path: root/fs/ext4/move_extent.c

/*
 * Copyright (c) 2008,2009 NEC Software Tohoku, Ltd.
 * Written by Takashi Sato <t-sato@yk.jp.nec.com>
 *            Akira Fujita <a-fujita@rs.jp.nec.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2.1 of the GNU Lesser General Public License
 * as published by the Free Software Foundation.
 *
 * 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.
 */

#include <linux/fs.h>
#include <linux/quotaops.h>
#include <linux/slab.h>
#include "ext4_jbd2.h"
#include "ext4.h"
#include "ext4_extents.h"

/**
 * get_ext_path - Find an extent path for designated logical block number.
 *
 * @inode:	an inode which is searched
 * @lblock:	logical block number to find an extent path
 * @path:	pointer to an extent path pointer (for output)
 *
 * ext4_ext_find_extent wrapper. Return 0 on success, or a negative error value
 * on failure.
 */
static inline int
get_ext_path(struct inode *inode, ext4_lblk_t lblock,
		struct ext4_ext_path **orig_path)
{
	int ret = 0;
	struct ext4_ext_path *path;

	path = ext4_ext_find_extent(inode, lblock, *orig_path);
	if (IS_ERR(path))
		ret = PTR_ERR(path);
	else if (path[ext_depth(inode)].p_ext == NULL)
		ret = -ENODATA;
	else
		*orig_path = path;

	return ret;
}

/**
 * copy_extent_status - Copy the extent's initialization status
 *
 * @src:	an extent for getting initialize status
 * @dest:	an extent to be set the status
 */
static void
copy_extent_status(struct ext4_extent *src, struct ext4_extent *dest)
{
	if (ext4_ext_is_uninitialized(src))
		ext4_ext_mark_uninitialized(dest);
	else
		dest->ee_len = cpu_to_le16(ext4_ext_get_actual_len(dest));
}

/**
 * mext_next_extent - Search for the next extent and set it to "extent"
 *
 * @inode:	inode which is searched
 * @path:	this will obtain data for the next extent
 * @extent:	pointer to the next extent we have just gotten
 *
 * Search the next extent in the array of ext4_ext_path structure (@path)
 * and set it to ext4_extent structure (@extent). In addition, the member of
 * @path (->p_ext) also points the next extent. Return 0 on success, 1 if
 * ext4_ext_path structure refers to the last extent, or a negative error
 * value on failure.
 */
static int
mext_next_extent(struct inode *inode, struct ext4_ext_path *path,
		      struct ext4_extent **extent)
{
	struct ext4_extent_header *eh;
	int ppos, leaf_ppos = path->p_depth;

	ppos = leaf_ppos;
	if (EXT_LAST_EXTENT(path[ppos].p_hdr) > path[ppos].p_ext) {
		/* leaf block */
		*extent = ++path[ppos].p_ext;
		path[ppos].p_block = ext4_ext_pblock(path[ppos].p_ext);
		return 0;
	}

	while (--ppos >= 0) {
		if (EXT_LAST_INDEX(path[ppos].p_hdr) >
		    path[ppos].p_idx) {
			int cur_ppos = ppos;

			/* index block */
			path[ppos].p_idx++;
			path[ppos].p_block = ext4_idx_pblock(path[ppos].p_idx);
			if (path[ppos+1].p_bh)
				brelse(path[ppos+1].p_bh);
			path[ppos+1].p_bh =
				sb_bread(inode->i_sb, path[ppos].p_block);
			if (!path[ppos+1].p_bh)
				return -EIO;
			path[ppos+1].p_hdr =
				ext_block_hdr(path[ppos+1].p_bh);

			/* Halfway index block */
			while (++cur_ppos < leaf_ppos) {
				path[cur_ppos].p_idx =
					EXT_FIRST_INDEX(path[cur_ppos].p_hdr);
				path[cur_ppos].p_block =
					ext4_idx_pblock(path[cur_ppos].p_idx);
				if (path[cur_ppos+1].p_bh)
					brelse(path[cur_ppos+1].p_bh);
				path[cur_ppos+1].p_bh = sb_bread(inode->i_sb,
					path[cur_ppos].p_block);
				if (!path[cur_ppos+1].p_bh)
					return -EIO;
				path[cur_ppos+1].p_hdr =
					ext_block_hdr(path[cur_ppos+1].p_bh);
			}

			path[leaf_ppos].p_ext = *extent = NULL;

			eh = path[leaf_ppos].p_hdr;
			if (le16_to_cpu(eh->eh_entries) == 0)
				/* empty leaf is found */
				return -ENODATA;

			/* leaf block */
			path[leaf_ppos].p_ext = *extent =
				EXT_FIRST_EXTENT(path[leaf_ppos].p_hdr);
			path[leaf_ppos].p_block =
					ext4_ext_pblock(path[leaf_ppos].p_ext);
			return 0;
		}
	}
	/* We found the last extent */
	return 1;
}

/**
 * ext4_double_down_write_data_sem - Acquire two inodes' write lock
 *                                   of i_data_sem
 *
 * Acquire write lock of i_data_sem of the two inodes
 */
void
ext4_double_down_write_data_sem(struct inode *first, struct inode *second)
{
	if (first < second) {
		down_write(&EXT4_I(first)->i_data_sem);
		down_write_nested(&EXT4_I(second)->i_data_sem, SINGLE_DEPTH_NESTING);
	} else {
		down_write(&EXT4_I(second)->i_data_sem);
		down_write_nested(&EXT4_I(first)->i_data_sem, SINGLE_DEPTH_NESTING);

	}
}

/**
 * ext4_double_up_write_data_sem - Release two inodes' write lock of i_data_sem
 *
 * @orig_inode:		original inode structure to be released its lock first
 * @donor_inode:	donor inode structure to be released its lock second
 * Release write lock of i_data_sem of two inodes (orig and donor).
 */
void
ext4_double_up_write_data_sem(struct inode *orig_inode,
			      struct inode *donor_inode)
{
	up_write(&EXT4_I(orig_inode)->i_data_sem);
	up_write(&EXT4_I(donor_inode)->i_data_sem);
}

/**
 * mext_insert_across_blocks - Insert extents across leaf block
 *
 * @handle:		journal handle
 * @orig_inode:		original inode
 * @o_start:		first original extent to be changed
 * @o_end:		last original extent to be changed
 * @start_ext:		first new extent to be inserted
 * @new_ext:		middle of new extent to be inserted
 * @end_ext:		last new extent to be inserted
 *
 * Allocate a new leaf block and insert extents into it. Return 0 on success,
 * or a negative error value on failure.
 */
static int
mext_insert_across_blocks(handle_t *handle, struct inode *orig_inode,
		struct ext4_extent *o_start, struct ext4_extent *o_end,
		struct ext4_extent *start_ext, struct ext4_extent *new_ext,
		struct ext4_extent *end_ext)
{
	struct ext4_ext_path *orig_path = NULL;
	ext4_lblk_t eblock = 0;
	int new_flag = 0;
	int end_flag = 0;
	int err = 0;

	if (start_ext->ee_len && new_ext->ee_len && end_ext->ee_len) {
		if (o_start == o_end) {

			/*       start_ext   new_ext    end_ext
			 * donor |---------|-----------|--------|
			 * orig  |------------------------------|
			 */
			end_flag = 1;
		} else {

			/*       start_ext   new_ext   end_ext
			 * donor |---------|----------|---------|
			 * orig  |---------------|--------------|
			 */
			o_end->ee_block = end_ext->ee_block;
			o_end->ee_len = end_ext->ee_len;
			ext4_ext_store_pblock(o_end, ext4_ext_pblock(end_ext));
		}

		o_start->ee_len = start_ext->ee_len;
		eblock = le32_to_cpu(start_ext->ee_block);
		new_flag = 1;

	} else if (start_ext->ee_len && new_ext->ee_len &&
		   !end_ext->ee_len && o_start == o_end) {

		/*	 start_ext	new_ext
		 * donor |--------------|---------------|
		 * orig  |------------------------------|
		 */
		o_start->ee_len = start_ext->ee_len;
		eblock = le32_to_cpu(start_ext->ee_blo