BCF-6552: [REAR] REAR tries to map the disk that has been commented in the disklayout.conf file on the source machine

[Barys Barysenka (BarysBarysenka)]

prevent failure when mapping excluded disks in df.txt

[Copilot]

Pull request overview

Adjusts ReaR’s migration-mode layout mapping step to avoid aborting recovery when df.txt contains references to disks that were excluded/commented out in the source layout, while keeping strict failures for core layout/config files.

Changes:

• Treat failures applying layout mappings to $VAR_DIR/layout/config/df.txt as a warning (do not fail the overall mapping step).
• Keep hard-failure behavior for disklayout.conf ($LAYOUT_FILE) and /etc/rear/rescue.conf.

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[Copilot]

The codebase consistently prefixes warning-level user messages with "WARNING:" (often using LogPrint), but this message uses "Warning:". Consider changing it to match existing wording/format (e.g., "WARNING: Failed …"), to keep log scanning/grep behavior consistent.

Suggested change

	LogPrint "Warning: Failed to apply disk layout mappings to $file_to_migrate (likely due to unmapped excluded disks)."
	LogPrint "WARNING: Failed to apply disk layout mappings to $file_to_migrate (likely due to unmapped excluded disks)."

[Copilot]

The warning text asserts a specific root cause ("likely due to unmapped excluded disks"), but this isn't actually checked here and could mislead troubleshooting if apply_layout_mappings failed for another reason. Consider rephrasing to a more factual message (e.g., that failure is being ignored for df.txt because it may include excluded devices).

Suggested change

	LogPrint "Warning: Failed to apply disk layout mappings to $file_to_migrate (likely due to unmapped excluded disks)."
	LogPrint "Warning: Failed to apply disk layout mappings to $file_to_migrate; continuing without mappings for this file (it may include excluded devices)."

[Andrus Suvalau (svlv)]

original_disk_space_usage_file is used in 420_autoresize_last_partitions.sh to calculate last_part_used_bytes.

It means that disk layout mapping must be applied to original_disk_space_usage_file at least to check the original disk space usage when it is necessary.

What does original_disk_space_usage_file contain in case of error?

E.g. the original system has /dev/sda which is not used and /dev/sdb which is used, next, during recovery /dev/sdb is mapped to /dev/sda; what will original_disk_space_usage_file look like after failure? Will it contain two entries for /dev/sda?

[Andrus Suvalau (svlv)]

The issue is related to AUTOEXCLUDE_PATH and df.txt: auto-excluded disks are commented out in disklayout.conf but are not commented out in df.txt

Steps to reproduce:

1. Use, e.g., /tmp/disk1 as mount point (/tmp is in AUTOEXCLUDE_PATH; please note, that /mnt is not in AUTOEXCLUDE_PATH in Cove by default):
   mkfs.ext4 /dev/sda; mkdir /tmp/disk1; mount /dev/sda /tmp/disk1;
2. Do backup and check the df.txt file:
   E.g., on my test machine running RHEL 10, df.txt contains the following lines:

Filesystem            1048576-blocks   Used Available Capacity Mounted on
/dev/mapper/rhel-root         25956M 10324M    15633M      40% /
efivarfs                          1M     1M        1M      23% /sys/firmware/efi/efivars
/dev/sdb2                       960M   580M      381M      61% /boot
/dev/sdb1                       599M     9M      591M       2% /boot/efi
/dev/sda                        974M     1M      907M       1% /tmp/disk2

Note, /dev/sda is not commented out.
However, in disklayout.conf /dev/sda and fs on /dev/sda are commented out:

...
#disk /dev/sda 1073741824 loop
...
#fs /dev/sda /tmp/disk2 ext4 uuid=2dfab626-638a-42c6-bf60-c3cab3368ff4 label= blocksize=4096 reserved_blocks=4% max_mounts=-1 check_interval=0d bytes_per_inode=16384 default_mount_options=user_xattr,acl options=rw,relatime,seclabel

3. Do migration
   The error is:

Failed to apply layout mappings to /tmp/rear/var/lib/rear/layout/config/df.txt for /dev/sda (probably no mapping for /dev/sda in /tmp/rear/var/lib/rear/layout/disk_mappings)
Failed to apply disk layout mappings to /tmp/rear/var/lib/rear/layout/config/df.txt

df.txt contains the following lines:

Filesystem            1048576-blocks   Used Available Capacity Mounted on
/dev/mapper/rhel-root         25956M 10324M    15633M      40% /
efivarfs                          1M     1M        1M      23% /sys/firmware/efi/efivars
/dev/sda2                       960M   580M      381M      61% /boot
/dev/sda1                       599M     9M      591M       2% /boot/efi
_REAR1_                        974M     1M      907M       1% /tmp/disk2

Likely 320_autoexclude.sh which is responsible for auto-exclude must respect and comment out information df.txt as it is done for LAYOUT_FILE .

[Andrus Suvalau (svlv)]

Do we still need this change?

[Andrus Suvalau (svlv)]

The answer was - yes, we need it for backup sessions done earlier (without the fix in the PR).

[Andrus Suvalau (svlv)]

It is a broken sed expression.

You are using sed s/search/replace/flags form here.

[] in the search part is the bracket expression, see Classes and Bracket Expressions.

If you want to use it correctly, you need to use [][\/$*.^,] in the search part.
See How do i replace [] brackets using SED for more detail.

Suggested change

	mp_pattern=$( echo "$mountpoint" | sed 's/[]\/$*.^[],]/\\&/g' )
	mp_pattern=$( echo "$mountpoint" | sed 's/[][\/$*.^,]/\\&/g' )