[PATCH RFC md-6.16 v3 02/19] md: support discard for bitmap ops

[Yu Kuai]

From: Yu Kuai <yuku...@huawei.com>

If {start, end}_discard is implemented from bitmap_operations, then they
will be used to handle discard IO. Currently md-bitmap handle discard
the same as normal write, prepare to support discard for new md bitmap.

Signed-off-by: Yu Kuai <yuku...@huawei.com>
---
 drivers/md/md.c | 19 +++++++++++++++----
 drivers/md/md.h |  1 +
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 32b997dfe6f4..c72c13ed4253 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8849,14 +8849,24 @@ static void md_bitmap_start(struct mddev *mddev,
                mddev->pers->bitmap_sector(mddev, &md_io_clone->offset,
                                           &md_io_clone->sectors);
 
-       mddev->bitmap_ops->startwrite(mddev, md_io_clone->offset,
-                                     md_io_clone->sectors);
+       if (unlikely(md_io_clone->rw == STAT_DISCARD) &&
+           mddev->bitmap_ops->start_discard)
+               mddev->bitmap_ops->start_discard(mddev, md_io_clone->offset,
+                                                md_io_clone->sectors);
+       else
+               mddev->bitmap_ops->startwrite(mddev, md_io_clone->offset,
+                                             md_io_clone->sectors);
 }
 
 static void md_bitmap_end(struct mddev *mddev, struct md_io_clone *md_io_clone)
 {
-       mddev->bitmap_ops->endwrite(mddev, md_io_clone->offset,
-                                   md_io_clone->sectors);
+       if (unlikely(md_io_clone->rw == STAT_DISCARD) &&
+           mddev->bitmap_ops->end_discard)
+               mddev->bitmap_ops->end_discard(mddev, md_io_clone->offset,
+                                              md_io_clone->sectors);
+       else
+               mddev->bitmap_ops->endwrite(mddev, md_io_clone->offset,
+                                           md_io_clone->sectors);
 }
 
 static void md_end_clone_io(struct bio *bio)
@@ -8895,6 +8905,7 @@ static void md_clone_bio(struct mddev *mddev, struct bio 
**bio)
        if (bio_data_dir(*bio) == WRITE && md_bitmap_enabled(mddev)) {
                md_io_clone->offset = (*bio)->bi_iter.bi_sector;
                md_io_clone->sectors = bio_sectors(*bio);
+               md_io_clone->rw = op_stat_group(bio_op(*bio));
                md_bitmap_start(mddev, md_io_clone);
        }
 
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 6eb5dfdf2f55..c474bf74c345 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -850,6 +850,7 @@ struct md_io_clone {
        unsigned long   start_time;
        sector_t        offset;
        unsigned long   sectors;
+       enum stat_group rw;
        struct bio      bio_clone;
 };
 
-- 
2.39.2