I have a Sony Xperia Z5 Compact, and I was finding strange that the storage manager showed that the system was filling 20GB of the 32GB internal storage, so I went to dig a little further into this.
I found that the data partition is p42 in the internal rom using TWRP's fdisk, which correctly reports it as having 23GB (I haven't found how to get the TWRP terminal output here, though). However, using fdisk with the device fully booted up, via ADB shell, I get this:
suzuran:/ # fdisk -l /dev/block/mmcblk0 Disk /dev/block/mmcblk0: 31.2 GB, 31272730624 bytes 255 heads, 63 sectors/track, 3802 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/block/mmcblk0p1 1 3803 30539775+ ee EFI GPT
not showing the full partition table...
However, when I try to read the partition, it gives no errors:
suzuran:/ # dd if=/dev/block/mmcblk0p42 of=/dev/null 48365568+0 records in 48365568+0 records out 24763170816 bytes transferred in 246.927 secs (100285391 bytes/sec)
Reading the entire storage also gives no errors:
suzuran:/ # dd if=/dev/block/mmcblk0 of=/dev/null 61079552+0 records in 61079552+0 records out 31272730624 bytes transferred in 365.211 secs (85629213 bytes/sec)
But when mounted, either booted or inside TWRP (I also mounted it manually) it shows only a 8GB size:
suzuran:/ # df Filesystem 1K-blocks Used Available Use% Mounted on [ other skipped mounts ] /dev/block/mmcblk0p43 5215496 1188900 4026596 23% /system /dev/block/mmcblk0p42 8641912 6071544 2570368 71% /data /dev/block/mmcblk0p41 197472 188 197284 1% /cache /dev/block/mmcblk0p3 81872 57808 24064 71% /firmware /dev/block/mmcblk0p31 28144 164 27980 1% /persist /dev/block/mmcblk0p39 14327 160 14167 2% /idd /dev/block/loop0 92656 980 91676 2% /su
I'm using LineageOS, but in the stock Sony rom I had the same issue, only didn't have the tools to check this further.
Anyone had this issue before or can help me with this?
Edit: I just found about 'blockdev' command:
suzuran:/ # blockdev --getsize64 /dev/block/bootdevice/by-name/userdata 24763170816
which gives the correct size of the partition. What's happening with the 'mount' command? Could this be kernel related? If so, why does it happen in TWRP too?