don't create src dir on readonly bind mount (#3084)

core/startos/src/disk/mount/filesystem/bind.rs

@@ -8,6 +8,7 @@ use sha2::Sha256;
 use ts_rs::TS;
 
 use super::FileSystem;
+use crate::disk::mount::filesystem::MountType;
 use crate::prelude::*;
 use crate::util::io::create_file;
 
@@ -48,7 +49,7 @@ impl<Src: AsRef<Path> + Send + Sync> FileSystem for Bind<Src> {
     fn extra_args(&self) -> impl IntoIterator<Item = impl AsRef<std::ffi::OsStr>> {
         ["--bind"]
     }
-    async fn pre_mount(&self, mountpoint: &Path) -> Result<(), Error> {
+    async fn pre_mount(&self, mountpoint: &Path, mount_type: MountType) -> Result<(), Error> {
         let from_meta = tokio::fs::metadata(&self.src).await.ok();
         let to_meta = tokio::fs::metadata(&mountpoint).await.ok();
         if matches!(self.filetype, FileType::File)
@@ -58,7 +59,7 @@ impl<Src: AsRef<Path> + Send + Sync> FileSystem for Bind<Src> {
             if to_meta.as_ref().map_or(false, |m| m.is_dir()) {
                 tokio::fs::remove_dir(mountpoint).await?;
             }
-            if from_meta.is_none() {
+            if from_meta.is_none() && mount_type == MountType::ReadWrite {
                 create_file(self.src.as_ref()).await?.sync_all().await?;
             }
             if to_meta.is_none() {
@@ -68,7 +69,7 @@ impl<Src: AsRef<Path> + Send + Sync> FileSystem for Bind<Src> {
             if to_meta.as_ref().map_or(false, |m| m.is_file()) {
                 tokio::fs::remove_file(mountpoint).await?;
             }
-            if from_meta.is_none() {
+            if from_meta.is_none() && mount_type == MountType::ReadWrite {
                 tokio::fs::create_dir_all(self.src.as_ref()).await?;
             }
             if to_meta.is_none() {

core/startos/src/disk/mount/filesystem/ecryptfs.rs

@@ -49,7 +49,7 @@ impl<EncryptedDir: AsRef<Path> + Send + Sync, Key: AsRef<str> + Send + Sync> Fil
         mountpoint: P,
         mount_type: super::MountType,
     ) -> Result<(), Error> {
-        self.pre_mount(mountpoint.as_ref()).await?;
+        self.pre_mount(mountpoint.as_ref(), mount_type).await?;
         Command::new("mount")
             .args(
                 default_mount_command(self, mountpoint, mount_type)

core/startos/src/disk/mount/filesystem/idmapped.rs

@@ -14,6 +14,7 @@ use tokio::process::Command;
 use ts_rs::TS;
 
 use super::FileSystem;
+use crate::disk::mount::filesystem::MountType;
 use crate::prelude::*;
 use crate::util::{FromStrParser, Invoke};
 
@@ -110,8 +111,8 @@ impl<Fs: FileSystem> FileSystem for IdMapped<Fs> {
     async fn source(&self) -> Result<Option<impl AsRef<Path>>, Error> {
         self.filesystem.source().await
     }
-    async fn pre_mount(&self, mountpoint: &Path) -> Result<(), Error> {
+    async fn pre_mount(&self, mountpoint: &Path, mount_type: MountType) -> Result<(), Error> {
-        self.filesystem.pre_mount(mountpoint).await?;
+        self.filesystem.pre_mount(mountpoint, mount_type).await?;
         let info = tokio::fs::metadata(mountpoint).await?;
         for i in &self.idmap {
             let uid_in_range = i.from_id <= info.uid() && i.from_id + i.range > info.uid();

core/startos/src/disk/mount/filesystem/mod.rs

@@ -69,7 +69,7 @@ pub(self) async fn default_mount_impl(
     mountpoint: impl AsRef<Path> + Send,
     mount_type: MountType,
 ) -> Result<(), Error> {
-    fs.pre_mount(mountpoint.as_ref()).await?;
+    fs.pre_mount(mountpoint.as_ref(), mount_type).await?;
     Command::from(default_mount_command(fs, mountpoint, mount_type).await?)
         .capture(false)
         .invoke(ErrorKind::Filesystem)
@@ -91,7 +91,11 @@ pub trait FileSystem: Send + Sync {
     fn source(&self) -> impl Future<Output = Result<Option<impl AsRef<Path>>, Error>> + Send {
         async { Ok(None::<&Path>) }
     }
-    fn pre_mount(&self, mountpoint: &Path) -> impl Future<Output = Result<(), Error>> + Send {
+    fn pre_mount(
+        &self,
+        mountpoint: &Path,
+        #[allow(unused_variables)] mount_type: MountType,
+    ) -> impl Future<Output = Result<(), Error>> + Send {
         async move {
             tokio::fs::create_dir_all(mountpoint).await?;
             Ok(())

core/startos/src/disk/mount/filesystem/overlayfs.rs

@@ -6,7 +6,7 @@ use digest::generic_array::GenericArray;
 use digest::{Digest, OutputSizeUser};
 use sha2::Sha256;
 
-use crate::disk::mount::filesystem::{FileSystem, ReadWrite};
+use crate::disk::mount::filesystem::{FileSystem, MountType, ReadWrite};
 use crate::disk::mount::guard::{GenericMountGuard, MountGuard};
 use crate::prelude::*;
 use crate::util::io::TmpDir;
@@ -38,7 +38,7 @@ impl<P0: AsRef<Path> + Send + Sync, P1: AsRef<Path> + Send + Sync, P2: AsRef<Pat
             Box::new(lazy_format!("workdir={}", self.work.as_ref().display())),
         ]
     }
-    async fn pre_mount(&self, mountpoint: &Path) -> Result<(), Error> {
+    async fn pre_mount(&self, mountpoint: &Path, _: MountType) -> Result<(), Error> {
         tokio::fs::create_dir_all(self.upper.as_ref()).await?;
         tokio::fs::create_dir_all(self.work.as_ref()).await?;
         tokio::fs::create_dir_all(mountpoint).await?;