Hi, I happened to look at this commit in parted: libparted: don't trash filesystem when writing loop label http://git.savannah.gnu.org/cgit/parted.git/commit/?id=1be70093eb937f34388e06ce3731e5f56f217950
It tries to avoid stomping on the super block of whole disk file systems when the virtual partition covering the whole disk is deleted. It writes just the loop signature "GNU Parted Loopback 0" at byte offset 0 on the disk. However the XFS super block and it's signature start at byte offset 0 too, so this renders the XFS file system undetectable, effectively deleting it. With a whole disk ext4 file system, deleting the virtual partition is effectively a no-operation as the ext4 file system remains intact and is still detected on the whole disk device. It appears that deletion of the virtual loop partition is trying to be as close as possible a no-operation, yet still leave the device detected with a loop partition table. So either: 1) the device contains the loop signature or 2) contains a libparted recognised file system signature. In both cases it will still be recognised as containing a loop partition table when re-read. If something else erases the signature in the mean time then that is something else's responsibility and a new loop partition table can be re-created. Therefore I think deletion of the virtual loop partition table should truly be a no-operation. Thanks, Mike # mkfs.xfs -f /dev/sdc # dd if=/dev/sdc bs=64 count=1 2> /dev/null | hexdump -C 00000000 58 46 53 42 00 00 10 00 00 00 00 00 00 20 00 00 |XFSB......... ..| 00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 00000020 ee 09 f3 0b 4a 92 43 7f b0 1b 2f 56 bf a8 53 fc |....J.C.../V..S.| 00000030 00 00 00 00 00 10 00 04 00 00 00 00 00 00 00 80 |................| 00000040 # parted /dev/sdc GNU Parted 3.2 Using /dev/sdc Welcome to GNU Parted! Type 'help' to view a list of commands. (parted) print Model: ATA VBOX HARDDISK (scsi) Disk /dev/sdc: 8590MB Sector size (logical/physical): 512B/512B Partition Table: loop Disk Flags: Number Start End Size File system Flags 1 0.00B 8590MB 8590MB xfs (parted) rm 1 (parted) print Model: ATA VBOX HARDDISK (scsi) Disk /dev/sdc: 8590MB Sector size (logical/physical): 512B/512B Partition Table: loop Disk Flags: Number Start End Size File system Flags (parted) quit Information: You may need to update /etc/fstab. # dd if=/dev/sdc bs=64 count=1 2> /dev/null | hexdump -C 00000000 47 4e 55 20 50 61 72 74 65 64 20 4c 6f 6f 70 62 |GNU Parted Loopb| 00000010 61 63 6b 20 30 00 00 00 00 00 00 00 00 00 00 00 |ack 0...........| 00000020 ee 09 f3 0b 4a 92 43 7f b0 1b 2f 56 bf a8 53 fc |....J.C.../V..S.| 00000030 00 00 00 00 00 10 00 04 00 00 00 00 00 00 00 80 |................| 00000040
