e2fsprogs: Add ext4migrate

new file mode 100644
index 0000000..d25ce36
@@ -0,0 +1,763 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "migrate.h"
+#include "extents.h"
+
+struct ext4_ext_path {
+	ext4_fsblk_t			p_block;
+	__u16				p_depth;
+	struct ext3_extent		*p_ext;
+	struct ext3_extent_idx		*p_idx;
+	struct ext3_extent_header	*p_hdr;
+};
+
+/*
+ * ext_pblock:
+ * combine low and high parts of physical block number into ext4_fsblk_t
+ */
+ext4_fsblk_t ext_pblock(struct ext3_extent *ex)
+{
+	ext4_fsblk_t block;
+
+	block = ex->ee_start;
+	block |= ((ext4_fsblk_t) ex->ee_start_hi << 31) << 1;
+	return block;
+}
+
+/*
+ * idx_pblock:
+ * combine low and high parts of a leaf physical block number into ext4_fsblk_t
+ */
+ext4_fsblk_t idx_pblock(struct ext3_extent_idx *ix)
+{
+	ext4_fsblk_t block;
+
+	block = ix->ei_leaf;
+	block |= ((ext4_fsblk_t) ix->ei_leaf_hi << 31) << 1;
+	return block;
+}
+
+/*
+ * ext3_ext_store_pblock:
+ * stores a large physical block number into an extent struct,
+ * breaking it into parts
+ */
+void ext3_ext_store_pblock(struct ext3_extent *ex, ext4_fsblk_t pb)
+{
+	ex->ee_start = (unsigned long) (pb & 0xffffffff);
+	ex->ee_start_hi = (unsigned long) ((pb >> 31) >> 1) & 0xffff;
+}
+
+/*
+ * ext3_idx_store_pblock:
+ * stores a large physical block number into an index struct,
+ * breaking it into parts
+ */
+static void ext3_idx_store_pblock(struct ext3_extent_idx *ix, ext4_fsblk_t pb)
+{
+	ix->ei_leaf = (unsigned long) (pb & 0xffffffff);
+	ix->ei_leaf_hi = (unsigned long) ((pb >> 31) >> 1) & 0xffff;
+}
+
+
+static int __ext3_ext_space_block(ext2_filsys filesys)
+{
+	int size;
+
+	size = (filesys->blocksize - sizeof(struct ext3_extent_header))
+			/ sizeof(struct ext3_extent);
+	return size;
+}
+static int ext3_ext_space_block()
+{
+	return  __ext3_ext_space_block(current_fs);
+}
+
+static int __ext3_ext_space_block_idx(ext2_filsys filesys)
+{
+	int size;
+
+	size = (filesys->blocksize - sizeof(struct ext3_extent_header))
+			/ sizeof(struct ext3_extent_idx);
+	return size;
+}
+static int ext3_ext_space_block_idx()
+{
+	return __ext3_ext_space_block_idx(current_fs);
+
+}
+
+int ext3_ext_space_root(void)
+{
+	int size;
+
+	size = EXT2_N_BLOCKS*sizeof(blk_t);
+	size -= sizeof(struct ext3_extent_header);
+	size /= sizeof(struct ext3_extent);
+	return size;
+}
+
+static int ext3_ext_space_root_idx(void)
+{
+	int size;
+
+	size = EXT2_N_BLOCKS*sizeof(blk_t);
+	size -= sizeof(struct ext3_extent_header);
+	size /= sizeof(struct ext3_extent_idx);
+	return size;
+}
+static void ext3_ext_binsearch_idx(struct ext4_ext_path *path,
+						blk_t logical_blk)
+{
+	struct ext3_extent_header *eh = path->p_hdr;
+	struct ext3_extent_idx *r, *l, *m;
+
+	l = EXT_FIRST_INDEX(eh) + 1;
+	r = EXT_FIRST_INDEX(eh) + eh->eh_entries - 1;
+	while (l <= r) {
+		m = l + (r - l) / 2;
+		if (logical_blk < m->ei_block)
+			r = m - 1;
+		else
+			l = m + 1;
+	}
+	path->p_idx = l - 1;
+}
+
+static void ext3_ext_binsearch(struct ext4_ext_path *path, blk_t logical_blk)
+{
+	struct ext3_extent_header *eh = path->p_hdr;
+	struct ext3_extent *r, *l, *m;
+
+	if (eh->eh_entries == 0) {
+		/*
+		 * this leaf is empty:
+		 * we get such a leaf in split/add case
+		 */
+		return;
+	}
+
+	l = EXT_FIRST_EXTENT(eh) + 1;
+	r = EXT_FIRST_EXTENT(eh) + eh->eh_entries - 1;
+
+	while (l <= r) {
+		m = l + (r - l) / 2;
+		if (logical_blk < m->ee_block)
+			r = m - 1;
+		else
+			l = m + 1;
+	}
+
+	path->p_ext = l - 1;
+}
+
+/*
+ * ext3_ext_insert_index:
+ * insert new index [@logical;@ptr] into the block at @curp;
+ * check where to insert: before @curp or after @curp
+ */
+static int ext3_ext_insert_index(struct ext4_ext_path *curp,
+				int logical, ext4_fsblk_t ptr)
+{
+	struct ext3_extent_idx *ix;
+	int len, err = 0;
+
+	len = EXT_MAX_INDEX(curp->p_hdr) - curp->p_idx;
+	if (logical > curp->p_idx->ei_block) {
+		/* insert after */
+		if (curp->p_idx != EXT_LAST_INDEX(curp->p_hdr)) {
+			len = (len - 1) * sizeof(struct ext3_extent_idx);
+			len = len < 0 ? 0 : len;
+			memmove(curp->p_idx + 2, curp->p_idx + 1, len);
+		}
+		ix = curp->p_idx + 1;
+	} else {
+		/* insert before */
+		len = len * sizeof(struct ext3_extent_idx);
+		len = len < 0 ? 0 : len;
+		memmove(curp->p_idx + 1, curp->p_idx, len);
+		ix = curp->p_idx;
+	}
+
+	ix->ei_block = logical;
+	ext3_idx_store_pblock(ix, ptr);
+	curp->p_hdr->eh_entries = curp->p_hdr->eh_entries+1;
+
+	return err;
+}
+/*
+ * ext3_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 ext3_ext_split(struct ext3_extent_header *eh,
+				struct ext4_ext_path *path,
+				struct ext3_extent *newext, int at)
+{
+	int depth = eh->eh_depth;
+	struct ext3_extent_header *neh;
+	struct ext3_extent_idx *fidx;
+	struct ext3_extent *ex;
+	struct blk_cache *blkc;
+	int i = at, k, m, a;
+	ext4_fsblk_t newblock, oldblock;
+	int 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 (path[depth].p_ext != EXT_MAX_EXTENT(path[depth].p_hdr)) {
+		border = path[depth].p_ext[1].ee_block;
+	} else {
+		border = newext->ee_block;
+	}
+
+	/*
+	 * 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 = malloc(sizeof(ext4_fsblk_t) * depth);
+	if (!ablocks)
+		return -1;
+
+	memset(ablocks, 0, sizeof(ext4_fsblk_t) * depth);
+
+	/* allocate all needed blocks */
+	for (a = 0; a < depth - at; a++) {
+		blkc = get_block(0);
+		if (!blkc) {
+			err =  EXT2_ET_BLOCK_ALLOC_FAIL;
+			goto cleanup;
+		}
+		newblock = blkc->pblock;
+		if (newblock == 0)
+			goto cleanup;
+		ablocks[a] = newblock;
+	}
+
+	/* initialize new leaf */
+	newblock = ablocks[--a];
+
+	blkc = get_block(newblock);
+	if (!blkc) {
+		err =  EXT2_ET_BLOCK_ALLOC_FAIL;
+		goto cleanup;
+	}
+
+	neh = (struct ext3_extent_header *)blkc->block_mem_addr;
+	neh->eh_entries = 0;
+	neh->eh_max = ext3_ext_space_block();
+	neh->eh_magic = EXT4_EXT_MAGIC;
+	neh->eh_depth = 0;
+	ex = EXT_FIRST_EXTENT(neh);
+
+	/* move remainder of path[depth] to the new leaf */
+	/* start copy from next extent */
+	/* TODO: we could do it by single memmove */
+	m = 0;
+	path[depth].p_ext++;
+	while (path[depth].p_ext <=
+			EXT_MAX_EXTENT(path[depth].p_hdr)) {
+		/*memmove(ex++, path[depth].p_ext++,
+				sizeof(struct ext4_extent));
+		neh->eh_entries++;*/
+		path[depth].p_ext++;
+		m++;
+	}
+
+	/*
+	 * move the part of the old extent to the new allocated one
+	 */
+	if (m) {
+		memmove(ex, path[depth].p_ext-m, sizeof(struct ext3_extent)*m);
+		neh->eh_entries = neh->eh_entries+m;
+	}
+
+	/* correct old leaf */
+	if (m) {
+		path[depth].p_hdr->eh_entries = path[depth].p_hdr->eh_entries-m;
+
+	}
+
+	/* create intermediate indexes */
+	k = depth - at - 1;
+
+	/*create intermediate indices */
+	/* insert new index into current index block */
+	/* current depth stored in i var */
+	i = depth - 1;
+	while (k--) {
+		oldblock = newblock;
+		newblock = ablocks[--a];
+		blkc = get_block(newblock);
+		if (!blkc) {
+			err =  EXT2_ET_BLOCK_ALLOC_FAIL;
+			goto cleanup;
+		}
+
+		neh = (struct ext3_extent_header *)blkc->block_mem_addr;
+
+		neh->eh_entries = 1;
+		neh->eh_magic = EXT4_EXT_MAGIC;
+		neh->eh_max = ext3_ext_space_block_idx();
+		neh->eh_depth = depth - i;
+		fidx = EXT_FIRST_INDEX(neh);
+		fidx->ei_block = border;
+		ext3_idx_store_pblock(fidx, oldblock);
+
+		/* copy indexes */
+		m = 0;
+		path[i].p_idx++;
+
+		while (path[i].p_idx <= EXT_MAX_INDEX(path[i].p_hdr)) {
+			/*memmove(++fidx, path[i].p_idx++,
+					sizeof(struct ext4_extent_idx));
+			neh->eh_entries++;
+			BUG_ON(neh->eh_entries > neh->eh_max);*/
+			path[i].p_idx++;
+			m++;
+		}
+		if (m) {
+			memmove(++fidx, path[i].p_idx - m,
+				sizeof(struct ext3_extent_idx) * m);
+			neh->eh_entries = neh->eh_entries + m;
+		}
+
+
+		/* correct old index */
+		if (m) {
+			path[i].p_hdr->eh_entries = path[i].p_hdr->eh_entries-m;
+		}
+
+		i--;
+	}
+
+	/* insert new index */
+	err = ext3_ext_insert_index(path + at, border, newblock);
+
+cleanup:
+
+	free(ablocks);
+
+	return err;
+}
+
+/*
+ * ext3_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 ext3_ext_grow_indepth(struct ext3_extent_header *eh,
+					struct ext4_ext_path *path)
+{
+	struct ext4_ext_path *curp = path;
+	struct ext3_extent_header *neh;
+	struct blk_cache *blkc;
+	ext4_fsblk_t newblock;
+	void *addr;
+
+	blkc = get_block(0);
+	if (!blkc) {
+		return  EXT2_ET_BLOCK_ALLOC_FAIL;
+
+	}
+	addr = blkc->block_mem_addr;
+	newblock = blkc->pblock;
+
+	/* move top-level index/leaf into new block */
+	memmove(addr, curp->p_hdr, EXT2_N_BLOCKS*sizeof(blk_t));
+
+	/* set size of new block */
+	neh =  (struct ext3_extent_header *)addr;
+	/* old root could have indexes or leaves
+	 * so calculate e_max right way */
+	if (eh->eh_depth) {
+		neh->eh_max = ext3_ext_space_block_idx();
+	} else {
+		neh->eh_max = ext3_ext_space_block();
+	}
+
+	neh->eh_magic = EXT4_EXT_MAGIC;
+
+	/* create index in new top-level index: num,max,pointer */
+
+	curp->p_hdr->eh_magic = EXT4_EXT_MAGIC;
+	curp->p_hdr->eh_max = ext3_ext_space_root_idx();
+	curp->p_hdr->eh_entries = 1;
+	curp->p_idx = EXT_FIRST_INDEX(curp->p_hdr);
+	/* FIXME: it works, but actually path[0] can be index */
+	curp->p_idx->ei_block = EXT_FIRST_EXTENT(path[0].p_hdr)->ee_block;
+	ext3_idx_store_pblock(curp->p_idx, newblock);
+
+	neh = eh;
+	//fidx = EXT_FIRST_INDEX(neh);
+
+	neh->eh_depth = path->p_depth + 1;
+
+	return 0;
+}
+struct ext4_ext_path * ext3_ext_find_extent(struct ext3_extent_header *eh,
+						blk_t logical_blk,
+						struct ext4_ext_path *path)
+{
+
+	struct blk_cache *blkc;
+	short int depth, i, ppos = 0;
+	int alloc = 0;
+
+	i = depth =  eh->eh_depth;
+
+	if (!path) {
+		/*
+		 * We may be called to rebuild the path while growing the
+		 * depth of the tree
+		 */
+		path = malloc(sizeof(struct ext4_ext_path)* (depth+2));
+		if (!path)
+			return NULL;
+
+		alloc = 1;
+		memset(path, 0, sizeof(struct ext4_ext_path)* (depth+2));
+	}
+
+
+	path[0].p_hdr = eh;
+
+	while (i) {
+
+		ext3_ext_binsearch_idx(path+ppos, logical_blk);
+
+		path[ppos].p_block = idx_pblock(path[ppos].p_idx);
+		path[ppos].p_depth = i;
+		path[ppos].p_ext = NULL;
+
+		blkc = get_block(path[ppos].p_block);
+
+		if (!blkc) {
+			if (alloc)
+				free(path);
+			return NULL;
+		}
+
+		eh = blkc->block_mem_addr;
+		if (!eh) {
+			if (alloc)
+				free(path);
+			return NULL;
+		}
+		if (eh->eh_max == 0) {
+			if (alloc)
+				free(path);
+			return NULL;
+		}
+		ppos++;
+		path[ppos].p_hdr = eh;
+		i--;
+	}
+	path[ppos].p_depth = i;
+	path[ppos].p_hdr = eh;
+	path[ppos].p_ext = NULL;
+	path[ppos].p_idx = NULL;
+
+	ext3_ext_binsearch(path + ppos, logical_blk);
+
+	return path;
+}
+
+static int ext3_ext_create_new_leaf(struct ext3_extent_header *eh,
+					struct ext4_ext_path *path,
+					struct ext3_extent *newext)
+{
+
+	struct ext4_ext_path *curp;
+	int depth, i, err = 0;
+
+repeat:
+	i = depth = eh->eh_depth;
+
+	/* walk up to the tree and look for free index entry */
+	curp = path + depth;
+	while (i > 0 && !EXT_HAS_FREE_INDEX(curp)) {
+		i--;
+		curp--;
+	}
+
+	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 = ext3_ext_split(eh, path, newext, i);
+		if (err)
+			goto err_out;
+
+		/*
+		 * Recalculate the path since grow inode would
+		 * have changed it
+		 */
+		path = ext3_ext_find_extent(eh, newext->ee_block, path);
+		if (!path) {
+			err = EXT2_ET_BLOCK_ALLOC_FAIL;
+			goto err_out;
+		}
+
+	} else {
+
+		/* tree is full, time to grow in depth */
+		err = ext3_ext_grow_indepth(eh, path);
+		if (err)
+			goto err_out;
+
+		/*
+		 * recalculate the path since grow inode
+		 * would have changed it i
+		 */
+		path = ext3_ext_find_extent(eh, newext->ee_block, path);
+		if (!path) {
+			err = EXT2_ET_BLOCK_ALLOC_FAIL;
+			goto err_out;
+		}
+
+
+		/*
+		 * only first (depth 0 -> 1) produces free space;
+		 * in all other cases we have to split the grown tree
+		 */
+		depth = eh->eh_depth;
+		if (path[depth].p_hdr->eh_entries == path[depth].p_hdr->eh_max) {
+			/* now we need to split */
+			goto repeat;
+		}
+
+	}
+
+err_out:
+
+	return err;
+}
+
+static int ext3_can_extents_be_merged(struct ext3_extent *ex1,
+					struct ext3_extent *ex2)
+{
+	if (ex1->ee_block + ex1->ee_len != ex2->ee_block)
+		return 0;
+
+
+	if (ext_pblock(ex1) + ex1->ee_len == ext_pblock(ex2))
+		return 1;
+	return 0;
+}
+
+
+/*
+ * ext3_ext_next_leaf_block:
+ * returns first allocated block from next leaf or EXT_MAX_BLOCK
+ */
+static unsigned ext3_ext_next_leaf_block(struct ext4_ext_path *path)
+{
+	int depth;
+
+	depth = path->p_depth;
+
+	/* zero-tree has no leaf blocks at all */
+	if (depth == 0)
+		return EXT_MAX_BLOCK;
+
+	/* go to index block */
+	depth--;
+
+	while (depth >= 0) {
+		if (path[depth].p_idx != EXT_LAST_INDEX(path[depth].p_hdr)) {
+			return path[depth].p_idx[1].ei_block;
+		}
+		depth--;
+	}
+
+	return EXT_MAX_BLOCK;
+}
+
+/*
+ * ext3_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 void ext3_ext_correct_indexes(struct ext3_extent_header *eh,
+					struct ext4_ext_path *path)
+{
+	int depth = eh->eh_depth;
+	struct ext3_extent *ex;
+	int border;
+	int k;
+
+
+	eh = path[depth].p_hdr;
+	ex = path[depth].p_ext;
+
+	if (depth == 0) {
+		/* there is no tree at all */
+		return;
+	}
+
+	if (ex != EXT_FIRST_EXTENT(eh)) {
+		/* we correct tree if first leaf got modified only */
+		return;
+	}
+
+	/*
+	 * TODO: we need correction if border is smaller than current one
+	 */
+	k = depth - 1;
+	border = path[depth].p_ext->ee_block;
+	path[k].p_idx->ei_block = border;
+
+	while (k--) {
+		/* change all left-side indexes */
+		if (path[k+1].p_idx != EXT_FIRST_INDEX(path[k+1].p_hdr))
+			break;
+		path[k].p_idx->ei_block = border;
+	}
+
+	return;
+}
+
+int ext3_ext_insert_extent(struct ext3_extent_header *eh,
+				struct ext4_ext_path *path,
+				struct ext3_extent *newext)
+{
+
+	struct ext3_extent *ex, *fex;
+	struct ext3_extent *nearex; /* nearest extent */
+	struct ext4_ext_path *npath = NULL;
+	int depth, len, err = 0, next;
+	struct ext3_extent_header *save_eh = eh;
+
+	depth = eh->eh_depth;
+	ex = path[depth].p_ext;
+
+	/* try to insert block into found extent and return */
+	if (ex && ext3_can_extents_be_merged(ex, newext)) {
+		ex->ee_len = ex->ee_len + newext->ee_len;
+		eh = path[depth].p_hdr;
+		nearex = ex;
+		goto merge;
+	}
+
+repeat:
+	/* recalculate depth here */
+	depth=save_eh->eh_depth;
+
+	eh = path[depth].p_hdr;
+	if (eh->eh_entries < eh->eh_max)
+		goto has_space;
+
+	/* probably next leaf has space for us? */
+	fex = EXT_LAST_EXTENT(eh);
+	next = ext3_ext_next_leaf_block(path);
+
+	if (newext->ee_block > fex->ee_block && next != EXT_MAX_BLOCK) {
+
+		npath = ext3_ext_find_extent(save_eh, next, NULL);
+		if (!npath) {
+			return EXT2_ET_BLOCK_ALLOC_FAIL;
+		}
+
+		eh = npath[depth].p_hdr;
+		if (eh->eh_entries < eh->eh_max) {
+			path = npath;
+			goto repeat;
+		}
+	}
+
+	/*
+	 * There is no free space in the found leaf.
+	 * We're gonna add a new leaf in the tree.
+	 */
+	err = ext3_ext_create_new_leaf(save_eh, path, newext);
+	if (err)
+		goto cleanup;
+
+	/* recalculate depth here */
+	depth=save_eh->eh_depth;
+	eh = path[depth].p_hdr;
+
+has_space:
+
+	nearex = path[depth].p_ext;
+
+	if (!nearex) {
+		/* there is no extent in this leaf, create first one */
+		path[depth].p_ext = EXT_FIRST_EXTENT(eh);
+
+	} else if (newext->ee_block > nearex->ee_block) {
+
+		if (nearex != EXT_LAST_EXTENT(eh)) {
+			len = EXT_MAX_EXTENT(eh) - nearex;
+			len = (len - 1) * sizeof(struct ext3_extent);
+			len = len < 0 ? 0 : len;
+			memmove(nearex + 2, nearex + 1, len);
+		}
+		path[depth].p_ext = nearex + 1;
+	} else {
+		len = (EXT_MAX_EXTENT(eh) - nearex)*sizeof(struct ext3_extent);
+		len = len < 0 ? 0 : len;
+		memmove(nearex + 1, nearex, len);
+		path[depth].p_ext = nearex;
+	}
+
+	eh->eh_entries = eh->eh_entries+1;
+	nearex = path[depth].p_ext;
+	nearex->ee_block = newext->ee_block;
+	nearex->ee_start = newext->ee_start;
+	nearex->ee_start_hi = newext->ee_start_hi;
+	nearex->ee_len = newext->ee_len;
+
+merge:
+	/* try to merge extents to the right */
+	while (nearex < EXT_LAST_EXTENT(eh)) {
+		if (!ext3_can_extents_be_merged(nearex, nearex + 1))
+			break;
+		/* merge with next extent! */
+		nearex->ee_len = nearex->ee_len + nearex[1].ee_len;
+
+		if (nearex + 1 < EXT_LAST_EXTENT(eh)) {
+			len = (EXT_LAST_EXTENT(eh) - nearex - 1)
+					* sizeof(struct ext3_extent);
+			memmove(nearex + 1, nearex + 2, len);
+		}
+		eh->eh_entries = eh->eh_entries-1;
+	}
+
+	/* try to merge extents to the left */
+
+	/* time to correct all indexes above */
+	ext3_ext_correct_indexes(save_eh, path);
+
+cleanup:
+	if (npath) {
+		free(npath);
+	}
+
+	return err;
+}
+

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@@ -0,0 +1,10 @@
+
+struct ext4_ext_path * ext3_ext_find_extent(struct ext3_extent_header *,
+						blk_t , struct ext4_ext_path *);
+struct blk_cache * get_block(ext4_fsblk_t);
+int ext3_ext_space_root(void);
+ext4_fsblk_t ext_pblock(struct ext3_extent *);
+ext4_fsblk_t idx_pblock(struct ext3_extent_idx *);
+void ext3_ext_store_pblock(struct ext3_extent *, ext4_fsblk_t );
+int ext3_ext_insert_extent(struct ext3_extent_header *,
+				struct ext4_ext_path *, struct ext3_extent *);

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+
+#include "ext2fs/ext2_fs.h"
+#include "ext2fs/ext2fs.h"
+#include "blkid/list.h"
+
+typedef unsigned long long ext4_fsblk_t;
+
+extern ext2_filsys current_fs;
+
+#define EXT4_EXT_MAGIC		0xf30a
+#define EXT2_SET_INCOMPAT_FEATURE(sb,mask) \
+	( EXT2_SB(sb)->s_feature_incompat |= (mask) )
+
+
+struct list_blocks_struct {
+	blk_t		first_block, last_block;
+	e2_blkcnt_t	first_bcnt, last_bcnt;
+};
+
+struct  blk_stat {
+	struct list_head  head;
+	ext4_fsblk_t pblock;
+	int dirty;
+};
+
+struct blk_cache {
+	struct list_head  head;
+	ext4_fsblk_t pblock;
+	void * block_mem_addr;
+};