Merge release-20200422.0-297-gd846077 (automated)

2 files changed, 7 insertions, 5 deletions

diff --git a/pkg/sentry/fs/gofer/fs.go b/pkg/sentry/fs/gofer/fs.go
index 9d41fcbdb..8ae2d78d7 100644
--- a/pkg/sentry/fs/gofer/fs.go
+++ b/pkg/sentry/fs/gofer/fs.go
@@ -60,8 +60,7 @@ const (
 	limitHostFDTranslationKey = "limit_host_fd_translation"
 
 	// overlayfsStaleRead if present closes cached readonly file after the first
-	// write. This is done to workaround a limitation of overlayfs in kernels
-	// before 4.19 where open FDs are not updated after the file is copied up.
+	// write. This is done to workaround a limitation of Linux overlayfs.
 	overlayfsStaleRead = "overlayfs_stale_read"
 )
 
diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go
index 1da8d5d82..353e2cf5b 100755
--- a/pkg/sentry/fsimpl/gofer/gofer.go
+++ b/pkg/sentry/fsimpl/gofer/gofer.go
@@ -143,9 +143,12 @@ type filesystemOptions struct {
 
 	// If overlayfsStaleRead is true, O_RDONLY host FDs provided by the remote
 	// filesystem may not be coherent with writable host FDs opened later, so
-	// mappings of the former must be replaced by mappings of the latter. This
-	// is usually only the case when the remote filesystem is an overlayfs
-	// mount on Linux < 4.19.
+	// all uses of the former must be replaced by uses of the latter. This is
+	// usually only the case when the remote filesystem is a Linux overlayfs
+	// mount. (Prior to Linux 4.18, patch series centered on commit
+	// d1d04ef8572b "ovl: stack file ops", both I/O and memory mappings were
+	// incoherent between pre-copy-up and post-copy-up FDs; after that patch
+	// series, only memory mappings are incoherent.)
 	overlayfsStaleRead bool
 
 	// If regularFilesUseSpecialFileFD is true, application FDs representing