Re: [PATCH] btrfs: add missing check for nocow and compression inode flags

Nikolay Borisov
2020-07-10T14:55:31Z

On 10.07.20 г. 16:34 ч., David Sterba wrote:
> On Fri, Jul 10, 2020 at 01:10:25PM +0300, Nikolay Borisov wrote:
>>> +static int check_fsflags(unsigned int old_flags, unsigned int flags)
>>> {
>>> if (flags & ~(FS_IMMUTABLE_FL | FS_APPEND_FL | \
>>> FS_NOATIME_FL | FS_NODUMP_FL | \
>>> @@ -174,9 +177,19 @@ static int check_fsflags(unsigned int flags)
>>> FS_NOCOW_FL))
>>> return -EOPNOTSUPP;
>>>
>>> + /* COMPR and NOCOMP on new/old are valid */
>>> if ((flags & FS_NOCOMP_FL) && (flags & FS_COMPR_FL))
>>> return -EINVAL;
>>>
>>> + if ((flags & FS_COMPR_FL) && (flags & FS_NOCOW_FL))
>>> + return -EINVAL;
>>> +
>>> + /* NOCOW and compression options are mutually exclusive */
>>> + if ((old_flags & FS_NOCOW_FL) && (flags & (FS_COMPR_FL | FS_NOCOMP_FL)))
>>
>> Why is NOCOW and setting NOCOMP (which would really be a NOOP) an
>> invalid combination?
>
> The options are not conflicting directly, like for the compression and
> nodatacow, but it still is related to compression so it does not feel
> right to allow that even if it's a noop.
>

Please put this reasoning in the changelog.