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-rw-r--r--pkg/sentry/fsimpl/verity/dentry_list.go221
-rw-r--r--pkg/sentry/fsimpl/verity/filesystem.go47
-rw-r--r--pkg/sentry/fsimpl/verity/verity.go261
-rw-r--r--pkg/sentry/fsimpl/verity/verity_state_autogen.go76
4 files changed, 532 insertions, 73 deletions
diff --git a/pkg/sentry/fsimpl/verity/dentry_list.go b/pkg/sentry/fsimpl/verity/dentry_list.go
new file mode 100644
index 000000000..ace6086b7
--- /dev/null
+++ b/pkg/sentry/fsimpl/verity/dentry_list.go
@@ -0,0 +1,221 @@
+package verity
+
+// ElementMapper provides an identity mapping by default.
+//
+// This can be replaced to provide a struct that maps elements to linker
+// objects, if they are not the same. An ElementMapper is not typically
+// required if: Linker is left as is, Element is left as is, or Linker and
+// Element are the same type.
+type dentryElementMapper struct{}
+
+// linkerFor maps an Element to a Linker.
+//
+// This default implementation should be inlined.
+//
+//go:nosplit
+func (dentryElementMapper) linkerFor(elem *dentry) *dentry { return elem }
+
+// List is an intrusive list. Entries can be added to or removed from the list
+// in O(1) time and with no additional memory allocations.
+//
+// The zero value for List is an empty list ready to use.
+//
+// To iterate over a list (where l is a List):
+// for e := l.Front(); e != nil; e = e.Next() {
+// // do something with e.
+// }
+//
+// +stateify savable
+type dentryList struct {
+ head *dentry
+ tail *dentry
+}
+
+// Reset resets list l to the empty state.
+func (l *dentryList) Reset() {
+ l.head = nil
+ l.tail = nil
+}
+
+// Empty returns true iff the list is empty.
+//
+//go:nosplit
+func (l *dentryList) Empty() bool {
+ return l.head == nil
+}
+
+// Front returns the first element of list l or nil.
+//
+//go:nosplit
+func (l *dentryList) Front() *dentry {
+ return l.head
+}
+
+// Back returns the last element of list l or nil.
+//
+//go:nosplit
+func (l *dentryList) Back() *dentry {
+ return l.tail
+}
+
+// Len returns the number of elements in the list.
+//
+// NOTE: This is an O(n) operation.
+//
+//go:nosplit
+func (l *dentryList) Len() (count int) {
+ for e := l.Front(); e != nil; e = (dentryElementMapper{}.linkerFor(e)).Next() {
+ count++
+ }
+ return count
+}
+
+// PushFront inserts the element e at the front of list l.
+//
+//go:nosplit
+func (l *dentryList) PushFront(e *dentry) {
+ linker := dentryElementMapper{}.linkerFor(e)
+ linker.SetNext(l.head)
+ linker.SetPrev(nil)
+ if l.head != nil {
+ dentryElementMapper{}.linkerFor(l.head).SetPrev(e)
+ } else {
+ l.tail = e
+ }
+
+ l.head = e
+}
+
+// PushBack inserts the element e at the back of list l.
+//
+//go:nosplit
+func (l *dentryList) PushBack(e *dentry) {
+ linker := dentryElementMapper{}.linkerFor(e)
+ linker.SetNext(nil)
+ linker.SetPrev(l.tail)
+ if l.tail != nil {
+ dentryElementMapper{}.linkerFor(l.tail).SetNext(e)
+ } else {
+ l.head = e
+ }
+
+ l.tail = e
+}
+
+// PushBackList inserts list m at the end of list l, emptying m.
+//
+//go:nosplit
+func (l *dentryList) PushBackList(m *dentryList) {
+ if l.head == nil {
+ l.head = m.head
+ l.tail = m.tail
+ } else if m.head != nil {
+ dentryElementMapper{}.linkerFor(l.tail).SetNext(m.head)
+ dentryElementMapper{}.linkerFor(m.head).SetPrev(l.tail)
+
+ l.tail = m.tail
+ }
+ m.head = nil
+ m.tail = nil
+}
+
+// InsertAfter inserts e after b.
+//
+//go:nosplit
+func (l *dentryList) InsertAfter(b, e *dentry) {
+ bLinker := dentryElementMapper{}.linkerFor(b)
+ eLinker := dentryElementMapper{}.linkerFor(e)
+
+ a := bLinker.Next()
+
+ eLinker.SetNext(a)
+ eLinker.SetPrev(b)
+ bLinker.SetNext(e)
+
+ if a != nil {
+ dentryElementMapper{}.linkerFor(a).SetPrev(e)
+ } else {
+ l.tail = e
+ }
+}
+
+// InsertBefore inserts e before a.
+//
+//go:nosplit
+func (l *dentryList) InsertBefore(a, e *dentry) {
+ aLinker := dentryElementMapper{}.linkerFor(a)
+ eLinker := dentryElementMapper{}.linkerFor(e)
+
+ b := aLinker.Prev()
+ eLinker.SetNext(a)
+ eLinker.SetPrev(b)
+ aLinker.SetPrev(e)
+
+ if b != nil {
+ dentryElementMapper{}.linkerFor(b).SetNext(e)
+ } else {
+ l.head = e
+ }
+}
+
+// Remove removes e from l.
+//
+//go:nosplit
+func (l *dentryList) Remove(e *dentry) {
+ linker := dentryElementMapper{}.linkerFor(e)
+ prev := linker.Prev()
+ next := linker.Next()
+
+ if prev != nil {
+ dentryElementMapper{}.linkerFor(prev).SetNext(next)
+ } else if l.head == e {
+ l.head = next
+ }
+
+ if next != nil {
+ dentryElementMapper{}.linkerFor(next).SetPrev(prev)
+ } else if l.tail == e {
+ l.tail = prev
+ }
+
+ linker.SetNext(nil)
+ linker.SetPrev(nil)
+}
+
+// Entry is a default implementation of Linker. Users can add anonymous fields
+// of this type to their structs to make them automatically implement the
+// methods needed by List.
+//
+// +stateify savable
+type dentryEntry struct {
+ next *dentry
+ prev *dentry
+}
+
+// Next returns the entry that follows e in the list.
+//
+//go:nosplit
+func (e *dentryEntry) Next() *dentry {
+ return e.next
+}
+
+// Prev returns the entry that precedes e in the list.
+//
+//go:nosplit
+func (e *dentryEntry) Prev() *dentry {
+ return e.prev
+}
+
+// SetNext assigns 'entry' as the entry that follows e in the list.
+//
+//go:nosplit
+func (e *dentryEntry) SetNext(elem *dentry) {
+ e.next = elem
+}
+
+// SetPrev assigns 'entry' as the entry that precedes e in the list.
+//
+//go:nosplit
+func (e *dentryEntry) SetPrev(elem *dentry) {
+ e.prev = elem
+}
diff --git a/pkg/sentry/fsimpl/verity/filesystem.go b/pkg/sentry/fsimpl/verity/filesystem.go
index e147d6b07..52d47994d 100644
--- a/pkg/sentry/fsimpl/verity/filesystem.go
+++ b/pkg/sentry/fsimpl/verity/filesystem.go
@@ -66,40 +66,23 @@ func putDentrySlice(ds *[]*dentry) {
dentrySlicePool.Put(ds)
}
-// renameMuRUnlockAndCheckDrop calls fs.renameMu.RUnlock(), then calls
-// dentry.checkDropLocked on all dentries in *ds with fs.renameMu locked for
+// renameMuRUnlockAndCheckCaching calls fs.renameMu.RUnlock(), then calls
+// dentry.checkCachingLocked on all dentries in *ds with fs.renameMu locked for
// writing.
//
// ds is a pointer-to-pointer since defer evaluates its arguments immediately,
// but dentry slices are allocated lazily, and it's much easier to say "defer
-// fs.renameMuRUnlockAndCheckDrop(&ds)" than "defer func() {
-// fs.renameMuRUnlockAndCheckDrop(ds) }()" to work around this.
+// fs.renameMuRUnlockAndCheckCaching(&ds)" than "defer func() {
+// fs.renameMuRUnlockAndCheckCaching(ds) }()" to work around this.
// +checklocksrelease:fs.renameMu
-func (fs *filesystem) renameMuRUnlockAndCheckDrop(ctx context.Context, ds **[]*dentry) {
+func (fs *filesystem) renameMuRUnlockAndCheckCaching(ctx context.Context, ds **[]*dentry) {
fs.renameMu.RUnlock()
if *ds == nil {
return
}
- if len(**ds) != 0 {
- fs.renameMu.Lock()
- for _, d := range **ds {
- d.checkDropLocked(ctx)
- }
- fs.renameMu.Unlock()
- }
- putDentrySlice(*ds)
-}
-
-// +checklocksrelease:fs.renameMu
-func (fs *filesystem) renameMuUnlockAndCheckDrop(ctx context.Context, ds **[]*dentry) {
- if *ds == nil {
- fs.renameMu.Unlock()
- return
- }
for _, d := range **ds {
- d.checkDropLocked(ctx)
+ d.checkCachingLocked(ctx, false /* renameMuWriteLocked */)
}
- fs.renameMu.Unlock()
putDentrySlice(*ds)
}
@@ -700,7 +683,7 @@ func (fs *filesystem) AccessAt(ctx context.Context, rp *vfs.ResolvingPath, creds
}
var ds *[]*dentry
fs.renameMu.RLock()
- defer fs.renameMuRUnlockAndCheckDrop(ctx, &ds)
+ defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
return err
@@ -712,7 +695,7 @@ func (fs *filesystem) AccessAt(ctx context.Context, rp *vfs.ResolvingPath, creds
func (fs *filesystem) GetDentryAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.GetDentryOptions) (*vfs.Dentry, error) {
var ds *[]*dentry
fs.renameMu.RLock()
- defer fs.renameMuRUnlockAndCheckDrop(ctx, &ds)
+ defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
return nil, err
@@ -733,7 +716,7 @@ func (fs *filesystem) GetDentryAt(ctx context.Context, rp *vfs.ResolvingPath, op
func (fs *filesystem) GetParentDentryAt(ctx context.Context, rp *vfs.ResolvingPath) (*vfs.Dentry, error) {
var ds *[]*dentry
fs.renameMu.RLock()
- defer fs.renameMuRUnlockAndCheckDrop(ctx, &ds)
+ defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
start := rp.Start().Impl().(*dentry)
d, err := fs.walkParentDirLocked(ctx, rp, start, &ds)
if err != nil {
@@ -770,7 +753,7 @@ func (fs *filesystem) OpenAt(ctx context.Context, rp *vfs.ResolvingPath, opts vf
var ds *[]*dentry
fs.renameMu.RLock()
- defer fs.renameMuRUnlockAndCheckDrop(ctx, &ds)
+ defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
start := rp.Start().Impl().(*dentry)
if rp.Done() {
@@ -952,7 +935,7 @@ func (d *dentry) openLocked(ctx context.Context, rp *vfs.ResolvingPath, opts *vf
func (fs *filesystem) ReadlinkAt(ctx context.Context, rp *vfs.ResolvingPath) (string, error) {
var ds *[]*dentry
fs.renameMu.RLock()
- defer fs.renameMuRUnlockAndCheckDrop(ctx, &ds)
+ defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
return "", err
@@ -982,7 +965,7 @@ func (fs *filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts
func (fs *filesystem) StatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.StatOptions) (linux.Statx, error) {
var ds *[]*dentry
fs.renameMu.RLock()
- defer fs.renameMuRUnlockAndCheckDrop(ctx, &ds)
+ defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
return linux.Statx{}, err
@@ -1028,7 +1011,7 @@ func (fs *filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error
func (fs *filesystem) BoundEndpointAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.BoundEndpointOptions) (transport.BoundEndpoint, error) {
var ds *[]*dentry
fs.renameMu.RLock()
- defer fs.renameMuRUnlockAndCheckDrop(ctx, &ds)
+ defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
if _, err := fs.resolveLocked(ctx, rp, &ds); err != nil {
return nil, err
}
@@ -1039,7 +1022,7 @@ func (fs *filesystem) BoundEndpointAt(ctx context.Context, rp *vfs.ResolvingPath
func (fs *filesystem) ListXattrAt(ctx context.Context, rp *vfs.ResolvingPath, size uint64) ([]string, error) {
var ds *[]*dentry
fs.renameMu.RLock()
- defer fs.renameMuRUnlockAndCheckDrop(ctx, &ds)
+ defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
return nil, err
@@ -1055,7 +1038,7 @@ func (fs *filesystem) ListXattrAt(ctx context.Context, rp *vfs.ResolvingPath, si
func (fs *filesystem) GetXattrAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.GetXattrOptions) (string, error) {
var ds *[]*dentry
fs.renameMu.RLock()
- defer fs.renameMuRUnlockAndCheckDrop(ctx, &ds)
+ defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
d, err := fs.resolveLocked(ctx, rp, &ds)
if err != nil {
return "", err
diff --git a/pkg/sentry/fsimpl/verity/verity.go b/pkg/sentry/fsimpl/verity/verity.go
index 23841ecf7..d2526263c 100644
--- a/pkg/sentry/fsimpl/verity/verity.go
+++ b/pkg/sentry/fsimpl/verity/verity.go
@@ -23,10 +23,12 @@
// Lock order:
//
// filesystem.renameMu
-// dentry.dirMu
-// fileDescription.mu
-// filesystem.verityMu
-// dentry.hashMu
+// dentry.cachingMu
+// filesystem.cacheMu
+// dentry.dirMu
+// fileDescription.mu
+// filesystem.verityMu
+// dentry.hashMu
//
// Locking dentry.dirMu in multiple dentries requires that parent dentries are
// locked before child dentries, and that filesystem.renameMu is locked to
@@ -96,6 +98,9 @@ const (
// sizeOfStringInt32 is the size for a 32 bit integer stored as string in
// extended attributes. The maximum value of a 32 bit integer has 10 digits.
sizeOfStringInt32 = 10
+
+ // defaultMaxCachedDentries is the default limit of dentry cache.
+ defaultMaxCachedDentries = uint64(1000)
)
var (
@@ -106,9 +111,10 @@ var (
// Mount option names for verityfs.
const (
- moptLowerPath = "lower_path"
- moptRootHash = "root_hash"
- moptRootName = "root_name"
+ moptLowerPath = "lower_path"
+ moptRootHash = "root_hash"
+ moptRootName = "root_name"
+ moptDentryCacheLimit = "dentry_cache_limit"
)
// HashAlgorithm is a type specifying the algorithm used to hash the file
@@ -188,6 +194,17 @@ type filesystem struct {
// dentries.
renameMu sync.RWMutex `state:"nosave"`
+ // cachedDentries contains all dentries with 0 references. (Due to race
+ // conditions, it may also contain dentries with non-zero references.)
+ // cachedDentriesLen is the number of dentries in cachedDentries. These
+ // fields are protected by cacheMu.
+ cacheMu sync.Mutex `state:"nosave"`
+ cachedDentries dentryList
+ cachedDentriesLen uint64
+
+ // maxCachedDentries is the maximum size of filesystem.cachedDentries.
+ maxCachedDentries uint64
+
// verityMu synchronizes enabling verity files, protects files or
// directories from being enabled by different threads simultaneously.
// It also ensures that verity does not access files that are being
@@ -198,6 +215,10 @@ type filesystem struct {
// is for the whole file system to ensure that no more than one file is
// enabled the same time.
verityMu sync.RWMutex `state:"nosave"`
+
+ // released is nonzero once filesystem.Release has been called. It is accessed
+ // with atomic memory operations.
+ released int32
}
// InternalFilesystemOptions may be passed as
@@ -266,6 +287,16 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
delete(mopts, moptRootName)
rootName = root
}
+ maxCachedDentries := defaultMaxCachedDentries
+ if str, ok := mopts[moptDentryCacheLimit]; ok {
+ delete(mopts, moptDentryCacheLimit)
+ maxCD, err := strconv.ParseUint(str, 10, 64)
+ if err != nil {
+ ctx.Warningf("verity.FilesystemType.GetFilesystem: invalid dentry cache limit: %s=%s", moptDentryCacheLimit, str)
+ return nil, nil, linuxerr.EINVAL
+ }
+ maxCachedDentries = maxCD
+ }
// Check for unparsed options.
if len(mopts) != 0 {
@@ -339,12 +370,16 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
action: iopts.Action,
opts: opts.Data,
allowRuntimeEnable: iopts.AllowRuntimeEnable,
+ maxCachedDentries: maxCachedDentries,
}
fs.vfsfs.Init(vfsObj, &fstype, fs)
// Construct the root dentry.
d := fs.newDentry()
- d.refs = 1
+ // Set the root's reference count to 2. One reference is returned to
+ // the caller, and the other is held by fs to prevent the root from
+ // being "cached" and subsequently evicted.
+ d.refs = 2
lowerVD := vfs.MakeVirtualDentry(lowerMount, lowerMount.Root())
lowerVD.IncRef()
d.lowerVD = lowerVD
@@ -519,7 +554,16 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
// Release implements vfs.FilesystemImpl.Release.
func (fs *filesystem) Release(ctx context.Context) {
+ atomic.StoreInt32(&fs.released, 1)
fs.lowerMount.DecRef(ctx)
+
+ fs.renameMu.Lock()
+ fs.evictAllCachedDentriesLocked(ctx)
+ fs.renameMu.Unlock()
+
+ // An extra reference was held by the filesystem on the root to prevent
+ // it from being cached/evicted.
+ fs.rootDentry.DecRef(ctx)
}
// MountOptions implements vfs.FilesystemImpl.MountOptions.
@@ -533,6 +577,11 @@ func (fs *filesystem) MountOptions() string {
type dentry struct {
vfsd vfs.Dentry
+ // refs is the reference count. Each dentry holds a reference on its
+ // parent, even if disowned. When refs reaches 0, the dentry may be
+ // added to the cache or destroyed. If refs == -1, the dentry has
+ // already been destroyed. refs is accessed using atomic memory
+ // operations.
refs int64
// fs is the owning filesystem. fs is immutable.
@@ -587,13 +636,23 @@ type dentry struct {
// is protected by hashMu.
hashMu sync.RWMutex `state:"nosave"`
hash []byte
+
+ // cachingMu is used to synchronize concurrent dentry caching attempts on
+ // this dentry.
+ cachingMu sync.Mutex `state:"nosave"`
+
+ // If cached is true, dentryEntry links dentry into
+ // filesystem.cachedDentries. cached and dentryEntry are protected by
+ // cachingMu.
+ cached bool
+ dentryEntry
}
// newDentry creates a new dentry representing the given verity file. The
-// dentry initially has no references; it is the caller's responsibility to set
-// the dentry's reference count and/or call dentry.destroy() as appropriate.
-// The dentry is initially invalid in that it contains no underlying dentry;
-// the caller is responsible for setting them.
+// dentry initially has no references, but is not cached; it is the caller's
+// responsibility to set the dentry's reference count and/or call
+// dentry.destroy() as appropriate. The dentry is initially invalid in that it
+// contains no underlying dentry; the caller is responsible for setting them.
func (fs *filesystem) newDentry() *dentry {
d := &dentry{
fs: fs,
@@ -629,42 +688,23 @@ func (d *dentry) TryIncRef() bool {
// DecRef implements vfs.DentryImpl.DecRef.
func (d *dentry) DecRef(ctx context.Context) {
- r := atomic.AddInt64(&d.refs, -1)
- if d.LogRefs() {
- refsvfs2.LogDecRef(d, r)
- }
- if r == 0 {
- d.fs.renameMu.Lock()
- d.checkDropLocked(ctx)
- d.fs.renameMu.Unlock()
- } else if r < 0 {
- panic("verity.dentry.DecRef() called without holding a reference")
+ if d.decRefNoCaching() == 0 {
+ d.checkCachingLocked(ctx, false /* renameMuWriteLocked */)
}
}
-func (d *dentry) decRefLocked(ctx context.Context) {
+// decRefNoCaching decrements d's reference count without calling
+// d.checkCachingLocked, even if d's reference count reaches 0; callers are
+// responsible for ensuring that d.checkCachingLocked will be called later.
+func (d *dentry) decRefNoCaching() int64 {
r := atomic.AddInt64(&d.refs, -1)
if d.LogRefs() {
refsvfs2.LogDecRef(d, r)
}
- if r == 0 {
- d.checkDropLocked(ctx)
- } else if r < 0 {
- panic("verity.dentry.decRefLocked() called without holding a reference")
+ if r < 0 {
+ panic("verity.dentry.decRefNoCaching() called without holding a reference")
}
-}
-
-// checkDropLocked should be called after d's reference count becomes 0 or it
-// becomes deleted.
-func (d *dentry) checkDropLocked(ctx context.Context) {
- // Dentries with a positive reference count must be retained. Dentries
- // with a negative reference count have already been destroyed.
- if atomic.LoadInt64(&d.refs) != 0 {
- return
- }
- // Refs is still zero; destroy it.
- d.destroyLocked(ctx)
- return
+ return r
}
// destroyLocked destroys the dentry.
@@ -683,6 +723,12 @@ func (d *dentry) destroyLocked(ctx context.Context) {
panic("verity.dentry.destroyLocked() called with references on the dentry")
}
+ // Drop the reference held by d on its parent without recursively
+ // locking d.fs.renameMu.
+ if d.parent != nil && d.parent.decRefNoCaching() == 0 {
+ d.parent.checkCachingLocked(ctx, true /* renameMuWriteLocked */)
+ }
+
if d.lowerVD.Ok() {
d.lowerVD.DecRef(ctx)
}
@@ -695,7 +741,6 @@ func (d *dentry) destroyLocked(ctx context.Context) {
delete(d.parent.children, d.name)
}
d.parent.dirMu.Unlock()
- d.parent.decRefLocked(ctx)
}
refsvfs2.Unregister(d)
}
@@ -734,6 +779,140 @@ func (d *dentry) OnZeroWatches(context.Context) {
//TODO(b/159261227): Implement OnZeroWatches.
}
+// checkCachingLocked should be called after d's reference count becomes 0 or
+// it becomes disowned.
+//
+// For performance, checkCachingLocked can also be called after d's reference
+// count becomes non-zero, so that d can be removed from the LRU cache. This
+// may help in reducing the size of the cache and hence reduce evictions. Note
+// that this is not necessary for correctness.
+//
+// It may be called on a destroyed dentry. For example,
+// renameMu[R]UnlockAndCheckCaching may call checkCachingLocked multiple times
+// for the same dentry when the dentry is visited more than once in the same
+// operation. One of the calls may destroy the dentry, so subsequent calls will
+// do nothing.
+//
+// Preconditions: d.fs.renameMu must be locked for writing if
+// renameMuWriteLocked is true; it may be temporarily unlocked.
+func (d *dentry) checkCachingLocked(ctx context.Context, renameMuWriteLocked bool) {
+ d.cachingMu.Lock()
+ refs := atomic.LoadInt64(&d.refs)
+ if refs == -1 {
+ // Dentry has already been destroyed.
+ d.cachingMu.Unlock()
+ return
+ }
+ if refs > 0 {
+ // fs.cachedDentries is permitted to contain dentries with non-zero refs,
+ // which are skipped by fs.evictCachedDentryLocked() upon reaching the end
+ // of the LRU. But it is still beneficial to remove d from the cache as we
+ // are already holding d.cachingMu. Keeping a cleaner cache also reduces
+ // the number of evictions (which is expensive as it acquires fs.renameMu).
+ d.removeFromCacheLocked()
+ d.cachingMu.Unlock()
+ return
+ }
+
+ if atomic.LoadInt32(&d.fs.released) != 0 {
+ d.cachingMu.Unlock()
+ if !renameMuWriteLocked {
+ // Need to lock d.fs.renameMu to access d.parent. Lock it for writing as
+ // needed by d.destroyLocked() later.
+ d.fs.renameMu.Lock()
+ defer d.fs.renameMu.Unlock()
+ }
+ if d.parent != nil {
+ d.parent.dirMu.Lock()
+ delete(d.parent.children, d.name)
+ d.parent.dirMu.Unlock()
+ }
+ d.destroyLocked(ctx) // +checklocksforce: see above.
+ return
+ }
+
+ d.fs.cacheMu.Lock()
+ // If d is already cached, just move it to the front of the LRU.
+ if d.cached {
+ d.fs.cachedDentries.Remove(d)
+ d.fs.cachedDentries.PushFront(d)
+ d.fs.cacheMu.Unlock()
+ d.cachingMu.Unlock()
+ return
+ }
+ // Cache the dentry, then evict the least recently used cached dentry if
+ // the cache becomes over-full.
+ d.fs.cachedDentries.PushFront(d)
+ d.fs.cachedDentriesLen++
+ d.cached = true
+ shouldEvict := d.fs.cachedDentriesLen > d.fs.maxCachedDentries
+ d.fs.cacheMu.Unlock()
+ d.cachingMu.Unlock()
+
+ if shouldEvict {
+ if !renameMuWriteLocked {
+ // Need to lock d.fs.renameMu for writing as needed by
+ // d.evictCachedDentryLocked().
+ d.fs.renameMu.Lock()
+ defer d.fs.renameMu.Unlock()
+ }
+ d.fs.evictCachedDentryLocked(ctx) // +checklocksforce: see above.
+ }
+}
+
+// Preconditions: d.cachingMu must be locked.
+func (d *dentry) removeFromCacheLocked() {
+ if d.cached {
+ d.fs.cacheMu.Lock()
+ d.fs.cachedDentries.Remove(d)
+ d.fs.cachedDentriesLen--
+ d.fs.cacheMu.Unlock()
+ d.cached = false
+ }
+}
+
+// Precondition: fs.renameMu must be locked for writing; it may be temporarily
+// unlocked.
+// +checklocks:fs.renameMu
+func (fs *filesystem) evictAllCachedDentriesLocked(ctx context.Context) {
+ for fs.cachedDentriesLen != 0 {
+ fs.evictCachedDentryLocked(ctx)
+ }
+}
+
+// Preconditions:
+// * fs.renameMu must be locked for writing; it may be temporarily unlocked.
+// +checklocks:fs.renameMu
+func (fs *filesystem) evictCachedDentryLocked(ctx context.Context) {
+ fs.cacheMu.Lock()
+ victim := fs.cachedDentries.Back()
+ fs.cacheMu.Unlock()
+ if victim == nil {
+ // fs.cachedDentries may have become empty between when it was
+ // checked and when we locked fs.cacheMu.
+ return
+ }
+
+ victim.cachingMu.Lock()
+ victim.removeFromCacheLocked()
+ // 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 {
+ victim.cachingMu.Unlock()
+ return
+ }
+ if victim.parent != nil {
+ victim.parent.dirMu.Lock()
+ // Note that victim can't be a mount point (in any mount
+ // namespace), since VFS holds references on mount points.
+ fs.vfsfs.VirtualFilesystem().InvalidateDentry(ctx, &victim.vfsd)
+ delete(victim.parent.children, victim.name)
+ victim.parent.dirMu.Unlock()
+ }
+ victim.cachingMu.Unlock()
+ victim.destroyLocked(ctx) // +checklocksforce: owned as precondition, victim.fs == fs.
+}
+
func (d *dentry) isSymlink() bool {
return atomic.LoadUint32(&d.mode)&linux.S_IFMT == linux.S_IFLNK
}
diff --git a/pkg/sentry/fsimpl/verity/verity_state_autogen.go b/pkg/sentry/fsimpl/verity/verity_state_autogen.go
index dba01a68e..302823121 100644
--- a/pkg/sentry/fsimpl/verity/verity_state_autogen.go
+++ b/pkg/sentry/fsimpl/verity/verity_state_autogen.go
@@ -6,6 +6,62 @@ import (
"gvisor.dev/gvisor/pkg/state"
)
+func (l *dentryList) StateTypeName() string {
+ return "pkg/sentry/fsimpl/verity.dentryList"
+}
+
+func (l *dentryList) StateFields() []string {
+ return []string{
+ "head",
+ "tail",
+ }
+}
+
+func (l *dentryList) beforeSave() {}
+
+// +checklocksignore
+func (l *dentryList) StateSave(stateSinkObject state.Sink) {
+ l.beforeSave()
+ stateSinkObject.Save(0, &l.head)
+ stateSinkObject.Save(1, &l.tail)
+}
+
+func (l *dentryList) afterLoad() {}
+
+// +checklocksignore
+func (l *dentryList) StateLoad(stateSourceObject state.Source) {
+ stateSourceObject.Load(0, &l.head)
+ stateSourceObject.Load(1, &l.tail)
+}
+
+func (e *dentryEntry) StateTypeName() string {
+ return "pkg/sentry/fsimpl/verity.dentryEntry"
+}
+
+func (e *dentryEntry) StateFields() []string {
+ return []string{
+ "next",
+ "prev",
+ }
+}
+
+func (e *dentryEntry) beforeSave() {}
+
+// +checklocksignore
+func (e *dentryEntry) StateSave(stateSinkObject state.Sink) {
+ e.beforeSave()
+ stateSinkObject.Save(0, &e.next)
+ stateSinkObject.Save(1, &e.prev)
+}
+
+func (e *dentryEntry) afterLoad() {}
+
+// +checklocksignore
+func (e *dentryEntry) StateLoad(stateSourceObject state.Source) {
+ stateSourceObject.Load(0, &e.next)
+ stateSourceObject.Load(1, &e.prev)
+}
+
func (fstype *FilesystemType) StateTypeName() string {
return "pkg/sentry/fsimpl/verity.FilesystemType"
}
@@ -41,6 +97,10 @@ func (fs *filesystem) StateFields() []string {
"alg",
"action",
"opts",
+ "cachedDentries",
+ "cachedDentriesLen",
+ "maxCachedDentries",
+ "released",
}
}
@@ -57,6 +117,10 @@ func (fs *filesystem) StateSave(stateSinkObject state.Sink) {
stateSinkObject.Save(5, &fs.alg)
stateSinkObject.Save(6, &fs.action)
stateSinkObject.Save(7, &fs.opts)
+ stateSinkObject.Save(8, &fs.cachedDentries)
+ stateSinkObject.Save(9, &fs.cachedDentriesLen)
+ stateSinkObject.Save(10, &fs.maxCachedDentries)
+ stateSinkObject.Save(11, &fs.released)
}
func (fs *filesystem) afterLoad() {}
@@ -71,6 +135,10 @@ func (fs *filesystem) StateLoad(stateSourceObject state.Source) {
stateSourceObject.Load(5, &fs.alg)
stateSourceObject.Load(6, &fs.action)
stateSourceObject.Load(7, &fs.opts)
+ stateSourceObject.Load(8, &fs.cachedDentries)
+ stateSourceObject.Load(9, &fs.cachedDentriesLen)
+ stateSourceObject.Load(10, &fs.maxCachedDentries)
+ stateSourceObject.Load(11, &fs.released)
}
func (i *InternalFilesystemOptions) StateTypeName() string {
@@ -132,6 +200,8 @@ func (d *dentry) StateFields() []string {
"lowerMerkleVD",
"symlinkTarget",
"hash",
+ "cached",
+ "dentryEntry",
}
}
@@ -156,6 +226,8 @@ func (d *dentry) StateSave(stateSinkObject state.Sink) {
stateSinkObject.Save(13, &d.lowerMerkleVD)
stateSinkObject.Save(14, &d.symlinkTarget)
stateSinkObject.Save(15, &d.hash)
+ stateSinkObject.Save(16, &d.cached)
+ stateSinkObject.Save(17, &d.dentryEntry)
}
// +checklocksignore
@@ -176,6 +248,8 @@ func (d *dentry) StateLoad(stateSourceObject state.Source) {
stateSourceObject.Load(13, &d.lowerMerkleVD)
stateSourceObject.Load(14, &d.symlinkTarget)
stateSourceObject.Load(15, &d.hash)
+ stateSourceObject.Load(16, &d.cached)
+ stateSourceObject.Load(17, &d.dentryEntry)
stateSourceObject.AfterLoad(d.afterLoad)
}
@@ -232,6 +306,8 @@ func (fd *fileDescription) StateLoad(stateSourceObject state.Source) {
}
func init() {
+ state.Register((*dentryList)(nil))
+ state.Register((*dentryEntry)(nil))
state.Register((*FilesystemType)(nil))
state.Register((*filesystem)(nil))
state.Register((*InternalFilesystemOptions)(nil))
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-20 09:32:14 +0000