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Clear nilfs2 secondary super block (#688882) 

Wipefs only clears the nilfs2 file system signature from the primary
super block at the start of the partition.  This is enough for blkid to
no longer detect the file system.  However parted (>= 2.4 with nilfs2
support) and therefore GParted still detect the file system using the
secondary super block at the end of the partition.

    # mkfs.nilfs2 /dev/sda12
    # wipefs -a /dev/sda12
    2 bytes were erased at offset 0x00000406 (nilfs2): 34 34
    # blkid /dev/sda12
    # parted /dev/sda12 print
    Model: Unknown (unknown)
    Disk /dev/sda12: 1074MB
    Sector size (logical/physical): 512B/512B
    Partition Table: loop
    Disk Flags:

    Number  Start  End     Size    File system  Flags
     1      0.00B  1074MB  1074MB  nilfs2

Overwrite the nilfs2 secondary super block at the end of the partition
with 4K block of zeros.  Always do this just in case the partition
contains a nilfs secondary super block but is detected as a different
file system.  Such an example was documented in an earlier commit
message.

Bug #688882 - Improve clearing of file system signatures
This commit is contained in:
Mike Fleetwood 2013-02-25 23:40:50 +00:00 committed by Curtis Gedak
parent 0b164b168d
commit 38ca0db343
1 changed files with 54 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
src/GParted_Core.cc
View File

@ -3155,18 +3155,32 @@ bool GParted_Core::erase_filesystem_signatures( const Partition & partition, Ope
overall_success = wipefs_success ;
}
//Get device, disk & partition and open the device.
//Get device, disk & partition and open the device. Allocate buffer and fill with
// zeros. Buffer size is the greater of 4 KiB and the sector size.
PedDevice* lp_device = NULL ;
PedDisk* lp_disk = NULL ;
PedPartition* lp_partition = NULL ;
bool device_is_open = false ;
Byte_Value bufsize = 4LL * KIBIBYTE ;
char * buf = NULL ;
if ( open_device_and_disk( partition .device_path, lp_device, lp_disk )
&& ( lp_partition = ped_disk_get_partition_by_sector( lp_disk, partition .get_sector() ) ) )
{
if ( ped_device_open( lp_device ) )
{
device_is_open = true ;
bufsize = std::max( bufsize, lp_device ->sector_size ) ;
buf = static_cast<char *>( malloc( bufsize ) ) ;
if ( buf )
memset( buf, 0, bufsize ) ;
}
}
//Single copy of string for translation purposes
/*TO TRANSLATORS: looks like wrote 68.00 KiB of zeros at byte offset 0 */
const Glib::ustring wrote_zeros_msg = _("wrote %1 of zeros at byte offset %2") ;
if ( ! overall_success )
{
//Wipefs either doesn't exist or reported an error clearing the file
@ -3178,14 +3192,11 @@ bool GParted_Core::erase_filesystem_signatures( const Partition & partition, Ope
OperationDetail & od = operationdetail .get_last_child() ;
od .add_child( OperationDetail( _("clear primary signatures") ) ) ;
Byte_Value bufsize = std::max( 4LL * KIBIBYTE, lp_device ->sector_size ) ;
Byte_Value total_size = std::min( 64LL * KIBIBYTE + bufsize, partition .get_byte_length() ) ;
char * buf = static_cast<char *>( malloc( bufsize ) ) ;
Byte_Value written = 0LL ;
bool zero_success = false ;
if ( device_is_open && buf )
{
memset( buf, 0, bufsize ) ;
while ( written < total_size )
{
zero_success = ped_geometry_write( & lp_partition ->geom, buf,
@ -3195,13 +3206,12 @@ bool GParted_Core::erase_filesystem_signatures( const Partition & partition, Ope
break ;
written += bufsize ;
}
free( buf ) ;
}
if ( zero_success )
{
od .get_last_child() .add_child( OperationDetail(
String::ucompose( _("wrote %1 of zeros at byte offset %2"),
String::ucompose( wrote_zeros_msg,
Utils::format_size( written, 1 ),
0LL ),
STATUS_NONE, FONT_ITALIC ) ) ;
@ -3214,6 +3224,44 @@ bool GParted_Core::erase_filesystem_signatures( const Partition & partition, Ope
overall_success = zero_success ;
}
//Erase any nilfs2 secondary super block to prevent erroneous detection by
// libparted because wipefs didn't clear the signature in the secondary super
// block. Overwrite the last full 4 KiB block with zeros (or larger if the
// sector size is larger and possibly earlier depending on the sector alignment).
// Ref: nilfs-utils-2.1.4/include/nilfs2_fs.h
// #define NILFS_SB2_OFFSET_BYTES(devsize) ((((devsize) >> 12) - 1) << 12)
if ( overall_success )
{
OperationDetail & od = operationdetail .get_last_child() ;
od .add_child( OperationDetail( _("clear secondary signatures") ) ) ;
Byte_Value byte_offset = ( ( partition .get_byte_length() >> 12 ) - 1 ) << 12 ;
bool zero_success = false ;
if ( device_is_open && buf )
{
zero_success = ped_geometry_write( & lp_partition ->geom, buf,
byte_offset / lp_device ->sector_size,
bufsize / lp_device ->sector_size ) ;
}
if ( zero_success )
{
od .get_last_child() .add_child( OperationDetail(
String::ucompose( wrote_zeros_msg,
Utils::format_size( bufsize, 1 ),
byte_offset ),
STATUS_NONE, FONT_ITALIC ) ) ;
od .get_last_child() .set_status( STATUS_SUCCES ) ;
}
else
{
od .get_last_child() .set_status( STATUS_ERROR ) ;
}
overall_success &= zero_success ;
}
if ( buf )
free( buf ) ;
//Linux kernel doesn't maintain buffer cache coherency between the whole disk
// device and partition devices. So even though the file system signatures
// have been overwritten on the disk via a partition device, libparted reading