2 files changed, 38 insertions, 19 deletions

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index a52a8191bb91..6a3b36d5bad6 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1070,45 +1070,60 @@ static ssize_t reset_store(struct device *dev,
 	struct zram *zram;
 	struct block_device *bdev;
 
+	ret = kstrtou16(buf, 10, &do_reset);
+	if (ret)
+		return ret;
+
+	if (!do_reset)
+		return -EINVAL;
+
 	zram = dev_to_zram(dev);
 	bdev = bdget_disk(zram->disk, 0);
-
 	if (!bdev)
 		return -ENOMEM;
 
 	mutex_lock(&bdev->bd_mutex);
-	/* Do not reset an active device! */
-	if (bdev->bd_openers) {
-		ret = -EBUSY;
-		goto out;
+	/* Do not reset an active device or claimed device */
+	if (bdev->bd_openers || zram->claim) {
+		mutex_unlock(&bdev->bd_mutex);
+		bdput(bdev);
+		return -EBUSY;
 	}
 
-	ret = kstrtou16(buf, 10, &do_reset);
-	if (ret)
-		goto out;
-
-	if (!do_reset) {
-		ret = -EINVAL;
-		goto out;
-	}
+	/* From now on, anyone can't open /dev/zram[0-9] */
+	zram->claim = true;
+	mutex_unlock(&bdev->bd_mutex);
 
-	/* Make sure all pending I/O is finished */
+	/* Make sure all the pending I/O are finished */
 	fsync_bdev(bdev);
 	zram_reset_device(zram);
-
-	mutex_unlock(&bdev->bd_mutex);
 	revalidate_disk(zram->disk);
 	bdput(bdev);
 
+	mutex_lock(&bdev->bd_mutex);
+	zram->claim = false;
+	mutex_unlock(&bdev->bd_mutex);
+
 	return len;
+}
+
+static int zram_open(struct block_device *bdev, fmode_t mode)
+{
+	int ret = 0;
+	struct zram *zram;
+
+	WARN_ON(!mutex_is_locked(&bdev->bd_mutex));
+
+	zram = bdev->bd_disk->private_data;
+	/* zram was claimed to reset so open request fails */
+	if (zram->claim)
+		ret = -EBUSY;
 
-out:
-	mutex_unlock(&bdev->bd_mutex);
-	bdput(bdev);
 	return ret;
 }
 
 static const struct block_device_operations zram_devops = {
+	.open = zram_open,
 	.swap_slot_free_notify = zram_slot_free_notify,
 	.rw_page = zram_rw_page,
 	.owner = THIS_MODULE
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 042994e807cf..6dbe2df506bf 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -115,5 +115,9 @@ struct zram {
 	 */
 	u64 disksize;	/* bytes */
 	char compressor[10];
+	/*
+	 * zram is claimed so open request will be failed
+	 */
+	bool claim; /* Protected by bdev->bd_mutex */
 };
 #endif