Re: [PATCH v27 04/10] fs/ntfs3: Add file operations and implementation

["Pali Rohár" <pali@kernel.org>]

On Thursday 29 July 2021 16:49:37 Konstantin Komarov wrote:
> diff --git a/fs/ntfs3/file.c b/fs/ntfs3/file.c
> new file mode 100644
> index 000000000..b4369c61a
> --- /dev/null
> +++ b/fs/ntfs3/file.c
> @@ -0,0 +1,1130 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + *
> + * Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved.
> + *
> + *  regular file handling primitives for ntfs-based filesystems
> + */
> +#include <linux/backing-dev.h>
> +#include <linux/buffer_head.h>
> +#include <linux/compat.h>
> +#include <linux/falloc.h>
> +#include <linux/fiemap.h>
> +#include <linux/msdos_fs.h> /* FAT_IOCTL_XXX */
> +#include <linux/nls.h>
> +
> +#include "debug.h"
> +#include "ntfs.h"
> +#include "ntfs_fs.h"
> +
> +static int ntfs_ioctl_fitrim(struct ntfs_sb_info *sbi, unsigned long arg)
> +{
> +	struct fstrim_range __user *user_range;
> +	struct fstrim_range range;
> +	struct request_queue *q = bdev_get_queue(sbi->sb->s_bdev);
> +	int err;
> +
> +	if (!capable(CAP_SYS_ADMIN))
> +		return -EPERM;
> +
> +	if (!blk_queue_discard(q))
> +		return -EOPNOTSUPP;
> +
> +	user_range = (struct fstrim_range __user *)arg;
> +	if (copy_from_user(&range, user_range, sizeof(range)))
> +		return -EFAULT;
> +
> +	range.minlen = max_t(u32, range.minlen, q->limits.discard_granularity);
> +
> +	err = ntfs_trim_fs(sbi, &range);
> +	if (err < 0)
> +		return err;
> +
> +	if (copy_to_user(user_range, &range, sizeof(range)))
> +		return -EFAULT;
> +
> +	return 0;
> +}
> +
> +static long ntfs_ioctl(struct file *filp, u32 cmd, unsigned long arg)
> +{
> +	struct inode *inode = file_inode(filp);
> +	struct ntfs_sb_info *sbi = inode->i_sb->s_fs_info;
> +	u32 __user *user_attr = (u32 __user *)arg;
> +
> +	switch (cmd) {
> +	case FAT_IOCTL_GET_ATTRIBUTES:
> +		return put_user(le32_to_cpu(ntfs_i(inode)->std_fa), user_attr);
> +
> +	case FAT_IOCTL_GET_VOLUME_ID:
> +		return put_user(sbi->volume.ser_num, user_attr);
> +
> +	case FITRIM:
> +		return ntfs_ioctl_fitrim(sbi, arg);
> +	}
> +	return -ENOTTY; /* Inappropriate ioctl for device */
> +}

Hello! What with these two FAT_* ioctls in NTFS code? Should NTFS driver
really implements FAT ioctls? Because they looks like some legacy API
which is even not implemented by current ntfs.ko driver.

Specially, should FS driver implements ioctl for get volume id which in
this way? Because basically every fs have some kind of uuid / volume id
and they can be already retrieved by appropriate userspace tool.