jbd2: remove unneeded kmap for jh_in->b_frozen_data in jbd2_journal_write_metadata_buffer

Remove kmap for page of b_frozen_data from jbd2_alloc() which always
provides an address from the direct kernel mapping.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20240801013815.2393869-5-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 51f184ba830c2122502964842df98722732e671e..f7464ac29cd5c21245a3d34ccc286febd3550bd6 100644 (file)
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -352,12 +352,13 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
                done_copy_out = 1;
                new_folio = virt_to_folio(jh_in->b_frozen_data);
                new_offset = offset_in_folio(new_folio, jh_in->b_frozen_data);
+               mapped_data = jh_in->b_frozen_data;
        } else {
                new_folio = bh_in->b_folio;
                new_offset = offset_in_folio(new_folio, bh_in->b_data);
+               mapped_data = kmap_local_folio(new_folio, new_offset);
        }
 
-       mapped_data = kmap_local_folio(new_folio, new_offset);
        /*
         * Fire data frozen trigger if data already wasn't frozen.  Do this
         * before checking for escaping, as the trigger may modify the magic
@@ -373,7 +374,8 @@ int jbd2_journal_write_metadata_buffer(transaction_t *transaction,
         */
        if (*((__be32 *)mapped_data) == cpu_to_be32(JBD2_MAGIC_NUMBER))
                do_escape = 1;
-       kunmap_local(mapped_data);
+       if (!jh_in->b_frozen_data)
+               kunmap_local(mapped_data);
 
        /*
         * Do we need to do a data copy?