page_has_buffers(page)) {
	172	struct buffer_head bh, head;
	173	int i = 0;
	174
	175	bh = head = page_buffers(page);
	176	do {
	177	printk(KERN_CRIT
	178	" BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
	179	i++, bh, atomic_read(&bh->b_count),
	180	(unsigned long long)bh->b_blocknr, bh->b_state);
	181	bh = bh->b_this_page;
	182	} while (bh != head);
	183	}
	184	}
	185
0bd49f94 RK	186	/**
	187	* nilfs_copy_page -- copy the page with buffers
	188	* @dst: destination page
	189	* @src: source page
	190	* @copy_dirty: flag whether to copy dirty states on the page's buffer heads.
	191	*
7a65004b	192	* This function is for both data pages and btnode pages. The dirty flag
0bd49f94 RK	193	* should be treated by caller. The page must not be under i/o.
	194	* Both src and dst page must be locked
	195	*/
	196	static void nilfs_copy_page(struct page dst, struct page src, int copy_dirty)
	197	{
e1ce8a97	198	struct buffer_head dbh, dbufs, *sbh;
0bd49f94 RK	199	unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
	200
	201	BUG_ON(PageWriteback(dst));
	202
e1ce8a97	203	sbh = page_buffers(src);
0bd49f94 RK	204	if (!page_has_buffers(dst))
	205	create_empty_buffers(dst, sbh->b_size, 0);
	206
	207	if (copy_dirty)
4ce5c342	208	mask \|= BIT(BH_Dirty);
0bd49f94 RK	209
	210	dbh = dbufs = page_buffers(dst);
	211	do {
	212	lock_buffer(sbh);
	213	lock_buffer(dbh);
	214	dbh->b_state = sbh->b_state & mask;
	215	dbh->b_blocknr = sbh->b_blocknr;
	216	dbh->b_bdev = sbh->b_bdev;
	217	sbh = sbh->b_this_page;
	218	dbh = dbh->b_this_page;
	219	} while (dbh != dbufs);
	220
	221	copy_highpage(dst, src);
	222
	223	if (PageUptodate(src) && !PageUptodate(dst))
	224	SetPageUptodate(dst);
	225	else if (!PageUptodate(src) && PageUptodate(dst))
	226	ClearPageUptodate(dst);
	227	if (PageMappedToDisk(src) && !PageMappedToDisk(dst))
	228	SetPageMappedToDisk(dst);
	229	else if (!PageMappedToDisk(src) && PageMappedToDisk(dst))
	230	ClearPageMappedToDisk(dst);
	231
	232	do {
	233	unlock_buffer(sbh);
	234	unlock_buffer(dbh);
	235	sbh = sbh->b_this_page;
	236	dbh = dbh->b_this_page;
	237	} while (dbh != dbufs);
	238	}
	239
	240	int nilfs_copy_dirty_pages(struct address_space *dmap,
	241	struct address_space *smap)
	242	{
	243	struct pagevec pvec;
	244	unsigned int i;
	245	pgoff_t index = 0;
	246	int err = 0;
	247
86679820	248	pagevec_init(&pvec);
0bd49f94	249	repeat:
67fd707f	250	if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY))
0bd49f94 RK	251	return 0;
	252
	253	for (i = 0; i < pagevec_count(&pvec); i++) {
	254	struct page page = pvec.pages[i], dpage;
	255
	256	lock_page(page);
	257	if (unlikely(!PageDirty(page)))
	258	NILFS_PAGE_BUG(page, "inconsistent dirty state");
	259
	260	dpage = grab_cache_page(dmap, page->index);
	261	if (unlikely(!dpage)) {
	262	/* No empty page is added to the page cache */
	263	err = -ENOMEM;
	264	unlock_page(page);
	265	break;
	266	}
	267	if (unlikely(!page_has_buffers(page)))
	268	NILFS_PAGE_BUG(page,
	269	"found empty page in dat page cache");
	270
	271	nilfs_copy_page(dpage, page, 1);
	272	__set_page_dirty_nobuffers(dpage);
	273
	274	unlock_page(dpage);
09cbfeaf	275	put_page(dpage);
0bd49f94 RK	276	unlock_page(page);
	277	}
	278	pagevec_release(&pvec);
	279	cond_resched();
	280
	281	if (likely(!err))
	282	goto repeat;
	283	return err;
	284	}
	285
	286	/**
7a65004b	287	* nilfs_copy_back_pages -- copy back pages to original cache from shadow cache
0bd49f94 RK	288	* @dmap: destination page cache
	289	* @smap: source page cache
	290	*
f611ff63	291	* No pages must be added to the cache during this process.
0bd49f94 RK	292	* This must be ensured by the caller.
	293	*/
	294	void nilfs_copy_back_pages(struct address_space *dmap,
	295	struct address_space *smap)
	296	{
	297	struct pagevec pvec;
	298	unsigned int i, n;
	299	pgoff_t index = 0;
0bd49f94	300
86679820	301	pagevec_init(&pvec);
0bd49f94	302	repeat:
397162ff	303	n = pagevec_lookup(&pvec, smap, &index);
0bd49f94 RK	304	if (!n)
0bd49f94 RK	305	return;
0bd49f94 RK	306
	307	for (i = 0; i < pagevec_count(&pvec); i++) {
	308	struct page page = pvec.pages[i], dpage;
	309	pgoff_t offset = page->index;
	310
	311	lock_page(page);
	312	dpage = find_lock_page(dmap, offset);
	313	if (dpage) {
f611ff63	314	/* overwrite existing page in the destination cache */
1f5abe7e	315	WARN_ON(PageDirty(dpage));
0bd49f94 RK	316	nilfs_copy_page(dpage, page, 0);
0bd49f94 RK	317	unlock_page(dpage);
09cbfeaf	318	put_page(dpage);
f611ff63	319	/* Do we not need to remove page from smap here? */
0bd49f94	320	} else {
f611ff63	321	struct page *p;
0bd49f94 RK	322
0bd49f94 RK	323	/* move the page to the destination cache */
b93b0163	324	xa_lock_irq(&smap->i_pages);
f611ff63 MW	325	p = __xa_erase(&smap->i_pages, offset);
f611ff63 MW	326	WARN_ON(page != p);
0bd49f94	327	smap->nrpages--;
b93b0163	328	xa_unlock_irq(&smap->i_pages);
0bd49f94	329
b93b0163	330	xa_lock_irq(&dmap->i_pages);
f611ff63 MW	331	p = __xa_store(&dmap->i_pages, offset, page, GFP_NOFS);
	332	if (unlikely(p)) {
	333	/* Probably -ENOMEM */
0bd49f94	334	page->mapping = NULL;
f611ff63	335	put_page(page);
0bd49f94 RK	336	} else {
	337	page->mapping = dmap;
	338	dmap->nrpages++;
	339	if (PageDirty(page))
f611ff63 MW	340	__xa_set_mark(&dmap->i_pages, offset,
f611ff63 MW	341	PAGECACHE_TAG_DIRTY);
0bd49f94	342	}
b93b0163	343	xa_unlock_irq(&dmap->i_pages);
0bd49f94 RK	344	}
	345	unlock_page(page);
	346	}
	347	pagevec_release(&pvec);
	348	cond_resched();
	349
	350	goto repeat;
	351	}
	352
8c26c4e2 VD	353	/**
	354	* nilfs_clear_dirty_pages - discard dirty pages in address space
	355	* @mapping: address space with dirty pages for discarding
	356	* @silent: suppress [true] or print [false] warning messages
	357	*/
	358	void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent)
0bd49f94 RK	359	{
	360	struct pagevec pvec;
	361	unsigned int i;
	362	pgoff_t index = 0;
	363
86679820	364	pagevec_init(&pvec);
0bd49f94	365
67fd707f JK	366	while (pagevec_lookup_tag(&pvec, mapping, &index,
67fd707f JK	367	PAGECACHE_TAG_DIRTY)) {
0bd49f94 RK	368	for (i = 0; i < pagevec_count(&pvec); i++) {
0bd49f94 RK	369	struct page *page = pvec.pages[i];
0bd49f94 RK	370
0bd49f94 RK	371	lock_page(page);
8c26c4e2	372	nilfs_clear_dirty_page(page, silent);
0bd49f94 RK	373	unlock_page(page);
	374	}
	375	pagevec_release(&pvec);
	376	cond_resched();
	377	}
	378	}
	379
8c26c4e2 VD	380	/**
	381	* nilfs_clear_dirty_page - discard dirty page
	382	* @page: dirty page that will be discarded
	383	* @silent: suppress [true] or print [false] warning messages
	384	*/
	385	void nilfs_clear_dirty_page(struct page *page, bool silent)
	386	{
	387	struct inode *inode = page->mapping->host;
	388	struct super_block *sb = inode->i_sb;
	389
dc33f5f3	390	BUG_ON(!PageLocked(page));
8c26c4e2	391
d6517deb	392	if (!silent)
a1d0747a JP	393	nilfs_warn(sb, "discard dirty page: offset=%lld, ino=%lu",
a1d0747a JP	394	page_offset(page), inode->i_ino);
8c26c4e2 VD	395
	396	ClearPageUptodate(page);
	397	ClearPageMappedToDisk(page);
	398
	399	if (page_has_buffers(page)) {
	400	struct buffer_head bh, head;
ead8ecff	401	const unsigned long clear_bits =
4ce5c342 RK	402	(BIT(BH_Uptodate) \| BIT(BH_Dirty) \| BIT(BH_Mapped) \|
	403	BIT(BH_Async_Write) \| BIT(BH_NILFS_Volatile) \|
	404	BIT(BH_NILFS_Checked) \| BIT(BH_NILFS_Redirected));
8c26c4e2 VD	405
	406	bh = head = page_buffers(page);
	407	do {
	408	lock_buffer(bh);
d6517deb	409	if (!silent)
a1d0747a JP	410	nilfs_warn(sb,
	411	"discard dirty block: blocknr=%llu, size=%zu",
	412	(u64)bh->b_blocknr, bh->b_size);
d6517deb	413
ead8ecff	414	set_mask_bits(&bh->b_state, clear_bits, 0);
8c26c4e2 VD	415	unlock_buffer(bh);
	416	} while (bh = bh->b_this_page, bh != head);
	417	}
	418
	419	__nilfs_clear_page_dirty(page);
	420	}
	421
0c6c44cb RK	422	unsigned int nilfs_page_count_clean_buffers(struct page *page,
0c6c44cb RK	423	unsigned int from, unsigned int to)
0bd49f94	424	{
0c6c44cb	425	unsigned int block_start, block_end;
0bd49f94	426	struct buffer_head bh, head;
0c6c44cb	427	unsigned int nc = 0;
0bd49f94 RK	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	}
ae53a0a2	438
0bd49f94 RK	439	/*
	440	* NILFS2 needs clear_page_dirty() in the following two cases:
	441	*
e897be17 RK	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.
0bd49f94 RK	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	int __nilfs_clear_page_dirty(struct page *page)
	450	{
	451	struct address_space *mapping = page->mapping;
	452
	453	if (mapping) {
b93b0163	454	xa_lock_irq(&mapping->i_pages);
0bd49f94	455	if (test_bit(PG_dirty, &page->flags)) {
f611ff63	456	__xa_clear_mark(&mapping->i_pages, page_index(page),
0bd49f94	457	PAGECACHE_TAG_DIRTY);
b93b0163	458	xa_unlock_irq(&mapping->i_pages);
0bd49f94 RK	459	return clear_page_dirty_for_io(page);
0bd49f94 RK	460	}
b93b0163	461	xa_unlock_irq(&mapping->i_pages);
0bd49f94 RK	462	return 0;
	463	}
	464	return TestClearPageDirty(page);
	465	}
622daaff RK	466
	467	/**
	468	* nilfs_find_uncommitted_extent - find extent of uncommitted data
	469	* @inode: inode
	470	* @start_blk: start block offset (in)
	471	* @blkoff: start offset of the found extent (out)
	472	*
	473	* This function searches an extent of buffers marked "delayed" which
	474	* starts from a block offset equal to or larger than @start_blk. If
	475	* such an extent was found, this will store the start offset in
	476	* @blkoff and return its length in blocks. Otherwise, zero is
	477	* returned.
	478	*/
	479	unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
	480	sector_t start_blk,
	481	sector_t *blkoff)
	482	{
	483	unsigned int i;
	484	pgoff_t index;
	485	unsigned int nblocks_in_page;
	486	unsigned long length = 0;
	487	sector_t b;
	488	struct pagevec pvec;
	489	struct page *page;
	490
	491	if (inode->i_mapping->nrpages == 0)
	492	return 0;
	493
09cbfeaf KS	494	index = start_blk >> (PAGE_SHIFT - inode->i_blkbits);
09cbfeaf KS	495	nblocks_in_page = 1U << (PAGE_SHIFT - inode->i_blkbits);
622daaff	496
86679820	497	pagevec_init(&pvec);
622daaff RK	498
	499	repeat:
	500	pvec.nr = find_get_pages_contig(inode->i_mapping, index, PAGEVEC_SIZE,
	501	pvec.pages);
	502	if (pvec.nr == 0)
	503	return length;
	504
	505	if (length > 0 && pvec.pages[0]->index > index)
	506	goto out;
	507
09cbfeaf	508	b = pvec.pages[0]->index << (PAGE_SHIFT - inode->i_blkbits);
622daaff RK	509	i = 0;
	510	do {
	511	page = pvec.pages[i];
	512
	513	lock_page(page);
	514	if (page_has_buffers(page)) {
	515	struct buffer_head bh, head;
	516
	517	bh = head = page_buffers(page);
	518	do {
	519	if (b < start_blk)
	520	continue;
	521	if (buffer_delay(bh)) {
	522	if (length == 0)
	523	*blkoff = b;
	524	length++;
	525	} else if (length > 0) {
	526	goto out_locked;
	527	}
	528	} while (++b, bh = bh->b_this_page, bh != head);
	529	} else {
	530	if (length > 0)
	531	goto out_locked;
	532
	533	b += nblocks_in_page;
	534	}
	535	unlock_page(page);
	536
	537	} while (++i < pagevec_count(&pvec));
	538
	539	index = page->index + 1;
	540	pagevec_release(&pvec);
	541	cond_resched();
	542	goto repeat;
	543
	544	out_locked:
	545	unlock_page(page);
	546	out:
	547	pagevec_release(&pvec);
	548	return length;
	549	}