Merge release-20210419.0-12-gc2955339d (automated)

1 files changed, 0 insertions, 386 deletions

diff --git a/pkg/sentry/fsimpl/gofer/revalidate.go b/pkg/sentry/fsimpl/gofer/revalidate.go
deleted file mode 100644
index 8f81f0822..000000000
--- a/pkg/sentry/fsimpl/gofer/revalidate.go
+++ /dev/null
@@ -1,386 +0,0 @@
-// Copyright 2021 The gVisor Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package gofer
-
-import (
-	"gvisor.dev/gvisor/pkg/context"
-	"gvisor.dev/gvisor/pkg/sentry/vfs"
-	"gvisor.dev/gvisor/pkg/sync"
-)
-
-type errPartialRevalidation struct{}
-
-// Error implements error.Error.
-func (errPartialRevalidation) Error() string {
-	return "partial revalidation"
-}
-
-type errRevalidationStepDone struct{}
-
-// Error implements error.Error.
-func (errRevalidationStepDone) Error() string {
-	return "stop revalidation"
-}
-
-// revalidatePath checks cached dentries for external modification. File
-// attributes are refreshed and cache is invalidated in case the dentry has been
-// deleted, or a new file/directory created in its place.
-//
-// Revalidation stops at symlinks and mount points. The caller is responsible
-// for revalidating again after symlinks are resolved and after changing to
-// different mounts.
-//
-// Preconditions:
-// * fs.renameMu must be locked.
-func (fs *filesystem) revalidatePath(ctx context.Context, rpOrig *vfs.ResolvingPath, start *dentry, ds **[]*dentry) error {
-	// Revalidation is done even if start is synthetic in case the path is
-	// something like: ../non_synthetic_file.
-	if fs.opts.interop != InteropModeShared {
-		return nil
-	}
-
-	// Copy resolving path to walk the path for revalidation.
-	rp := rpOrig.Copy()
-	err := fs.revalidate(ctx, rp, start, rp.Done, ds)
-	rp.Release(ctx)
-	return err
-}
-
-// revalidateParentDir does the same as revalidatePath, but stops at the parent.
-//
-// Preconditions:
-// * fs.renameMu must be locked.
-func (fs *filesystem) revalidateParentDir(ctx context.Context, rpOrig *vfs.ResolvingPath, start *dentry, ds **[]*dentry) error {
-	// Revalidation is done even if start is synthetic in case the path is
-	// something like: ../non_synthetic_file and parent is non synthetic.
-	if fs.opts.interop != InteropModeShared {
-		return nil
-	}
-
-	// Copy resolving path to walk the path for revalidation.
-	rp := rpOrig.Copy()
-	err := fs.revalidate(ctx, rp, start, rp.Final, ds)
-	rp.Release(ctx)
-	return err
-}
-
-// revalidateOne does the same as revalidatePath, but checks a single dentry.
-//
-// Preconditions:
-// * fs.renameMu must be locked.
-func (fs *filesystem) revalidateOne(ctx context.Context, vfsObj *vfs.VirtualFilesystem, parent *dentry, name string, ds **[]*dentry) error {
-	// Skip revalidation for interop mode different than InteropModeShared or
-	// if the parent is synthetic (child must be synthetic too, but it cannot be
-	// replaced without first replacing the parent).
-	if parent.cachedMetadataAuthoritative() {
-		return nil
-	}
-
-	parent.dirMu.Lock()
-	child, ok := parent.children[name]
-	parent.dirMu.Unlock()
-	if !ok {
-		return nil
-	}
-
-	state := makeRevalidateState(parent)
-	defer state.release()
-
-	state.add(name, child)
-	return fs.revalidateHelper(ctx, vfsObj, state, ds)
-}
-
-// revalidate revalidates path components in rp until done returns true, or
-// until a mount point or symlink is reached. It may send multiple MultiGetAttr
-// calls to the gofer to handle ".." in the path.
-//
-// Preconditions:
-// * fs.renameMu must be locked.
-// * InteropModeShared is in effect.
-func (fs *filesystem) revalidate(ctx context.Context, rp *vfs.ResolvingPath, start *dentry, done func() bool, ds **[]*dentry) error {
-	state := makeRevalidateState(start)
-	defer state.release()
-
-	// Skip synthetic dentries because the start dentry cannot be replaced in case
-	// it has been created in the remote file system.
-	if !start.isSynthetic() {
-		state.add("", start)
-	}
-
-done:
-	for cur := start; !done(); {
-		var err error
-		cur, err = fs.revalidateStep(ctx, rp, cur, state)
-		if err != nil {
-			switch err.(type) {
-			case errPartialRevalidation:
-				if err := fs.revalidateHelper(ctx, rp.VirtualFilesystem(), state, ds); err != nil {
-					return err
-				}
-
-				// Reset state to release any remaining locks and restart from where
-				// stepping stopped.
-				state.reset()
-				state.start = cur
-
-				// Skip synthetic dentries because the start dentry cannot be replaced in
-				// case it has been created in the remote file system.
-				if !cur.isSynthetic() {
-					state.add("", cur)
-				}
-
-			case errRevalidationStepDone:
-				break done
-
-			default:
-				return err
-			}
-		}
-	}
-	return fs.revalidateHelper(ctx, rp.VirtualFilesystem(), state, ds)
-}
-
-// revalidateStep walks one element of the path and updates revalidationState
-// with the dentry if needed. It may also stop the stepping or ask for a
-// partial revalidation. Partial revalidation requires the caller to revalidate
-// the current revalidationState, release all locks, and resume stepping.
-// In case a symlink is hit, revalidation stops and the caller is responsible
-// for calling revalidate again after the symlink is resolved. Revalidation may
-// also stop for other reasons, like hitting a child not in the cache.
-//
-// Returns:
-// * (dentry, nil): step worked, continue stepping.`
-// * (dentry, errPartialRevalidation): revalidation should be done with the
-//     state gathered so far. Then continue stepping with the remainder of the
-//     path, starting at `dentry`.
-// * (nil, errRevalidationStepDone): revalidation doesn't need to step any
-//     further. It hit a symlink, a mount point, or an uncached dentry.
-//
-// Preconditions:
-// * fs.renameMu must be locked.
-// * !rp.Done().
-// * InteropModeShared is in effect (assumes no negative dentries).
-func (fs *filesystem) revalidateStep(ctx context.Context, rp *vfs.ResolvingPath, d *dentry, state *revalidateState) (*dentry, error) {
-	switch name := rp.Component(); name {
-	case ".":
-		// Do nothing.
-
-	case "..":
-		// Partial revalidation is required when ".." is hit because metadata locks
-		// can only be acquired from parent to child to avoid deadlocks.
-		if isRoot, err := rp.CheckRoot(ctx, &d.vfsd); err != nil {
-			return nil, errRevalidationStepDone{}
-		} else if isRoot || d.parent == nil {
-			rp.Advance()
-			return d, errPartialRevalidation{}
-		}
-		// We must assume that d.parent is correct, because if d has been moved
-		// elsewhere in the remote filesystem so that its parent has changed,
-		// we have no way of determining its new parent's location in the
-		// filesystem.
-		//
-		// Call rp.CheckMount() before updating d.parent's metadata, since if
-		// we traverse to another mount then d.parent's metadata is irrelevant.
-		if err := rp.CheckMount(ctx, &d.parent.vfsd); err != nil {
-			return nil, errRevalidationStepDone{}
-		}
-		rp.Advance()
-		return d.parent, errPartialRevalidation{}
-
-	default:
-		d.dirMu.Lock()
-		child, ok := d.children[name]
-		d.dirMu.Unlock()
-		if !ok {
-			// child is not cached, no need to validate any further.
-			return nil, errRevalidationStepDone{}
-		}
-
-		state.add(name, child)
-
-		// Symlink must be resolved before continuing with revalidation.
-		if child.isSymlink() {
-			return nil, errRevalidationStepDone{}
-		}
-
-		d = child
-	}
-
-	rp.Advance()
-	return d, nil
-}
-
-// revalidateHelper calls the gofer to stat all dentries in `state`. It will
-// update or invalidate dentries in the cache based on the result.
-//
-// Preconditions:
-// * fs.renameMu must be locked.
-// * InteropModeShared is in effect.
-func (fs *filesystem) revalidateHelper(ctx context.Context, vfsObj *vfs.VirtualFilesystem, state *revalidateState, ds **[]*dentry) error {
-	if len(state.names) == 0 {
-		return nil
-	}
-	// Lock metadata on all dentries *before* getting attributes for them.
-	state.lockAllMetadata()
-	stats, err := state.start.file.multiGetAttr(ctx, state.names)
-	if err != nil {
-		return err
-	}
-
-	i := -1
-	for d := state.popFront(); d != nil; d = state.popFront() {
-		i++
-		found := i < len(stats)
-		if i == 0 && len(state.names[0]) == 0 {
-			if found && !d.isSynthetic() {
-				// First dentry is where the search is starting, just update attributes
-				// since it cannot be replaced.
-				d.updateFromP9AttrsLocked(stats[i].Valid, &stats[i].Attr)
-			}
-			d.metadataMu.Unlock()
-			continue
-		}
-
-		// Note that synthetic dentries will always fails the comparison check
-		// below.
-		if !found || d.qidPath != stats[i].QID.Path {
-			d.metadataMu.Unlock()
-			if !found && d.isSynthetic() {
-				// We have a synthetic file, and no remote file has arisen to replace
-				// it.
-				return nil
-			}
-			// The file at this path has changed or no longer exists. Mark the
-			// dentry invalidated, and re-evaluate its caching status (i.e. if it
-			// has 0 references, drop it). The dentry will be reloaded next time it's
-			// accessed.
-			vfsObj.InvalidateDentry(ctx, &d.vfsd)
-
-			name := state.names[i]
-			d.parent.dirMu.Lock()
-
-			if d.isSynthetic() {
-				// Normally we don't mark invalidated dentries as deleted since
-				// they may still exist (but at a different path), and also for
-				// consistency with Linux. However, synthetic files are guaranteed
-				// to become unreachable if their dentries are invalidated, so
-				// treat their invalidation as deletion.
-				d.setDeleted()
-				d.decRefNoCaching()
-				*ds = appendDentry(*ds, d)
-
-				d.parent.syntheticChildren--
-				d.parent.dirents = nil
-			}
-
-			// Since the dirMu was released and reacquired, re-check that the
-			// parent's child with this name is still the same. Do not touch it if
-			// it has been replaced with a different one.
-			if child := d.parent.children[name]; child == d {
-				// Invalidate dentry so it gets reloaded next time it's accessed.
-				delete(d.parent.children, name)
-			}
-			d.parent.dirMu.Unlock()
-
-			return nil
-		}
-
-		// The file at this path hasn't changed. Just update cached metadata.
-		d.updateFromP9AttrsLocked(stats[i].Valid, &stats[i].Attr)
-		d.metadataMu.Unlock()
-	}
-
-	return nil
-}
-
-// revalidateStatePool caches revalidateState instances to save array
-// allocations for dentries and names.
-var revalidateStatePool = sync.Pool{
-	New: func() interface{} {
-		return &revalidateState{}
-	},
-}
-
-// revalidateState keeps state related to a revalidation request. It keeps track
-// of {name, dentry} list being revalidated, as well as metadata locks on the
-// dentries. The list must be in ancestry order, in other words `n` must be
-// `n-1` child.
-type revalidateState struct {
-	// start is the dentry where to start the attributes search.
-	start *dentry
-
-	// List of names of entries to refresh attributes. Names length must be the
-	// same as detries length. They are kept in separate slices because names is
-	// used to call File.MultiGetAttr().
-	names []string
-
-	// dentries is the list of dentries that correspond to the names above.
-	// dentry.metadataMu is acquired as each dentry is added to this list.
-	dentries []*dentry
-
-	// locked indicates if metadata lock has been acquired on dentries.
-	locked bool
-}
-
-func makeRevalidateState(start *dentry) *revalidateState {
-	r := revalidateStatePool.Get().(*revalidateState)
-	r.start = start
-	return r
-}
-
-// release must be called after the caller is done with this object. It releases
-// all metadata locks and resources.
-func (r *revalidateState) release() {
-	r.reset()
-	revalidateStatePool.Put(r)
-}
-
-// Preconditions:
-// * d is a descendant of all dentries in r.dentries.
-func (r *revalidateState) add(name string, d *dentry) {
-	r.names = append(r.names, name)
-	r.dentries = append(r.dentries, d)
-}
-
-func (r *revalidateState) lockAllMetadata() {
-	for _, d := range r.dentries {
-		d.metadataMu.Lock()
-	}
-	r.locked = true
-}
-
-func (r *revalidateState) popFront() *dentry {
-	if len(r.dentries) == 0 {
-		return nil
-	}
-	d := r.dentries[0]
-	r.dentries = r.dentries[1:]
-	return d
-}
-
-// reset releases all metadata locks and resets all fields to allow this
-// instance to be reused.
-func (r *revalidateState) reset() {
-	if r.locked {
-		// Unlock any remaining dentries.
-		for _, d := range r.dentries {
-			d.metadataMu.Unlock()
-		}
-		r.locked = false
-	}
-	r.start = nil
-	r.names = r.names[:0]
-	r.dentries = r.dentries[:0]
-}