[PATCH 30/31] block: store the holder in file->private_data

[Hannes Reinecke]

On 6/6/23 09:39, Christoph Hellwig wrote:
> Store the file struct used as the holder in file->private_data as an
> indicator that this file descriptor was opened exclusively to  remove
> the last use of FMODE_EXCL.
> 
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> ---
>   block/fops.c | 14 ++++++++------
>   1 file changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/block/fops.c b/block/fops.c
> index c40b9f978e3bc7..915e0ef7560993 100644
> --- a/block/fops.c
> +++ b/block/fops.c
> @@ -478,7 +478,7 @@ blk_mode_t file_to_blk_mode(struct file *file)
>   		mode |= BLK_OPEN_READ;
>   	if (file->f_mode & FMODE_WRITE)
>   		mode |= BLK_OPEN_WRITE;
> -	if (file->f_mode & FMODE_EXCL)
> +	if (file->private_data)
>   		mode |= BLK_OPEN_EXCL;
>   	if ((file->f_flags & O_ACCMODE) == 3)
>   		mode |= BLK_OPEN_WRITE_IOCTL;
> @@ -501,12 +501,15 @@ static int blkdev_open(struct inode *inode, struct file *filp)
>   	filp->f_flags |= O_LARGEFILE;
>   	filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC;
>   
> +	/*
> +	 * Use the file private data to store the holder, file_to_blk_mode
> +	 * relies on this.
> +	 */

Can you update the comment to reflect that we're only use the
->private_data field for exclusive open?
I know it's indicated by the condition, but we really should
be clarify this usage.

>   	if (filp->f_flags & O_EXCL)
> -		filp->f_mode |= FMODE_EXCL;
> +		filp->private_data = filp;
>   
>   	bdev = blkdev_get_by_dev(inode->i_rdev, file_to_blk_mode(filp),
> -				 (filp->f_mode & FMODE_EXCL) ? filp : NULL,
> -				 NULL);
> +				 filp->private_data, NULL);
>   	if (IS_ERR(bdev))
>   		return PTR_ERR(bdev);
>   
> @@ -517,8 +520,7 @@ static int blkdev_open(struct inode *inode, struct file *filp)
>   
>   static int blkdev_release(struct inode *inode, struct file *filp)
>   {
> -	blkdev_put(I_BDEV(filp->f_mapping->host),
> -		   (filp->f_mode & FMODE_EXCL) ? filp : NULL);
> +	blkdev_put(I_BDEV(filp->f_mapping->host), filp->private_data);
>   	return 0;
>   }
>   
Other than that:

Reviewed-by: Hannes Reinecke <hare at suse.de>

Cheers,

Hannes