On Fri, Jan 22, 2021 at 04:15:29PM +0100, Sascha Hauer wrote:
> This patch introduces the Q_PATH flag to the quotactl cmd argument.
> When given, the path given in the special argument to quotactl will
> be the mount path where the filesystem is mounted, instead of a path
> to the block device.
> This is necessary for filesystems which do not have a block device as
> backing store. Particularly this is done for upcoming UBIFS support.
>
> Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
I hate overloading quotactl even more. Why not add a new quotactl_path
syscall instead?
> +static struct super_block *quotactl_sb(dev_t dev, int cmd)
> {
> struct super_block *sb;
> bool excl = false, thawed = false;
>
> if (quotactl_cmd_onoff(cmd)) {
> excl = true;
> @@ -901,12 +887,50 @@ static struct super_block *quotactl_block(const char __user *special, int cmd)
> goto retry;
> }
> return sb;
> +}
> +
> +/*
> + * look up a superblock on which quota ops will be performed
> + * - use the name of a block device to find the superblock thereon
> + */
> +static struct super_block *quotactl_block(const char __user *special, int cmd)
> +{
> +#ifdef CONFIG_BLOCK
> + struct filename *tmp = getname(special);
> + int error;
> + dev_t dev;
>
> + if (IS_ERR(tmp))
> + return ERR_CAST(tmp);
> + error = lookup_bdev(tmp->name, &dev);
> + putname(tmp);
> + if (error)
> + return ERR_PTR(error);
> +
> + return quotactl_sb(dev, cmd);
> #else
> return ERR_PTR(-ENODEV);
> #endif
Normal kernel style would be to keep the ifdef entirely outside the
function.
> +static struct super_block *quotactl_path(const char __user *special, int cmd)
> +{
> + struct super_block *sb;
> + struct path path;
> + int error;
> +
> + error = user_path_at(AT_FDCWD, special, LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT,
> + &path);
This adds an overly long line.
> + if (error)
> + return ERR_PTR(error);
> +
> + sb = quotactl_sb(path.mnt->mnt_sb->s_dev, cmd);
I think quotactl_sb should take the superblock directly. This will
need a little refactoring of user_get_super, but will lead to much
better logic.
