extend-filesystems: Fix race condition by not using lsblk#132
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chewi merged 1 commit intoflatcar-masterfrom Jun 12, 2025
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extend-filesystems: Fix race condition by not using lsblk#132chewi merged 1 commit intoflatcar-masterfrom
chewi merged 1 commit intoflatcar-masterfrom
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jepio
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Jun 12, 2025
lsblk relies on udev, which is inherently racy, especially when the filesystem has just been mounted. It has been observed that the FSTYPE field is sometimes not populated, preventing the filesystem from being resized, and causing tests involving the dev container (which is large) to fail. Use findmnt instead, which gets its information directly from the kernel. It also natively supports filtering by filesystem type and mount option. It doesn't fetch PARTTYPE, but we can safely get that from cgpt. Signed-off-by: James Le Cuirot <jlecuirot@microsoft.com>
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An associated Kola fix is included. Closes: flatcar/init#132 Closes: flatcar/Flatcar#296 Signed-off-by: James Le Cuirot <jlecuirot@microsoft.com>
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extend-filesystems: Fix race condition by not using lsblk
lsblk relies on udev, which is inherently racy, especially when the filesystem has just been mounted. It has been observed that the
FSTYPEfield is sometimes not populated, preventing the filesystem from being resized, and causing tests involving the dev container (which is large) to fail.Use findmnt instead, which gets its information directly from the kernel. It also natively supports filtering by filesystem type and mount option. It doesn't fetch
PARTTYPE, but we can safely get that from cgpt.This could be quite an important fix. We have only seen test failures so far, and maybe that's because it only triggers when the system is under load, but I see no reason why it wouldn't happen in production. Perhaps this only started breaking recently following an update to the kernel or udev or something.
How to use
Check that the extend-filesystems.service unit works successfully and that / is actually resized.
Testing done
CI has passed. I previously forced the test to fail so that it would retry and I could see the output. Once I had applied the fix, it would successfully resize every time, whereas before it would fail most of the time.