diff options
Diffstat (limited to 'pkg/sentry/fsimpl/gofer/gofer.go')
| -rw-r--r-- | pkg/sentry/fsimpl/gofer/gofer.go | 90 |
1 files changed, 83 insertions, 7 deletions
diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go index f7c94cce1..604c6d7cd 100644 --- a/pkg/sentry/fsimpl/gofer/gofer.go +++ b/pkg/sentry/fsimpl/gofer/gofer.go @@ -46,6 +46,8 @@ import ( "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/log" "gvisor.dev/gvisor/pkg/p9" + refs_vfs1 "gvisor.dev/gvisor/pkg/refs" + "gvisor.dev/gvisor/pkg/refsvfs2" "gvisor.dev/gvisor/pkg/sentry/fs/fsutil" fslock "gvisor.dev/gvisor/pkg/sentry/fs/lock" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" @@ -109,8 +111,8 @@ type filesystem struct { // 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 renameMu. + // cachedDentriesLen is the number of dentries in cachedDentries. These fields + // are protected by renameMu. cachedDentries dentryList cachedDentriesLen uint64 @@ -134,6 +136,10 @@ type filesystem struct { // savedDentryRW records open read/write handles during save/restore. savedDentryRW map[*dentry]savedDentryRW + + // released is nonzero once filesystem.Release has been called. It is accessed + // with atomic memory operations. + released int32 } // +stateify savable @@ -454,9 +460,8 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt return nil, nil, err } // Set the root's reference count to 2. One reference is returned to the - // caller, and the other is deliberately leaked to prevent the root from - // being "cached" and subsequently evicted. Its resources will still be - // cleaned up by fs.Release(). + // caller, and the other is held by fs to prevent the root from being "cached" + // and subsequently evicted. root.refs = 2 fs.root = root @@ -526,15 +531,16 @@ func (fs *filesystem) dial(ctx context.Context) error { // Release implements vfs.FilesystemImpl.Release. func (fs *filesystem) Release(ctx context.Context) { - mf := fs.mfp.MemoryFile() + atomic.StoreInt32(&fs.released, 1) + mf := fs.mfp.MemoryFile() fs.syncMu.Lock() for d := range fs.syncableDentries { d.handleMu.Lock() d.dataMu.Lock() if h := d.writeHandleLocked(); h.isOpen() { // Write dirty cached data to the remote file. - if err := fsutil.SyncDirtyAll(ctx, &d.cache, &d.dirty, d.size, fs.mfp.MemoryFile(), h.writeFromBlocksAt); err != nil { + if err := fsutil.SyncDirtyAll(ctx, &d.cache, &d.dirty, d.size, mf, h.writeFromBlocksAt); err != nil { log.Warningf("gofer.filesystem.Release: failed to flush dentry: %v", err) } // TODO(jamieliu): Do we need to flushf/fsync d? @@ -555,6 +561,21 @@ func (fs *filesystem) Release(ctx context.Context) { // fs. fs.syncMu.Unlock() + // If leak checking is enabled, release all outstanding references in the + // filesystem. We deliberately avoid doing this outside of leak checking; we + // have released all external resources above rather than relying on dentry + // destructors. + if refs_vfs1.GetLeakMode() != refs_vfs1.NoLeakChecking { + fs.renameMu.Lock() + fs.root.releaseSyntheticRecursiveLocked(ctx) + 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.root.DecRef(ctx) + } + if !fs.iopts.LeakConnection { // Close the connection to the server. This implicitly clunks all fids. fs.client.Close() @@ -563,6 +584,31 @@ func (fs *filesystem) Release(ctx context.Context) { fs.vfsfs.VirtualFilesystem().PutAnonBlockDevMinor(fs.devMinor) } +// releaseSyntheticRecursiveLocked traverses the tree with root d and decrements +// the reference count on every synthetic dentry. Synthetic dentries have one +// reference for existence that should be dropped during filesystem.Release. +// +// Precondition: d.fs.renameMu is locked. +func (d *dentry) releaseSyntheticRecursiveLocked(ctx context.Context) { + if d.isSynthetic() { + d.decRefLocked() + d.checkCachingLocked(ctx) + } + if d.isDir() { + var children []*dentry + d.dirMu.Lock() + for _, child := range d.children { + children = append(children, child) + } + d.dirMu.Unlock() + for _, child := range children { + if child != nil { + child.releaseSyntheticRecursiveLocked(ctx) + } + } + } +} + // dentry implements vfs.DentryImpl. // // +stateify savable @@ -815,6 +861,9 @@ func (fs *filesystem) newDentry(ctx context.Context, file p9file, qid p9.QID, ma d.nlink = uint32(attr.NLink) } d.vfsd.Init(d) + if refsvfs2.LeakCheckEnabled() { + refsvfs2.Register(d, "gofer.dentry") + } fs.syncMu.Lock() fs.syncableDentries[d] = struct{}{} @@ -1210,6 +1259,11 @@ func (d *dentry) decRefLocked() { } } +// LeakMessage implements refsvfs2.CheckedObject.LeakMessage. +func (d *dentry) LeakMessage() string { + return fmt.Sprintf("[gofer.dentry %p] reference count of %d instead of -1", d, atomic.LoadInt64(&d.refs)) +} + // InotifyWithParent implements vfs.DentryImpl.InotifyWithParent. func (d *dentry) InotifyWithParent(ctx context.Context, events, cookie uint32, et vfs.EventType) { if d.isDir() { @@ -1292,6 +1346,16 @@ func (d *dentry) checkCachingLocked(ctx context.Context) { if d.watches.Size() > 0 { return } + + if atomic.LoadInt32(&d.fs.released) != 0 { + if d.parent != nil { + d.parent.dirMu.Lock() + delete(d.parent.children, d.name) + d.parent.dirMu.Unlock() + } + d.destroyLocked(ctx) + } + // If d is already cached, just move it to the front of the LRU. if d.cached { d.fs.cachedDentries.Remove(d) @@ -1310,6 +1374,14 @@ func (d *dentry) checkCachingLocked(ctx context.Context) { } } +// Precondition: fs.renameMu must be locked for writing; it may be temporarily +// unlocked. +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. // * fs.cachedDentriesLen != 0. @@ -1422,6 +1494,10 @@ func (d *dentry) destroyLocked(ctx context.Context) { panic("gofer.dentry.DecRef() called without holding a reference") } } + + if refsvfs2.LeakCheckEnabled() { + refsvfs2.Unregister(d, "gofer.dentry") + } } func (d *dentry) isDeleted() bool { |