Re: [PATCH v5 3/5] fs: split off do_getxattr from getxattr

[Stefan Roesch <shr@fb.com>]

On 12/21/21 11:18 AM, Linus Torvalds wrote:
> On Tue, Dec 21, 2021 at 11:15 AM Stefan Roesch <shr@fb.com> wrote:
>>
>> Linus, if we remove the constness, then we either need to cast away the constness (the system call
>> is defined as const) or change the definition of the system call.
> 
> You could also do it as
> 
>         union {
>                 const void __user *setxattr_value;
>                 void __user *getxattr_value;
>         };
>

Pavel brought up a very good point. By adding the kname array into the 
xarray_ctx we increase the size of io_xattr structure too much. In addition
this will also increase the size of the io_kiocb structure. The original
solution did not increase the size.

Per opcode we limit the storage space to 64 bytes. However the array itself
requires 256 bytes.
 
> if you wanted to..
> 
>                  Linus
>