** Also affects: linux (Ubuntu Eoan)
Importance: Undecided
Assignee: Mauricio Faria de Oliveira (mfo)
Status: Invalid
** Also affects: linux (Ubuntu Disco)
Importance: Undecided
Status: New
** Changed in: linux (Ubuntu Disco)
Status: New => In Progress
** Changed in: linux (Ubuntu Eoan)
Status: Invalid => In Progress
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https://bugs.launchpad.net/bugs/1829563
Title:
bcache: risk of data loss on I/O errors in backing or caching devices
Status in linux package in Ubuntu:
In Progress
Status in linux source package in Bionic:
In Progress
Status in linux source package in Cosmic:
In Progress
Status in linux source package in Disco:
In Progress
Status in linux source package in Eoan:
In Progress
Bug description:
[Impact]
* The bcache code in Bionic lacks several fixes to handle
I/O errors in both backing devices and caching devices.
* Partial or permanent errors in backing or caching devices,
specially in writeback mode, can lead to data loss and/or
the application is not notified about failed I/O requests.
* The bcache device might remain available for I/O requests
even if backing device is offline, so writes are undefined.
[Test Case]
* Detailed test cases/steps for the behavior of many patches
with code logic changes are provided in bug comments.
* The patchset has been tested for regressions on each cache
mode (writethrough, writeback, writearound, none) with the
xfstests test suite (on ext4) and fio (sequential + random
read-write).
[Regression Potential]
* The patchset is relatively large and touches several areas
in bcache code, however, synthetic testing of the patches
has been performed, and extensive regression/stress tests
were run (as mentioned in Test Case section).
* Many patches in the patchset are 'Fixes' patches to other
patches, and no further 'Fixes' currently exist upstream.
[Other Info]
* Canonical Field Eng. deploys bcache+writeback extensively
(e.g., BootStack, UA cloud, except rare all-flash cases).
[Original Bug Description]
This is a request for a backport of the following upstream patch from
4.18:
"bcache: stop bcache device when backing device is offline"
https://github.com/torvalds/linux/commit/0f0709e6bfc3ce4e8e1c0e8573490c45f76cfeee
Field engineering uses bcache quite extensively and it would be good
to have this in the GA/bionic kernel.
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