10 files changed, 518 insertions, 7 deletions

diff --git a/fs/ocfs2/Makefile b/fs/ocfs2/Makefile
index d2057e7fbda7..3591890b32c6 100644
--- a/fs/ocfs2/Makefile
+++ b/fs/ocfs2/Makefile
@@ -21,6 +21,7 @@ ocfs2-objs := \
         localalloc.o            \
         mmap.o                  \
         namei.o                 \
+        resize.o                \
         slot_map.o              \
         suballoc.o              \
         super.o                 \
diff --git a/fs/ocfs2/buffer_head_io.c b/fs/ocfs2/buffer_head_io.c
index c9037414f4f6..31aa61dc777b 100644
--- a/fs/ocfs2/buffer_head_io.c
+++ b/fs/ocfs2/buffer_head_io.c
@@ -280,3 +280,64 @@ bail:
         mlog_exit(status);
         return status;
 }
+
+/* Check whether the blkno is the super block or one of the backups. */
+static void ocfs2_check_super_or_backup(struct super_block *sb,
+                                        sector_t blkno)
+{
+        int i;
+        u64 backup_blkno;
+
+        if (blkno == OCFS2_SUPER_BLOCK_BLKNO)
+                return;
+
+        for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) {
+                backup_blkno = ocfs2_backup_super_blkno(sb, i);
+                if (backup_blkno == blkno)
+                        return;
+        }
+
+        BUG();
+}
+
+/*
+ * Write super block and backups doesn't need to collaborate with journal,
+ * so we don't need to lock ip_io_mutex and inode doesn't need to bea passed
+ * into this function.
+ */
+int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
+                                struct buffer_head *bh)
+{
+        int ret = 0;
+
+        mlog_entry_void();
+
+        BUG_ON(buffer_jbd(bh));
+        ocfs2_check_super_or_backup(osb->sb, bh->b_blocknr);
+
+        if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb)) {
+                ret = -EROFS;
+                goto out;
+        }
+
+        lock_buffer(bh);
+        set_buffer_uptodate(bh);
+
+        /* remove from dirty list before I/O. */
+        clear_buffer_dirty(bh);
+
+        get_bh(bh); /* for end_buffer_write_sync() */
+        bh->b_end_io = end_buffer_write_sync;
+        submit_bh(WRITE, bh);
+
+        wait_on_buffer(bh);
+
+        if (!buffer_uptodate(bh)) {
+                ret = -EIO;
+                brelse(bh);
+        }
+
+out:
+        mlog_exit(ret);
+        return ret;
+}
diff --git a/fs/ocfs2/buffer_head_io.h b/fs/ocfs2/buffer_head_io.h
index 6cc20930fac3..c2e78614c3e5 100644
--- a/fs/ocfs2/buffer_head_io.h
+++ b/fs/ocfs2/buffer_head_io.h
@@ -47,6 +47,8 @@ int ocfs2_read_blocks(struct ocfs2_super          *osb,
                       int                  flags,
                       struct inode        *inode);
 
+int ocfs2_write_super_or_backup(struct ocfs2_super *osb,
+                                struct buffer_head *bh);
 
 #define OCFS2_BH_CACHED            1
 #define OCFS2_BH_READAHEAD         8
diff --git a/fs/ocfs2/ioctl.c b/fs/ocfs2/ioctl.c
index 67c2fb4bae91..b74b24ecf0e4 100644
--- a/fs/ocfs2/ioctl.c
+++ b/fs/ocfs2/ioctl.c
@@ -20,6 +20,7 @@
 
 #include "ocfs2_fs.h"
 #include "ioctl.h"
+#include "resize.h"
 
 #include <linux/ext2_fs.h>
 
@@ -115,6 +116,7 @@ int ocfs2_ioctl(struct inode * inode, struct file * filp,
         unsigned int cmd, unsigned long arg)
 {
         unsigned int flags;
+        int new_clusters;
         int status;
         struct ocfs2_space_resv sr;
 
@@ -140,6 +142,11 @@ int ocfs2_ioctl(struct inode * inode, struct file * filp,
                         return -EFAULT;
 
                 return ocfs2_change_file_space(filp, cmd, &sr);
+        case OCFS2_IOC_GROUP_EXTEND:
+                if (get_user(new_clusters, (int __user *)arg))
+                        return -EFAULT;
+
+                return ocfs2_group_extend(inode, new_clusters);
         default:
                 return -ENOTTY;
         }
@@ -162,6 +169,7 @@ long ocfs2_compat_ioctl(struct file *file, unsigned cmd, unsigned long arg)
         case OCFS2_IOC_RESVSP64:
         case OCFS2_IOC_UNRESVSP:
         case OCFS2_IOC_UNRESVSP64:
+        case OCFS2_IOC_GROUP_EXTEND:
                 break;
         default:
                 return -ENOIOCTLCMD;
diff --git a/fs/ocfs2/journal.h b/fs/ocfs2/journal.h
index 4b32e0961568..0ba3a421ccf2 100644
--- a/fs/ocfs2/journal.h
+++ b/fs/ocfs2/journal.h
@@ -278,6 +278,9 @@ int                  ocfs2_journal_dirty_data(handle_t *handle,
 /* simple file updates like chmod, etc. */
 #define OCFS2_INODE_UPDATE_CREDITS 1
 
+/* group extend. inode update and last group update. */
+#define OCFS2_GROUP_EXTEND_CREDITS      (OCFS2_INODE_UPDATE_CREDITS + 1)
+
 /* get one bit out of a suballocator: dinode + group descriptor +
  * prev. group desc. if we relink. */
 #define OCFS2_SUBALLOC_ALLOC (3)
diff --git a/fs/ocfs2/ocfs2_fs.h b/fs/ocfs2/ocfs2_fs.h
index 6ef876759a73..19ac421b613b 100644
--- a/fs/ocfs2/ocfs2_fs.h
+++ b/fs/ocfs2/ocfs2_fs.h
@@ -231,6 +231,8 @@ struct ocfs2_space_resv {
 #define OCFS2_IOC_RESVSP64      _IOW ('X', 42, struct ocfs2_space_resv)
 #define OCFS2_IOC_UNRESVSP64    _IOW ('X', 43, struct ocfs2_space_resv)
 
+#define OCFS2_IOC_GROUP_EXTEND  _IOW('o', 1, int)
+
 /*
  * Journal Flags (ocfs2_dinode.id1.journal1.i_flags)
  */
diff --git a/fs/ocfs2/resize.c b/fs/ocfs2/resize.c
new file mode 100644
index 000000000000..848f7293f4fc
--- /dev/null
+++ b/fs/ocfs2/resize.c
@@ -0,0 +1,398 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * resize.c
+ *
+ * volume resize.
+ * Inspired by ext3/resize.c.
+ *
+ * Copyright (C) 2007 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 as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * 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/types.h>
+
+#define MLOG_MASK_PREFIX ML_DISK_ALLOC
+#include <cluster/masklog.h>
+
+#include "ocfs2.h"
+
+#include "alloc.h"
+#include "dlmglue.h"
+#include "inode.h"
+#include "journal.h"
+#include "super.h"
+#include "sysfile.h"
+#include "uptodate.h"
+
+#include "buffer_head_io.h"
+#include "suballoc.h"
+#include "resize.h"
+
+/*
+ * Check whether there are new backup superblocks exist
+ * in the last group. If there are some, mark them or clear
+ * them in the bitmap.
+ *
+ * Return how many backups we find in the last group.
+ */
+static u16 ocfs2_calc_new_backup_super(struct inode *inode,
+                                       struct ocfs2_group_desc *gd,
+                                       int new_clusters,
+                                       u32 first_new_cluster,
+                                       u16 cl_cpg,
+                                       int set)
+{
+        int i;
+        u16 backups = 0;
+        u32 cluster;
+        u64 blkno, gd_blkno, lgd_blkno = le64_to_cpu(gd->bg_blkno);
+
+        for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) {
+                blkno = ocfs2_backup_super_blkno(inode->i_sb, i);
+                cluster = ocfs2_blocks_to_clusters(inode->i_sb, blkno);
+
+                gd_blkno = ocfs2_which_cluster_group(inode, cluster);
+                if (gd_blkno < lgd_blkno)
+                        continue;
+                else if (gd_blkno > lgd_blkno)
+                        break;
+
+                if (set)
+                        ocfs2_set_bit(cluster % cl_cpg,
+                                      (unsigned long *)gd->bg_bitmap);
+                else
+                        ocfs2_clear_bit(cluster % cl_cpg,
+                                        (unsigned long *)gd->bg_bitmap);
+                backups++;
+        }
+
+        mlog_exit_void();
+        return backups;
+}
+
+static int ocfs2_update_last_group_and_inode(handle_t *handle,
+                                             struct inode *bm_inode,
+                                             struct buffer_head *bm_bh,
+                                             struct buffer_head *group_bh,
+                                             u32 first_new_cluster,
+                                             int new_clusters)
+{
+        int ret = 0;
+        struct ocfs2_super *osb = OCFS2_SB(bm_inode->i_sb);
+        struct ocfs2_dinode *fe = (struct ocfs2_dinode *) bm_bh->b_data;
+        struct ocfs2_chain_list *cl = &fe->id2.i_chain;
+        struct ocfs2_chain_rec *cr;
+        struct ocfs2_group_desc *group;
+        u16 chain, num_bits, backups = 0;
+        u16 cl_bpc = le16_to_cpu(cl->cl_bpc);
+        u16 cl_cpg = le16_to_cpu(cl->cl_cpg);
+
+        mlog_entry("(new_clusters=%d, first_new_cluster = %u)\n",
+                   new_clusters, first_new_cluster);
+
+        ret = ocfs2_journal_access(handle, bm_inode, group_bh,
+                                   OCFS2_JOURNAL_ACCESS_WRITE);
+        if (ret < 0) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        group = (struct ocfs2_group_desc *)group_bh->b_data;
+
+        /* update the group first. */
+        num_bits = new_clusters * cl_bpc;
+        le16_add_cpu(&group->bg_bits, num_bits);
+        le16_add_cpu(&group->bg_free_bits_count, num_bits);
+
+        /*
+         * check whether there are some new backup superblocks exist in
+         * this group and update the group bitmap accordingly.
+         */
+        if (OCFS2_HAS_COMPAT_FEATURE(osb->sb,
+                                     OCFS2_FEATURE_COMPAT_BACKUP_SB)) {
+                backups = ocfs2_calc_new_backup_super(bm_inode,
+                                                     group,
+                                                     new_clusters,
+                                                     first_new_cluster,
+                                                     cl_cpg, 1);
+                le16_add_cpu(&group->bg_free_bits_count, -1 * backups);
+        }
+
+        ret = ocfs2_journal_dirty(handle, group_bh);
+        if (ret < 0) {
+                mlog_errno(ret);
+                goto out_rollback;
+        }
+
+        /* update the inode accordingly. */
+        ret = ocfs2_journal_access(handle, bm_inode, bm_bh,
+                                   OCFS2_JOURNAL_ACCESS_WRITE);
+        if (ret < 0) {
+                mlog_errno(ret);
+                goto out_rollback;
+        }
+
+        chain = le16_to_cpu(group->bg_chain);
+        cr = (&cl->cl_recs[chain]);
+        le32_add_cpu(&cr->c_total, num_bits);
+        le32_add_cpu(&cr->c_free, num_bits);
+        le32_add_cpu(&fe->id1.bitmap1.i_total, num_bits);
+        le32_add_cpu(&fe->i_clusters, new_clusters);
+
+        if (backups) {
+                le32_add_cpu(&cr->c_free, -1 * backups);
+                le32_add_cpu(&fe->id1.bitmap1.i_used, backups);
+        }
+
+        spin_lock(&OCFS2_I(bm_inode)->ip_lock);
+        OCFS2_I(bm_inode)->ip_clusters = le32_to_cpu(fe->i_clusters);
+        le64_add_cpu(&fe->i_size, new_clusters << osb->s_clustersize_bits);
+        spin_unlock(&OCFS2_I(bm_inode)->ip_lock);
+        i_size_write(bm_inode, le64_to_cpu(fe->i_size));
+
+        ocfs2_journal_dirty(handle, bm_bh);
+
+out_rollback:
+        if (ret < 0) {
+                ocfs2_calc_new_backup_super(bm_inode,
+                                            group,
+                                            new_clusters,
+                                            first_new_cluster,
+                                            cl_cpg, 0);
+                le16_add_cpu(&group->bg_free_bits_count, backups);
+                le16_add_cpu(&group->bg_bits, -1 * num_bits);
+                le16_add_cpu(&group->bg_free_bits_count, -1 * num_bits);
+        }
+out:
+        mlog_exit(ret);
+        return ret;
+}
+
+static int update_backups(struct inode * inode, u32 clusters, char *data)
+{
+        int i, ret = 0;
+        u32 cluster;
+        u64 blkno;
+        struct buffer_head *backup = NULL;
+        struct ocfs2_dinode *backup_di = NULL;
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+        /* calculate the real backups we need to update. */
+        for (i = 0; i < OCFS2_MAX_BACKUP_SUPERBLOCKS; i++) {
+                blkno = ocfs2_backup_super_blkno(inode->i_sb, i);
+                cluster = ocfs2_blocks_to_clusters(inode->i_sb, blkno);
+                if (cluster > clusters)
+                        break;
+
+                ret = ocfs2_read_block(osb, blkno, &backup, 0, NULL);
+                if (ret < 0) {
+                        mlog_errno(ret);
+                        break;
+                }
+
+                memcpy(backup->b_data, data, inode->i_sb->s_blocksize);
+
+                backup_di = (struct ocfs2_dinode *)backup->b_data;
+                backup_di->i_blkno = cpu_to_le64(blkno);
+
+                ret = ocfs2_write_super_or_backup(osb, backup);
+                brelse(backup);
+                backup = NULL;
+                if (ret < 0) {
+                        mlog_errno(ret);
+                        break;
+                }
+        }
+
+        return ret;
+}
+
+static void ocfs2_update_super_and_backups(struct inode *inode,
+                                           int new_clusters)
+{
+        int ret;
+        u32 clusters = 0;
+        struct buffer_head *super_bh = NULL;
+        struct ocfs2_dinode *super_di = NULL;
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+
+        /*
+         * update the superblock last.
+         * It doesn't matter if the write failed.
+         */
+        ret = ocfs2_read_block(osb, OCFS2_SUPER_BLOCK_BLKNO,
+                               &super_bh, 0, NULL);
+        if (ret < 0) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        super_di = (struct ocfs2_dinode *)super_bh->b_data;
+        le32_add_cpu(&super_di->i_clusters, new_clusters);
+        clusters = le32_to_cpu(super_di->i_clusters);
+
+        ret = ocfs2_write_super_or_backup(osb, super_bh);
+        if (ret < 0) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        if (OCFS2_HAS_COMPAT_FEATURE(osb->sb, OCFS2_FEATURE_COMPAT_BACKUP_SB))
+                ret = update_backups(inode, clusters, super_bh->b_data);
+
+out:
+        if (super_bh)
+                brelse(super_bh);
+        if (ret)
+                printk(KERN_WARNING "ocfs2: Failed to update super blocks on %s"
+                        " during fs resize. This condition is not fatal,"
+                        " but fsck.ocfs2 should be run to fix it\n",
+                        osb->dev_str);
+        return;
+}
+
+/*
+ * Extend the filesystem to the new number of clusters specified.  This entry
+ * point is only used to extend the current filesystem to the end of the last
+ * existing group.
+ */
+int ocfs2_group_extend(struct inode * inode, int new_clusters)
+{
+        int ret;
+        handle_t *handle;
+        struct buffer_head *main_bm_bh = NULL;
+        struct buffer_head *group_bh = NULL;
+        struct inode *main_bm_inode = NULL;
+        struct ocfs2_dinode *fe = NULL;
+        struct ocfs2_group_desc *group = NULL;
+        struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
+        u16 cl_bpc;
+        u32 first_new_cluster;
+        u64 lgd_blkno;
+
+        mlog_entry_void();
+
+        if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb))
+                return -EROFS;
+
+        if (new_clusters < 0)
+                return -EINVAL;
+        else if (new_clusters == 0)
+                return 0;
+
+        main_bm_inode = ocfs2_get_system_file_inode(osb,
+                                                    GLOBAL_BITMAP_SYSTEM_INODE,
+                                                    OCFS2_INVALID_SLOT);
+        if (!main_bm_inode) {
+                ret = -EINVAL;
+                mlog_errno(ret);
+                goto out;
+        }
+
+        mutex_lock(&main_bm_inode->i_mutex);
+
+        ret = ocfs2_inode_lock(main_bm_inode, &main_bm_bh, 1);
+        if (ret < 0) {
+                mlog_errno(ret);
+                goto out_mutex;
+        }
+
+        fe = (struct ocfs2_dinode *)main_bm_bh->b_data;
+
+        if (le16_to_cpu(fe->id2.i_chain.cl_cpg) !=
+                                 ocfs2_group_bitmap_size(osb->sb) * 8) {
+                mlog(ML_ERROR, "The disk is too old and small. "
+                     "Force to do offline resize.");
+                ret = -EINVAL;
+                goto out_unlock;
+        }
+
+        if (!OCFS2_IS_VALID_DINODE(fe)) {
+                OCFS2_RO_ON_INVALID_DINODE(main_bm_inode->i_sb, fe);
+                ret = -EIO;
+                goto out_unlock;
+        }
+
+        first_new_cluster = le32_to_cpu(fe->i_clusters);
+        lgd_blkno = ocfs2_which_cluster_group(main_bm_inode,
+                                              first_new_cluster - 1);
+
+        ret = ocfs2_read_block(osb, lgd_blkno, &group_bh, OCFS2_BH_CACHED,
+                               main_bm_inode);
+        if (ret < 0) {
+                mlog_errno(ret);
+                goto out_unlock;
+        }
+
+        group = (struct ocfs2_group_desc *)group_bh->b_data;
+
+        ret = ocfs2_check_group_descriptor(inode->i_sb, fe, group);
+        if (ret) {
+                mlog_errno(ret);
+                goto out_unlock;
+        }
+
+        cl_bpc = le16_to_cpu(fe->id2.i_chain.cl_bpc);
+        if (le16_to_cpu(group->bg_bits) / cl_bpc + new_clusters >
+                le16_to_cpu(fe->id2.i_chain.cl_cpg)) {
+                ret = -EINVAL;
+                goto out_unlock;
+        }
+
+        mlog(0, "extend the last group at %llu, new clusters = %d\n",
+             le64_to_cpu(group->bg_blkno), new_clusters);
+
+        handle = ocfs2_start_trans(osb, OCFS2_GROUP_EXTEND_CREDITS);
+        if (IS_ERR(handle)) {
+                mlog_errno(PTR_ERR(handle));
+                ret = -EINVAL;
+                goto out_unlock;
+        }
+
+        /* update the last group descriptor and inode. */
+        ret = ocfs2_update_last_group_and_inode(handle, main_bm_inode,
+                                                main_bm_bh, group_bh,
+                                                first_new_cluster,
+                                                new_clusters);
+        if (ret) {
+                mlog_errno(ret);
+                goto out_commit;
+        }
+
+        ocfs2_update_super_and_backups(main_bm_inode, new_clusters);
+
+out_commit:
+        ocfs2_commit_trans(osb, handle);
+out_unlock:
+        if (group_bh)
+                brelse(group_bh);
+
+        if (main_bm_bh)
+                brelse(main_bm_bh);
+
+        ocfs2_inode_unlock(main_bm_inode, 1);
+
+out_mutex:
+        mutex_unlock(&main_bm_inode->i_mutex);
+        iput(main_bm_inode);
+
+out:
+        mlog_exit_void();
+        return ret;
+}
diff --git a/fs/ocfs2/resize.h b/fs/ocfs2/resize.h
new file mode 100644
index 000000000000..3acb79af451b
--- /dev/null
+++ b/fs/ocfs2/resize.h
@@ -0,0 +1,31 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * resize.h
+ *
+ * Function prototypes
+ *
+ * Copyright (C) 2007 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 as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * 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.
+ */
+
+#ifndef OCFS2_RESIZE_H
+#define OCFS2_RESIZE_H
+
+int ocfs2_group_extend(struct inode * inode, int new_clusters);
+
+#endif /* OCFS2_RESIZE_H */
diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
index 6df4dbf67d18..4391744e80f8 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -101,8 +101,6 @@ static inline int ocfs2_block_group_reasonably_empty(struct ocfs2_group_desc *bg
 static inline u32 ocfs2_desc_bitmap_to_cluster_off(struct inode *inode,
                                                    u64 bg_blkno,
                                                    u16 bg_bit_off);
-static inline u64 ocfs2_which_cluster_group(struct inode *inode,
-                                            u32 cluster);
 static inline void ocfs2_block_to_cluster_group(struct inode *inode,
                                                 u64 data_blkno,
                                                 u64 *bg_blkno,
@@ -131,9 +129,9 @@ static u32 ocfs2_bits_per_group(struct ocfs2_chain_list *cl)
 }
 
 /* somewhat more expensive than our other checks, so use sparingly. */
-static int ocfs2_check_group_descriptor(struct super_block *sb,
-                                        struct ocfs2_dinode *di,
-                                        struct ocfs2_group_desc *gd)
+int ocfs2_check_group_descriptor(struct super_block *sb,
+                                 struct ocfs2_dinode *di,
+                                 struct ocfs2_group_desc *gd)
 {
         unsigned int max_bits;
 
@@ -1443,8 +1441,7 @@ static inline u32 ocfs2_desc_bitmap_to_cluster_off(struct inode *inode,
 
 /* given a cluster offset, calculate which block group it belongs to
  * and return that block offset. */
-static inline u64 ocfs2_which_cluster_group(struct inode *inode,
-                                            u32 cluster)
+u64 ocfs2_which_cluster_group(struct inode *inode, u32 cluster)
 {
         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
         u32 group_no;
diff --git a/fs/ocfs2/suballoc.h b/fs/ocfs2/suballoc.h
index cafe93703095..8799033bb459 100644
--- a/fs/ocfs2/suballoc.h
+++ b/fs/ocfs2/suballoc.h
@@ -147,4 +147,12 @@ static inline int ocfs2_is_cluster_bitmap(struct inode *inode)
 int ocfs2_reserve_cluster_bitmap_bits(struct ocfs2_super *osb,
                                       struct ocfs2_alloc_context *ac);
 
+/* given a cluster offset, calculate which block group it belongs to
+ * and return that block offset. */
+u64 ocfs2_which_cluster_group(struct inode *inode, u32 cluster);
+
+/* somewhat more expensive than our other checks, so use sparingly. */
+int ocfs2_check_group_descriptor(struct super_block *sb,
+                                 struct ocfs2_dinode *di,
+                                 struct ocfs2_group_desc *gd);
 #endif /* _CHAINALLOC_H_ */