Re: [PATCH 1/5] btrfs: add flags to give an hint to the chunk allocator

[Goffredo Baroncelli <kreijack@libero.it>]

On 22/03/2022 20.52, Josef Bacik wrote:
> On Sun, Mar 06, 2022 at 07:14:39PM +0100, Goffredo Baroncelli wrote:
>> From: Goffredo Baroncelli <kreijack@inwind.it>
>>
>> Add the following flags to give an hint about which chunk should be
>> allocated in which disk:
>>
>> - BTRFS_DEV_ALLOCATION_HINT_DATA_PREFERRED
>>    preferred for data chunk, but metadata chunk allowed
>> - BTRFS_DEV_ALLOCATION_HINT_METADATA_PREFERRED
>>    preferred for metadata chunk, but data chunk allowed
>> - BTRFS_DEV_ALLOCATION_HINT_METADATA_ONLY
>>    only metadata chunk allowed
>> - BTRFS_DEV_ALLOCATION_HINT_DATA_ONLY
>>    only data chunk allowed
>>
>> Signed-off-by: Goffredo Baroncelli <kreijack@inwind.it>
>> ---
>>   include/uapi/linux/btrfs_tree.h | 16 ++++++++++++++++
>>   1 file changed, 16 insertions(+)
>>
>> diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
>> index b069752a8ecf..e0d842c2e616 100644
>> --- a/include/uapi/linux/btrfs_tree.h
>> +++ b/include/uapi/linux/btrfs_tree.h
>> @@ -389,6 +389,22 @@ struct btrfs_key {
>>   	__u64 offset;
>>   } __attribute__ ((__packed__));
>>   
>> +/* dev_item.type */
>> +
>> +/* btrfs chunk allocation hint */
>> +#define BTRFS_DEV_ALLOCATION_HINT_BIT_COUNT	2
>> +/* btrfs chunk allocation hint mask */
>> +#define BTRFS_DEV_ALLOCATION_HINT_MASK	\
>> +	((1 << BTRFS_DEV_ALLOCATION_HINT_BIT_COUNT) - 1)
>> +/* preferred data chunk, but metadata chunk allowed */
>> +#define BTRFS_DEV_ALLOCATION_HINT_DATA_PREFERRED	(0ULL)
>> +/* preferred metadata chunk, but data chunk allowed */
>> +#define BTRFS_DEV_ALLOCATION_HINT_METADATA_PREFERRED	(1ULL)
>> +/* only metadata chunk are allowed */
>> +#define BTRFS_DEV_ALLOCATION_HINT_METADATA_ONLY		(2ULL)
>> +/* only data chunk allowed */
>> +#define BTRFS_DEV_ALLOCATION_HINT_DATA_ONLY		(3ULL)
>> +
> 
> I also just realized you're using these as flags, so they need to be
> 
> (1ULL << 0)
> (1ULL << 1)
> (1ULL << 2)
> (1ULL << 3)
> 

Could you elaborate a bit ? These are mutual exclusive values...

> Thanks,
> 
> Josef


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