f2fs: atomic: fix to truncate pagecache before on-disk metadata truncation

We should always truncate pagecache while truncating on-disk data.

Fixes: a46bebd5 ("f2fs: synchronize atomic write aborts")
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -2195,6 +2195,10 @@ static int f2fs_ioc_start_atomic_write(struct file *filp, bool truncate)
 		F2FS_I(fi->cow_inode)->atomic_inode = inode;
 	} else {
 		/* Reuse the already created COW inode */
+		f2fs_bug_on(sbi, get_dirty_pages(fi->cow_inode));
+
+		invalidate_mapping_pages(fi->cow_inode->i_mapping, 0, -1);
+
 		ret = f2fs_do_truncate_blocks(fi->cow_inode, 0, true);
 		if (ret) {
 			f2fs_up_write(&fi->i_gc_rwsem[WRITE]);