No matches for search in external storage when external storage is not available for user but shared for user

[pmarini-nc]

A user that:

1. is not in the "Available For" of the external storage
2. receives a full share of the external storage

can explore and open files but not search them.

Steps to reproduce

1. Install Nextcloud 21.0.3
2. Create a local folder with owner www-data

sudo mkdir /ext-storage
sudo chown www-data.www-data

3. In Nextcloud, enable External Storage app.
4. Create External Storage:

Folder Name: ext-storage
External Storage: local
Authentication: none
Configuration: /ext-storage
Available for: admin(group)
Options: Enable Preview, Enable Share

5. With admin, create user user1
6. With admin, share the folder ext-storage with user1
7. With admin, move all the default files (Nextcloud intro.mp3, ...) into ext-storage
8. With user1, search for "intro" => matches "Nextcloud intro.mp3"
9. Logout admin
10. With user1, remove all the default files, leave only ext-storage
11. With user1, search for "intro" => No results

Expected behaviour

At step 11, user1 should find a match as in step 8

Actual behaviour

At step 11, user1 doesn't find a match

Server configuration

See the system report
attached

[xadhoom76]

We have tested the problem seems to be after 20.08 (that is the last working correctly). We tested external storage webdav,local,smb.

[PVince81]

okay, got it reproduced.

at first I was sharing "/ext-storage/subdir" instead of "/ext-storage" directly.
sharing the mount point is a bit special internally which could explain why it's not working.

if it was working before I should be able to bisect to find out what change introduced the problem

[PVince81]

here we go 5d08beb

introduced through #26134 which is intended to optimize the speed of the search

@icewind1991 mind having a look ?

[PVince81]

PR here: #28175