[Q] Understanding partitions' layout topic

I have some difficulties understanding partitions' layout of my phone. (Huawei G6-U10 ***NOT*** rooted yet)
As spec:

4 GB Internal Memory
|__ 2 GB reserved

|__ 2 GB Internal Storage

|__ Memory android option menu shows ~2 GB total (1,91 GB) but only ~1 GB (1,03 GB) available.

If I connect my phone through MTP it shows as internal memory just a partition of ~ 1 GB (994 MB)

32 GB external SD

Code:

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major minor #blocks name

7    1    9387 loop1
7    2    16664 loop2
7    3    10427 loop3
7    4    15624 loop4
253    0    196608 zram0
179    0 3866624 mmcblk0
179    1    512 mmcblk0p1
179    2        32 mmcblk0p2
179    3        32 mmcblk0p3
179    4    500 mmcblk0p4
179    5    500 mmcblk0p5
179    6    5592 mmcblk0p6
179    7    1024 mmcblk0p7
179    8    65536 mmcblk0p8
179    9    4096 mmcblk0p9
179    10    4096 mmcblk0p10
179    11    98304 mmcblk0p11
179    12    4096 mmcblk0p12
179    13        1 mmcblk0p13
179    14        8 mmcblk0p14
179    15    32768 mmcblk0p15
179    16    65536 mmcblk0p16
179    17    8192 mmcblk0p17
179    18    12288 mmcblk0p18
179    19    16384 mmcblk0p19
179    20    262144 mmcblk0p20
179    21    196608 mmcblk0p21
179    22    4096 mmcblk0p22
179    23 1048576 mmcblk0p23
179    24 1048576 mmcblk0p24
179    25    974831 mmcblk0p25
179    32    2048 mmcblk0rpmb
179    64 30748672 mmcblk1
179    65 30744576 mmcblk1p1
254    1    9387 dm-1
254    4    15624 dm-4
254    2    16663 dm-2
254    3    10426 dm-3

---

Then I listed partition symlink by name

Code:

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ls -al /dev/block/platform/msm_sdcc.1/by-name
DDR -> /dev/block/mmcblk0p3
aboot -> /dev/block/mmcblk0p6
bkbootup -> /dev/block/mmcblk0p16
boot -> /dev/block/mmcblk0p18
cache -> /dev/block/mmcblk0p21
cust -> /dev/block/mmcblk0p20
fsc -> /dev/block/mmcblk0p13
fsg -> /dev/block/mmcblk0p12
grow -> /dev/block/mmcblk0p25
log -> /dev/block/mmcblk0p15
misc -> /dev/block/mmcblk0p22
modem -> /dev/block/mmcblk0p11
modemst1 -> /dev/block/mmcblk0p9
modemst2 -> /dev/block/mmcblk0p10
oeminfo -> /dev/block/mmcblk0p8
pad -> /dev/block/mmcblk0p7
persist -> /dev/block/mmcblk0p17
recovery -> /dev/block/mmcblk0p19
rpm -> /dev/block/mmcblk0p4
sbl1 -> /dev/block/mmcblk0p1
sdi -> /dev/block/mmcblk0p2
ssd -> /dev/block/mmcblk0p14
system -> /dev/block/mmcblk0p23
tz -> /dev/block/mmcblk0p5
userdata -> /dev/block/mmcblk0p24

---

Assuming a blocksize of 1024, I can see that sizes of mmcblk0p23 (/system) and mmcblk0p24 (/userdata) are 1 GB each.


1) The space unavailable from internal storage, is the /userdata partition?

2) Of the 2 GB Android doesn't show at all, 1 is obviously occupied by /system, but if the sum of all the other partitions on the first block device (except /userdata and /system) is equal to ~1,67 GB, how can it resides on the 1 GB remaining space?

3)What's the /grow mountpoint?