Improve data directory write checking for NFS mounts

[rcdailey]

If is_writable() fails, fall back to logic that attempts to create a file
and then checks if it exists. If this check fails, an error occurs as it
did before.

Discussion on this solution was found here:
https://help.nextcloud.com/t/write-errors-for-nfs-mount/23328

Fixes #7124

[rcdailey]

I'm very doubtful the developers want this logic to be completely removed. I'd love some feedback from the developers on what the appropriate solution should be. Additional configuration to disable the checks? Replace the checks with something less ambiguous? Let me know.

[rullzer]

After some checking this seems to indeed be bug in the is_writable (or more precisely in the access function called). This might not work correctly on NFS mounts.

@rcdailey can I ask you to modify this PR. And instead of removing the faling tests. if the test fail try to write a file to the data directory (generate a long unqiue fiename, try to write it?).

Then I'm fine with getting this in.

[rcdailey]

@rullzer Could we please get this into stable15? I'm trying to keep the scope of change minimal so that it can be applied as a hotfix for current production release. I personally will not upgrade to v16 until it releases, and the next hotfix for 15 will come out faster. Not sure what your process is but can this be done?

Also, I run Nextcloud in a docker container. Using VS Code to debug PHP from Windows to a Docker Container seems sophisticated, so I'm not sure the best way to test this. Advice is appreciated. I am not normally a PHP developer so this technology is new to me.

[rcdailey]

So I just replaced the PHP code in my config directory on my live instance, booted, and it worked. For a moment when I refreshed the page, I saw the text of the filename in the browser view, but after I did a 2nd refresh it went back to Nextcloud. So I'm not sure what that was about.

[rullzer]

It gets into master first and then it gets backported.

[rcdailey]

Ok I will let you test on master. I don't know how to do that without updrading my server to v16 which I don't want to do.

[rcdailey]

@rullzer I've worked through a lot of the issues I had, although I can't consistently get Nextcloud to execute the checkServer() code. Seems to happen non-deterministically. Advice on how to properly reproduce the server check logic would be very helpful.

In the meantime, I think I am settled on the implementation. Would love your feedback as soon as you have time.

[rullzer]

Looks sane to me. Let me get the others in here.

[blizzz]

code looks good, didn't test

[rcdailey]

Do you prefer the target branch be master?

On an unrelated note, I find the way your developers do backports of fixes to stable branches confusing & unintuitive. Normally, hotfixes are applied to your stable releases and merged to your development branches (e.g. stable15 merges to master). Not doing this makes your git history look crazy, which it does, and you probably can't merge branches due to the fact that this also doesn't establish commit ancestry since you do cherry picks.

In any case, take it as general feedback, but we won't solve process issues here. I had to keep it on stable15 for my own personal testing, but I can rebase to master if that is required. Just please bear in mind I do not plan to do any testing on master since I do not have a staging environment. Please let me know where to go from here. I'm sure you're busy, but I was really hoping to get this merged in quicker since it's blocking me, and I don't like making docker image builds off my fork.

[rcdailey]

@rullzer Sorry to keep pinging you. Could I get an update on this? When can we merge it? I want it off my plate. Thanks !

[kesselb]

Do you prefer the target branch be master?

Yes

I can't consistently get Nextcloud to execute the checkServer() code. Seems to happen non-deterministically. Advice on how to properly reproduce the server check logic would be very helpful.

server/lib/private/legacy/util.php

Lines 726 to 728 in 99d86ea

	if (\OC::$server->getSession()->exists('checkServer_succeeded') && \OC::$server->getSession()->get('checkServer_succeeded')) {
	return $errors;
	}

Try to comment the block above. It seems that checkServer is cached per session.

[rcdailey]

@danielkesselberg I have rebased my branch onto master and made some of your suggested corrections. Please let me know if there is anything else required before it can be merged.

[rullzer]

Lets do this 🚀

[welcome]

Thanks for your first pull request and welcome to the community! Feel free to keep them coming! If you are looking for issues to tackle then have a look at this selection: https://github.com/nextcloud/server/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22
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[rullzer]

/backport to stable15

[backportbot-nextcloud]

backport to stable15 in #13906

[cgmastertecnology]

still not solved…getting crazy with NFS /data mount because of no write/read permission on folder
i can't install NC

I # following files:

/usr/src/nextcloud/lib/private/legacy/OC_Util.php
/var/www/html/lib/private/legacy/OC_Util.php

lines:
“Check if there is a writable install folder” and "Check if config folder is writable"

i can write on data folder from inside the container
Any suggestion?

My dockerfile:

version: "2"
services:
nextcloud:
image: nextcloud
container_name: nextcloud
environment:

• PUID=${PUID}
• PGID=${PGID}
• TZ=${TZ}
• NEXTCLOUD_DATA_DIR=/data
  volumes:
• /home/**************/Docker/Nextcloud/Config:/var/www/html
• nfs-data:/data
  ports:
• 444:443
• 4488:80
  restart: unless-stopped
  depends_on:
• nextcloud_db

nextcloud_db:
image: linuxserver/mariadb
container_name: nextcloud_db
environment:

• PUID=${PUID}
• PGID=${PGID}
• MYSQL_ROOT_PASSWORD=************
• TZ=${TZ}
• MYSQL_DATABASE=nextcloud_db
• MYSQL_USER=nextcloud
• MYSQL_PASSWORD=**************
  volumes:
• /home/*********/Docker/Nextcloud/mariadb:/config
  restart: unless-stopped

volumes:
nfs-data:
driver_opts:
type: nfs4
o: addr=192.168.111.50,nfsvers=4,rw
device: :/volume1/Nextcloud/

[smarwei]

In case anyone else still has problems with NFS and finds this ticket: I'm mounting the data directory with samba now and it works fine.