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-rw-r--r--pkg/sentry/fs/attr.go19
-rw-r--r--pkg/sentry/fs/dirent.go2
-rw-r--r--pkg/sentry/fs/fsutil/inode_cached.go41
-rw-r--r--pkg/sentry/fs/gofer/cache_policy.go64
-rw-r--r--pkg/sentry/fs/gofer/gofer_test.go95
-rw-r--r--pkg/sentry/fs/gofer/session.go6
-rw-r--r--pkg/sentry/fs/mock.go2
-rw-r--r--pkg/sentry/fs/mount.go13
-rw-r--r--pkg/sentry/fs/mount_overlay.go20
-rw-r--r--pkg/sentry/fs/tty/fs.go2
10 files changed, 192 insertions, 72 deletions
diff --git a/pkg/sentry/fs/attr.go b/pkg/sentry/fs/attr.go
index 4178f18b2..091f4ac63 100644
--- a/pkg/sentry/fs/attr.go
+++ b/pkg/sentry/fs/attr.go
@@ -213,25 +213,6 @@ func (a AttrMask) Empty() bool {
return a == AttrMask{}
}
-// Union returns an AttrMask containing the inclusive disjunction of fields in a and b.
-func (a AttrMask) Union(b AttrMask) AttrMask {
- return AttrMask{
- Type: a.Type || b.Type,
- DeviceID: a.DeviceID || b.DeviceID,
- InodeID: a.InodeID || b.InodeID,
- BlockSize: a.BlockSize || b.BlockSize,
- Size: a.Size || b.Size,
- Usage: a.Usage || b.Usage,
- Perms: a.Perms || b.Perms,
- UID: a.UID || b.UID,
- GID: a.GID || b.GID,
- AccessTime: a.AccessTime || b.AccessTime,
- ModificationTime: a.ModificationTime || b.ModificationTime,
- StatusChangeTime: a.StatusChangeTime || b.StatusChangeTime,
- Links: a.Links || b.Links,
- }
-}
-
// PermMask are file access permissions.
//
// +stateify savable
diff --git a/pkg/sentry/fs/dirent.go b/pkg/sentry/fs/dirent.go
index c1dfa0de7..5587582b5 100644
--- a/pkg/sentry/fs/dirent.go
+++ b/pkg/sentry/fs/dirent.go
@@ -499,7 +499,7 @@ func (d *Dirent) walk(ctx context.Context, root *Dirent, name string, walkMayUnl
//
// We never allow the file system to revalidate mounts, that could cause them
// to unexpectedly drop out before umount.
- if cd.mounted || !cd.Inode.MountSource.Revalidate(ctx, cd.Inode) {
+ if cd.mounted || !cd.Inode.MountSource.Revalidate(ctx, name, d.Inode, cd.Inode) {
// Good to go. This is the fast-path.
return cd, nil
}
diff --git a/pkg/sentry/fs/fsutil/inode_cached.go b/pkg/sentry/fs/fsutil/inode_cached.go
index 0a320e2d8..6777c8bf7 100644
--- a/pkg/sentry/fs/fsutil/inode_cached.go
+++ b/pkg/sentry/fs/fsutil/inode_cached.go
@@ -427,6 +427,47 @@ func (c *CachingInodeOperations) touchStatusChangeTimeLocked(ctx context.Context
c.dirtyAttr.StatusChangeTime = true
}
+// UpdateUnstable updates the cached unstable attributes. Only non-dirty
+// attributes are updated.
+func (c *CachingInodeOperations) UpdateUnstable(attr fs.UnstableAttr) {
+ // All attributes are protected by attrMu.
+ c.attrMu.Lock()
+
+ if !c.dirtyAttr.Usage {
+ c.attr.Usage = attr.Usage
+ }
+ if !c.dirtyAttr.Perms {
+ c.attr.Perms = attr.Perms
+ }
+ if !c.dirtyAttr.UID {
+ c.attr.Owner.UID = attr.Owner.UID
+ }
+ if !c.dirtyAttr.GID {
+ c.attr.Owner.GID = attr.Owner.GID
+ }
+ if !c.dirtyAttr.AccessTime {
+ c.attr.AccessTime = attr.AccessTime
+ }
+ if !c.dirtyAttr.ModificationTime {
+ c.attr.ModificationTime = attr.ModificationTime
+ }
+ if !c.dirtyAttr.StatusChangeTime {
+ c.attr.StatusChangeTime = attr.StatusChangeTime
+ }
+ if !c.dirtyAttr.Links {
+ c.attr.Links = attr.Links
+ }
+
+ // Size requires holding attrMu and dataMu.
+ c.dataMu.Lock()
+ if !c.dirtyAttr.Size {
+ c.attr.Size = attr.Size
+ }
+ c.dataMu.Unlock()
+
+ c.attrMu.Unlock()
+}
+
// Read reads from frames and otherwise directly from the backing file
// into dst starting at offset until dst is full, EOF is reached, or an
// error is encountered.
diff --git a/pkg/sentry/fs/gofer/cache_policy.go b/pkg/sentry/fs/gofer/cache_policy.go
index fa8abf51c..98f43c578 100644
--- a/pkg/sentry/fs/gofer/cache_policy.go
+++ b/pkg/sentry/fs/gofer/cache_policy.go
@@ -17,6 +17,7 @@ package gofer
import (
"fmt"
+ "gvisor.googlesource.com/gvisor/pkg/sentry/context"
"gvisor.googlesource.com/gvisor/pkg/sentry/fs"
)
@@ -108,25 +109,68 @@ func (cp cachePolicy) writeThrough(inode *fs.Inode) bool {
return cp == cacheNone || cp == cacheAllWritethrough
}
-// revalidateDirent indicates that a dirent should be revalidated after a
-// lookup, because the looked up version may be stale.
-func (cp cachePolicy) revalidateDirent() bool {
+// revalidate revalidates the child Inode if the cache policy allows it.
+//
+// Depending on the cache policy, revalidate will walk from the parent to the
+// child inode, and if any unstable attributes have changed, will update the
+// cached attributes on the child inode. If the walk fails, or the returned
+// inode id is different from the one being revalidated, then the entire Dirent
+// must be reloaded.
+func (cp cachePolicy) revalidate(ctx context.Context, name string, parent, child *fs.Inode) bool {
if cp == cacheAll || cp == cacheAllWritethrough {
return false
}
- // TODO: The cacheRemoteRevalidating policy should only
- // return true if the remote file's attributes have changed.
- return true
+ if cp == cacheNone {
+ return true
+ }
+
+ childIops, ok := child.InodeOperations.(*inodeOperations)
+ if !ok {
+ panic(fmt.Sprintf("revalidating inode operations of unknown type %T", child.InodeOperations))
+ }
+ parentIops, ok := parent.InodeOperations.(*inodeOperations)
+ if !ok {
+ panic(fmt.Sprintf("revalidating inode operations with parent of unknown type %T", parent.InodeOperations))
+ }
+
+ // Walk from parent to child again.
+ //
+ // TODO: If we have a directory FD in the parent
+ // inodeOperations, then we can use fstatat(2) to get the inode
+ // attributes instead of making this RPC.
+ qids, _, mask, attr, err := parentIops.fileState.file.walkGetAttr(ctx, []string{name})
+ if err != nil {
+ // Can't look up the name. Trigger reload.
+ return true
+ }
+
+ // If the Path has changed, then we are not looking at the file file.
+ // We must reload.
+ if qids[0].Path != childIops.fileState.key.Inode {
+ return true
+ }
+
+ // If we are not caching unstable attrs, then there is nothing to
+ // update on this inode.
+ if !cp.cacheUAttrs(child) {
+ return false
+ }
+
+ // Update the inode's cached unstable attrs.
+ s := childIops.session()
+ childIops.cachingInodeOps.UpdateUnstable(unstable(ctx, mask, attr, s.mounter, s.client))
+
+ return false
}
-// keepDirent indicates that dirents should be kept pinned in the dirent tree
-// even if there are no application references on the file.
-func (cp cachePolicy) keepDirent(inode *fs.Inode) bool {
+// keep indicates that dirents should be kept pinned in the dirent tree even if
+// there are no application references on the file.
+func (cp cachePolicy) keep(d *fs.Dirent) bool {
if cp == cacheNone {
return false
}
- sattr := inode.StableAttr
+ sattr := d.Inode.StableAttr
// NOTE: Only cache files, directories, and symlinks.
return fs.IsFile(sattr) || fs.IsDir(sattr) || fs.IsSymlink(sattr)
}
diff --git a/pkg/sentry/fs/gofer/gofer_test.go b/pkg/sentry/fs/gofer/gofer_test.go
index 45fdaacfd..c8d7bd773 100644
--- a/pkg/sentry/fs/gofer/gofer_test.go
+++ b/pkg/sentry/fs/gofer/gofer_test.go
@@ -151,41 +151,60 @@ func TestLookup(t *testing.T) {
func TestRevalidation(t *testing.T) {
tests := []struct {
- cachePolicy cachePolicy
- preModificationWantReval bool
- postModificationWantReval bool
+ cachePolicy cachePolicy
+
+ // Whether dirent should be reloaded before any modifications.
+ preModificationWantReload bool
+
+ // Whether dirent should be reloaded after updating an unstable
+ // attribute on the remote fs.
+ postModificationWantReload bool
+
+ // Whether dirent unstable attributes should be updated after
+ // updating an attribute on the remote fs.
+ postModificationWantUpdatedAttrs bool
+
+ // Whether dirent should be reloaded after the remote has
+ // removed the file.
+ postRemovalWantReload bool
}{
{
// Policy cacheNone causes Revalidate to always return
// true.
- cachePolicy: cacheNone,
- preModificationWantReval: true,
- postModificationWantReval: true,
+ cachePolicy: cacheNone,
+ preModificationWantReload: true,
+ postModificationWantReload: true,
+ postModificationWantUpdatedAttrs: true,
+ postRemovalWantReload: true,
},
{
// Policy cacheAll causes Revalidate to always return
// false.
- cachePolicy: cacheAll,
- preModificationWantReval: false,
- postModificationWantReval: false,
+ cachePolicy: cacheAll,
+ preModificationWantReload: false,
+ postModificationWantReload: false,
+ postModificationWantUpdatedAttrs: false,
+ postRemovalWantReload: false,
},
{
// Policy cacheAllWritethrough causes Revalidate to
// always return false.
- cachePolicy: cacheAllWritethrough,
- preModificationWantReval: false,
- postModificationWantReval: false,
+ cachePolicy: cacheAllWritethrough,
+ preModificationWantReload: false,
+ postModificationWantReload: false,
+ postModificationWantUpdatedAttrs: false,
+ postRemovalWantReload: false,
},
{
// Policy cacheRemoteRevalidating causes Revalidate to
- // always return true.
- //
- // TODO: The cacheRemoteRevalidating
- // policy should only return true if the remote file's
- // attributes have changed.
- cachePolicy: cacheRemoteRevalidating,
- preModificationWantReval: true,
- postModificationWantReval: true,
+ // return update cached unstable attrs, and returns
+ // true only when the remote inode itself has been
+ // removed or replaced.
+ cachePolicy: cacheRemoteRevalidating,
+ preModificationWantReload: false,
+ postModificationWantReload: false,
+ postModificationWantUpdatedAttrs: true,
+ postRemovalWantReload: true,
},
}
@@ -227,15 +246,17 @@ func TestRevalidation(t *testing.T) {
if err != nil {
t.Fatalf("Lookup(%q) failed: %v", name, err)
}
- if test.preModificationWantReval && dirent == newDirent {
+ if test.preModificationWantReload && dirent == newDirent {
t.Errorf("Lookup(%q) with cachePolicy=%s got old dirent %v, wanted a new dirent", name, test.cachePolicy, dirent)
}
- if !test.preModificationWantReval && dirent != newDirent {
+ if !test.preModificationWantReload && dirent != newDirent {
t.Errorf("Lookup(%q) with cachePolicy=%s got new dirent %v, wanted old dirent %v", name, test.cachePolicy, newDirent, dirent)
}
// Modify the underlying mocked file's modification time.
- file.GetAttrMock.Attr.MTimeSeconds = uint64(time.Now().Unix())
+ nowSeconds := time.Now().Unix()
+ rootFile.WalkGetAttrMock.Attr.MTimeSeconds = uint64(nowSeconds)
+ file.GetAttrMock.Attr.MTimeSeconds = uint64(nowSeconds)
// Walk again. Depending on the cache policy, we may get a new
// dirent.
@@ -243,12 +264,36 @@ func TestRevalidation(t *testing.T) {
if err != nil {
t.Fatalf("Lookup(%q) failed: %v", name, err)
}
- if test.postModificationWantReval && dirent == newDirent {
+ if test.postModificationWantReload && dirent == newDirent {
t.Errorf("Lookup(%q) with cachePolicy=%s got old dirent %v, wanted a new dirent", name, test.cachePolicy, dirent)
}
- if !test.postModificationWantReval && dirent != newDirent {
+ if !test.postModificationWantReload && dirent != newDirent {
t.Errorf("Lookup(%q) with cachePolicy=%s got new dirent %v, wanted old dirent %v", name, test.cachePolicy, newDirent, dirent)
}
+ uattrs, err := newDirent.Inode.UnstableAttr(ctx)
+ if err != nil {
+ t.Fatalf("Error getting unstable attrs: %v", err)
+ }
+ gotModTimeSeconds := uattrs.ModificationTime.Seconds()
+ if test.postModificationWantUpdatedAttrs && gotModTimeSeconds != nowSeconds {
+ t.Fatalf("Lookup(%q) with cachePolicy=%s got new modification time %v, wanted %v", name, test.cachePolicy, gotModTimeSeconds, nowSeconds)
+ }
+
+ // Make WalkGetAttr return ENOENT. This simulates
+ // removing the file from the remote fs.
+ rootFile.WalkGetAttrMock = p9test.WalkGetAttrMock{
+ Err: syscall.ENOENT,
+ }
+
+ // Walk again. Depending on the cache policy, we may
+ // get ENOENT.
+ newDirent, err = rootDir.Walk(ctx, rootDir, name)
+ if test.postRemovalWantReload && err == nil {
+ t.Errorf("Lookup(%q) with cachePolicy=%s got nil error, wanted ENOENT", name, test.cachePolicy)
+ }
+ if !test.postRemovalWantReload && (err != nil || dirent != newDirent) {
+ t.Errorf("Lookup(%q) with cachePolicy=%s got new dirent %v and error %v, wanted old dirent %v and nil error", name, test.cachePolicy, newDirent, err, dirent)
+ }
})
}
}
diff --git a/pkg/sentry/fs/gofer/session.go b/pkg/sentry/fs/gofer/session.go
index eeb9087e9..49d27ee88 100644
--- a/pkg/sentry/fs/gofer/session.go
+++ b/pkg/sentry/fs/gofer/session.go
@@ -146,13 +146,13 @@ func (s *session) Destroy() {
}
// Revalidate implements MountSource.Revalidate.
-func (s *session) Revalidate(ctx context.Context, i *fs.Inode) bool {
- return s.cachePolicy.revalidateDirent()
+func (s *session) Revalidate(ctx context.Context, name string, parent, child *fs.Inode) bool {
+ return s.cachePolicy.revalidate(ctx, name, parent, child)
}
// Keep implements MountSource.Keep.
func (s *session) Keep(d *fs.Dirent) bool {
- return s.cachePolicy.keepDirent(d.Inode)
+ return s.cachePolicy.keep(d)
}
// ResetInodeMappings implements fs.MountSourceOperations.ResetInodeMappings.
diff --git a/pkg/sentry/fs/mock.go b/pkg/sentry/fs/mock.go
index 89a0103ba..846b6e8bb 100644
--- a/pkg/sentry/fs/mock.go
+++ b/pkg/sentry/fs/mock.go
@@ -68,7 +68,7 @@ func NewMockMountSource(cache *DirentCache) *MountSource {
}
// Revalidate implements fs.MountSourceOperations.Revalidate.
-func (n *MockMountSourceOps) Revalidate(context.Context, *Inode) bool {
+func (n *MockMountSourceOps) Revalidate(context.Context, string, *Inode, *Inode) bool {
return n.revalidate
}
diff --git a/pkg/sentry/fs/mount.go b/pkg/sentry/fs/mount.go
index 455f5b35c..8345876fc 100644
--- a/pkg/sentry/fs/mount.go
+++ b/pkg/sentry/fs/mount.go
@@ -27,10 +27,13 @@ import (
// DirentOperations provide file systems greater control over how long a Dirent stays pinned
// in core. Implementations must not take Dirent.mu.
type DirentOperations interface {
- // Revalidate returns true if the Inode is stale and its
- // InodeOperations needs to be reloaded. Revalidate will never be
- // called on a Inode that is mounted.
- Revalidate(ctx context.Context, inode *Inode) bool
+ // Revalidate is called during lookup each time we encounter a Dirent
+ // in the cache. Implementations may update stale properties of the
+ // child Inode. If Revalidate returns true, then the entire Inode will
+ // be reloaded.
+ //
+ // Revalidate will never be called on a Inode that is mounted.
+ Revalidate(ctx context.Context, name string, parent, child *Inode) bool
// Keep returns true if the Dirent should be kept in memory for as long
// as possible beyond any active references.
@@ -281,7 +284,7 @@ type SimpleMountSourceOperations struct {
}
// Revalidate implements MountSourceOperations.Revalidate.
-func (smo *SimpleMountSourceOperations) Revalidate(context.Context, *Inode) bool {
+func (smo *SimpleMountSourceOperations) Revalidate(context.Context, string, *Inode, *Inode) bool {
return smo.revalidate
}
diff --git a/pkg/sentry/fs/mount_overlay.go b/pkg/sentry/fs/mount_overlay.go
index 9fa87c10f..dbc608c7e 100644
--- a/pkg/sentry/fs/mount_overlay.go
+++ b/pkg/sentry/fs/mount_overlay.go
@@ -41,23 +41,29 @@ func newOverlayMountSource(upper, lower *MountSource, flags MountSourceFlags) *M
// delegating to the upper filesystem's Revalidate method. We cannot reload
// files from the lower filesystem, so we panic if the lower filesystem's
// Revalidate method returns true.
-func (o *overlayMountSourceOperations) Revalidate(ctx context.Context, inode *Inode) bool {
- if inode.overlay == nil {
+func (o *overlayMountSourceOperations) Revalidate(ctx context.Context, name string, parent, child *Inode) bool {
+ if child.overlay == nil {
panic("overlay cannot revalidate inode that is not an overlay")
}
- // Should we bother checking this, or just ignore?
- if inode.overlay.lower != nil && o.lower.Revalidate(ctx, inode.overlay.lower) {
+ // Revalidate is never called on a mount point, so parent and child
+ // must be from the same mount, and thus must both be overlay inodes.
+ if parent.overlay == nil {
+ panic("trying to revalidate an overlay inode but the parent is not an overlay")
+ }
+
+ // We can't revalidate from the lower filesystem.
+ if child.overlay.lower != nil && o.lower.Revalidate(ctx, name, parent.overlay.lower, child.overlay.lower) {
panic("an overlay cannot revalidate file objects from the lower fs")
}
- if inode.overlay.upper == nil {
- // Nothing to revalidate.
+ // Do we have anything to revalidate?
+ if child.overlay.upper == nil {
return false
}
// Does the upper require revalidation?
- return o.upper.Revalidate(ctx, inode.overlay.upper)
+ return o.upper.Revalidate(ctx, name, parent.overlay.upper, child.overlay.upper)
}
// Keep implements MountSourceOperations by delegating to the upper
diff --git a/pkg/sentry/fs/tty/fs.go b/pkg/sentry/fs/tty/fs.go
index fe7da05b5..d9f8f02f3 100644
--- a/pkg/sentry/fs/tty/fs.go
+++ b/pkg/sentry/fs/tty/fs.go
@@ -82,7 +82,7 @@ type superOperations struct{}
// Slave entries are dropped from dir when their master is closed, so an
// existing slave Dirent in the tree is not sufficient to guarantee that it
// still exists on the filesystem.
-func (superOperations) Revalidate(context.Context, *fs.Inode) bool {
+func (superOperations) Revalidate(context.Context, string, *fs.Inode, *fs.Inode) bool {
return true
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-04 12:56:37 +0000