linux – WSL (Ubuntu 20.04) – unstable permissions

I’m new to WSL and trying to use rsync for snapshot backups. Everything seems to be working as intended… except that rsync refuses to copy some files, citing a permission error with send_files.

So I tried to change globally the permissions for all files and folders, to make them all readable. Again, failure with certain files. I then went to look at these specific directories and found this, for example:

m17awl@M17A:/mnt/d/My Documents/software projects/operative/LuceneIndexer_3/3.0.12/lib$ ls -lsa
total 48332
   0 drwxrwxrwx 1 m17awl m17awl     512 Jan 21  2020 .
   0 drwxrwxrwx 1 m17awl m17awl     512 Jan 21  2020 ..
  52 ---------- 1 m17awl m17awl   51141 Jan 23  2020 LuceneIndexer_3-3.0.12.jar
   4 ---------- 1 m17awl m17awl    3482 Jan 23  2020 animal-sniffer-annotations-1.14.jar
2020 ---------- 1 m17awl m17awl 2067867 Jan 23  2020 ant-1.9.13.jar

hmmm… no permissions. OK, I try to change these, seemingly successfully:

m17awl@M17A:/mnt/d/My Documents/software projects/operative/LuceneIndexer_3/3.0.12/lib$ sudo chmod -R +r .
(sudo) password for m17awl:
m17awl@M17A:/mnt/d/My Documents/software projects/operative/LuceneIndexer_3/3.0.12/lib$ ls -lsa
total 48332
   0 drwxrwxrwx 1 m17awl m17awl     512 Jan 21  2020 .
   0 drwxrwxrwx 1 m17awl m17awl     512 Jan 21  2020 ..
  52 -r-xr-xr-x 1 m17awl m17awl   51141 Jan 23  2020 LuceneIndexer_3-3.0.12.jar
   4 -r-xr-xr-x 1 m17awl m17awl    3482 Jan 23  2020 animal-sniffer-annotations-1.14.jar
2020 -r-xr-xr-x 1 m17awl m17awl 2067867 Jan 23  2020 ant-1.9.13.jar

I run rsync again… and get the same permission failures, including with these files in this particular directory:

m17awl@M17A:/mnt/d/My Documents$ rsync --progress --update --recursive --times --link-dest=/mnt/f/Backups/rsync/My Documents/snapshot2021-02-21T203900/ /mnt/d/My Documents/ /mnt/f/Backups/rsync/My Documents/snapshot2021-02-22T071700/
sending incremental file list
...
rsync: send_files failed to open "/mnt/d/My Documents/software projects/operative/LuceneIndexer_3/3.0.12/bin/LuceneIndexer_3": Permission denied (13)
rsync: send_files failed to open "/mnt/d/My Documents/software projects/operative/LuceneIndexer_3/3.0.12/lib/LuceneIndexer_3-3.0.12.jar": Permission denied (13)
rsync: send_files failed to open "/mnt/d/My Documents/software projects/operative/LuceneIndexer_3/3.0.12/lib/animal-sniffer-annotations-1.14.jar": Permission denied (13)
rsync: send_files failed to open "/mnt/d/My Documents/software projects/operative/LuceneIndexer_3/3.0.12/lib/ant-1.9.13.jar": Permission denied (13)

… and when I go back and look at the directory again I find the permissions on these files have been “destroyed” (i.e. again set to ----------).

Anyone got any idea what’s going here… any solutions?