src/ext4/ext4_extents.c

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 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.
 *
 * You should have received a copy of the GNU General Public Licens
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-
 */

#include "ext2fs.h"
#include <linux/ext4.h>

#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable: 4018)
#pragma warning(disable: 4242)
#pragma warning(disable: 4244)
#endif


/*
 * used by extent splitting.
 */
#define EXT4_EXT_MAY_ZEROOUT	0x1  /* safe to zeroout if split fails \
					due to ENOSPC */
#define EXT4_EXT_MARK_UNWRIT1	0x2  /* mark first half unwritten */
#define EXT4_EXT_MARK_UNWRIT2	0x4  /* mark second half unwritten */

#define EXT4_EXT_DATA_VALID1	0x8  /* first half contains valid data */
#define EXT4_EXT_DATA_VALID2	0x10 /* second half contains valid data */

#define CONFIG_EXTENT_TEST
#ifdef CONFIG_EXTENT_TEST

#define ext4_mark_inode_dirty(icb, handle, n) ext3_mark_inode_dirty(icb, n)
static inline ext4_fsblk_t ext4_inode_to_goal_block(struct inode *inode)
{
	PEXT2_VCB Vcb;
	Vcb = inode->i_sb->s_priv;
	return (inode->i_ino - 1) / BLOCKS_PER_GROUP;
}

static ext4_fsblk_t ext4_new_meta_blocks(void *icb, handle_t *handle, struct inode *inode,
		ext4_fsblk_t goal,
		unsigned int flags,
		unsigned long *count, int *errp)
{
	NTSTATUS status;
	ULONG blockcnt = (count)?*count:1;
	ULONG block = 0;

	status = Ext2NewBlock((PEXT2_IRP_CONTEXT)icb,
			inode->i_sb->s_priv,
			0, goal,
			&block,
			&blockcnt);
	if (count)
		*count = blockcnt;

	if (!NT_SUCCESS(status)) {
		*errp = Ext2LinuxError(status);
		return 0;
	}
	inode->i_blocks += (blockcnt * (inode->i_sb->s_blocksize >> 9));
	return block;
}

static void ext4_free_blocks(void *icb, handle_t *handle, struct inode *inode, void *fake,
		ext4_fsblk_t block, int count, int flags)
{
	Ext2FreeBlock((PEXT2_IRP_CONTEXT)icb, inode->i_sb->s_priv, block, count);
	inode->i_blocks -= count * (inode->i_sb->s_blocksize >> 9);
	return;
}

static inline void ext_debug(char *str, ...)
{
}
#if TRUE
#define EXT4_ERROR_INODE(inode, str, ...) do {                      \
            DbgPrint("inode[%p]: " str "\n", inode, ##__VA_ARGS__); \
        } while(0)
#else
#define EXT4_ERROR_INODE
#endif

#define ext4_std_error(s, err)
#define assert ASSERT

#endif

/*
 * Return the right sibling of a tree node(either leaf or indexes node)
 */

#define EXT_MAX_BLOCKS 0xffffffff


static inline int ext4_ext_space_block(struct inode *inode, int check)
{
	int size;

	size = (inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
		/ sizeof(struct ext4_extent);
#ifdef AGGRESSIVE_TEST
	if (!check && size > 6)
		size = 6;
#endif
	return size;
}

static inline int ext4_ext_space_block_idx(struct inode *inode, int check)
{
	int size;

	size = (inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
		/ sizeof(struct ext4_extent_idx);
#ifdef AGGRESSIVE_TEST
	if (!check && size > 5)
		size = 5;
#endif
	return size;
}

static inline int ext4_ext_space_root(struct inode *inode, int check)
{
	int size;

	size = sizeof(EXT4_I(inode)->i_block);
	size -= sizeof(struct ext4_extent_header);
	size /= sizeof(struct ext4_extent);
#ifdef AGGRESSIVE_TEST
	if (!check && size > 3)
		size = 3;
#endif
	return size;
}

static inline int ext4_ext_space_root_idx(struct inode *inode, int check)
{
	int size;

	size = sizeof(EXT4_I(inode)->i_block);
	size -= sizeof(struct ext4_extent_header);
	size /= sizeof(struct ext4_extent_idx);
#ifdef AGGRESSIVE_TEST
	if (!check && size > 4)
		size = 4;
#endif
	return size;
}

static int
ext4_ext_max_entries(struct inode *inode, int depth)
{
	int max;

	if (depth == ext_depth(inode)) {
		if (depth == 0)
			max = ext4_ext_space_root(inode, 1);
		else
			max = ext4_ext_space_root_idx(inode, 1);
	} else {
		if (depth == 0)
			max = ext4_ext_space_block(inode, 1);
		else
			max = ext4_ext_space_block_idx(inode, 1);
	}

	return max;
}

static int __ext4_ext_check(const char *function, unsigned int line,
		struct inode *inode,
		struct ext4_extent_header *eh, int depth,
		ext4_fsblk_t pblk);

/*
 * read_extent_tree_block:
 * Get a buffer_head by extents_bread, and read fresh data from the storage.
 */
static struct buffer_head *
__read_extent_tree_block(const char *function, unsigned int line,
		struct inode *inode, ext4_fsblk_t pblk, int depth,
		int flags)
{
	struct buffer_head		*bh;
	int				err;

	bh = extents_bread(inode->i_sb, pblk);
	if (!bh)
		return ERR_PTR(-ENOMEM);

	if (!buffer_uptodate(bh)) {
		err = -EIO;
		goto errout;
	}
	if (buffer_verified(bh))
		return bh;
	err = __ext4_ext_check(function, line, inode,
			ext_block_hdr(bh), depth, pblk);
	if (err)
		goto errout;
	set_buffer_verified(bh);
	return bh;
errout:
	extents_brelse(bh);
	return ERR_PTR(err);

}

#define read_extent_tree_block(inode, pblk, depth, flags)		\
	__read_extent_tree_block("", __LINE__, (inode), (pblk),   \
			(depth), (flags))

#define ext4_ext_check(inode, eh, depth, pblk)			\
	__ext4_ext_check("", __LINE__, (inode), (eh), (depth), (pblk))

int ext4_ext_check_inode(struct inode *inode)
{
	return ext4_ext_check(inode, ext_inode_hdr(inode), ext_depth(inode), 0);
}

static uint32_t ext4_ext_block_csum(struct inode *inode,
		struct ext4_extent_header *eh)
{
	/*return ext4_crc32c(inode->i_csum, eh, EXT4_EXTENT_TAIL_OFFSET(eh));*/
	return 0;
}

static void ext4_extent_block_csum_set(struct inode *inode,
		struct ext4_extent_header *eh)
{
	struct ext4_extent_tail *tail;

	tail = find_ext4_extent_tail(eh);
	tail->et_checksum = ext4_ext_block_csum(
			inode, eh);
}

static int ext4_split_extent_at(void *icb,
			     handle_t *handle,
			     struct inode *inode,
			     struct ext4_ext_path **ppath,
			     ext4_lblk_t split,
			     int split_flag,
			     int flags);

static inline int
ext4_force_split_extent_at(void *icb, handle_t *handle, struct inode *inode,
		struct ext4_ext_path **ppath, ext4_lblk_t lblk,
		int nofail)
{
	struct ext4_ext_path *path = *ppath;
	int unwritten = ext4_ext_is_unwritten(path[path->p_depth].p_ext);

	return ext4_split_extent_at(icb, handle, inode, ppath, lblk, unwritten ?
			EXT4_EXT_MARK_UNWRIT1|EXT4_EXT_MARK_UNWRIT2 : 0,
			EXT4_EX_NOCACHE | EXT4_GET_BLOCKS_PRE_IO |
			(nofail ? EXT4_GET_BLOCKS_METADATA_NOFAIL:0));
}

/*
 * could return:
 *  - EROFS
 *  - ENOMEM
 */

static int ext4_ext_get_access(void *icb, handle_t *handle, struct inode *inode,
		struct ext4_ext_path *path)
{
	if (path->p_bh) {
		/* path points to block */

		return ext4_journal_get_write_access(icb, handle, path->p_bh);

	}
	/* path points to leaf/index in inode body */
	/* we use in-core data, no need to protect them */
	return 0;
}


static ext4_fsblk_t ext4_ext_find_goal(struct inode *inode,
		struct ext4_ext_path *path,
		ext4_lblk_t block)
{
	if (path) {
		int depth = path->p_depth;
		struct ext4_extent *ex;

		/*
		 * Try to predict block placement assuming that we are
		 * filling in a file which will eventually be
		 * non-sparse --- i.e., in the case of libbfd writing
		 * an ELF object sections out-of-order but in a way
		 * the eventually results in a contiguous object or
		 * executable file, or some database extending a table
		 * space file.  However, this is actually somewhat
		 * non-ideal if we are writing a sparse file such as
		 * qemu or KVM writing a raw image file that is going
		 * to stay fairly sparse, since it will end up
		 * fragmenting the file system's free space.  Maybe we
		 * should have some hueristics or some way to allow
		 * userspace to pass a hint to file system,
		 * especially if the latter case turns out to be
		 * common.
		 */
		ex = path[depth].p_ext;
		if (ex) {
			ext4_fsblk_t ext_pblk = ext4_ext_pblock(ex);
			ext4_lblk_t ext_block = le32_to_cpu(ex->ee_block);

			if (block > ext_block)
				return ext_pblk + (block - ext_block);
			else
				return ext_pblk - (ext_block - block);
		}

		/* it looks like index is empty;
		 * try to find starting block from index itself */
		if (path[depth].p_bh)
			return path[depth].p_bh->b_blocknr;
	}

	/* OK. use inode's group */
	return ext4_inode_to_goal_block(inode);
}

/*
 * Allocation for a meta data block
 */
static ext4_fsblk_t
ext4_ext_new_meta_block(void *icb, handle_t *handle, struct inode *inode,
		struct ext4_ext_path *path,
		struct ext4_extent *ex, int *err, unsigned int flags)
{
	ext4_fsblk_t goal, newblock;

	goal = ext4_ext_find_goal(inode, path, le32_to_cpu(ex->ee_block));
	newblock = ext4_new_meta_blocks(icb, handle, inode, goal, flags,
			NULL, err);
	return newblock;
}

int __ext4_ext_dirty(const char *where, unsigned int line,
		void *icb, handle_t *handle,
		struct inode *inode,
		struct ext4_ext_path *path)
{
	int err;

	if (path->p_bh) {
		ext4_extent_block_csum_set(inode, ext_block_hdr(path->p_bh));
		/* path points to block */
		err = __ext4_handle_dirty_metadata(where, line, icb, handle, inode, path->p_bh);
	} else {
		/* path points to leaf/index in inode body */
		err = ext4_mark_inode_dirty(icb, handle, inode);
	}
	return err;
}

void ext4_ext_drop_refs(struct ext4_ext_path *path)
{
	int depth, i;

	if (!path)
		return;
	depth = path->p_depth;
	for (i = 0; i <= depth; i++, path++)
		if (path->p_bh) {
			extents_brelse(path->p_bh);
			path->p_bh = NULL;
		}
}

/*
 * Check that whether the basic information inside the extent header
 * is correct or not.
 */
static int __ext4_ext_check(const char *function, unsigned int line,
		struct inode *inode,
		struct ext4_extent_header *eh, int depth,
		ext4_fsblk_t pblk)
{
	struct ext4_extent_tail *tail;
	const char *error_msg;
#ifndef __REACTOS__
	int max = 0;
#endif
	if (eh->eh_magic != EXT4_EXT_MAGIC) {
		error_msg = "invalid magic";
		goto corrupted;
	}
	if (le16_to_cpu(eh->eh_depth) != depth) {
		error_msg = "unexpected eh_depth";
		goto corrupted;
	}
	if (eh->eh_max == 0) {
		error_msg = "invalid eh_max";
		goto corrupted;
	}
	if (eh->eh_entries > eh->eh_max) {
		error_msg = "invalid eh_entries";
		goto corrupted;
	}

	tail = find_ext4_extent_tail(eh);
	if (tail->et_checksum != ext4_ext_block_csum(inode, eh)) {
		ext_debug("Warning: extent checksum damaged? tail->et_checksum = "
				"%lu, ext4_ext_block_csum = %lu\n",
				tail->et_checksum, ext4_ext_block_csum(inode, eh));
	}

	return 0;

corrupted:
	ext_debug("corrupted! %s\n", error_msg);
	return -EIO;
}

/*
 * ext4_ext_binsearch_idx:
 * binary search for the closest index of the given block
 * the header must be checked before calling this
 */
static void
ext4_ext_binsearch_idx(struct inode *inode,
		struct ext4_ext_path *path, ext4_lblk_t block)
{
	struct ext4_extent_header *eh = path->p_hdr;
	struct ext4_extent_idx *r, *l, *m;

	ext_debug("binsearch for %u(idx):  ", block);

	l = EXT_FIRST_INDEX(eh) + 1;
	r = EXT_LAST_INDEX(eh);
	while (l <= r) {
		m = l + (r - l) / 2;
		if (block < (m->ei_block))
			r = m - 1;
		else
			l = m + 1;
		ext_debug("%p(%u):%p(%u):%p(%u) ", l, (l->ei_block),
				m, (m->ei_block),
				r, (r->ei_block));
	}

	path->p_idx = l - 1;
	ext_debug("  -> %u->%lld ", (path->p_idx->ei_block),
			ext4_idx_pblock(path->p_idx));

#ifdef CHECK_BINSEARCH
	{
		struct ext4_extent_idx *chix, *ix;
		int k;

		chix = ix = EXT_FIRST_INDEX(eh);
		for (k = 0; k < (eh->eh_entries); k++, ix++) {
			if (k != 0 &&
					(ix->ei_block) <= (ix[-1].ei_block)) {
				printk(KERN_DEBUG "k=%d, ix=0x%p, "
						"first=0x%p\n", k,
						ix, EXT_FIRST_INDEX(eh));
				printk(KERN_DEBUG "%u <= %u\n",
						(ix->ei_block),
						(ix[-1].ei_block));
			}
			BUG_ON(k && (ix->ei_block)
					<= (ix[-1].ei_block));
			if (block < (ix->ei_block))
				break;
			chix = ix;
		}
		BUG_ON(chix != path->p_idx);
	}
#endif

}

/*
 * ext4_ext_binsearch:
 * binary search for closest extent of the given block
 * the header must be checked before calling this
 */
static void
ext4_ext_binsearch(struct inode *inode,
		struct ext4_ext_path *path, ext4_lblk_t block)
{
	struct ext4_extent_header *eh = path->p_hdr;
	struct ext4_extent *r, *l, *m;

	if (eh->eh_entries == 0) {
		/*
		 * this leaf is empty:
		 * we get such a leaf in split/add case
		 */
		return;
	}

	ext_debug("binsearch for %u:  ", block);

	l = EXT_FIRST_EXTENT(eh) + 1;
	r = EXT_LAST_EXTENT(eh);

	while (l <= r) {
		m = l + (r - l) / 2;
		if (block < m->ee_block)
			r = m - 1;
		else
			l = m + 1;
		ext_debug("%p(%u):%p(%u):%p(%u) ", l, l->ee_block,
				m, (m->ee_block),
				r, (r->ee_block));
	}

	path->p_ext = l - 1;
	ext_debug("  -> %d:%llu:[%d]%d ",
			(path->p_ext->ee_block),
			ext4_ext_pblock(path->p_ext),
			ext4_ext_is_unwritten(path->p_ext),
			ext4_ext_get_actual_len(path->p_ext));

#ifdef CHECK_BINSEARCH
	{
		struct ext4_extent *chex, *ex;
		int k;

		chex = ex = EXT_FIRST_EXTENT(eh);
		for (k = 0; k < le16_to_cpu(eh->eh_entries); k++, ex++) {
			BUG_ON(k && (ex->ee_block)
					<= (ex[-1].ee_block));
			if (block < (ex->ee_block))
				break;
			chex = ex;
		}
		BUG_ON(chex != path->p_ext);
	}
#endif

}

#ifdef EXT_DEBUG
static void ext4_ext_show_path(struct inode *inode, struct ext4_ext_path *path)
{
	int k, l = path->p_depth;

	ext_debug("path:");
	for (k = 0; k <= l; k++, path++) {
		if (path->p_idx) {
			ext_debug("  %d->%llu", le32_to_cpu(path->p_idx->ei_block),
					ext4_idx_pblock(path->p_idx));
		} else if (path->p_ext) {
			ext_debug("  %d:[%d]%d:%llu ",
					le32_to_cpu(path->p_ext->ee_block),
					ext4_ext_is_unwritten(path->p_ext),
					ext4_ext_get_actual_len(path->p_ext),
					ext4_ext_pblock(path->p_ext));
		} else
			ext_debug("  []");
	}
	ext_debug("\n");
}

static void ext4_ext_show_leaf(struct inode *inode, struct ext4_ext_path *path)
{
	int depth = ext_depth(inode);
	struct ext4_extent_header *eh;
	struct ext4_extent *ex;
	int i;

	if (!path)
		return;

	eh = path[depth].p_hdr;
	ex = EXT_FIRST_EXTENT(eh);

	ext_debug("Displaying leaf extents for inode %lu\n", inode->i_ino);

	for (i = 0; i < le16_to_cpu(eh->eh_entries); i++, ex++) {
		ext_debug("%d:[%d]%d:%llu ", le32_to_cpu(ex->ee_block),
				ext4_ext_is_unwritten(ex),
				ext4_ext_get_actual_len(ex), ext4_ext_pblock(ex));
	}
	ext_debug("\n");
}

static void ext4_ext_show_move(struct inode *inode, struct ext4_ext_path *path,
		ext4_fsblk_t newblock, int level)
{
	int depth = ext_depth(inode);
	struct ext4_extent *ex;

	if (depth != level) {
		struct ext4_extent_idx *idx;
		idx = path[level].p_idx;
		while (idx <= EXT_MAX_INDEX(path[level].p_hdr)) {
			ext_debug("%d: move %d:%llu in new index %llu\n", level,
					le32_to_cpu(idx->ei_block),
					ext4_idx_pblock(idx),
					newblock);
			idx++;
		}

		return;
	}

	ex = path[depth].p_ext;
	while (ex <= EXT_MAX_EXTENT(path[depth].p_hdr)) {
		ext_debug("move %d:%llu:[%d]%d in new leaf %llu\n",
				le32_to_cpu(ex->ee_block),
				ext4_ext_pblock(ex),
				ext4_ext_is_unwritten(ex),
				ext4_ext_get_actual_len(ex),
				newblock);
		ex++;
	}
}

#else
#define ext4_ext_show_path(inode, path)
#define ext4_ext_show_leaf(inode, path)
#define ext4_ext_show_move(inode, path, newblock, level)
#endif

struct ext4_ext_path *
ext4_find_extent(struct inode *inode, ext4_lblk_t block,
		struct ext4_ext_path **orig_path, int flags)
{
	struct ext4_extent_header *eh;
	struct buffer_head *bh;
	struct ext4_ext_path *path = orig_path ? *orig_path : NULL;
	short int depth, i, ppos = 0;
	int ret;

	eh = ext_inode_hdr(inode);
	depth = ext_depth(inode);

	if (path) {
		ext4_ext_drop_refs(path);
		if (depth > path[0].p_maxdepth) {
			kfree(path);
			*orig_path = path = NULL;
		}
	}
	if (!path) {
		/* account possible depth increase */
		path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 2),
				GFP_NOFS);
		if (unlikely(!path))
			return ERR_PTR(-ENOMEM);
		path[0].p_maxdepth = depth + 1;
	}
	path[0].p_hdr = eh;
	path[0].p_bh = NULL;

	i = depth;
	/* walk through the tree */
	while (i) {
		ext_debug("depth %d: num %d, max %d\n",
				ppos, le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));

		ext4_ext_binsearch_idx(inode, path + ppos, block);
		path[ppos].p_block = ext4_idx_pblock(path[ppos].p_idx);
		path[ppos].p_depth = i;
		path[ppos].p_ext = NULL;

		bh = read_extent_tree_block(inode, path[ppos].p_block, --i,
				flags);
		if (unlikely(IS_ERR(bh))) {
			ret = PTR_ERR(bh);
			goto err;
		}

		eh = ext_block_hdr(bh);
		ppos++;
		if (unlikely(ppos > depth)) {
			extents_brelse(bh);
			EXT4_ERROR_INODE(inode,
					"ppos %d > depth %d", ppos, depth);
			ret = -EIO;
			goto err;
		}
		path[ppos].p_bh = bh;
		path[ppos].p_hdr = eh;
	}

	path[ppos].p_depth = i;
	path[ppos].p_ext = NULL;
	path[ppos].p_idx = NULL;

	/* find extent */
	ext4_ext_binsearch(inode, path + ppos, block);
	/* if not an empty leaf */
	if (path[ppos].p_ext)
		path[ppos].p_block = ext4_ext_pblock(path[ppos].p_ext);

	ext4_ext_show_path(inode, path);

	return path;

err:
	ext4_ext_drop_refs(path);
	if (path) {
		kfree(path);
		if (orig_path)
			*orig_path = NULL;
	}
	return ERR_PTR(ret);
}

/*
 * ext4_ext_insert_index:
 * insert new index [@logical;@ptr] into the block at @curp;
 * check where to insert: before @curp or after @curp
 */
static int ext4_ext_insert_index(void *icb, handle_t *handle, struct inode *inode,
		struct ext4_ext_path *curp,
		int logical, ext4_fsblk_t ptr)
{
	struct ext4_extent_idx *ix;
	int len, err;

	err = ext4_ext_get_access(icb, handle, inode, curp);
	if (err)
		return err;

	if (unlikely(logical == le32_to_cpu(curp->p_idx->ei_block))) {
		EXT4_ERROR_INODE(inode,
				"logical %d == ei_block %d!",
				logical, le32_to_cpu(curp->p_idx->ei_block));
		return -EIO;
	}

	if (unlikely(le16_to_cpu(curp->p_hdr->eh_entries)
				>= le16_to_cpu(curp->p_hdr->eh_max))) {
		EXT4_ERROR_INODE(inode,
				"eh_entries %d >= eh_max %d!",
				le16_to_cpu(curp->p_hdr->eh_entries),
				le16_to_cpu(curp->p_hdr->eh_max));
		return -EIO;
	}

	if (logical > le32_to_cpu(curp->p_idx->ei_block)) {
		/* insert after */
		ext_debug("insert new index %d after: %llu\n", logical, ptr);
		ix = curp->p_idx + 1;
	} else {
		/* insert before */
		ext_debug("insert new index %d before: %llu\n", logical, ptr);
		ix = curp->p_idx;
	}

	len = EXT_LAST_INDEX(curp->p_hdr) - ix + 1;
	BUG_ON(len < 0);
	if (len > 0) {
		ext_debug("insert new index %d: "
				"move %d indices from 0x%p to 0x%p\n",
				logical, len, ix, ix + 1);
		memmove(ix + 1, ix, len * sizeof(struct ext4_extent_idx));
	}

	if (unlikely(ix > EXT_MAX_INDEX(curp->p_hdr))) {
		EXT4_ERROR_INODE(inode, "ix > EXT_MAX_INDEX!");
		return -EIO;
	}

	ix->ei_block = cpu_to_le32(logical);
	ext4_idx_store_pblock(ix, ptr);
	le16_add_cpu(&curp->p_hdr->eh_entries, 1);

	if (unlikely(ix > EXT_LAST_INDEX(curp->p_hdr))) {
		EXT4_ERROR_INODE(inode, "ix > EXT_LAST_INDEX!");
		return -EIO;
	}

	err = ext4_ext_dirty(icb, handle, inode, curp);
	ext4_std_error(inode->i_sb, err);

	return err;
}

/*
 * ext4_ext_split:
 * inserts new subtree into the path, using free index entry
 * at depth @at:
 * - allocates all needed blocks (new leaf and all intermediate index blocks)
 * - makes decision where to split
 * - moves remaining extents and index entries (right to the split point)
 *   into the newly allocated blocks
 * - initializes subtree
 */
static int ext4_ext_split(void *icb, handle_t *handle, struct inode *inode,
		unsigned int flags,
		struct ext4_ext_path *path,
		struct ext4_extent *newext, int at)
{
	struct buffer_head *bh = NULL;
	int depth = ext_depth(inode);
	struct ext4_extent_header *neh;
	struct ext4_extent_idx *fidx;
	int i = at, k, m, a;
	ext4_fsblk_t newblock, oldblock;
	__le32 border;
	ext4_fsblk_t *ablocks = NULL; /* array of allocated blocks */
	int err = 0;

	/* make decision: where to split? */
	/* FIXME: now decision is simplest: at current extent */

	/* if current leaf will be split, then we should use
	 * border from split point */
	if (unlikely(path[depth].p_ext > EXT_MAX_EXTENT(path[depth].p_hdr))) {
		EXT4_ERROR_INODE(inode, "p_ext > EXT_MAX_EXTENT!");
		return -EIO;
	}
	if (path[depth].p_ext != EXT_MAX_EXTENT(path[depth].p_hdr)) {
		border = path[depth].p_ext[1].ee_block;
		ext_debug("leaf will be split."
				" next leaf starts at %d\n",
				le32_to_cpu(border));
	} else {
		border = newext->ee_block;
		ext_debug("leaf will be added."
				" next leaf starts at %d\n",
				le32_to_cpu(border));
	}

	/*
	 * If error occurs, then we break processing
	 * and mark filesystem read-only. index won't
	 * be inserted and tree will be in consistent
	 * state. Next mount will repair buffers too.
	 */

	/*
	 * Get array to track all allocated blocks.
	 * We need this to handle errors and free blocks
	 * upon them.
	 */
	ablocks = kzalloc(sizeof(ext4_fsblk_t) * depth, GFP_NOFS);
	if (!ablocks)
		return -ENOMEM;

	/* allocate all needed blocks */
	ext_debug("allocate %d blocks for indexes/leaf\n", depth - at);
	for (a = 0; a < depth - at; a++) {
		newblock = ext4_ext_new_meta_block(icb, handle, inode, path,
				newext, &err, flags);
		if (newblock == 0)
			goto cleanup;
		ablocks[a] = newblock;
	}

	/* initialize new leaf */
	newblock = ablocks[--a];
	if (unlikely(newblock == 0)) {
		EXT4_ERROR_INODE(inode, "newblock == 0!");
		err = -EIO;
		goto cleanup;
	}
	bh = extents_bwrite(inode->i_sb, newblock);
	if (unlikely(!bh)) {
		err = -ENOMEM;
		goto cleanup;
	}

	err = ext4_journal_get_create_access(icb, handle, bh);
	if (err)
		goto cleanup;

	neh = ext_block_hdr(bh);
	neh->eh_entries = 0;
	neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode, 0));
	neh->eh_magic = cpu_to_le16(EXT4_EXT_MAGIC);
	neh->eh_depth = 0;

	/* move remainder of path[depth] to the new leaf */
	if (unlikely(path[depth].p_hdr->eh_entries !=
				path[depth].p_hdr->eh_max)) {
		EXT4_ERROR_INODE(inode, "eh_entries %d != eh_max %d!",
				path[depth].p_hdr->eh_entries,
				path[depth].p_hdr->eh_max);
		err = -EIO;
		goto cleanup;
	}
	/* start copy from next extent */
	m = EXT_MAX_EXTENT(path[depth].p_hdr) - path[depth].p_ext++;
	ext4_ext_show_move(inode, path, newblock, depth);
	if (m) {
		struct ext4_extent *ex;
		ex = EXT_FIRST_EXTENT(neh);
		memmove(ex, path[depth].p_ext, sizeof(struct ext4_extent) * m);
		le16_add_cpu(&neh->eh_entries, m);
	}

	ext4_extent_block_csum_set(inode, neh);
	set_buffer_uptodate(bh);

	err = ext4_handle_dirty_metadata(icb, handle, inode, bh);
	if (err)
		goto cleanup;
	extents_brelse(bh);
	bh = NULL;

	/* correct old leaf */
	if (m) {
		err = ext4_ext_get_access(icb, handle, inode, path + depth);
		if (err)
			goto cleanup;
		le16_add_cpu(&path[depth].p_hdr->eh_entries, -m);
		err = ext4_ext_dirty(icb, handle, inode, path + depth);
		if (err)
			goto cleanup;

	}

	/* create intermediate indexes */
	k = depth - at - 1;
	if (unlikely(k < 0)) {
		EXT4_ERROR_INODE(inode, "k %d < 0!", k);
		err = -EIO;
		goto cleanup;
	}
	if (k)
		ext_debug("create %d intermediate indices\n", k);
	/* insert new index into current index block */
	/* current depth stored in i var */
	i = depth - 1;
	while (k--) {
		oldblock = newblock;
		newblock = ablocks[--a];
		bh = extents_bwrite(inode->i_sb, newblock);
		if (unlikely(!bh)) {
			err = -ENOMEM;
			goto cleanup;
		}

		err = ext4_journal_get_create_access(icb, handle, bh);
		if (err)
			goto cleanup;

		neh = ext_block_hdr(bh);
		neh->eh_entries = cpu_to_le16(1);
		neh->eh_magic = cpu_to_le16(EXT4_EXT_MAGIC);
		neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode, 0));
		neh->eh_depth = cpu_to_le16(depth - i);
		fidx = EXT_FIRST_INDEX(neh);
		fidx->ei_block = border;
		ext4_idx_store_pblock(fidx, oldblock);

		ext_debug("int.index at %d (block %llu): %u -> %llu\n",
				i, newblock, le32_to_cpu(border), oldblock);

		/* move remainder of path[i] to the new index block */
		if (unlikely(EXT_MAX_INDEX(path[i].p_hdr) !=
					EXT_LAST_INDEX(path[i].p_hdr))) {
			EXT4_ERROR_INODE(inode,
					"EXT_MAX_INDEX != EXT_LAST_INDEX ee_block %d!",
					le32_to_cpu(path[i].p_ext->ee_block));
			err = -EIO;
			goto cleanup;
		}
		/* start copy indexes */
		m = EXT_MAX_INDEX(path[i].p_hdr) - path[i].p_idx++;
		ext_debug("cur 0x%p, last 0x%p\n", path[i].p_idx,
				EXT_MAX_INDEX(path[i].p_hdr));
		ext4_ext_show_move(inode, path, newblock, i);
		if (m) {
			memmove(++fidx, path[i].p_idx,
					sizeof(struct ext4_extent_idx) * m);
			le16_add_cpu(&neh->eh_entries, m);
		}
		ext4_extent_block_csum_set(inode, neh);
		set_buffer_uptodate(bh);

		err = ext4_handle_dirty_metadata(icb, handle, inode, bh);
		if (err)
			goto cleanup;
		extents_brelse(bh);
		bh = NULL;

		/* correct old index */
		if (m) {
			err = ext4_ext_get_access(icb, handle, inode, path + i);
			if (err)
				goto cleanup;
			le16_add_cpu(&path[i].p_hdr->eh_entries, -m);
			err = ext4_ext_dirty(icb, handle, inode, path + i);
			if (err)
				goto cleanup;
		}

		i--;
	}

	/* insert new index */
	err = ext4_ext_insert_index(icb, handle, inode, path + at,
			le32_to_cpu(border), newblock);

cleanup:
	if (bh)
		extents_brelse(bh);

	if (err) {
		/* free all allocated blocks in error case */
		for (i = 0; i < depth; i++) {
			if (!ablocks[i])
				continue;
			ext4_free_blocks(icb, handle, inode, NULL, ablocks[i], 1,
					EXT4_FREE_BLOCKS_METADATA);
		}
	}
	kfree(ablocks);

	return err;
}

/*
 * ext4_ext_grow_indepth:
 * implements tree growing procedure:
 * - allocates new block
 * - moves top-level data (index block or leaf) into the new block
 * - initializes new top-level, creating index that points to the
 *   just created block
 */
static int ext4_ext_grow_indepth(void *icb, handle_t *handle, struct inode *inode,
		unsigned int flags)
{
	struct ext4_extent_header *neh;
	struct buffer_head *bh;
	ext4_fsblk_t newblock, goal = 0;
	int err = 0;

	/* Try to prepend new index to old one */
	if (ext_depth(inode))
		goal = ext4_idx_pblock(EXT_FIRST_INDEX(ext_inode_hdr(inode)));
	goal = ext4_inode_to_goal_block(inode);
	newblock = ext4_new_meta_blocks(icb, handle, inode, goal, flags,
			NULL, &err);
	if (newblock == 0)
		return err;

	bh = extents_bwrite(inode->i_sb, newblock);
	if (!bh)
		return -ENOMEM;

	err = ext4_journal_get_create_access(icb, handle, bh);
	if (err)
		goto out;

	/* move top-level index/leaf into new block */
	memmove(bh->b_data, EXT4_I(inode)->i_block,
			sizeof(EXT4_I(inode)->i_block));

	/* set size of new block */
	neh = ext_block_hdr(bh);
	/* old root could have indexes or leaves
	 * so calculate e_max right way */
	if (ext_depth(inode))
		neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode, 0));
	else
		neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode, 0));
	neh->eh_magic = cpu_to_le16(EXT4_EXT_MAGIC);
	ext4_extent_block_csum_set(inode, neh);
	set_buffer_uptodate(bh);

	err = ext4_handle_dirty_metadata(icb, handle, inode, bh);
	if (err)
		goto out;

	/* Update top-level index: num,max,pointer */
	neh = ext_inode_hdr(inode);
	neh->eh_entries = cpu_to_le16(1);
	ext4_idx_store_pblock(EXT_FIRST_INDEX(neh), newblock);
	if (neh->eh_depth == 0) {
		/* Root extent block becomes index block */
		neh->eh_max = cpu_to_le16(ext4_ext_space_root_idx(inode, 0));
		EXT_FIRST_INDEX(neh)->ei_block =
			EXT_FIRST_EXTENT(neh)->ee_block;
	}
	ext_debug("new root: num %d(%d), lblock %d, ptr %llu\n",
			(neh->eh_entries), (neh->eh_max),
			(EXT_FIRST_INDEX(neh)->ei_block),
			ext4_idx_pblock(EXT_FIRST_INDEX(neh)));

	le16_add_cpu(&neh->eh_depth, 1);
	ext4_mark_inode_dirty(icb, handle, inode);
out:
	extents_brelse(bh);

	return err;
}

/*
 * ext4_ext_create_new_leaf:
 * finds empty index and adds new leaf.
 * if no free index is found, then it requests in-depth growing.
 */
static int ext4_ext_create_new_leaf(void *icb, handle_t *handle, struct inode *inode,
		unsigned int mb_flags,
		unsigned int gb_flags,
		struct ext4_ext_path **ppath,
		struct ext4_extent *newext)
{
	struct ext4_ext_path *path = *ppath;
	struct ext4_ext_path *curp;
	int depth, i, err = 0;

repeat:
	i = depth = ext_depth(inode);

	/* walk up to the tree and look for free index entry */
	curp = path + depth;
	while (i > 0 && !EXT_HAS_FREE_INDEX(curp)) {
		i--;
		curp--;
	}

	/* we use already allocated block for index block,
	 * so subsequent data blocks should be contiguous */
	if (EXT_HAS_FREE_INDEX(curp)) {
		/* if we found index with free entry, then use that
		 * entry: create all needed subtree and add new leaf */
		err = ext4_ext_split(icb, handle, inode, mb_flags, path, newext, i);
		if (err)
			goto out;

		/* refill path */
		path = ext4_find_extent(inode,
				(ext4_lblk_t)le32_to_cpu(newext->ee_block),
				ppath, gb_flags);
		if (IS_ERR(path))
			err = PTR_ERR(path);
	} else {
		/* tree is full, time to grow in depth */
		err = ext4_ext_grow_indepth(icb, handle, inode, mb_flags);
		if (err)
			goto out;

		/* refill path */
		path = ext4_find_extent(inode,
				(ext4_lblk_t)le32_to_cpu(newext->ee_block),
				ppath, gb_flags);
		if (IS_ERR(path)) {
			err = PTR_ERR(path);
			goto out;
		}

		/*
		 * only first (depth 0 -> 1) produces free space;
		 * in all other cases we have to split the grown tree
		 */
		depth = ext_depth(inode);
		if (path[depth].p_hdr->eh_entries == path[depth].p_hdr->eh_max) {
			/* now we need to split */
			goto repeat;
		}
	}

out:
	return err;
}

/*
 * search the closest allocated block to the left for *logical
 * and returns it at @logical + it's physical address at @phys
 * if *logical is the smallest allocated block, the function
 * returns 0 at @phys
 * return value contains 0 (success) or error code
 */
static int ext4_ext_search_left(struct inode *inode,
		struct ext4_ext_path *path,
		ext4_lblk_t *logical, ext4_fsblk_t *phys)
{
	struct ext4_extent_idx *ix;
	struct ext4_extent *ex;
	int depth, ee_len;

	if (unlikely(path == NULL)) {
		EXT4_ERROR_INODE(inode, "path == NULL *logical %d!", *logical);
		return -EIO;
	}
	depth = path->p_depth;
	*phys = 0;

	if (depth == 0 && path->p_ext == NULL)
		return 0;

	/* usually extent in the path covers blocks smaller
	 * then *logical, but it can be that extent is the
	 * first one in the file */

	ex = path[depth].p_ext;
	ee_len = ext4_ext_get_actual_len(ex);
	if (*logical < le32_to_cpu(ex->ee_block)) {
		if (unlikely(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex)) {
			EXT4_ERROR_INODE(inode,
					"EXT_FIRST_EXTENT != ex *logical %d ee_block %d!",
					*logical, le32_to_cpu(ex->ee_block));
			return -EIO;
		}
		while (--depth >= 0) {
			ix = path[depth].p_idx;
			if (unlikely(ix != EXT_FIRST_INDEX(path[depth].p_hdr))) {
				EXT4_ERROR_INODE(inode,
						"ix (%d) != EXT_FIRST_INDEX (%d) (depth %d)!",
						ix != NULL ? le32_to_cpu(ix->ei_block) : 0,
						EXT_FIRST_INDEX(path[depth].p_hdr) != NULL ?
						le32_to_cpu(EXT_FIRST_INDEX(path[depth].p_hdr)->ei_block) : 0,
						depth);
				return -EIO;
			}
		}
		return 0;
	}

	if (unlikely(*logical < (le32_to_cpu(ex->ee_block) + ee_len))) {
		EXT4_ERROR_INODE(inode,
				"logical %d < ee_block %d + ee_len %d!",
				*logical, le32_to_cpu(ex->ee_block), ee_len);
		return -EIO;
	}

	*logical = le32_to_cpu(ex->ee_block) + ee_len - 1;
	*phys = ext4_ext_pblock(ex) + ee_len - 1;
	return 0;
}

/*
 * search the closest allocated block to the right for *logical
 * and returns it at @logical + it's physical address at @phys
 * if *logical is the largest allocated block, the function
 * returns 0 at @phys
 * return value contains 0 (success) or error code
 */
static int ext4_ext_search_right(struct inode *inode,
		struct ext4_ext_path *path,
		ext4_lblk_t *logical, ext4_fsblk_t *phys,
		struct ext4_extent **ret_ex)
{
	struct buffer_head *bh = NULL;
	struct ext4_extent_header *eh;
	struct ext4_extent_idx *ix;
	struct ext4_extent *ex;
	ext4_fsblk_t block;
	int depth;	/* Note, NOT eh_depth; depth from top of tree */
	int ee_len;

	if ((path == NULL)) {
		EXT4_ERROR_INODE(inode, "path == NULL *logical %d!", *logical);
		return -EIO;
	}
	depth = path->p_depth;
	*phys = 0;

	if (depth == 0 && path->p_ext == NULL)
		return 0;

	/* usually extent in the path covers blocks smaller
	 * then *logical, but it can be that extent is the
	 * first one in the file */

	ex = path[depth].p_ext;
	ee_len = ext4_ext_get_actual_len(ex);
	/*if (*logical < le32_to_cpu(ex->ee_block)) {*/
	if (*logical < (ex->ee_block)) {
		if (unlikely(EXT_FIRST_EXTENT(path[depth].p_hdr) != ex)) {
			EXT4_ERROR_INODE(inode,
					"first_extent(path[%d].p_hdr) != ex",
					depth);
			return -EIO;
		}
		while (--depth >= 0) {
			ix = path[depth].p_idx;
			if (unlikely(ix != EXT_FIRST_INDEX(path[depth].p_hdr))) {
				EXT4_ERROR_INODE(inode,
						"ix != EXT_FIRST_INDEX *logical %d!",
						*logical);
				return -EIO;
			}
		}
		goto found_extent;
	}

	/*if (unlikely(*logical < (le32_to_cpu(ex->ee_block) + ee_len))) {*/
	if (unlikely(*logical < ((ex->ee_block) + ee_len))) {
		EXT4_ERROR_INODE(inode,
				"logical %d < ee_block %d + ee_len %d!",
				/**logical, le32_to_cpu(ex->ee_block), ee_len);*/
			*logical, (ex->ee_block), ee_len);
		return -EIO;
	}

	if (ex != EXT_LAST_EXTENT(path[depth].p_hdr)) {
		/* next allocated block in this leaf */
		ex++;
		goto found_extent;
	}

	/* go up and search for index to the right */
	while (--depth >= 0) {
		ix = path[depth].p_idx;
		if (ix != EXT_LAST_INDEX(path[depth].p_hdr))
			goto got_index;
	}

	/* we've gone up to the root and found no index to the right */
	return 0;

got_index:
	/* we've found index to the right, let's
	 * follow it and find the closest allocated
	 * block to the right */
	ix++;
	block = ext4_idx_pblock(ix);
	while (++depth < path->p_depth) {
		/* subtract from p_depth to get proper eh_depth */
		bh = read_extent_tree_block(inode, block,
				path->p_depth - depth, 0);
		if (IS_ERR(bh))
			return PTR_ERR(bh);
		eh = ext_block_hdr(bh);
		ix = EXT_FIRST_INDEX(eh);
		block = ext4_idx_pblock(ix);
		extents_brelse(bh);
	}

	bh = read_extent_tree_block(inode, block, path->p_depth - depth, 0);
	if (IS_ERR(bh))
		return PTR_ERR(bh);
	eh = ext_block_hdr(bh);
	ex = EXT_FIRST_EXTENT(eh);
found_extent:
	/**logical = le32_to_cpu(ex->ee_block);*/
	*logical = (ex->ee_block);
	*phys = ext4_ext_pblock(ex);
	*ret_ex = ex;
	if (bh)
		extents_brelse(bh);
	return 0;
}

/*
 * ext4_ext_next_allocated_block:
 * returns allocated block in subsequent extent or EXT_MAX_BLOCKS.
 * NOTE: it considers block number from index entry as
 * allocated block. Thus, index entries have to be consistent
 * with leaves.
 */
ext4_lblk_t
ext4_ext_next_allocated_block(struct ext4_ext_path *path)
{
	int depth;

	depth = path->p_depth;

	if (depth == 0 && path->p_ext == NULL)
		return EXT_MAX_BLOCKS;

	while (depth >= 0) {
		if (depth == path->p_depth) {
			/* leaf */
			if (path[depth].p_ext &&
					path[depth].p_ext !=
					EXT_LAST_EXTENT(path[depth].p_hdr))
				return le32_to_cpu(path[depth].p_ext[1].ee_block);
		} else {
			/* index */
			if (path[depth].p_idx !=
					EXT_LAST_INDEX(path[depth].p_hdr))
				return le32_to_cpu(path[depth].p_idx[1].ei_block);
		}
		depth--;
	}

	return EXT_MAX_BLOCKS;
}

/*
 * ext4_ext_next_leaf_block:
 * returns first allocated block from next leaf or EXT_MAX_BLOCKS
 */
static ext4_lblk_t ext4_ext_next_leaf_block(struct ext4_ext_path *path)
{
	int depth;

	BUG_ON(path == NULL);
	depth = path->p_depth;

	/* zero-tree has no leaf blocks at all */
	if (depth == 0)
		return EXT_MAX_BLOCKS;

	/* go to index block */
	depth--;

	while (depth >= 0) {
		if (path[depth].p_idx !=
				EXT_LAST_INDEX(path[depth].p_hdr))
			return (ext4_lblk_t)
				le32_to_cpu(path[depth].p_idx[1].ei_block);
		depth--;
	}

	return EXT_MAX_BLOCKS;
}

/*
 * ext4_ext_correct_indexes:
 * if leaf gets modified and modified extent is first in the leaf,
 * then we have to correct all indexes above.
 * TODO: do we need to correct tree in all cases?
 */
static int ext4_ext_correct_indexes(void *icb, handle_t *handle, struct inode *inode,
		struct ext4_ext_path *path)
{
	struct ext4_extent_header *eh;
	int depth = ext_depth(inode);
	struct ext4_extent *ex;
	__le32 border;
	int k, err = 0;

	eh = path[depth].p_hdr;
	ex = path[depth].p_ext;

	if (unlikely(ex == NULL || eh == NULL)) {
		EXT4_ERROR_INODE(inode,
				"ex %p == NULL or eh %p == NULL", ex, eh);
		return -EIO;
	}

	if (depth == 0) {
		/* there is no tree at all */
		return 0;
	}

	if (ex != EXT_FIRST_EXTENT(eh)) {
		/* we correct tree if first leaf got modified only */
		return 0;
	}

	/*
	 * TODO: we need correction if border is smaller than current one
	 */
	k = depth - 1;
	border = path[depth].p_ext->ee_block;
	err = ext4_ext_get_access(icb, handle, inode, path + k);
	if (err)
		return err;
	path[k].p_idx->ei_block = border;
	err = ext4_ext_dirty(icb, handle, inode, path + k);
	if (err)
		return err;

	while (k--) {
		/* change all left-side indexes */
		if (path[k+1].p_idx != EXT_FIRST_INDEX(path[k+1].p_hdr))
			break;
		err = ext4_ext_get_access(icb, handle, inode, path + k);
		if (err)
			break;
		path[k].p_idx->ei_block = border;
		err = ext4_ext_dirty(icb, handle, inode, path + k);
		if (err)
			break;
	}

	return err;
}

int
ext4_can_extents_be_merged(struct inode *inode, struct ext4_extent *ex1,
		struct ext4_extent *ex2)
{
	unsigned short ext1_ee_len, ext2_ee_len;

	/*
	 * Make sure that both extents are initialized. We don't merge
	 * unwritten extents so that we can be sure that end_io code has
	 * the extent that was written properly split out and conversion to
	 * initialized is trivial.
	 */
	if (ext4_ext_is_unwritten(ex1) != ext4_ext_is_unwritten(ex2))
		return 0;

	ext1_ee_len = ext4_ext_get_actual_len(ex1);
	ext2_ee_len = ext4_ext_get_actual_len(ex2);

	if (le32_to_cpu(ex1->ee_block) + ext1_ee_len !=
			le32_to_cpu(ex2->ee_block))
		return 0;

	/*
	 * To allow future support for preallocated extents to be added
	 * as an RO_COMPAT feature, refuse to merge to extents if
	 * this can result in the top bit of ee_len being set.
	 */
	if (ext1_ee_len + ext2_ee_len > EXT_INIT_MAX_LEN)
		return 0;
	if (ext4_ext_is_unwritten(ex1) &&
			(ext1_ee_len + ext2_ee_len > EXT_UNWRITTEN_MAX_LEN))
		return 0;
#ifdef AGGRESSIVE_TEST
	if (ext1_ee_len >= 4)
		return 0;
#endif

	if (ext4_ext_pblock(ex1) + ext1_ee_len == ext4_ext_pblock(ex2))
		return 1;
	return 0;
}

/*
 * This function tries to merge the "ex" extent to the next extent in the tree.
 * It always tries to merge towards right. If you want to merge towards
 * left, pass "ex - 1" as argument instead of "ex".
 * Returns 0 if the extents (ex and ex+1) were _not_ merged and returns
 * 1 if they got merged.
 */
static int ext4_ext_try_to_merge_right(struct inode *inode,
		struct ext4_ext_path *path,
		struct ext4_extent *ex)
{
	struct ext4_extent_header *eh;
	unsigned int depth, len;
	int merge_done = 0, unwritten;

	depth = ext_depth(inode);
	assert(path[depth].p_hdr != NULL);
	eh = path[depth].p_hdr;

	while (ex < EXT_LAST_EXTENT(eh)) {
		if (!ext4_can_extents_be_merged(inode, ex, ex + 1))
			break;
		/* merge with next extent! */
		unwritten = ext4_ext_is_unwritten(ex);
		ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
				+ ext4_ext_get_actual_len(ex + 1));
		if (unwritten)
			ext4_ext_mark_unwritten(ex);

		if (ex + 1 < EXT_LAST_EXTENT(eh)) {
			len = (EXT_LAST_EXTENT(eh) - ex - 1)
				* sizeof(struct ext4_extent);
			memmove(ex + 1, ex + 2, len);
		}
		le16_add_cpu(&eh->eh_entries, -1);
		merge_done = 1;
		if (!eh->eh_entries)
			EXT4_ERROR_INODE(inode, "eh->eh_entries = 0!");
	}

	return merge_done;
}

/*
 * This function does a very simple check to see if we can collapse
 * an extent tree with a single extent tree leaf block into the inode.
 */
static void ext4_ext_try_to_merge_up(void *icb, handle_t *handle,
		struct inode *inode,
		struct ext4_ext_path *path)
{
	size_t s;
	unsigned max_root = ext4_ext_space_root(inode, 0);
	ext4_fsblk_t blk;

	if ((path[0].p_depth != 1) ||
			(le16_to_cpu(path[0].p_hdr->eh_entries) != 1) ||
			(le16_to_cpu(path[1].p_hdr->eh_entries) > max_root))
		return;

	/*
	 * We need to modify the block allocation bitmap and the block
	 * group descriptor to release the extent tree block.  If we
	 * can't get the journal credits, give up.
	 */
	if (ext4_journal_extend(icb, handle, 2))
		return;

	/*
	 * Copy the extent data up to the inode
	 */
	blk = ext4_idx_pblock(path[0].p_idx);
	s = le16_to_cpu(path[1].p_hdr->eh_entries) *
		sizeof(struct ext4_extent_idx);
	s += sizeof(struct ext4_extent_header);

	path[1].p_maxdepth = path[0].p_maxdepth;
	memcpy(path[0].p_hdr, path[1].p_hdr, s);
	path[0].p_depth = 0;
	path[0].p_ext = EXT_FIRST_EXTENT(path[0].p_hdr) +
		(path[1].p_ext - EXT_FIRST_EXTENT(path[1].p_hdr));
	path[0].p_hdr->eh_max = cpu_to_le16(max_root);

	extents_brelse(path[1].p_bh);
	ext4_free_blocks(icb, handle, inode, NULL, blk, 1,
			EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET);
}

/*
 * This function tries to merge the @ex extent to neighbours in the tree.
 * return 1 if merge left else 0.
 */
static void ext4_ext_try_to_merge(void *icb, handle_t *handle,
		struct inode *inode,
		struct ext4_ext_path *path,
		struct ext4_extent *ex) {
	struct ext4_extent_header *eh;
	unsigned int depth;
	int merge_done = 0;

	depth = ext_depth(inode);
	BUG_ON(path[depth].p_hdr == NULL);
	eh = path[depth].p_hdr;

	if (ex > EXT_FIRST_EXTENT(eh))
		merge_done = ext4_ext_try_to_merge_right(inode, path, ex - 1);

	if (!merge_done)
		(void) ext4_ext_try_to_merge_right(inode, path, ex);

	ext4_ext_try_to_merge_up(icb, handle, inode, path);
}

/*
 * ext4_ext_insert_extent:
 * tries to merge requsted extent into the existing extent or
 * inserts requested extent as new one into the tree,
 * creating new leaf in the no-space case.
 */
int ext4_ext_insert_extent(void *icb, handle_t *handle, struct inode *inode,
		struct ext4_ext_path **ppath,
		struct ext4_extent *newext,
		int gb_flags)
{
	struct ext4_ext_path *path = *ppath;
	struct ext4_extent_header *eh;
	struct ext4_extent *ex, *fex;
	struct ext4_extent *nearex; /* nearest extent */
	struct ext4_ext_path *npath = NULL;
	int depth, len, err;
	ext4_lblk_t next;
	int mb_flags = 0, unwritten;

	if (gb_flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
		mb_flags |= EXT4_MB_DELALLOC_RESERVED;
	if (unlikely(ext4_ext_get_actual_len(newext) == 0)) {
		EXT4_ERROR_INODE(inode, "ext4_ext_get_actual_len(newext) == 0");
		return -EIO;
	}
	depth = ext_depth(inode);
	ex = path[depth].p_ext;
	eh = path[depth].p_hdr;
	if (unlikely(path[depth].p_hdr == NULL)) {
		EXT4_ERROR_INODE(inode, "path[%d].p_hdr == NULL", depth);
		return -EIO;
	}

	/* try to insert block into found extent and return */
	if (ex && !(gb_flags & EXT4_GET_BLOCKS_PRE_IO)) {

		/*
		 * Try to see whether we should rather test the extent on
		 * right from ex, or from the left of ex. This is because
		 * ext4_find_extent() can return either extent on the
		 * left, or on the right from the searched position. This
		 * will make merging more effective.
		 */
		if (ex < EXT_LAST_EXTENT(eh) &&
				(le32_to_cpu(ex->ee_block) +
				 ext4_ext_get_actual_len(ex) <
				 le32_to_cpu(newext->ee_block))) {
			ex += 1;
			goto prepend;
		} else if ((ex > EXT_FIRST_EXTENT(eh)) &&
				(le32_to_cpu(newext->ee_block) +
				 ext4_ext_get_actual_len(newext) <
				 le32_to_cpu(ex->ee_block)))
			ex -= 1;

		/* Try to append newex to the ex */
		if (ext4_can_extents_be_merged(inode, ex, newext)) {
			ext_debug("append [%d]%d block to %u:[%d]%d"
					"(from %llu)\n",
					ext4_ext_is_unwritten(newext),
					ext4_ext_get_actual_len(newext),
					le32_to_cpu(ex->ee_block),
					ext4_ext_is_unwritten(ex),
					ext4_ext_get_actual_len(ex),
					ext4_ext_pblock(ex));
			err = ext4_ext_get_access(icb, handle, inode,
					path + depth);
			if (err)
				return err;
			unwritten = ext4_ext_is_unwritten(ex);
			ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
					+ ext4_ext_get_actual_len(newext));
			if (unwritten)
				ext4_ext_mark_unwritten(ex);
			eh = path[depth].p_hdr;
			nearex = ex;
			goto merge;
		}

prepend:
		/* Try to prepend newex to the ex */
		if (ext4_can_extents_be_merged(inode, newext, ex)) {
			ext_debug("prepend %u[%d]%d block to %u:[%d]%d"
					"(from %llu)\n",
					le32_to_cpu(newext->ee_block),
					ext4_ext_is_unwritten(newext),
					ext4_ext_get_actual_len(newext),
					le32_to_cpu(ex->ee_block),
					ext4_ext_is_unwritten(ex),
					ext4_ext_get_actual_len(ex),
					ext4_ext_pblock(ex));
			err = ext4_ext_get_access(icb, handle, inode,
					path + depth);
			if (err)
				return err;

			unwritten = ext4_ext_is_unwritten(ex);
			ex->ee_block = newext->ee_block;
			ext4_ext_store_pblock(ex, ext4_ext_pblock(newext));
			ex->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ex)
					+ ext4_ext_get_actual_len(newext));
			if (unwritten)
				ext4_ext_mark_unwritten(ex);
			eh = path[depth].p_hdr;
			nearex = ex;
			goto merge;
		}
	}

	depth = ext_depth(inode);
	eh = path[depth].p_hdr;
	if (le16_to_cpu(eh->eh_entries) < le16_to_cpu(eh->eh_max))
		goto has_space;

	/* probably next leaf has space for us? */
	fex = EXT_LAST_EXTENT(eh);
	next = EXT_MAX_BLOCKS;
	if (le32_to_cpu(newext->ee_block) > le32_to_cpu(fex->ee_block))
		next = ext4_ext_next_leaf_block(path);
	if (next != EXT_MAX_BLOCKS) {
		ext_debug("next leaf block - %u\n", next);
		BUG_ON(npath != NULL);
		npath = ext4_find_extent(inode, next, NULL, 0);
		if (IS_ERR(npath))
			return PTR_ERR(npath);
		BUG_ON(npath->p_depth != path->p_depth);
		eh = npath[depth].p_hdr;
		if (le16_to_cpu(eh->eh_entries) < le16_to_cpu(eh->eh_max)) {
			ext_debug("next leaf isn't full(%d)\n",
					le16_to_cpu(eh->eh_entries));
			path = npath;
			goto has_space;
		}
		ext_debug("next leaf has no free space(%d,%d)\n",
				le16_to_cpu(eh->eh_entries), le16_to_cpu(eh->eh_max));
	}

	/*
	 * There is no free space in the found leaf.
	 * We're gonna add a new leaf in the tree.
	 */
	if (gb_flags & EXT4_GET_BLOCKS_METADATA_NOFAIL)
		mb_flags |= EXT4_MB_USE_RESERVED;
	err = ext4_ext_create_new_leaf(icb, handle, inode, mb_flags, gb_flags,
			ppath, newext);
	if (err)
		goto cleanup;
	depth = ext_depth(inode);
	eh = path[depth].p_hdr;

has_space:
	nearex = path[depth].p_ext;

	err = ext4_ext_get_access(icb, handle, inode, path + depth);
	if (err)
		goto cleanup;

	if (!nearex) {
		/* there is no extent in this leaf, create first one */
		ext_debug("first extent in the leaf: %u:%llu:[%d]%d\n",
				le32_to_cpu(newext->ee_block),
				ext4_ext_pblock(newext),
				ext4_ext_is_unwritten(newext),
				ext4_ext_get_actual_len(newext));
		nearex = EXT_FIRST_EXTENT(eh);
	} else {
		if (le32_to_cpu(newext->ee_block)
				> le32_to_cpu(nearex->ee_block)) {
			/* Insert after */
			ext_debug("insert %u:%llu:[%d]%d before: "
					"nearest %p\n",
					le32_to_cpu(newext->ee_block),
					ext4_ext_pblock(newext),
					ext4_ext_is_unwritten(newext),
					ext4_ext_get_actual_len(newext),
					nearex);
			nearex++;
		} else {
			/* Insert before */
			BUG_ON(newext->ee_block == nearex->ee_block);
			ext_debug("insert %u:%llu:[%d]%d after: "
					"nearest %p\n",
					le32_to_cpu(newext->ee_block),
					ext4_ext_pblock(newext),
					ext4_ext_is_unwritten(newext),
					ext4_ext_get_actual_len(newext),
					nearex);
		}
		len = EXT_LAST_EXTENT(eh) - nearex + 1;
		if (len > 0) {
			ext_debug("insert %u:%llu:[%d]%d: "
					"move %d extents from 0x%p to 0x%p\n",
					le32_to_cpu(newext->ee_block),
					ext4_ext_pblock(newext),
					ext4_ext_is_unwritten(newext),
					ext4_ext_get_actual_len(newext),
					len, nearex, nearex + 1);
			memmove(nearex + 1, nearex,
					len * sizeof(struct ext4_extent));
		}
	}

	le16_add_cpu(&eh->eh_entries, 1);
	path[depth].p_ext = nearex;
	nearex->ee_block = newext->ee_block;
	ext4_ext_store_pblock(nearex, ext4_ext_pblock(newext));
	nearex->ee_len = newext->ee_len;

merge:
	/* try to merge extents */
	if (!(gb_flags & EXT4_GET_BLOCKS_PRE_IO))
		ext4_ext_try_to_merge(icb, handle, inode, path, nearex);


	/* time to correct all indexes above */
	err = ext4_ext_correct_indexes(icb, handle, inode, path);
	if (err)
		goto cleanup;

	err = ext4_ext_dirty(icb, handle, inode, path + path->p_depth);

cleanup:
	if (npath) {
		ext4_ext_drop_refs(npath);
		kfree(npath);
	}
	return err;
}

static inline int get_default_free_blocks_flags(struct inode *inode)
{
	return 0;
}

/* FIXME!! we need to try to merge to left or right after zero-out  */
static int ext4_ext_zeroout(struct inode *inode, struct ext4_extent *ex)
{
	ext4_fsblk_t ee_pblock;
	unsigned int ee_len;
	int ret;

	ee_len    = ext4_ext_get_actual_len(ex);
	ee_pblock = ext4_ext_pblock(ex);

	ret = 0;

	return ret;
}

static int ext4_remove_blocks(void *icb, handle_t *handle, struct inode *inode,
		struct ext4_extent *ex,
		unsigned long from, unsigned long to)
{
	struct buffer_head *bh;
	int i;

	if (from >= le32_to_cpu(ex->ee_block)
			&& to == le32_to_cpu(ex->ee_block) + ext4_ext_get_actual_len(ex) - 1) {
		/* tail removal */
		unsigned long num, start;
		num = le32_to_cpu(ex->ee_block) + ext4_ext_get_actual_len(ex) - from;
		start = ext4_ext_pblock(ex) + ext4_ext_get_actual_len(ex) - num;
		ext4_free_blocks(icb, handle, inode, NULL, start, num, 0);
	} else if (from == le32_to_cpu(ex->ee_block)
			&& to <= le32_to_cpu(ex->ee_block) + ext4_ext_get_actual_len(ex) - 1) {
	} else {
	}
	return 0;
}

/*
 * routine removes index from the index block
 * it's used in truncate case only. thus all requests are for
 * last index in the block only
 */
int ext4_ext_rm_idx(void *icb, handle_t *handle, struct inode *inode,
		struct ext4_ext_path *path)
{
	int err;
	ext4_fsblk_t leaf;

	/* free index block */
	path--;
	leaf = ext4_idx_pblock(path->p_idx);
	BUG_ON(path->p_hdr->eh_entries == 0);
	if ((err = ext4_ext_get_access(icb, handle, inode, path)))
		return err;
	path->p_hdr->eh_entries = cpu_to_le16(le16_to_cpu(path->p_hdr->eh_entries)-1);
	if ((err = ext4_ext_dirty(icb, handle, inode, path)))
		return err;
	ext4_free_blocks(icb, handle, inode, NULL, leaf, 1, 0);
	return err;
}

static int
ext4_ext_rm_leaf(void *icb, handle_t *handle, struct inode *inode,
		struct ext4_ext_path *path, unsigned long start)
{
	int err = 0, correct_index = 0;
	int depth = ext_depth(inode), credits;
	struct ext4_extent_header *eh;
	unsigned a, b, block, num;
	unsigned long ex_ee_block;
	unsigned short ex_ee_len;
	struct ext4_extent *ex;

	/* the header must be checked already in ext4_ext_remove_space() */
	if (!path[depth].p_hdr)
		path[depth].p_hdr = ext_block_hdr(path[depth].p_bh);
	eh = path[depth].p_hdr;
	BUG_ON(eh == NULL);

	/* find where to start removing */
	ex = EXT_LAST_EXTENT(eh);

	ex_ee_block = le32_to_cpu(ex->ee_block);
	ex_ee_len = ext4_ext_get_actual_len(ex);

	while (ex >= EXT_FIRST_EXTENT(eh) &&
			ex_ee_block + ex_ee_len > start) {
		path[depth].p_ext = ex;

		a = ex_ee_block > start ? ex_ee_block : start;
		b = (unsigned long long)ex_ee_block + ex_ee_len - 1 <
			EXT_MAX_BLOCKS ? ex_ee_block + ex_ee_len - 1 : EXT_MAX_BLOCKS;


		if (a != ex_ee_block && b != ex_ee_block + ex_ee_len - 1) {
			block = 0;
			num = 0;
			BUG();
		} else if (a != ex_ee_block) {
			/* remove tail of the extent */
			block = ex_ee_block;
			num = a - block;
		} else if (b != ex_ee_block + ex_ee_len - 1) {
			/* remove head of the extent */
			block = a;
			num = b - a;
			/* there is no "make a hole" API yet */
			BUG();
		} else {
			/* remove whole extent: excellent! */
			block = ex_ee_block;
			num = 0;
			BUG_ON(a != ex_ee_block);
			BUG_ON(b != ex_ee_block + ex_ee_len - 1);
		}

		/* at present, extent can't cross block group */
		/* leaf + bitmap + group desc + sb + inode */
		credits = 5;
		if (ex == EXT_FIRST_EXTENT(eh)) {
			correct_index = 1;
			credits += (ext_depth(inode)) + 1;
		}

		/*handle = ext4_ext_journal_restart(icb, handle, credits);*/
		/*if (IS_ERR(icb, handle)) {*/
		/*err = PTR_ERR(icb, handle);*/
		/*goto out;*/
		/*}*/

		err = ext4_ext_get_access(icb, handle, inode, path + depth);
		if (err)
			goto out;

		err = ext4_remove_blocks(icb, handle, inode, ex, a, b);
		if (err)
			goto out;

		if (num == 0) {
			/* this extent is removed entirely mark slot unused */
			ext4_ext_store_pblock(ex, 0);
			eh->eh_entries = cpu_to_le16(le16_to_cpu(eh->eh_entries)-1);
		}

		ex->ee_block = cpu_to_le32(block);
		ex->ee_len = cpu_to_le16(num);

		err = ext4_ext_dirty(icb, handle, inode, path + depth);
		if (err)
			goto out;

		ex--;
		ex_ee_block = le32_to_cpu(ex->ee_block);
		ex_ee_len = ext4_ext_get_actual_len(ex);
	}

	if (correct_index && eh->eh_entries)
		err = ext4_ext_correct_indexes(icb, handle, inode, path);

	/* if this leaf is free, then we should
	 * remove it from index block above */
	if (err == 0 && eh->eh_entries == 0 && path[depth].p_bh != NULL)
		err = ext4_ext_rm_idx(icb, handle, inode, path + depth);

out:
	return err;
}

/*
 * ext4_split_extent_at() splits an extent at given block.
 *
 * @handle: the journal handle
 * @inode: the file inode
 * @path: the path to the extent
 * @split: the logical block where the extent is splitted.
 * @split_flags: indicates if the extent could be zeroout if split fails, and
 *		 the states(init or unwritten) of new extents.
 * @flags: flags used to insert new extent to extent tree.
 *
 *
 * Splits extent [a, b] into two extents [a, @split) and [@split, b], states
 * of which are deterimined by split_flag.
 *
 * There are two cases:
 *  a> the extent are splitted into two extent.
 *  b> split is not needed, and just mark the extent.
 *
 * return 0 on success.
 */
static int ext4_split_extent_at(void *icb, handle_t *handle,
		struct inode *inode,
		struct ext4_ext_path **ppath,
		ext4_lblk_t split,
		int split_flag,
		int flags)
{
	struct ext4_ext_path *path = *ppath;
	ext4_fsblk_t newblock;
	ext4_lblk_t ee_block;
	struct ext4_extent *ex, newex, orig_ex, zero_ex;
	struct ext4_extent *ex2 = NULL;
	unsigned int ee_len, depth;
	int err = 0;

	ext4_ext_show_leaf(inode, path);

	depth = ext_depth(inode);
	ex = path[depth].p_ext;
	ee_block = le32_to_cpu(ex->ee_block);
	ee_len = ext4_ext_get_actual_len(ex);
	newblock = split - ee_block + ext4_ext_pblock(ex);

	BUG_ON(split < ee_block || split >= (ee_block + ee_len));

	err = ext4_ext_get_access(icb, handle, inode, path + depth);
	if (err)
		goto out;

	if (split == ee_block) {
		/*
		 * case b: block @split is the block that the extent begins with
		 * then we just change the state of the extent, and splitting
		 * is not needed.
		 */
		if (split_flag & EXT4_EXT_MARK_UNWRIT2)
			ext4_ext_mark_unwritten(ex);
		else
			ext4_ext_mark_initialized(ex);

		if (!(flags & EXT4_GET_BLOCKS_PRE_IO))
			ext4_ext_try_to_merge(icb, handle, inode, path, ex);

		err = ext4_ext_dirty(icb, handle, inode, path + path->p_depth);
		goto out;
	}

	/* case a */
	memcpy(&orig_ex, ex, sizeof(orig_ex));
	ex->ee_len = cpu_to_le16(split - ee_block);
	if (split_flag & EXT4_EXT_MARK_UNWRIT1)
		ext4_ext_mark_unwritten(ex);

	/*
	 * path may lead to new leaf, not to original leaf any more
	 * after ext4_ext_insert_extent() returns,
	 */
	err = ext4_ext_dirty(icb, handle, inode, path + depth);
	if (err)
		goto fix_extent_len;

	ex2 = &newex;
	ex2->ee_block = cpu_to_le32(split);
	ex2->ee_len   = cpu_to_le16(ee_len - (split - ee_block));
	ext4_ext_store_pblock(ex2, newblock);
	if (split_flag & EXT4_EXT_MARK_UNWRIT2)
		ext4_ext_mark_unwritten(ex2);

	err = ext4_ext_insert_extent(icb, handle, inode, ppath, &newex, flags);
	if (err == -ENOSPC && (EXT4_EXT_MAY_ZEROOUT & split_flag)) {
		if (split_flag & (EXT4_EXT_DATA_VALID1|EXT4_EXT_DATA_VALID2)) {
			if (split_flag & EXT4_EXT_DATA_VALID1) {
				err = ext4_ext_zeroout(inode, ex2);
				zero_ex.ee_block = ex2->ee_block;
				zero_ex.ee_len = cpu_to_le16(
						ext4_ext_get_actual_len(ex2));
				ext4_ext_store_pblock(&zero_ex,
						ext4_ext_pblock(ex2));
			} else {
				err = ext4_ext_zeroout(inode, ex);
				zero_ex.ee_block = ex->ee_block;
				zero_ex.ee_len = cpu_to_le16(
						ext4_ext_get_actual_len(ex));
				ext4_ext_store_pblock(&zero_ex,
						ext4_ext_pblock(ex));
			}
		} else {
			err = ext4_ext_zeroout(inode, &orig_ex);
			zero_ex.ee_block = orig_ex.ee_block;
			zero_ex.ee_len = cpu_to_le16(
					ext4_ext_get_actual_len(&orig_ex));
			ext4_ext_store_pblock(&zero_ex,
					ext4_ext_pblock(&orig_ex));
		}

		if (err)
			goto fix_extent_len;
		/* update the extent length and mark as initialized */
		ex->ee_len = cpu_to_le16(ee_len);
		ext4_ext_try_to_merge(icb, handle, inode, path, ex);
		err = ext4_ext_dirty(icb, handle, inode, path + path->p_depth);
		if (err)
			goto fix_extent_len;

		goto out;
	} else if (err)
		goto fix_extent_len;

out:
	ext4_ext_show_leaf(inode, path);
	return err;

fix_extent_len:
	ex->ee_len = orig_ex.ee_len;
	ext4_ext_dirty(icb, handle, inode, path + path->p_depth);
	return err;
}

/*
 * returns 1 if current index have to be freed (even partial)
 */
#ifndef __REACTOS__
static int inline
#else
inline int
#endif
ext4_ext_more_to_rm(struct ext4_ext_path *path)
{
	BUG_ON(path->p_idx == NULL);

	if (path->p_idx < EXT_FIRST_INDEX(path->p_hdr))
		return 0;

	/*
	 * if truncate on deeper level happened it it wasn't partial
	 * so we have to consider current index for truncation
	 */
	if (le16_to_cpu(path->p_hdr->eh_entries) == path->p_block)
		return 0;
	return 1;
}

int ext4_ext_remove_space(void *icb, struct inode *inode, unsigned long start)
{
	struct super_block *sb = inode->i_sb;
	int depth = ext_depth(inode);
	struct ext4_ext_path *path;
	handle_t *handle = NULL;
	int i = 0, err = 0;

	/* probably first extent we're gonna free will be last in block */
	/*handle = ext4_journal_start(inode, depth + 1);*/
	/*if (IS_ERR(icb, handle))*/
	/*return PTR_ERR(icb, handle);*/

	/*
	 * we start scanning from right side freeing all the blocks
	 * after i_size and walking into the deep
	 */
	path = kmalloc(sizeof(struct ext4_ext_path) * (depth + 1), GFP_KERNEL);
	if (path == NULL) {
		ext4_journal_stop(icb, handle);
		return -ENOMEM;
	}
	memset(path, 0, sizeof(struct ext4_ext_path) * (depth + 1));
	path[0].p_hdr = ext_inode_hdr(inode);
	if (ext4_ext_check_inode(inode)) {
		err = -EIO;
		goto out;
	}
	path[0].p_depth = depth;

	while (i >= 0 && err == 0) {
		if (i == depth) {
			/* this is leaf block */
			err = ext4_ext_rm_leaf(icb, handle, inode, path, start);
			/* root level have p_bh == NULL, extents_brelse() eats this */
			extents_brelse(path[i].p_bh);
			path[i].p_bh = NULL;
			i--;
			continue;
		}

		/* this is index block */
		if (!path[i].p_hdr) {
			path[i].p_hdr = ext_block_hdr(path[i].p_bh);
		}

		if (!path[i].p_idx) {
			/* this level hasn't touched yet */
			path[i].p_idx = EXT_LAST_INDEX(path[i].p_hdr);
			path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries)+1;
		} else {
			/* we've already was here, see at next index */
			path[i].p_idx--;
		}

		if (ext4_ext_more_to_rm(path + i)) {
			struct buffer_head *bh;
			/* go to the next level */
			memset(path + i + 1, 0, sizeof(*path));
			bh = read_extent_tree_block(inode, ext4_idx_pblock(path[i].p_idx), path[0].p_depth - (i + 1), 0);
			if (IS_ERR(bh)) {
				/* should we reset i_size? */
				err = -EIO;
				break;
			}
			path[i+1].p_bh = bh;

			/* put actual number of indexes to know is this
			 * number got changed at the next iteration */
			path[i].p_block = le16_to_cpu(path[i].p_hdr->eh_entries);
			i++;
		} else {
			/* we finish processing this index, go up */
			if (path[i].p_hdr->eh_entries == 0 && i > 0) {
				/* index is empty, remove it
				 * handle must be already prepared by the
				 * truncatei_leaf() */
				err = ext4_ext_rm_idx(icb, handle, inode, path + i);
			}
			/* root level have p_bh == NULL, extents_brelse() eats this */
			extents_brelse(path[i].p_bh);
			path[i].p_bh = NULL;
			i--;
		}
	}

	/* TODO: flexible tree reduction should be here */
	if (path->p_hdr->eh_entries == 0) {
		/*
		 * truncate to zero freed all the tree
		 * so, we need to correct eh_depth
		 */
		err = ext4_ext_get_access(icb, handle, inode, path);
		if (err == 0) {
			ext_inode_hdr(inode)->eh_depth = 0;
			ext_inode_hdr(inode)->eh_max =
				cpu_to_le16(ext4_ext_space_root(inode, 0));
			err = ext4_ext_dirty(icb, handle, inode, path);
		}
	}
out:
	if (path) {
		ext4_ext_drop_refs(path);
		kfree(path);
	}
	ext4_journal_stop(icb, handle);

	return err;
}

int ext4_ext_tree_init(void *icb, handle_t *handle, struct inode *inode)
{
	struct ext4_extent_header *eh;

	eh = ext_inode_hdr(inode);
	eh->eh_depth = 0;
	eh->eh_entries = 0;
	eh->eh_magic = cpu_to_le16(EXT4_EXT_MAGIC);
	eh->eh_max = cpu_to_le16(ext4_ext_space_root(inode, 0));
	ext4_mark_inode_dirty(icb, handle, inode);
	return 0;
}

/*
 * called at mount time
 */
void ext4_ext_init(struct super_block *sb)
{
	/*
	 * possible initialization would be here
	 */
}

static int ext4_ext_convert_to_initialized (
		void *icb,
		handle_t *handle,
		struct inode *inode,
		struct ext4_ext_path **ppath,
		ext4_lblk_t split,
		unsigned long blocks,
		int flags)
{
	int depth = ext_depth(inode), err;
	struct ext4_extent *ex = (*ppath)[depth].p_ext;

	assert (le32_to_cpu(ex->ee_block) <= split);

	if (split + blocks == le32_to_cpu(ex->ee_block) +
						  ext4_ext_get_actual_len(ex)) {

		/* split and initialize right part */
		err = ext4_split_extent_at(icb, handle, inode, ppath, split,
								   EXT4_EXT_MARK_UNWRIT1, flags);

	} else if (le32_to_cpu(ex->ee_block) == split) {

		/* split and initialize left part */
		err = ext4_split_extent_at(icb, handle, inode, ppath, split + blocks,
								   EXT4_EXT_MARK_UNWRIT2, flags);

	} else {

		/* split 1 extent to 3 and initialize the 2nd */
		err = ext4_split_extent_at(icb, handle, inode, ppath, split + blocks,
								   EXT4_EXT_MARK_UNWRIT1 |
								   EXT4_EXT_MARK_UNWRIT2, flags);
		if (0 == err) {
			err = ext4_split_extent_at(icb, handle, inode, ppath, split,
									   EXT4_EXT_MARK_UNWRIT1, flags);
		}
	}

	return err;
}

int ext4_ext_get_blocks(void *icb, handle_t *handle, struct inode *inode, ext4_fsblk_t iblock,
		unsigned long max_blocks, struct buffer_head *bh_result,
		int create, int flags)
{
	struct ext4_ext_path *path = NULL;
	struct ext4_extent newex, *ex;
	int goal, err = 0, depth;
	unsigned long allocated = 0;
	ext4_fsblk_t next, newblock;

	clear_buffer_new(bh_result);
	/*mutex_lock(&ext4_I(inode)->truncate_mutex);*/

	/* find extent for this block */
	path = ext4_find_extent(inode, iblock, NULL, 0);
	if (IS_ERR(path)) {
		err = PTR_ERR(path);
		path = NULL;
		goto out2;
	}

	depth = ext_depth(inode);

	/*
	 * consistent leaf must not be empty
	 * this situations is possible, though, _during_ tree modification
	 * this is why assert can't be put in ext4_ext_find_extent()
	 */
	BUG_ON(path[depth].p_ext == NULL && depth != 0);

	if ((ex = path[depth].p_ext)) {
		ext4_lblk_t ee_block = le32_to_cpu(ex->ee_block);
		ext4_fsblk_t ee_start = ext4_ext_pblock(ex);
		unsigned short ee_len  = ext4_ext_get_actual_len(ex);
		/* if found exent covers block, simple return it */
		if (iblock >= ee_block && iblock < ee_block + ee_len) {

			/* number of remain blocks in the extent */
			allocated = ee_len + ee_block - iblock;

			if (ext4_ext_is_unwritten(ex)) {
				if (create) {
					newblock = iblock - ee_block + ee_start;
					err = ext4_ext_convert_to_initialized (
							icb, handle,
							inode,
							&path,
							iblock,
							allocated,
							flags);
					if (err)
						goto out2;

				} else {
					newblock = 0;
				}
			} else {
				newblock = iblock - ee_block + ee_start;
			}
			goto out;
		}
	}

	/*
	 * requested block isn't allocated yet
	 * we couldn't try to create block if create flag is zero
	 */
	if (!create) {
		goto out2;
	}

	/* find next allocated block so that we know how many
	 * blocks we can allocate without ovelapping next extent */
	next = ext4_ext_next_allocated_block(path);
	BUG_ON(next <= iblock);
	allocated = next - iblock;
	if (flags & EXT4_GET_BLOCKS_PRE_IO && max_blocks > EXT_UNWRITTEN_MAX_LEN)
		max_blocks = EXT_UNWRITTEN_MAX_LEN;
	if (allocated > max_blocks)
		allocated = max_blocks;

	/* allocate new block */
	goal = ext4_ext_find_goal(inode, path, iblock);

	newblock = ext4_new_meta_blocks(icb, handle, inode, goal, 0,
			&allocated, &err);
	if (!newblock)
		goto out2;

	/* try to insert new extent into found leaf and return */
	newex.ee_block = cpu_to_le32(iblock);
	ext4_ext_store_pblock(&newex, newblock);
	newex.ee_len = cpu_to_le16(allocated);
	/* if it's fallocate, mark ex as unwritten */
	if (flags & EXT4_GET_BLOCKS_PRE_IO) {
		ext4_ext_mark_unwritten(&newex);
	}
	err = ext4_ext_insert_extent(icb, handle, inode, &path, &newex,
                                 flags & EXT4_GET_BLOCKS_PRE_IO);

	if (err) {
		/* free data blocks we just allocated */
		ext4_free_blocks(icb, handle, inode, NULL, ext4_ext_pblock(&newex),
				le16_to_cpu(newex.ee_len), get_default_free_blocks_flags(inode));
		goto out2;
	}

	ext4_mark_inode_dirty(icb, handle, inode);

	/* previous routine could use block we allocated */
	if (ext4_ext_is_unwritten(&newex))
		newblock = 0;
	else
		newblock = ext4_ext_pblock(&newex);

	set_buffer_new(bh_result);

out:
	if (allocated > max_blocks)
		allocated = max_blocks;

	ext4_ext_show_leaf(inode, path);
	set_buffer_mapped(bh_result);
	bh_result->b_bdev = inode->i_sb->s_bdev;
	bh_result->b_blocknr = newblock;
out2:
	if (path) {
		ext4_ext_drop_refs(path);
		kfree(path);
	}
	/*mutex_unlock(&ext4_I(inode)->truncate_mutex);*/

	return err ? err : allocated;
}

int ext4_ext_truncate(void *icb, struct inode *inode, unsigned long start)
{
    int ret = ext4_ext_remove_space(icb, inode, start);

	/* Save modifications on i_blocks field of the inode. */
	if (!ret)
		ret = ext4_mark_inode_dirty(icb, NULL, inode);

	return ret;
}

#ifdef _MSC_VER
#pragma warning(pop)
#endif