f2fs: use percpu_counter for alloc_valid_block_count

This patch uses percpu_count for sbi->alloc_valid_block_count.

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 0ff862b..43e3e9c3 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -617,6 +617,7 @@
 
 	for (i = 0; i < NR_COUNT_TYPE; i++)
 		percpu_counter_destroy(&sbi->nr_pages[i]);
+	percpu_counter_destroy(&sbi->alloc_valid_block_count);
 }
 
 static void f2fs_put_super(struct super_block *sb)
@@ -1382,7 +1383,9 @@
 		if (err)
 			return err;
 	}
-	return 0;
+
+	return percpu_counter_init(&sbi->alloc_valid_block_count, 0,
+								GFP_KERNEL);
 }
 
 /*
@@ -1601,7 +1604,7 @@
 	sbi->total_valid_block_count =
 				le64_to_cpu(sbi->ckpt->valid_block_count);
 	sbi->last_valid_block_count = sbi->total_valid_block_count;
-	sbi->alloc_valid_block_count = 0;
+
 	for (i = 0; i < NR_INODE_TYPE; i++) {
 		INIT_LIST_HEAD(&sbi->inode_list[i]);
 		spin_lock_init(&sbi->inode_lock[i]);