f2fs: let f2fs_precache_extents() traverses in file range

Rather than in range of [0, max_file_blocks()), since data after EOF
is alwasy zero, it's unnecessary to preload mapping info of the data.

Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Author: chaseyu

fs/f2fs/file.c

@@ -3263,7 +3263,7 @@ int f2fs_precache_extents(struct inode *inode)
 	map.m_next_extent = &m_next_extent;
 	map.m_seg_type = NO_CHECK_TYPE;
 	map.m_may_create = false;
-	end = max_file_blocks(inode);
+	end = F2FS_BLK_ALIGN(i_size_read(inode));
 
 	while (map.m_lblk < end) {
 		map.m_len = end - map.m_lblk;