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

Hannes Reinecke
2023-06-07T13:14:41Z

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@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@suse.de>

Cheers,

Hannes