7 files changed, 26 insertions, 18 deletions
diff --git a/pkg/sentry/fsimpl/ext/BUILD b/pkg/sentry/fsimpl/ext/BUILD
index ef24f8159..abc610ef3 100644
--- a/pkg/sentry/fsimpl/ext/BUILD
+++ b/pkg/sentry/fsimpl/ext/BUILD
@@ -96,7 +96,7 @@ go_test(
         "//pkg/syserror",
         "//pkg/test/testutil",
         "//pkg/usermem",
-        "@com_github_google_go-cmp//cmp:go_default_library",
-        "@com_github_google_go-cmp//cmp/cmpopts:go_default_library",
+        "@com_github_google_go_cmp//cmp:go_default_library",
+        "@com_github_google_go_cmp//cmp/cmpopts:go_default_library",
     ],
 )
diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go
index 2b83094cd..b74d489a0 100644
--- a/pkg/sentry/fsimpl/gofer/gofer.go
+++ b/pkg/sentry/fsimpl/gofer/gofer.go
@@ -602,8 +602,14 @@ type dentry struct {
 	// returned by the server. dirents is protected by dirMu.
 	dirents []vfs.Dirent
 
-	// Cached metadata; protected by metadataMu and accessed using atomic
-	// memory operations unless otherwise specified.
+	// Cached metadata; protected by metadataMu.
+	// To access:
+	//   - In situations where consistency is not required (like stat), these
+	//     can be accessed using atomic operations only (without locking).
+	//   - Lock metadataMu and can access without atomic operations.
+	// To mutate:
+	//   - Lock metadataMu and use atomic operations to update because we might
+	//     have atomic readers that don't hold the lock.
 	metadataMu sync.Mutex
 	ino        inodeNumber // immutable
 	mode       uint32      // type is immutable, perms are mutable
@@ -616,7 +622,7 @@ type dentry struct {
 	ctime int64
 	btime int64
 	// File size, protected by both metadataMu and dataMu (i.e. both must be
-	// locked to mutate it).
+	// locked to mutate it; locking either is sufficient to access it).
 	size uint64
 
 	// nlink counts the number of hard links to this dentry. It's updated and
@@ -904,14 +910,14 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *lin
 
 		// Prepare for truncate.
 		if stat.Mask&linux.STATX_SIZE != 0 {
-			switch d.mode & linux.S_IFMT {
-			case linux.S_IFREG:
+			switch mode.FileType() {
+			case linux.ModeRegular:
 				if !setLocalMtime {
 					// Truncate updates mtime.
 					setLocalMtime = true
 					stat.Mtime.Nsec = linux.UTIME_NOW
 				}
-			case linux.S_IFDIR:
+			case linux.ModeDirectory:
 				return syserror.EISDIR
 			default:
 				return syserror.EINVAL
@@ -994,7 +1000,7 @@ func (d *dentry) setStat(ctx context.Context, creds *auth.Credentials, stat *lin
 func (d *dentry) updateFileSizeLocked(newSize uint64) {
 	d.dataMu.Lock()
 	oldSize := d.size
-	d.size = newSize
+	atomic.StoreUint64(&d.size, newSize)
 	// d.dataMu must be unlocked to lock d.mapsMu and invalidate mappings
 	// below. This allows concurrent calls to Read/Translate/etc. These
 	// functions synchronize with truncation by refusing to use cache
@@ -1340,8 +1346,8 @@ func (d *dentry) removexattr(ctx context.Context, creds *auth.Credentials, name
 // Extended attributes in the user.* namespace are only supported for regular
 // files and directories.
 func (d *dentry) userXattrSupported() bool {
-	filetype := linux.S_IFMT & atomic.LoadUint32(&d.mode)
-	return filetype == linux.S_IFREG || filetype == linux.S_IFDIR
+	filetype := linux.FileMode(atomic.LoadUint32(&d.mode)).FileType()
+	return filetype == linux.ModeRegular || filetype == linux.ModeDirectory
 }
 
 // Preconditions: !d.isSynthetic(). d.isRegularFile() || d.isDir().
diff --git a/pkg/sentry/fsimpl/gofer/regular_file.go b/pkg/sentry/fsimpl/gofer/regular_file.go
index a2f02d9c7..f10350c97 100644
--- a/pkg/sentry/fsimpl/gofer/regular_file.go
+++ b/pkg/sentry/fsimpl/gofer/regular_file.go
@@ -89,7 +89,9 @@ func (fd *regularFileFD) Allocate(ctx context.Context, mode, offset, length uint
 	if err != nil {
 		return err
 	}
-	d.size = size
+	d.dataMu.Lock()
+	atomic.StoreUint64(&d.size, size)
+	d.dataMu.Unlock()
 	if !d.cachedMetadataAuthoritative() {
 		d.touchCMtimeLocked()
 	}
diff --git a/pkg/sentry/fsimpl/gofer/special_file.go b/pkg/sentry/fsimpl/gofer/special_file.go
index c1e6b13e5..a7b53b2d2 100644
--- a/pkg/sentry/fsimpl/gofer/special_file.go
+++ b/pkg/sentry/fsimpl/gofer/special_file.go
@@ -28,9 +28,9 @@ import (
 )
 
 // specialFileFD implements vfs.FileDescriptionImpl for pipes, sockets, device
-// special files, and (when filesystemOptions.specialRegularFiles is in effect)
-// regular files. specialFileFD differs from regularFileFD by using per-FD
-// handles instead of shared per-dentry handles, and never buffering I/O.
+// special files, and (when filesystemOptions.regularFilesUseSpecialFileFD is
+// in effect) regular files. specialFileFD differs from regularFileFD by using
+// per-FD handles instead of shared per-dentry handles, and never buffering I/O.
 type specialFileFD struct {
 	fileDescription
 
diff --git a/pkg/sentry/fsimpl/kernfs/BUILD b/pkg/sentry/fsimpl/kernfs/BUILD
index 179df6c1e..3835557fe 100644
--- a/pkg/sentry/fsimpl/kernfs/BUILD
+++ b/pkg/sentry/fsimpl/kernfs/BUILD
@@ -70,6 +70,6 @@ go_test(
         "//pkg/sentry/vfs",
         "//pkg/syserror",
         "//pkg/usermem",
-        "@com_github_google_go-cmp//cmp:go_default_library",
+        "@com_github_google_go_cmp//cmp:go_default_library",
     ],
 )
diff --git a/pkg/sentry/fsimpl/sys/BUILD b/pkg/sentry/fsimpl/sys/BUILD
index a741e2bb6..1b548ccd4 100644
--- a/pkg/sentry/fsimpl/sys/BUILD
+++ b/pkg/sentry/fsimpl/sys/BUILD
@@ -29,6 +29,6 @@ go_test(
         "//pkg/sentry/kernel",
         "//pkg/sentry/kernel/auth",
         "//pkg/sentry/vfs",
-        "@com_github_google_go-cmp//cmp:go_default_library",
+        "@com_github_google_go_cmp//cmp:go_default_library",
     ],
 )
diff --git a/pkg/sentry/fsimpl/testutil/BUILD b/pkg/sentry/fsimpl/testutil/BUILD
index 0e4053a46..400a97996 100644
--- a/pkg/sentry/fsimpl/testutil/BUILD
+++ b/pkg/sentry/fsimpl/testutil/BUILD
@@ -32,6 +32,6 @@ go_library(
         "//pkg/sentry/vfs",
         "//pkg/sync",
         "//pkg/usermem",
-        "@com_github_google_go-cmp//cmp:go_default_library",
+        "@com_github_google_go_cmp//cmp:go_default_library",
     ],
 )