Re: [f2fs-dev] [PATCH v2] libf2fs: don't allow mkfs / fsck on non power-of-2 zoned devices

[Pankaj Raghav <p.raghav@samsung.com>]

Hi Jaegeuk,

On 2022-04-13 19:03, Jaegeuk Kim wrote
>> @@ -882,6 +882,11 @@ static int open_check_fs(char *path, int flag)
>>  	return open(path, O_RDONLY | flag);
>>  }
>>  
>> +static int is_power_of_2(unsigned long n)
> 
> So, this needs to check 2MB alignment only?
> 
As I explained in the v1 thread, zoned support for f2fs assumes po2 zone
sizes. For e.g.,
static int __f2fs_issue_discard_zone(struct f2fs_sb_info *sbi,
		struct block_device *bdev, block_t blkstart, block_t blklen)
{
	sector_t sector, nr_sects;
	block_t lblkstart = blkstart;
	int devi = 0;
...
...
		// Assumes zone sectors to be po2
		if (sector & (bdev_zone_sectors(bdev) - 1) ||
				nr_sects != bdev_zone_sectors(bdev)) {
			f2fs_err(sbi, "(%d) %s: Unaligned zone reset attempted (block %x + %x)",
				 devi, sbi->s_ndevs ? FDEV(devi).path : "",
				 blkstart, blklen);
			return -EIO;
		}

...
}

So until non power of 2 zoned devices are supported in block layer and
f2fs, it is safer to reject non power of 2 devices during mkfs time. I
hope it clarifies.


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