file: close() outside destructor

Once file::~file() is called, virtual functions no longer dispatch to the
derived type (which has since been destroyed) but to the base type, which
is uninteresting.

Move the call to close() from the destructor to fdrop().

Signed-off-by: Avi Kivity <avi@cloudius-systems.com>

fs/vfs/kern_descrip.cc

@@ -216,14 +216,6 @@ int fdrop(struct file *fp)
     if (__sync_fetch_and_sub(&fp->f_count, 1) != 1)
         return 0;
 
-    delete fp;
-    return 1;
-}
-
-file::~file()
-{
-    auto fp = this;
-
     /* We are about to free this file structure, but we still do things with it
      * so set the refcount to INT_MIN, fhold/fdrop may get called again
      * and we don't want to reach this point more than once.
@@ -232,6 +224,14 @@ file::~file()
 
     fp->f_count = INT_MIN;
     fo_close(fp);
+    delete fp;
+    return 1;
+}
+
+file::~file()
+{
+    auto fp = this;
+
     poll_drain(fp);
     if (f_epolls) {
         for (auto ep : *f_epolls) {