From d71e19fdb7824530f8af7a41dfc134ddd5c2550e Mon Sep 17 00:00:00 2001
From: Dongsheng Yang <dongsheng.yang@linux.dev>
Date: Tue, 12 Aug 2025 16:24:17 +0800
Subject: [PATCH 1/2] Fill in mail and code for pcache v5

---
 pcache/pcache_index.md |  1 +
 pcache/pcache_v5.md    | 51 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)
 create mode 100644 pcache/pcache_v5.md

diff --git a/pcache/pcache_index.md b/pcache/pcache_index.md
index 5da3ffe..2132302 100644
--- a/pcache/pcache_index.md
+++ b/pcache/pcache_index.md
@@ -7,3 +7,4 @@ layout: default
 - [PCache RFC](pcache_RFC.md)
 - [PCache RFC V2](pcache_RFC_V2.md)
 - [PCache v4](pcache_v4.md)
+- [PCache v5](pcache_v5.md)
diff --git a/pcache/pcache_v5.md b/pcache/pcache_v5.md
new file mode 100644
index 0000000..35ce1b6
--- /dev/null
+++ b/pcache/pcache_v5.md
@@ -0,0 +1,51 @@
+# PCache v5
+
+This document summarizes **dm-pcache** patch set v5.  It is based on v6.16 of
+the Linux kernel and contains the latest updates and testing results for the
+persistent cache target.
+
+## Mail
+> Hi Mikulas,
+> This is V5 for dm-pcache, please consider merging.
+>
+> As you requested, I've squashed these patches into a single patch based on
+> v6.16. If anything needs tweaking while merging, feel free to modify it
+> directly. I can also send a rebased version on top of the linux-dm branch if
+> you prefer.
+>
+> This patch has been tested extensively. Once it's merged into linux-dm I'll
+> keep running ongoing tests against dm-6.18.
+
+## Code
+https://github.com/DataTravelGuide/linux/tree/pcache_v5
+
+## Changelog
+
+### V5 from V4
+- Fix `get_n_vecs()` bug when the buffer is not page‑aligned; use
+  `bio_add_max_vecs()` instead.
+- Use `kvcalloc()` for allocations larger than 32,768 bytes.
+- For mempool allocations, try `GFP_NOWAIT` first and fall back to
+  `GFP_NOIO`.
+
+## Testing
+The following tests were executed against dm-pcache v5:
+
+1. **dtg-tests for pcache** – includes dmsetup operations, failslab,
+   fault injection (`fail_make_request`) and backing device delay tests,
+   plus xfstests (`generic/rw`) under various parameters.
+2. **Striped pmem as cache device** – dtg-tests suite executed with a
+   striped pmem configuration.
+3. **KASAN and memleak modes** – all of the above tests run with KASAN
+   and memory leak detection enabled.
+4. **gcov coverage** – reported 100% function coverage and 90%+ line
+   coverage; remaining uncovered code includes `BUG()` lines and
+   difficult‑to‑reach error paths.  The `mempool_alloc` path with
+   `GFP_NOIO` was exercised.
+
+## Results
+- [dtg-tests (virtio)](https://datatravelguide.github.io/dtg-blog/pcache/pcache_v5_result_virtio/results.html)
+- [dtg-tests (striped pmem)](https://datatravelguide.github.io/dtg-blog/pcache/pcache_v5_result_ram/results.html)
+- [KASAN & memleak tests](https://datatravelguide.github.io/dtg-blog/pcache/pcache_v5_result_kasan/results.html)
+- [Coverage report](https://datatravelguide.github.io/dtg-blog/pcache/pcache_cov_v5/dm-pcache/index.html)
+

From b5e7e320ae4856ef26e0c15e8772311d4c866902 Mon Sep 17 00:00:00 2001
From: Dongsheng Yang <dongsheng.yang@linux.dev>
Date: Tue, 12 Aug 2025 16:34:16 +0800
Subject: [PATCH 2/2] link pcache v5 cover letter

---
 pcache/pcache_v5.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/pcache/pcache_v5.md b/pcache/pcache_v5.md
index 35ce1b6..d586d34 100644
--- a/pcache/pcache_v5.md
+++ b/pcache/pcache_v5.md
@@ -16,6 +16,8 @@ persistent cache target.
 > This patch has been tested extensively. Once it's merged into linux-dm I'll
 > keep running ongoing tests against dm-6.18.
 
+[Full cover letter on dm-devel](https://marc.info/?l=dm-devel&m=175498716132537)
+
 ## Code
 https://github.com/DataTravelGuide/linux/tree/pcache_v5