[FS#1522] block-mount: external overlay filesystem not checked at boot

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - Andreas (ndvour) 

Attached to Project - OpenWrt/LEDE Project
Summary - block-mount: external overlay filesystem not checked at boot
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Medium
Priority - Very Low
Reported Version - lede-17.01
Due in Version - Undecided
Due Date - Undecided
Details - Environment: arm_cortex-a9_vfpv3, Linksys WRT1200AC, LEDE Reboot 17.01.4 r3560-79f57e422d

Description:
A USB flash drive has been configured with an ext4 partition to be used as external overlay, following the steps at https://openwrt.org/docs/guide-user/additional-software/extroot_configuration precisely. /etc/config/fstab has been further modified to perform a filesystem check on this partition when mounting. After rebooting, the logs show that the check is not being performed:
Sat Apr 28 12:24:51 2018 user.err kernel: [    7.522968] block: check_filesystem: /usr/sbin/e2fsck not found
Since the /usr/sbin/e2fsck binary //is// present in the //boot// overlay, the system should be able to perform the check as expected (maybe by calling e2fsck //before// and not after initiating the extroot switch?). Surrounding log messages follow:
Sat Apr 28 12:24:51 2018 user.info kernel: [    6.976787] mount_root: loading kmods from internal overlay
Sat Apr 28 12:24:51 2018 user.info kernel: [    6.992581] kmodloader: loading kernel modules from /tmp/overlay/upper/etc/modules-boot.d/*
Sat Apr 28 12:24:51 2018 kern.notice kernel: [    7.017551] sd 2:0:0:0: [sdb] 31326208 512-byte logical blocks: (16.0 GB/14.9 GiB)
Sat Apr 28 12:24:51 2018 kern.notice kernel: [    7.025923] sd 2:0:0:0: [sdb] Write Protect is off
Sat Apr 28 12:24:51 2018 kern.debug kernel: [    7.025927] sd 2:0:0:0: [sdb] Mode Sense: 43 00 00 00
Sat Apr 28 12:24:51 2018 kern.notice kernel: [    7.026668] sd 2:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
Sat Apr 28 12:24:51 2018 kern.info kernel: [    7.039577]  sdb: sdb1 sdb2
Sat Apr 28 12:24:51 2018 kern.notice kernel: [    7.049794] sd 2:0:0:0: [sdb] Attached SCSI removable disk
Sat Apr 28 12:24:51 2018 user.info kernel: [    7.150129] kmodloader: done loading kernel modules from /tmp/overlay/upper/etc/modules-boot.d/*
Sat Apr 28 12:24:51 2018 user.info kernel: [    7.514590] block: attempting to load /tmp/ubifs_cfg/upper/etc/config/fstab
Sat Apr 28 12:24:51 2018 user.err kernel: [    7.522968] block: check_filesystem: /usr/sbin/e2fsck not found
Sat Apr 28 12:24:51 2018 kern.warn kernel: [    8.034002] EXT4-fs (sdb1): warning: maximal mount count reached, running e2fsck is recommended
Sat Apr 28 12:24:51 2018 kern.info kernel: [    8.048213] EXT4-fs (sdb1): recovery complete
Sat Apr 28 12:24:51 2018 kern.info kernel: [    8.056919] EXT4-fs (sdb1): mounted filesystem with ordered data mode. Opts: 
Sat Apr 28 12:24:51 2018 kern.notice kernel: [    8.123434] UBIFS (ubi0:1): un-mount UBI device 0
Sat Apr 28 12:24:51 2018 kern.notice kernel: [    8.128168] UBIFS (ubi0:1): background thread "ubifs_bgt0_1" stops
Sat Apr 28 12:24:51 2018 user.info kernel: [    8.135302] mount_root: switched to extroot

More information can be found at the following URL:
https://bugs.openwrt.org/index.php?do=details&task_id=1522