[PATCH 1/5] block: add a ->free_disk method

From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
	Jason Wang <jasowang@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	Maxim Levitsky <maximlevitsky@gmail.com>,
	Alex Dubov <oakad@yahoo.com>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	linux-block@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	linux-mmc@vger.kernel.org
Subject: [PATCH 1/5] block: add a ->free_disk method
Date: Wed,  9 Feb 2022 09:21:16 +0100	[thread overview]
Message-ID: <20220209082121.2628452-2-hch@lst.de> (raw)
In-Reply-To: <20220209082121.2628452-1-hch@lst.de>

Add a method to notify the driver that the gendisk is about to be freed.
This allows drivers to tie the lifetime of their private data to that of
the gendisk and thus deal with device removal races without expensive
synchronization and boilerplate code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 block/genhd.c          | 4 ++++
 include/linux/blkdev.h | 1 +
 2 files changed, 5 insertions(+)

diff --git a/block/genhd.c b/block/genhd.c
index 9589d1d59afab..1a650c55d7626 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1119,6 +1119,10 @@ static void disk_release(struct device *dev)
 	xa_destroy(&disk->part_tbl);
 	disk->queue->disk = NULL;
 	blk_put_queue(disk->queue);
+
+	if (disk->fops->free_disk)
+		disk->fops->free_disk(disk);
+
 	iput(disk->part0->bd_inode);	/* frees the disk */
 }
 
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 3bfc75a2a4509..a8f8aa4671037 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1464,6 +1464,7 @@ struct block_device_operations {
 	void (*unlock_native_capacity) (struct gendisk *);
 	int (*getgeo)(struct block_device *, struct hd_geometry *);
 	int (*set_read_only)(struct block_device *bdev, bool ro);
+	void (*free_disk)(struct gendisk *disk);
 	/* this callback is with swap_lock and sometimes page table lock held */
 	void (*swap_slot_free_notify) (struct block_device *, unsigned long);
 	int (*report_zones)(struct gendisk *, sector_t sector,
-- 
2.30.2

