[PATCH pynfs 3/3] Add README-blocklayout

[Daejun Park via B4 Relay <devnull+daejun7.park.samsung.com@kernel.org>]

From: Daejun Park <daejun7.park@samsung.com>

Describe how the block layout tests are run against Linux nfsd: the
kernel options and export option that nfsd needs to hand out block
layouts, a setup that the tests have been run with, the testserver.py
command line, and how to leave out the tests that commit ranges no
layout covered when testing a server that shuts down on them.

Signed-off-by: Daejun Park <daejun7.park@samsung.com>
---
 nfs4.1/README-blocklayout | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/nfs4.1/README-blocklayout b/nfs4.1/README-blocklayout
new file mode 100644
index 0000000..48d3c1b
--- /dev/null
+++ b/nfs4.1/README-blocklayout
@@ -0,0 +1,41 @@
+Testing a block layout server
+=============================
+
+The "block" tests (server41tests/st_block.py) run testserver.py as the
+pNFS client of a server that hands out block layouts (RFC 5663). They
+only send NFS operations: none of them reads or writes the shared
+volume, so the host that runs them does not need access to it.
+
+They ask for LAYOUT4_BLOCK_VOLUME layouts. Linux nfsd hands those out
+for an XFS export with the "pnfs" option when it is built with
+CONFIG_NFSD_BLOCKLAYOUT. With CONFIG_NFSD_SCSILAYOUT it also hands out
+SCSI layouts (RFC 8154) if the device supports persistent
+reservations; the tests do not use those.
+
+One setup that the tests have been run with:
+
+  - nfsd built with CONFIG_NFSD_BLOCKLAYOUT=y, and XFS (mkfs.xfs
+    defaults, internal log) on a whole NVMe namespace, exported with
+    this line in /etc/exports:
+
+        /export  10.10.0.0/24(rw,sync,no_root_squash,pnfs)
+
+  - The namespace came over NVMe/TCP from nvmet on another host. As
+    the pynfs host never touches the volume, any block device that
+    XFS can be made on works for these tests; a shared device only
+    matters for clients that do I/O through the layout.
+
+  - A directory /export/pynfs on the server that the test user can
+    write to, and on the pynfs host:
+
+        ./testserver.py SERVER:/export/pynfs --secure --maketree block
+
+    --secure sends from a privileged port, which nfsd requires unless
+    the export has "insecure". --maketree creates the files that the
+    tests expect; it is needed the first time.
+
+BLOCK7 to BLOCK10 commit ranges that no layout covered. A server that
+does not refuse those may allocate blocks for them or, as XFS did,
+shut the filesystem down, which makes the tests after them fail. To
+leave them out, add "noBLOCK7 noBLOCK8 noBLOCK9 noBLOCK10" after
+"block".

-- 
2.43.0