jbd2: remove unneeded kmap to do escape in jbd2_journal_write_metadata_buffer

The data to do escape could be accessed directly from b_frozen_data,
just remove unneeded kmap.
Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20240514112438.1269037-6-shikemeng@huaweicloud.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/jbd2/journal.c

@@ -419,12 +419,11 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
 	/*
 	 * Did we need to do an escaping?  Now we've done all the
 	 * copying, we can finally do so.
+	 * b_frozen_data is from jbd2_alloc() which always provides an
+	 * address from the direct kernels mapping.
 	 */
-	if (do_escape) {
-		mapped_data = kmap_local_folio(new_folio, new_offset);
-		*((unsigned int *)mapped_data) = 0;
-		kunmap_local(mapped_data);
-	}
+	if (do_escape)
+		*((unsigned int *)jh_in->b_frozen_data) = 0;
 
 	folio_set_bh(new_bh, new_folio, new_offset);
 	new_bh->b_size = bh_in->b_size;