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authorgVisor bot <gvisor-bot@google.com>2021-07-13 01:36:04 +0000
committergVisor bot <gvisor-bot@google.com>2021-07-13 01:36:04 +0000
commit06f349011627d6298168ceac919e27cb166675d4 (patch)
treedf2b179bb06b09baee6d2cd47c714d03ae6d75f2 /pkg/sentry/fsimpl/kernfs
parent289efe127e1f04f4fbb0c2a46050a6cd9c9f3b9b (diff)
parent520795aaad701854e9ffe84de1108954cf2b77f8 (diff)
Merge release-20210705.0-15-g520795aaa (automated)
Diffstat (limited to 'pkg/sentry/fsimpl/kernfs')
-rw-r--r--pkg/sentry/fsimpl/kernfs/kernfs.go54
-rw-r--r--pkg/sentry/fsimpl/kernfs/kernfs_state_autogen.go6
-rw-r--r--pkg/sentry/fsimpl/kernfs/static_directory_refs.go2
-rw-r--r--pkg/sentry/fsimpl/kernfs/synthetic_directory_refs.go2
4 files changed, 44 insertions, 20 deletions
diff --git a/pkg/sentry/fsimpl/kernfs/kernfs.go b/pkg/sentry/fsimpl/kernfs/kernfs.go
index 6f699c9cd..0e2867d49 100644
--- a/pkg/sentry/fsimpl/kernfs/kernfs.go
+++ b/pkg/sentry/fsimpl/kernfs/kernfs.go
@@ -52,7 +52,7 @@
// vfs.VirtualFilesystem.mountMu
// vfs.Dentry.mu
// (inode implementation locks, if any)
-// kernfs.Filesystem.droppedDentriesMu
+// kernfs.Filesystem.deferredDecRefsMu
package kernfs
import (
@@ -76,12 +76,12 @@ import (
type Filesystem struct {
vfsfs vfs.Filesystem
- droppedDentriesMu sync.Mutex `state:"nosave"`
+ deferredDecRefsMu sync.Mutex `state:"nosave"`
- // droppedDentries is a list of dentries waiting to be DecRef()ed. This is
+ // deferredDecRefs is a list of dentries waiting to be DecRef()ed. This is
// used to defer dentry destruction until mu can be acquired for
- // writing. Protected by droppedDentriesMu.
- droppedDentries []*Dentry
+ // writing. Protected by deferredDecRefsMu.
+ deferredDecRefs []refsvfs2.RefCounter
// mu synchronizes the lifetime of Dentries on this filesystem. Holding it
// for reading guarantees continued existence of any resolved dentries, but
@@ -131,25 +131,49 @@ type Filesystem struct {
// deferDecRef defers dropping a dentry ref until the next call to
// processDeferredDecRefs{,Locked}. See comment on Filesystem.mu.
// This may be called while Filesystem.mu or Dentry.dirMu is locked.
-func (fs *Filesystem) deferDecRef(d *Dentry) {
- fs.droppedDentriesMu.Lock()
- fs.droppedDentries = append(fs.droppedDentries, d)
- fs.droppedDentriesMu.Unlock()
+func (fs *Filesystem) deferDecRef(d refsvfs2.RefCounter) {
+ fs.deferredDecRefsMu.Lock()
+ fs.deferredDecRefs = append(fs.deferredDecRefs, d)
+ fs.deferredDecRefsMu.Unlock()
+}
+
+// SafeDecRefFD safely DecRef the FileDescription making sure DecRef is deferred
+// in case Filesystem.mu is held. See comment on Filesystem.mu.
+func (fs *Filesystem) SafeDecRefFD(ctx context.Context, fd *vfs.FileDescription) {
+ if d, ok := fd.Dentry().Impl().(*Dentry); ok && d.fs == fs {
+ // Only defer if dentry belongs to this filesystem, since locks cannot cross
+ // filesystems.
+ fs.deferDecRef(fd)
+ return
+ }
+ fd.DecRef(ctx)
+}
+
+// SafeDecRef safely DecRef the virtual dentry making sure DecRef is deferred
+// in case Filesystem.mu is held. See comment on Filesystem.mu.
+func (fs *Filesystem) SafeDecRef(ctx context.Context, vd vfs.VirtualDentry) {
+ if d, ok := vd.Dentry().Impl().(*Dentry); ok && d.fs == fs {
+ // Only defer if dentry belongs to this filesystem, since locks cannot cross
+ // filesystems.
+ fs.deferDecRef(&vd)
+ return
+ }
+ vd.DecRef(ctx)
}
// processDeferredDecRefs calls vfs.Dentry.DecRef on all dentries in the
-// droppedDentries list. See comment on Filesystem.mu.
+// deferredDecRefs list. See comment on Filesystem.mu.
//
// Precondition: Filesystem.mu or Dentry.dirMu must NOT be locked.
func (fs *Filesystem) processDeferredDecRefs(ctx context.Context) {
- fs.droppedDentriesMu.Lock()
- for _, d := range fs.droppedDentries {
- // Defer the DecRef call so that we are not holding droppedDentriesMu
+ fs.deferredDecRefsMu.Lock()
+ for _, d := range fs.deferredDecRefs {
+ // Defer the DecRef call so that we are not holding deferredDecRefsMu
// when DecRef is called.
defer d.DecRef(ctx)
}
- fs.droppedDentries = fs.droppedDentries[:0] // Keep slice memory for reuse.
- fs.droppedDentriesMu.Unlock()
+ fs.deferredDecRefs = fs.deferredDecRefs[:0] // Keep slice memory for reuse.
+ fs.deferredDecRefsMu.Unlock()
}
// VFSFilesystem returns the generic vfs filesystem object.
diff --git a/pkg/sentry/fsimpl/kernfs/kernfs_state_autogen.go b/pkg/sentry/fsimpl/kernfs/kernfs_state_autogen.go
index 5b8d033ec..f8add23f8 100644
--- a/pkg/sentry/fsimpl/kernfs/kernfs_state_autogen.go
+++ b/pkg/sentry/fsimpl/kernfs/kernfs_state_autogen.go
@@ -602,7 +602,7 @@ func (fs *Filesystem) StateTypeName() string {
func (fs *Filesystem) StateFields() []string {
return []string{
"vfsfs",
- "droppedDentries",
+ "deferredDecRefs",
"nextInoMinusOne",
"cachedDentries",
"cachedDentriesLen",
@@ -617,7 +617,7 @@ func (fs *Filesystem) beforeSave() {}
func (fs *Filesystem) StateSave(stateSinkObject state.Sink) {
fs.beforeSave()
stateSinkObject.Save(0, &fs.vfsfs)
- stateSinkObject.Save(1, &fs.droppedDentries)
+ stateSinkObject.Save(1, &fs.deferredDecRefs)
stateSinkObject.Save(2, &fs.nextInoMinusOne)
stateSinkObject.Save(3, &fs.cachedDentries)
stateSinkObject.Save(4, &fs.cachedDentriesLen)
@@ -630,7 +630,7 @@ func (fs *Filesystem) afterLoad() {}
// +checklocksignore
func (fs *Filesystem) StateLoad(stateSourceObject state.Source) {
stateSourceObject.Load(0, &fs.vfsfs)
- stateSourceObject.Load(1, &fs.droppedDentries)
+ stateSourceObject.Load(1, &fs.deferredDecRefs)
stateSourceObject.Load(2, &fs.nextInoMinusOne)
stateSourceObject.Load(3, &fs.cachedDentries)
stateSourceObject.Load(4, &fs.cachedDentriesLen)
diff --git a/pkg/sentry/fsimpl/kernfs/static_directory_refs.go b/pkg/sentry/fsimpl/kernfs/static_directory_refs.go
index d6180daa3..69534a2d2 100644
--- a/pkg/sentry/fsimpl/kernfs/static_directory_refs.go
+++ b/pkg/sentry/fsimpl/kernfs/static_directory_refs.go
@@ -81,7 +81,7 @@ func (r *StaticDirectoryRefs) IncRef() {
}
}
-// TryIncRef implements refs.RefCounter.TryIncRef.
+// TryIncRef implements refs.TryRefCounter.TryIncRef.
//
// To do this safely without a loop, a speculative reference is first acquired
// on the object. This allows multiple concurrent TryIncRef calls to distinguish
diff --git a/pkg/sentry/fsimpl/kernfs/synthetic_directory_refs.go b/pkg/sentry/fsimpl/kernfs/synthetic_directory_refs.go
index c428cdead..3c5fdf15e 100644
--- a/pkg/sentry/fsimpl/kernfs/synthetic_directory_refs.go
+++ b/pkg/sentry/fsimpl/kernfs/synthetic_directory_refs.go
@@ -81,7 +81,7 @@ func (r *syntheticDirectoryRefs) IncRef() {
}
}
-// TryIncRef implements refs.RefCounter.TryIncRef.
+// TryIncRef implements refs.TryRefCounter.TryIncRef.
//
// To do this safely without a loop, a speculative reference is first acquired
// on the object. This allows multiple concurrent TryIncRef calls to distinguish
generated by cgit v1.2.3 (git 2.39.1) at 2025-04-01 05:54:41 +0000