OpenWRT（x86_64）中squashfs固件磁盘空间扩容方法：Overlay扩容，带有efi的和不带efi的
在OpenWrt中，最困难，也最痛苦的就是给squashfs固件磁盘扩容了！
我是研究大神的视频后学习到的，在此自己整理的笔记，大家一起学习吧！
OpenWrt空间扩容：这波补充超有料！韩风Talk
OpenWrt的空间扩容问题，可以这么直接解决！（非f2fs文件系统的）
重要提示：在新版本OpenWrt中，如果你的磁盘是M.2口的SSD，那么你在X86设备上硬盘刷写固件时，很大概率文件系统会被写成f2fs文件系统（不是常规的ext4文件系统），并且无法在线挂载扩容，因此“很多人（M.2固态刷了squashfs固件的玩家）无法实现硬盘扩容”
PS：经过初步验证，是f2fs文件系统，还是ext4文件系统这取决于你刷机时候，PE启动的引导方式（BIOS或UEFI）！如果你是传统BIOS方式启动的系统(有的叫Legacy)，并且格式化硬盘的时候，保存为磁盘格式导致的，分区表类型为MBR格式的分区，写入固件后就是ext4文件系统；如果你是新型UEFI方式启动的系统，格式化硬盘后，分区表类型为GPT格式的分区，写入固件后就是f2fs文件系统！
但是你别担心，他们是可以相互转化的。因此，你需要注意的是：如果你是UEFI格式引导启动的PE，在格式化硬盘后别退出，再做一步“转换分区表类型为MBR格式”就可以规避f2fs文件系统的问题了！
这是分区表类型为MBR格式的分区
这是分区表类型为GPT格式的分区
识别文件系统的方法很简单：
df -Th或者lsblk -f查看即可辨别
1.安装需要的软件：
opkg update
opkg install lsblk fdisk resize2fs losetup blkid f2fs-tools tree
root@ImmortalWrt:~# opkg install lsblk fdisk resize2fs losetup blkid f2fs-tools tree
Installing lsblk (2.39-2) to root...
Downloading https://mirrors.vsean.net/openwrt/releases/23.05.3/packages/x86_64/base/lsblk_2.39-2_x86_64.ipk
Installing libmount1 (2.39-2) to root...
Downloading https://mirrors.vsean.net/openwrt/releases/23.05.3/packages/x86_64/base/libmount1_2.39-2_x86_64.ipk
Package fdisk (2.39-2) installed in root is up to date.
Installing resize2fs (1.47.0-2) to root...
Downloading https://mirrors.vsean.net/openwrt/releases/23.05.3/packages/x86_64/base/resize2fs_1.47.0-2_x86_64.ipk
Installing losetup (2.39-2) to root...
Downloading https://mirrors.vsean.net/openwrt/releases/23.05.3/packages/x86_64/base/losetup_2.39-2_x86_64.ipk
Installing blkid (2.39-2) to root...
Downloading https://mirrors.vsean.net/openwrt/releases/23.05.3/packages/x86_64/base/blkid_2.39-2_x86_64.ipk
Installing f2fs-tools (1.16.0-1) to root...
Downloading https://mirrors.vsean.net/openwrt/releases/23.05.3/packages/x86_64/base/f2fs-tools_1.16.0-1_x86_64.ipk
Installing f2fsck (1.16.0-1) to root...
Downloading https://mirrors.vsean.net/openwrt/releases/23.05.3/packages/x86_64/base/f2fsck_1.16.0-1_x86_64.ipk
Configuring f2fsck.
Configuring f2fs-tools.
Configuring resize2fs.
Configuring libmount1.
Configuring lsblk.
Configuring losetup.
Configuring blkid.
Configuring tree.可选装的软件（openwrt官方源不提供diskman）
diskman2.查看磁盘分区情况
root@ImmortalWrt:~# fdisk -l
Disk /dev/loop0: 291.06 MiB, 305201152 bytes, 596096 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
GPT PMBR size mismatch (680479 != 123091919) will be corrected by write.
The backup GPT table is corrupt, but the primary appears OK, so that will be used.
The backup GPT table is not on the end of the device.
Disk /dev/sda: 58.69 GiB, 63023063040 bytes, 123091920 sectors
Disk model: SanDisk SSD i110
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 20C60F33-AFC6-96E2-AE0B-E001AE609500
Device Start End Sectors Size Type
/dev/sda1 512 66047 65536 32M Linux filesystem
/dev/sda2 66048 680447 614400 300M Linux filesystem
/dev/sda128 34 511 478 239K BIOS boot
Partition table entries are not in disk order.我们明确了几个点：
1、我们需要操作的整个磁盘叫 /dev/sda ，总容量58.69G（Disk /dev/sda: 58.69 GiB）
2、我们需要扩容的分区是/dev/sda2 ，这里的Start是66048，原始空间300M（/dev/sda2 66048 680447 614400 300M Linux filesystem）
3.使用fdisk命令对磁盘从新分区（扩容）
1、fdisk /dev/sda扩容磁盘
2、输入p回车（打印磁盘信息），观察后确人：将来要删除的是第二个盘 /dev/sda2（以p打印的顺序为准）
root@ImmortalWrt:~# fdisk /dev/sda
Welcome to fdisk (util-linux 2.39).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
GPT PMBR size mismatch (680479 != 123091919) will be corrected by write.
The backup GPT table is corrupt, but the primary appears OK, so that will be used.
The backup GPT table is not on the end of the device. This problem will be corrected by write.
This disk is currently in use - repartitioning is probably a bad idea.
It's recommended to umount all file systems, and swapoff all swap
partitions on this disk.
Command (m for help): p
Disk /dev/sda: 58.69 GiB, 63023063040 bytes, 123091920 sectors
Disk model: SanDisk SSD i110
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 20C60F33-AFC6-96E2-AE0B-E001AE609500
Device Start End Sectors Size Type
/dev/sda1 512 66047 65536 32M Linux filesystem
/dev/sda2 66048 680447 614400 300M Linux filesystem
/dev/sda128 34 511 478 239K BIOS boot
Partition table entries are not in disk order.
Command (m for help): 3、输入d回车（删除分区命令），选择2回车（选择删除第二个分区）
Device Start End Sectors Size Type
/dev/sda1 512 66047 65536 32M Linux filesystem
/dev/sda2 66048 680447 614400 300M Linux filesystem
/dev/sda128 34 511 478 239K BIOS boot
Partition table entries are not in disk order.
Command (m for help): d
Partition number (1,2,128, default 128): 2
Partition 2 has been deleted.
Command (m for help): 4、输入n回车（创建一个新分区），输入2回车（设置盘序号还是刚刚的2号盘），然后必须要注意，之前2号盘的Start是66048，所以新创建的盘的Start也必须是66048，然后回车。
输入+5g，代表直接新建分区为5GB（这样写方便，不用计算）
Do you want to remove the signature? [Y]es/[N]o: n（移除之前的标识符这里一定要选n）
打印分区表，确认无误后，输入w（保存，正式写入，并同步分区表）
Command (m for help): n
Partition number (2-127, default 2): 2
First sector (66048-123091886, default 67584): 66048
Last sector, +/-sectors or +/-size{K,M,G,T,P} (66048-123091886, default 123090943): +5g
Created a new partition 2 of type 'Linux filesystem' and of size 5 GiB.
Partition #2 contains a squashfs signature.
Do you want to remove the signature? [Y]es/[N]o: n
Command (m for help): p
Disk /dev/sda: 58.69 GiB, 63023063040 bytes, 123091920 sectors
Disk model: SanDisk SSD i110
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 20C60F33-AFC6-96E2-AE0B-E001AE609500
Device Start End Sectors Size Type
/dev/sda1 512 66047 65536 32M Linux filesystem
/dev/sda2 66048 10551295 10485248 5G Linux filesystem
/dev/sda128 34 511 478 239K BIOS boot
Partition table entries are not in disk order.
Command (m for help): w
The partition table has been altered.
Syncing disks.
root@ImmortalWrt:~# 4.检查新的分区表状态
1、使用fdisk -l列出所有磁盘上的分区表信息，我们看到磁盘分区表已经是5G的空间状态了
root@ImmortalWrt:~# fdisk -l
Disk /dev/loop0: 291.06 MiB, 305201152 bytes, 596096 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/sda: 58.69 GiB, 63023063040 bytes, 123091920 sectors
Disk model: SanDisk SSD i110
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 20C60F33-AFC6-96E2-AE0B-E001AE609500
Device Start End Sectors Size Type
/dev/sda1 512 66047 65536 32M Linux filesystem
/dev/sda2 66048 10551295 10485248 5G Linux filesystem
/dev/sda128 34 511 478 239K BIOS boot
Partition table entries are not in disk order.2、使用df -Th查看文件系统磁盘空间使用情况
root@ImmortalWrt:~# df -Th
Filesystem Type Size Used Available Use% Mounted on
/dev/root squashfs 9.0M 9.0M 0 100% /rom
tmpfs tmpfs 906.0M 1.1M 904.9M 0% /tmp
/dev/loop0 f2fs 289.1M 63.1M 226.0M 22% /overlay
overlayfs:/overlay overlay 289.1M 63.1M 226.0M 22% /
/dev/sda1 vfat 31.9M 7.9M 24.1M 25% /boot
/dev/sda1 vfat 31.9M 7.9M 24.1M 25% /boot
tmpfs tmpfs 512.0K 0 512.0K 0% /dev
/dev/sda1 vfat 31.9M 7.9M 24.1M 25% /mnt/sda1
root@ImmortalWrt:~# 我们看到，文件系统并没有正确识别到新分配的overlay的 / 根分区的空间，还是289.1M
5.查看当前挂载的循环设备状态
root@ImmortalWrt:~# losetup
NAME SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE DIO LOG-SEC
/dev/loop0 0 9371648 1 0 /sda2 0 512
root@ImmortalWrt:~# 结合df-Th命令我们看到，/ 这个挂载点使用了 overlay 文件系统技术，并且要记住“OFFSET的偏移量是9371648”，未来也要一致才可以！
loop 设备 /dev/loop0 被映射到了 /sda2 文件上，也就是说现在/sda2用overlay技术，挂载为/目录
总结
- 只读层：
/dev/root（类型为squashfs）。 - 可写层：
/overlay（类型为f2fs，通过/dev/loop0映射到/sda2文件）。 - 最终挂载点：
/（类型为overlay，整合了只读层和可写层）。
这就是为什么squashfs的文件系统可以有“恢复到出厂设置”功能，而ext4文件系统没法恢复的原理。（因为这个根目录既可以有只读层的数据，又有安装软件，修改配置文件的数据）
6.现在我们要重新挂载刚刚创建好的循环设备，以实现替换的目的
因为刚刚讲了这个/根目录是混合型的，必须精确指明哪里是只读的，哪里是可写的，所以这个“OFFSET的偏移量是9371648”
root@ImmortalWrt:~# losetup -f -o 9371648 /dev/sda2
root@ImmortalWrt:~# losetup
NAME SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE DIO LOG-SEC
/dev/loop1 0 9371648 0 0 /dev/sda2 0 512
/dev/loop0 0 9371648 1 0 /sda2 0 512
root@ImmortalWrt:~# 这里注意区别，/dev/sda2是分区，没有挂载具体位置，/sda2已经挂载在/根目录，
7.为了确保数据的一致性，我们先挂载一下数据，检查一下数据是否存在，在卸载释放资源。因为磁盘刚刚被全删除了，后面重启可能会丢失数据，这样做保险一些。
root@ImmortalWrt:~# mount /dev/loop1 /mnt
root@ImmortalWrt:~# tree -L 2 /mnt
/mnt
├── upper
│ ├── boot
│ ├── etc
│ ├── lib
│ ├── mnt
│ ├── sbin
│ └── usr
└── work
└── work
10 directories, 0 files
root@ImmortalWrt:~# umount /dev/loop18.确认挂载的循环设备的文件系统格式（是f2fs,还是）
root@ImmortalWrt:/# lsblk -f
NAME FSTYPE FSVER LABEL UUID FSAVAIL FSUSE% MOUNTPOINTS
loop0 f2fs rootfs_data 1858fcd6-7767-11ef-979c-5fec82ce50f5 225.9M 22% /overlay
loop1 f2fs rootfs_data 1858fcd6-7767-11ef-979c-5fec82ce50f5
sda
├─sda1 vfat kernel 1234-ABCD 24.1M 25% /mnt/sda1
│ /boot
│ /boot
├─sda2 squashfs 0 100% /rom
└─sda128
root@ImmortalWrt:/# 9.如果是f2fs的文件系统，执行扩容命令，刷新文件
root@ImmortalWrt:/# resize.f2fs -f /dev/loop1
Info: Force to resize
Info: MKFS version
"Linux version 5.15.162 (buildbot@buildbot.infra.immortalwrt.org) (x86_64-openwrt-linux-musl-gcc (OpenWrt GCC 12.3.0 r27917-81a1f98d5b) 12.3.0, GNU ld (GNU Binutils) 2.40.0) #0 SMP Thu Jul 18 06:35:54 2024"
Info: FSCK version
from "Linux version 5.15.162 (buildbot@buildbot.infra.immortalwrt.org) (x86_64-openwrt-linux-musl-gcc (OpenWrt GCC 12.3.0 r27917-81a1f98d5b) 12.3.0, GNU ld (GNU Binutils) 2.40.0) #0 SMP Thu Jul 18 06:35:54 2024"
to "Linux version 5.15.162 (buildbot@buildbot.infra.immortalwrt.org) (x86_64-openwrt-linux-musl-gcc (OpenWrt GCC 12.3.0 r27917-81a1f98d5b) 12.3.0, GNU ld (GNU Binutils) 2.40.0) #0 SMP Thu Jul 18 06:35:54 2024"
Info: superblock features = 0 :
Info: superblock encrypt level = 0, salt = 00000000000000000000000000000000
Info: Segments per section = 1
Info: Sections per zone = 1
Info: total FS sectors = 596096 (291 MB)
Info: CKPT version = 43a353a3
Info: Duplicate valid checkpoint to mirror position 512 -> 1024
Info: Write valid nat_bits in checkpoint
[FIX] (move_one_curseg_info:2921) --> Move curseg[0] 3 -> 10 after 2c00
[FIX] (move_one_curseg_info:2921) --> Move curseg[1] 6 -> 13 after 2c00
[FIX] (move_one_curseg_info:2921) --> Move curseg[2] 4 -> 11 after 2c00
[FIX] (move_one_curseg_info:2921) --> Move curseg[3] 0 -> e after 2c00
[FIX] (move_one_curseg_info:2921) --> Move curseg[4] 1 -> f after 2c00
[FIX] (move_one_curseg_info:2921) --> Move curseg[5] 2 -> 14 after 2c00
Info: Write valid nat_bits in checkpoint
Try to do defragement: Done
[migrate_ssa: 272] Info: Done to migrate SSA blocks: sum_blkaddr = 0xe00 -> 0x2200
[migrate_nat: 389] Info: Done to migrate NAT blocks: nat_blkaddr = 0xa00 -> 0xa00
[migrate_sit: 447] Info: Done to restore new SIT blocks: 0x600
[rebuild_checkpoint: 486] Info: Overprovision ratio = 2.150%
[rebuild_checkpoint: 487] Info: Overprovision segments = 55 (GC reserved = 53)
Info: Write valid nat_bits in checkpoint
[rebuild_checkpoint: 603] Info: Done to rebuild checkpoint blocks
[update_superblock: 765] Info: Done to update superblock
Done: 0.799958 secs
root@ImmortalWrt:/# 10.如果是ext4文件系统，执行扩容命令，刷新文件
root@ImmortalWrt:/# resize2fs -f /dev/loop1
resize2fs 1.46.5 (30-Dec-2021)
Filesystem at /dev/sdb1 is mounted on /overlay; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 24
The filesystem on /dev/loop1 is now 52428539 (4k) blocks long.11.扩容后，重启前的最后一件重要的事（有EFI引导的要注意）
如果你的固件是带efi的
# 带-efi的
immortalwrt-23.05.3-x86-64-generic-squashfs-combined-efi.img
immortalwrt-23.05.3-x86-64-generic-ext4-combined-efi.img
# 不带-efi的
immortalwrt-23.05.3-x86-64-generic-squashfs-combined.img
immortalwrt-23.05.3-x86-64-generic-ext4-combined.img确认你的uuid，是sda2的PARTUUID="cfd7abf3-cf18-4a4a-95e4-46f2013c080f"，
root@ImmortalWrt:/# blkid
/dev/loop1: LABEL="rootfs_data" UUID="1858fcd6-7767-11ef-979c-5fec82ce50f5" BLOCK_SIZE="4096" TYPE="f2fs"
/dev/loop0: LABEL="rootfs_data" UUID="1858fcd6-7767-11ef-979c-5fec82ce50f5" BLOCK_SIZE="4096" TYPE="f2fs"
/dev/sda2: BLOCK_SIZE="262144" TYPE="squashfs" PARTUUID="cfd7abf3-cf18-4a4a-95e4-46f2013c080f"
/dev/sda128: PARTUUID="20c60f33-afc6-96e2-ae0b-e001ae609580"
/dev/sda1: SEC_TYPE="msdos" LABEL_FATBOOT="kernel" LABEL="kernel" UUID="1234-ABCD" BLOCK_SIZE="512" TYPE="vfat" PARTUUID="20c60f33-afc6-96e2-ae0b-e001ae609501"
root@ImmortalWrt:/# 并修改你的系统启动引导
root@ImmortalWrt:/# vim /boot/grub/grub.cfg 把里面的2个uuid都改成，sda2的PARTUUID cfd7abf3-cf18-4a4a-95e4-46f2013c080f
root@ImmortalWrt:/# cat /boot/grub/grub.cfg
serial --unit=0 --speed=115200 --word=8 --parity=no --stop=1 --rtscts=off
terminal_input console serial; terminal_output console serial
set default="0"
set timeout="3"
search -l kernel -s root
menuentry "ImmortalWrt" {
linux /boot/vmlinuz root=PARTUUID=cfd7abf3-cf18-4a4a-95e4-46f2013c080f rootwait console=tty0 console=ttyS0,115200n8 noinitrd
}
menuentry "ImmortalWrt (failsafe)" {
linux /boot/vmlinuz failsafe=true root=PARTUUID=cfd7abf3-cf18-4a4a-95e4-46f2013c080f rootwait console=tty0 console=ttyS0,115200n8 noinitrd
}
root@ImmortalWrt:/# 12.执行reboot，重启后生效，检查最后的分区成果！
BusyBox v1.36.1 (2024-07-18 06:35:54 UTC) built-in shell (ash)
.___ __ .__
| | _____ _____ ____________/ |______ | |
| |/ \ / \ / _ \_ __ \ __\__ \ | |
| | Y Y \ Y Y ( <_> ) | \/| | / __ \| |__
|___|__|_| /__|_| /\____/|__| |__| (____ /____/
\/ \/ BE FREE AND UNAFRAID \/
-----------------------------------------------------
ImmortalWrt 23.05.3, r27917-81a1f98d5b
-----------------------------------------------------
root@ImmortalWrt:~# df -Th
Filesystem Type Size Used Available Use% Mounted on
/dev/root squashfs 9.0M 9.0M 0 100% /rom
tmpfs tmpfs 906.0M 104.0K 905.9M 0% /tmp
/dev/loop0 f2fs 5.0G 162.8M 4.8G 3% /overlay
overlayfs:/overlay overlay 5.0G 162.8M 4.8G 3% /
tmpfs tmpfs 512.0K 0 512.0K 0% /dev
/dev/sda1 vfat 31.9M 7.9M 24.1M 25% /mnt/sda1
root@ImmortalWrt:~# 我们可以看到，可用空间已经变成了5G,大功告成。
13.有EFI引导的，必须修改引导，没有EFI引导的（传统bios引导的，这取决你当时安装的是什么版本），可以跳过这步，直接reboot，重启后就扩容成功了。
没有efi引导的扩容过程如下ext4文件系统扩容，先摆这里，暂时无时间整理
建议安装的软件
lsblk
fdisk
losetup
resize2fs
tree可选装的软件（openwrt官方源不提供diskman）
diskman查看磁盘分区
root@OpenWrt:~# fdisk -l
Disk /dev/loop0: 99.81 MiB, 104660992 bytes, 204416 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/sda: 58.69 GiB, 63023063040 bytes, 123091920 sectors
Disk model: SanDisk SSD i110
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x95a30341
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 512 33279 32768 16M 83 Linux
/dev/sda2 33792 246783 212992 104M 83 Linux
root@OpenWrt:~# 删除sda2分区，重新创建一个10G的sda2（开始位置一定是p打印出来的sda2的原始的那个start值33792），不能删除标识符选N，一个也不能错！
root@OpenWrt:~# fdisk /dev/sda
Welcome to fdisk (util-linux 2.39).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
This disk is currently in use - repartitioning is probably a bad idea.
It's recommended to umount all file systems, and swapoff all swap
partitions on this disk.
Command (m for help): p
Disk /dev/sda: 58.69 GiB, 63023063040 bytes, 123091920 sectors
Disk model: SanDisk SSD i110
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x95a30341
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 512 33279 32768 16M 83 Linux
/dev/sda2 33792 246783 212992 104M 83 Linux
Command (m for help): d
Partition number (1,2, default 2): 2
Partition 2 has been deleted.
Command (m for help): n
Partition type
p primary (1 primary, 0 extended, 3 free)
e extended (container for logical partitions)
Select (default p): p
Partition number (2-4, default 2): 2
First sector (33280-123091919, default 34816): 33792
Last sector, +/-sectors or +/-size{K,M,G,T,P} (33792-123091919, default 123091919): +10g
Created a new partition 2 of type 'Linux' and of size 10 GiB.
Partition #2 contains a squashfs signature.
Do you want to remove the signature? [Y]es/[N]o: n
Command (m for help): p
Disk /dev/sda: 58.69 GiB, 63023063040 bytes, 123091920 sectors
Disk model: SanDisk SSD i110
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x95a30341
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 512 33279 32768 16M 83 Linux
/dev/sda2 33792 21006335 20972544 10G 83 Linux
Command (m for help): w
The partition table has been altered.
Syncing disks.
root@OpenWrt:~# 再次验证
root@OpenWrt:~# fdisk -l
Disk /dev/loop0: 99.81 MiB, 104660992 bytes, 204416 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk /dev/sda: 58.69 GiB, 63023063040 bytes, 123091920 sectors
Disk model: SanDisk SSD i110
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x95a30341
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 512 33279 32768 16M 83 Linux
/dev/sda2 33792 21006335 20972544 10G 83 Linux
root@OpenWrt:~# 我们可以看到，还是磁盘分区表信息中已经是10G的空间状态了
root@OpenWrt:~# df -Th
Filesystem Type Size Used Available Use% Mounted on
/dev/root squashfs 4.3M 4.3M 0 100% /rom
tmpfs tmpfs 910.1M 1.0M 909.1M 0% /tmp
/dev/loop0 ext4 88.0M 2.2M 78.8M 3% /overlay
overlayfs:/overlay overlay 88.0M 2.2M 78.8M 3% /
/dev/sda1 ext4 15.7M 5.6M 9.8M 36% /boot
/dev/sda1 ext4 15.7M 5.6M 9.8M 36% /boot
tmpfs tmpfs 512.0K 0 512.0K 0% /dev
root@OpenWrt:~# 我们可以看到，文件系统并没有正确识别到新分配的overlay的 / 根分区的空间，还是88.0M，所以此时我们还需要重启（没有-efi的固件）
root@OpenWrt:~# reboot
root@OpenWrt:~# Connection closing...Socket close.
Connection closed by foreign host.
Disconnected from remote host(192.168.1.1) at 11:37:14.执行reboot重启后，查看一下挂载点，确认是
root@OpenWrt:~# losetup
NAME SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE
DIO LOG-SEC
/dev/loop0 0 4390912 1 0 /sda2 0 512
root@OpenWrt:~# 查看下磁盘空间，依旧没有识别
root@OpenWrt:~# df -Th
Filesystem Type Size Used Available Use% Mounted on
/dev/root squashfs 4.3M 4.3M 0 100% /rom
tmpfs tmpfs 910.1M 84.0K 910.1M 0% /tmp
/dev/loop0 ext4 88.0M 2.2M 78.8M 3% /overlay
overlayfs:/overlay overlay 88.0M 2.2M 78.8M 3% /
/dev/sda1 ext4 15.7M 5.6M 9.8M 36% /boot
/dev/sda1 ext4 15.7M 5.6M 9.8M 36% /boot
tmpfs tmpfs 512.0K 0 512.0K 0% /dev
root@OpenWrt:~# 但是没关系，最后执行一次扩容命令即可，扩容成功！
root@OpenWrt:~# resize2fs -f /dev/loop0
resize2fs 1.47.0 (5-Feb-2023)
Filesystem at /dev/loop0 is mounted on /overlay; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 80
The filesystem on /dev/loop0 is now 10481984 (1k) blocks long.
root@OpenWrt:~# 最后检查一遍文件系统空间
root@OpenWrt:~# df -Th
Filesystem Type Size Used Available Use% Mounted on
/dev/root squashfs 4.3M 4.3M 0 100% /rom
tmpfs tmpfs 910.1M 84.0K 910.1M 0% /tmp
/dev/loop0 ext4 9.4G 2.2M 9.0G 0% /overlay
overlayfs:/overlay overlay 9.4G 2.2M 9.0G 0% /
/dev/sda1 ext4 15.7M 5.6M 9.8M 36% /boot
/dev/sda1 ext4 15.7M 5.6M 9.8M 36% /boot
tmpfs tmpfs 512.0K 0 512.0K 0% /dev
root@OpenWrt:~# 我们可以看到，文件系统已经正确识别到新分配的overlay的 / 根分区的空间已经是9.4G了，扩容成功！
分享结束！
