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// Copyright 2018 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 fs_test
import (
"bytes"
"crypto/rand"
"fmt"
"io"
"sync"
"testing"
"gvisor.dev/gvisor/pkg/sentry/fs"
_ "gvisor.dev/gvisor/pkg/sentry/fs/tmpfs"
"gvisor.dev/gvisor/pkg/sentry/kernel/contexttest"
"gvisor.dev/gvisor/pkg/sentry/usermem"
)
const (
// origFileSize is the original file size. This many bytes should be
// copied up before the test file is modified.
origFileSize = 4096
// truncatedFileSize is the size to truncate all test files.
truncateFileSize = 10
)
// TestConcurrentCopyUp is a copy up stress test for an overlay.
//
// It creates a 64-level deep directory tree in the lower filesystem and
// populates the last subdirectory with 64 files containing random content:
//
// /lower
// /sudir0/.../subdir63/
// /file0
// ...
// /file63
//
// The files are truncated concurrently by 4 goroutines per file.
// These goroutines contend with copying up all parent 64 subdirectories
// as well as the final file content.
//
// At the end of the test, we assert that the files respect the new truncated
// size and contain the content we expect.
func TestConcurrentCopyUp(t *testing.T) {
ctx := contexttest.Context(t)
files := makeOverlayTestFiles(t)
var wg sync.WaitGroup
for _, file := range files {
for i := 0; i < 4; i++ {
wg.Add(1)
go func(o *overlayTestFile) {
if err := o.File.Dirent.Inode.Truncate(ctx, o.File.Dirent, truncateFileSize); err != nil {
t.Fatalf("failed to copy up: %v", err)
}
wg.Done()
}(file)
}
}
wg.Wait()
for _, file := range files {
got := make([]byte, origFileSize)
n, err := file.File.Readv(ctx, usermem.BytesIOSequence(got))
if int(n) != truncateFileSize {
t.Fatalf("read %d bytes from file, want %d", n, truncateFileSize)
}
if err != nil && err != io.EOF {
t.Fatalf("read got error %v, want nil", err)
}
if !bytes.Equal(got[:n], file.content[:truncateFileSize]) {
t.Fatalf("file content is %v, want %v", got[:n], file.content[:truncateFileSize])
}
}
}
type overlayTestFile struct {
File *fs.File
name string
content []byte
}
func makeOverlayTestFiles(t *testing.T) []*overlayTestFile {
ctx := contexttest.Context(t)
// Create a lower tmpfs mount.
fsys, _ := fs.FindFilesystem("tmpfs")
lower, err := fsys.Mount(contexttest.Context(t), "", fs.MountSourceFlags{}, "", nil)
if err != nil {
t.Fatalf("failed to mount tmpfs: %v", err)
}
lowerRoot := fs.NewDirent(ctx, lower, "")
// Make a deep set of subdirectories that everyone shares.
next := lowerRoot
for i := 0; i < 64; i++ {
name := fmt.Sprintf("subdir%d", i)
err := next.CreateDirectory(ctx, lowerRoot, name, fs.FilePermsFromMode(0777))
if err != nil {
t.Fatalf("failed to create dir %q: %v", name, err)
}
next, err = next.Walk(ctx, lowerRoot, name)
if err != nil {
t.Fatalf("failed to walk to %q: %v", name, err)
}
}
// Make a bunch of files in the last directory.
var files []*overlayTestFile
for i := 0; i < 64; i++ {
name := fmt.Sprintf("file%d", i)
f, err := next.Create(ctx, next, name, fs.FileFlags{Read: true, Write: true}, fs.FilePermsFromMode(0666))
if err != nil {
t.Fatalf("failed to create file %q: %v", name, err)
}
defer f.DecRef()
relname, _ := f.Dirent.FullName(lowerRoot)
o := &overlayTestFile{
name: relname,
content: make([]byte, origFileSize),
}
if _, err := rand.Read(o.content); err != nil {
t.Fatalf("failed to read from /dev/urandom: %v", err)
}
if _, err := f.Writev(ctx, usermem.BytesIOSequence(o.content)); err != nil {
t.Fatalf("failed to write content to file %q: %v", name, err)
}
files = append(files, o)
}
// Create an empty upper tmpfs mount which we will copy up into.
upper, err := fsys.Mount(ctx, "", fs.MountSourceFlags{}, "", nil)
if err != nil {
t.Fatalf("failed to mount tmpfs: %v", err)
}
// Construct an overlay root.
overlay, err := fs.NewOverlayRoot(ctx, upper, lower, fs.MountSourceFlags{})
if err != nil {
t.Fatalf("failed to construct overlay root: %v", err)
}
// Create a MountNamespace to traverse the file system.
mns, err := fs.NewMountNamespace(ctx, overlay)
if err != nil {
t.Fatalf("failed to construct mount manager: %v", err)
}
// Walk to all of the files in the overlay, open them readable.
for _, f := range files {
maxTraversals := uint(0)
d, err := mns.FindInode(ctx, mns.Root(), mns.Root(), f.name, &maxTraversals)
if err != nil {
t.Fatalf("failed to find %q: %v", f.name, err)
}
defer d.DecRef()
f.File, err = d.Inode.GetFile(ctx, d, fs.FileFlags{Read: true})
if err != nil {
t.Fatalf("failed to open file %q readable: %v", f.name, err)
}
}
return files
}
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