diff options
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/filesystem.go | 17 | ||||
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/gofer.go | 11 |
2 files changed, 20 insertions, 8 deletions
diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go index cd5f5049e..491495b16 100644 --- a/pkg/sentry/fsimpl/gofer/filesystem.go +++ b/pkg/sentry/fsimpl/gofer/filesystem.go @@ -150,11 +150,9 @@ afterSymlink: return nil, err } if d != d.parent && !d.cachedMetadataAuthoritative() { - _, attrMask, attr, err := d.parent.file.getAttr(ctx, dentryAttrMask()) - if err != nil { + if err := d.parent.updateFromGetattr(ctx); err != nil { return nil, err } - d.parent.updateFromP9Attrs(attrMask, &attr) } rp.Advance() return d.parent, nil @@ -209,17 +207,28 @@ func (fs *filesystem) getChildLocked(ctx context.Context, vfsObj *vfs.VirtualFil // Preconditions: As for getChildLocked. !parent.isSynthetic(). func (fs *filesystem) revalidateChildLocked(ctx context.Context, vfsObj *vfs.VirtualFilesystem, parent *dentry, name string, child *dentry, ds **[]*dentry) (*dentry, error) { + if child != nil { + // Need to lock child.metadataMu because we might be updating child + // metadata. We need to hold the lock *before* getting metadata from the + // server and release it after updating local metadata. + child.metadataMu.Lock() + } qid, file, attrMask, attr, err := parent.file.walkGetAttrOne(ctx, name) if err != nil && err != syserror.ENOENT { + if child != nil { + child.metadataMu.Unlock() + } return nil, err } if child != nil { if !file.isNil() && inoFromPath(qid.Path) == child.ino { // The file at this path hasn't changed. Just update cached metadata. file.close(ctx) - child.updateFromP9Attrs(attrMask, &attr) + child.updateFromP9AttrsLocked(attrMask, &attr) + child.metadataMu.Unlock() return child, nil } + child.metadataMu.Unlock() if file.isNil() && child.isSynthetic() { // We have a synthetic file, and no remote file has arisen to // replace it. diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go index b74d489a0..ba7f650b3 100644 --- a/pkg/sentry/fsimpl/gofer/gofer.go +++ b/pkg/sentry/fsimpl/gofer/gofer.go @@ -785,8 +785,8 @@ func (d *dentry) cachedMetadataAuthoritative() bool { // updateFromP9Attrs is called to update d's metadata after an update from the // remote filesystem. -func (d *dentry) updateFromP9Attrs(mask p9.AttrMask, attr *p9.Attr) { - d.metadataMu.Lock() +// Precondition: d.metadataMu must be locked. +func (d *dentry) updateFromP9AttrsLocked(mask p9.AttrMask, attr *p9.Attr) { if mask.Mode { if got, want := uint32(attr.Mode.FileType()), d.fileType(); got != want { d.metadataMu.Unlock() @@ -822,7 +822,6 @@ func (d *dentry) updateFromP9Attrs(mask p9.AttrMask, attr *p9.Attr) { if mask.Size { d.updateFileSizeLocked(attr.Size) } - d.metadataMu.Unlock() } // Preconditions: !d.isSynthetic() @@ -834,6 +833,10 @@ func (d *dentry) updateFromGetattr(ctx context.Context) error { file p9file handleMuRLocked bool ) + // d.metadataMu must be locked *before* we getAttr so that we do not end up + // updating stale attributes in d.updateFromP9AttrsLocked(). + d.metadataMu.Lock() + defer d.metadataMu.Unlock() d.handleMu.RLock() if !d.handle.file.isNil() { file = d.handle.file @@ -849,7 +852,7 @@ func (d *dentry) updateFromGetattr(ctx context.Context) error { if err != nil { return err } - d.updateFromP9Attrs(attrMask, &attr) + d.updateFromP9AttrsLocked(attrMask, &attr) return nil } |