From 2bc398bfd8fbe38776a512329bd0c40c9c7a5cdf Mon Sep 17 00:00:00 2001
From: Jamie Liu <jamieliu@google.com>
Date: Wed, 17 Jul 2019 15:48:33 -0700
Subject: Separate O_DSYNC and O_SYNC.

PiperOrigin-RevId: 258657913
---
 pkg/abi/linux/file.go              | 3 ++-
 pkg/sentry/fs/flags.go             | 9 ++++++++-
 pkg/sentry/syscalls/linux/flags.go | 1 +
 3 files changed, 11 insertions(+), 2 deletions(-)

(limited to 'pkg')

diff --git a/pkg/abi/linux/file.go b/pkg/abi/linux/file.go
index f78ffaa82..285338e47 100644
--- a/pkg/abi/linux/file.go
+++ b/pkg/abi/linux/file.go
@@ -34,13 +34,14 @@ const (
 	O_TRUNC     = 00001000
 	O_APPEND    = 00002000
 	O_NONBLOCK  = 00004000
+	O_DSYNC     = 00010000
 	O_ASYNC     = 00020000
 	O_DIRECT    = 00040000
 	O_LARGEFILE = 00100000
 	O_DIRECTORY = 00200000
 	O_NOFOLLOW  = 00400000
 	O_CLOEXEC   = 02000000
-	O_SYNC      = 04010000
+	O_SYNC      = 04000000
 	O_PATH      = 010000000
 )
 
diff --git a/pkg/sentry/fs/flags.go b/pkg/sentry/fs/flags.go
index 1278f9c78..0fab876a9 100644
--- a/pkg/sentry/fs/flags.go
+++ b/pkg/sentry/fs/flags.go
@@ -28,7 +28,11 @@ type FileFlags struct {
 	// NonBlocking indicates that I/O should not block.
 	NonBlocking bool
 
-	// Sync indicates that any writes should be synchronous.
+	// DSync indicates that each write will flush data and metadata required to
+	// read the file's contents.
+	DSync bool
+
+	// Sync indicates that each write will flush data and all file metadata.
 	Sync bool
 
 	// Append indicates this file is append only.
@@ -96,6 +100,9 @@ func (f FileFlags) ToLinux() (mask uint) {
 	if f.NonBlocking {
 		mask |= linux.O_NONBLOCK
 	}
+	if f.DSync {
+		mask |= linux.O_DSYNC
+	}
 	if f.Sync {
 		mask |= linux.O_SYNC
 	}
diff --git a/pkg/sentry/syscalls/linux/flags.go b/pkg/sentry/syscalls/linux/flags.go
index 0c1b5ec27..444f2b004 100644
--- a/pkg/sentry/syscalls/linux/flags.go
+++ b/pkg/sentry/syscalls/linux/flags.go
@@ -41,6 +41,7 @@ func flagsToPermissions(mask uint) (p fs.PermMask) {
 func linuxToFlags(mask uint) fs.FileFlags {
 	return fs.FileFlags{
 		Direct:      mask&linux.O_DIRECT != 0,
+		DSync:       mask&(linux.O_DSYNC|linux.O_SYNC) != 0,
 		Sync:        mask&linux.O_SYNC != 0,
 		NonBlocking: mask&linux.O_NONBLOCK != 0,
 		Read:        (mask & linux.O_ACCMODE) != linux.O_WRONLY,
-- 
cgit v1.2.3


From 6f7e2bb388cb29a355dece8921671c0085f53ea9 Mon Sep 17 00:00:00 2001
From: Michael Pratt <mpratt@google.com>
Date: Wed, 17 Jul 2019 16:10:44 -0700
Subject: Take copyMu in Revalidate

copyMu is required to read child.overlay.upper.

PiperOrigin-RevId: 258662209
---
 pkg/sentry/fs/mount_overlay.go | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

(limited to 'pkg')

diff --git a/pkg/sentry/fs/mount_overlay.go b/pkg/sentry/fs/mount_overlay.go
index 4fcdd6c01..299712cd7 100644
--- a/pkg/sentry/fs/mount_overlay.go
+++ b/pkg/sentry/fs/mount_overlay.go
@@ -66,13 +66,17 @@ func (o *overlayMountSourceOperations) Revalidate(ctx context.Context, name stri
 		panic("an overlay cannot revalidate file objects from the lower fs")
 	}
 
-	// Do we have anything to revalidate?
-	if child.overlay.upper == nil {
-		return false
+	var revalidate bool
+	child.overlay.copyMu.RLock()
+	if child.overlay.upper != nil {
+		// Does the upper require revalidation?
+		revalidate = o.upper.Revalidate(ctx, name, parent.overlay.upper, child.overlay.upper)
+	} else {
+		// Nothing to revalidate.
+		revalidate = false
 	}
-
-	// Does the upper require revalidation?
-	return o.upper.Revalidate(ctx, name, parent.overlay.upper, child.overlay.upper)
+	child.overlay.copyMu.RUnlock()
+	return revalidate
 }
 
 // Keep implements MountSourceOperations by delegating to the upper
-- 
cgit v1.2.3