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gofer: Support restore of deleted directories whose original path is occupied. #11843

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gofer: Support restore of deleted directories whose original path is occupied. #11843

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23 changes: 16 additions & 7 deletions pkg/sentry/fsimpl/gofer/save_restore.go
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Original file line number Diff line number Diff line change
Expand Up @@ -327,7 +327,7 @@ func (fs *filesystem) CompleteRestore(ctx context.Context, opts vfs.CompleteRest
}

// Restore deleted files which are still accessible via open application FDs.
dirsToDelete := make(map[*dentry]struct{})
dirsToDelete := make(map[*dentry]string)
for d := range fs.savedDeletedOpenDentries {
if err := d.restoreDeleted(ctx, &opts, dirsToDelete); err != nil {
return err
Expand All @@ -344,7 +344,10 @@ func (fs *filesystem) CompleteRestore(ctx context.Context, opts vfs.CompleteRest
delete(leafDirectories, d.parent.Load())
}
for leafD := range leafDirectories {
if err := leafD.parent.Load().unlink(ctx, leafD.name, linux.AT_REMOVEDIR); err != nil {
// Note that we use the name specified in dirsToDelete map, which is the
// name used to create the temporary directory. This name may differ from
// leafD.name if another non-deleted directory already exists there.
if err := leafD.parent.Load().unlink(ctx, dirsToDelete[leafD], linux.AT_REMOVEDIR); err != nil {
return fmt.Errorf("failed to clean up recreated deleted directory %q: %v", genericDebugPathname(fs, leafD), err)
}
delete(dirsToDelete, leafD)
Expand Down Expand Up @@ -384,7 +387,7 @@ func (d *dentry) restoreDescendantsRecursive(ctx context.Context, opts *vfs.Comp
// Preconditions:
// - d.isRegularFile() || d.isDir()
// - d.savedDeletedData != nil iff d.isRegularFile()
func (d *dentry) restoreDeleted(ctx context.Context, opts *vfs.CompleteRestoreOptions, dirsToDelete map[*dentry]struct{}) error {
func (d *dentry) restoreDeleted(ctx context.Context, opts *vfs.CompleteRestoreOptions, dirsToDelete map[*dentry]string) error {
parent := d.parent.Load()
if _, ok := d.fs.savedDeletedOpenDentries[parent]; ok {
// Recursively restore the parent first if the parent is also deleted.
Expand All @@ -402,23 +405,29 @@ func (d *dentry) restoreDeleted(ctx context.Context, opts *vfs.CompleteRestoreOp
}
}

func (d *dentry) restoreDeletedDirectory(ctx context.Context, opts *vfs.CompleteRestoreOptions, dirsToDelete map[*dentry]struct{}) error {
func (d *dentry) restoreDeletedDirectory(ctx context.Context, opts *vfs.CompleteRestoreOptions, dirsToDelete map[*dentry]string) error {
// Recreate the directory on the host filesystem. This will be deleted later.
parent := d.parent.Load()
_, err := parent.mkdir(ctx, d.name, linux.FileMode(d.mode.Load()), auth.KUID(d.uid.Load()), auth.KGID(d.gid.Load()), false /* createDentry */)
name := d.name
_, err := parent.mkdir(ctx, name, linux.FileMode(d.mode.Load()), auth.KUID(d.uid.Load()), auth.KGID(d.gid.Load()), false /* createDentry */)
if linuxerr.Equals(linuxerr.EEXIST, err) {
name = fmt.Sprintf("%s.tmp-gvisor-restore", name)
log.Warningf("Deleted directory %q was replaced with a new directory at the same path, using new name %q", genericDebugPathname(d.fs, d), name)
_, err = parent.mkdir(ctx, name, linux.FileMode(d.mode.Load()), auth.KUID(d.uid.Load()), auth.KGID(d.gid.Load()), false /* createDentry */)
}
if err != nil {
return fmt.Errorf("failed to re-create deleted directory %q: %w", genericDebugPathname(d.fs, d), err)
}
// Restore the directory.
if err := d.restoreFile(ctx, opts); err != nil {
if err := parent.unlink(ctx, d.name, linux.AT_REMOVEDIR); err != nil {
if err := parent.unlink(ctx, name, linux.AT_REMOVEDIR); err != nil {
log.Warningf("failed to clean up recreated deleted directory %q: %v", genericDebugPathname(d.fs, d), err)
}
return fmt.Errorf("failed to restore deleted directory: %w", err)
}
// We will delete the directory later. We need to keep it around in case any
// of its children need to be restored after this.
dirsToDelete[d] = struct{}{}
dirsToDelete[d] = name
delete(d.fs.savedDeletedOpenDentries, d)
return nil
}
Expand Down