incusd/storage/zfs: Rework zvol resolution logic#2673
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Signed-off-by: Stéphane Graber <[email protected]>
The previous logic was relying either on udev or on a slow crawl through /dev using the zvol_id utility. This was problematic not just because we could get into timeouts on systems with a LOT of volumes, but also because it was inherently racy. Udev works in the background, so entries may not show up immediately and if something goes wrong during cleanup, we can be left with a symlink pointing to the wrong /dev/zdXYZ device. This is very similar to the LVM issue we fixed a little while back where in the worst case scenario, it can lead to the wrong block device being accessed, causing corruption or potential data leakage. The new logic relies entirely on devtmpfs (not udev) and is optimized to try and hit the correct /dev/zdXYZ device almost immediately, limiting the performance impact on busy systems. Closes lxc#1505 Signed-off-by: Stéphane Graber <[email protected]>
This reverts commit ae53328. Signed-off-by: Stéphane Graber <[email protected]>
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…ncus) (#17095) Cherry-picks from lxc/incus#2673
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The previous logic was relying either on udev or on a slow crawl through /dev using the zvol_id utility.
This was problematic not just because we could get into timeouts on systems with a LOT of volumes, but also because it was inherently racy. Udev works in the background, so entries may not show up immediately and if something goes wrong during cleanup, we can be left with a symlink pointing to the wrong /dev/zdXYZ device.
This is very similar to the LVM issue we fixed a little while back where in the worst case scenario, it can lead to the wrong block device being accessed, causing corruption or potential data leakage.
The new logic relies entirely on devtmpfs (not udev) and is optimized to try and hit the correct /dev/zdXYZ device almost immediately, limiting the performance impact on busy systems.
Closes #1505