linux-kernel - Re: [PATCH] block: fix ioctl return error with GENHD_FL_NO

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Date:   Tue, 17 Oct 2023 17:26:32 +0800
From:   "Wang, Li" <li.wang@...driver.com>
To:     Li Lingfeng <lilingfeng3@...wei.com>, axboe@...nel.dk,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] block: fix ioctl return error with GENHD_FL_NO_PART

refer to previous codes without GENHD_FL_NO_PART, bdev_del_partition() 
return -ENXIO:

Thanks.

vim block/ioctl.c +35

static int blkpg_do_ioctl(struct block_device *bdev,
                           struct blkpg_partition __user *upart, int op)
{
...
         if (disk->flags & GENHD_FL_NO_PART)
                 return -EINVAL;
...
         if (op == BLKPG_DEL_PARTITION)
                 return bdev_del_partition(disk, p.pno);

block/partitions/core.c:479

int bdev_del_partition(struct gendisk *disk, int partno)
{
         struct block_device *part = NULL;
         int ret = -ENXIO;

         mutex_lock(&disk->open_mutex);
         part = xa_load(&disk->part_tbl, partno);
         if (!part)
                 goto out_unlock;

         ret = -EBUSY;
         if (part->bd_openers)
                 goto out_unlock;

         delete_partition(part);
         ret = 0;
out_unlock:
         mutex_unlock(&disk->open_mutex);
         return ret;
}

On 10/17/2023 16:58, Li Lingfeng wrote:
> I don't think so.
>
> GENHD_FL_NO_PART means "partition support is disabled". If users try 
> to add or resize partition on the disk with this flag, kernel should 
> remind them that the parameter of device is wrong.
> So I think it's appropriate to return -EINVAL.
>
> Thanks.
>
> 在 2023/10/17 16:09, Li Wang 写道:
>> GENHD_FL_NO_PART means no device(-ENXIO), not parameter error(-EINVAL).
>>
>> test case with parted command:
>> @dd if=/dev/zero of=./blk-file bs=1M count=200
>> @losetup /dev/loop0 ./blk-file
>> @parted -s /dev/loop0 mklabel MSDOS
>> Error: Partition(s) 1, ..., 64 on /dev/loop0 have been written,
>> but we have been unable to inform the kernel of the change,
>> probably because it/they are in use. As a result,
>> the old partition(s) will remain in use. You should reboot now
>> before making further changes.
>> @echo $?
>> 1
>>
>> Fixes: 1a721de8489f ("block: don't add or resize partition on the 
>> disk with GENHD_FL_NO_PART")
>> Signed-off-by: Li Wang <li.wang@...driver.com>
>> ---
>>   block/ioctl.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/block/ioctl.c b/block/ioctl.c
>> index d5f5cd61efd7..701c64cd67e8 100644
>> --- a/block/ioctl.c
>> +++ b/block/ioctl.c
>> @@ -21,7 +21,7 @@ static int blkpg_do_ioctl(struct block_device *bdev,
>>       long long start, length;
>>         if (disk->flags & GENHD_FL_NO_PART)
>> -        return -EINVAL;
>> +        return -ENXIO;
>>       if (!capable(CAP_SYS_ADMIN))
>>           return -EACCES;
>>       if (copy_from_user(&p, upart, sizeof(struct blkpg_partition)))