Re: [PATCH] 2 of 2 - Allow O_EXCL on a block device to claim exclusive use.

[Christoph Hellwig <hch@infradead.org>]

On Mon, Aug 11, 2003 at 12:35:57PM +1000, NeilBrown wrote:
> diff ./fs/block_dev.c~current~ ./fs/block_dev.c
> --- ./fs/block_dev.c~current~	2003-08-11 09:01:38.000000000 +1000
> +++ ./fs/block_dev.c	2003-08-11 09:01:41.000000000 +1000
> @@ -643,6 +643,7 @@ int blkdev_get(struct block_device *bdev
>  int blkdev_open(struct inode * inode, struct file * filp)
>  {
>  	struct block_device *bdev;
> +	int res;
>  
>  	/*
>  	 * Preserve backwards compatibility and allow large file access
> @@ -655,7 +656,18 @@ int blkdev_open(struct inode * inode, st
>  	bd_acquire(inode);
>  	bdev = inode->i_bdev;
>  
> -	return do_open(bdev, inode, filp);
> +	res = do_open(bdev, inode, filp);
> +	if (res)
> +		return res;
> +
> +	if (!(filp->f_flags & O_EXCL) )
> +		return 0;
> +
> +	if (!(res = bd_claim(bdev, filp)))
> +		return 0;
> +
> +	blkdev_put(bdev, BDEV_FILE);
> +	return res;

Shouldn't you claim it before opening.  Also what is the desired
behaviour when opening partitions vs whole device with O_EXCL?