File 0002-Use-fsdev-multidevs-remap-on-QEMU-4.2.patch of Package virtme

From 5e80c9310ca2280db20ff984046251da88c0095f Mon Sep 17 00:00:00 2001
From: Andy Lutomirski <luto@kernel.org>
Date: Sun, 19 Jul 2020 11:05:29 -0700
Subject: [PATCH 2/6] Use -fsdev multidevs=remap on QEMU 4.2+

Apparently having a virtfs export that spans multiple host
filesystems can cause problems in the guest.  QEMU 4.2+ will warn
about this and supports a workaround: multidevs=remap.  Probe for
new enough QEMU and pass multidevs=remap on 4.2+.

See #60.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 virtme/commands/run.py | 9 ++++++---
 virtme/qemu_helpers.py | 4 ++++
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/virtme/commands/run.py b/virtme/commands/run.py
index 5d9b96b..46cf312 100644
--- a/virtme/commands/run.py
+++ b/virtme/commands/run.py
@@ -236,13 +236,16 @@ def find_kernel_and_mods(arch, args) -> Kernel:
 
     return kernel
 
-def export_virtfs(qemu, arch, qemuargs, path, mount_tag, security_model='none', readonly=True) -> None:
+def export_virtfs(qemu: qemu_helpers.Qemu, arch: architectures.Arch,
+                  qemuargs: List[str], path: str,
+                  mount_tag: str, security_model='none', readonly=True) -> None:
     # NB: We can't use -virtfs for this, because it can't handle a mount_tag
     # that isn't a valid QEMU identifier.
     fsid = 'virtfs%d' % len(qemuargs)
-    qemuargs.extend(['-fsdev', 'local,id=%s,path=%s,security_model=%s%s' %
+    qemuargs.extend(['-fsdev', 'local,id=%s,path=%s,security_model=%s%s%s' %
                      (fsid, qemu.quote_optarg(path),
-                      security_model, ',readonly' if readonly else '')])
+                      security_model, ',readonly' if readonly else '',
+                      ',multidevs=remap' if qemu.has_multidevs else '')])
     qemuargs.extend(['-device', '%s,fsdev=%s,mount_tag=%s' % (arch.virtio_dev_type('9p'), fsid, qemu.quote_optarg(mount_tag))])
 
 def quote_karg(arg: str) -> str:
diff --git a/virtme/qemu_helpers.py b/virtme/qemu_helpers.py
index 8ddc3dd..6ba0c03 100644
--- a/virtme/qemu_helpers.py
+++ b/virtme/qemu_helpers.py
@@ -30,6 +30,10 @@ class Qemu(object):
             self.cannot_overmount_virtfs = (
                 re.search(r'version 1\.[012345]', self.version) is not None)
 
+            # QEMU 4.2+ supports -fsdev multidevs=remap
+            self.has_multidevs = (
+                re.search(r'version (?:1\.|2\.|3\.|4\.[01][^\d])', self.version) is None)
+
     def quote_optarg(self, a):
         """Quote an argument to an option."""
         return a.replace(',', ',,')
-- 
2.27.0