diff options
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/filesystem.go | 22 |
1 files changed, 14 insertions, 8 deletions
diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go index c1c9ec008..97ce80853 100644 --- a/pkg/sentry/fsimpl/gofer/filesystem.go +++ b/pkg/sentry/fsimpl/gofer/filesystem.go @@ -117,6 +117,17 @@ func appendDentry(ds *[]*dentry, d *dentry) *[]*dentry { return ds } +// Precondition: !parent.isSynthetic() && !child.isSynthetic(). +func appendNewChildDentry(ds **[]*dentry, parent *dentry, child *dentry) { + // The new child was added to parent and took a ref on the parent (hence + // parent can be removed from cache). A new child has 0 refs for now. So + // checkCachingLocked() should be called on both. Call it first on the parent + // as it may create space in the cache for child to be inserted - hence + // avoiding a cache eviction. + *ds = appendDentry(*ds, parent) + *ds = appendDentry(*ds, child) +} + // Preconditions: ds != nil. func putDentrySlice(ds *[]*dentry) { // Allow dentries to be GC'd. @@ -258,11 +269,7 @@ func (fs *filesystem) getChildLocked(ctx context.Context, parent *dentry, name s return nil, err } parent.cacheNewChildLocked(child, name) - // For now, child has 0 references, so our caller should call - // child.checkCachingLocked(). parent gained a ref so we should also call - // parent.checkCachingLocked() so it can be removed from the cache if needed. - *ds = appendDentry(*ds, child) - *ds = appendDentry(*ds, parent) + appendNewChildDentry(ds, parent, child) return child, nil } @@ -1114,7 +1121,6 @@ func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.Resolving } return nil, err } - *ds = appendDentry(*ds, child) // Incorporate the fid that was opened by lcreate. useRegularFileFD := child.fileType() == linux.S_IFREG && !d.fs.opts.regularFilesUseSpecialFileFD if useRegularFileFD { @@ -1138,7 +1144,7 @@ func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.Resolving } // Insert the dentry into the tree. d.cacheNewChildLocked(child, name) - *ds = appendDentry(*ds, d) + appendNewChildDentry(ds, d, child) if d.cachedMetadataAuthoritative() { d.touchCMtime() d.dirents = nil @@ -1333,9 +1339,9 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa // parent isn't actually changing. if oldParent != newParent { oldParent.decRefNoCaching() - ds = appendDentry(ds, oldParent) newParent.IncRef() ds = appendDentry(ds, newParent) + ds = appendDentry(ds, oldParent) if renamed.isSynthetic() { oldParent.syntheticChildren-- newParent.syntheticChildren++ |