f2fs: introduce max_file_blocks in sbi

Introduce max_file_blocks in sbi to store max block index of file in f2fs,
it could be used to avoid unneeded calculation of max block index in
runtime.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
[Jaegeuk Kim: fix overflow of sbi->max_file_blocks]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index e2990c9..882baba 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -783,6 +783,7 @@
 	unsigned int total_node_count;		/* total node block count */
 	unsigned int total_valid_node_count;	/* valid node block count */
 	unsigned int total_valid_inode_count;	/* valid inode count */
+	loff_t max_file_blocks;			/* max block index of file */
 	int active_logs;			/* # of active logs */
 	int dir_level;				/* directory level */
 
@@ -1727,7 +1728,6 @@
  * super.c
  */
 int f2fs_commit_super(struct f2fs_sb_info *, bool);
-loff_t max_file_size(unsigned bits);
 int f2fs_sync_fs(struct super_block *, int);
 extern __printf(3, 4)
 void f2fs_msg(struct super_block *, const char *, const char *, ...);