diff -pur linux-stage.orig/fs/ext3/ialloc.c linux-stage/fs/ext3/ialloc.c
--- linux-stage.orig/fs/ext3/ialloc.c	2008-06-01 16:18:53.000000000 +0800
+++ linux-stage/fs/ext3/ialloc.c	2008-06-03 02:21:02.000000000 +0800
@@ -519,12 +519,15 @@ struct inode *ext3_new_inode(handle_t *h
 		return ERR_PTR(-EPERM);
 
 	sb = dir->i_sb;
+	sbi = EXT3_SB(sb);
+	if (sbi->s_max_dir_size > 0 && i_size_read(dir) >= sbi->s_max_dir_size)
+		return ERR_PTR(-EFBIG);
+
 	inode = new_inode(sb);
 	if (!inode)
 		return ERR_PTR(-ENOMEM);
 	ei = EXT3_I(inode);
 
-	sbi = EXT3_SB(sb);
 	es = sbi->s_es;
 	if (goal) {
 		group = (goal - 1) / EXT3_INODES_PER_GROUP(sb);
diff -pur linux-stage.orig/fs/ext3/super.c linux-stage/fs/ext3/super.c
--- linux-stage.orig/fs/ext3/super.c	2008-06-03 01:53:34.000000000 +0800
+++ linux-stage/fs/ext3/super.c	2008-06-03 19:39:19.000000000 +0800
@@ -42,6 +42,12 @@
 #include "acl.h"
 #include "group.h"
 
+/*
+ * max directory size tunable
+ */
+#define EXT3_DEFAULT_MAX_DIR_SIZE		0
+#define EXT3_MAX_DIR_SIZE_NAME		"max_dir_size"
+
 static int ext3_load_journal(struct super_block *, struct ext3_super_block *,
 			     unsigned long journal_devnum);
 static int ext3_create_journal(struct super_block *, struct ext3_super_block *,
@@ -446,6 +452,7 @@ void ext3_put_super (struct super_block 
 	if (sbi->s_mmp_tsk)
 		kthread_stop(sbi->s_mmp_tsk);
 
+	remove_proc_entry(EXT3_MAX_DIR_SIZE_NAME, sbi->s_dev_proc);
 	remove_proc_entry(sb->s_id, proc_root_ext3);
 	sbi->s_dev_proc = NULL;
 	sb->s_fs_info = NULL;
@@ -1765,6 +1772,45 @@ failed:
 	return 1;
 }
 
+static int ext3_max_dir_size_read(char *page, char **start, off_t off,
+                                  int count, int *eof, void *data)
+{
+	struct ext3_sb_info *sbi = data;
+	int len;
+
+	*eof = 1;
+	if (off != 0)
+		return 0;
+
+	len = sprintf(page, "%lu\n", sbi->s_max_dir_size);
+	*start = page;
+	return len;
+}
+
+static int ext3_max_dir_size_write(struct file *file, const char *buffer,
+                                   unsigned long count, void *data)
+{
+	struct ext3_sb_info *sbi = data;
+	char str[32];
+	unsigned long value;
+	char *end;
+
+	if (count >= sizeof(str)) {
+		printk(KERN_ERR "EXT3-fs: %s string too long, max %u bytes\n",
+		       EXT3_MAX_DIR_SIZE_NAME, (int)sizeof(str));
+		return -EOVERFLOW;
+	}
+
+	if (copy_from_user(str, buffer, count))
+		return -EFAULT;
+
+	value = simple_strtol(str, &end, 0);
+	if (value < 0)
+		return -ERANGE;
+
+	sbi->s_max_dir_size = value;
+	return count;
+}
 
 static int ext3_fill_super (struct super_block *sb, void *data, int silent)
 {
@@ -1785,6 +1831,7 @@ static int ext3_fill_super (struct super
 	int i;
 	int needs_recovery;
 	__le32 features;
+	struct proc_dir_entry *proc;
 
 	sbi = kmalloc(sizeof(*sbi), GFP_KERNEL);
 	if (!sbi)
@@ -1802,6 +1849,23 @@ static int ext3_fill_super (struct super
 		return -ENOMEM;
 	}
 
+	sbi->s_max_dir_size = EXT3_DEFAULT_MAX_DIR_SIZE;
+	proc = create_proc_entry(EXT3_MAX_DIR_SIZE_NAME,
+		                 S_IFREG | S_IRUGO | S_IWUSR, sbi->s_dev_proc);
+	if (proc == NULL) {
+		printk(KERN_ERR "EXT3-fs: unable to create %s\n", 
+		       EXT3_MAX_DIR_SIZE_NAME);
+		remove_proc_entry(EXT3_MAX_DIR_SIZE_NAME, sbi->s_dev_proc);
+		remove_proc_entry(sb->s_id, proc_root_ext3);
+		sbi->s_dev_proc = NULL;
+		sb->s_fs_info = NULL;
+		kfree(sbi);
+		return -ENOMEM;
+	}
+	proc->data = sbi;
+	proc->read_proc = ext3_max_dir_size_read;
+	proc->write_proc = ext3_max_dir_size_write;
+
 	blocksize = sb_min_blocksize(sb, EXT3_MIN_BLOCK_SIZE);
 	if (!blocksize) {
 		printk(KERN_ERR "EXT3-fs: unable to set blocksize\n");
@@ -2224,6 +2288,7 @@ failed_mount:
 	ext3_blkdev_remove(sbi);
 	brelse(bh);
 out_fail:
+	remove_proc_entry(EXT3_MAX_DIR_SIZE_NAME, sbi->s_dev_proc);
 	remove_proc_entry(sb->s_id, proc_root_ext3);
 	sbi->s_dev_proc = NULL;
 	sb->s_fs_info = NULL;
diff -pur linux-stage.orig/include/linux/ext3_fs_sb.h linux-stage/include/linux/ext3_fs_sb.h
--- linux-stage.orig/include/linux/ext3_fs_sb.h	2008-06-01 16:18:54.000000000 +0800
+++ linux-stage/include/linux/ext3_fs_sb.h	2008-06-03 02:21:02.000000000 +0800
@@ -114,6 +114,7 @@ struct ext3_sb_info {
 	unsigned long s_mb_max_groups_to_scan;
 	unsigned long s_mb_stats;
 	unsigned long s_mb_order2_reqs;
+	unsigned long s_max_dir_size;
 
 	/* history to debug policy */
 	struct ext3_mb_history *s_mb_history;