Relocate GPT headers for expanded disks #158
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I am not happy of having to use Just validated that the patch is not included in TW and Ubuntu, only Fedora includes a patched parted including this change. So, hopefully, this is something we can revisit at some point in the future. |
This commit ensure the partitioner module run 'sgdisk -e /dev/disk' to fix GPT headers in case the disk was expanded or some smaller image was dumped into the disk. Fixes rancher/elemental-toolkit#1201 Signed-off-by: David Cassany <dcassany@suse.com>
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pkg/partitioner/parted.go
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| // the disk, hence it needs to be adapted to get valid sizes from parted | ||
| // print. Parted has no proper command to verify GPT headers neither a | ||
| // proper command to fix them whenever is possible in a non interactive mode. | ||
| func (pc PartedCall) HasUnallocatedSpace(printOut string) bool { |
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small nit here, better keep this private. It is parsing a string for a known pattern so also the regexp could be compiled instead of being a func wrapper
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besides, it is safe to assume that we want to always call sgdisk here in any case this pattern matches?
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besides, it is safe to assume that we want to always call sgdisk here in any case this pattern matches?
I think so and it is aligned with the --fix flag that parted should include within the next release (I am not sure which is the criteria to cut releases, since it is more than a year already since last one). So if we'd use parted from master upstream we would not need this check at all and we would simply call parted print command with --fix flag, which essentially fixes gpt headers if there is some inconsistency. So the Disk.Reload method would essentially run parted -s --fix -m <device> unit s print and it would load the disk partition table at the time it fixes GTP header inconsistencies, so the values of the disk size print outputs matches the actual disk geometry.
In parted there is no such command to actually fix headers, it can only do it on the fly in interactive mode or fully automated with the --fix flag in non interactive mode (up coming releases). sgdisk has verify and expand commands, so you have the tools to add logic to handle this situation in different scenarios if you want.
sgdisk is a well designed tool to script on top of it, parted is not that good in that regard, scripted commands are convoluted (probably to match GPT and MSDOS support in a single UI) and not as powerfull as in interactive mode. The only reason to use parted is that is supports MSDOS partition tables and it allows us to support GPT and MSDOS with a single logic or wrapper.
Signed-off-by: David Cassany <dcassany@suse.com>
This commit ensure the partitioner module run 'sgdisk -e /dev/disk' to
fix GPT headers in case the disk was expanded or some smaller image was
dumped into the disk.
Fixes rancher/elemental-toolkit#1201
Signed-off-by: David Cassany dcassany@suse.com