Merge ../torvalds-2.6/

1 files changed, 994 insertions, 0 deletions

diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c
new file mode 100644
index 000000000000..f2fb40cd296a
--- /dev/null
+++ b/fs/ocfs2/extent_map.c
@@ -0,0 +1,994 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * extent_map.c
+ *
+ * In-memory extent map for OCFS2.  Man, this code was prettier in
+ * the library.
+ *
+ * Copyright (C) 2004 Oracle.  All rights reserved.
+ *
+ * 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
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/rbtree.h>
+
+#define MLOG_MASK_PREFIX ML_EXTENT_MAP
+#include <cluster/masklog.h>
+
+#include "ocfs2.h"
+
+#include "extent_map.h"
+#include "inode.h"
+#include "super.h"
+
+#include "buffer_head_io.h"
+
+
+/*
+ * SUCK SUCK SUCK
+ * Our headers are so bad that struct ocfs2_extent_map is in ocfs.h
+ */
+
+struct ocfs2_extent_map_entry {
+        struct rb_node e_node;
+        int e_tree_depth;
+        struct ocfs2_extent_rec e_rec;
+};
+
+struct ocfs2_em_insert_context {
+        int need_left;
+        int need_right;
+        struct ocfs2_extent_map_entry *new_ent;
+        struct ocfs2_extent_map_entry *old_ent;
+        struct ocfs2_extent_map_entry *left_ent;
+        struct ocfs2_extent_map_entry *right_ent;
+};
+
+static kmem_cache_t *ocfs2_em_ent_cachep = NULL;
+
+
+static struct ocfs2_extent_map_entry *
+ocfs2_extent_map_lookup(struct ocfs2_extent_map *em,
+                        u32 cpos, u32 clusters,
+                        struct rb_node ***ret_p,
+                        struct rb_node **ret_parent);
+static int ocfs2_extent_map_insert(struct inode *inode,
+                                   struct ocfs2_extent_rec *rec,
+                                   int tree_depth);
+static int ocfs2_extent_map_insert_entry(struct ocfs2_extent_map *em,
+                                         struct ocfs2_extent_map_entry *ent);
+static int ocfs2_extent_map_find_leaf(struct inode *inode,
+                                      u32 cpos, u32 clusters,
+                                      struct ocfs2_extent_list *el);
+static int ocfs2_extent_map_lookup_read(struct inode *inode,
+                                        u32 cpos, u32 clusters,
+                                        struct ocfs2_extent_map_entry **ret_ent);
+static int ocfs2_extent_map_try_insert(struct inode *inode,
+                                       struct ocfs2_extent_rec *rec,
+                                       int tree_depth,
+                                       struct ocfs2_em_insert_context *ctxt);
+
+/* returns 1 only if the rec contains all the given clusters -- that is that
+ * rec's cpos is <= the cluster cpos and that the rec endpoint (cpos +
+ * clusters) is >= the argument's endpoint */
+static int ocfs2_extent_rec_contains_clusters(struct ocfs2_extent_rec *rec,
+                                              u32 cpos, u32 clusters)
+{
+        if (le32_to_cpu(rec->e_cpos) > cpos)
+                return 0;
+        if (cpos + clusters > le32_to_cpu(rec->e_cpos) + 
+                              le32_to_cpu(rec->e_clusters))
+                return 0;
+        return 1;
+}
+
+
+/*
+ * Find an entry in the tree that intersects the region passed in.
+ * Note that this will find straddled intervals, it is up to the
+ * callers to enforce any boundary conditions.
+ *
+ * Callers must hold ip_lock.  This lookup is not guaranteed to return
+ * a tree_depth 0 match, and as such can race inserts if the lock
+ * were not held.
+ *
+ * The rb_node garbage lets insertion share the search.  Trivial
+ * callers pass NULL.
+ */
+static struct ocfs2_extent_map_entry *
+ocfs2_extent_map_lookup(struct ocfs2_extent_map *em,
+                        u32 cpos, u32 clusters,
+                        struct rb_node ***ret_p,
+                        struct rb_node **ret_parent)
+{
+        struct rb_node **p = &em->em_extents.rb_node;
+        struct rb_node *parent = NULL;
+        struct ocfs2_extent_map_entry *ent = NULL;
+
+        while (*p)
+        {
+                parent = *p;
+                ent = rb_entry(parent, struct ocfs2_extent_map_entry,
+                               e_node);
+                if ((cpos + clusters) <= le32_to_cpu(ent->e_rec.e_cpos)) {
+                        p = &(*p)->rb_left;
+                        ent = NULL;
+                } else if (cpos >= (le32_to_cpu(ent->e_rec.e_cpos) +
+                                    le32_to_cpu(ent->e_rec.e_clusters))) {
+                        p = &(*p)->rb_right;
+                        ent = NULL;
+                } else
+                        break;
+        }
+
+        if (ret_p != NULL)
+                *ret_p = p;
+        if (ret_parent != NULL)
+                *ret_parent = parent;
+        return ent;
+}
+
+/*
+ * Find the leaf containing the interval we want.  While we're on our
+ * way down the tree, fill in every record we see at any depth, because
+ * we might want it later.
+ *
+ * Note that this code is run without ip_lock.  That's because it
+ * sleeps while reading.  If someone is also filling the extent list at
+ * the same time we are, we might have to restart.
+ */
+static int ocfs2_extent_map_find_leaf(struct inode *inode,
+                                      u32 cpos, u32 clusters,
+                                      struct ocfs2_extent_list *el)
+{
+        int i, ret;
+        struct buffer_head *eb_bh = NULL;
+        u64 blkno;
+        u32 rec_end;
+        struct ocfs2_extent_block *eb;
+        struct ocfs2_extent_rec *rec;
+
+        /*
+         * The bh data containing the el cannot change here, because
+         * we hold alloc_sem.  So we can do this without other
+         * locks.
+         */
+        while (el->l_tree_depth)
+        {
+                blkno = 0;
+                for (i = 0; i < le16_to_cpu(el->l_next_free_rec); i++) {
+                        rec = &el->l_recs[i];
+                        rec_end = (le32_to_cpu(rec->e_cpos) +
+                                   le32_to_cpu(rec->e_clusters));
+
+                        ret = -EBADR;
+                        if (rec_end > OCFS2_I(inode)->ip_clusters) {
+                                mlog_errno(ret);
+                                goto out_free;
+                        }
+
+                        if (rec_end <= cpos) {
+                                ret = ocfs2_extent_map_insert(inode, rec,
+                                                le16_to_cpu(el->l_tree_depth));
+                                if (ret && (ret != -EEXIST)) {
+                                        mlog_errno(ret);
+                                        goto out_free;
+                                }
+                                continue;
+                        }
+                        if ((cpos + clusters) <= le32_to_cpu(rec->e_cpos)) {
+                                ret = ocfs2_extent_map_insert(inode, rec,
+                                                le16_to_cpu(el->l_tree_depth));
+                                if (ret && (ret != -EEXIST)) {
+                                        mlog_errno(ret);
+                                        goto out_free;
+                                }
+                                continue;
+                        }
+
+                        /*
+                         * We've found a record that matches our
+                         * interval.  We don't insert it because we're
+                         * about to traverse it.
+                         */
+
+                        /* Check to see if we're stradling */
+                        ret = -ESRCH;
+                        if (!ocfs2_extent_rec_contains_clusters(rec,
+                                                                cpos,
+                                                                clusters)) {
+                                mlog_errno(ret);
+                                goto out_free;
+                        }
+
+                        /*
+                         * If we've already found a record, the el has
+                         * two records covering the same interval.
+                         * EEEK!
+                         */
+                        ret = -EBADR;
+                        if (blkno) {
+                                mlog_errno(ret);
+                                goto out_free;
+                        }
+
+                        blkno = le64_to_cpu(rec->e_blkno);
+                }
+
+                /*
+                 * We don't support holes, and we're still up
+                 * in the branches, so we'd better have found someone
+                 */
+                ret = -EBADR;
+                if (!blkno) {
+                        mlog_errno(ret);
+                        goto out_free;
+                }
+
+                if (eb_bh) {
+                        brelse(eb_bh);
+                        eb_bh = NULL;
+                }
+                ret = ocfs2_read_block(OCFS2_SB(inode->i_sb),
+                                       blkno, &eb_bh, OCFS2_BH_CACHED,
+                                       inode);
+                if (ret) {
+                        mlog_errno(ret);
+                        goto out_free;
+                }
+                eb = (struct ocfs2_extent_block *)eb_bh->b_data;
+                if (!OCFS2_IS_VALID_EXTENT_BLOCK(eb)) {
+                        OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb, eb);
+                        ret = -EIO;
+                        goto out_free;
+                }
+                el = &eb->h_list;
+        }
+
+        if (el->l_tree_depth)
+                BUG();
+
+        for (i = 0; i < le16_to_cpu(el->l_next_free_rec); i++) {
+                rec = &el->l_recs[i];
+                ret = ocfs2_extent_map_insert(inode, rec,
+                                              le16_to_cpu(el->l_tree_depth));
+                if (ret) {
+                        mlog_errno(ret);
+                        goto out_free;
+                }
+        }
+
+        ret = 0;
+
+out_free:
+        if (eb_bh)
+                brelse(eb_bh);
+
+        return ret;
+}
+
+/*
+ * This lookup actually will read from disk.  It has one invariant:
+ * It will never re-traverse blocks.  This means that all inserts should
+ * be new regions or more granular regions (both allowed by insert).
+ */
+static int ocfs2_extent_map_lookup_read(struct inode *inode,
+                                        u32 cpos,
+                                        u32 clusters,
+                                        struct ocfs2_extent_map_entry **ret_ent)
+{
+        int ret;
+        u64 blkno;
+        struct ocfs2_extent_map *em = &OCFS2_I(inode)->ip_map;
+        struct ocfs2_extent_map_entry *ent;
+        struct buffer_head *bh = NULL;
+        struct ocfs2_extent_block *eb;
+        struct ocfs2_dinode *di;
+        struct ocfs2_extent_list *el;
+
+        spin_lock(&OCFS2_I(inode)->ip_lock);
+        ent = ocfs2_extent_map_lookup(em, cpos, clusters, NULL, NULL);
+        if (ent) {
+                if (!ent->e_tree_depth) {
+                        spin_unlock(&OCFS2_I(inode)->ip_lock);
+                        *ret_ent = ent;
+                        return 0;
+                }
+                blkno = le64_to_cpu(ent->e_rec.e_blkno);
+                spin_unlock(&OCFS2_I(inode)->ip_lock);
+
+                ret = ocfs2_read_block(OCFS2_SB(inode->i_sb), blkno, &bh,
+                                       OCFS2_BH_CACHED, inode);
+                if (ret) {
+                        mlog_errno(ret);
+                        if (bh)
+                                brelse(bh);
+                        return ret;
+                }
+                eb = (struct ocfs2_extent_block *)bh->b_data;
+                if (!OCFS2_IS_VALID_EXTENT_BLOCK(eb)) {
+                        OCFS2_RO_ON_INVALID_EXTENT_BLOCK(inode->i_sb, eb);
+                        brelse(bh);
+                        return -EIO;
+                }
+                el = &eb->h_list;
+        } else {
+                spin_unlock(&OCFS2_I(inode)->ip_lock);
+
+                ret = ocfs2_read_block(OCFS2_SB(inode->i_sb),
+                                       OCFS2_I(inode)->ip_blkno, &bh,
+                                       OCFS2_BH_CACHED, inode);
+                if (ret) {
+                        mlog_errno(ret);
+                        if (bh)
+                                brelse(bh);
+                        return ret;
+                }
+                di = (struct ocfs2_dinode *)bh->b_data;
+                if (!OCFS2_IS_VALID_DINODE(di)) {
+                        brelse(bh);
+                        OCFS2_RO_ON_INVALID_DINODE(inode->i_sb, di);
+                        return -EIO;
+                }
+                el = &di->id2.i_list;
+        }
+
+        ret = ocfs2_extent_map_find_leaf(inode, cpos, clusters, el);
+        brelse(bh);
+        if (ret) {
+                mlog_errno(ret);
+                return ret;
+        }
+
+        ent = ocfs2_extent_map_lookup(em, cpos, clusters, NULL, NULL);
+        if (!ent) {
+                ret = -ESRCH;
+                mlog_errno(ret);
+                return ret;
+        }
+
+        if (ent->e_tree_depth)
+                BUG();  /* FIXME: Make sure this isn't a corruption */
+
+        *ret_ent = ent;
+
+        return 0;
+}
+
+/*
+ * Callers must hold ip_lock.  This can insert pieces of the tree,
+ * thus racing lookup if the lock weren't held.
+ */
+static int ocfs2_extent_map_insert_entry(struct ocfs2_extent_map *em,
+                                         struct ocfs2_extent_map_entry *ent)
+{
+        struct rb_node **p, *parent;
+        struct ocfs2_extent_map_entry *old_ent;
+
+        old_ent = ocfs2_extent_map_lookup(em, le32_to_cpu(ent->e_rec.e_cpos),
+                                          le32_to_cpu(ent->e_rec.e_clusters),
+                                          &p, &parent);
+        if (old_ent)
+                return -EEXIST;
+
+        rb_link_node(&ent->e_node, parent, p);
+        rb_insert_color(&ent->e_node, &em->em_extents);
+
+        return 0;
+}
+
+
+/*
+ * Simple rule: on any return code other than -EAGAIN, anything left
+ * in the insert_context will be freed.
+ */
+static int ocfs2_extent_map_try_insert(struct inode *inode,
+                                       struct ocfs2_extent_rec *rec,
+                                       int tree_depth,
+                                       struct ocfs2_em_insert_context *ctxt)
+{
+        int ret;
+        struct ocfs2_extent_map *em = &OCFS2_I(inode)->ip_map;
+        struct ocfs2_extent_map_entry *old_ent;
+
+        ctxt->need_left = 0;
+        ctxt->need_right = 0;
+        ctxt->old_ent = NULL;
+
+        spin_lock(&OCFS2_I(inode)->ip_lock);
+        ret = ocfs2_extent_map_insert_entry(em, ctxt->new_ent);
+        if (!ret) {
+                ctxt->new_ent = NULL;
+                goto out_unlock;
+        }
+
+        old_ent = ocfs2_extent_map_lookup(em, le32_to_cpu(rec->e_cpos),
+                                          le32_to_cpu(rec->e_clusters), NULL,
+                                          NULL);
+
+        if (!old_ent)
+                BUG();
+
+        ret = -EEXIST;
+        if (old_ent->e_tree_depth < tree_depth)
+                goto out_unlock;
+
+        if (old_ent->e_tree_depth == tree_depth) {
+                if (!memcmp(rec, &old_ent->e_rec,
+                            sizeof(struct ocfs2_extent_rec)))
+                        ret = 0;
+
+                /* FIXME: Should this be ESRCH/EBADR??? */
+                goto out_unlock;
+        }
+
+        /*
+         * We do it in this order specifically so that no actual tree
+         * changes occur until we have all the pieces we need.  We
+         * don't want malloc failures to leave an inconsistent tree.
+         * Whenever we drop the lock, another process could be
+         * inserting.  Also note that, if another process just beat us
+         * to an insert, we might not need the same pieces we needed
+         * the first go round.  In the end, the pieces we need will
+         * be used, and the pieces we don't will be freed.
+         */
+        ctxt->need_left = !!(le32_to_cpu(rec->e_cpos) >
+                             le32_to_cpu(old_ent->e_rec.e_cpos));
+        ctxt->need_right = !!((le32_to_cpu(old_ent->e_rec.e_cpos) +
+                               le32_to_cpu(old_ent->e_rec.e_clusters)) >
+                              (le32_to_cpu(rec->e_cpos) + le32_to_cpu(rec->e_clusters)));
+        ret = -EAGAIN;
+        if (ctxt->need_left) {
+                if (!ctxt->left_ent)
+                        goto out_unlock;
+                *(ctxt->left_ent) = *old_ent;
+                ctxt->left_ent->e_rec.e_clusters =
+                        cpu_to_le32(le32_to_cpu(rec->e_cpos) -
+                                    le32_to_cpu(ctxt->left_ent->e_rec.e_cpos));
+        }
+        if (ctxt->need_right) {
+                if (!ctxt->right_ent)
+                        goto out_unlock;
+                *(ctxt->right_ent) = *old_ent;
+                ctxt->right_ent->e_rec.e_cpos =
+                        cpu_to_le32(le32_to_cpu(rec->e_cpos) +
+                                    le32_to_cpu(rec->e_clusters));
+                ctxt->right_ent->e_rec.e_clusters =
+                        cpu_to_le32((le32_to_cpu(old_ent->e_rec.e_cpos) +
+                                     le32_to_cpu(old_ent->e_rec.e_clusters)) -
+                                    le32_to_cpu(ctxt->right_ent->e_rec.e_cpos));
+        }
+
+        rb_erase(&old_ent->e_node, &em->em_extents);
+        /* Now that he's erased, set him up for deletion */
+        ctxt->old_ent = old_ent;
+
+        if (ctxt->need_left) {
+                ret = ocfs2_extent_map_insert_entry(em,
+                                                    ctxt->left_ent);
+                if (ret)
+                        goto out_unlock;
+                ctxt->left_ent = NULL;
+        }
+
+        if (ctxt->need_right) {
+                ret = ocfs2_extent_map_insert_entry(em,
+                                                    ctxt->right_ent);
+                if (ret)
+                        goto out_unlock;
+                ctxt->right_ent = NULL;
+        }
+
+        ret = ocfs2_extent_map_insert_entry(em, ctxt->new_ent);
+
+        if (!ret)
+                ctxt->new_ent = NULL;
+
+out_unlock:
+        spin_unlock(&OCFS2_I(inode)->ip_lock);
+
+        return ret;
+}
+
+
+static int ocfs2_extent_map_insert(struct inode *inode,
+                                   struct ocfs2_extent_rec *rec,
+                                   int tree_depth)
+{
+        int ret;
+        struct ocfs2_em_insert_context ctxt = {0, };
+
+        if ((le32_to_cpu(rec->e_cpos) + le32_to_cpu(rec->e_clusters)) >
+            OCFS2_I(inode)->ip_map.em_clusters) {
+                ret = -EBADR;
+                mlog_errno(ret);
+                return ret;
+        }
+
+        /* Zero e_clusters means a truncated tail record.  It better be EOF */
+        if (!rec->e_clusters) {
+                if ((le32_to_cpu(rec->e_cpos) + le32_to_cpu(rec->e_clusters)) !=
+                    OCFS2_I(inode)->ip_map.em_clusters) {
+                        ret = -EBADR;
+                        mlog_errno(ret);
+                        return ret;
+                }
+
+                /* Ignore the truncated tail */
+                return 0;
+        }
+
+        ret = -ENOMEM;
+        ctxt.new_ent = kmem_cache_alloc(ocfs2_em_ent_cachep,
+                                        GFP_KERNEL);
+        if (!ctxt.new_ent) {
+                mlog_errno(ret);
+                return ret;
+        }
+
+        ctxt.new_ent->e_rec = *rec;
+        ctxt.new_ent->e_tree_depth = tree_depth;
+
+        do {
+                ret = -ENOMEM;
+                if (ctxt.need_left && !ctxt.left_ent) {
+                        ctxt.left_ent =
+                                kmem_cache_alloc(ocfs2_em_ent_cachep,
+                                                 GFP_KERNEL);
+                        if (!ctxt.left_ent)
+                                break;
+                }
+                if (ctxt.need_right && !ctxt.right_ent) {
+                        ctxt.right_ent =
+                                kmem_cache_alloc(ocfs2_em_ent_cachep,
+                                                 GFP_KERNEL);
+                        if (!ctxt.right_ent)
+                                break;
+                }
+
+                ret = ocfs2_extent_map_try_insert(inode, rec,
+                                                  tree_depth, &ctxt);
+        } while (ret == -EAGAIN);
+
+        if (ret < 0)
+                mlog_errno(ret);
+
+        if (ctxt.left_ent)
+                kmem_cache_free(ocfs2_em_ent_cachep, ctxt.left_ent);
+        if (ctxt.right_ent)
+                kmem_cache_free(ocfs2_em_ent_cachep, ctxt.right_ent);
+        if (ctxt.old_ent)
+                kmem_cache_free(ocfs2_em_ent_cachep, ctxt.old_ent);
+        if (ctxt.new_ent)
+                kmem_cache_free(ocfs2_em_ent_cachep, ctxt.new_ent);
+
+        return ret;
+}
+
+/*
+ * Append this record to the tail of the extent map.  It must be
+ * tree_depth 0.  The record might be an extension of an existing
+ * record, and as such that needs to be handled.  eg:
+ *
+ * Existing record in the extent map:
+ *
+ *      cpos = 10, len = 10
+ *      |---------|
+ *
+ * New Record:
+ *
+ *      cpos = 10, len = 20
+ *      |------------------|
+ *
+ * The passed record is the new on-disk record.  The new_clusters value
+ * is how many clusters were added to the file.  If the append is a
+ * contiguous append, the new_clusters has been added to
+ * rec->e_clusters.  If the append is an entirely new extent, then
+ * rec->e_clusters is == new_clusters.
+ */
+int ocfs2_extent_map_append(struct inode *inode,
+                            struct ocfs2_extent_rec *rec,
+                            u32 new_clusters)
+{
+        int ret;
+        struct ocfs2_extent_map *em = &OCFS2_I(inode)->ip_map;
+        struct ocfs2_extent_map_entry *ent;
+        struct ocfs2_extent_rec *old;
+
+        BUG_ON(!new_clusters);
+        BUG_ON(le32_to_cpu(rec->e_clusters) < new_clusters);
+
+        if (em->em_clusters < OCFS2_I(inode)->ip_clusters) {
+                /*
+                 * Size changed underneath us on disk.  Drop any
+                 * straddling records and update our idea of
+                 * i_clusters
+                 */
+                ocfs2_extent_map_drop(inode, em->em_clusters - 1);
+                em->em_clusters = OCFS2_I(inode)->ip_clusters;
+        }
+
+        mlog_bug_on_msg((le32_to_cpu(rec->e_cpos) +
+                         le32_to_cpu(rec->e_clusters)) !=
+                        (em->em_clusters + new_clusters),
+                        "Inode %"MLFu64":\n"
+                        "rec->e_cpos = %u + rec->e_clusters = %u = %u\n"
+                        "em->em_clusters = %u + new_clusters = %u = %u\n",
+                        OCFS2_I(inode)->ip_blkno,
+                        le32_to_cpu(rec->e_cpos), le32_to_cpu(rec->e_clusters),
+                        le32_to_cpu(rec->e_cpos) + le32_to_cpu(rec->e_clusters),
+                        em->em_clusters, new_clusters,
+                        em->em_clusters + new_clusters);
+
+        em->em_clusters += new_clusters;
+
+        ret = -ENOENT;
+        if (le32_to_cpu(rec->e_clusters) > new_clusters) {
+                /* This is a contiguous append */
+                ent = ocfs2_extent_map_lookup(em, le32_to_cpu(rec->e_cpos), 1,
+                                              NULL, NULL);
+                if (ent) {
+                        old = &ent->e_rec;
+                        BUG_ON((le32_to_cpu(rec->e_cpos) +
+                                le32_to_cpu(rec->e_clusters)) !=
+                                 (le32_to_cpu(old->e_cpos) +
+                                  le32_to_cpu(old->e_clusters) +
+                                  new_clusters));
+                        if (ent->e_tree_depth == 0) {
+                                BUG_ON(le32_to_cpu(old->e_cpos) !=
+                                       le32_to_cpu(rec->e_cpos));
+                                BUG_ON(le64_to_cpu(old->e_blkno) !=
+                                       le64_to_cpu(rec->e_blkno));
+                                ret = 0;
+                        }
+                        /*
+                         * Let non-leafs fall through as -ENOENT to
+                         * force insertion of the new leaf.
+                         */
+                        le32_add_cpu(&old->e_clusters, new_clusters);
+                }
+        }
+
+        if (ret == -ENOENT)
+                ret = ocfs2_extent_map_insert(inode, rec, 0);
+        if (ret < 0)
+                mlog_errno(ret);
+        return ret;
+}
+
+#if 0
+/* Code here is included but defined out as it completes the extent
+ * map api and may be used in the future. */
+
+/*
+ * Look up the record containing this cluster offset.  This record is
+ * part of the extent map.  Do not free it.  Any changes you make to
+ * it will reflect in the extent map.  So, if your last extent
+ * is (cpos = 10, clusters = 10) and you truncate the file by 5
+ * clusters, you can do:
+ *
+ * ret = ocfs2_extent_map_get_rec(em, orig_size - 5, &rec);
+ * rec->e_clusters -= 5;
+ *
+ * The lookup does not read from disk.  If the map isn't filled in for
+ * an entry, you won't find it.
+ *
+ * Also note that the returned record is valid until alloc_sem is
+ * dropped.  After that, truncate and extend can happen.  Caveat Emptor.
+ */
+int ocfs2_extent_map_get_rec(struct inode *inode, u32 cpos,
+                             struct ocfs2_extent_rec **rec,
+                             int *tree_depth)
+{
+        int ret = -ENOENT;
+        struct ocfs2_extent_map *em = &OCFS2_I(inode)->ip_map;
+        struct ocfs2_extent_map_entry *ent;
+
+        *rec = NULL;
+
+        if (cpos >= OCFS2_I(inode)->ip_clusters)
+                return -EINVAL;
+
+        if (cpos >= em->em_clusters) {
+                /*
+                 * Size changed underneath us on disk.  Drop any
+                 * straddling records and update our idea of
+                 * i_clusters
+                 */
+                ocfs2_extent_map_drop(inode, em->em_clusters - 1);
+                em->em_clusters = OCFS2_I(inode)->ip_clusters ;
+        }
+
+        ent = ocfs2_extent_map_lookup(&OCFS2_I(inode)->ip_map, cpos, 1,
+                                      NULL, NULL);
+
+        if (ent) {
+                *rec = &ent->e_rec;
+                if (tree_depth)
+                        *tree_depth = ent->e_tree_depth;
+                ret = 0;
+        }
+
+        return ret;
+}
+
+int ocfs2_extent_map_get_clusters(struct inode *inode,
+                                  u32 v_cpos, int count,
+                                  u32 *p_cpos, int *ret_count)
+{
+        int ret;
+        u32 coff, ccount;
+        struct ocfs2_extent_map *em = &OCFS2_I(inode)->ip_map;
+        struct ocfs2_extent_map_entry *ent = NULL;
+
+        *p_cpos = ccount = 0;
+
+        if ((v_cpos + count) > OCFS2_I(inode)->ip_clusters)
+                return -EINVAL;
+
+        if ((v_cpos + count) > em->em_clusters) {
+                /*
+                 * Size changed underneath us on disk.  Drop any
+                 * straddling records and update our idea of
+                 * i_clusters
+                 */
+                ocfs2_extent_map_drop(inode, em->em_clusters - 1);
+                em->em_clusters = OCFS2_I(inode)->ip_clusters;
+        }
+
+
+        ret = ocfs2_extent_map_lookup_read(inode, v_cpos, count, &ent);
+        if (ret)
+                return ret;
+
+        if (ent) {
+                /* We should never find ourselves straddling an interval */
+                if (!ocfs2_extent_rec_contains_clusters(&ent->e_rec,
+                                                        v_cpos,
+                                                        count))
+                        return -ESRCH;
+
+                coff = v_cpos - le32_to_cpu(ent->e_rec.e_cpos);
+                *p_cpos = ocfs2_blocks_to_clusters(inode->i_sb,
+                                le64_to_cpu(ent->e_rec.e_blkno)) +
+                          coff;
+
+                if (ret_count)
+                        *ret_count = le32_to_cpu(ent->e_rec.e_clusters) - coff;
+
+                return 0;
+        }
+
+
+        return -ENOENT;
+}
+
+#endif  /*  0  */
+
+int ocfs2_extent_map_get_blocks(struct inode *inode,
+                                u64 v_blkno, int count,
+                                u64 *p_blkno, int *ret_count)
+{
+        int ret;
+        u64 boff;
+        u32 cpos, clusters;
+        int bpc = ocfs2_clusters_to_blocks(inode->i_sb, 1);
+        struct ocfs2_extent_map_entry *ent = NULL;
+        struct ocfs2_extent_map *em = &OCFS2_I(inode)->ip_map;
+        struct ocfs2_extent_rec *rec;
+
+        *p_blkno = 0;
+
+        cpos = ocfs2_blocks_to_clusters(inode->i_sb, v_blkno);
+        clusters = ocfs2_blocks_to_clusters(inode->i_sb,
+                                            (u64)count + bpc - 1);
+        if ((cpos + clusters) > OCFS2_I(inode)->ip_clusters) {
+                ret = -EINVAL;
+                mlog_errno(ret);
+                return ret;
+        }
+
+        if ((cpos + clusters) > em->em_clusters) {
+                /*
+                 * Size changed underneath us on disk.  Drop any
+                 * straddling records and update our idea of
+                 * i_clusters
+                 */
+                ocfs2_extent_map_drop(inode, em->em_clusters - 1);
+                em->em_clusters = OCFS2_I(inode)->ip_clusters;
+        }
+
+        ret = ocfs2_extent_map_lookup_read(inode, cpos, clusters, &ent);
+        if (ret) {
+                mlog_errno(ret);
+                return ret;
+        }
+
+        if (ent)
+        {
+                rec = &ent->e_rec;
+
+                /* We should never find ourselves straddling an interval */
+                if (!ocfs2_extent_rec_contains_clusters(rec, cpos, clusters)) {
+                        ret = -ESRCH;
+                        mlog_errno(ret);
+                        return ret;
+                }
+
+                boff = ocfs2_clusters_to_blocks(inode->i_sb, cpos -
+                                                le32_to_cpu(rec->e_cpos));
+                boff += (v_blkno & (u64)(bpc - 1));
+                *p_blkno = le64_to_cpu(rec->e_blkno) + boff;
+
+                if (ret_count) {
+                        *ret_count = ocfs2_clusters_to_blocks(inode->i_sb,
+                                        le32_to_cpu(rec->e_clusters)) - boff;
+                }
+
+                return 0;
+        }
+
+        return -ENOENT;
+}
+
+int ocfs2_extent_map_init(struct inode *inode)
+{
+        struct ocfs2_extent_map *em = &OCFS2_I(inode)->ip_map;
+
+        em->em_extents = RB_ROOT;
+        em->em_clusters = 0;
+
+        return 0;
+}
+
+/* Needs the lock */
+static void __ocfs2_extent_map_drop(struct inode *inode,
+                                    u32 new_clusters,
+                                    struct rb_node **free_head,
+                                    struct ocfs2_extent_map_entry **tail_ent)
+{
+        struct rb_node *node, *next;
+        struct ocfs2_extent_map *em = &OCFS2_I(inode)->ip_map;
+        struct ocfs2_extent_map_entry *ent;
+
+        *free_head = NULL;
+
+        ent = NULL;
+        node = rb_last(&em->em_extents);
+        while (node)
+        {
+                next = rb_prev(node);
+
+                ent = rb_entry(node, struct ocfs2_extent_map_entry,
+                               e_node);
+                if (le32_to_cpu(ent->e_rec.e_cpos) < new_clusters)
+                        break;
+
+                rb_erase(&ent->e_node, &em->em_extents);
+
+                node->rb_right = *free_head;
+                *free_head = node;
+
+                ent = NULL;
+                node = next;
+        }
+
+        /* Do we have an entry straddling new_clusters? */
+        if (tail_ent) {
+                if (ent &&
+                    ((le32_to_cpu(ent->e_rec.e_cpos) +
+                      le32_to_cpu(ent->e_rec.e_clusters)) > new_clusters))
+                        *tail_ent = ent;
+                else
+                        *tail_ent = NULL;
+        }
+}
+
+static void __ocfs2_extent_map_drop_cleanup(struct rb_node *free_head)
+{
+        struct rb_node *node;
+        struct ocfs2_extent_map_entry *ent;
+
+        while (free_head) {
+                node = free_head;
+                free_head = node->rb_right;
+
+                ent = rb_entry(node, struct ocfs2_extent_map_entry,
+                               e_node);
+                kmem_cache_free(ocfs2_em_ent_cachep, ent);
+        }
+}
+
+/*
+ * Remove all entries past new_clusters, inclusive of an entry that
+ * contains new_clusters.  This is effectively a cache forget.
+ *
+ * If you want to also clip the last extent by some number of clusters,
+ * you need to call ocfs2_extent_map_trunc().
+ * This code does not check or modify ip_clusters.
+ */
+int ocfs2_extent_map_drop(struct inode *inode, u32 new_clusters)
+{
+        struct rb_node *free_head = NULL;
+        struct ocfs2_extent_map *em = &OCFS2_I(inode)->ip_map;
+        struct ocfs2_extent_map_entry *ent;
+
+        spin_lock(&OCFS2_I(inode)->ip_lock);
+
+        __ocfs2_extent_map_drop(inode, new_clusters, &free_head, &ent);
+
+        if (ent) {
+                rb_erase(&ent->e_node, &em->em_extents);
+                ent->e_node.rb_right = free_head;
+                free_head = &ent->e_node;
+        }
+
+        spin_unlock(&OCFS2_I(inode)->ip_lock);
+
+        if (free_head)
+                __ocfs2_extent_map_drop_cleanup(free_head);
+
+        return 0;
+}
+
+/*
+ * Remove all entries past new_clusters and also clip any extent
+ * straddling new_clusters, if there is one.  This does not check
+ * or modify ip_clusters
+ */
+int ocfs2_extent_map_trunc(struct inode *inode, u32 new_clusters)
+{
+        struct rb_node *free_head = NULL;
+        struct ocfs2_extent_map_entry *ent = NULL;
+
+        spin_lock(&OCFS2_I(inode)->ip_lock);
+
+        __ocfs2_extent_map_drop(inode, new_clusters, &free_head, &ent);
+
+        if (ent)
+                ent->e_rec.e_clusters = cpu_to_le32(new_clusters -
+                                               le32_to_cpu(ent->e_rec.e_cpos));
+
+        OCFS2_I(inode)->ip_map.em_clusters = new_clusters;
+
+        spin_unlock(&OCFS2_I(inode)->ip_lock);
+
+        if (free_head)
+                __ocfs2_extent_map_drop_cleanup(free_head);
+
+        return 0;
+}
+
+int __init init_ocfs2_extent_maps(void)
+{
+        ocfs2_em_ent_cachep =
+                kmem_cache_create("ocfs2_em_ent",
+                                  sizeof(struct ocfs2_extent_map_entry),
+                                  0, SLAB_HWCACHE_ALIGN, NULL, NULL);
+        if (!ocfs2_em_ent_cachep)
+                return -ENOMEM;
+
+        return 0;
+}
+
+void __exit exit_ocfs2_extent_maps(void)
+{
+        kmem_cache_destroy(ocfs2_em_ent_cachep);
+}