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Description of problem:
If a vdo has a logical size which is an exact multiple of 821 4K blocks, a read-only rebuild will fail to rebuild the reference counts for any of the final 821 logical blocks of the volume.

Version-Release number of selected component (if applicable):


How reproducible:
With certainty.

Steps to Reproduce:
1. Create a vdo volume whose logical size is an exact multiple of 821 4K blocks.
2. Write some non-zero data to (some of) the last 821 blocks of the volume.
3. Stop the device.
4. Run vdoreadonly to but the vdo into read-only mode.
5. Run vdoforcerebuild to request a rebuild on the next start.
6. Start the device.
7. Overwrite the data written in step 2.

Actual results:
The vdo goes into read-only mode with a reference count error.

Expected results:
The vdo continues to function normally.

Additional info:

Verified with kmod-kvdo-6.2.8.7-88.el8.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (kmod-kvdo bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2023:2957