Re: [PATCH v4 1/2] block: Add run_todo() operation

[Bart Van Assche <bvanassche@acm.org>]

On 9/21/26 10:08 PM, Tetsuo Handa wrote:
> I think post_release() is misleading because post_release() is also called
> when disk->fops->open() in blkdev_get_whole() failed (and therefore
> bdev->bd_disk->fops->release() in blkdev_put_whole() from blkdev_get_whole()
> was not called).

Has it been considered to call the new callback only if fops->release()
has been invoked? Here is an (untested) example of how this could be
implemented:

diff --git a/block/bdev.c b/block/bdev.c
index cd8323083740..82be4812a7a0 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -766,7 +766,8 @@ static void blkdev_put_whole(struct block_device *bdev)
  		bdev->bd_disk->fops->release(bdev->bd_disk);
  }

-static int blkdev_get_whole(struct block_device *bdev, blk_mode_t mode)
+static int blkdev_get_whole(struct block_device *bdev, blk_mode_t mode,
+			    bool *called_release)
  {
  	struct gendisk *disk = bdev->bd_disk;
  	int ret;
@@ -793,18 +794,20 @@ static int blkdev_get_whole(struct block_device 
*bdev, blk_mode_t mode)
  		ret = bdev_disk_changed(disk, false);
  		if (ret && (mode & BLK_OPEN_STRICT_SCAN)) {
  			blkdev_put_whole(bdev);
+			*called_release = true;
  			return ret;
  		}
  	}
  	return 0;
  }

-static int blkdev_get_part(struct block_device *part, blk_mode_t mode)
+static int blkdev_get_part(struct block_device *part, blk_mode_t mode,
+			   bool *called_release)
  {
  	struct gendisk *disk = part->bd_disk;
  	int ret;

-	ret = blkdev_get_whole(bdev_whole(part), mode);
+	ret = blkdev_get_whole(bdev_whole(part), mode, called_release);
  	if (ret)
  		return ret;

@@ -821,6 +824,7 @@ static int blkdev_get_part(struct block_device 
*part, blk_mode_t mode)

  out_blkdev_put:
  	blkdev_put_whole(bdev_whole(part));
+	*called_release = true;
  	return ret;
  }

@@ -973,6 +977,7 @@ int bdev_open(struct block_device *bdev, blk_mode_t 
mode, void *holder,
  {
  	bool unblock_events = true;
  	struct gendisk *disk = bdev->bd_disk;
+	bool called_release = false;
  	int ret;

  	if (holder) {
@@ -997,9 +1002,9 @@ int bdev_open(struct block_device *bdev, blk_mode_t 
mode, void *holder,
  	if (!bdev_may_open(bdev, mode))
  		goto put_module;
  	if (bdev_is_partition(bdev))
-		ret = blkdev_get_part(bdev, mode);
+		ret = blkdev_get_part(bdev, mode, &called_release);
  	else
-		ret = blkdev_get_whole(bdev, mode);
+		ret = blkdev_get_whole(bdev, mode, &called_release);
  	if (ret)
  		goto put_module;
  	bdev_claim_write_access(bdev, mode);
@@ -1037,7 +1042,14 @@ int bdev_open(struct block_device *bdev, 
blk_mode_t mode, void *holder,

  	return 0;
  put_module:
+	if (holder)
+		bd_abort_claiming(bdev, holder);
+	mutex_unlock(&disk->open_mutex);
+	if (called_release && disk->fops->post_release)
+		disk->fops->post_release(disk);
+	disk_unblock_events(disk);
  	module_put(disk->fops->owner);
+	return ret;
  abort_claiming:
  	if (holder)
  		bd_abort_claiming(bdev, holder);
@@ -1189,6 +1201,9 @@ void bdev_release(struct file *bdev_file)
  		blkdev_put_whole(bdev);
  	mutex_unlock(&disk->open_mutex);

+	if (disk->fops->post_release)
+		disk->fops->post_release(disk);
+
  	module_put(disk->fops->owner);
  put_no_open:
  	blkdev_put_no_open(bdev);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 4f7905c3412b..f2a2f70a9582 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1577,6 +1577,7 @@ struct block_device_operations {
  			unsigned int flags);
  	int (*open)(struct gendisk *disk, blk_mode_t mode);
  	void (*release)(struct gendisk *disk);
+	void (*post_release)(struct gendisk *disk);
  	int (*ioctl)(struct block_device *bdev, blk_mode_t mode,
  			unsigned cmd, unsigned long arg);
  	int (*compat_ioctl)(struct block_device *bdev, blk_mode_t mode,

Thanks,

Bart.