[linux.git] / fs / nilfs2 / page.c

/*
 * page.c - buffer/page management specific to NILFS
 *
 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Written by Ryusuke Konishi <[email protected]>,
 *            Seiji Kihara <[email protected]>.
 */

#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  \
	((1UL << BH_Uptodate) | (1UL << BH_Mapped) | (1UL << BH_NILFS_Node) | \
	 (1UL << BH_NILFS_Volatile) | (1UL << 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
 * @inode: owner inode of the buffer
 * @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 =
		(1 << BH_Uptodate | 1 << BH_Dirty | 1 << BH_Mapped |
		 1 << BH_Async_Write | 1 << BH_NILFS_Volatile |
		 1 << BH_NILFS_Checked | 1 << 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 & ((1UL << BH_Uptodate) | (1UL << BH_Mapped));
	while ((bh = bh->b_this_page) != dbh) {
		lock_buffer(bh);
		bits &= bh->b_state;
		unlock_buffer(bh);
	}
	if (bits & (1UL << BH_Uptodate))
		SetPageUptodate(dpage);
	else
		ClearPageUptodate(dpage);
	if (bits & (1UL << 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, *sbufs;
	unsigned long mask = NILFS_BUFFER_INHERENT_BITS;

	BUG_ON(PageWriteback(dst));

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

	if (copy_dirty)
		mask |= (1UL << 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, 0);
repeat:
	if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY,
				PAGEVEC_SIZE))
		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 no 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;
	int err;

	pagevec_init(&pvec, 0);
repeat:
	n = pagevec_lookup(&pvec, smap, index, PAGEVEC_SIZE);
	if (!n)
		return;
	index = pvec.pages[n - 1]->index + 1;

	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) {
			/* override existing page on the destination cache */
			WARN_ON(PageDirty(dpage));
			nilfs_copy_page(dpage, page, 0);
			unlock_page(dpage);
			put_page(dpage);
		} else {
			struct page *page2;

			/* move the page to the destination cache */
			spin_lock_irq(&smap->tree_lock);
			page2 = radix_tree_delete(&smap->page_tree, offset);
			WARN_ON(page2 != page);

			smap->nrpages--;
			spin_unlock_irq(&smap->tree_lock);

			spin_lock_irq(&dmap->tree_lock);
			err = radix_tree_insert(&dmap->page_tree, offset, page);
			if (unlikely(err < 0)) {
				WARN_ON(err == -EEXIST);
				page->mapping = NULL;
				put_page(page); /* for cache */
			} else {
				page->mapping = dmap;
				dmap->nrpages++;
				if (PageDirty(page))
					radix_tree_tag_set(&dmap->page_tree,
							   offset,
							   PAGECACHE_TAG_DIRTY);
			}
			spin_unlock_irq(&dmap->tree_lock);
		}
		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, 0);

	while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
				  PAGEVEC_SIZE)) {
		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_warning(sb, __func__,
				"discard 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 =
			(1 << BH_Uptodate | 1 << BH_Dirty | 1 << BH_Mapped |
			 1 << BH_Async_Write | 1 << BH_NILFS_Volatile |
			 1 << BH_NILFS_Checked | 1 << BH_NILFS_Redirected);

		bh = head = page_buffers(page);
		do {
			lock_buffer(bh);
			if (!silent) {
				nilfs_warning(sb, __func__,
					"discard block %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 nilfs_page_count_clean_buffers(struct page *page,
					unsigned from, unsigned to)
{
	unsigned block_start, block_end;
	struct buffer_head *bh, *head;
	unsigned 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;
}

void nilfs_mapping_init(struct address_space *mapping, struct inode *inode)
{
	mapping->host = inode;
	mapping->flags = 0;
	mapping_set_gfp_mask(mapping, GFP_NOFS);
	mapping->private_data = NULL;
	mapping->a_ops = &empty_aops;
}

/*
 * NILFS2 needs clear_page_dirty() in the following two cases:
 *
 * 1) For B-tree node pages and data pages of the dat/gcdat, NILFS2 clears
 *    page dirty flags when it copies back pages from the shadow cache
 *    (gcdat->{i_mapping,i_btnode_cache}) to its original cache
 *    (dat->{i_mapping,i_btnode_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) {
		spin_lock_irq(&mapping->tree_lock);
		if (test_bit(PG_dirty, &page->flags)) {
			radix_tree_tag_clear(&mapping->page_tree,
					     page_index(page),
					     PAGECACHE_TAG_DIRTY);
			spin_unlock_irq(&mapping->tree_lock);
			return clear_page_dirty_for_io(page);
		}
		spin_unlock_irq(&mapping->tree_lock);
		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, 0);

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
0bd49f94 RK	1	/*
	2	* page.c - buffer/page management specific to NILFS
	3	*
	4	* Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License as published by
	8	* the Free Software Foundation; either version 2 of the License, or
	9	* (at your option) any later version.
	10	*
	11	* This program is distributed in the hope that it will be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	* GNU General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public License
	17	* along with this program; if not, write to the Free Software
	18	* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	19	*
	20	* Written by Ryusuke Konishi <[email protected]>,
	21	* Seiji Kihara <[email protected]>.
	22	*/
	23
	24	#include <linux/pagemap.h>
	25	#include <linux/writeback.h>
	26	#include <linux/swap.h>
	27	#include <linux/bitops.h>
	28	#include <linux/page-flags.h>
	29	#include <linux/list.h>
	30	#include <linux/highmem.h>
	31	#include <linux/pagevec.h>
5a0e3ad6	32	#include <linux/gfp.h>
0bd49f94 RK	33	#include "nilfs.h"
	34	#include "page.h"
	35	#include "mdt.h"
	36
	37
	38	#define NILFS_BUFFER_INHERENT_BITS \
	39	((1UL << BH_Uptodate) \| (1UL << BH_Mapped) \| (1UL << BH_NILFS_Node) \| \
1cb2d38c	40	(1UL << BH_NILFS_Volatile) \| (1UL << BH_NILFS_Checked))
0bd49f94 RK	41
	42	static struct buffer_head *
	43	__nilfs_get_page_block(struct page *page, unsigned long block, pgoff_t index,
	44	int blkbits, unsigned long b_state)
	45
	46	{
	47	unsigned long first_block;
	48	struct buffer_head *bh;
	49
	50	if (!page_has_buffers(page))
	51	create_empty_buffers(page, 1 << blkbits, b_state);
	52
09cbfeaf	53	first_block = (unsigned long)index << (PAGE_SHIFT - blkbits);
0bd49f94 RK	54	bh = nilfs_page_get_nth_block(page, block - first_block);
	55
	56	touch_buffer(bh);
	57	wait_on_buffer(bh);
	58	return bh;
	59	}
	60
0bd49f94 RK	61	struct buffer_head nilfs_grab_buffer(struct inode inode,
	62	struct address_space *mapping,
	63	unsigned long blkoff,
	64	unsigned long b_state)
	65	{
	66	int blkbits = inode->i_blkbits;
09cbfeaf	67	pgoff_t index = blkoff >> (PAGE_SHIFT - blkbits);
c1c1d709 RK	68	struct page *page;
c1c1d709 RK	69	struct buffer_head *bh;
0bd49f94 RK	70
	71	page = grab_cache_page(mapping, index);
	72	if (unlikely(!page))
	73	return NULL;
	74
	75	bh = __nilfs_get_page_block(page, blkoff, index, blkbits, b_state);
	76	if (unlikely(!bh)) {
	77	unlock_page(page);
09cbfeaf	78	put_page(page);
0bd49f94 RK	79	return NULL;
0bd49f94 RK	80	}
0bd49f94 RK	81	return bh;
	82	}
	83
	84	/**
	85	* nilfs_forget_buffer - discard dirty state
	86	* @inode: owner inode of the buffer
	87	* @bh: buffer head of the buffer to be discarded
	88	*/
	89	void nilfs_forget_buffer(struct buffer_head *bh)
	90	{
	91	struct page *page = bh->b_page;
ead8ecff RK	92	const unsigned long clear_bits =
	93	(1 << BH_Uptodate \| 1 << BH_Dirty \| 1 << BH_Mapped \|
	94	1 << BH_Async_Write \| 1 << BH_NILFS_Volatile \|
	95	1 << BH_NILFS_Checked \| 1 << BH_NILFS_Redirected);
0bd49f94 RK	96
0bd49f94 RK	97	lock_buffer(bh);
ead8ecff	98	set_mask_bits(&bh->b_state, clear_bits, 0);
84338237	99	if (nilfs_page_buffers_clean(page))
0bd49f94 RK	100	__nilfs_clear_page_dirty(page);
0bd49f94 RK	101
0bd49f94 RK	102	bh->b_blocknr = -1;
	103	ClearPageUptodate(page);
	104	ClearPageMappedToDisk(page);
	105	unlock_buffer(bh);
	106	brelse(bh);
	107	}
	108
	109	/**
	110	* nilfs_copy_buffer -- copy buffer data and flags
	111	* @dbh: destination buffer
	112	* @sbh: source buffer
	113	*/
	114	void nilfs_copy_buffer(struct buffer_head dbh, struct buffer_head sbh)
	115	{
	116	void kaddr0, kaddr1;
	117	unsigned long bits;
	118	struct page spage = sbh->b_page, dpage = dbh->b_page;
	119	struct buffer_head *bh;
	120
7b9c0976 CW	121	kaddr0 = kmap_atomic(spage);
7b9c0976 CW	122	kaddr1 = kmap_atomic(dpage);
0bd49f94	123	memcpy(kaddr1 + bh_offset(dbh), kaddr0 + bh_offset(sbh), sbh->b_size);
7b9c0976 CW	124	kunmap_atomic(kaddr1);
7b9c0976 CW	125	kunmap_atomic(kaddr0);
0bd49f94 RK	126
	127	dbh->b_state = sbh->b_state & NILFS_BUFFER_INHERENT_BITS;
	128	dbh->b_blocknr = sbh->b_blocknr;
	129	dbh->b_bdev = sbh->b_bdev;
	130
	131	bh = dbh;
	132	bits = sbh->b_state & ((1UL << BH_Uptodate) \| (1UL << BH_Mapped));
	133	while ((bh = bh->b_this_page) != dbh) {
	134	lock_buffer(bh);
	135	bits &= bh->b_state;
	136	unlock_buffer(bh);
	137	}
	138	if (bits & (1UL << BH_Uptodate))
	139	SetPageUptodate(dpage);
	140	else
	141	ClearPageUptodate(dpage);
	142	if (bits & (1UL << BH_Mapped))
	143	SetPageMappedToDisk(dpage);
	144	else
	145	ClearPageMappedToDisk(dpage);
	146	}
	147
	148	/**
	149	* nilfs_page_buffers_clean - check if a page has dirty buffers or not.
	150	* @page: page to be checked
	151	*
	152	* nilfs_page_buffers_clean() returns zero if the page has dirty buffers.
	153	* Otherwise, it returns non-zero value.
	154	*/
	155	int nilfs_page_buffers_clean(struct page *page)
	156	{
	157	struct buffer_head bh, head;
	158
	159	bh = head = page_buffers(page);
	160	do {
	161	if (buffer_dirty(bh))
	162	return 0;
	163	bh = bh->b_this_page;
	164	} while (bh != head);
	165	return 1;
	166	}
	167
	168	void nilfs_page_bug(struct page *page)
	169	{
	170	struct address_space *m;
aa405b1f	171	unsigned long ino;
0bd49f94 RK	172
	173	if (unlikely(!page)) {
	174	printk(KERN_CRIT "NILFS_PAGE_BUG(NULL)\n");
	175	return;
	176	}
	177
	178	m = page->mapping;
aa405b1f RK	179	ino = m ? m->host->i_ino : 0;
aa405b1f RK	180
0bd49f94 RK	181	printk(KERN_CRIT "NILFS_PAGE_BUG(%p): cnt=%d index#=%llu flags=0x%lx "
0bd49f94 RK	182	"mapping=%p ino=%lu\n",
fe896d18	183	page, page_ref_count(page),
0bd49f94 RK	184	(unsigned long long)page->index, page->flags, m, ino);
	185
	186	if (page_has_buffers(page)) {
	187	struct buffer_head bh, head;
	188	int i = 0;
	189
	190	bh = head = page_buffers(page);
	191	do {
	192	printk(KERN_CRIT
	193	" BH[%d] %p: cnt=%d block#=%llu state=0x%lx\n",
	194	i++, bh, atomic_read(&bh->b_count),
	195	(unsigned long long)bh->b_blocknr, bh->b_state);
	196	bh = bh->b_this_page;
	197	} while (bh != head);
	198	}
	199	}
	200
0bd49f94 RK	201	/**
	202	* nilfs_copy_page -- copy the page with buffers
	203	* @dst: destination page
	204	* @src: source page
	205	* @copy_dirty: flag whether to copy dirty states on the page's buffer heads.
	206	*
7a65004b	207	* This function is for both data pages and btnode pages. The dirty flag
0bd49f94 RK	208	* should be treated by caller. The page must not be under i/o.
	209	* Both src and dst page must be locked
	210	*/
	211	static void nilfs_copy_page(struct page dst, struct page src, int copy_dirty)
	212	{
	213	struct buffer_head dbh, dbufs, sbh, sbufs;
	214	unsigned long mask = NILFS_BUFFER_INHERENT_BITS;
	215
	216	BUG_ON(PageWriteback(dst));
	217
	218	sbh = sbufs = page_buffers(src);
	219	if (!page_has_buffers(dst))
	220	create_empty_buffers(dst, sbh->b_size, 0);
	221
	222	if (copy_dirty)
	223	mask \|= (1UL << BH_Dirty);
	224
	225	dbh = dbufs = page_buffers(dst);
	226	do {
	227	lock_buffer(sbh);
	228	lock_buffer(dbh);
	229	dbh->b_state = sbh->b_state & mask;
	230	dbh->b_blocknr = sbh->b_blocknr;
	231	dbh->b_bdev = sbh->b_bdev;
	232	sbh = sbh->b_this_page;
	233	dbh = dbh->b_this_page;
	234	} while (dbh != dbufs);
	235
	236	copy_highpage(dst, src);
	237
	238	if (PageUptodate(src) && !PageUptodate(dst))
	239	SetPageUptodate(dst);
	240	else if (!PageUptodate(src) && PageUptodate(dst))
	241	ClearPageUptodate(dst);
	242	if (PageMappedToDisk(src) && !PageMappedToDisk(dst))
	243	SetPageMappedToDisk(dst);
	244	else if (!PageMappedToDisk(src) && PageMappedToDisk(dst))
	245	ClearPageMappedToDisk(dst);
	246
	247	do {
	248	unlock_buffer(sbh);
	249	unlock_buffer(dbh);
	250	sbh = sbh->b_this_page;
	251	dbh = dbh->b_this_page;
	252	} while (dbh != dbufs);
	253	}
	254
	255	int nilfs_copy_dirty_pages(struct address_space *dmap,
	256	struct address_space *smap)
	257	{
	258	struct pagevec pvec;
	259	unsigned int i;
	260	pgoff_t index = 0;
	261	int err = 0;
	262
	263	pagevec_init(&pvec, 0);
	264	repeat:
	265	if (!pagevec_lookup_tag(&pvec, smap, &index, PAGECACHE_TAG_DIRTY,
	266	PAGEVEC_SIZE))
	267	return 0;
	268
	269	for (i = 0; i < pagevec_count(&pvec); i++) {
	270	struct page page = pvec.pages[i], dpage;
	271
272	lock_page(page);
273	if (unlikely(!PageDirty(page)))
274	NILFS_PAGE_BUG(page, "inconsistent dirty state");
275
276	dpage = grab_cache_page(dmap, page->index);
277	if (unlikely(!dpage)) {
278	/* No empty page is added to the page cache */
279	err = -ENOMEM;
280	unlock_page(page);
281	break;
282	}
283	if (unlikely(!page_has_buffers(page)))
284	NILFS_PAGE_BUG(page,
285	"found empty page in dat page cache");
286
287	nilfs_copy_page(dpage, page, 1);
288	__set_page_dirty_nobuffers(dpage);
289
290	unlock_page(dpage);
09cbfeaf	291	put_page(dpage);
0bd49f94 RK	292	unlock_page(page);
	293	}
	294	pagevec_release(&pvec);
	295	cond_resched();
	296
	297	if (likely(!err))
	298	goto repeat;
	299	return err;
	300	}
	301
	302	/**
7a65004b	303	* nilfs_copy_back_pages -- copy back pages to original cache from shadow cache
0bd49f94 RK	304	* @dmap: destination page cache
	305	* @smap: source page cache
	306	*
	307	* No pages must no be added to the cache during this process.
	308	* This must be ensured by the caller.
	309	*/
	310	void nilfs_copy_back_pages(struct address_space *dmap,
	311	struct address_space *smap)
	312	{
	313	struct pagevec pvec;
	314	unsigned int i, n;
	315	pgoff_t index = 0;
	316	int err;
	317
	318	pagevec_init(&pvec, 0);
	319	repeat:
	320	n = pagevec_lookup(&pvec, smap, index, PAGEVEC_SIZE);
	321	if (!n)
	322	return;
	323	index = pvec.pages[n - 1]->index + 1;
	324
	325	for (i = 0; i < pagevec_count(&pvec); i++) {
	326	struct page page = pvec.pages[i], dpage;
	327	pgoff_t offset = page->index;
	328
	329	lock_page(page);
	330	dpage = find_lock_page(dmap, offset);
	331	if (dpage) {
	332	/* override existing page on the destination cache */
1f5abe7e	333	WARN_ON(PageDirty(dpage));
0bd49f94 RK	334	nilfs_copy_page(dpage, page, 0);
0bd49f94 RK	335	unlock_page(dpage);
09cbfeaf	336	put_page(dpage);
0bd49f94 RK	337	} else {
	338	struct page *page2;
	339
	340	/* move the page to the destination cache */
	341	spin_lock_irq(&smap->tree_lock);
	342	page2 = radix_tree_delete(&smap->page_tree, offset);
1f5abe7e RK	343	WARN_ON(page2 != page);
1f5abe7e RK	344
0bd49f94 RK	345	smap->nrpages--;
	346	spin_unlock_irq(&smap->tree_lock);
	347
	348	spin_lock_irq(&dmap->tree_lock);
	349	err = radix_tree_insert(&dmap->page_tree, offset, page);
	350	if (unlikely(err < 0)) {
1f5abe7e	351	WARN_ON(err == -EEXIST);
0bd49f94	352	page->mapping = NULL;
09cbfeaf	353	put_page(page); /* for cache */
0bd49f94 RK	354	} else {
	355	page->mapping = dmap;
	356	dmap->nrpages++;
	357	if (PageDirty(page))
	358	radix_tree_tag_set(&dmap->page_tree,
	359	offset,
	360	PAGECACHE_TAG_DIRTY);
	361	}
	362	spin_unlock_irq(&dmap->tree_lock);
	363	}
	364	unlock_page(page);
	365	}
	366	pagevec_release(&pvec);
	367	cond_resched();
	368
	369	goto repeat;
	370	}
	371
8c26c4e2 VD	372	/**
	373	* nilfs_clear_dirty_pages - discard dirty pages in address space
	374	* @mapping: address space with dirty pages for discarding
	375	* @silent: suppress [true] or print [false] warning messages
	376	*/
	377	void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent)
0bd49f94 RK	378	{
	379	struct pagevec pvec;
	380	unsigned int i;
	381	pgoff_t index = 0;
	382
	383	pagevec_init(&pvec, 0);
	384
	385	while (pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
	386	PAGEVEC_SIZE)) {
	387	for (i = 0; i < pagevec_count(&pvec); i++) {
	388	struct page *page = pvec.pages[i];
0bd49f94 RK	389
0bd49f94 RK	390	lock_page(page);
8c26c4e2	391	nilfs_clear_dirty_page(page, silent);
0bd49f94 RK	392	unlock_page(page);
	393	}
	394	pagevec_release(&pvec);
	395	cond_resched();
	396	}
	397	}
	398
8c26c4e2 VD	399	/**
	400	* nilfs_clear_dirty_page - discard dirty page
	401	* @page: dirty page that will be discarded
	402	* @silent: suppress [true] or print [false] warning messages
	403	*/
	404	void nilfs_clear_dirty_page(struct page *page, bool silent)
	405	{
	406	struct inode *inode = page->mapping->host;
	407	struct super_block *sb = inode->i_sb;
	408
dc33f5f3	409	BUG_ON(!PageLocked(page));
8c26c4e2 VD	410
	411	if (!silent) {
	412	nilfs_warning(sb, __func__,
	413	"discard page: offset %lld, ino %lu",
	414	page_offset(page), inode->i_ino);
	415	}
	416
	417	ClearPageUptodate(page);
	418	ClearPageMappedToDisk(page);
	419
	420	if (page_has_buffers(page)) {
	421	struct buffer_head bh, head;
ead8ecff RK	422	const unsigned long clear_bits =
	423	(1 << BH_Uptodate \| 1 << BH_Dirty \| 1 << BH_Mapped \|
	424	1 << BH_Async_Write \| 1 << BH_NILFS_Volatile \|
	425	1 << BH_NILFS_Checked \| 1 << BH_NILFS_Redirected);
8c26c4e2 VD	426
	427	bh = head = page_buffers(page);
	428	do {
	429	lock_buffer(bh);
	430	if (!silent) {
	431	nilfs_warning(sb, __func__,
	432	"discard block %llu, size %zu",
	433	(u64)bh->b_blocknr, bh->b_size);
	434	}
ead8ecff	435	set_mask_bits(&bh->b_state, clear_bits, 0);
8c26c4e2 VD	436	unlock_buffer(bh);
	437	} while (bh = bh->b_this_page, bh != head);
	438	}
	439
	440	__nilfs_clear_page_dirty(page);
	441	}
	442
0bd49f94 RK	443	unsigned nilfs_page_count_clean_buffers(struct page *page,
	444	unsigned from, unsigned to)
	445	{
	446	unsigned block_start, block_end;
	447	struct buffer_head bh, head;
	448	unsigned nc = 0;
	449
	450	for (bh = head = page_buffers(page), block_start = 0;
	451	bh != head \|\| !block_start;
	452	block_start = block_end, bh = bh->b_this_page) {
	453	block_end = block_start + bh->b_size;
	454	if (block_end > from && block_start < to && !buffer_dirty(bh))
	455	nc++;
	456	}
	457	return nc;
	458	}
ae53a0a2	459
b83ae6d4	460	void nilfs_mapping_init(struct address_space mapping, struct inode inode)
ebdfed4d	461	{
aa405b1f	462	mapping->host = inode;
ebdfed4d RK	463	mapping->flags = 0;
ebdfed4d RK	464	mapping_set_gfp_mask(mapping, GFP_NOFS);
252aa6f5	465	mapping->private_data = NULL;
d611b22f	466	mapping->a_ops = &empty_aops;
ebdfed4d	467	}
0bd49f94 RK	468
	469	/*
	470	* NILFS2 needs clear_page_dirty() in the following two cases:
	471	*
	472	* 1) For B-tree node pages and data pages of the dat/gcdat, NILFS2 clears
	473	* page dirty flags when it copies back pages from the shadow cache
	474	* (gcdat->{i_mapping,i_btnode_cache}) to its original cache
	475	* (dat->{i_mapping,i_btnode_cache}).
	476	*
	477	* 2) Some B-tree operations like insertion or deletion may dispose buffers
	478	* in dirty state, and this needs to cancel the dirty state of their pages.
	479	*/
	480	int __nilfs_clear_page_dirty(struct page *page)
	481	{
	482	struct address_space *mapping = page->mapping;
	483
	484	if (mapping) {
	485	spin_lock_irq(&mapping->tree_lock);
	486	if (test_bit(PG_dirty, &page->flags)) {
	487	radix_tree_tag_clear(&mapping->page_tree,
	488	page_index(page),
	489	PAGECACHE_TAG_DIRTY);
	490	spin_unlock_irq(&mapping->tree_lock);
	491	return clear_page_dirty_for_io(page);
	492	}
	493	spin_unlock_irq(&mapping->tree_lock);
	494	return 0;
	495	}
	496	return TestClearPageDirty(page);
	497	}
622daaff RK	498
	499	/**
	500	* nilfs_find_uncommitted_extent - find extent of uncommitted data
	501	* @inode: inode
	502	* @start_blk: start block offset (in)
	503	* @blkoff: start offset of the found extent (out)
	504	*
	505	* This function searches an extent of buffers marked "delayed" which
	506	* starts from a block offset equal to or larger than @start_blk. If
	507	* such an extent was found, this will store the start offset in
	508	* @blkoff and return its length in blocks. Otherwise, zero is
	509	* returned.
	510	*/
	511	unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
	512	sector_t start_blk,
	513	sector_t *blkoff)
	514	{
	515	unsigned int i;
	516	pgoff_t index;
	517	unsigned int nblocks_in_page;
	518	unsigned long length = 0;
	519	sector_t b;
	520	struct pagevec pvec;
	521	struct page *page;
	522
	523	if (inode->i_mapping->nrpages == 0)
	524	return 0;
	525
09cbfeaf KS	526	index = start_blk >> (PAGE_SHIFT - inode->i_blkbits);
09cbfeaf KS	527	nblocks_in_page = 1U << (PAGE_SHIFT - inode->i_blkbits);
622daaff RK	528
	529	pagevec_init(&pvec, 0);
	530
	531	repeat:
	532	pvec.nr = find_get_pages_contig(inode->i_mapping, index, PAGEVEC_SIZE,
	533	pvec.pages);
	534	if (pvec.nr == 0)
	535	return length;
	536
	537	if (length > 0 && pvec.pages[0]->index > index)
	538	goto out;
	539
09cbfeaf	540	b = pvec.pages[0]->index << (PAGE_SHIFT - inode->i_blkbits);
622daaff RK	541	i = 0;
	542	do {
	543	page = pvec.pages[i];
	544
	545	lock_page(page);
	546	if (page_has_buffers(page)) {
	547	struct buffer_head bh, head;
	548
	549	bh = head = page_buffers(page);
	550	do {
	551	if (b < start_blk)
	552	continue;
	553	if (buffer_delay(bh)) {
	554	if (length == 0)
	555	*blkoff = b;
	556	length++;
	557	} else if (length > 0) {
	558	goto out_locked;
	559	}
	560	} while (++b, bh = bh->b_this_page, bh != head);
	561	} else {
	562	if (length > 0)
	563	goto out_locked;
	564
	565	b += nblocks_in_page;
	566	}
	567	unlock_page(page);
	568
	569	} while (++i < pagevec_count(&pvec));
	570
	571	index = page->index + 1;
	572	pagevec_release(&pvec);
	573	cond_resched();
	574	goto repeat;
	575
	576	out_locked:
	577	unlock_page(page);
	578	out:
	579	pagevec_release(&pvec);
	580	return length;
	581	}