Add self/primary symlink on /mnt/pass_through

We bind mount /mnt/user/<userid> onto /storage for normal apps and
/mnt/pass_through/<userid> for special apps like the FUSE daemon or
the old android.process.media hosting the DownloadManager. This bind
mount allows app have /storage/self/primary which is what /sdcard
symlinks to.

Before this change, we were not creating the self/primary symlink on
/mnt/pass_through/<userid> so trying to access /sdcard from the
DownloadManager would fail.

Bug: 135341433
Test: atest android.app.cts.DownloadManagerTest#testAddCompletedDownload_invalidPaths
Change-Id: I660139be3d850e6e9ea4705f86ef2b5872ddca16
1 file changed