Index: linux-2.6.18-128.1.6/fs/ext4/mballoc.c
===================================================================
--- linux-2.6.18-128.1.6.orig/fs/ext4/mballoc.c	2009-05-29 16:32:19.000000000 +0530
+++ linux-2.6.18-128.1.6/fs/ext4/mballoc.c	2009-05-29 16:34:16.000000000 +0530
@@ -2949,14 +2949,20 @@
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
 	struct proc_dir_entry *proc;
 	struct proc_dir_entry *proc_entry;
-	char devname[64];
+	char devname[BDEVNAME_SIZE], *p;
 
 	if (proc_root_ext4 == NULL) {
 		sbi->s_mb_proc = NULL;
 		return -EINVAL;
 	}
 	bdevname(sb->s_bdev, devname);
+	p = devname;
+	while ((p = strchr(p, '/')))
+		*p = '!';
+
 	sbi->s_mb_proc = proc_mkdir(devname, proc_root_ext4);
+	if (!sbi->s_mb_proc)
+		goto err_create_dir;
 
 	MB_PROC_HANDLER(EXT4_MB_STATS_NAME, stats);
 	MB_PROC_HANDLER(EXT4_MB_MAX_TO_SCAN_NAME, max_to_scan);
@@ -2980,7 +2986,6 @@
 	return 0;
 
 err_out:
-	printk(KERN_ERR "EXT4-fs: Unable to create %s\n", devname);
 	remove_proc_entry(EXT4_MB_GROUP_PREALLOC, sbi->s_mb_proc);
 	remove_proc_entry(EXT4_MB_PREALLOC_TABLE, sbi->s_mb_proc);
 	remove_proc_entry(EXT4_MB_LARGE_REQ, sbi->s_mb_proc);
@@ -2993,18 +2998,23 @@
 	remove_proc_entry(devname, proc_root_ext4);
 	sbi->s_mb_proc = NULL;
 
+err_create_dir:
+	printk(KERN_ERR "EXT4-fs: Unable to create %s\n", devname);
 	return -ENOMEM;
 }
 
 static int ext4_mb_destroy_per_dev_proc(struct super_block *sb)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
-	char devname[64];
+	char devname[BDEVNAME_SIZE], *p;
 
 	if (sbi->s_mb_proc == NULL)
 		return -EINVAL;
 
 	bdevname(sb->s_bdev, devname);
+	p = devname;
+	while ((p = strchr(p, '/')))
+		*p = '!';
 	remove_proc_entry(EXT4_MB_GROUP_PREALLOC, sbi->s_mb_proc);
 	remove_proc_entry(EXT4_MB_PREALLOC_TABLE, sbi->s_mb_proc);
 	remove_proc_entry(EXT4_MB_LARGE_REQ, sbi->s_mb_proc);