On Thu 24-08-23 11:42:50, Qi Zheng wrote:
> In preparation for implementing lockless slab shrink, use new APIs to
> dynamically allocate the jbd2-journal shrinker, so that it can be freed
> asynchronously via RCU. Then it doesn't need to wait for RCU read-side
> critical section when releasing the struct journal_s.
>
> Signed-off-by: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
> Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> CC: "Theodore Ts'o" <tytso@xxxxxxx>
> CC: Jan Kara <jack@xxxxxxxx>
> CC: linux-ext4@xxxxxxxxxxxxxxx
Looks good to me. Feel free to add:
Acked-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> fs/jbd2/journal.c | 30 +++++++++++++++++++-----------
> include/linux/jbd2.h | 2 +-
> 2 files changed, 20 insertions(+), 12 deletions(-)
>
> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
> index 768fa05bcbed..75692baa76e8 100644
> --- a/fs/jbd2/journal.c
> +++ b/fs/jbd2/journal.c
> @@ -1290,7 +1290,7 @@ static int jbd2_min_tag_size(void)
> static unsigned long jbd2_journal_shrink_scan(struct shrinker *shrink,
> struct shrink_control *sc)
> {
> - journal_t *journal = container_of(shrink, journal_t, j_shrinker);
> + journal_t *journal = shrink->private_data;
> unsigned long nr_to_scan = sc->nr_to_scan;
> unsigned long nr_shrunk;
> unsigned long count;
> @@ -1316,7 +1316,7 @@ static unsigned long jbd2_journal_shrink_scan(struct shrinker *shrink,
> static unsigned long jbd2_journal_shrink_count(struct shrinker *shrink,
> struct shrink_control *sc)
> {
> - journal_t *journal = container_of(shrink, journal_t, j_shrinker);
> + journal_t *journal = shrink->private_data;
> unsigned long count;
>
> count = percpu_counter_read_positive(&journal->j_checkpoint_jh_count);
> @@ -1588,14 +1588,22 @@ static journal_t *journal_init_common(struct block_device *bdev,
> goto err_cleanup;
>
> journal->j_shrink_transaction = NULL;
> - journal->j_shrinker.scan_objects = jbd2_journal_shrink_scan;
> - journal->j_shrinker.count_objects = jbd2_journal_shrink_count;
> - journal->j_shrinker.seeks = DEFAULT_SEEKS;
> - journal->j_shrinker.batch = journal->j_max_transaction_buffers;
> - err = register_shrinker(&journal->j_shrinker, "jbd2-journal:(%u:%u)",
> - MAJOR(bdev->bd_dev), MINOR(bdev->bd_dev));
> - if (err)
> +
> + journal->j_shrinker = shrinker_alloc(0, "jbd2-journal:(%u:%u)",
> + MAJOR(bdev->bd_dev),
> + MINOR(bdev->bd_dev));
> + if (!journal->j_shrinker) {
> + err = -ENOMEM;
> goto err_cleanup;
> + }
> +
> + journal->j_shrinker->scan_objects = jbd2_journal_shrink_scan;
> + journal->j_shrinker->count_objects = jbd2_journal_shrink_count;
> + journal->j_shrinker->seeks = DEFAULT_SEEKS;
> + journal->j_shrinker->batch = journal->j_max_transaction_buffers;
> + journal->j_shrinker->private_data = journal;
> +
> + shrinker_register(journal->j_shrinker);
>
> return journal;
>
> @@ -2170,9 +2178,9 @@ int jbd2_journal_destroy(journal_t *journal)
> brelse(journal->j_sb_buffer);
> }
>
> - if (journal->j_shrinker.flags & SHRINKER_REGISTERED) {
> + if (journal->j_shrinker) {
> percpu_counter_destroy(&journal->j_checkpoint_jh_count);
> - unregister_shrinker(&journal->j_shrinker);
> + shrinker_free(journal->j_shrinker);
> }
> if (journal->j_proc_entry)
> jbd2_stats_proc_exit(journal);
> diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
> index 52772c826c86..6dcbb4eb80fb 100644
> --- a/include/linux/jbd2.h
> +++ b/include/linux/jbd2.h
> @@ -886,7 +886,7 @@ struct journal_s
> * Journal head shrinker, reclaim buffer's journal head which
> * has been written back.
> */
> - struct shrinker j_shrinker;
> + struct shrinker *j_shrinker;
>
> /**
> * @j_checkpoint_jh_count:
> --
> 2.30.2
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
