1)In migration, get rid of page and buffer of src inode(fs_flushinval_pages). 2)fix...

[fs/lustre-release.git] / lustre / kernel_patches / patches / ext3-extents-2.4.20.patch

Index: linux-2.4.20/fs/ext3/extents.c
===================================================================
--- linux-2.4.20.orig/fs/ext3/extents.c 2003-01-30 13:24:37.000000000 +0300
+++ linux-2.4.20/fs/ext3/extents.c      2004-01-24 14:19:29.000000000 +0300
@@ -0,0 +1,2224 @@
+/*
+ * Copyright (C) 2003 Alex Tomas <alex@clusterfs.com>
+ *
+ * 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-
+ */
+
+/*
+ * Extents support for EXT3
+ *
+ * TODO:
+ *   - ext3_ext_walk_space() sould not use ext3_ext_find_extent()
+ *   - ext3_ext_calc_credits() could take 'mergable' into account
+ *   - ext3*_error() should be used in some situations
+ *   - find_goal() [to be tested and improved]
+ *   - smart tree reduction
+ *   - arch-independence
+ *     common on-disk format for big/little-endian arch
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/time.h>
+#include <linux/ext3_jbd.h>
+#include <linux/jbd.h>
+#include <linux/smp_lock.h>
+#include <linux/highuid.h>
+#include <linux/pagemap.h>
+#include <linux/quotaops.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/locks.h>
+#include <linux/ext3_extents.h>
+#include <asm/uaccess.h>
+
+static handle_t *ext3_ext_journal_restart(handle_t *handle, int needed)
+{
+       int err;
+
+       if (handle->h_buffer_credits > needed)
+               return handle;
+       if (!ext3_journal_extend(handle, needed))
+               return handle;
+       err = ext3_journal_restart(handle, needed);
+       
+       return handle;
+}
+
+static int inline
+ext3_ext_get_access_for_root(handle_t *h, struct ext3_extents_tree *tree)
+{
+       if (tree->get_write_access)
+               return tree->get_write_access(h,tree->buffer);
+       else
+               return 0;
+}
+
+static int inline
+ext3_ext_mark_root_dirty(handle_t *h, struct ext3_extents_tree *tree)
+{
+       if (tree->mark_buffer_dirty)
+               return tree->mark_buffer_dirty(h,tree->buffer);
+       else
+               return 0;
+}
+
+/*
+ * could return:
+ *  - EROFS
+ *  - ENOMEM
+ */
+static int ext3_ext_get_access(handle_t *handle,
+                               struct ext3_extents_tree *tree,
+                               struct ext3_ext_path *path)
+{
+       if (path->p_bh) {
+               /* path points to block */
+               return ext3_journal_get_write_access(handle, path->p_bh);
+       }
+
+       /* path points to leaf/index in inode body */
+       return ext3_ext_get_access_for_root(handle, tree);
+}
+
+/*
+ * could return:
+ *  - EROFS
+ *  - ENOMEM
+ *  - EIO
+ */
+static int ext3_ext_dirty(handle_t *handle, struct ext3_extents_tree *tree,
+                               struct ext3_ext_path *path)
+{
+       if (path->p_bh) {
+               /* path points to block */
+               return ext3_journal_dirty_metadata(handle, path->p_bh);
+       }
+
+       /* path points to leaf/index in inode body */
+       return ext3_ext_mark_root_dirty(handle, tree);
+}
+
+static int inline
+ext3_ext_new_block(handle_t *handle, struct ext3_extents_tree *tree,
+                       struct ext3_ext_path *path, struct ext3_extent *ex,
+                       int *err)
+{
+       int goal, depth, newblock;
+       struct inode *inode;
+
+       EXT_ASSERT(tree);
+       if (tree->new_block)
+               return tree->new_block(handle, tree, path, ex, err);
+
+       inode = tree->inode;
+       depth = EXT_DEPTH(tree);
+       if (path && depth > 0) {
+               goal = path[depth-1].p_block;
+       } else {
+               struct ext3_inode_info *ei = EXT3_I(inode);
+               unsigned long bg_start;
+               unsigned long colour;
+
+               bg_start = (ei->i_block_group *
+                               EXT3_BLOCKS_PER_GROUP(inode->i_sb)) +
+                       le32_to_cpu(EXT3_SB(inode->i_sb)->s_es->s_first_data_block);
+               colour = (current->pid % 16) *
+                       (EXT3_BLOCKS_PER_GROUP(inode->i_sb) / 16);
+               goal = bg_start + colour;
+       }
+
+       newblock = ext3_new_block(handle, inode, goal, 0, 0, err);
+       return newblock;
+}
+
+static inline int ext3_ext_space_block(struct ext3_extents_tree *tree)
+{
+       int size;
+
+       size = (tree->inode->i_sb->s_blocksize -
+                       sizeof(struct ext3_extent_header))
+                               / sizeof(struct ext3_extent);
+#ifdef AGRESSIVE_TEST
+       size = 6;
+#endif
+       return size;
+}
+
+static inline int ext3_ext_space_block_idx(struct ext3_extents_tree *tree)
+{
+       int size;
+
+       size = (tree->inode->i_sb->s_blocksize -
+                       sizeof(struct ext3_extent_header))
+                               / sizeof(struct ext3_extent_idx);
+#ifdef AGRESSIVE_TEST
+       size = 5;
+#endif
+       return size;
+}
+
+static inline int ext3_ext_space_root(struct ext3_extents_tree *tree)
+{
+       int size;
+
+       size = (tree->buffer_len - sizeof(struct ext3_extent_header))
+                       / sizeof(struct ext3_extent);
+#ifdef AGRESSIVE_TEST
+       size = 3;
+#endif
+       return size;
+}
+
+static inline int ext3_ext_space_root_idx(struct ext3_extents_tree *tree)
+{
+       int size;
+
+       size = (tree->buffer_len -
+                       sizeof(struct ext3_extent_header))
+                       / sizeof(struct ext3_extent_idx);
+#ifdef AGRESSIVE_TEST
+       size = 4;
+#endif
+       return size;
+}
+
+static void ext3_ext_show_path(struct ext3_extents_tree *tree,
+                               struct ext3_ext_path *path)
+{
+#ifdef EXT_DEBUG
+       int k, l = path->p_depth;
+
+       ext_debug(tree, "path:");
+       for (k = 0; k <= l; k++, path++) {
+               if (path->p_idx) {
+                       ext_debug(tree, "  %d->%d", path->p_idx->e_block,
+                                       path->p_idx->e_leaf);
+               } else if (path->p_ext) {
+                       ext_debug(tree, "  %d:%d:%d",
+                                       path->p_ext->e_block,
+                                       path->p_ext->e_num,
+                                       path->p_ext->e_start);
+               } else
+                       ext_debug(tree, "  []");
+       }
+       ext_debug(tree, "\n");
+#endif
+}
+
+static void ext3_ext_show_leaf(struct ext3_extents_tree *tree,
+                               struct ext3_ext_path *path)
+{
+#ifdef EXT_DEBUG
+       int depth = EXT_DEPTH(tree);
+       struct ext3_extent_header *eh;
+       struct ext3_extent *ex;
+       int i;
+
+       if (!path)
+               return;
+
+       eh = path[depth].p_hdr;
+       ex = EXT_FIRST_EXTENT(eh);
+
+       for (i = 0; i < eh->e_num; i++, ex++) {
+               ext_debug(tree, "%d:%d:%d ",
+                               ex->e_block, ex->e_num, ex->e_start);
+       }
+       ext_debug(tree, "\n");
+#endif
+}
+
+static void ext3_ext_drop_refs(struct ext3_ext_path *path)
+{
+       int depth = path->p_depth;
+       int i;
+
+       for (i = 0; i <= depth; i++, path++)
+               if (path->p_bh) {
+                       brelse(path->p_bh);
+                       path->p_bh = NULL;
+               }
+}
+
+/*
+ * binary search for closest index by given block
+ */
+static inline void
+ext3_ext_binsearch_idx(struct ext3_extents_tree *tree,
+                       struct ext3_ext_path *path, int block)
+{
+       struct ext3_extent_header *eh = path->p_hdr;
+       struct ext3_extent_idx *ix;
+       int l = 0, k, r;
+
+       EXT_ASSERT(eh->e_num <= eh->e_max);
+       EXT_ASSERT(eh->e_num > 0);
+
+       ext_debug(tree, "binsearch for %d(idx):  ", block);
+
+       path->p_idx = ix = EXT_FIRST_INDEX(eh);
+
+       r = k = eh->e_num;
+       while (k > 1) {
+               k = (r - l) / 2;
+               if (block < ix[l + k].e_block)
+                       r -= k;
+               else
+                       l += k;
+               ext_debug(tree, "%d:%d:%d ", k, l, r);
+       }
+
+       ix += l;
+       path->p_idx = ix;
+       ext_debug(tree, "  -> %d->%d ", path->p_idx->e_block, path->p_idx->e_leaf);
+
+       while (l++ < r) {
+               if (block < ix->e_block) 
+                       break;
+               path->p_idx = ix++;
+       }
+       ext_debug(tree, "  -> %d->%d\n", path->p_idx->e_block,
+                       path->p_idx->e_leaf);
+
+#ifdef CHECK_BINSEARCH 
+       {
+               struct ext3_extent_idx *chix;
+
+               chix = ix = EXT_FIRST_INDEX(eh);
+               for (k = 0; k < eh->e_num; k++, ix++) {
+                       EXT_ASSERT(k == 0 || ix->e_block > ix[-1].e_block);
+                       if (block < ix->e_block) 
+                               break;
+                       chix = ix;
+               }
+               EXT_ASSERT(chix == path->p_idx);
+       }
+#endif
+
+}
+
+/*
+ * binary search for closest extent by given block
+ */
+static inline void
+ext3_ext_binsearch(struct ext3_extents_tree *tree,
+                       struct ext3_ext_path *path, int block)
+{
+       struct ext3_extent_header *eh = path->p_hdr;
+       struct ext3_extent *ex;
+       int l = 0, k, r;
+
+       EXT_ASSERT(eh->e_num <= eh->e_max);
+
+       if (eh->e_num == 0) {
+               /*
+                * this leaf is empty yet:
+                *  we get such a leaf in split/add case
+                */
+               return;
+       }
+       
+       ext_debug(tree, "binsearch for %d:  ", block);
+
+       path->p_ext = ex = EXT_FIRST_EXTENT(eh);
+
+       r = k = eh->e_num;
+       while (k > 1) {
+               k = (r - l) / 2;
+               if (block < ex[l + k].e_block)
+                       r -= k;
+               else
+                       l += k;
+               ext_debug(tree, "%d:%d:%d ", k, l, r);
+       }
+
+       ex += l;
+       path->p_ext = ex;
+       ext_debug(tree, "  -> %d:%d:%d ", path->p_ext->e_block,
+                       path->p_ext->e_start, path->p_ext->e_num);
+
+       while (l++ < r) {
+               if (block < ex->e_block) 
+                       break;
+               path->p_ext = ex++;
+       }
+       ext_debug(tree, "  -> %d:%d:%d\n", path->p_ext->e_block,
+                       path->p_ext->e_start, path->p_ext->e_num);
+
+#ifdef CHECK_BINSEARCH 
+       {
+               struct ext3_extent *chex;
+
+               chex = ex = EXT_FIRST_EXTENT(eh);
+               for (k = 0; k < eh->e_num; k++, ex++) {
+                       EXT_ASSERT(k == 0 || ex->e_block > ex[-1].e_block);
+                       if (block < ex->e_block) 
+                               break;
+                       chex = ex;
+               }
+               EXT_ASSERT(chex == path->p_ext);
+       }
+#endif
+
+}
+
+int ext3_extent_tree_init(handle_t *handle, struct ext3_extents_tree *tree)
+{
+       struct ext3_extent_header *eh;
+
+       BUG_ON(tree->buffer_len == 0);
+       ext3_ext_get_access_for_root(handle, tree);
+       eh = EXT_ROOT_HDR(tree);
+       eh->e_depth = 0;
+       eh->e_num = 0;
+       eh->e_max = ext3_ext_space_root(tree);
+       ext3_ext_mark_root_dirty(handle, tree);
+       return 0;
+}
+
+struct ext3_ext_path *
+ext3_ext_find_extent(struct ext3_extents_tree *tree, int block,
+                       struct ext3_ext_path *path)
+{
+       struct ext3_extent_header *eh;
+       struct buffer_head *bh;
+       int depth, i, ppos = 0;
+
+       EXT_ASSERT(tree);
+       EXT_ASSERT(tree->inode);
+       EXT_ASSERT(tree->root);
+
+       eh = EXT_ROOT_HDR(tree);
+       i = depth = EXT_DEPTH(tree);
+       EXT_ASSERT(eh->e_max);
+       EXT_ASSERT(i == 0 || eh->e_num > 0);
+       
+       /* account possible depth increase */
+       if (!path) {
+               path = kmalloc(sizeof(struct ext3_ext_path) * (depth + 2),
+                               GFP_NOFS);
+               if (!path)
+                       return ERR_PTR(-ENOMEM);
+       }
+       memset(path, 0, sizeof(struct ext3_ext_path) * (depth + 1));
+       path[0].p_hdr = eh;
+
+       /* walk through the tree */
+       while (i) {
+               ext_debug(tree, "depth %d: num %d, max %d\n",
+                               ppos, eh->e_num, eh->e_max);
+               ext3_ext_binsearch_idx(tree, path + ppos, block);
+               path[ppos].p_block = path[ppos].p_idx->e_leaf;
+               path[ppos].p_depth = i;
+               path[ppos].p_ext = NULL;
+
+               bh = sb_bread(tree->inode->i_sb, path[ppos].p_block);
+               if (!bh) {
+                       ext3_ext_drop_refs(path);
+                       kfree(path);
+                       return ERR_PTR(-EIO);
+               }
+               eh = EXT_BLOCK_HDR(bh);
+               ppos++;
+               EXT_ASSERT(ppos <= depth);
+               path[ppos].p_bh = bh;
+               path[ppos].p_hdr = eh;
+               i--;
+       }
+
+       path[ppos].p_depth = i;
+       path[ppos].p_hdr = eh;
+       path[ppos].p_ext = NULL;
+
+       /* find extent */
+       ext3_ext_binsearch(tree, path + ppos, block);
+
+       ext3_ext_show_path(tree, path);
+
+       return path;
+}
+
+/*
+ * insert new index [logical;ptr] into the block at cupr
+ * it check where to insert: before curp or after curp
+ */
+static int ext3_ext_insert_index(handle_t *handle,
+                               struct ext3_extents_tree *tree,
+                               struct ext3_ext_path *curp,
+                               int logical, int ptr)
+{
+       struct ext3_extent_idx *ix;
+       int len, err;
+
+       if ((err = ext3_ext_get_access(handle, tree, curp)))
+               return err;
+
+       EXT_ASSERT(logical != curp->p_idx->e_block);
+       len = EXT_MAX_INDEX(curp->p_hdr) - curp->p_idx;
+       if (logical > curp->p_idx->e_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;
+                       ext_debug(tree, "insert new index %d after: %d. "
+                                       "move %d from 0x%p to 0x%p\n",
+                                       logical, ptr, len,
+                                       (curp->p_idx + 1), (curp->p_idx + 2));
+                       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;
+               ext_debug(tree, "insert new index %d before: %d. "
+                               "move %d from 0x%p to 0x%p\n",
+                               logical, ptr, len,
+                               curp->p_idx, (curp->p_idx + 1));
+               memmove(curp->p_idx + 1, curp->p_idx, len);
+               ix = curp->p_idx;
+       }
+
+       ix->e_block = logical;
+       ix->e_leaf = ptr;
+       curp->p_hdr->e_num++;
+
+       err = ext3_ext_dirty(handle, tree, curp);
+       ext3_std_error(tree->inode->i_sb, err);
+
+       return err;
+}
+
+/*
+ * routine 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 extens and index entries (right to the split point)
+ *    into the newly allocated blocks
+ *  - initialize subtree
+ */
+static int ext3_ext_split(handle_t *handle, struct ext3_extents_tree *tree,
+                               struct ext3_ext_path *path,
+                               struct ext3_extent *newext, int at)
+{
+       struct buffer_head *bh = NULL;
+       int depth = EXT_DEPTH(tree);
+       struct ext3_extent_header *neh;
+       struct ext3_extent_idx *fidx;
+       struct ext3_extent *ex;
+       int i = at, k, m, a;
+       unsigned long newblock, oldblock, border;
+       int *ablocks = NULL; /* array of allocated blocks */
+       int err = 0;
+
+       /* make decision: where to split? */
+       /* FIXME: now desicion is simplest: at current extent */
+
+       /* if current leaf will be splitted, 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].e_block;
+               ext_debug(tree, "leaf will be splitted."
+                               " next leaf starts at %d\n",
+                               (int)border);
+       } else {
+               border = newext->e_block;
+               ext_debug(tree, "leaf will be added."
+                               " next leaf starts at %d\n",
+                               (int)border);
+       }
+
+       /* 
+        * if error occurs, then we break processing
+        * and turn filesystem read-only. so, 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 = kmalloc(sizeof(unsigned long) * depth, GFP_NOFS);
+       if (!ablocks)
+               return -ENOMEM;
+       memset(ablocks, 0, sizeof(unsigned long) * depth);
+
+       /* allocate all needed blocks */
+       ext_debug(tree, "allocate %d blocks for indexes/leaf\n", depth - at);
+       for (a = 0; a < depth - at; a++) {
+               newblock = ext3_ext_new_block(handle, tree, path, newext, &err);
+               if (newblock == 0)
+                       goto cleanup;
+               ablocks[a] = newblock;
+       }
+
+       /* initialize new leaf */
+       newblock = ablocks[--a];
+       EXT_ASSERT(newblock);
+       bh = sb_getblk(tree->inode->i_sb, newblock);
+       if (!bh) {
+               err = -EIO;
+               goto cleanup;
+       }
+       lock_buffer(bh);
+
+       if ((err = ext3_journal_get_create_access(handle, bh)))
+               goto cleanup;
+
+       neh = EXT_BLOCK_HDR(bh);
+       neh->e_num = 0;
+       neh->e_max = ext3_ext_space_block(tree);
+       ex = EXT_FIRST_EXTENT(neh);
+
+       /* move remain of path[depth] to the new leaf */
+       EXT_ASSERT(path[depth].p_hdr->e_num == path[depth].p_hdr->e_max);
+       /* 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)) {
+               ext_debug(tree, "move %d:%d:%d in new leaf\n",
+                               path[depth].p_ext->e_block,
+                               path[depth].p_ext->e_start,
+                               path[depth].p_ext->e_num);
+               memmove(ex++, path[depth].p_ext++,
+                               sizeof(struct ext3_extent));
+               neh->e_num++;
+               m++;
+       }
+       mark_buffer_uptodate(bh, 1);
+       unlock_buffer(bh);
+
+       if ((err = ext3_journal_dirty_metadata(handle, bh)))
+               goto cleanup;   
+       brelse(bh);
+       bh = NULL;
+
+       /* correct old leaf */
+       if (m) {
+               if ((err = ext3_ext_get_access(handle, tree, path)))
+                       goto cleanup;
+               path[depth].p_hdr->e_num -= m;
+               if ((err = ext3_ext_dirty(handle, tree, path)))
+                       goto cleanup;
+               
+       }
+
+       /* create intermediate indexes */
+       k = depth - at - 1;
+       EXT_ASSERT(k >= 0);
+       if (k)
+               ext_debug(tree, "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 = sb_getblk(tree->inode->i_sb, newblock);
+               if (!bh) {
+                       err = -EIO;
+                       goto cleanup;
+               }
+               lock_buffer(bh);
+
+               if ((err = ext3_journal_get_create_access(handle, bh)))
+                       goto cleanup;
+
+               neh = EXT_BLOCK_HDR(bh);
+               neh->e_num = 1;
+               neh->e_max = ext3_ext_space_block_idx(tree);
+               fidx = EXT_FIRST_INDEX(neh);
+               fidx->e_block = border;
+               fidx->e_leaf = oldblock;
+
+               ext_debug(tree, "int.index at %d (block %u): %d -> %d\n",
+                               i, (unsigned) newblock,
+                               (int) border,
+                               (int) oldblock);
+               /* copy indexes */
+               m = 0;
+               path[i].p_idx++;
+               ext_debug(tree, "cur 0x%p, last 0x%p\n", path[i].p_idx,
+                               EXT_MAX_INDEX(path[i].p_hdr));
+               EXT_ASSERT(EXT_MAX_INDEX(path[i].p_hdr) ==
+                               EXT_LAST_INDEX(path[i].p_hdr));
+               while (path[i].p_idx <=
+                               EXT_MAX_INDEX(path[i].p_hdr)) {
+                       ext_debug(tree, "%d: move %d:%d in new index\n",
+                                       i, path[i].p_idx->e_block,
+                                       path[i].p_idx->e_leaf);
+                       memmove(++fidx, path[i].p_idx++,
+                                       sizeof(struct ext3_extent_idx));
+                       neh->e_num++;
+                       m++;
+               }
+
+               mark_buffer_uptodate(bh, 1);
+               unlock_buffer(bh);
+
+               if ((err = ext3_journal_dirty_metadata(handle, bh)))
+                       goto cleanup;
+               brelse(bh);
+               bh = NULL;
+
+               /* correct old index */
+               if (m) {
+                       err = ext3_ext_get_access(handle, tree, path + i);
+                       if (err)
+                               goto cleanup;
+                       path[i].p_hdr->e_num -= m;
+                       err = ext3_ext_dirty(handle, tree, path + i);
+                       if (err)
+                               goto cleanup;
+               }
+
+               i--;
+       }
+
+       /* insert new index */
+       if (!err)
+               err = ext3_ext_insert_index(handle, tree, path + at,
+                                               border, newblock);
+
+cleanup:
+       if (bh) {
+               if (buffer_locked(bh))
+                       unlock_buffer(bh);
+               brelse(bh);
+       }
+
+       if (err) {
+               /* free all allocated blocks in error case */
+               for (i = 0; i < depth; i++)
+                       if (!ablocks[i])
+                               continue;
+                       ext3_free_blocks(handle, tree->inode, ablocks[i], 1);
+       }
+       kfree(ablocks);
+
+       return err;
+}
+
+/*
+ * routine implements tree growing procedure:
+ *  - allocates new block
+ *  - moves top-level data (index block or leaf) into the new block
+ *  - initialize new top-level, creating index that points to the
+ *    just created block
+ */
+static int ext3_ext_grow_indepth(handle_t *handle,
+                                       struct ext3_extents_tree *tree,
+                                       struct ext3_ext_path *path,
+                                       struct ext3_extent *newext)
+{
+       struct buffer_head *bh;
+       struct ext3_ext_path *curp = path;
+       struct ext3_extent_header *neh;
+       struct ext3_extent_idx *fidx;
+       int len, err = 0;
+       unsigned long newblock;
+
+       newblock = ext3_ext_new_block(handle, tree, path, newext, &err);
+       if (newblock == 0)
+               return err;
+
+       bh = sb_getblk(tree->inode->i_sb, newblock);
+       if (!bh) {
+               err = -EIO;
+               ext3_std_error(tree->inode->i_sb, err);
+               return err;
+       }
+       lock_buffer(bh);
+
+       if ((err = ext3_journal_get_create_access(handle, bh))) {
+               unlock_buffer(bh);
+               goto out;       
+       }
+
+       /* move top-level index/leaf into new block */
+       len = sizeof(struct ext3_extent_header) +
+               sizeof(struct ext3_extent) * curp->p_hdr->e_max;
+       EXT_ASSERT(len >= 0 && len < 4096);
+       memmove(bh->b_data, curp->p_hdr, len);
+
+       /* set size of new block */
+       neh = EXT_BLOCK_HDR(bh);
+       neh->e_max = ext3_ext_space_block(tree);
+       mark_buffer_uptodate(bh, 1);
+       unlock_buffer(bh);
+
+       if ((err = ext3_journal_dirty_metadata(handle, bh)))
+               goto out;
+
+       /* create index in new top-level index: num,max,pointer */
+       if ((err = ext3_ext_get_access(handle, tree, curp)))
+               goto out;
+
+       curp->p_hdr->e_max = ext3_ext_space_root_idx(tree);
+       curp->p_hdr->e_num = 1;
+       curp->p_idx = EXT_FIRST_INDEX(curp->p_hdr);
+       curp->p_idx->e_block = EXT_FIRST_EXTENT(path[0].p_hdr)->e_block;
+       curp->p_idx->e_leaf = newblock;
+
+       neh = EXT_ROOT_HDR(tree);
+       fidx = EXT_FIRST_INDEX(neh);
+       ext_debug(tree, "new root: num %d(%d), lblock %d, ptr %d\n",
+                       neh->e_num, neh->e_max, fidx->e_block, fidx->e_leaf); 
+
+       neh->e_depth = path->p_depth + 1;
+       err = ext3_ext_dirty(handle, tree, curp);
+out:
+       brelse(bh);
+
+       return err;
+}
+
+/*
+ * routine finds empty index and adds new leaf. if no free index found
+ * then it requests in-depth growing
+ */
+static int ext3_ext_create_new_leaf(handle_t *handle,
+                                       struct ext3_extents_tree *tree,
+                                       struct ext3_ext_path *path,
+                                       struct ext3_extent *newext)
+{
+       struct ext3_ext_path *curp;
+       int depth, i, err = 0;
+
+repeat:
+       i = depth = EXT_DEPTH(tree);
+       
+       /* 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 contigoues */
+       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(handle, tree, path, newext, i);
+
+               /* refill path */
+               ext3_ext_drop_refs(path);
+               path = ext3_ext_find_extent(tree, newext->e_block, path);
+               if (IS_ERR(path))
+                       err = PTR_ERR(path);
+       } else {
+               /* tree is full, time to grow in depth */
+               err = ext3_ext_grow_indepth(handle, tree, path, newext);
+
+               /* refill path */
+               ext3_ext_drop_refs(path);
+               path = ext3_ext_find_extent(tree, newext->e_block, path);
+               if (IS_ERR(path))
+                       err = PTR_ERR(path);
+       
+               /*
+                * only first (depth 0 -> 1) produces free space
+                * in all other cases we have to split growed tree
+                */
+               depth = EXT_DEPTH(tree);
+               if (path[depth].p_hdr->e_num == path[depth].p_hdr->e_max) {
+                       /* now we need split */
+                       goto repeat;
+               }
+       }
+
+       if (err)
+               return err;
+
+       return 0;
+}
+
+/*
+ * returns allocated block in subsequent extent or 0xffffffff
+ * NOTE: it consider block number from index entry as
+ * allocated block. thus, index entries have to be consistent
+ * with leafs
+ */
+static unsigned long
+ext3_ext_next_allocated_block(struct ext3_ext_path *path)
+{
+       int depth;
+
+       EXT_ASSERT(path != NULL);
+       depth = path->p_depth;
+
+       if (depth == 0 && path->p_ext == NULL)
+               return 0xffffffff;
+
+       /* FIXME: what if index isn't full ?! */
+       while (depth >= 0) {
+               if (depth == path->p_depth) {
+                       /* leaf */
+                       if (path[depth].p_ext !=
+                                       EXT_LAST_EXTENT(path[depth].p_hdr))
+                               return path[depth].p_ext[1].e_block;
+               } else {
+                       /* index */
+                       if (path[depth].p_idx !=
+                                       EXT_LAST_INDEX(path[depth].p_hdr))
+                               return path[depth].p_idx[1].e_block;
+               }
+               depth--;        
+       }
+
+       return 0xffffffff;
+}
+
+/*
+ * returns first allocated block from next leaf or 0xffffffff
+ */
+static unsigned ext3_ext_next_leaf_block(struct ext3_extents_tree *tree,
+                                               struct ext3_ext_path *path)
+{
+       int depth;
+
+       EXT_ASSERT(path != NULL);
+       depth = path->p_depth;
+
+       /* zero-tree has no leaf blocks at all */
+       if (depth == 0)
+               return 0xffffffff;
+
+       /* 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].e_block;
+               depth--;        
+       }
+
+       return 0xffffffff;
+}
+
+/*
+ * 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?
+ */
+int ext3_ext_correct_indexes(handle_t *handle, struct ext3_extents_tree *tree,
+                               struct ext3_ext_path *path)
+{
+       struct ext3_extent_header *eh;
+       int depth = EXT_DEPTH(tree);    
+       struct ext3_extent *ex;
+       unsigned long border;
+       int k, err = 0;
+       
+       eh = path[depth].p_hdr;
+       ex = path[depth].p_ext;
+       EXT_ASSERT(ex);
+       EXT_ASSERT(eh);
+       
+       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 then current one
+        */
+       k = depth - 1;
+       border = path[depth].p_ext->e_block;
+       if ((err = ext3_ext_get_access(handle, tree, path + k)))
+               return err;
+       path[k].p_idx->e_block = border;
+       if ((err = ext3_ext_dirty(handle, tree, path + k)))
+               return err;
+
+       while (k--) {
+               /* change all left-side indexes */
+               if (path[k+1].p_idx != EXT_FIRST_INDEX(path[k+1].p_hdr))
+                       break;
+               if ((err = ext3_ext_get_access(handle, tree, path + k)))
+                       break;
+               path[k].p_idx->e_block = border;
+               if ((err = ext3_ext_dirty(handle, tree, path + k)))
+                       break;
+       }
+
+       return err;
+}
+
+static int inline
+ext3_can_extents_be_merged(struct ext3_extents_tree *tree,
+                               struct ext3_extent *ex1,
+                               struct ext3_extent *ex2)
+{
+       if (ex1->e_block + ex1->e_num != ex2->e_block)
+               return 0;
+
+#ifdef AGRESSIVE_TEST
+       if (ex1->e_num >= 4)
+               return 0;
+#endif
+
+       if (!tree->mergable)
+               return 1;
+
+       return tree->mergable(ex1, ex2);
+}
+
+/*
+ * this routine tries to merge requsted extent into the existing
+ * extent or inserts requested extent as new one into the tree,
+ * creating new leaf in no-space case
+ */
+int ext3_ext_insert_extent(handle_t *handle, struct ext3_extents_tree *tree,
+                               struct ext3_ext_path *path,
+                               struct ext3_extent *newext)
+{
+       int depth, len;
+       struct ext3_extent_header * eh;
+       struct ext3_extent *ex;
+       struct ext3_extent *nearex; /* nearest extent */
+       struct ext3_ext_path *npath = NULL;
+       int err;
+
+       depth = EXT_DEPTH(tree);
+       ex = path[depth].p_ext;
+
+       /* try to insert block into found extent and return */
+       if (ex && ext3_can_extents_be_merged(tree, ex, newext)) {
+               ext_debug(tree, "append %d block to %d:%d (from %d)\n",
+                               newext->e_num, ex->e_block, ex->e_num,
+                               ex->e_start);
+               if ((err = ext3_ext_get_access(handle, tree, path + depth)))
+                       return err;
+               ex->e_num += newext->e_num;
+               err = ext3_ext_dirty(handle, tree, path + depth);
+               return err;
+       }
+
+repeat:
+       depth = EXT_DEPTH(tree);
+       eh = path[depth].p_hdr;
+       if (eh->e_num == eh->e_max) {
+               /* probably next leaf has space for us? */
+               int next = ext3_ext_next_leaf_block(tree, path);
+               if (next != 0xffffffff) {
+                       ext_debug(tree, "next leaf block - %d\n", next);
+                       EXT_ASSERT(!npath);
+                       npath = ext3_ext_find_extent(tree, next, NULL);
+                       if (IS_ERR(npath))
+                               return PTR_ERR(npath);
+                       EXT_ASSERT(npath->p_depth == path->p_depth);
+                       eh = npath[depth].p_hdr;
+                       if (eh->e_num < eh->e_max) {
+                               ext_debug(tree, "next leaf isnt full(%d)\n",
+                                               eh->e_num);
+                               path = npath;
+                               goto repeat;
+                       }
+                       ext_debug(tree, "next leaf hasno free space(%d,%d)\n",
+                                       eh->e_num, eh->e_max);
+               }
+               /*
+                * there is no free space in found leaf
+                * we're gonna add new leaf in the tree
+                */
+               err = ext3_ext_create_new_leaf(handle, tree, path, newext);
+               if (err)
+                       goto cleanup;
+               goto repeat;
+       }
+
+       nearex = path[depth].p_ext;
+
+       if ((err = ext3_ext_get_access(handle, tree, path + depth)))
+               goto cleanup;
+
+       if (!nearex) {
+               /* there is no extent in this leaf, create first one */
+               ext_debug(tree, "first extent in the leaf: %d:%d:%d\n",
+                               newext->e_block, newext->e_start,
+                               newext->e_num);
+               path[depth].p_ext = EXT_FIRST_EXTENT(eh);
+       } else if (newext->e_block > nearex->e_block) {
+               EXT_ASSERT(newext->e_block != nearex->e_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;
+                       ext_debug(tree, "insert %d:%d:%d after: nearest 0x%p, "
+                                       "move %d from 0x%p to 0x%p\n",
+                                       newext->e_block, newext->e_start,
+                                       newext->e_num,
+                                       nearex, len, nearex + 1, nearex + 2);
+                       memmove(nearex + 2, nearex + 1, len);
+               }
+               path[depth].p_ext = nearex + 1;
+       } else {
+               EXT_ASSERT(newext->e_block != nearex->e_block);
+               len = (EXT_MAX_EXTENT(eh) - nearex) * sizeof(struct ext3_extent);
+               len = len < 0 ? 0 : len;
+               ext_debug(tree, "insert %d:%d:%d before: nearest 0x%p, "
+                               "move %d from 0x%p to 0x%p\n",
+                               newext->e_block, newext->e_start, newext->e_num,
+                               nearex, len, nearex + 1, nearex + 2);
+               
+               memmove(nearex + 1, nearex, len);
+               path[depth].p_ext = nearex;
+       }
+
+       if (!err) {
+               eh->e_num++;
+               nearex = path[depth].p_ext;
+               nearex->e_block = newext->e_block;
+               nearex->e_start = newext->e_start;
+               nearex->e_num = newext->e_num;
+
+               /* time to correct all indexes above */
+               err = ext3_ext_correct_indexes(handle, tree, path);
+       }
+
+       err = ext3_ext_dirty(handle, tree, path + depth);
+
+cleanup:
+       if (npath) {
+               ext3_ext_drop_refs(npath);
+               kfree(npath);
+       }
+               
+       return err;
+}
+
+int ext3_ext_walk_space(struct ext3_extents_tree *tree, unsigned long block,
+                       unsigned long num, ext_prepare_callback func)
+{
+       struct ext3_ext_path *path = NULL;
+       struct ext3_extent *ex, cbex;
+       unsigned long next, start = 0, end = 0;
+       int depth, exists, err = 0;
+
+       EXT_ASSERT(tree);
+       EXT_ASSERT(func);
+       EXT_ASSERT(tree->inode);
+       EXT_ASSERT(tree->root);
+
+       while (num > 0 && block != 0xfffffffff) {
+               /* find extent for this block */
+               path = ext3_ext_find_extent(tree, block, path);
+               if (IS_ERR(path)) {
+                       err = PTR_ERR(path);
+                       break;
+               }
+
+               depth = EXT_DEPTH(tree);
+               ex = path[depth].p_ext;
+               next = ext3_ext_next_allocated_block(path);
+
+               exists = 0;
+               if (!ex) {
+                       /* there is no extent yet, so try to allocate
+                        * all requested space */
+                       start = block;
+                       end = block + num - 1;
+               } else if (ex->e_block > block) {
+                       /* need to allocate space before found extent */
+                       start = block;
+                       end = ex->e_block - 1;
+                       if (block + num - 1 < end)
+                               end = block + num - 1;
+               } else if (block >= ex->e_block + ex->e_num) {
+                       /* need to allocate space after found extent */
+                       start = block;
+                       end = block + num - 1;
+                       if (end >= next)
+                               end = next - 1;
+               } else if (block >= ex->e_block) {
+                       /* 
+                        * some part of requested space is covered
+                        * by found extent
+                        */
+                       start = block;
+                       end = ex->e_block + ex->e_num - 1;
+                       if (block + num - 1 < end)
+                               end = block + num - 1;
+                       exists = 1;
+               } else {
+                       BUG();
+               }
+
+               if (!exists) {
+                       cbex.e_block = start;
+                       cbex.e_num = end - start + 1;
+                       cbex.e_start = 0;
+               } else
+                       cbex = *ex;
+
+               err = func(tree, path, &cbex, exists);
+               if (err < 0)
+                       break;
+
+               if (err == EXT_BREAK) {
+                       err = 0;
+                       break;
+               }
+
+               if (EXT_DEPTH(tree) != depth) {
+                       /* depth was changed. we have to realloc path */
+                       ext3_ext_drop_refs(path);
+                       kfree(path);
+                       path = NULL;
+               }
+
+               block += cbex.e_num;
+               num -= cbex.e_num;
+       }
+
+       if (path) {
+               ext3_ext_drop_refs(path);
+               kfree(path);
+       }
+
+       return err;
+}
+
+static inline void
+ext3_ext_invalidate_cache(struct ext3_extents_tree *tree)
+{
+       if (tree->cex)
+               tree->cex->e_num = 0;
+}
+
+static inline void
+ext3_ext_put_in_cache(struct ext3_extents_tree *tree, struct ext3_extent *ex)
+{
+       if (tree->cex) {
+               EXT_ASSERT(ex);
+               EXT_ASSERT(ex->e_num);
+               tree->cex->e_block = ex->e_block;
+               tree->cex->e_start = ex->e_start;
+               tree->cex->e_num = ex->e_num;
+       }
+}
+
+/*
+ * this routine calculate boundaries of the gap requested block fits into
+ * and cache this gap
+ */
+static inline void
+ext3_ext_put_gap_in_cache(struct ext3_extents_tree *tree,
+                               struct ext3_ext_path *path,
+                               unsigned long block)
+{
+       int depth = EXT_DEPTH(tree);
+       struct ext3_extent *ex, gex;
+
+       ex = path[depth].p_ext;
+       if (ex == NULL) {
+               /* there is no extent yet, so gap is [0;-] */
+               gex.e_block = 0;
+               gex.e_num = 0xffffffff;
+               ext_debug(tree, "cache gap(whole file):");
+       } else if (block < ex->e_block) {
+               gex.e_block = block;
+               gex.e_num = ex->e_block - block;
+               ext_debug(tree, "cache gap(before): %lu [%lu:%lu]",
+                               (unsigned long) block,
+                               (unsigned long) ex->e_block,
+                               (unsigned long) ex->e_num);
+       } else if (block >= ex->e_block + ex->e_num) {
+               gex.e_block = ex->e_block + ex->e_num;
+               gex.e_num = ext3_ext_next_allocated_block(path);
+               ext_debug(tree, "cache gap(after): [%lu:%lu] %lu",
+                               (unsigned long) ex->e_block,
+                               (unsigned long) ex->e_num,
+                               (unsigned long) block);
+               EXT_ASSERT(gex.e_num > gex.e_block);
+               gex.e_num = gex.e_num - gex.e_block;
+       } else {
+               BUG();
+       }
+
+       ext_debug(tree, " -> %lu:%lu\n", (unsigned long) gex.e_block,
+                       (unsigned long) gex.e_num);
+       gex.e_start = 0xffffffff;
+       ext3_ext_put_in_cache(tree, &gex);
+}
+
+static inline int
+ext3_ext_in_cache(struct ext3_extents_tree *tree, unsigned long block,
+                       struct ext3_extent *ex)
+{
+       struct ext3_extent *cex = tree->cex;
+
+       /* is there cache storage at all? */
+       if (!cex)
+               return 0;
+
+       /* has cache valid data? */
+       if (cex->e_num == 0)
+               return 0;
+
+       if (block >= cex->e_block && block < cex->e_block + cex->e_num) {
+               ex->e_block = cex->e_block;
+               ex->e_start = cex->e_start;
+               ex->e_num = cex->e_num;
+               ext_debug(tree, "%lu cached by %lu:%lu:%lu(gap)\n",
+                               (unsigned long) block,
+                               (unsigned long) ex->e_block,
+                               (unsigned long) ex->e_num,
+                               (unsigned long) ex->e_start);
+               return 1;
+       }
+
+       /* not in cache */
+       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 ext3_ext_rm_idx(handle_t *handle, struct ext3_extents_tree *tree,
+                       struct ext3_ext_path *path)
+{
+       struct buffer_head *bh;
+       int err;
+       
+       /* free index block */
+       path--;
+       EXT_ASSERT(path->p_hdr->e_num);
+       if ((err = ext3_ext_get_access(handle, tree, path)))
+               return err;
+       path->p_hdr->e_num--;
+       if ((err = ext3_ext_dirty(handle, tree, path)))
+               return err;
+       ext_debug(tree, "index is empty, remove it, free block %d\n",
+                       path->p_idx->e_leaf);
+       bh = sb_get_hash_table(tree->inode->i_sb, path->p_idx->e_leaf);
+       ext3_forget(handle, 0, tree->inode, bh, path->p_idx->e_leaf);
+       ext3_free_blocks(handle, tree->inode, path->p_idx->e_leaf, 1);
+       return err;
+}
+
+int ext3_ext_calc_credits_for_insert(struct ext3_extents_tree *tree,
+                                       struct ext3_ext_path *path)
+{
+       int depth = EXT_DEPTH(tree);
+       int needed;
+
+       if (path) {
+               /* probably there is space in leaf? */
+               if (path[depth].p_hdr->e_num < path[depth].p_hdr->e_max)
+                       return 1;
+       }
+       
+       /*
+        * the worste case we're expecting is creation of the
+        * new root (growing in depth) with index splitting
+        * for splitting we have to consider depth + 1 because
+        * previous growing could increase it
+        */
+       depth = depth + 1;
+
+       /* 
+        * growing in depth:
+        * block allocation + new root + old root
+        */
+       needed = EXT3_ALLOC_NEEDED + 2;
+
+       /* index split. we may need:
+        *   allocate intermediate indexes and new leaf
+        *   change two blocks at each level, but root
+        *   modify root block (inode)
+        */
+       needed += (depth * EXT3_ALLOC_NEEDED) + (2 * depth) + 1;
+
+       return needed;
+}
+
+static int
+ext3_ext_split_for_rm(handle_t *handle, struct ext3_extents_tree *tree,
+                       struct ext3_ext_path *path, unsigned long start,
+                       unsigned long end)
+{
+       struct ext3_extent *ex, tex;
+       struct ext3_ext_path *npath;
+       int depth, creds, err;
+
+       depth = EXT_DEPTH(tree);
+       ex = path[depth].p_ext;
+       EXT_ASSERT(ex);
+       EXT_ASSERT(end < ex->e_block + ex->e_num - 1);
+       EXT_ASSERT(ex->e_block < start);
+
+       /* calculate tail extent */
+       tex.e_block = end + 1;
+       EXT_ASSERT(tex.e_block < ex->e_block + ex->e_num);
+       tex.e_num = ex->e_block + ex->e_num - tex.e_block;
+
+       creds = ext3_ext_calc_credits_for_insert(tree, path);
+       handle = ext3_ext_journal_restart(handle, creds);
+       if (IS_ERR(handle))
+               return PTR_ERR(handle);
+       
+       /* calculate head extent. use primary extent */
+       err = ext3_ext_get_access(handle, tree, path + depth);
+       if (err)
+               return err;
+       ex->e_num = start - ex->e_block;
+       err = ext3_ext_dirty(handle, tree, path + depth);
+       if (err)
+               return err;
+
+       /* FIXME: some callback to free underlying resource
+        * and correct e_start? */
+       ext_debug(tree, "split extent: head %u:%u, tail %u:%u\n",
+                       ex->e_block, ex->e_num, tex.e_block, tex.e_num);
+
+       npath = ext3_ext_find_extent(tree, ex->e_block, NULL);
+       if (IS_ERR(npath))
+               return PTR_ERR(npath);
+       depth = EXT_DEPTH(tree);
+       EXT_ASSERT(npath[depth].p_ext->e_block == ex->e_block);
+       EXT_ASSERT(npath[depth].p_ext->e_num == ex->e_num);
+
+       err = ext3_ext_insert_extent(handle, tree, npath, &tex);
+       ext3_ext_drop_refs(npath);
+       kfree(npath);
+
+       return err;
+                       
+}
+
+static int
+ext3_ext_rm_leaf(handle_t *handle, struct ext3_extents_tree *tree,
+                       struct ext3_ext_path *path, unsigned long start,
+                       unsigned long end)
+{
+       struct ext3_extent *ex, *fu = NULL, *lu, *le;
+       int err = 0, correct_index = 0;
+       int depth = EXT_DEPTH(tree), credits;
+       struct ext3_extent_header *eh;
+       unsigned a, b, block, num;
+
+       ext_debug(tree, "remove [%lu:%lu] in leaf\n", start, end);
+       if (!path[depth].p_hdr)
+               path[depth].p_hdr = EXT_BLOCK_HDR(path[depth].p_bh);
+       eh = path[depth].p_hdr;
+       EXT_ASSERT(eh);
+       EXT_ASSERT(eh->e_num <= eh->e_max);
+       
+       /* find where to start removing */
+       le = ex = EXT_LAST_EXTENT(eh);
+       while (ex != EXT_FIRST_EXTENT(eh)) {
+               if (ex->e_block <= end)
+                       break;
+               ex--;
+       }
+
+       if (start > ex->e_block && end < ex->e_block + ex->e_num - 1) {
+               /* removal of internal part of the extent requested
+                * tail and head must be placed in different extent
+                * so, we have to insert one more extent */
+               path[depth].p_ext = ex;
+               return ext3_ext_split_for_rm(handle, tree, path, start, end);
+       }
+       
+       lu = ex;
+       while (ex >= EXT_FIRST_EXTENT(eh) &&
+                       ex->e_block + ex->e_num > start) {
+               ext_debug(tree, "remove ext %u:%u\n", ex->e_block, ex->e_num);
+               path[depth].p_ext = ex;
+       
+               a = ex->e_block > start ? ex->e_block : start;
+               b = ex->e_block + ex->e_num - 1 < end ?
+                       ex->e_block + ex->e_num - 1 : end;
+               
+               ext_debug(tree, "  border %u:%u\n", a, b);
+
+               if (a != ex->e_block && b != ex->e_block + ex->e_num - 1) {
+                       block = 0;
+                       num = 0;
+                       BUG();
+               } else if (a != ex->e_block) {
+                       /* remove tail of the extent */
+                       block = ex->e_block;
+                       num = a - block;
+               } else if (b != ex->e_block + ex->e_num - 1) {
+                       /* remove head of the extent */
+                       block = a;
+                       num = b - a;
+               } else {
+                       /* remove whole extent: excelent! */
+                       block = ex->e_block; 
+                       num = 0;
+                       EXT_ASSERT(a == ex->e_block &&
+                                       b == ex->e_block + ex->e_num - 1);
+               }
+
+               if (ex == EXT_FIRST_EXTENT(eh))
+                       correct_index = 1;
+
+               credits = 1;
+               if (correct_index)
+                       credits += (EXT_DEPTH(tree) * EXT3_ALLOC_NEEDED) + 1;
+               if (tree->remove_extent_credits)
+                       credits += tree->remove_extent_credits(tree, ex, a, b);
+               
+               handle = ext3_ext_journal_restart(handle, credits);
+               if (IS_ERR(handle)) {
+                       err = PTR_ERR(handle);
+                       goto out;
+               }
+
+               err = ext3_ext_get_access(handle, tree, path + depth);
+               if (err)
+                       goto out;
+
+               if (tree->remove_extent)
+                       err = tree->remove_extent(tree, ex, a, b);
+               if (err)
+                       goto out;
+
+               if (num == 0) {
+                       /* this extent is removed entirely mark slot unused */
+                       ex->e_start = 0;
+                       eh->e_num--;
+                       fu = ex;
+               }
+
+               ex->e_block = block;
+               ex->e_num = num;
+
+               err = ext3_ext_dirty(handle, tree, path + depth);
+               if (err)
+                       goto out;
+
+               ext_debug(tree, "new extent: %u:%u:%u\n",
+                               ex->e_block, ex->e_num, ex->e_start);
+               ex--;
+       }
+
+       if (fu) {
+               /* reuse unused slots */
+               while (lu < le) {
+                       if (lu->e_start) {
+                               *fu = *lu;
+                               lu->e_start = 0;
+                               fu++;
+                       }
+                       lu++;
+               }
+       }
+
+       if (correct_index && eh->e_num)
+               err = ext3_ext_correct_indexes(handle, tree, path);
+
+       /* if this leaf is free, then we should
+        * remove it from index block above */
+       if (err == 0 && eh->e_num == 0 && path[depth].p_bh != NULL)
+               err = ext3_ext_rm_idx(handle, tree, path + depth);
+
+out:
+       return err;
+}
+
+
+static struct ext3_extent_idx *
+ext3_ext_last_covered(struct ext3_extent_header *hdr, unsigned long block)
+{
+       struct ext3_extent_idx *ix;
+       
+       ix = EXT_LAST_INDEX(hdr);
+       while (ix != EXT_FIRST_INDEX(hdr)) {
+               if (ix->e_block <= block)
+                       break;
+               ix--;
+       }
+       return ix;
+}
+
+/*
+ * returns 1 if current index have to be freed (even partial)
+ */
+static int inline
+ext3_ext_more_to_rm(struct ext3_ext_path *path)
+{
+       EXT_ASSERT(path->p_idx);
+
+       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 (path->p_hdr->e_num == path->p_block)
+               return 0;
+       return 1;
+}
+
+int ext3_ext_remove_space(struct ext3_extents_tree *tree,
+                               unsigned long start, unsigned long end)
+{
+       struct inode *inode = tree->inode;
+       struct super_block *sb = inode->i_sb;
+       int depth = EXT_DEPTH(tree);
+       struct ext3_ext_path *path;
+       handle_t *handle;
+       int i = 0, err = 0;
+
+       ext_debug(tree, "space to be removed: %lu:%lu\n", start, end);
+
+       /* probably first extent we're gonna free will be last in block */
+       handle = ext3_journal_start(inode, depth + 1);
+       if (IS_ERR(handle))
+               return PTR_ERR(handle);
+
+       ext3_ext_invalidate_cache(tree);
+
+       /*
+        * we start scanning from right side freeing all the blocks
+        * after i_size and walking into the deep
+        */
+       path = kmalloc(sizeof(struct ext3_ext_path) * (depth + 1), GFP_KERNEL);
+       if (IS_ERR(path)) {
+               ext3_error(sb, "ext3_ext_remove_space",
+                               "Can't allocate path array");
+               ext3_journal_stop(handle, inode);
+               return -ENOMEM;
+       }
+       memset(path, 0, sizeof(struct ext3_ext_path) * (depth + 1));
+       path[i].p_hdr = EXT_ROOT_HDR(tree);
+       
+       while (i >= 0 && err == 0) {
+               if (i == depth) {
+                       /* this is leaf block */
+                       err = ext3_ext_rm_leaf(handle, tree, path, start, end);
+                       /* root level have p_bh == NULL, brelse() eats this */
+                       brelse(path[i].p_bh);
+                       i--;
+                       continue;
+               }
+               
+               /* this is index block */
+               if (!path[i].p_hdr) {
+                       ext_debug(tree, "initialize header\n");
+                       path[i].p_hdr = EXT_BLOCK_HDR(path[i].p_bh);
+               }
+
+               EXT_ASSERT(path[i].p_hdr->e_num <= path[i].p_hdr->e_max);
+               
+               if (!path[i].p_idx) {
+                       /* this level hasn't touched yet */
+                       path[i].p_idx =
+                               ext3_ext_last_covered(path[i].p_hdr, end);
+                       path[i].p_block = path[i].p_hdr->e_num + 1;
+                       ext_debug(tree, "init index ptr: hdr 0x%p, num %d\n",
+                                       path[i].p_hdr, path[i].p_hdr->e_num);
+               } else {
+                       /* we've already was here, see at next index */
+                       path[i].p_idx--;
+               }
+
+               ext_debug(tree, "level %d - index, first 0x%p, cur 0x%p\n",
+                               i, EXT_FIRST_INDEX(path[i].p_hdr),
+                               path[i].p_idx);
+               if (ext3_ext_more_to_rm(path + i)) {
+                       /* go to the next level */
+                       ext_debug(tree, "move to level %d (block %d)\n",
+                                       i + 1, path[i].p_idx->e_leaf);
+                       memset(path + i + 1, 0, sizeof(*path));
+                       path[i+1].p_bh = sb_bread(sb, path[i].p_idx->e_leaf);
+                       if (!path[i+1].p_bh) {
+                               /* should we reset i_size? */
+                               err = -EIO;
+                               break;
+                       }
+                       /* put actual number of indexes to know is this
+                        * number got changed at the next iteration */
+                       path[i].p_block = path[i].p_hdr->e_num;
+                       i++;
+               } else {
+                       /* we finish processing this index, go up */
+                       if (path[i].p_hdr->e_num == 0 && i > 0) {
+                               /* index is empty, remove it
+                                * handle must be already prepared by the
+                                * truncate_leaf() */
+                               err = ext3_ext_rm_idx(handle, tree, path + i);
+                       }
+                       /* root level have p_bh == NULL, brelse() eats this */
+                       brelse(path[i].p_bh);
+                       i--;
+                       ext_debug(tree, "return to level %d\n", i);
+               }
+       }
+
+       /* TODO: flexible tree reduction should be here */
+       if (path->p_hdr->e_num == 0) {
+               /*
+                * truncate to zero freed all the tree
+                * so, we need to correct e_depth
+                */
+               err = ext3_ext_get_access(handle, tree, path);
+               if (err == 0) {
+                       EXT_ROOT_HDR(tree)->e_depth = 0;
+                       err = ext3_ext_dirty(handle, tree, path);
+               }
+       }
+
+       kfree(path);
+       ext3_journal_stop(handle, inode);
+
+       return err;
+}
+
+/*
+ * called at mount time
+ */
+void ext3_ext_init(struct super_block *sb)
+{
+       /*
+        * possible initialization would be here
+        */
+
+       if (test_opt(sb, EXTENTS))
+               printk("EXT3-fs: file extents enabled\n");
+}
+
+/*
+ * called at umount time
+ */
+void ext3_ext_release(struct super_block *sb)
+{
+}
+
+/************************************************************************
+ * VFS related routines
+ ************************************************************************/
+
+static int ext3_get_inode_write_access(handle_t *handle, void *buffer)
+{
+       /* we use in-core data, not bh */
+       return 0;
+}
+
+static int ext3_mark_buffer_dirty(handle_t *handle, void *buffer)
+{
+       struct inode *inode = buffer;
+       ext3_mark_inode_dirty(handle, inode);
+       return 0;
+}
+
+static int ext3_ext_mergable(struct ext3_extent *ex1,
+                               struct ext3_extent *ex2)
+{
+       if (ex1->e_start + ex1->e_num == ex2->e_start)
+               return 1;
+       return 0;
+}
+
+static int
+ext3_remove_blocks_credits(struct ext3_extents_tree *tree,
+                               struct ext3_extent *ex,
+                               unsigned long from, unsigned long to)
+{
+       int needed;
+       
+       /* at present, extent can't cross block group */;
+       needed = 3; /* bitmap + group desc + sb */
+
+#ifdef CONFIG_QUOTA
+       needed += 2 * EXT3_SINGLEDATA_TRANS_BLOCKS;
+#endif
+       return needed;
+}
+
+static int
+ext3_remove_blocks(struct ext3_extents_tree *tree,
+                               struct ext3_extent *ex,
+                               unsigned long from, unsigned long to)
+{
+       int needed = ext3_remove_blocks_credits(tree, ex, from, to);
+       handle_t *handle = ext3_journal_start(tree->inode, needed);
+
+       if (IS_ERR(handle))
+               return PTR_ERR(handle);
+       if (from >= ex->e_block && to == ex->e_block + ex->e_num - 1) {
+               /* tail removal */
+               unsigned long num, start;
+               num = ex->e_block + ex->e_num - from;
+               start = ex->e_start + ex->e_num - num;
+               ext_debug(tree, "free last %lu blocks starting %lu\n",
+                               num, start);
+               ext3_free_blocks(handle, tree->inode, start, num);
+       } else if (from == ex->e_block && to <= ex->e_block + ex->e_num - 1) {
+               printk("strange request: removal %lu-%lu from %u:%u\n",
+                       from, to, ex->e_block, ex->e_num);
+       } else {
+               printk("strange request: removal(2) %lu-%lu from %u:%u\n",
+                       from, to, ex->e_block, ex->e_num);
+       }
+       ext3_journal_stop(handle, tree->inode);
+       return 0;
+}
+
+static int ext3_ext_find_goal(struct inode *inode,
+                               struct ext3_ext_path *path)
+{
+       struct ext3_inode_info *ei = EXT3_I(inode);
+       unsigned long bg_start;
+       unsigned long colour;
+       int depth;
+       
+       if (path) {
+               depth = path->p_depth;
+               /* try to find previous block */
+               if (path[depth].p_ext)
+                       return path[depth].p_ext->e_start +
+                               path[depth].p_ext->e_num - 1;
+               
+               /* it looks index is empty
+                * try to find starting from index itself */
+               if (path[depth].p_bh)
+                       return path[depth].p_bh->b_blocknr;
+       }
+
+       /* OK. use inode's group */
+       bg_start = (ei->i_block_group * EXT3_BLOCKS_PER_GROUP(inode->i_sb)) +
+               le32_to_cpu(EXT3_SB(inode->i_sb)->s_es->s_first_data_block);
+       colour = (current->pid % 16) *
+                       (EXT3_BLOCKS_PER_GROUP(inode->i_sb) / 16);
+       return bg_start + colour;
+}
+
+static int ext3_new_block_cb(handle_t *handle, struct ext3_extents_tree *tree,
+                               struct ext3_ext_path *path,
+                               struct ext3_extent *ex, int *err)
+{
+       struct inode *inode = tree->inode;
+       int newblock, goal;
+       
+       EXT_ASSERT(path);
+       EXT_ASSERT(ex);
+       EXT_ASSERT(ex->e_start);
+       EXT_ASSERT(ex->e_num);
+       
+       /* reuse block from the extent to order data/metadata */
+       newblock = ex->e_start++;
+       ex->e_num--;
+       if (ex->e_num == 0) {
+               ex->e_num = 1;
+               /* allocate new block for the extent */
+               goal = ext3_ext_find_goal(inode, path);
+               ex->e_start = ext3_new_block(handle, inode, goal, 0, 0, err);
+               if (ex->e_start == 0) {
+                       /* error occured: restore old extent */
+                       ex->e_start = newblock;
+                       return 0;
+               }
+       }
+       return newblock;
+}
+
+static void ext3_init_tree_desc(struct ext3_extents_tree *tree,
+                               struct inode *inode)
+{
+       tree->inode = inode;
+       tree->root = (void *) EXT3_I(inode)->i_data;
+       tree->get_write_access = ext3_get_inode_write_access;
+       tree->mark_buffer_dirty = ext3_mark_buffer_dirty;
+       tree->mergable = ext3_ext_mergable;
+       tree->new_block = ext3_new_block_cb;
+       tree->remove_extent = ext3_remove_blocks;
+       tree->remove_extent_credits = ext3_remove_blocks_credits;
+       tree->buffer = (void *) inode;
+       tree->buffer_len = sizeof(EXT3_I(inode)->i_data);
+       tree->cex = NULL;       /* FIXME: add cache store later */
+}
+
+#if 0
+static int
+ext3_ext_new_extent_cb(struct ext3_extents_tree *tree,
+                       struct ext3_ext_path *path,
+                       struct ext3_extent *newex, int exist)
+{
+       struct inode *inode = tree->inode;
+       int count, err, goal;
+       loff_t new_i_size;
+       handle_t *handle;
+       unsigned long pblock;
+
+       if (exist)
+               return EXT_CONTINUE;
+
+       count = ext3_ext_calc_credits_for_insert(tree, path);
+       handle = ext3_journal_start(inode, count + EXT3_ALLOC_NEEDED + 1);
+       if (IS_ERR(handle))
+               return PTR_ERR(handle);
+
+       goal = ext3_ext_find_goal(inode, path);
+       count = newex->e_num;
+#ifdef EXT3_MULTIBLOCK_ALLOCATOR
+       pblock = ext3_new_block(handle, inode, goal, &count, NULL, &err);
+       EXT_ASSERT(count <= num);
+       /* FIXME: error handling here */
+       EXT_ASSERT(err == 0);
+#else
+       pblock = 0;
+#endif
+
+       /* insert new extent */
+       newex->e_start = pblock;
+       newex->e_num = count;
+       err = ext3_ext_insert_extent(handle, tree, path, newex);
+       if (err)
+               goto out;
+
+       /* correct on-disk inode size */
+       if (newex->e_num > 0) {
+               new_i_size = (loff_t) newex->e_block + newex->e_num;
+               new_i_size = new_i_size << inode->i_blkbits;
+               if (new_i_size > i_size_read(inode))
+                       new_i_size = i_size_read(inode);
+               if (new_i_size > EXT3_I(inode)->i_disksize) {
+                       EXT3_I(inode)->i_disksize = new_i_size;
+                       err = ext3_mark_inode_dirty(handle, inode);
+               }
+       }
+
+out:
+       ext3_journal_stop(handle, inode);
+       return err;
+}
+
+
+int ext3_ext_allocate_nblocks(struct inode *inode, unsigned long block,
+                               unsigned long num)
+{
+       struct ext3_extents_tree tree;
+       int err;
+
+       ext_debug(&tree, "blocks %lu-%lu requested for inode %u\n",
+                       block, block + num,(unsigned) inode->i_ino);
+
+       ext3_init_tree_desc(&tree, inode);
+       down(&EXT3_I(inode)->truncate_sem);
+       err = ext3_ext_walk_space(&tree, block, num, ext3_ext_new_extent_cb);
+       ext3_ext_invalidate_cache(&tree);
+       up(&EXT3_I(inode)->truncate_sem);
+
+       return err;
+}
+#endif
+
+int ext3_ext_get_block(handle_t *handle, struct inode *inode,
+                       long iblock, struct buffer_head *bh_result, int create)
+{
+       struct ext3_ext_path *path = NULL;
+       struct ext3_extent newex;
+       struct ext3_extent *ex;
+       int goal, newblock, err = 0, depth;
+       struct ext3_extents_tree tree;
+
+       clear_bit(BH_New, &bh_result->b_state);
+       ext3_init_tree_desc(&tree, inode);
+       ext_debug(&tree, "block %d requested for inode %u\n",
+                       (int) iblock, (unsigned) inode->i_ino);
+       down_write(&EXT3_I(inode)->truncate_sem);
+
+       /* check in cache */
+       if (ext3_ext_in_cache(&tree, iblock, &newex)) {
+               if (newex.e_start == 0xffffffff && !create) {
+                       /* block isn't allocated yet and
+                        * user don't want to allocate it */
+                       goto out2;
+               } else if (newex.e_start) {
+                       /* block is already allocated */
+                       newblock = iblock - newex.e_block + newex.e_start;
+                       goto out;
+               }
+       }
+
+       /* find extent for this block */
+       path = ext3_ext_find_extent(&tree, iblock, NULL);
+       if (IS_ERR(path)) {
+               err = PTR_ERR(path);
+               goto out2;
+       }
+
+       depth = EXT_DEPTH(&tree);
+
+       /*
+        * consistent leaf must not be empty
+        * this situations is possible, though, _during_ tree modification
+        * this is why assert can't be put in ext3_ext_find_extent()
+        */
+       EXT_ASSERT(path[depth].p_ext != NULL || depth == 0);
+
+       if ((ex = path[depth].p_ext)) {
+               /* if found exent covers block, simple return it */
+               if (iblock >= ex->e_block && iblock < ex->e_block + ex->e_num) {
+                       newblock = iblock - ex->e_block + ex->e_start;
+                       ext_debug(&tree, "%d fit into %d:%d -> %d\n",
+                                       (int) iblock, ex->e_block, ex->e_num,
+                                       newblock);
+                       ext3_ext_put_in_cache(&tree, ex);
+                       goto out;
+               }
+       }
+
+       /*
+        * requested block isn't allocated yet
+        * we couldn't try to create block if create flag is zero 
+        */
+       if (!create) {
+               /* put just found gap into cache to speedup subsequest reqs */
+               ext3_ext_put_gap_in_cache(&tree, path, iblock);
+               goto out2;
+       }
+
+       /* allocate new block */
+       goal = ext3_ext_find_goal(inode, path);
+       newblock = ext3_new_block(handle, inode, goal, 0, 0, &err);
+       if (!newblock)
+               goto out2;
+       ext_debug(&tree, "allocate new block: goal %d, found %d\n",
+                       goal, newblock);
+
+       /* try to insert new extent into found leaf and return */
+       newex.e_block = iblock;
+       newex.e_start = newblock;
+       newex.e_num = 1;
+       err = ext3_ext_insert_extent(handle, &tree, path, &newex);
+       if (err)
+               goto out2;
+       
+       if (inode->i_size > EXT3_I(inode)->i_disksize)
+               EXT3_I(inode)->i_disksize = inode->i_size;
+
+       /* previous routine could use block we allocated */
+       newblock = newex.e_start;
+       set_bit(BH_New, &bh_result->b_state);
+
+       ext3_ext_put_in_cache(&tree, &newex);
+out:
+       ext3_ext_show_leaf(&tree, path);
+       set_bit(BH_Mapped, &bh_result->b_state);
+       bh_result->b_dev = inode->i_sb->s_dev;
+       bh_result->b_blocknr = newblock;
+out2:
+       if (path) {
+               ext3_ext_drop_refs(path);
+               kfree(path);
+       }
+       up_write(&EXT3_I(inode)->truncate_sem);
+
+       return err;     
+}
+
+void ext3_ext_truncate(struct inode * inode)
+{
+       struct address_space *mapping = inode->i_mapping;
+       struct super_block *sb = inode->i_sb;
+       struct ext3_extents_tree tree;
+       unsigned long last_block;
+       handle_t *handle;
+       int err = 0;
+
+       ext3_init_tree_desc(&tree, inode);
+
+       /*
+        * probably first extent we're gonna free will be last in block
+        */
+       err = ext3_writepage_trans_blocks(inode) + 3;
+       handle = ext3_journal_start(inode, err);
+       if (IS_ERR(handle))
+               return;
+
+       ext3_block_truncate_page(handle, mapping, inode->i_size);
+
+       down_write(&EXT3_I(inode)->truncate_sem);
+       ext3_ext_invalidate_cache(&tree);
+
+       /* 
+        * TODO: optimization is possible here
+        * probably we need not scaning at all,
+        * because page truncation is enough
+        */
+       if (ext3_orphan_add(handle, inode))
+               goto out_stop;
+
+       /* we have to know where to truncate from in crash case */
+       EXT3_I(inode)->i_disksize = inode->i_size;
+       ext3_mark_inode_dirty(handle, inode);
+
+       last_block = (inode->i_size + sb->s_blocksize - 1)
+                       >> EXT3_BLOCK_SIZE_BITS(sb);
+       err = ext3_ext_remove_space(&tree, last_block, 0xffffffff);
+       
+       /* In a multi-transaction truncate, we only make the final
+        * transaction synchronous */
+       if (IS_SYNC(inode))
+               handle->h_sync = 1;
+
+out_stop:
+       /*
+        * If this was a simple ftruncate(), and the file will remain alive
+        * then we need to clear up the orphan record which we created above.
+        * However, if this was a real unlink then we were called by
+        * ext3_delete_inode(), and we allow that function to clean up the
+        * orphan info for us.
+        */
+       if (inode->i_nlink)
+               ext3_orphan_del(handle, inode);
+
+       up_write(&EXT3_I(inode)->truncate_sem);
+       ext3_journal_stop(handle, inode);
+}
+
+/*
+ * this routine calculate max number of blocks we could modify
+ * in order to allocate new block for an inode
+ */
+int ext3_ext_writepage_trans_blocks(struct inode *inode, int num)
+{
+       struct ext3_extents_tree tree;
+       int needed;
+       
+       ext3_init_tree_desc(&tree, inode);
+       
+       needed = ext3_ext_calc_credits_for_insert(&tree, NULL);
+
+       /* caller want to allocate num blocks */
+       needed *= num;
+       
+#ifdef CONFIG_QUOTA
+       /* 
+        * FIXME: real calculation should be here
+        * it depends on blockmap format of qouta file
+        */
+       needed += 2 * EXT3_SINGLEDATA_TRANS_BLOCKS;
+#endif
+
+       return needed;
+}
+
+void ext3_extents_initialize_blockmap(handle_t *handle, struct inode *inode)
+{
+       struct ext3_extents_tree tree;
+
+       ext3_init_tree_desc(&tree, inode);
+       ext3_extent_tree_init(handle, &tree);
+}
+
+static int
+ext3_ext_store_extent_cb(struct ext3_extents_tree *tree,
+                       struct ext3_ext_path *path,
+                       struct ext3_extent *newex, int exist)
+{
+       struct ext3_extent_buf *buf = (struct ext3_extent_buf *) tree->private;
+
+       if (!exist)
+               return EXT_CONTINUE;
+       if (buf->err < 0)
+               return EXT_BREAK;
+       if (buf->cur - buf->buffer + sizeof(*newex) > buf->buflen)
+               return EXT_BREAK;
+
+       if (!copy_to_user(buf->cur, newex, sizeof(*newex))) {
+               buf->err++;
+               buf->cur += sizeof(*newex);
+       } else {
+               buf->err = -EFAULT;
+               return EXT_BREAK;
+       }
+       return EXT_CONTINUE;
+}
+
+static int
+ext3_ext_collect_stats_cb(struct ext3_extents_tree *tree,
+                       struct ext3_ext_path *path,
+                       struct ext3_extent *ex, int exist)
+{
+       struct ext3_extent_tree_stats *buf =
+               (struct ext3_extent_tree_stats *) tree->private;
+       int depth;
+
+       if (!exist)
+               return EXT_CONTINUE;
+
+       depth = EXT_DEPTH(tree);
+       buf->extents_num++;
+       if (path[depth].p_ext == EXT_FIRST_EXTENT(path[depth].p_hdr))
+               buf->leaf_num++;
+       return EXT_CONTINUE;
+}
+
+int ext3_ext_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
+               unsigned long arg)
+{
+       int err = 0;
+
+       if (cmd == EXT3_IOC_GET_EXTENTS) {
+               struct ext3_extent_buf buf;
+               struct ext3_extents_tree tree;
+
+               if (copy_from_user(&buf, (void *) arg, sizeof(buf)))
+                       return -EFAULT;
+
+               ext3_init_tree_desc(&tree, inode);
+               buf.cur = buf.buffer;
+               buf.err = 0;
+               tree.private = &buf;
+               err = ext3_ext_walk_space(&tree, buf.start, 0xffffffff,
+                                               ext3_ext_store_extent_cb);
+               if (err == 0)
+                       err = buf.err;
+       } else if (cmd == EXT3_IOC_GET_TREE_STATS) {
+               struct ext3_extent_tree_stats buf;
+               struct ext3_extents_tree tree;
+
+               ext3_init_tree_desc(&tree, inode);
+               buf.depth = EXT_DEPTH(&tree);
+               buf.extents_num = 0;
+               buf.leaf_num = 0;
+               tree.private = &buf;
+               err = ext3_ext_walk_space(&tree, 0, 0xffffffff,
+                                               ext3_ext_collect_stats_cb);
+               if (!err)
+                       err = copy_to_user((void *) arg, &buf, sizeof(buf));
+       } else if (cmd == EXT3_IOC_GET_TREE_DEPTH) {
+               struct ext3_extents_tree tree;
+               ext3_init_tree_desc(&tree, inode);
+               err = EXT_DEPTH(&tree);
+       }
+
+       return err;
+}
+
Index: linux-2.4.20/fs/ext3/ialloc.c
===================================================================
--- linux-2.4.20.orig/fs/ext3/ialloc.c  2004-01-23 19:00:25.000000000 +0300
+++ linux-2.4.20/fs/ext3/ialloc.c       2004-01-24 00:45:20.000000000 +0300
@@ -593,11 +593,13 @@
                iloc.bh = NULL;
                goto fail;
        }
+       if (test_opt(sb, EXTENTS)) {
+               EXT3_I(inode)->i_flags |= EXT3_EXTENTS_FL;
+               ext3_extents_initialize_blockmap(handle, inode);
+       }
        err = ext3_mark_iloc_dirty(handle, inode, &iloc);
        if (err) goto fail;
  
-
-       
        unlock_super (sb);
        if(DQUOT_ALLOC_INODE(inode)) {
                DQUOT_DROP(inode);
Index: linux-2.4.20/fs/ext3/inode.c
===================================================================
--- linux-2.4.20.orig/fs/ext3/inode.c   2004-01-23 19:00:25.000000000 +0300
+++ linux-2.4.20/fs/ext3/inode.c        2004-01-24 04:34:04.000000000 +0300
@@ -848,6 +848,15 @@
        goto reread;
 }
 
+static inline int
+ext3_get_block_wrap(handle_t *handle, struct inode *inode, long block,
+               struct buffer_head *bh, int create)
+{
+       if (EXT3_I(inode)->i_flags & EXT3_EXTENTS_FL)
+               return ext3_ext_get_block(handle, inode, block, bh, create);
+       return ext3_get_block_handle(handle, inode, block, bh, create);
+}
+
 /*
  * The BKL is not held on entry here.
  */
@@ -861,7 +870,7 @@
                handle = ext3_journal_current_handle();
                J_ASSERT(handle != 0);
        }
-       ret = ext3_get_block_handle(handle, inode, iblock, bh_result, create);
+       ret = ext3_get_block_wrap(handle, inode, iblock, bh_result, create);
        return ret;
 }
 
@@ -879,7 +888,7 @@
        dummy.b_state = 0;
        dummy.b_blocknr = -1000;
        buffer_trace_init(&dummy.b_history);
-       *errp = ext3_get_block_handle(handle, inode, block, &dummy, create);
+       *errp = ext3_get_block_wrap(handle, inode, block, &dummy, create);
        if (!*errp && buffer_mapped(&dummy)) {
                struct buffer_head *bh;
                bh = sb_getblk(inode->i_sb, dummy.b_blocknr);
@@ -1403,7 +1412,7 @@
  * This required during truncate. We need to physically zero the tail end
  * of that block so it doesn't yield old data if the file is later grown.
  */
-static int ext3_block_truncate_page(handle_t *handle,
+int ext3_block_truncate_page(handle_t *handle,
                struct address_space *mapping, loff_t from)
 {
        unsigned long index = from >> PAGE_CACHE_SHIFT;
@@ -1888,6 +1897,9 @@
 
        ext3_discard_prealloc(inode);
 
+       if (EXT3_I(inode)->i_flags & EXT3_EXTENTS_FL)
+               return ext3_ext_truncate(inode);
+
        handle = start_transaction(inode);
        if (IS_ERR(handle))
                return;         /* AKPM: return what? */
@@ -2537,6 +2549,9 @@
        int indirects = (EXT3_NDIR_BLOCKS % bpp) ? 5 : 3;
        int ret;
        
+       if (EXT3_I(inode)->i_flags & EXT3_EXTENTS_FL)
+               return ext3_ext_writepage_trans_blocks(inode, bpp);
+
        if (ext3_should_journal_data(inode))
                ret = 3 * (bpp + indirects) + 2;
        else
@@ -2973,7 +2988,7 @@
 
        /* alloc blocks one by one */
        for (i = 0; i < nblocks; i++) {
-               ret = ext3_get_block_handle(handle, inode, blocks[i],
+               ret = ext3_get_block_wrap(handle, inode, blocks[i],
                                                &bh_tmp, 1);
                if (ret)
                        break;
@@ -3049,7 +3064,7 @@
                 if (blocks[i] != 0)
                         continue;
 
-                rc = ext3_get_block_handle(handle, inode, iblock, &bh, 1);
+                rc = ext3_get_block_wrap(handle, inode, iblock, &bh, 1);
                 if (rc) {
                         printk(KERN_INFO "ext3_map_inode_page: error %d "
                                "allocating block %ld\n", rc, iblock);
Index: linux-2.4.20/fs/ext3/Makefile
===================================================================
--- linux-2.4.20.orig/fs/ext3/Makefile  2004-01-23 19:00:42.000000000 +0300
+++ linux-2.4.20/fs/ext3/Makefile       2004-01-24 00:45:20.000000000 +0300
@@ -13,7 +13,7 @@
 
 obj-y    := balloc.o bitmap.o dir.o file.o fsync.o ialloc.o inode.o iopen.o \
                ioctl.o namei.o super.o symlink.o hash.o ext3-exports.o \
-               xattr_trusted.o
+               xattr_trusted.o extents.o
 obj-m    := $(O_TARGET)
 
 export-objs += xattr.o
Index: linux-2.4.20/fs/ext3/super.c
===================================================================
--- linux-2.4.20.orig/fs/ext3/super.c   2004-01-23 19:00:25.000000000 +0300
+++ linux-2.4.20/fs/ext3/super.c        2004-01-24 04:30:14.000000000 +0300
@@ -623,6 +623,7 @@
        int i;
 
        J_ASSERT(sbi->s_delete_inodes == 0);
+       ext3_ext_release(sb);
        ext3_xattr_put_super(sb);
        journal_destroy(sbi->s_journal);
        if (!(sb->s_flags & MS_RDONLY)) {
@@ -796,6 +797,10 @@
                                return 0;
                        }
                }
+               else if (!strcmp (this_char, "extents"))
+                       set_opt (*mount_options, EXTENTS);
+               else if (!strcmp (this_char, "extdebug"))
+                       set_opt (*mount_options, EXTDEBUG);
                else if (!strcmp (this_char, "grpid") ||
                         !strcmp (this_char, "bsdgroups"))
                        set_opt (*mount_options, GRPID);
@@ -1485,6 +1490,8 @@
                test_opt(sb,DATA_FLAGS) == EXT3_MOUNT_ORDERED_DATA ? "ordered":
                "writeback");
 
+       ext3_ext_init(sb);
+
        return sb;
 
 failed_mount3:
Index: linux-2.4.20/fs/ext3/ioctl.c
===================================================================
--- linux-2.4.20.orig/fs/ext3/ioctl.c   2004-01-13 17:00:09.000000000 +0300
+++ linux-2.4.20/fs/ext3/ioctl.c        2004-01-24 14:54:31.000000000 +0300
@@ -189,6 +189,10 @@
                        return ret;
                }
 #endif
+       case EXT3_IOC_GET_EXTENTS:
+       case EXT3_IOC_GET_TREE_STATS:
+       case EXT3_IOC_GET_TREE_DEPTH:
+               return ext3_ext_ioctl(inode, filp, cmd, arg);
        default:
                return -ENOTTY;
        }
Index: linux-2.4.20/include/linux/ext3_fs.h
===================================================================
--- linux-2.4.20.orig/include/linux/ext3_fs.h   2004-01-23 19:00:25.000000000 +0300
+++ linux-2.4.20/include/linux/ext3_fs.h        2004-01-24 01:28:06.000000000 +0300
@@ -184,6 +184,7 @@
 #define EXT3_IMAGIC_FL                 0x00002000 /* AFS directory */
 #define EXT3_JOURNAL_DATA_FL           0x00004000 /* file data should be journaled */
 #define EXT3_RESERVED_FL               0x80000000 /* reserved for ext3 lib */
+#define EXT3_EXTENTS_FL                        0x00080000 /* Inode uses extents */
 
 #define EXT3_FL_USER_VISIBLE           0x00005FFF /* User visible flags */
 #define EXT3_FL_USER_MODIFIABLE                0x000000FF /* User modifiable flags */
@@ -208,6 +209,9 @@
 #ifdef CONFIG_JBD_DEBUG
 #define EXT3_IOC_WAIT_FOR_READONLY     _IOR('f', 99, long)
 #endif
+#define        EXT3_IOC_GET_EXTENTS            _IOR('f', 5, long)
+#define        EXT3_IOC_GET_TREE_DEPTH         _IOR('f', 6, long)
+#define        EXT3_IOC_GET_TREE_STATS         _IOR('f', 7, long)
 
 /*
  * Structure of an inode on the disk
@@ -327,6 +331,8 @@
 #define EXT3_MOUNT_IOPEN               0x8000  /* Allow access via iopen */
 #define EXT3_MOUNT_IOPEN_NOPRIV                0x10000 /* Make iopen world-readable */
 #define EXT3_MOUNT_ASYNCDEL            0x20000 /* Delayed deletion */
+#define EXT3_MOUNT_EXTENTS             0x100000/* Extents support */
+#define EXT3_MOUNT_EXTDEBUG            0x200000/* Extents debug */
 
 /* Compatibility, for having both ext2_fs.h and ext3_fs.h included at once */
 #ifndef _LINUX_EXT2_FS_H
@@ -687,6 +693,7 @@
 extern unsigned long ext3_count_free (struct buffer_head *, unsigned);
 
 /* inode.c */
+extern int ext3_block_truncate_page(handle_t *, struct address_space *, loff_t);
 extern int ext3_forget(handle_t *, int, struct inode *, struct buffer_head *, int);
 extern struct buffer_head * ext3_getblk (handle_t *, struct inode *, long, int, int *);
 extern struct buffer_head * ext3_bread (handle_t *, struct inode *, int, int, int *);
@@ -767,6 +774,14 @@
 extern struct inode_operations ext3_symlink_inode_operations;
 extern struct inode_operations ext3_fast_symlink_inode_operations;
 
+/* extents.c */
+extern int ext3_ext_writepage_trans_blocks(struct inode *, int);
+extern int ext3_ext_get_block(handle_t *, struct inode *, long,
+                               struct buffer_head *, int);
+extern void ext3_ext_truncate(struct inode *);
+extern void ext3_ext_init(struct super_block *);
+extern void ext3_ext_release(struct super_block *);
+extern void ext3_extents_initialize_blockmap(handle_t *, struct inode *);
 
 #endif /* __KERNEL__ */
 
Index: linux-2.4.20/include/linux/ext3_extents.h
===================================================================
--- linux-2.4.20.orig/include/linux/ext3_extents.h      2003-01-30 13:24:37.000000000 +0300
+++ linux-2.4.20/include/linux/ext3_extents.h   2004-01-24 15:15:11.000000000 +0300
@@ -0,0 +1,207 @@
+/*
+ * Copyright (C) 2003 Alex Tomas <alex@clusterfs.com>
+ *
+ * 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-
+ */
+
+
+/*
+ * with AGRESSIVE_TEST defined capacity of index/leaf blocks
+ * become very little, so index split, in-depth growing and
+ * other hard changes happens much more often
+ * this is for debug purposes only
+ */
+#define AGRESSIVE_TEST_
+
+/*
+ * if CHECK_BINSEARCH defined, then results of binary search
+ * will be checked by linear search
+ */
+#define CHECK_BINSEARCH_
+
+/*
+ * if EXT_DEBUG is defined you can use 'extdebug' mount option
+ * to get lots of info what's going on
+ */
+#define EXT_DEBUG
+#ifdef EXT_DEBUG
+#define ext_debug(tree,fmt,a...)                       \
+do {                                                   \
+       if (test_opt((tree)->inode->i_sb, EXTDEBUG))    \
+               printk(fmt, ##a);                       \
+} while (0);
+#else
+#define ext_debug(tree,fmt,a...)
+#endif
+
+/*
+ * if EXT_STATS is defined then stats numbers are collected
+ * these number will be displayed at umount time
+ */
+#define EXT_STATS_
+
+
+#define EXT3_ALLOC_NEEDED      2       /* block bitmap + group descriptor */
+
+/*
+ * ext3_inode has i_block array (total 60 bytes)
+ * first 4 bytes are used to store:
+ *  - tree depth (0 mean there is no tree yet. all extents in the inode)
+ *  - number of alive extents in the inode
+ */
+
+/*
+ * this is extent on-disk structure
+ * it's used at the bottom of the tree
+ */
+struct ext3_extent {
+       __u32   e_block;        /* first logical block extent covers */
+       __u32   e_start;        /* first physical block extents lives */
+       __u32   e_num;          /* number of blocks covered by extent */
+};
+
+/*
+ * this is index on-disk structure
+ * it's used at all the levels, but the bottom
+ */
+struct ext3_extent_idx {
+       __u32   e_block;        /* index covers logical blocks from 'block' */
+       __u32   e_leaf;         /* pointer to the physical block of the next *
+                                * level. leaf or next index could bet here */
+};
+
+/*
+ * each block (leaves and indexes), even inode-stored has header
+ */
+struct ext3_extent_header {    
+       __u16   e_magic;        /* probably will support different formats */   
+       __u16   e_num;          /* number of valid entries */
+       __u16   e_max;          /* capacity of store in entries */
+       __u16   e_depth;        /* has tree real underlaying blocks? */
+};
+
+/*
+ * array of ext3_ext_path contains path to some extent
+ * creation/lookup routines use it for traversal/splitting/etc
+ * truncate uses it to simulate recursive walking
+ */
+struct ext3_ext_path {
+       __u32                           p_block;
+       __u16                           p_depth;
+       struct ext3_extent              *p_ext;
+       struct ext3_extent_idx          *p_idx;
+       struct ext3_extent_header       *p_hdr;
+       struct buffer_head              *p_bh;
+};
+
+/*
+ * structure for external API
+ */
+
+
+/*
+ * ext3_extents_tree is used to pass initial information
+ * to top-level extents API
+ */
+struct ext3_extents_tree {
+       struct inode *inode;    /* inode which tree belongs to */
+       void *root;             /* ptr to data top of tree resides at */
+       void *buffer;           /* will be passed as arg to ^^ routines */
+       int buffer_len;
+       void *private;
+       struct ext3_extent *cex;/* last found extent */
+       int (*get_write_access)(handle_t *h, void *buffer);
+       int (*mark_buffer_dirty)(handle_t *h, void *buffer);
+       int (*mergable)(struct ext3_extent *ex1, struct ext3_extent *ex2);
+       int (*remove_extent_credits)(struct ext3_extents_tree *,
+                                       struct ext3_extent *, unsigned long,
+                                       unsigned long);
+       int (*remove_extent)(struct ext3_extents_tree *,
+                               struct ext3_extent *, unsigned long,
+                               unsigned long);
+       int (*new_block)(handle_t *, struct ext3_extents_tree *,
+                               struct ext3_ext_path *, struct ext3_extent *,
+                               int *);
+};
+
+/*
+ * to be called by ext3_ext_walk_space()
+ * negative retcode - error
+ * positive retcode - signal for ext3_ext_walk_space(), see below
+ * callback must return valid extent (passed or newly created)
+ */
+typedef int (*ext_prepare_callback)(struct ext3_extents_tree *,
+                                       struct ext3_ext_path *,
+                                       struct ext3_extent *, int);
+
+#define EXT_CONTINUE   0
+#define EXT_BREAK      1
+
+
+#define EXT_FIRST_EXTENT(__hdr__) \
+       ((struct ext3_extent *) (((char *) (__hdr__)) +         \
+                                sizeof(struct ext3_extent_header)))
+#define EXT_FIRST_INDEX(__hdr__) \
+       ((struct ext3_extent_idx *) (((char *) (__hdr__)) +     \
+                                    sizeof(struct ext3_extent_header)))
+#define EXT_HAS_FREE_INDEX(__path__) \
+       ((__path__)->p_hdr->e_num < (__path__)->p_hdr->e_max)
+#define EXT_LAST_EXTENT(__hdr__) \
+       (EXT_FIRST_EXTENT((__hdr__)) + (__hdr__)->e_num - 1)
+#define EXT_LAST_INDEX(__hdr__) \
+       (EXT_FIRST_INDEX((__hdr__)) + (__hdr__)->e_num - 1)
+#define EXT_MAX_EXTENT(__hdr__) \
+       (EXT_FIRST_EXTENT((__hdr__)) + (__hdr__)->e_max - 1)
+#define EXT_MAX_INDEX(__hdr__) \
+       (EXT_FIRST_INDEX((__hdr__)) + (__hdr__)->e_max - 1)
+
+#define EXT_ROOT_HDR(tree) \
+       ((struct ext3_extent_header *) (tree)->root)
+#define EXT_BLOCK_HDR(bh) \
+       ((struct ext3_extent_header *) (bh)->b_data)
+#define EXT_DEPTH(_t_) \
+       (((struct ext3_extent_header *)((_t_)->root))->e_depth)
+
+
+#define EXT_ASSERT(__x__) if (!(__x__)) BUG();
+
+
+/*
+ * this structure is used to gather extents from the tree via ioctl
+ */
+struct ext3_extent_buf {
+       unsigned long start;
+       int buflen;
+       void *buffer;
+       void *cur;
+       int err;
+};
+
+/*
+ * this structure is used to collect stats info about the tree
+ */
+struct ext3_extent_tree_stats {
+       int depth;
+       int extents_num;
+       int leaf_num;
+};
+
+extern int ext3_extent_tree_init(handle_t *, struct ext3_extents_tree *);
+extern int ext3_ext_calc_credits_for_insert(struct ext3_extents_tree *, struct ext3_ext_path *);
+extern int ext3_ext_insert_extent(handle_t *, struct ext3_extents_tree *, struct ext3_ext_path *, struct ext3_extent *);
+extern int ext3_ext_walk_space(struct ext3_extents_tree *, unsigned long, unsigned long, ext_prepare_callback);
+extern int ext3_ext_remove_space(struct ext3_extents_tree *, unsigned long, unsigned long);
+extern struct ext3_ext_path * ext3_ext_find_extent(struct ext3_extents_tree *, int, struct ext3_ext_path *);
+
+