[PATCH 2/2] img/app: move virtio-fs mountpoint to /host

[Alyssa Ross <hi@alyssa.is>]

It doesn't really make sense for this to be under /run, and
"virtiofs0" is not a very descriptive name, especially now that it's
no longer used on the host side.

Signed-off-by: Alyssa Ross <hi@alyssa.is>
---
 Documentation/using-spectrum/vm-file-access.adoc |  8 ++++----
 .../image/etc/vm-sysupdate.d/50-verity.transfer  |  2 +-
 .../image/etc/vm-sysupdate.d/60-root.transfer    |  2 +-
 .../image/etc/vm-sysupdate.d/70-kernel.transfer  |  2 +-
 img/app/Makefile                                 |  2 +-
 .../image/etc/flatpak/installations.d/extra.conf |  2 +-
 img/app/image/etc/mdev/virtiofs                  |  8 ++------
 img/app/image/etc/s6-rc/app/run                  | 16 ++++++++--------
 tools/default.nix                                |  2 +-
 vm/app/systemd-sysupdate/download-update         |  6 +++---
 10 files changed, 23 insertions(+), 27 deletions(-)

diff --git a/Documentation/using-spectrum/vm-file-access.adoc b/Documentation/using-spectrum/vm-file-access.adoc
index 1b4fe9a5..a76272f1 100644
--- a/Documentation/using-spectrum/vm-file-access.adoc
+++ b/Documentation/using-spectrum/vm-file-access.adoc
@@ -37,10 +37,10 @@ the portal.
 When using an application that doesn't implement the File Chooser API,
 you can still give it access to files manually.  Each VM has
 xref:creating-custom-vms.adoc#filesystem[access] to the
-/run/vm/by-id/_VM ID_/fs directory on the host (mounted at
-/run/virtiofs/virtiofs0 in the default Spectrum VM image).  For the
-VM, this directory is read-only, but writeable files and directories
-can be bind-mounted into it:
+/run/vm/by-id/_VM ID_/fs directory on the host (mounted at /host in
+the default Spectrum VM image).  For the VM, this directory is
+read-only, but writeable files and directories can be bind-mounted
+into it:
 
 [example]
 ====
diff --git a/host/rootfs/image/etc/vm-sysupdate.d/50-verity.transfer b/host/rootfs/image/etc/vm-sysupdate.d/50-verity.transfer
index ab4997c8..8c764fbd 100644
--- a/host/rootfs/image/etc/vm-sysupdate.d/50-verity.transfer
+++ b/host/rootfs/image/etc/vm-sysupdate.d/50-verity.transfer
@@ -13,6 +13,6 @@ MatchPattern=Spectrum_@v_@u.verity
 
 [Target]
 Type=regular-file
-Path=/run/virtiofs/virtiofs0/updates
+Path=/host/updates
 MatchPattern=Spectrum_@v_@u.verity
 Mode=0644
diff --git a/host/rootfs/image/etc/vm-sysupdate.d/60-root.transfer b/host/rootfs/image/etc/vm-sysupdate.d/60-root.transfer
index 8a317568..93af34ac 100644
--- a/host/rootfs/image/etc/vm-sysupdate.d/60-root.transfer
+++ b/host/rootfs/image/etc/vm-sysupdate.d/60-root.transfer
@@ -13,6 +13,6 @@ MatchPattern=Spectrum_@v_@u.root
 
 [Target]
 Type=regular-file
-Path=/run/virtiofs/virtiofs0/updates
+Path=/host/updates
 MatchPattern=Spectrum_@v_@u.root
 Mode=0644
diff --git a/host/rootfs/image/etc/vm-sysupdate.d/70-kernel.transfer b/host/rootfs/image/etc/vm-sysupdate.d/70-kernel.transfer
index cb181239..90d26874 100644
--- a/host/rootfs/image/etc/vm-sysupdate.d/70-kernel.transfer
+++ b/host/rootfs/image/etc/vm-sysupdate.d/70-kernel.transfer
@@ -13,6 +13,6 @@ MatchPattern=Spectrum_@v.efi
 
 [Target]
 Type=regular-file
-Path=/run/virtiofs/virtiofs0/updates
+Path=/host/updates
 MatchPattern=Spectrum_@v.efi
 Mode=0644
diff --git a/img/app/Makefile b/img/app/Makefile
index 69c85bba..7e3d05b2 100644
--- a/img/app/Makefile
+++ b/img/app/Makefile
@@ -30,7 +30,7 @@ $(imgdir)/appvm/blk/root.img: ../../scripts/make-gpt.sh ../../scripts/sfdisk-fie
 	    build/rootfs.erofs:root:5460386f-2203-4911-8694-91400125c604:root
 	mv $@.tmp $@
 
-DIRS = dev home/user run mnt proc sys tmp \
+DIRS = dev home/user host run mnt proc sys tmp \
 	etc/s6-linux-init/run-image/pipewire \
 	etc/s6-linux-init/run-image/service \
 	etc/s6-linux-init/run-image/user \
diff --git a/img/app/image/etc/flatpak/installations.d/extra.conf b/img/app/image/etc/flatpak/installations.d/extra.conf
index 448902b4..4b3bd5e6 100644
--- a/img/app/image/etc/flatpak/installations.d/extra.conf
+++ b/img/app/image/etc/flatpak/installations.d/extra.conf
@@ -2,4 +2,4 @@
 # SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is>
 
 [Installation "virtiofs"]
-Path=/run/virtiofs/virtiofs0/config/flatpak
+Path=/host/config/flatpak
diff --git a/img/app/image/etc/mdev/virtiofs b/img/app/image/etc/mdev/virtiofs
index bda77483..a0b9dd7d 100755
--- a/img/app/image/etc/mdev/virtiofs
+++ b/img/app/image/etc/mdev/virtiofs
@@ -3,10 +3,6 @@
 # SPDX-FileCopyrightText: 2022-2023 Alyssa Ross <hi@alyssa.is>
 
 background {
-  # There's currently no kernel mechanism to let us enumerate available
-  # virtiofs filesystems, so we only supported a single, hardcoded
-  # filesystem tag for now.
-  if { mkdir -p /run/virtiofs/virtiofs0 }
-  if { mount -t virtiofs -o nodev host /run/virtiofs/virtiofs0 }
-  /etc/mdev/listen virtiofs0
+  if { mount -t virtiofs -o nodev host /host }
+  /etc/mdev/listen virtiofs-host
 }
diff --git a/img/app/image/etc/s6-rc/app/run b/img/app/image/etc/s6-rc/app/run
index 997897de..f91877d4 100755
--- a/img/app/image/etc/s6-rc/app/run
+++ b/img/app/image/etc/s6-rc/app/run
@@ -7,27 +7,27 @@ export TMPDIR /run
 export HOME /home/user
 cd /home/user
 
-if { /etc/mdev/wait virtiofs0 }
+if { /etc/mdev/wait virtiofs-host }
 
 foreground {
-  redirfd -r 0 /run/virtiofs/virtiofs0/config/type
+  redirfd -r 0 /host/config/type
   withstdinas -E type
   case $type {
     appimage {
       if { modprobe loop }
       if {
-        backtick -E offset { /run/virtiofs/virtiofs0/config/run --appimage-offset }
-        mount -o offset=${offset},nodev /run/virtiofs/virtiofs0/config/run /mnt
+        backtick -E offset { /host/config/run --appimage-offset }
+        mount -o offset=${offset},nodev /host/config/run /mnt
       }
       s6-setuidgid user
-      export APPIMAGE /run/virtiofs/virtiofs0/config/run
+      export APPIMAGE /host/config/run
       export APPDIR /mnt
       export ARGV0 /mnt/AppRun
       export LD_LIBRARY_PATH /lib64
       /mnt/AppRun
     }
     flatpak {
-      s6-envdir -fnL /run/virtiofs/virtiofs0/config/params
+      s6-envdir -fnL /host/config/params
       s6-setuidgid user
       multisubstitute {
         importas -iu id id
@@ -42,12 +42,12 @@ foreground {
     nix {
       if {
 	mount -t overlay
-	  -o ro,nosuid,nodev,lowerdir=/nix/store:/run/virtiofs/virtiofs0/config/nix/store
+	  -o ro,nosuid,nodev,lowerdir=/nix/store:/host/config/nix/store
 	  store /nix/store
       }
 
       s6-setuidgid user
-      /run/virtiofs/virtiofs0/config/run
+      /host/config/run
     }
   }
   fdmove -c 1 2
diff --git a/tools/default.nix b/tools/default.nix
index da82f075..56f41cd9 100644
--- a/tools/default.nix
+++ b/tools/default.nix
@@ -101,7 +101,7 @@ stdenv.mkDerivation (finalAttrs: {
     (lib.mesonBool "app" appSupport)
     (lib.mesonBool "host" hostSupport)
     (lib.mesonBool "driver" driverSupport)
-    "-Dhostfsrootdir=/run/virtiofs/virtiofs0"
+    "-Dhostfsrootdir=/host"
     "-Dtests=false"
     "-Dunwind=false"
     "-Dwerror=true"
diff --git a/vm/app/systemd-sysupdate/download-update b/vm/app/systemd-sysupdate/download-update
index 40fde88d..b76c9deb 100755
--- a/vm/app/systemd-sysupdate/download-update
+++ b/vm/app/systemd-sysupdate/download-update
@@ -5,7 +5,7 @@
 export LC_ALL C
 export LANGUAGE C
 unshare -mr
-if { mount -toverlay -o nosuid,nodev,noexec,nosymfollow,lowerdir=/run/virtiofs/virtiofs0/etc:/etc -- overlay /etc }
+if { mount -toverlay -o nosuid,nodev,noexec,nosymfollow,lowerdir=/host/etc:/etc -- overlay /etc }
 backtick tmpdir { mktemp -d /tmp/sysupdate-XXXXXX }
 # Not a useless use of cat: if there are NUL bytes in the URL
 # busybox's awk might misbehave.
@@ -70,6 +70,6 @@ if {
 # they cause globbing in the curl command-line tool by default.  Use --globoff
 # to disable this feature.
 if { $CURL_PATH -L --proto-redir =http,https --globoff
-     -o /run/virtiofs/virtiofs0/updates/SHA256SUMS -- ${update_url}/SHA256SUMS }
+     -o /host/updates/SHA256SUMS -- ${update_url}/SHA256SUMS }
 $CURL_PATH -L --proto-redir =http,https --globoff
-     -o /run/virtiofs/virtiofs0/updates/SHA256SUMS.sha256.asc -- ${update_url}/SHA256SUMS.sha256.asc
+     -o /host/updates/SHA256SUMS.sha256.asc -- ${update_url}/SHA256SUMS.sha256.asc
-- 
2.51.0