Update funmap support

src/context/memory.rs

@@ -19,7 +19,7 @@ pub struct Grant {
     flags: EntryFlags,
     mapped: bool,
     //TODO: This is probably a very heavy way to keep track of fmap'd files, perhaps move to the context?
-    desc_opt: Option<FileDescriptor>,
+    pub desc_opt: Option<FileDescriptor>,
 }
 
 impl Grant {
@@ -133,6 +133,11 @@ impl Grant {
 
         flush_all.flush(&mut active_table);
 
+        if let Some(desc) = self.desc_opt.take() {
+            //TODO: This imposes a large cost on unmapping, but that cost cannot be avoided without modifying fmap and funmap
+            let _ = desc.close();
+        }
+
         self.mapped = false;
     }
 

src/scheme/user.rs

@@ -30,6 +30,7 @@ pub struct UserInner {
     context: Weak<RwLock<Context>>,
     todo: WaitQueue<Packet>,
     fmap: Mutex<BTreeMap<u64, (Weak<RwLock<Context>>, FileDescriptor, Map)>>,
+    funmap: Mutex<BTreeMap<usize, usize>>,
     done: WaitMap<u64, usize>
 }
 
@@ -45,6 +46,7 @@ impl UserInner {
             context: context,
             todo: WaitQueue::new(),
             fmap: Mutex::new(BTreeMap::new()),
+            funmap: Mutex::new(BTreeMap::new()),
             done: WaitMap::new()
         }
     }
@@ -192,7 +194,11 @@ impl UserInner {
                 if let Some((context_weak, desc, map)) = self.fmap.lock().remove(&packet.id) {
                     if let Ok(address) = Error::demux(packet.a) {
                         //TODO: Protect against sharing addresses that are not page aligned
-                        packet.a = Error::mux(UserInner::capture_inner(&context_weak, address, map.size, map.flags, Some(desc)));
+                        let res = UserInner::capture_inner(&context_weak, address, map.size, map.flags, Some(desc));
+                        if let Ok(new_address) = res {
+                            self.funmap.lock().insert(new_address, address);
+                        }
+                        packet.a = Error::mux(res);
                     } else {
                         let _ = desc.close();
                     }
@@ -358,6 +364,19 @@ impl Scheme for UserScheme {
         result
     }
 
+    fn funmap(&self, new_address: usize) -> Result<usize> {
+        let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
+        let address_opt = {
+            let mut funmap = inner.funmap.lock();
+            funmap.remove(&new_address)
+        };
+        if let Some(address) = address_opt {
+            inner.call(SYS_FUNMAP, address, 0, 0)
+        } else {
+            Err(Error::new(EINVAL))
+        }
+    }
+
     fn fpath(&self, file: usize, buf: &mut [u8]) -> Result<usize> {
         let inner = self.inner.upgrade().ok_or(Error::new(ENODEV))?;
         let address = inner.capture_mut(buf)?;

src/syscall/fs.rs

@@ -413,22 +413,47 @@ pub fn funmap(virtual_address: usize) -> Result<usize> {
     if virtual_address == 0 {
         Ok(0)
     } else {
-        let contexts = context::contexts();
-        let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
-        let context = context_lock.read();
+        let mut desc_opt = None;
 
-        let mut grants = context.grants.lock();
+        {
+            let contexts = context::contexts();
+            let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
+            let context = context_lock.read();
 
-        for i in 0 .. grants.len() {
-            let start = grants[i].start_address().get();
-            let end = start + grants[i].size();
-            if virtual_address >= start && virtual_address < end {
-                grants.remove(i).unmap();
+            let mut grants = context.grants.lock();
 
-                return Ok(0);
+            for i in 0 .. grants.len() {
+                let start = grants[i].start_address().get();
+                let end = start + grants[i].size();
+                if virtual_address >= start && virtual_address < end {
+                    let mut grant = grants.remove(i);
+                    if grant.desc_opt.is_some() {
+                        desc_opt = grant.desc_opt.take();
+                        grant.unmap();
+                        break;
+                    }
+                }
             }
         }
 
-        Err(Error::new(EFAULT))
+        if let Some(desc) = desc_opt {
+            let scheme_id = {
+                let description = desc.description.read();
+                description.scheme
+            };
+
+            let scheme = {
+                let schemes = scheme::schemes();
+                let scheme = schemes.get(scheme_id).ok_or(Error::new(EBADF))?;
+                scheme.clone()
+            };
+            let res = scheme.funmap(virtual_address);
+
+            let _ = desc.close();
+
+            res
+        } else {
+            Err(Error::new(EFAULT))
+        }
     }
 }