[dm-devel] [PATCH 16/45] block: switch bdgrab to use igrab

[Hannes Reinecke]

On 11/28/20 5:14 PM, Christoph Hellwig wrote:
> All of the current callers already have a reference, but to prepare for
> additional users ensure bdgrab returns NULL if the block device is beeing
> freed.
> 
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> ---
>   fs/block_dev.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index d707ab376da86e..962fabe8a67b83 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -894,10 +894,14 @@ static struct block_device *bdget(dev_t dev)
>   /**
>    * bdgrab -- Grab a reference to an already referenced block device
>    * @bdev:	Block device to grab a reference to.
> + *
> + * Returns the block_device with an additional reference when successful,
> + * or NULL if the inode is already beeing freed.
>    */
>   struct block_device *bdgrab(struct block_device *bdev)
>   {
> -	ihold(bdev->bd_inode);
> +	if (!igrab(bdev->bd_inode))
> +		return NULL;
>   	return bdev;
>   }
>   EXPORT_SYMBOL(bdgrab);
> 
Reviewed-by: Hannes Reinecke <hare at suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare at suse.de                              +49 911 74053 688
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