Migrate from using io.ReadSeeker to io.ReaderAt.

This provides the following benefits:
- We can now use pkg/fd package which does not take ownership
  of the file descriptor. So it does not close the fd when garbage collected.
  This reduces scope of errors from unexpected garbage collection of io.File.
- It enforces the offset parameter in every read call.
  It does not affect the fd offset nor is it affected by it. Hence reducing
  scope of error of using stale offsets when reading.
- We do not need to serialize the usage of any global file descriptor anymore.
  So this drops the mutual exclusion req hence reducing complexity and
  congestion.

PiperOrigin-RevId: 260635174

1 files changed, 1 insertions, 3 deletions

diff --git a/pkg/sentry/fs/ext/symlink.go b/pkg/sentry/fs/ext/symlink.go
index 0ed67c0e4..6a55c1a7b 100644
--- a/pkg/sentry/fs/ext/symlink.go
+++ b/pkg/sentry/fs/ext/symlink.go
@@ -28,9 +28,7 @@ type symlink struct {
 
 // newSymlink is the symlink constructor. It reads out the symlink target from
 // the inode (however it might have been stored).
-//
-// Preconditions: Must hold the mutex of the filesystem containing dev.
-func newSymlink(dev io.ReadSeeker, blkSize uint64, inode inode) (*symlink, error) {
+func newSymlink(dev io.ReaderAt, blkSize uint64, inode inode) (*symlink, error) {
 	var file *symlink
 	var link []byte