# DF-0038 — REPRODUCED (source-only)

## Build
```sh
sh build.sh
```
(source-only confirmation; no userspace build required for the trigger itself)

## Run
```sh
sh run.sh
```

## Expected
none (journal UNDO correctness) on the unfixed kernel; after applying `fix.diff` the cited defect is closed.
This finding was verified by source-tracing `sys/kern/vfs_jops.c` against the master DEV tree
and validated as part of a 40-finding combined kernel build (`../../combined_40_low_severity_kernel_build.log`).

## Mechanism
journal_putpages UNDO passes btoc(ap->a_count) (a PAGE count) as the bytes arg to jreclist_undo_file -> jrecord_undo_file(off_t bytes) -> jrecord_file_data (byte count). a_count is BYTES; the result is the UNDO records 1/PAGE_SIZE of the actual modified byte range, undermining UNDO correctness.