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SubjectRe: [PATCH v7 3/3] fs: fat: add ioctl method in fat filesystem driver
Date
ChenGuanqiao <chen.chenchacha@foxmail.com> writes:

> +static int fat_check_d_characters(char *label, unsigned long len)
> +{
> + int i;
> +
> + for (i = 0; i < len; ++i) {
> + switch (label[i]) {
> + case '0' ... '9':
> + case 'A' ... 'Z':
> + case '_':
> + case 0x20:
> + continue;

I didn't check though, what windows do if label = "a b c"? (I.e. invalid
name as dirent name)

> +static int fat_ioctl_get_volume_label(struct inode *inode,
> + u8 __user *vol_label)
> +{
> + int err = 0;
> + struct buffer_head *bh;
> + struct msdos_dir_entry *de;
> + struct super_block *sb = inode->i_sb;
> + char buffer[MSDOS_NAME] = {0};

Why initialize buffer?

> + inode = d_inode(sb->s_root);
> +
> + err = fat_get_volume_label_entry(inode, &bh, &de);
> + if (err)
> + goto out;

The dir traverse has to be had lock.

> + inode_lock_shared(inode);
> + memcpy(buffer, de->name, MSDOS_NAME);
> + brelse(bh);
> + inode_unlock_shared(inode);
> +
> + if (copy_to_user(vol_label, buffer, MSDOS_NAME))
> + err = -EFAULT;

No issue to copy to user memory under locking.

> +static int fat_ioctl_set_volume_label(struct file *file,
> + u8 __user *vol_label)
> +{

[...]

> + err = fat_check_d_characters(label, sizeof(label));
> + if (err)
> + goto out;
> +
> + err = mnt_want_write_file(file);
> + if (err)
> + goto out;
> +
> + down_write(&sb->s_umount);
> + inode_lock(inode);

BTW, lock order is tested with LOCKDEP?

> + /* Synchronize the data together */
> + err = sync_dirty_buffer(boot_bh);
> + if (err)
> + goto out_boot_brelse;

> + err = sync_dirty_buffer(vol_bh);
> + if (err)
> + goto out_boot_brelse;

Probably, we don't need to sync vol_bh. And in the case of adding new
entry, now already doesn't sync.
--
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

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