2024-05-06 14:22:03

by Kemeng Shi

Subject: [PATCH 5/9] 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]>
---
fs/jbd2/journal.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 77fcdc76fdfd..87f558bd2e8a 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -423,11 +423,8 @@ 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.
*/
- 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;
--
2.30.0

2024-05-13 13:44:24

by Jan Kara

Subject: Re: [PATCH 5/9] jbd2: remove unneeded kmap to do escape in jbd2_journal_write_metadata_buffer

On Mon 06-05-24 22:17:57, Kemeng Shi wrote:
> The data to do escape could be accessed directly from b_frozen_data,
> just remove unneeded kmap.
>
> Signed-off-by: Kemeng Shi <[email protected]>

Ah, good point. But this deserves a comment at that site that jbd2_alloc()
always provides an address from the direct kernel mapping. Otherwise feel
free to add:

Reviewed-by: Jan Kara <[email protected]>

Honza

> ---
> fs/jbd2/journal.c | 7 ++-----
> 1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
> index 77fcdc76fdfd..87f558bd2e8a 100644
> --- a/fs/jbd2/journal.c
> +++ b/fs/jbd2/journal.c
> @@ -423,11 +423,8 @@ 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.
> */
> - 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;
> --
> 2.30.0
>
--
Jan Kara <[email protected]>
SUSE Labs, CR