btrfs: use bio::remaining for async checksumming synchronization

We can use bio::remaining counter to sync the offloaded checksumming.
As a result we can slim down the btrfs_bio structure by 24 bytes
and simplify the code a bit.

Difference in pahole output:

-	/* size: 328, cachelines: 6, members: 15 */
+	/* size: 304, cachelines: 5, members: 14 */

Moreover this will allow us enabling async checksumming with encryption
where we need to checksum the bounce bio instead of our regular one
embedded in btrfs_bio. And so we need to extend it's lifetime. This is
the preferred way to do so.

This also fixes a bug in experimental build where the async checksumming
was using the system workqueue instead of fs_info::endio_workers.

Fixes: dd57c78aec39 ("btrfs: introduce btrfs_bio::async_csum")
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Daniel Vacek <neelx@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/bio.c b/fs/btrfs/bio.c
index 19b4855969f53611411b7fbdeb02a6c9cd082114..771b7d598aeeeb99b9cc9d190e4380bdaacdde20 100644 (file)
--- a/fs/btrfs/bio.c
+++ b/fs/btrfs/bio.c
@@ -103,7 +103,6 @@ static struct btrfs_bio *btrfs_split_bio(struct btrfs_fs_info *fs_info,
        bbio->can_use_append = orig_bbio->can_use_append;
        bbio->is_scrub = orig_bbio->is_scrub;
        bbio->is_remap = orig_bbio->is_remap;
-       bbio->async_csum = orig_bbio->async_csum;
 
        atomic_inc(&orig_bbio->pending_ios);
        return bbio;
@@ -114,9 +113,6 @@ void btrfs_bio_end_io(struct btrfs_bio *bbio, blk_status_t status)
        /* Make sure we're already in task context. */
        ASSERT(in_task());
 
-       if (bbio->async_csum)
-               wait_for_completion(&bbio->csum_done);
-
        bbio->bio.bi_status = status;
        if (bbio->bio.bi_pool == &btrfs_clone_bioset) {
                struct btrfs_bio *orig_bbio = bbio->private;

diff --git a/fs/btrfs/bio.h b/fs/btrfs/bio.h
index b7bd377a016249fab4709f1510d7b1d6805fe28c..bbf362b8668bbc51157bc4d3417fc9c607de355a 100644 (file)
--- a/fs/btrfs/bio.h
+++ b/fs/btrfs/bio.h
@@ -58,7 +58,6 @@ struct btrfs_bio {
                        struct btrfs_ordered_extent *ordered;
                        struct btrfs_ordered_sum *sums;
                        struct work_struct csum_work;
-                       struct completion csum_done;
                        struct bvec_iter csum_saved_iter;
                        u64 orig_physical;
                        u64 orig_logical;
@@ -93,9 +92,6 @@ struct btrfs_bio {
        /* Whether the bio is coming from copy_remapped_data_io(). */
        bool is_remap:1;
 
-       /* Whether the csum generation for data write is async. */
-       bool async_csum:1;
-
        /* Whether the bio is written using zone append. */
        bool can_use_append:1;
 

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 2c6c14dfe39320af6a7c590cb0948bbcd841168b..ae1fd4da38d31bf6155397067e8556974fa56cce 100644 (file)
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -819,9 +819,8 @@ static void csum_one_bio_work(struct work_struct *work)
        struct btrfs_bio *bbio = container_of(work, struct btrfs_bio, csum_work);
 
        ASSERT(btrfs_op(&bbio->bio) == BTRFS_MAP_WRITE);
-       ASSERT(bbio->async_csum == true);
        csum_one_bio(bbio);
-       complete(&bbio->csum_done);
+       bio_endio(&bbio->bio);
 }
 
 /*
@@ -855,10 +854,9 @@ int btrfs_csum_one_bio(struct btrfs_bio *bbio, bool async)
                csum_one_bio(bbio);
                return 0;
        }
-       init_completion(&bbio->csum_done);
-       bbio->async_csum = true;
+       bio_inc_remaining(bio);
        INIT_WORK(&bbio->csum_work, csum_one_bio_work);
-       schedule_work(&bbio->csum_work);
+       queue_work(fs_info->endio_workers, &bbio->csum_work);
        return 0;
 }