OpenWRT wfopen «Read-only file system.»

root@OpenWrt-router82:~# opkg update
Downloading http://downloads.openwrt.org/releases/19.07.5/targets/brcm47xx/legacy/packages/Packages.gz
Updated list of available packages in /var/opkg-lists/openwrt_core
...
Downloading http://downloads.openwrt.org/releases/19.07.5/packages/mipsel_mips32/telephony/Packages.sig
Signature check passed.
root@OpenWrt-router82:~#

root@OpenWrt-router82:~# opkg install kmod-usb-storage
Installing kmod-usb-storage (4.14.209-1) to root...
Downloading http://downloads.openwrt.org/releases/19.07.5/targets/brcm47xx/legacy/kmods/4.14.209-1-fb579c7d7b3b1d27d979ba1ec8153d20/kmod-usb-storage_4.14.209-1_mipsel_mips32.ipk
Installing kmod-scsi-core (4.14.209-1) to root...
Downloading http://downloads.openwrt.org/releases/19.07.5/targets/brcm47xx/legacy/kmods/4.14.209-1-fb579c7d7b3b1d27d979ba1ec8153d20/kmod-scsi-core_4.14.209-1_mipsel_mips32.ipk
Collected errors:
* wfopen: //usr/lib/opkg/info/kmod-scsi-core.control: Read-only file system.
* wfopen: //usr/lib/opkg/info/kmod-scsi-core.postinst: Read-only file system.
* wfopen: //usr/lib/opkg/info/kmod-scsi-core.prerm: Read-only file system.
* extract_archive: Cannot create symlink from ./etc/modules-boot.d/40-scsi-core to '../modules.d/40-scsi-core': Read-only file system.
* wfopen: /etc/modules.d/40-scsi-core: Read-only file system.
* wfopen: /lib/modules/4.14.209/scsi_mod.ko: Read-only file system.
* wfopen: /lib/modules/4.14.209/sd_mod.ko: Read-only file system.
* pkg_write_filelist: Failed to open //usr/lib/opkg/info/kmod-scsi-core.list: Read-only file system.
* opkg_install_pkg: Failed to extract data files for kmod-scsi-core. Package debris may remain!
* opkg_install_cmd: Cannot install package kmod-usb-storage.
root@OpenWrt-router82:~#

root@OpenWrt-router82:~# mount
/dev/root on /rom type squashfs (ro,relatime)
proc on /proc type proc (rw,nosuid,nodev,noexec,noatime)
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,noatime)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev,noatime)
/dev/mtdblock5 on /overlay type jffs2 (rw,noatime)
overlayfs:/overlay on / type overlay (ro,noatime,lowerdir=/,upperdir=/overlay/upper,workdir=/overlay/work)
tmpfs on /dev type tmpfs (rw,nosuid,relatime,size=512k,mode=755)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,mode=600,ptmxmode=000)
debugfs on /sys/kernel/debug type debugfs (rw,noatime)
root@OpenWrt-router82:~#

root@OpenWrt-router82:/# du -shx *
0 bin
0 dev
0 etc
0 lib
0 mnt
7.6M overlay
0 proc
7.9M rom
0 root
0 sbin
0 sys
936.0K tmp
0 usr
0 var
0 www
root@OpenWrt-router82:/#

root@OpenWrt-router82:/# df -h
Filesystem Size Used Available Use% Mounted on
/dev/root 2.6M 2.6M 0 100% /rom
tmpfs 13.8M 936.0K 12.8M 7% /tmp
/dev/mtdblock5 3.9M 3.9M 88.0K 98% /overlay
overlayfs:/overlay 3.9M 3.9M 88.0K 98% /
tmpfs 512.0K 0 512.0K 0% /dev
root@OpenWrt-router82:/# mount
/dev/root on /rom type squashfs (ro,relatime)
proc on /proc type proc (rw,nosuid,nodev,noexec,noatime)
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,noatime)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev,noatime)
/dev/mtdblock5 on /overlay type jffs2 (rw,noatime)
overlayfs:/overlay on / type overlay (ro,noatime,lowerdir=/,upperdir=/overlay/upper,workdir=/overlay/work)
tmpfs on /dev type tmpfs (rw,nosuid,relatime,size=512k,mode=755)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,mode=600,ptmxmode=000)
debugfs on /sys/kernel/debug type debugfs (rw,noatime)
root@OpenWrt-router82:/#