[PATCH RFC 1/3] Move codes related with submitting discard bio into one function

[Xiao Ni <xni@redhat.com>]

These codes can be used in raid10. So we can move these codes into md.c. raid0 and raid10
can share these codes.

Signed-off-by: Xiao Ni <xni@redhat.com>
---
 drivers/md/md.c    | 22 ++++++++++++++++++++++
 drivers/md/md.h    |  3 +++
 drivers/md/raid0.c | 15 ++-------------
 3 files changed, 27 insertions(+), 13 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 07e5b67..2b8f654 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8559,6 +8559,28 @@ void md_write_end(struct mddev *mddev)
 
 EXPORT_SYMBOL(md_write_end);
 
+void md_submit_discard_bio(struct mddev *mddev, struct md_rdev *rdev,
+				struct bio *bio,
+				sector_t dev_start, sector_t dev_end)
+{
+	struct bio *discard_bio = NULL;
+
+	if (__blkdev_issue_discard(rdev->bdev,
+	    dev_start + rdev->data_offset,
+	    dev_end - dev_start, GFP_NOIO, 0, &discard_bio) ||
+	    !discard_bio)
+		return;
+
+	bio_chain(discard_bio, bio);
+	bio_clone_blkg_association(discard_bio, bio);
+	if (mddev->gendisk)
+		trace_block_bio_remap(bdev_get_queue(rdev->bdev),
+			discard_bio, disk_devt(mddev->gendisk),
+			bio->bi_iter.bi_sector);
+	submit_bio_noacct(discard_bio);
+}
+EXPORT_SYMBOL(md_submit_discard_bio);
+
 /* md_allow_write(mddev)
  * Calling this ensures that the array is marked 'active' so that writes
  * may proceed without blocking.  It is important to call this before
diff --git a/drivers/md/md.h b/drivers/md/md.h
index c26fa8b..83ae77e 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -710,6 +710,9 @@ extern void md_write_end(struct mddev *mddev);
 extern void md_done_sync(struct mddev *mddev, int blocks, int ok);
 extern void md_error(struct mddev *mddev, struct md_rdev *rdev);
 extern void md_finish_reshape(struct mddev *mddev);
+extern void md_submit_discard_bio(struct mddev *mddev, struct md_rdev *rdev,
+				struct bio *bio,
+				sector_t dev_start, sector_t dev_end);
 
 extern int mddev_congested(struct mddev *mddev, int bits);
 extern bool __must_check md_flush_request(struct mddev *mddev, struct bio *bio);
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index e9e91c8..e37fe8a 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -525,7 +525,6 @@ static void raid0_handle_discard(struct mddev *mddev, struct bio *bio)
 
 	for (disk = 0; disk < zone->nb_dev; disk++) {
 		sector_t dev_start, dev_end;
-		struct bio *discard_bio = NULL;
 		struct md_rdev *rdev;
 
 		if (disk < start_disk_index)
@@ -548,18 +547,8 @@ static void raid0_handle_discard(struct mddev *mddev, struct bio *bio)
 
 		rdev = conf->devlist[(zone - conf->strip_zone) *
 			conf->strip_zone[0].nb_dev + disk];
-		if (__blkdev_issue_discard(rdev->bdev,
-			dev_start + zone->dev_start + rdev->data_offset,
-			dev_end - dev_start, GFP_NOIO, 0, &discard_bio) ||
-		    !discard_bio)
-			continue;
-		bio_chain(discard_bio, bio);
-		bio_clone_blkg_association(discard_bio, bio);
-		if (mddev->gendisk)
-			trace_block_bio_remap(bdev_get_queue(rdev->bdev),
-				discard_bio, disk_devt(mddev->gendisk),
-				bio->bi_iter.bi_sector);
-		submit_bio_noacct(discard_bio);
+		dev_start += zone->dev_start;
+		md_submit_discard_bio(mddev, rdev, bio, dev_start, dev_end);
 	}
 	bio_endio(bio);
 }
-- 
2.7.5