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 <[email protected]>
Reviewed-by: Zhang Yi <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Theodore Ts'o <[email protected]>

Author: Kemeng Shi

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;