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-rw-r--r--pkg/sentry/fsimpl/tmpfs/tmpfs.go34
1 files changed, 34 insertions, 0 deletions
diff --git a/pkg/sentry/fsimpl/tmpfs/tmpfs.go b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
index e1439dddb..e2a0aac69 100644
--- a/pkg/sentry/fsimpl/tmpfs/tmpfs.go
+++ b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
@@ -74,6 +74,8 @@ type filesystem struct {
mu sync.RWMutex `state:"nosave"`
nextInoMinusOne uint64 // accessed using atomic memory operations
+
+ root *dentry
}
// Name implements vfs.FilesystemType.Name.
@@ -197,6 +199,7 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
fs.vfsfs.DecRef(ctx)
return nil, nil, fmt.Errorf("invalid tmpfs root file type: %#o", rootFileType)
}
+ fs.root = root
return &fs.vfsfs, &root.vfsd, nil
}
@@ -208,6 +211,37 @@ func NewFilesystem(ctx context.Context, vfsObj *vfs.VirtualFilesystem, creds *au
// Release implements vfs.FilesystemImpl.Release.
func (fs *filesystem) Release(ctx context.Context) {
fs.vfsfs.VirtualFilesystem().PutAnonBlockDevMinor(fs.devMinor)
+ fs.mu.Lock()
+ if fs.root.inode.isDir() {
+ fs.root.releaseChildrenLocked(ctx)
+ }
+ fs.mu.Unlock()
+}
+
+// releaseChildrenLocked is called on the mount point by filesystem.Release() to
+// destroy all objects in the mount. It performs a depth-first walk of the
+// filesystem and "unlinks" everything by decrementing link counts
+// appropriately. There should be no open file descriptors when this is called,
+// so each inode should only have one outstanding reference that is removed once
+// its link count hits zero.
+//
+// Note that we do not update filesystem state precisely while tearing down (for
+// instance, the child maps are ignored)--we only care to remove all remaining
+// references so that every filesystem object gets destroyed. Also note that we
+// do not need to trigger DecRef on the mount point itself or any child mount;
+// these are taken care of by the destructor of the enclosing MountNamespace.
+//
+// Precondition: filesystem.mu is held.
+func (d *dentry) releaseChildrenLocked(ctx context.Context) {
+ dir := d.inode.impl.(*directory)
+ for _, child := range dir.childMap {
+ if child.inode.isDir() {
+ child.releaseChildrenLocked(ctx)
+ child.inode.decLinksLocked(ctx) // link for child/.
+ dir.inode.decLinksLocked(ctx) // link for child/..
+ }
+ child.inode.decLinksLocked(ctx) // link for child
+ }
}
// immutable