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Add clearing of ZFS labels 

ZFS labels were not cleared by GParted when clearing old file system
signatures.

    # wget https://git.kernel.org/cgit/utils/util-linux/util-linux.git/plain/tests/ts/blkid/images-fs/zfs.img.bz2
    # bzip2 -dc zfs.img.bz2 > /dev/sdb1
    [In GParted format to cleared /dev/sdb1]
    # blkid /dev/sdb1
    /dev/sdb1: LABEL="tank" UUID="1782036546311300980" UUID_SUB="13179280127379850514" TYPE="zfs_member"

Update to also zero all 4 ZFS labels.

NOTE:
GParted now writes a little over 1 MiB when clearing old file system
signatures.  As this is performed in the main thread the UI is not able
to respond during this action.  Testing this on a range of USB flash
keys and hard drives found the slowest normal time to write this was
0.25 seconds, with an occasional outlier up to 2.8 seconds from a USB
flash key.  This is considered acceptable.
This commit is contained in:
Mike Fleetwood 2015-10-31 12:55:07 +00:00 committed by Curtis Gedak
parent eec78cd2b2
commit 32b5106aa1
1 changed files with 34 additions and 12 deletions
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46
src/GParted_Core.cc
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@ -3623,14 +3623,24 @@ bool GParted_Core::erase_filesystem_signatures( const Partition & partition, Ope
// don't try to surgically overwrite just the few bytes of each signature as this
// code overwrites whole sectors and it embeds more knowledge that is necessary.
//
// First byte range from offset 0 of length 68 KiB covers the primary super block
// of all currently supported file systems and is also likely to include future
// file system super blocks too. Only a few file systems have super blocks and
// signatures located elsewhere.
// First byte range from offset 0 of length 512 KiB covers the primary super
// block of all currently supported file systems and is also likely to include
// future file system super blocks too. Only a few file systems have super
// blocks and signatures located elsewhere.
//
// Btrfs super blocks are located at: 64 KiB, 64 MiB, 256 GiB and 1 PiB.
// (The super block at 64 KiB will be erased by the zeroing from offset 0. Other
// super block mirror copies need to be explicitly cleared).
// https://btrfs.wiki.kernel.org/index.php/On-disk_Format#Superblock
//
// ZFS labels are 256 KiB in size and 4 copies are stored on every member device,
// 2 at the beginning and 2 at the end of the device, aligned to 256 KiB. (The
// front two labels, L0 and L1, will be erased by the zeroing from offset 0. The
// back two labels, L2 and L3, need to be explicitly cleared).
// Reference:
// ZFS On-Disk Specification
// http://maczfs.googlecode.com/files/ZFSOnDiskFormat.pdf
//
// Linux Software RAID metadata 0.90 stores it's super block at 64 KiB before the
// end of the device, aligned to 64 KiB boundary. Length 4 KiB.
// Ref: mdadm/super0.c load_super0()
@ -3646,19 +3656,31 @@ bool GParted_Core::erase_filesystem_signatures( const Partition & partition, Ope
// Nilfs2 secondary super block is located at the last whole 4 KiB block.
// Ref: nilfs-utils-2.1.4/include/nilfs2_fs.h
// #define NILFS_SB2_OFFSET_BYTES(devsize) ((((devsize) >> 12) - 1) << 12)
//
// NOTE:
// Most of the time partitions are aligned to whole MiBs so the writing of zeros
// at offsets -64 KiB and -8 KiB will be overwriting zeros already just written
// at offset -512 KiB, length 512 KiB. This will double write 12 KiB of zeros.
// However partitions don't have to be MiB aligned and real disk drives generally
// aren't an exact multiple of 1024^2 bytes in size either. So zeroing at offsets
// -64 KiB and -8 KiB with their smaller rounding / alignment requirements will
// write outside the -512 KiB zeroed region and needs to be kept. Because of the
// small amount of double writing it is not worth the effort to suppress it when
// not needed.
struct {
Byte_Value offset; //Negative offsets work backwards from the end of the partition
Byte_Value rounding; //Minimum desired rounding for offset
Byte_Value length;
} ranges[] = {
//offset , rounding , length
{ 0LL , 1LL , 68LL * KIBIBYTE }, // All primary super blocks
{ 64LL * MEBIBYTE, 1LL , 4LL * KIBIBYTE }, // Btrfs super block mirror copy
{ 256LL * GIBIBYTE, 1LL , 4LL * KIBIBYTE }, // Btrfs super block mirror copy
{ 1LL * PEBIBYTE, 1LL , 4LL * KIBIBYTE }, // Btrfs super block mirror copy
{ -64LL * KIBIBYTE, 64LL * KIBIBYTE, 4LL * KIBIBYTE }, // SWRaid metadata 0.90 super block
{ -8LL * KIBIBYTE, 4LL * KIBIBYTE, 8LL * KIBIBYTE } // @-8K SWRaid metadata 1.0 super block
// and @-4K Nilfs2 secondary super block
//offset , rounding , length
{ 0LL , 1LL , 512LL * KIBIBYTE }, // All primary super blocks
{ 64LL * MEBIBYTE, 1LL , 4LL * KIBIBYTE }, // Btrfs super block mirror copy
{ 256LL * GIBIBYTE, 1LL , 4LL * KIBIBYTE }, // Btrfs super block mirror copy
{ 1LL * PEBIBYTE, 1LL , 4LL * KIBIBYTE }, // Btrfs super block mirror copy
{ -512LL * KIBIBYTE, 256LL * KIBIBYTE, 512LL * KIBIBYTE }, // ZFS labels L2 and L3
{ -64LL * KIBIBYTE, 64LL * KIBIBYTE, 4LL * KIBIBYTE }, // SWRaid metadata 0.90 super block
{ -8LL * KIBIBYTE, 4LL * KIBIBYTE, 8LL * KIBIBYTE } // @-8K SWRaid metadata 1.0 super block
// and @-4K Nilfs2 secondary super block
} ;
for ( unsigned int i = 0 ; overall_success && i < sizeof( ranges ) / sizeof( ranges[0] ) ; i ++ )
{