There is an unidentified condition that prevents udevd calling the BLKRRPART ioctl after a partition table is written. It looks like either the kernel or udevd drops device change events if they are too closely spaced in time. So, in the case where we expect udevd to call BLKRRPART, check /proc/partitions to make sure it has done so. Arbitrarily try 5 times, 100ms apart, before giving up and informing the kernel ourselves.
diskdrake allows the user to clear all partitions even when some of those partitions are currently mounted. partition_table::dos::need_to_tell_kernel() must return true in this case, as the automatic reread of the partition table triggered by udevd will fail.
The automatic rescan of the partition table is triggered by udevd. The udev rule that causes this is not present on the cut-down system that runs the classic installer.
To minimise the changes this close to mga6 release (and until we fix the bug in partition auto-allocation that mistakenly creates BIOS boot partitions non-GPT disks), reuse the BIOS_GRUB flag for flagging Empty partitions, as the real partition ID (0x00) is used to flag free space.
When no partitions on a DOS-partitioned disk are mounted, the kernel automatically rescans the partition table when it is written to disk. We shouldn't then try to update the kernel's view of the partition table, as the list of deltas we have recorded is relative to the previous state of the partition table, not the newly rescanned state. The behaviour for other partition table types is unchanged. v2 (tvignaud): just make base class assume the kernel doesn't reread, only mbr subclass overrides need_to_tell_kernel() in order to be smarter
When no partitions on a DOS-partitioned disk are mounted, the kernel automatically rescans the partition table when the file handle to the raw device is released. Currently the code opens and closes the raw device when writing the primary partition table and when writing each extended partition table segment. As the extended partition table segments form a linked list, this allows the kernel to get in and rescan the table when the list is not in a coherent state. This patch changes the code to open the raw device before writing the primary partition table and to close it only after writing the last extended partition table segment. The behaviour for other partition table types is unchanged. v2 (tvignaud): simplify by moving copies of noop funcs into the base class