Re: [PATCH 12/18] common: partitions: record whether disk is GPT or MBR partitioned

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

On 31.05.23 19:33, Marco Felsch wrote:
> On 23-05-31, Ahmad Fatoum wrote:
>> Currently, the only way to differentiate between a GPT disk and a MBR
>> one is to check whether the cdev's device has a guid (=> GPT) or a
>> nt_signature (=> MBR) device parameter. We already have a flag parameter
>> though, so let's record this info there for easy retrieval.
>>
>> We intentionally don't use the struct cdev::filetype member, because
>> we don't want to change behavior of file_detect_type().
>>
>> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
>> ---
>>  common/partitions/dos.c |  2 ++
>>  common/partitions/efi.c |  2 ++
>>  fs/fs.c                 |  4 ++++
>>  include/driver.h        | 20 +++++++++++++++++---
>>  4 files changed, 25 insertions(+), 3 deletions(-)
>>
>> diff --git a/common/partitions/dos.c b/common/partitions/dos.c
>> index ad60c0b27b46..7472824b00b9 100644
>> --- a/common/partitions/dos.c
>> +++ b/common/partitions/dos.c
>> @@ -185,6 +185,8 @@ static void dos_partition(void *buf, struct block_device *blk,
>>  	if (signature)
>>  		sprintf(blk->cdev.diskuuid, "%08x", signature);
>>  
>> +	blk->cdev.flags |= DEVFS_IS_MBR_PARTITIONED;
>> +
>>  	table = (struct partition_entry *)&buffer[446];
>>  
>>  	for (i = 0; i < 4; i++) {
>> diff --git a/common/partitions/efi.c b/common/partitions/efi.c
>> index 780a8695e8a8..df63b82afe24 100644
>> --- a/common/partitions/efi.c
>> +++ b/common/partitions/efi.c
>> @@ -449,6 +449,8 @@ static void efi_partition(void *buf, struct block_device *blk,
>>  	snprintf(blk->cdev.diskuuid, sizeof(blk->cdev.diskuuid), "%pUl", &gpt->disk_guid);
>>  	dev_add_param_string_fixed(blk->dev, "guid", blk->cdev.diskuuid);
>>  
>> +	blk->cdev.flags |= DEVFS_IS_GPT_PARTITIONED;
>> +
>>  	nb_part = le32_to_cpu(gpt->num_partition_entries);
>>  
>>  	if (nb_part > MAX_PARTITION) {
>> diff --git a/fs/fs.c b/fs/fs.c
>> index 9d8aab268ca4..2d2d327c5fbc 100644
>> --- a/fs/fs.c
>> +++ b/fs/fs.c
>> @@ -94,6 +94,10 @@ void cdev_print(const struct cdev *cdev)
>>  			printf(" table-partition");
>>  		if (cdev->flags & DEVFS_IS_MCI_MAIN_PART_DEV)
>>  			printf(" mci-main-partition");
>> +		if (cdev->flags & DEVFS_IS_GPT_PARTITIONED)
>> +			printf(" gpt-partitioned");
>> +		if (cdev->flags & DEVFS_IS_MBR_PARTITIONED)
>> +			printf(" mbr-partitioned");
>>  		if (cdev->mtd)
>>  			printf(" mtd");
>>  		printf(" )");
>> diff --git a/include/driver.h b/include/driver.h
>> index 118d2adb6750..5f2eae65466f 100644
>> --- a/include/driver.h
>> +++ b/include/driver.h
>> @@ -584,9 +584,23 @@ extern struct list_head cdev_list;
>>  #define DEVFS_PARTITION_FIXED		(1U << 0)
>>  #define DEVFS_PARTITION_READONLY	(1U << 1)
>>  #define DEVFS_IS_CHARACTER_DEV		(1U << 3)
>> -#define DEVFS_IS_MCI_MAIN_PART_DEV	(1U << 4)
>> -#define DEVFS_PARTITION_FROM_OF		(1U << 5)
>> -#define DEVFS_PARTITION_FROM_TABLE	(1U << 6)
>> +#define DEVFS_PARTITION_FROM_OF		(1U << 4)
>> +#define DEVFS_PARTITION_FROM_TABLE	(1U << 5)
>> +#define DEVFS_IS_GPT_PARTITIONED	(1U << 6)
>> +#define DEVFS_IS_MBR_PARTITIONED	(1U << 7)
>> +#define DEVFS_IS_MCI_MAIN_PART_DEV	(1U << 8)
> 
> Why do you reorder the bits here again?

I wanted the partition bits to be together.

>> +
>> +static inline bool cdev_is_gpt_partitioned(const struct cdev *master)
>> +{
>> +	return master && (master->flags & DEVFS_IS_GPT_PARTITIONED)
>> +		== DEVFS_IS_GPT_PARTITIONED;
> 
> Why not just: 'return !!(master->flags & DEVFS_IS_GPT_PARTITIONED)' ?

Left over from when this was more than one bit. I will change to:

  return master && (master->flags & DEVFS_IS_GPT_PARTITIONED)

I want to keep the NULL check, as we only set this for the master device.

Cheers,
Ahmad


> 
> Regards,
>   Marco
> 
>> +}
>> +
>> +static inline bool cdev_is_mbr_partitioned(const struct cdev *master)
>> +{
>> +	return master && (master->flags & DEVFS_IS_MBR_PARTITIONED)
>> +		== DEVFS_IS_MBR_PARTITIONED;
>> +}
>>  
>>  struct cdev *devfs_add_partition(const char *devname, loff_t offset,
>>  		loff_t size, unsigned int flags, const char *name);
>> -- 
>> 2.39.2
>>
>>
>>
> 

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