Fix error handling in FreeBSD's get/putpages VOPs #13311

markjdb · 2022-04-09T15:50:00Z

Motivation and Context

In FreeBSD, most VOPs return errno values to signal an error, but a couple that are used by the VM system expect Mach error codes, owing to the fact that that subsystem was ported from Mach. Currently VOP_GET/PUTPAGES will return EIO if ZFS_ENTER() fails, and this violates some invariants in the VM system.

Description

The change adds variants of the ZFS_ENTER() and ZFS_VERIFY_ZP() macros which allow the user to specify a return value. Then it converts VOP_GETPAGES and VOP_PUTPAGES to make use of these variants to return Mach error statuses.

How Has This Been Tested?

We have a stress test which was able to trigger a panic based on this bug: https://github.com/freebsd/freebsd-src/blob/main/tools/test/stress2/misc/zfs14.sh

With the patch, it runs for hours without any observed problems.

Types of changes

Bug fix (non-breaking change which fixes an issue)
New feature (non-breaking change which adds functionality)
Performance enhancement (non-breaking change which improves efficiency)
Code cleanup (non-breaking change which makes code smaller or more readable)
Breaking change (fix or feature that would cause existing functionality to change)
Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
Documentation (a change to man pages or other documentation)

Checklist:

My code follows the OpenZFS code style requirements.
I have updated the documentation accordingly.
I have read the contributing document.
I have added tests to cover my changes.
I have run the ZFS Test Suite with this change applied.
All commit messages are properly formatted and contain Signed-off-by.

For legacy reasons, a couple of VOPs have to return error numbers that don't come from the usual errno namespace. To handle the cases where ZFS_ENTER or ZFS_VERIFY_ZP fail, we need to be able to override the default error return value of EIO. Extend the macros to permit this. Signed-off-by: Mark Johnston <[email protected]>

FreeBSD's memory management system uses its own error numbers and gets confused when these VOPs return EIO. Reported-by: Peter Holm <[email protected]> Signed-off-by: Mark Johnston <[email protected]>

FreeBSD's memory management system uses its own error numbers and gets confused when these VOPs return EIO. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Ryan Moeller <[email protected]> Reported-by: Peter Holm <[email protected]> Signed-off-by: Mark Johnston <[email protected]> Closes #13311

For legacy reasons, a couple of VOPs have to return error numbers that don't come from the usual errno namespace. To handle the cases where ZFS_ENTER or ZFS_VERIFY_ZP fail, we need to be able to override the default error return value of EIO. Extend the macros to permit this. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Ryan Moeller <[email protected]> Signed-off-by: Mark Johnston <[email protected]> Closes openzfs#13311

FreeBSD's memory management system uses its own error numbers and gets confused when these VOPs return EIO. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Ryan Moeller <[email protected]> Reported-by: Peter Holm <[email protected]> Signed-off-by: Mark Johnston <[email protected]> Closes openzfs#13311

For legacy reasons, a couple of VOPs have to return error numbers that don't come from the usual errno namespace. To handle the cases where ZFS_ENTER or ZFS_VERIFY_ZP fail, we need to be able to override the default error return value of EIO. Extend the macros to permit this. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Ryan Moeller <[email protected]> Signed-off-by: Mark Johnston <[email protected]> Closes #13311