fuse: add benchmarking support for FUSE

This change adds the following:
-  Add support for containerizing syscall tests for FUSE
-  Mount tmpfs in the container so we can run benchmarks against it
-  Run the server in a background process
-  benchmarks for fuse syscall

Co-authored-by: Ridwan Sharif <ridwanmsharif@google.com>

3 files changed, 77 insertions, 0 deletions

diff --git a/pkg/sentry/fs/g3doc/fuse.md b/pkg/sentry/fs/g3doc/fuse.md
index 2ca84dd74..496e339ce 100644
--- a/pkg/sentry/fs/g3doc/fuse.md
+++ b/pkg/sentry/fs/g3doc/fuse.md
@@ -254,6 +254,53 @@ I/O syscalls like `read(2)`, `write(2)` and `mmap(2)`.
 -   `FUSE_BMAP`: Old address space API for block defrag. Probably not needed.
 -   `FUSE_NOTIFY_REPLY`: [TODO: what does this do?]
 
+## Benchmark FUSE
+
+FUSE benchmark makes FUSE syscall inside docker container to make sure required
+environment conditions are met - such as having the right libraries to start a
+FUSE server.
+
+### Setup
+
+To run benchmark:
+
+1. Make sure you have `Docker` installed.
+2. Download all docker images `make load-all-images`.
+3. Config `runsc` docker runtime to have VFS2 and FUSE supported.
+(e.g.  `make configure RUNTIME=runsc ARGS="--vfs2 --fuse ..." ...`)
+
+You should now have a runtime with the following options configured in
+`/etc/docker/daemon.json`
+```
+"runsc": {
+            "path": "path/to/your/runsc",
+            "runtimeArgs": [
+                "--vfs2",
+                "--fuse"
+                ... 
+            ]
+        }
+```
+
+### Running benchmarks
+With above setup, benchmark can be run with following command
+```
+bazel test --test_output=all --cache_test_results=no --test_arg=-test.bench= //path/to:target
+```
+For example: if you want to run stat test
+```
+bazel test --test_output=all --cache_test_results=no --test_arg=-test.bench= //test/fuse:open_benchmark_runsc_ptrace_vfs2_fuse_container
+```
+
+Note:
+- test target need to have `vfs2_fuse_container` to run in container with `vfs2` and `fuse` enabled
+- `test_output` set to `all` to view the result in terminal
+- `--cache_test_results` set to `no` to avoid cached benchmark
+
+### Use your fuse server
+
+To use your own FUSE server, change the `images/basic/fuse/Dockerfile` to compile your FUSE server into the container and name it `server-bin`.
+
 # References
 
 -   [fuse(4) Linux manual page](https://www.man7.org/linux/man-pages/man4/fuse.4.html)
diff --git a/pkg/test/dockerutil/container.go b/pkg/test/dockerutil/container.go
index 64d17f661..727be26b2 100644
--- a/pkg/test/dockerutil/container.go
+++ b/pkg/test/dockerutil/container.go
@@ -136,6 +136,11 @@ func MakeNativeContainer(ctx context.Context, logger testutil.Logger) *Container
 	}
 }
 
+// Runtime returns the runtime of the container.
+func (c *Container) Runtime() string {
+	return c.runtime
+}
+
 // AddProfile adds a profile to this container.
 func (c *Container) AddProfile(p Profile) {
 	c.profiles = append(c.profiles, p)
@@ -541,3 +546,8 @@ func (c *Container) CleanUp(ctx context.Context) {
 	// Forget all mounts.
 	c.mounts = nil
 }
+
+// CopyErr returns the error that happened during copy.
+func (c *Container) CopyErr() error {
+	return c.copyErr
+}
diff --git a/pkg/test/dockerutil/dockerutil.go b/pkg/test/dockerutil/dockerutil.go
index 7027df1a5..a2d7e8c85 100644
--- a/pkg/test/dockerutil/dockerutil.go
+++ b/pkg/test/dockerutil/dockerutil.go
@@ -121,6 +121,26 @@ func UsingVFS2() (bool, error) {
 	return false, nil
 }
 
+// UsingFUSE returns true if the 'runtime' has the fuse flag set.
+func UsingFUSE() (bool, error) {
+	rMap, err := runtimeMap()
+	if err != nil {
+		return false, err
+	}
+
+	list, ok := rMap["runtimeArgs"].([]interface{})
+	if !ok {
+		return false, fmt.Errorf("unexpected format: %v", rMap)
+	}
+
+	for _, element := range list {
+		if element == "--fuse" {
+			return true, nil
+		}
+	}
+	return false, nil
+}
+
 func runtimeMap() (map[string]interface{}, error) {
 	// Read the configuration data; the file must exist.
 	configBytes, err := ioutil.ReadFile(*config)