gdisk-created Bios Boot Partition created with NO fs, reports fs TYPE=ext4. Bug/why?

gdisk-created Bios Boot Partition created with NO fs, reports fs TYPE=ext4. Bug/why?

[grantksupport]

I'm not entirely sure this is the right list for this question, but it IS ext4 'involved'.  So ...

I create a GPT Bios Boot Partition on a clean disk

	sgdisk -z /dev/sdc
	sgdisk -o /dev/sdc
	sgdisk -n 1:2048:+1M    -t 1:ef02  -c 1:"BIOS Boot"           /dev/sdc

IIUC, at this point, the partition should exist with NO filesystem.

But, if I check with blkid

	blkid /dev/sdc1
		/dev/sdc1: LABEL="RAID_BOOT" UUID="8a828baa-f315-4456-88d2-ff14849eb705" TYPE="ext4" PARTLABEL="BIOS Boot" PARTUUID="2b3b10b1-a458-481e-872c-bada7d244b13" 

Note that it IDs the filesystem type as

	TYPE="ext4"

Why?

Bios Boot Partition should have NO filesystem.

Is blkid correct?  Is there, or isn't there a fs on that partition?

if there isn't, what's causint the 'false' report?

If there IS, how do I make sure there isn't?

grant

Re: gdisk-created Bios Boot Partition created with NO fs, reports fs TYPE=ext4. Bug/why?

[Darrick J. Wong]

On Sun, Feb 15, 2015 at 10:38:56AM -0800, grantksupport@operamail.com wrote:
> I'm not entirely sure this is the right list for this question, but it IS ext4 'involved'.  So ...
> 
> I create a GPT Bios Boot Partition on a clean disk
> 
> 	sgdisk -z /dev/sdc
> 	sgdisk -o /dev/sdc
> 	sgdisk -n 1:2048:+1M    -t 1:ef02  -c 1:"BIOS Boot"           /dev/sdc
> 
> IIUC, at this point, the partition should exist with NO filesystem.
> 
> But, if I check with blkid
> 
> 	blkid /dev/sdc1
> 		/dev/sdc1: LABEL="RAID_BOOT" UUID="8a828baa-f315-4456-88d2-ff14849eb705" TYPE="ext4" PARTLABEL="BIOS Boot" PARTUUID="2b3b10b1-a458-481e-872c-bada7d244b13" 
> 
> Note that it IDs the filesystem type as
> 
> 	TYPE="ext4"
> 
> Why?

Wiping the partition table doesn't erase filesystem superblocks, so if there
previously was an sdc1 with an ext4 partition and the new sdc1 starts at the
same offset, the old fs is still accessible.

> Bios Boot Partition should have NO filesystem.
> 
> Is blkid correct?  Is there, or isn't there a fs on that partition?
> 
> if there isn't, what's causint the 'false' report?
> 
> If there IS, how do I make sure there isn't?

wipefs.

--D
> 
> grant
> 
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Re: gdisk-created Bios Boot Partition created with NO fs, reports fs TYPE=ext4. Bug/why?

[grantksupport]

On Mon, Feb 16, 2015, at 10:38 AM, Darrick J. Wong wrote:
> Wiping the partition table doesn't erase filesystem superblocks, so if there
> previously was an sdc1 with an ext4 partition and the new sdc1 starts at the
> same offset, the old fs is still accessible.
...
> wipefs.

Starting with what I had most recently ...

stopping the arrays

	mdadm --stop /dev/md0
	mdadm --stop /dev/md1

zero'ing out the superblocks

	mdadm --zero-superblock /dev/sdc3
	mdadm --zero-superblock /dev/sdd3
	mdadm --zero-superblock /dev/sdc4
	mdadm --zero-superblock /dev/sdd4

wiping the drive details

	wipefs --all --force /dev/sdc1
	wipefs --all --force /dev/sdc2
	wipefs --all --force /dev/sdc3
	wipefs --all --force /dev/sdc4
	wipefs --all --force /dev/sdc
	wipefs --all --force /dev/sdd1
	wipefs --all --force /dev/sdd2
	wipefs --all --force /dev/sdd3
	wipefs --all --force /dev/sdd4
	wipefs --all --force /dev/sdd

creating new partition info

	sgdisk -z /dev/sdc
	sgdisk -o /dev/sdc
	sgdisk -n 1:2048:+1M    -t 1:ef02  -c 1:"BIOS Boot"           /dev/sdc
	sgdisk -n 2:+0M:+300M   -t 2:ef00  -c 2:"EFI System"          /dev/sdc
	sgdisk -p /dev/sdc
		...
		Number  Start (sector)    End (sector)  Size       Code  Name
		   1            2048            4095   1024.0 KiB  EF02  BIOS Boot
		   2            4096          618495   300.0 MiB   EF00  EFI System

replicating to the other drive

	sgdisk -R=/dev/sdd /dev/sdc

& randomizing its GUID

	sgdisk -G /dev/sdd

checking now

	blkid /dev/sdc1
		/dev/sdc1: PARTLABEL="BIOS Boot" PARTUUID="c374b718-3f28-49e8-9d35-452844288233" 
	blkid /dev/sdd1
		/dev/sdd1: PARTLABEL="BIOS Boot" PARTUUID="547ad9ec-3e9c-44a4-ac05-e3f244280675" 

perfect.

thanks