nilfs2: B-tree node cache

/*

 * btnode.c - NILFS B-tree node cache

 *

 * 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

 *

 * This file was originally written by Seiji Kihara <kihara@osrg.net>

 * and fully revised by Ryusuke Konishi <ryusuke@osrg.net> for

 * stabilization and simplification.

 *

 */

#include <linux/types.h>

#include <linux/buffer_head.h>

#include <linux/mm.h>

#include <linux/backing-dev.h>

#include "nilfs.h"

#include "mdt.h"

#include "dat.h"

#include "page.h"

#include "btnode.h"

void nilfs_btnode_cache_init_once(struct address_space *btnc)

{

	INIT_RADIX_TREE(&btnc->page_tree, GFP_ATOMIC);

	spin_lock_init(&btnc->tree_lock);

	INIT_LIST_HEAD(&btnc->private_list);

	spin_lock_init(&btnc->private_lock);

	spin_lock_init(&btnc->i_mmap_lock);

	INIT_RAW_PRIO_TREE_ROOT(&btnc->i_mmap);

	INIT_LIST_HEAD(&btnc->i_mmap_nonlinear);

}

static struct address_space_operations def_btnode_aops;

void nilfs_btnode_cache_init(struct address_space *btnc)

{

	btnc->host = NULL;  /* can safely set to host inode ? */

	btnc->flags = 0;

	mapping_set_gfp_mask(btnc, GFP_NOFS);

	btnc->assoc_mapping = NULL;

	btnc->backing_dev_info = &default_backing_dev_info;

	btnc->a_ops = &def_btnode_aops;

}

void nilfs_btnode_cache_clear(struct address_space *btnc)

{

	invalidate_mapping_pages(btnc, 0, -1);

	truncate_inode_pages(btnc, 0);

}

int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,

			      sector_t pblocknr, struct buffer_head **pbh,

			      int newblk)

{

	struct buffer_head *bh;

	struct inode *inode = NILFS_BTNC_I(btnc);

	int err;

	bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);

	if (unlikely(!bh))

		return -ENOMEM;

	err = -EEXIST; /* internal code */

	if (newblk) {

		if (unlikely(buffer_mapped(bh) || buffer_uptodate(bh) ||

			     buffer_dirty(bh))) {

			brelse(bh);

			BUG();

		}

		bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;

		bh->b_blocknr = blocknr;

		set_buffer_mapped(bh);

		set_buffer_uptodate(bh);

		goto found;

	}

	if (buffer_uptodate(bh) || buffer_dirty(bh))

		goto found;

	if (pblocknr == 0) {

		pblocknr = blocknr;

		if (inode->i_ino != NILFS_DAT_INO) {

			struct inode *dat =

				nilfs_dat_inode(NILFS_I_NILFS(inode));

			/* blocknr is a virtual block number */

			err = nilfs_dat_translate(dat, blocknr, &pblocknr);

			if (unlikely(err)) {

				brelse(bh);

				goto out_locked;

			}

		}

	}

	lock_buffer(bh);

	if (buffer_uptodate(bh)) {

		unlock_buffer(bh);

		err = -EEXIST; /* internal code */

		goto found;

	}

	set_buffer_mapped(bh);

	bh->b_bdev = NILFS_I_NILFS(inode)->ns_bdev;

	bh->b_blocknr = pblocknr; /* set block address for read */

	bh->b_end_io = end_buffer_read_sync;

	get_bh(bh);

	submit_bh(READ, bh);

	bh->b_blocknr = blocknr; /* set back to the given block address */

	err = 0;

found:

	*pbh = bh;

out_locked:

	unlock_page(bh->b_page);

	page_cache_release(bh->b_page);

	return err;

}

int nilfs_btnode_get(struct address_space *btnc, __u64 blocknr,

		     sector_t pblocknr, struct buffer_head **pbh, int newblk)

{

	struct buffer_head *bh;

	int err;

	err = nilfs_btnode_submit_block(btnc, blocknr, pblocknr, pbh, newblk);

	if (err == -EEXIST) /* internal code (cache hit) */

		return 0;

	if (unlikely(err))

		return err;

	bh = *pbh;

	wait_on_buffer(bh);

	if (!buffer_uptodate(bh)) {

		brelse(bh);

		return -EIO;

	}

	return 0;

}

/**

 * nilfs_btnode_delete - delete B-tree node buffer

 * @bh: buffer to be deleted

 *

 * nilfs_btnode_delete() invalidates the specified buffer and delete the page

 * including the buffer if the page gets unbusy.

 */

void nilfs_btnode_delete(struct buffer_head *bh)

{

	struct address_space *mapping;

	struct page *page = bh->b_page;

	pgoff_t index = page_index(page);

	int still_dirty;

	page_cache_get(page);

	lock_page(page);

	wait_on_page_writeback(page);

	nilfs_forget_buffer(bh);

	still_dirty = PageDirty(page);

	mapping = page->mapping;

	unlock_page(page);

	page_cache_release(page);

	if (!still_dirty && mapping)

		invalidate_inode_pages2_range(mapping, index, index);

}

/**

 * nilfs_btnode_prepare_change_key

 *  prepare to move contents of the block for old key to one of new key.

 *  the old buffer will not be removed, but might be reused for new buffer.

 *  it might return -ENOMEM because of memory allocation errors,

 *  and might return -EIO because of disk read errors.

 */

int nilfs_btnode_prepare_change_key(struct address_space *btnc,

				    struct nilfs_btnode_chkey_ctxt *ctxt)

{

	struct buffer_head *obh, *nbh;

	struct inode *inode = NILFS_BTNC_I(btnc);

	__u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;

	int err;

	if (oldkey == newkey)

		return 0;

	obh = ctxt->bh;

	ctxt->newbh = NULL;

	if (inode->i_blkbits == PAGE_CACHE_SHIFT) {

		lock_page(obh->b_page);

		/*

		 * We cannot call radix_tree_preload for the kernels older

		 * than 2.6.23, because it is not exported for modules.

		 */

		err = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);

		if (err)

			goto failed_unlock;

		/* BUG_ON(oldkey != obh->b_page->index); */

		if (unlikely(oldkey != obh->b_page->index))

			NILFS_PAGE_BUG(obh->b_page,

				       "invalid oldkey %lld (newkey=%lld)",

				       (unsigned long long)oldkey,

				       (unsigned long long)newkey);

retry:

		spin_lock_irq(&btnc->tree_lock);

		err = radix_tree_insert(&btnc->page_tree, newkey, obh->b_page);

		spin_unlock_irq(&btnc->tree_lock);

		/*

		 * Note: page->index will not change to newkey until

		 * nilfs_btnode_commit_change_key() will be called.

		 * To protect the page in intermediate state, the page lock

		 * is held.

		 */

		radix_tree_preload_end();

		if (!err)

			return 0;

		else if (err != -EEXIST)

			goto failed_unlock;

		err = invalidate_inode_pages2_range(btnc, newkey, newkey);

		if (!err)

			goto retry;

		/* fallback to copy mode */

		unlock_page(obh->b_page);

	}

	err = nilfs_btnode_get(btnc, newkey, 0, &nbh, 1);

	if (likely(!err)) {

		BUG_ON(nbh == obh);

		ctxt->newbh = nbh;

	}

	return err;

 failed_unlock:

	unlock_page(obh->b_page);

	return err;

}

/**

 * nilfs_btnode_commit_change_key

 *  commit the change_key operation prepared by prepare_change_key().

 */

void nilfs_btnode_commit_change_key(struct address_space *btnc,

				    struct nilfs_btnode_chkey_ctxt *ctxt)

{

	struct buffer_head *obh = ctxt->bh, *nbh = ctxt->newbh;

	__u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;

	struct page *opage;

	if (oldkey == newkey)

		return;

	if (nbh == NULL) {	/* blocksize == pagesize */

		opage = obh->b_page;

		if (unlikely(oldkey != opage->index))

			NILFS_PAGE_BUG(opage,

				       "invalid oldkey %lld (newkey=%lld)",

				       (unsigned long long)oldkey,

				       (unsigned long long)newkey);

		if (!test_set_buffer_dirty(obh) && TestSetPageDirty(opage))

			BUG();

		spin_lock_irq(&btnc->tree_lock);

		radix_tree_delete(&btnc->page_tree, oldkey);

		radix_tree_tag_set(&btnc->page_tree, newkey,

				   PAGECACHE_TAG_DIRTY);

		spin_unlock_irq(&btnc->tree_lock);

		opage->index = obh->b_blocknr = newkey;

		unlock_page(opage);

	} else {

		nilfs_copy_buffer(nbh, obh);

		nilfs_btnode_mark_dirty(nbh);

		nbh->b_blocknr = newkey;

		ctxt->bh = nbh;

		nilfs_btnode_delete(obh); /* will decrement bh->b_count */

	}

}

/**

 * nilfs_btnode_abort_change_key

 *  abort the change_key operation prepared by prepare_change_key().

 */

void nilfs_btnode_abort_change_key(struct address_space *btnc,

				   struct nilfs_btnode_chkey_ctxt *ctxt)

{

	struct buffer_head *nbh = ctxt->newbh;

	__u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;

	if (oldkey == newkey)

		return;

	if (nbh == NULL) {	/* blocksize == pagesize */

		spin_lock_irq(&btnc->tree_lock);

		radix_tree_delete(&btnc->page_tree, newkey);

		spin_unlock_irq(&btnc->tree_lock);

		unlock_page(ctxt->bh->b_page);

	} else

		brelse(nbh);

}

/*

 * btnode.h - NILFS B-tree node cache

 *

 * 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 Seiji Kihara <kihara@osrg.net>

 * Revised by Ryusuke Konishi <ryusuke@osrg.net>

 */

#ifndef _NILFS_BTNODE_H

#define _NILFS_BTNODE_H

#include <linux/types.h>

#include <linux/buffer_head.h>

#include <linux/fs.h>

#include <linux/backing-dev.h>

struct nilfs_btnode_chkey_ctxt {

	__u64 oldkey;

	__u64 newkey;

	struct buffer_head *bh;

	struct buffer_head *newbh;

};

void nilfs_btnode_cache_init_once(struct address_space *);

void nilfs_btnode_cache_init(struct address_space *);

void nilfs_btnode_cache_clear(struct address_space *);

int nilfs_btnode_submit_block(struct address_space *, __u64, sector_t,

			      struct buffer_head **, int);

int nilfs_btnode_get(struct address_space *, __u64, sector_t,

		     struct buffer_head **, int);

void nilfs_btnode_delete(struct buffer_head *);

int nilfs_btnode_prepare_change_key(struct address_space *,

				    struct nilfs_btnode_chkey_ctxt *);

void nilfs_btnode_commit_change_key(struct address_space *,

				    struct nilfs_btnode_chkey_ctxt *);

void nilfs_btnode_abort_change_key(struct address_space *,

				   struct nilfs_btnode_chkey_ctxt *);

#define nilfs_btnode_mark_dirty(bh)	nilfs_mark_buffer_dirty(bh)

#endif	/* _NILFS_BTNODE_H */