path: root/fs/nilfs2/inode.c

/*
 * inode.c - NILFS inode operations.
 *
 * 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 <ryusuke@osrg.net>
 *
 */

#include <linux/buffer_head.h>
#include <linux/gfp.h>
#include <linux/mpage.h>
#include <linux/writeback.h>
#include <linux/uio.h>
#include "nilfs.h"
#include "btnode.h"
#include "segment.h"
#include "page.h"
#include "mdt.h"
#include "cpfile.h"
#include "ifile.h"

struct nilfs_iget_args {
	u64 ino;
	__u64 cno;
	struct nilfs_root *root;
	int for_gc;
};

void nilfs_inode_add_blocks(struct inode *inode, int n)
{
	struct nilfs_root *root = NILFS_I(inode)->i_root;

	inode_add_bytes(inode, (1 << inode->i_blkbits) * n);
	if (root)
		atomic_add(n, &root->blocks_count);
}

void nilfs_inode_sub_blocks(struct inode *inode, int n)
{
	struct nilfs_root *root = NILFS_I(inode)->i_root;

	inode_sub_bytes(inode, (1 << inode->i_blkbits) * n);
	if (root)
		atomic_sub(n, &root->blocks_count);
}

/**
 * nilfs_get_block() - get a file block on the filesystem (callback function)
 * @inode - inode struct of the target file
 * @blkoff - file block number
 * @bh_result - buffer head to be mapped on
 * @create - indicate whether allocating the block or not when it has not
 *      been allocated yet.
 *
 * This function does not issue actual read request of the specified data
 * block. It is done by VFS.
 */
int nilfs_get_block(struct inode *inode, sector_t blkoff,
		    struct buffer_head *bh_result, int create)
{
	struct nilfs_inode_info *ii = NILFS_I(inode);
	__u64 blknum = 0;
	int err = 0, ret;
	struct inode *dat = NILFS_I_NILFS(inode)->ns_dat;
	unsigned maxblocks = bh_result->b_size >> inode->i_blkbits;

	down_read(&NILFS_MDT(dat)->mi_sem);
	ret = nilfs_bmap_lookup_contig(ii->i_bmap, blkoff, &blknum, maxblocks);
	up_read(&NILFS_MDT(dat)->mi_sem);
	if (ret >= 0) {	/* found */
		map_bh(bh_result, inode->i_sb, blknum);
		if (ret > 0)
			bh_result->b_size = (ret << inode->i_blkbits);
		goto out;
	}
	/* data block was not found */
	if (ret == -ENOENT && create) {
		struct nilfs_transaction_info ti;

		bh_result->b_blocknr = 0;
		err = nilfs_transaction_begin(inode->i_sb, &ti, 1);
		if (unlikely(err))
			goto out;
		err = nilfs_bmap_insert(ii->i_bmap, (unsigned long)blkoff,
					(unsigned long)bh_result);
		if (unlikely(err != 0)) {
			if (err == -EEXIST) {
				/*
				 * The get_block() function could be called
				 * from multiple callers for an inode.
				 * However, the page having this block must
				 * be locked in this case.
				 */
				printk(KERN_WARNING
				       "nilfs_get_block: a race condition "
				       "while inserting a data block. "
				       "(inode number=%lu, file block "
				       "offset=%llu)\n",
				       inode->i_ino,
				       (unsigned long long)blkoff);
				err = 0;
			}
			nilfs_transaction_abort(inode->i_sb);
			goto out;
		}
		nilfs_mark_inode_dirty(inode);
		nilfs_transaction_commit(inode->i_sb); /* never fails */
		/* Error handling should be detailed */
		set_buffer_new(bh_result);
		set_buffer_delay(bh_result);
		map_bh(bh_result, inode->i_sb, 0); /* dbn must be changed
						      to proper value */
	} else if (ret == -ENOENT) {
		/* not found is not error (e.g. hole); must return without
		   the mapped state flag. */
		;
	} else {
		err = ret;
	}

 out:
	return err;
}

/**
 * nilfs_readpage() - implement readpage() method of nilfs_aops {}
 * address_space_operations.
 * @file - file struct of the file to be read
 *