f2fs: fix to wait dio completion

It should wait all existing dio write IOs before block removal,
otherwise, previous direct write IO may overwrite data in the
block which may be reused by other inode.

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

fs/f2fs/file.c

@@ -1055,6 +1055,13 @@ int f2fs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 				return err;
 		}
 
+		/*
+		 * wait for inflight dio, blocks should be removed after
+		 * IO completion.
+		 */
+		if (attr->ia_size < old_size)
+			inode_dio_wait(inode);
+
 		f2fs_down_write(&fi->i_gc_rwsem[WRITE]);
 		filemap_invalidate_lock(inode->i_mapping);
 
@@ -1891,6 +1898,12 @@ static long f2fs_fallocate(struct file *file, int mode,
 	if (ret)
 		goto out;
 
+	/*
+	 * wait for inflight dio, blocks should be removed after IO
+	 * completion.
+	 */
+	inode_dio_wait(inode);
+
 	if (mode & FALLOC_FL_PUNCH_HOLE) {
 		if (offset >= inode->i_size)
 			goto out;