Re: [Libguestfs] Wrong deficit calculation in virt-resize.

Hello guys! I tried to shrink a partition when resizing an image using virt-resize. The numbers and result are weird. ================BEFORE================ ><fs> blockdev-getsize64 /dev/sdc 4294967296 ><fs> part-list /dev/sdc [0] = { part_num: 1 part_start: 65536 part_end: 2193555455 part_size: 2193489920 } [1] = { part_num: 2 part_start: 2193555456 part_end: 4294967295 part_size: 2101411840 } ><fs> list-filesystems /dev/sdc1: ext3 /dev/sdc2: ntfs So I have two parititons up to image end, and 64k block at the start. I wanted to shrink the last partition by 1MB (for test, yeah). I shrank the filesystem by 1MB but virt-resize refused to resize to 4095MB image requesting ~2MB more (the numbers you can see in log attached). So I had to shrink the filesystem by 4MB from original: ><fs> debug sh 'ntfsresize -f --info /dev/sdc2' ... Cluster size : 4096 bytes Current volume size: 2097213952 bytes (2098 MB) Current device size: 2101411840 bytes (2102 MB) ... ===============AFTER================== Now virt-resize succeeded. But the deficit miscalculation gave its result. ><fs> blockdev-getsize64 /dev/sda 4293918720 ><fs> part-list /dev/sda [0] = { part_num: 1 part_start: 65536 part_end: 2193555455 part_size: 2193489920 } [1] = { part_num: 2 part_start: 2193555456 part_end: 4291690495 part_size: 2098135040 } So I have 2228225 bytes after last partition empty. ><fs> debug sh 'ntfsresize -f --info /dev/sda2' Current volume size: 2098131456 bytes (2099 MB) Current device size: 2098135040 bytes (2099 MB) FS is ok, it fills the partition. ======================================== I looked at resize.ml and saw complex calculations of GPT header/end, alignment overhead and so on. I wondered whether virt-resize would create GPT on new image, but it didnt. Everything remained as before except empty space at the end. So the question is: is there a bug with deficit calculation or do I miss anything?