From: Yu Watanabe <watanabe.yu+github@gmail.com>
Date: Fri, 30 Jan 2026 06:36:03 +0000 (+0900)
Subject: Fix bug in DM iteration and standardise how to iterate through DM layers (#40426)
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1d60b723a30d00a2ccb21b12e84847f93ff9a933;p=thirdparty%2Fsystemd.git

Fix bug in DM iteration and standardise how to iterate through DM layers (#40426)

get_block_device_harder_fd() currently only traverses one level of
device mapper stacking when looking for the underlying block device.
This causes issues with nested DM setups like dm-crypt on top of
dm-integrity, where we don't traverse enough to get the actual physical
device.

Fix this by iterating through all DM layers until we reach a device with
no underlying device. And while we're at it also make cgroups use the
same logic.

Fixes: #40419
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1d60b723a30d00a2ccb21b12e84847f93ff9a933