ext4: Check that reservation counters are self-consistent.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 49d88c0..2b072c9 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -40,6 +40,7 @@
 #include <linux/log2.h>
 #include <linux/crc16.h>
 #include <asm/uaccess.h>
+#include <linux/stringify.h>
 
 #include "ext4.h"
 #include "ext4_jbd2.h"
@@ -640,6 +641,18 @@ static void dump_orphan_list(struct super_block *sb, struct ext4_sb_info *sbi)
 	}
 }
 
+#define CHECK_COUNTER(sb, counter, val)					\
+	do {								\
+		if (percpu_counter_sum_positive(&EXT4_SB(sb)->counter) != \
+			(s64)(val))					\
+			ext4_warning((sb), "Counter %s contain unexpected " \
+				"value %lld, expected %lld\n",		\
+				__stringify(counter),			\
+				percpu_counter_sum_positive(		\
+					&EXT4_SB(sb)->counter),		\
+				(s64)(val));				\
+	} while(0);
+
 static void ext4_put_super(struct super_block *sb)
 {
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
@@ -677,6 +690,11 @@ static void ext4_put_super(struct super_block *sb)
 	}
 	kobject_del(&sbi->s_kobj);
 
+	CHECK_COUNTER(sb, s_dirs_counter, ext4_count_dirs(sb));
+	CHECK_COUNTER(sb, s_dirtyblocks_counter, 0UL);
+	CHECK_COUNTER(sb, s_freeblocks_counter, ext4_count_free_blocks(sb));
+	CHECK_COUNTER(sb, s_freeinodes_counter, ext4_count_free_inodes(sb));
+
 	for (i = 0; i < sbi->s_gdb_count; i++)
 		brelse(sbi->s_group_desc[i]);
 	kfree(sbi->s_group_desc);
@@ -770,7 +788,7 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
 
 static void ext4_destroy_inode(struct inode *inode)
 {
-	if (!list_empty(&(EXT4_I(inode)->i_orphan))) {
+	if (unlikely(!list_empty(&(EXT4_I(inode)->i_orphan)))) {
 		ext4_msg(inode->i_sb, KERN_ERR,
 			 "Inode %lu (%p): orphan list check failed!",
 			 inode->i_ino, EXT4_I(inode));
@@ -779,6 +797,18 @@ static void ext4_destroy_inode(struct inode *inode)
 				true);
 		dump_stack();
 	}
+	if (unlikely(EXT4_I(inode)->i_reserved_data_blocks) ||
+		EXT4_I(inode)->i_reserved_meta_blocks ||
+		EXT4_I(inode)->i_allocated_meta_blocks)  {
+		ext4_msg(inode->i_sb, KERN_ERR, "Inode %lu (%p): Destroyed"
+			" inode still has reserved blocks and probably would"
+			" leak, rsv_data=%u, rsv_mdata=%u, alloc_mblk=%u",
+			inode->i_ino, EXT4_I(inode),
+			EXT4_I(inode)->i_reserved_data_blocks,
+			EXT4_I(inode)->i_reserved_meta_blocks,
+			EXT4_I(inode)->i_allocated_meta_blocks);
+		dump_stack();
+	}
 	kmem_cache_free(ext4_inode_cachep, EXT4_I(inode));
 }