Bug 2223896

Summary: ReaR fails to create the rescue environment when a device is shrinking while being read
Product: Red Hat Enterprise Linux 7 Reporter: Renaud Métrich <rmetrich>
Component: rearAssignee: Pavel Cahyna <pcahyna>
Status: ASSIGNED --- QA Contact: CS System Management SST QE <rhel-cs-system-management-subsystem-qe>
Severity: medium Docs Contact:
Priority: medium    
Version: 7.9CC: ovasik, pcahyna
Target Milestone: rcFlags: pcahyna: needinfo? (rmetrich)
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Hardware: All   
OS: Linux   
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Bug Depends On: 2223895    
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Description Renaud Métrich 2023-07-19 08:31:38 UTC 
This bug was initially created as a copy of Bug #2223895

I am copying this bug because: 

Also applies

Description of problem:

A customer hit an issue when building the ReaR ISO: the process always fails due to having a `/dev/mqueue/nnsc` which shrinks when being read, causing the verification code to (hopefully) fail.
See PR https://github.com/rear/rear/pull/3027 for details and a reproducer.

Version-Release number of selected component (if applicable):

all rear releases

How reproducible:

Always using the attached reproducer `shrinking.stp`

Steps to Reproduce:

1. Create a file in /dev which will be embedded in the rescue environment

    # dd if=/dev/urandom of=/dev/shrinking bs=10K count=3
    3+0 records in
    3+0 records out
    30720 bytes (31 kB, 30 KiB) copied, 0.000689566 s, 44.5 MB/s

2. Execute the systemtap script in charge of shrinking the file while being copied

    # yum -y install systemtap yum-utils
    # stap-prep
    # stap -v -g ./shrinking.stp
    [...]
    Pass 5: starting run.

3. Execute rear mkrescue from another terminal

    # rear mkrescue

Actual results:

ERROR: ReaR recovery system in '/var/tmp/rear.tpfZyNy6ayS53wP/rootfs' not usable (required libraries are missing)
Some latest log messages since the last called script 990_verify_rootfs.sh:
  wipefs is /bin/wipefs
  mkfs is /bin/mkfs
  mkfs.xfs is /bin/mkfs.xfs
  xfs_admin is /bin/xfs_admin
  mkswap is /bin/mkswap
  cryptsetup is /bin/cryptsetup
  dmsetup is /bin/dmsetup
  ldconfig is /bin/ldconfig

Expected results:

No error