Re: [dm-devel] [PATCH 4/8] block: support delayed holder registration

[Christoph Hellwig <hch@lst.de>]

Please try the patch below:

---
From 7609266da56160d211662cd2fbe26570aad11b15 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Fri, 20 Aug 2021 17:00:11 +0200
Subject: mtd_blkdevs: don't hold del_mtd_blktrans_dev in
 blktrans_{open,release}

There is nothing that this protects against except for slightly reducing
the window when new opens can appear just before calling del_gendisk.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/mtd/mtd_blkdevs.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index 44bea3f65060..6b81a1c9ccbe 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -207,7 +207,6 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode)
 	if (!dev)
 		return -ERESTARTSYS; /* FIXME: busy loop! -arnd*/
 
-	mutex_lock(&mtd_table_mutex);
 	mutex_lock(&dev->lock);
 
 	if (dev->open)
@@ -233,7 +232,6 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode)
 unlock:
 	dev->open++;
 	mutex_unlock(&dev->lock);
-	mutex_unlock(&mtd_table_mutex);
 	blktrans_dev_put(dev);
 	return ret;
 
@@ -244,7 +242,6 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode)
 	module_put(dev->tr->owner);
 	kref_put(&dev->ref, blktrans_dev_release);
 	mutex_unlock(&dev->lock);
-	mutex_unlock(&mtd_table_mutex);
 	blktrans_dev_put(dev);
 	return ret;
 }
@@ -256,7 +253,6 @@ static void blktrans_release(struct gendisk *disk, fmode_t mode)
 	if (!dev)
 		return;
 
-	mutex_lock(&mtd_table_mutex);
 	mutex_lock(&dev->lock);
 
 	if (--dev->open)
@@ -272,7 +268,6 @@ static void blktrans_release(struct gendisk *disk, fmode_t mode)
 	}
 unlock:
 	mutex_unlock(&dev->lock);
-	mutex_unlock(&mtd_table_mutex);
 	blktrans_dev_put(dev);
 }
 
-- 
2.30.2