ksud: restore stock mount after overlay mount. close #233

userspace/ksud/Cargo.lock

@@ -800,6 +800,7 @@ dependencies = [
  "libc",
  "log",
  "nom",
+ "proc-mounts",
  "procfs",
  "regex",
  "retry",
@@ -986,6 +987,15 @@ version = "6.4.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9b7820b9daea5457c9f21c69448905d723fbd21136ccf521748f23fd49e723ee"
 
+[[package]]
+name = "partition-identity"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9fa925f9becb532d758b0014b472c576869910929cf4c3f8054b386f19ab9e21"
+dependencies = [
+ "thiserror",
+]
+
 [[package]]
 name = "password-hash"
 version = "0.4.2"
@@ -1072,6 +1082,15 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "proc-mounts"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0d652f8435d0ab70bf4f3590a6a851d59604831a458086541b95238cc51ffcf2"
+dependencies = [
+ "partition-identity",
+]
+
 [[package]]
 name = "procfs"
 version = "0.15.1"

userspace/ksud/Cargo.toml

@@ -31,6 +31,7 @@ rust-embed = { version = "6.4.2", features = [
     "debug-embed",
     "compression", # must clean build after updating binaries
 ] }
+proc-mounts = "0.3"
 
 [target.'cfg(any(target_os = "android", target_os = "linux"))'.dependencies]
 sys-mount = { git = "https://github.com/tiann/sys-mount" }

userspace/ksud/src/event.rs

@@ -18,6 +18,19 @@ fn mount_partition(partition: &str, lowerdir: &mut Vec<String>) -> Result<()> {
         warn!("partition: {partition} is a symlink");
         return Ok(());
     }
+
+    // handle stock mounts under /partition, we should restore the mount point after overlay
+    let stock_mount = mount::StockMount::new(&format!("/{partition}/"))
+        .with_context(|| format!("get stock mount of partition: {partition} failed"))?;
+    let result = stock_mount.umount();
+    if result.is_err() {
+        let remount_result = stock_mount.remount();
+        if remount_result.is_err() {
+            log::error!("remount stock mount of failed: {:?}", remount_result);
+        }
+        bail!("umount stock mount of failed: {:?}", result);
+    }
+
     // add /partition as the lowerest dir
     let lowest_dir = format!("/{partition}");
     lowerdir.push(lowest_dir.clone());
@@ -25,7 +38,18 @@ fn mount_partition(partition: &str, lowerdir: &mut Vec<String>) -> Result<()> {
     let lowerdir = lowerdir.join(":");
     info!("partition: {partition} lowerdir: {lowerdir}");
 
-    mount::mount_overlay(&lowerdir, &lowest_dir)
+    let result = mount::mount_overlay(&lowerdir, &lowest_dir);
+
+    if result.is_ok() && stock_mount.remount().is_err() {
+        // if mount overlay ok but stock remount failed, we should umount overlay
+        warn!("remount stock mount of failed, umount overlay {lowest_dir} now");
+        if mount::umount_dir(&lowest_dir).is_err() {
+            warn!("umount overlay {lowest_dir} failed");
+        }
+    }
+
+    result
+    
 }
 
 pub fn mount_systemlessly(module_dir: &str) -> Result<()> {

userspace/ksud/src/mount.rs

@@ -252,3 +252,73 @@ impl StockOverlay {
         }
     }
 }
+
+// some ROMs mount device(ext4,exfat) to /vendor, when we do overlay mount, it will overlay
+// the stock mounts, these mounts include bt_firmware, wifi_firmware, etc.
+// so we to remount these mounts when we do overlay mount.
+// this is a workaround, we should find a better way to do this.
+#[derive(Debug)]
+pub struct StockMount {
+    mnt: String,
+    mountlist: proc_mounts::MountList,
+}
+
+impl StockMount {
+    pub fn new(mnt: &str) -> Result<Self> {
+        let mountlist = proc_mounts::MountList::new()?;
+        Ok(Self {
+            mnt: mnt.to_string(),
+            mountlist,
+        })
+    }
+
+    fn get_target_mounts(&self) -> Vec<&proc_mounts::MountInfo> {
+        let mounts = self
+            .mountlist
+            .destination_starts_with(&std::path::Path::new(&self.mnt))
+            .filter(|m| m.fstype != "overlay");
+        mounts.collect()
+    }
+
+    pub fn umount(&self) -> Result<()> {
+        let mounts = self.get_target_mounts();
+        log::info!("stock mount for {} : {:?}", self.mnt, mounts);
+        for m in mounts {
+            let dst = m
+                .dest
+                .to_str()
+                .ok_or(anyhow::anyhow!("Failed to get dst"))?;
+            umount_dir(dst)?;
+            log::info!("umount: {:?}", m);
+        }
+        Ok(())
+    }
+
+    pub fn remount(&self) -> Result<()> {
+        let mounts = self.get_target_mounts();
+        for m in mounts {
+            let src = std::fs::canonicalize(&m.source)?;
+
+            let src = src.to_str().ok_or(anyhow::anyhow!("Failed to get src"))?;
+            let dst = m
+                .dest
+                .to_str()
+                .ok_or(anyhow::anyhow!("Failed to get dst"))?;
+
+            let fstype = m.fstype.as_str();
+            let options = m.options.join(",");
+
+            log::info!("mount: {:?}", m);
+            std::process::Command::new("mount")
+                .arg("-t")
+                .arg(fstype)
+                .arg("-o")
+                .arg(options)
+                .arg(src)
+                .arg(dst)
+                .status()
+                .with_context(|| format!("Failed to mount {:?}", m))?;
+        }
+        Ok(())
+    }
+}