linux-kernel - Re: PROBLEM: BLKPG_DEL_PARTITION with GENHD_FL_NO_PART used to return ENXIO, now returns EINVAL

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Date: Tue, 16 Jan 2024 21:23:35 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: Christoph Hellwig <hch@...radead.org>,
 Allison Karlitskaya <allison.karlitskaya@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
 Jens Axboe <axboe@...nel.dk>, "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: PROBLEM: BLKPG_DEL_PARTITION with GENHD_FL_NO_PART used to return
 ENXIO, now returns EINVAL

Hi, Christoph

在 2024/01/16 18:47, Christoph Hellwig 写道:
> Hi Allison,
> 
> please try this minimal fix.  I need to double check if we historically
> returned ENXIO or EINVAL for adding / resizing partitions, which would
> make things more complicated.  Or maybe you already have data for that
> at hand?
> 
> diff --git a/block/ioctl.c b/block/ioctl.c
> index 9c73a763ef8838..f2028e39767821 100644
> --- a/block/ioctl.c
> +++ b/block/ioctl.c
> @@ -21,7 +21,7 @@ static int blkpg_do_ioctl(struct block_device *bdev,
>   	sector_t start, length;
>   
>   	if (disk->flags & GENHD_FL_NO_PART)
> -		return -EINVAL;
> +		return -ENXIO;

I think this might not be a proper fix, the reason if that before this
condition is added, -ENXIO is returned from bdev_del_partition(). And
there are also some other error number like -EACCES,-EFAULT following,
so this change will still make changes for user in other cases.

How about following patch?

diff --git a/block/ioctl.c b/block/ioctl.c
index 4160f4e6bd5b..ec012cf910dc 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -20,8 +20,6 @@ static int blkpg_do_ioctl(struct block_device *bdev,
         struct blkpg_partition p;
         long long start, length;

-       if (disk->flags & GENHD_FL_NO_PART)
-               return -EINVAL;
         if (!capable(CAP_SYS_ADMIN))
                 return -EACCES;
         if (copy_from_user(&p, upart, sizeof(struct blkpg_partition)))
@@ -38,6 +36,9 @@ static int blkpg_do_ioctl(struct block_device *bdev,
         start = p.start >> SECTOR_SHIFT;
         length = p.length >> SECTOR_SHIFT;

+       if (disk->flags & GENHD_FL_NO_PART)
+               return -EINVAL;
+
         switch (op) {
         case BLKPG_ADD_PARTITION:
                 /* check if partition is aligned to blocksize */

Thanks,
Kuai


>   	if (!capable(CAP_SYS_ADMIN))
>   		return -EACCES;
>   	if (copy_from_user(&p, upart, sizeof(struct blkpg_partition)))
> 
> .
>