diff options
Diffstat (limited to 'pkg/sentry/fsimpl/gofer/gofer.go')
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/gofer.go | 66 |
1 files changed, 39 insertions, 27 deletions
diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go index 2485cdb53..293df2545 100644 --- a/pkg/sentry/fsimpl/gofer/gofer.go +++ b/pkg/sentry/fsimpl/gofer/gofer.go @@ -452,6 +452,16 @@ type dentry struct { // fs is the owning filesystem. fs is immutable. fs *filesystem + // parent is this dentry's parent directory. Each dentry holds a reference + // on its parent. If this dentry is a filesystem root, parent is nil. + // parent is protected by filesystem.renameMu. + parent *dentry + + // name is the name of this dentry in its parent. If this dentry is a + // filesystem root, name is the empty string. name is protected by + // filesystem.renameMu. + name string + // We don't support hard links, so each dentry maps 1:1 to an inode. // file is the unopened p9.File that backs this dentry. file is immutable. @@ -469,10 +479,15 @@ type dentry struct { dirMu sync.Mutex - // If this dentry represents a directory, and InteropModeShared is not in - // effect, negativeChildren is a set of child names in this directory that - // are known not to exist. negativeChildren is protected by dirMu. - negativeChildren map[string]struct{} + // If this dentry represents a directory, children contains: + // + // - Mappings of child filenames to dentries representing those children. + // + // - Mappings of child filenames that are known not to exist to nil + // dentries (only if InteropModeShared is not in effect). + // + // children is protected by dirMu. + children map[string]*dentry // If this dentry represents a directory, InteropModeShared is not in // effect, and dirents is not nil, it is a cache of all entries in the @@ -910,9 +925,9 @@ func (d *dentry) checkCachingLocked() { // Dentry has already been destroyed. return } - // Non-child dentries with zero references are no longer reachable by path - // resolution and should be dropped immediately. - if d.vfsd.Parent() == nil || d.vfsd.IsDisowned() { + // Deleted and invalidated dentries with zero references are no longer + // reachable by path resolution and should be dropped immediately. + if d.vfsd.IsDead() { if d.cached { d.fs.cachedDentries.Remove(d) d.fs.cachedDentriesLen-- @@ -937,28 +952,26 @@ func (d *dentry) checkCachingLocked() { d.fs.cachedDentries.Remove(victim) d.fs.cachedDentriesLen-- victim.cached = false - // victim.refs may have become non-zero from an earlier path - // resolution since it was inserted into fs.cachedDentries; see - // dentry.incRefLocked(). Either way, we brought - // fs.cachedDentriesLen back down to fs.opts.maxCachedDentries, so - // we don't loop. + // victim.refs may have become non-zero from an earlier path resolution + // since it was inserted into fs.cachedDentries. if atomic.LoadInt64(&victim.refs) == 0 { - if victimParentVFSD := victim.vfsd.Parent(); victimParentVFSD != nil { - victimParent := victimParentVFSD.Impl().(*dentry) - victimParent.dirMu.Lock() - if !victim.vfsd.IsDisowned() { - // victim can't be a mount point (in any mount - // namespace), since VFS holds references on mount - // points. - d.fs.vfsfs.VirtualFilesystem().ForceDeleteDentry(&victim.vfsd) + if victim.parent != nil { + victim.parent.dirMu.Lock() + if !victim.vfsd.IsDead() { + // Note that victim can't be a mount point (in any mount + // namespace), since VFS holds references on mount points. + d.fs.vfsfs.VirtualFilesystem().InvalidateDentry(&victim.vfsd) + delete(victim.parent.children, victim.name) // We're only deleting the dentry, not the file it // represents, so we don't need to update // victimParent.dirents etc. } - victimParent.dirMu.Unlock() + victim.parent.dirMu.Unlock() } victim.destroyLocked() } + // Whether or not victim was destroyed, we brought fs.cachedDentriesLen + // back down to fs.opts.maxCachedDentries, so we don't loop. } } @@ -1005,12 +1018,11 @@ func (d *dentry) destroyLocked() { d.fs.syncMu.Lock() delete(d.fs.dentries, d) d.fs.syncMu.Unlock() - // Drop the reference held by d on its parent. - if parentVFSD := d.vfsd.Parent(); parentVFSD != nil { - parent := parentVFSD.Impl().(*dentry) - // This is parent.DecRef() without recursive locking of d.fs.renameMu. - if refs := atomic.AddInt64(&parent.refs, -1); refs == 0 { - parent.checkCachingLocked() + // Drop the reference held by d on its parent without recursively locking + // d.fs.renameMu. + if d.parent != nil { + if refs := atomic.AddInt64(&d.parent.refs, -1); refs == 0 { + d.parent.checkCachingLocked() } else if refs < 0 { panic("gofer.dentry.DecRef() called without holding a reference") } |