Return parent inode when umount for inval dentry cache

umount returns the parent's inode information, so that it is convenient
to call fuse's invali entry interface later to clarify the corresponding
dentry cache

Signed-off-by: zyfjeff <[email protected]>

Author: zyfjeff

src/api/pseudo_fs.rs

@@ -235,6 +235,12 @@ impl PseudoFs {
         self.inodes.store(Arc::new(hashmap));
     }
 
+    pub fn get_parent_inode(&self, ino: u64) -> Option<u64> {
+        let _guard = self.lock.lock();
+        let inodes = self.inodes.load();
+        inodes.get(&ino).map(|o| o.parent)
+    }
+
     #[allow(dead_code)]
     pub fn evict_inode(&self, ino: u64) {
         let _guard = self.lock.lock();

src/api/vfs/mod.rs

@@ -395,15 +395,21 @@ impl Vfs {
     }
 
     /// Umount a backend file system at path
-    pub fn umount(&self, path: &str) -> VfsResult<()> {
+    pub fn umount(&self, path: &str) -> VfsResult<(u64, u64)> {
         // Serialize mount operations. Do not expect poisoned lock here.
         let _guard = self.lock.lock().unwrap();
         let inode = self
             .root
             .path_walk(path)
             .map_err(VfsError::PathWalk)?
             .ok_or_else(|| VfsError::NotFound(path.to_string()))?;
-
+        let parent = self
+            .root
+            .get_parent_inode(inode)
+            .ok_or(VfsError::NotFound(format!(
+                "{}'s parent inode does not exist",
+                inode
+            )))?;
         let mut mountpoints = self.mountpoints.load().deref().deref().clone();
         let fs_idx = mountpoints
             .get(&inode)
@@ -437,7 +443,7 @@ impl Vfs {
         }
         self.superblocks.store(Arc::new(superblocks));
 
-        Ok(())
+        Ok((inode, parent))
     }
 
     /// Get the mounted backend file system alongside the path if there's one.