linux-kernel - [PATCH v4 03/11] md/md-bitmap: support discard for bitmap ops

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Message-ID: <20250721171557.34587-4-yukuai@kernel.org>
Date: Tue, 22 Jul 2025 01:15:49 +0800
From: Yu Kuai <yukuai@...nel.org>
To: corbet@....net,
	agk@...hat.co,
	snitzer@...nel.org,
	mpatocka@...hat.com,
	hch@....de,
	song@...nel.org,
	hare@...e.de
Cc: linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	dm-devel@...ts.linux.dev,
	linux-raid@...r.kernel.org,
	yukuai3@...wei.com,
	yangerkun@...wei.com,
	yi.zhang@...wei.com,
	johnny.chenyi@...wei.com,
	Xiao Ni <xni@...hat.com>
Subject: [PATCH v4 03/11] md/md-bitmap: support discard for bitmap ops

From: Yu Kuai <yukuai3@...wei.com>

Use two new methods {start, end}_discard in bitmap_ops and a new field 'rw'
in struct md_io_clone to handle discard IO, prepare to support new md
bitmap.

Since all bitmap functions to hanlde write IO are the same, also add
typedef to make code cleaner.

Signed-off-by: Yu Kuai <yukuai3@...wei.com>
Reviewed-by: Xiao Ni <xni@...hat.com>
Reviewed-by: Hannes Reinecke <hare@...e.de>
---
 drivers/md/md-bitmap.c |  3 +++
 drivers/md/md-bitmap.h | 12 ++++++++----
 drivers/md/md.c        | 15 +++++++++++----
 drivers/md/md.h        |  1 +
 4 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index 3c8b8ecf0695..0eb3774f372d 100644
--- a/drivers/md/md-bitmap.c
+++ b/drivers/md/md-bitmap.c
@@ -3006,6 +3006,9 @@ static struct bitmap_operations bitmap_ops = {
 
 	.start_write		= bitmap_start_write,
 	.end_write		= bitmap_end_write,
+	.start_discard		= bitmap_start_write,
+	.end_discard		= bitmap_end_write,
+
 	.start_sync		= bitmap_start_sync,
 	.end_sync		= bitmap_end_sync,
 	.cond_end_sync		= bitmap_cond_end_sync,
diff --git a/drivers/md/md-bitmap.h b/drivers/md/md-bitmap.h
index 42f91755a341..8616ced49077 100644
--- a/drivers/md/md-bitmap.h
+++ b/drivers/md/md-bitmap.h
@@ -61,6 +61,9 @@ struct md_bitmap_stats {
 	struct file	*file;
 };
 
+typedef void (md_bitmap_fn)(struct mddev *mddev, sector_t offset,
+			    unsigned long sectors);
+
 struct bitmap_operations {
 	struct md_submodule_head head;
 
@@ -81,10 +84,11 @@ struct bitmap_operations {
 	void (*end_behind_write)(struct mddev *mddev);
 	void (*wait_behind_writes)(struct mddev *mddev);
 
-	void (*start_write)(struct mddev *mddev, sector_t offset,
-			    unsigned long sectors);
-	void (*end_write)(struct mddev *mddev, sector_t offset,
-			  unsigned long sectors);
+	md_bitmap_fn *start_write;
+	md_bitmap_fn *end_write;
+	md_bitmap_fn *start_discard;
+	md_bitmap_fn *end_discard;
+
 	bool (*start_sync)(struct mddev *mddev, sector_t offset,
 			   sector_t *blocks, bool degraded);
 	void (*end_sync)(struct mddev *mddev, sector_t offset, sector_t *blocks);
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 1db7af64184d..efb38b9cfbd0 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8858,18 +8858,24 @@ EXPORT_SYMBOL_GPL(md_submit_discard_bio);
 static void md_bitmap_start(struct mddev *mddev,
 			    struct md_io_clone *md_io_clone)
 {
+	md_bitmap_fn *fn = unlikely(md_io_clone->rw == STAT_DISCARD) ?
+			   mddev->bitmap_ops->start_discard :
+			   mddev->bitmap_ops->start_write;
+
 	if (mddev->pers->bitmap_sector)
 		mddev->pers->bitmap_sector(mddev, &md_io_clone->offset,
 					   &md_io_clone->sectors);
 
-	mddev->bitmap_ops->start_write(mddev, md_io_clone->offset,
-				       md_io_clone->sectors);
+	fn(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->end_write(mddev, md_io_clone->offset,
-				     md_io_clone->sectors);
+	md_bitmap_fn *fn = unlikely(md_io_clone->rw == STAT_DISCARD) ?
+			   mddev->bitmap_ops->end_discard :
+			   mddev->bitmap_ops->end_write;
+
+	fn(mddev, md_io_clone->offset, md_io_clone->sectors);
 }
 
 static void md_end_clone_io(struct bio *bio)
@@ -8908,6 +8914,7 @@ static void md_clone_bio(struct mddev *mddev, struct bio **bio)
 	if (bio_data_dir(*bio) == WRITE && md_bitmap_enabled(mddev, false)) {
 		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 72bce59376d7..8452aaa2295d 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -872,6 +872,7 @@ struct md_io_clone {
 	unsigned long	start_time;
 	sector_t	offset;
 	unsigned long	sectors;
+	enum stat_group	rw;
 	struct bio	bio_clone;
 };
 
-- 
2.43.0