[Bug]: Files bigger than half available server space, fail to upload.

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• Nextcloud Server is running on 64bit capable CPU, PHP and OS.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

With chunking on, chunks go to /data/dev/uploads/<UUID>, after which it appears they are cat'd to the final file, and then the chunks are removed. This ends up using twice as much space as the size of the file. If instead you did:

for f in <UUID>/*; do 
    cat $f >> final_file && rm $f
done

then you wouldn't be filling up the space on my server.

(I'll add that with chunking off, I am also unable to upload a file larger than half my server storage space.)

Steps to reproduce

Upload a file with chunking on. When the file is of size greater than half the size available on the server, the upload fails.

Expected behavior

I'd expect a file smaller than the available space on my server to properly upload.

Installation method

Community Web installer on a VPS or web space

Nextcloud Server version

25.0.6

Operating system

RHEL/CentOS

PHP engine version

PHP 7.4

Web server

Nginx

Database engine version

PostgreSQL

Is this bug present after an update or on a fresh install?

Updated to a major version (ex. 22.2.3 to 23.0.1)

Are you using the Nextcloud Server Encryption module?

None

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

{
    "system": {
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "nextcloud.niwas.net"
        ],
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "pgsql",
        "version": "25.0.6.1",
        "overwrite.cli.url": "https:\/\/nextcloud.niwas.net",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "memcache.local": "\\OC\\Memcache\\Memcached",
        "memcache.distributed": "\\OC\\Memcache\\Memcached",
        "memcached_servers": [
            [
                "\/home\/dev\/logs\/apps\/niwas_nextcloud\/memcached.sock",
                0
            ]
        ],
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "opcache.interned_strings_buffer": "10",
        "default_phone_region": "US",
        "maintenance": false,
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpmode": "smtp",
        "mail_sendmailmode": "smtp",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpsecure": "ssl",
        "mail_smtpauthtype": "LOGIN",
        "mail_smtpauth": 1,
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "465",
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "theme": "",
        "loglevel": 2,
        "updater.secret": "***REMOVED SENSITIVE VALUE***"
    }
}

List of activated Apps

Enabled:
  - activity: 2.17.0
  - bookmarks: 12.1.0
  - breezedark: 25.0.2
  - calendar: 4.3.3
  - circles: 25.0.0
  - cloud_federation_api: 1.8.0
  - comments: 1.15.0
  - contacts: 5.2.0
  - contactsinteraction: 1.6.0
  - dashboard: 7.5.0
  - dav: 1.24.0
  - deck: 1.8.3
  - federatedfilesharing: 1.15.0
  - federation: 1.15.0
  - files: 1.20.1
  - files_markdown: 2.4.0
  - files_pdfviewer: 2.6.0
  - files_rightclick: 1.4.0
  - files_sharing: 1.17.0
  - files_texteditor: 2.15.0
  - files_trashbin: 1.15.0
  - files_versions: 1.18.0
  - firstrunwizard: 2.14.0
  - guests: 2.4.0
  - integration_google: 1.0.9
  - logreader: 2.10.0
  - lookup_server_connector: 1.13.0
  - nextcloud_announcements: 1.14.0
  - notes: 4.7.2
  - notifications: 2.13.1
  - oauth2: 1.13.0
  - password_policy: 1.15.0
  - passwords: 2023.3.11
  - photos: 2.0.1
  - privacy: 1.9.0
  - provisioning_api: 1.15.0
  - recommendations: 1.4.0
  - related_resources: 1.0.4
  - serverinfo: 1.15.0
  - settings: 1.7.0
  - sharebymail: 1.15.0
  - spreed: 15.0.5
  - support: 1.8.0
  - survey_client: 1.13.0
  - systemtags: 1.15.0
  - tasks: 0.14.5
  - text: 3.6.0
  - theming: 2.0.1
  - twofactor_backupcodes: 1.14.0
  - updatenotification: 1.15.0
  - user_status: 1.5.0
  - viewer: 1.9.0
  - weather_status: 1.5.0
  - workflowengine: 2.7.0
Disabled:
  - admin_audit
  - bruteforcesettings
  - encryption
  - files_external
  - suspicious_login
  - twofactor_totp
  - user_ldap

Nextcloud Signing status

No response

Nextcloud Logs

No response

Additional info

No response

Start by tracing the chunked-upload flow described in the issue, including temporary chunks under /data/dev/uploads/ and their assembly into the final file. Reproduce with a file larger than half the available storage, then verify that a file smaller than the available space uploads without requiring duplicate full-file storage.