diff -rupN linux-2.6.18-164.6.1_1//fs/ext4/ialloc.c linux-2.6.18-164.6.1_2//fs/ext4/ialloc.c
--- linux-2.6.18-164.6.1_1//fs/ext4/ialloc.c	2010-03-31 17:42:50.000000000 +0530
+++ linux-2.6.18-164.6.1_2//fs/ext4/ialloc.c	2010-03-31 17:43:22.000000000 +0530
@@ -710,12 +710,15 @@ struct inode *ext4_new_inode_goal(handle
 	sb = dir->i_sb;
 	trace_mark(ext4_request_inode, "dev %s dir %lu mode %d", sb->s_id,
 		   dir->i_ino, mode);
+	sbi = EXT4_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 = EXT4_I(inode);
 
-	sbi = EXT4_SB(sb);
 	es = sbi->s_es;
 
 	if (goal && goal <= le32_to_cpu(es->s_inodes_count)) {
diff -rupN linux-2.6.18-164.6.1_1//fs/ext4/super.c linux-2.6.18-164.6.1_2//fs/ext4/super.c
--- linux-2.6.18-164.6.1_1//fs/ext4/super.c	2010-03-31 17:42:50.000000000 +0530
+++ linux-2.6.18-164.6.1_2//fs/ext4/super.c	2010-03-31 17:45:32.000000000 +0530
@@ -40,6 +40,7 @@
 #include <asm/uaccess.h>
 #include <linux/kthread.h>
 #include <linux/utsname.h>
+#include <linux/proc_fs.h>
 
 #include "ext4.h"
 #include "ext4_jbd2.h"
@@ -581,6 +582,7 @@ static void ext4_put_super(struct super_
 		ext4_commit_super(sb, es, 1);
 	}
 	if (sbi->s_proc) {
+		remove_proc_entry(EXT4_MAX_DIR_SIZE_NAME, sbi->s_proc);
 		remove_proc_entry("inode_readahead_blks", sbi->s_proc);
 		remove_proc_entry("inode_goal", sbi->s_proc);
 		remove_proc_entry(sb->s_id, ext4_proc_root);
@@ -2341,6 +2343,48 @@ static unsigned long ext4_get_stripe_siz
 	return 0;
 }
 
+#ifdef CONFIG_PROC_FS
+static int ext4_max_dir_size_read(char *page, char **start, off_t off,
+                                  int count, int *eof, void *data)
+{
+	struct ext4_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 ext4_max_dir_size_write(struct file *file, const char *buffer,
+                                   unsigned long count, void *data)
+{
+	struct ext4_sb_info *sbi = data;
+	char str[32];
+	unsigned long value;
+	char *end;
+
+	if (count >= sizeof(str)) {
+		printk(KERN_ERR "EXT4-fs: %s string too long, max %u bytes\n",
+		       EXT4_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;
+}
+#endif
+
 static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 				__releases(kernel_lock)
 				__acquires(kernel_lock)
@@ -2690,6 +2734,19 @@ static int ext4_fill_super(struct super_
 			p->proc_fops = &ext4_ui_proc_fops,
 			p->data = &sbi->s_inode_goal;
 		}
+		sbi->s_max_dir_size = EXT4_DEFAULT_MAX_DIR_SIZE;
+		p = create_proc_entry(EXT4_MAX_DIR_SIZE_NAME,
+				      S_IFREG | S_IRUGO | S_IWUSR, sbi->s_proc);
+		if (p == NULL) {
+			printk(KERN_ERR "EXT4-fs: unable to create %s\n",
+			       EXT4_MAX_DIR_SIZE_NAME);
+			ret = -ENOMEM;
+			goto failed_mount;
+		}
+		p->data = sbi;
+		p->read_proc = ext4_max_dir_size_read;
+		p->write_proc = ext4_max_dir_size_write;
+
 	}
 #endif
 
@@ -2976,6 +3033,7 @@ failed_mount2:
 	kfree(sbi->s_group_desc);
 failed_mount:
 	if (sbi->s_proc) {
+		remove_proc_entry(EXT4_MAX_DIR_SIZE_NAME, sbi->s_proc);
 		remove_proc_entry("inode_readahead_blks", sbi->s_proc);
 		remove_proc_entry("inode_goal", sbi->s_proc);
 		remove_proc_entry(sb->s_id, ext4_proc_root);
diff -rupN linux-2.6.18-164.6.1_1//fs/ext4/ext4_sb.h linux-2.6.18-164.6.1_2//fs/ext4/ext4_sb.h
--- linux-2.6.18-164.6.1_1//fs/ext4/ext4_sb.h	2010-03-31 17:42:50.000000000 +0530
+++ linux-2.6.18-164.6.1_2//fs/ext4/ext4_sb.h	2010-03-31 17:43:22.000000000 +0530
@@ -119,6 +119,7 @@ struct ext4_sb_info {
 	/* where last allocation was done - for stream allocation */
 	unsigned long s_mb_last_group;
 	unsigned long s_mb_last_start;
+	unsigned long s_max_dir_size;
 
 	/* history to debug policy */
 	struct ext4_mb_history *s_mb_history;
diff -rupN linux-2.6.18-164.6.1_1//fs/ext4/ext4.h linux-2.6.18-164.6.1_2//fs/ext4/ext4.h
--- linux-2.6.18-164.6.1_1//fs/ext4/ext4.h	2010-03-31 17:42:50.000000000 +0530
+++ linux-2.6.18-164.6.1_2//fs/ext4/ext4.h	2010-03-31 17:43:22.000000000 +0530
@@ -1029,6 +1029,12 @@ struct mmp_struct {
 #define EXT4_MMP_MIN_CHECK_INTERVAL	5
 
 /*
+ * max directory size tunable
+ */
+#define EXT4_DEFAULT_MAX_DIR_SIZE	0
+#define EXT4_MAX_DIR_SIZE_NAME		"max_dir_size"
+
+/*
  * Function prototypes
  */