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docs/pre11-batch-e.md

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+# Pre11 Batch E: Mount Device Argument Cleanup
+
+## Scope
+
+This batch consolidates caller-owned `device.N` argument cleanup in
+`erofs_mount()` and removes two impossible allocation checks. It does not
+change mount option semantics, GEOM ownership, device slot validation, mount
+error text, or any filesystem behavior.
+
+Modified files:
+
+- `src/super.c`
+- `docs/pre11-batch-e.md`
+
+## Changes
+
+After `erofs_parse_device_options()` succeeds, every exit from
+`erofs_mount()` now reaches one `out_args` label. Parse failure still returns
+directly because no caller-owned argument array has been transferred.
+
+The operation order remains:
+
+1. `erofs_parse_device_options()`
+2. `vfs_filteropt()`
+3. `vfs_getopt()`
+4. `erofs_open_device()`
+5. `erofs_update_iosize_max()`
+6. `erofs_mountfs()`
+7. `erofs_free_device_args()`
+8. `vfs_mountedfrom()`
+9. `erofs_statfs()`
+
+`out_args` only frees copied device arguments. It does not inspect or release
+`primary`. The existing `erofs_mountfs()` ownership transfer and all GEOM
+cleanup paths remain unchanged.
+
+The checks for `NULL` immediately following allocation of `packed_inode` and
+`metabox_en` were removed. Both allocations retain `M_WAITOK | M_ZERO`, so a
+successful return cannot produce `NULL`. No other allocation checks or flags
+were changed.
+
+## Ownership Paths
+
+| Path | Copied arguments | Primary device | Result |
+| --- | --- | --- | --- |
+| Parse failure | No caller ownership | Not opened | Return parser error directly |
+| Option filter failure | Freed at `out_args` | Not opened | Return `EINVAL` |
+| Invalid or missing `from` | Freed at `out_args` | Not opened | Return `EINVAL` |
+| Primary open failure | Freed at `out_args` | Open helper retains its existing cleanup contract | Return open error |
+| Mount setup failure | Freed at `out_args` | Ownership already transferred at `erofs_mountfs()` entry | Return mount error |
+| Success | Freed at `out_args` | Owned by the mounted filesystem | Publish mounted-from and run `statfs()` |
+
+## Static Verification
+
+- `erofs_free_device_args()` has one caller after the change.
+- `erofs_mountfs()` and `erofs_sb_free()` are unchanged.
+- The relative order of option filtering, option access, primary open, I/O
+  sizing, mount setup, argument cleanup, mounted-from publication, and statfs
+  is unchanged.
+- Existing errno values and mount error strings are unchanged.
+- Duplicate and missing external-device slot behavior is unchanged.
+- `git diff --check` passes.
+- The diff is restricted to the two declared Batch E files.
+
+## Validation Status
+
+No build, QEMU smoke test, or feature test was run for this batch. Runtime
+validation is deferred to the final Pre11 build and targeted smoke test.